Merge branch 'android-4.4' of https://android.googlesource.com/kernel/common

[firefly-linux-kernel-4.4.55.git] / drivers / clk / clk.c

/*
 * Copyright (C) 2010-2011 Canonical Ltd <jeremy.kerr@canonical.com>
 * Copyright (C) 2011-2012 Linaro Ltd <mturquette@linaro.org>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 *
 * Standard functionality for the common clock API.  See Documentation/clk.txt
 */

#include <linux/clk.h>
#include <linux/clk-provider.h>
#include <linux/clk/clk-conf.h>
#include <linux/module.h>
#include <linux/mutex.h>
#include <linux/spinlock.h>
#include <linux/err.h>
#include <linux/list.h>
#include <linux/slab.h>
#include <linux/of.h>
#include <linux/device.h>
#include <linux/init.h>
#include <linux/sched.h>
#include <linux/clkdev.h>

#include "clk.h"

static DEFINE_SPINLOCK(enable_lock);
static DEFINE_MUTEX(prepare_lock);

static struct task_struct *prepare_owner;
static struct task_struct *enable_owner;

static int prepare_refcnt;
static int enable_refcnt;

static HLIST_HEAD(clk_root_list);
static HLIST_HEAD(clk_orphan_list);
static LIST_HEAD(clk_notifier_list);

/***    private data structures    ***/

struct clk_core {
        const char              *name;
        const struct clk_ops    *ops;
        struct clk_hw           *hw;
        struct module           *owner;
        struct clk_core         *parent;
        const char              **parent_names;
        struct clk_core         **parents;
        u8                      num_parents;
        u8                      new_parent_index;
        unsigned long           rate;
        unsigned long           req_rate;
        unsigned long           new_rate;
        struct clk_core         *new_parent;
        struct clk_core         *new_child;
        unsigned long           flags;
        bool                    orphan;
        unsigned int            enable_count;
        unsigned int            prepare_count;
        unsigned long           min_rate;
        unsigned long           max_rate;
        unsigned long           accuracy;
        int                     phase;
        struct hlist_head       children;
        struct hlist_node       child_node;
        struct hlist_head       clks;
        unsigned int            notifier_count;
#ifdef CONFIG_DEBUG_FS
        struct dentry           *dentry;
        struct hlist_node       debug_node;
#endif
        struct kref             ref;
};

#define CREATE_TRACE_POINTS
#include <trace/events/clk.h>

struct clk {
        struct clk_core *core;
        const char *dev_id;
        const char *con_id;
        unsigned long min_rate;
        unsigned long max_rate;
        struct hlist_node clks_node;
};

/***           locking             ***/
static void clk_prepare_lock(void)
{
        if (!mutex_trylock(&prepare_lock)) {
                if (prepare_owner == current) {
                        prepare_refcnt++;
                        return;
                }
                mutex_lock(&prepare_lock);
        }
        WARN_ON_ONCE(prepare_owner != NULL);
        WARN_ON_ONCE(prepare_refcnt != 0);
        prepare_owner = current;
        prepare_refcnt = 1;
}

static void clk_prepare_unlock(void)
{
        WARN_ON_ONCE(prepare_owner != current);
        WARN_ON_ONCE(prepare_refcnt == 0);

        if (--prepare_refcnt)
                return;
        prepare_owner = NULL;
        mutex_unlock(&prepare_lock);
}

static unsigned long clk_enable_lock(void)
        __acquires(enable_lock)
{
        unsigned long flags;

        if (!spin_trylock_irqsave(&enable_lock, flags)) {
                if (enable_owner == current) {
                        enable_refcnt++;
                        __acquire(enable_lock);
                        return flags;
                }
                spin_lock_irqsave(&enable_lock, flags);
        }
        WARN_ON_ONCE(enable_owner != NULL);
        WARN_ON_ONCE(enable_refcnt != 0);
        enable_owner = current;
        enable_refcnt = 1;
        return flags;
}

static void clk_enable_unlock(unsigned long flags)
        __releases(enable_lock)
{
        WARN_ON_ONCE(enable_owner != current);
        WARN_ON_ONCE(enable_refcnt == 0);

        if (--enable_refcnt) {
                __release(enable_lock);
                return;
        }
        enable_owner = NULL;
        spin_unlock_irqrestore(&enable_lock, flags);
}

static bool clk_core_is_prepared(struct clk_core *core)
{
        /*
         * .is_prepared is optional for clocks that can prepare
         * fall back to software usage counter if it is missing
         */
        if (!core->ops->is_prepared)
                return core->prepare_count;

        return core->ops->is_prepared(core->hw);
}

static bool clk_core_is_enabled(struct clk_core *core)
{
        /*
         * .is_enabled is only mandatory for clocks that gate
         * fall back to software usage counter if .is_enabled is missing
         */
        if (!core->ops->is_enabled)
                return core->enable_count;

        return core->ops->is_enabled(core->hw);
}

static void clk_unprepare_unused_subtree(struct clk_core *core)
{
        struct clk_core *child;

        lockdep_assert_held(&prepare_lock);

        hlist_for_each_entry(child, &core->children, child_node)
                clk_unprepare_unused_subtree(child);

        if (core->prepare_count)
                return;

        if (core->flags & CLK_IGNORE_UNUSED)
                return;

        if (clk_core_is_prepared(core)) {
                trace_clk_unprepare(core);
                if (core->ops->unprepare_unused)
                        core->ops->unprepare_unused(core->hw);
                else if (core->ops->unprepare)
                        core->ops->unprepare(core->hw);
                trace_clk_unprepare_complete(core);
        }
}

static void clk_disable_unused_subtree(struct clk_core *core)
{
        struct clk_core *child;
        unsigned long flags;

        lockdep_assert_held(&prepare_lock);

        hlist_for_each_entry(child, &core->children, child_node)
                clk_disable_unused_subtree(child);

        flags = clk_enable_lock();

        if (core->enable_count)
                goto unlock_out;

        if (core->flags & CLK_IGNORE_UNUSED)
                goto unlock_out;

        /*
         * some gate clocks have special needs during the disable-unused
         * sequence.  call .disable_unused if available, otherwise fall
         * back to .disable
         */
        if (clk_core_is_enabled(core)) {
                trace_clk_disable(core);
                if (core->ops->disable_unused)
                        core->ops->disable_unused(core->hw);
                else if (core->ops->disable)
                        core->ops->disable(core->hw);
                trace_clk_disable_complete(core);
        }

unlock_out:
        clk_enable_unlock(flags);
}

static bool clk_ignore_unused;
static int __init clk_ignore_unused_setup(char *__unused)
{
        clk_ignore_unused = true;
        return 1;
}
__setup("clk_ignore_unused", clk_ignore_unused_setup);

static int clk_disable_unused(void)
{
        struct clk_core *core;

        if (clk_ignore_unused) {
                pr_warn("clk: Not disabling unused clocks\n");
                return 0;
        }

        clk_prepare_lock();

        hlist_for_each_entry(core, &clk_root_list, child_node)
                clk_disable_unused_subtree(core);

        hlist_for_each_entry(core, &clk_orphan_list, child_node)
                clk_disable_unused_subtree(core);

        hlist_for_each_entry(core, &clk_root_list, child_node)
                clk_unprepare_unused_subtree(core);

        hlist_for_each_entry(core, &clk_orphan_list, child_node)
                clk_unprepare_unused_subtree(core);

        clk_prepare_unlock();

        return 0;
}
late_initcall_sync(clk_disable_unused);

/***    helper functions   ***/

const char *__clk_get_name(const struct clk *clk)
{
        return !clk ? NULL : clk->core->name;
}
EXPORT_SYMBOL_GPL(__clk_get_name);

const char *clk_hw_get_name(const struct clk_hw *hw)
{
        return hw->core->name;
}
EXPORT_SYMBOL_GPL(clk_hw_get_name);

struct clk_hw *__clk_get_hw(struct clk *clk)
{
        return !clk ? NULL : clk->core->hw;
}
EXPORT_SYMBOL_GPL(__clk_get_hw);

unsigned int clk_hw_get_num_parents(const struct clk_hw *hw)
{
        return hw->core->num_parents;
}
EXPORT_SYMBOL_GPL(clk_hw_get_num_parents);

struct clk_hw *clk_hw_get_parent(const struct clk_hw *hw)
{
        return hw->core->parent ? hw->core->parent->hw : NULL;
}
EXPORT_SYMBOL_GPL(clk_hw_get_parent);

static struct clk_core *__clk_lookup_subtree(const char *name,
                                             struct clk_core *core)
{
        struct clk_core *child;
        struct clk_core *ret;

        if (!strcmp(core->name, name))
                return core;

        hlist_for_each_entry(child, &core->children, child_node) {
                ret = __clk_lookup_subtree(name, child);
                if (ret)
                        return ret;
        }

        return NULL;
}

static struct clk_core *clk_core_lookup(const char *name)
{
        struct clk_core *root_clk;
        struct clk_core *ret;

        if (!name)
                return NULL;

        /* search the 'proper' clk tree first */
        hlist_for_each_entry(root_clk, &clk_root_list, child_node) {
                ret = __clk_lookup_subtree(name, root_clk);
                if (ret)
                        return ret;
        }

        /* if not found, then search the orphan tree */
        hlist_for_each_entry(root_clk, &clk_orphan_list, child_node) {
                ret = __clk_lookup_subtree(name, root_clk);
                if (ret)
                        return ret;
        }

        return NULL;
}

static struct clk_core *clk_core_get_parent_by_index(struct clk_core *core,
                                                         u8 index)
{
        if (!core || index >= core->num_parents)
                return NULL;
        else if (!core->parents)
                return clk_core_lookup(core->parent_names[index]);
        else if (!core->parents[index])
                return core->parents[index] =
                        clk_core_lookup(core->parent_names[index]);
        else
                return core->parents[index];
}

struct clk_hw *
clk_hw_get_parent_by_index(const struct clk_hw *hw, unsigned int index)
{
        struct clk_core *parent;

        parent = clk_core_get_parent_by_index(hw->core, index);

        return !parent ? NULL : parent->hw;
}
EXPORT_SYMBOL_GPL(clk_hw_get_parent_by_index);

unsigned int __clk_get_enable_count(struct clk *clk)
{
        return !clk ? 0 : clk->core->enable_count;
}

static unsigned long clk_core_get_rate_nolock(struct clk_core *core)
{
        unsigned long ret;

        if (!core) {
                ret = 0;
                goto out;
        }

        ret = core->rate;

        if (core->flags & CLK_IS_ROOT)
                goto out;

        if (!core->parent)
                ret = 0;

out:
        return ret;
}

unsigned long clk_hw_get_rate(const struct clk_hw *hw)
{
        return clk_core_get_rate_nolock(hw->core);
}
EXPORT_SYMBOL_GPL(clk_hw_get_rate);

static unsigned long __clk_get_accuracy(struct clk_core *core)
{
        if (!core)
                return 0;

        return core->accuracy;
}

unsigned long __clk_get_flags(struct clk *clk)
{
        return !clk ? 0 : clk->core->flags;
}
EXPORT_SYMBOL_GPL(__clk_get_flags);

unsigned long clk_hw_get_flags(const struct clk_hw *hw)
{
        return hw->core->flags;
}
EXPORT_SYMBOL_GPL(clk_hw_get_flags);

bool clk_hw_is_prepared(const struct clk_hw *hw)
{
        return clk_core_is_prepared(hw->core);
}

bool clk_hw_is_enabled(const struct clk_hw *hw)
{
        return clk_core_is_enabled(hw->core);
}

bool __clk_is_enabled(struct clk *clk)
{
        if (!clk)
                return false;

        return clk_core_is_enabled(clk->core);
}
EXPORT_SYMBOL_GPL(__clk_is_enabled);

static bool mux_is_better_rate(unsigned long rate, unsigned long now,
                           unsigned long best, unsigned long flags)
{
        if (flags & CLK_MUX_ROUND_CLOSEST)
                return abs(now - rate) < abs(best - rate);

        return now <= rate && now > best;
}

static int
clk_mux_determine_rate_flags(struct clk_hw *hw, struct clk_rate_request *req,
                             unsigned long flags)
{
        struct clk_core *core = hw->core, *parent, *best_parent = NULL;
        int i, num_parents, ret;
        unsigned long best = 0;
        struct clk_rate_request parent_req = *req;

        /* if NO_REPARENT flag set, pass through to current parent */
        if (core->flags & CLK_SET_RATE_NO_REPARENT) {
                parent = core->parent;
                if (core->flags & CLK_SET_RATE_PARENT) {
                        ret = __clk_determine_rate(parent ? parent->hw : NULL,
                                                   &parent_req);
                        if (ret)
                                return ret;

                        best = parent_req.rate;
                } else if (parent) {
                        best = clk_core_get_rate_nolock(parent);
                } else {
                        best = clk_core_get_rate_nolock(core);
                }

                goto out;
        }

        /* find the parent that can provide the fastest rate <= rate */
        num_parents = core->num_parents;
        for (i = 0; i < num_parents; i++) {
                parent = clk_core_get_parent_by_index(core, i);
                if (!parent)
                        continue;

                if (core->flags & CLK_SET_RATE_PARENT) {
                        parent_req = *req;
                        ret = __clk_determine_rate(parent->hw, &parent_req);
                        if (ret)
                                continue;
                } else {
                        parent_req.rate = clk_core_get_rate_nolock(parent);
                }

                if (mux_is_better_rate(req->rate, parent_req.rate,
                                       best, flags)) {
                        best_parent = parent;
                        best = parent_req.rate;
                }
        }

        if (!best_parent)
                return -EINVAL;

out:
        if (best_parent)
                req->best_parent_hw = best_parent->hw;
        req->best_parent_rate = best;
        req->rate = best;

        return 0;
}

struct clk *__clk_lookup(const char *name)
{
        struct clk_core *core = clk_core_lookup(name);

        return !core ? NULL : core->hw->clk;
}

static void clk_core_get_boundaries(struct clk_core *core,
                                    unsigned long *min_rate,
                                    unsigned long *max_rate)
{
        struct clk *clk_user;

        *min_rate = core->min_rate;
        *max_rate = core->max_rate;

        hlist_for_each_entry(clk_user, &core->clks, clks_node)
                *min_rate = max(*min_rate, clk_user->min_rate);

        hlist_for_each_entry(clk_user, &core->clks, clks_node)
                *max_rate = min(*max_rate, clk_user->max_rate);
}

void clk_hw_set_rate_range(struct clk_hw *hw, unsigned long min_rate,
                           unsigned long max_rate)
{
        hw->core->min_rate = min_rate;
        hw->core->max_rate = max_rate;
}
EXPORT_SYMBOL_GPL(clk_hw_set_rate_range);

/*
 * Helper for finding best parent to provide a given frequency. This can be used
 * directly as a determine_rate callback (e.g. for a mux), or from a more
 * complex clock that may combine a mux with other operations.
 */
int __clk_mux_determine_rate(struct clk_hw *hw,
                             struct clk_rate_request *req)
{
        return clk_mux_determine_rate_flags(hw, req, 0);
}
EXPORT_SYMBOL_GPL(__clk_mux_determine_rate);

int __clk_mux_determine_rate_closest(struct clk_hw *hw,
                                     struct clk_rate_request *req)
{
        return clk_mux_determine_rate_flags(hw, req, CLK_MUX_ROUND_CLOSEST);
}
EXPORT_SYMBOL_GPL(__clk_mux_determine_rate_closest);

/***        clk api        ***/

static void clk_core_unprepare(struct clk_core *core)
{
        lockdep_assert_held(&prepare_lock);

        if (!core)
                return;

        if (WARN_ON(core->prepare_count == 0))
                return;

        if (--core->prepare_count > 0)
                return;

        WARN_ON(core->enable_count > 0);

        trace_clk_unprepare(core);

        if (core->ops->unprepare)
                core->ops->unprepare(core->hw);

        trace_clk_unprepare_complete(core);
        clk_core_unprepare(core->parent);
}

/**
 * clk_unprepare - undo preparation of a clock source
 * @clk: the clk being unprepared
 *
 * clk_unprepare may sleep, which differentiates it from clk_disable.  In a
 * simple case, clk_unprepare can be used instead of clk_disable to gate a clk
 * if the operation may sleep.  One example is a clk which is accessed over
 * I2c.  In the complex case a clk gate operation may require a fast and a slow
 * part.  It is this reason that clk_unprepare and clk_disable are not mutually
 * exclusive.  In fact clk_disable must be called before clk_unprepare.
 */
void clk_unprepare(struct clk *clk)
{
        if (IS_ERR_OR_NULL(clk))
                return;

        clk_prepare_lock();
        clk_core_unprepare(clk->core);
        clk_prepare_unlock();
}
EXPORT_SYMBOL_GPL(clk_unprepare);

static int clk_core_prepare(struct clk_core *core)
{
        int ret = 0;

        lockdep_assert_held(&prepare_lock);

        if (!core)
                return 0;

        if (core->prepare_count == 0) {
                ret = clk_core_prepare(core->parent);
                if (ret)
                        return ret;

                trace_clk_prepare(core);

                if (core->ops->prepare)
                        ret = core->ops->prepare(core->hw);

                trace_clk_prepare_complete(core);

                if (ret) {
                        clk_core_unprepare(core->parent);
                        return ret;
                }
        }

        core->prepare_count++;

        return 0;
}

/**
 * clk_prepare - prepare a clock source
 * @clk: the clk being prepared
 *
 * clk_prepare may sleep, which differentiates it from clk_enable.  In a simple
 * case, clk_prepare can be used instead of clk_enable to ungate a clk if the
 * operation may sleep.  One example is a clk which is accessed over I2c.  In
 * the complex case a clk ungate operation may require a fast and a slow part.
 * It is this reason that clk_prepare and clk_enable are not mutually
 * exclusive.  In fact clk_prepare must be called before clk_enable.
 * Returns 0 on success, -EERROR otherwise.
 */
int clk_prepare(struct clk *clk)
{
        int ret;

        if (!clk)
                return 0;

        clk_prepare_lock();
        ret = clk_core_prepare(clk->core);
        clk_prepare_unlock();

        return ret;
}
EXPORT_SYMBOL_GPL(clk_prepare);

static void clk_core_disable(struct clk_core *core)
{
        lockdep_assert_held(&enable_lock);

        if (!core)
                return;

        if (WARN_ON(core->enable_count == 0))
                return;

        if (--core->enable_count > 0)
                return;

        trace_clk_disable(core);

        if (core->ops->disable)
                core->ops->disable(core->hw);

        trace_clk_disable_complete(core);

        clk_core_disable(core->parent);
}

/**
 * clk_disable - gate a clock
 * @clk: the clk being gated
 *
 * clk_disable must not sleep, which differentiates it from clk_unprepare.  In
 * a simple case, clk_disable can be used instead of clk_unprepare to gate a
 * clk if the operation is fast and will never sleep.  One example is a
 * SoC-internal clk which is controlled via simple register writes.  In the
 * complex case a clk gate operation may require a fast and a slow part.  It is
 * this reason that clk_unprepare and clk_disable are not mutually exclusive.
 * In fact clk_disable must be called before clk_unprepare.
 */
void clk_disable(struct clk *clk)
{
        unsigned long flags;

        if (IS_ERR_OR_NULL(clk))
                return;

        flags = clk_enable_lock();
        clk_core_disable(clk->core);
        clk_enable_unlock(flags);
}
EXPORT_SYMBOL_GPL(clk_disable);

static int clk_core_enable(struct clk_core *core)
{
        int ret = 0;

        lockdep_assert_held(&enable_lock);

        if (!core)
                return 0;

        if (WARN_ON(core->prepare_count == 0))
                return -ESHUTDOWN;

        if (core->enable_count == 0) {
                ret = clk_core_enable(core->parent);

                if (ret)
                        return ret;

                trace_clk_enable(core);

                if (core->ops->enable)
                        ret = core->ops->enable(core->hw);

                trace_clk_enable_complete(core);

                if (ret) {
                        clk_core_disable(core->parent);
                        return ret;
                }
        }

        core->enable_count++;
        return 0;
}

/**
 * clk_enable - ungate a clock
 * @clk: the clk being ungated
 *
 * clk_enable must not sleep, which differentiates it from clk_prepare.  In a
 * simple case, clk_enable can be used instead of clk_prepare to ungate a clk
 * if the operation will never sleep.  One example is a SoC-internal clk which
 * is controlled via simple register writes.  In the complex case a clk ungate
 * operation may require a fast and a slow part.  It is this reason that
 * clk_enable and clk_prepare are not mutually exclusive.  In fact clk_prepare
 * must be called before clk_enable.  Returns 0 on success, -EERROR
 * otherwise.
 */
int clk_enable(struct clk *clk)
{
        unsigned long flags;
        int ret;

        if (!clk)
                return 0;

        flags = clk_enable_lock();
        ret = clk_core_enable(clk->core);
        clk_enable_unlock(flags);

        return ret;
}
EXPORT_SYMBOL_GPL(clk_enable);

static int clk_core_round_rate_nolock(struct clk_core *core,
                                      struct clk_rate_request *req)
{
        struct clk_core *parent;
        long rate;

        lockdep_assert_held(&prepare_lock);

        if (!core)
                return 0;

        parent = core->parent;
        if (parent) {
                req->best_parent_hw = parent->hw;
                req->best_parent_rate = parent->rate;
        } else {
                req->best_parent_hw = NULL;
                req->best_parent_rate = 0;
        }

        if (core->ops->determine_rate) {
                return core->ops->determine_rate(core->hw, req);
        } else if (core->ops->round_rate) {
                rate = core->ops->round_rate(core->hw, req->rate,
                                             &req->best_parent_rate);
                if (rate < 0)
                        return rate;

                req->rate = rate;
        } else if (core->flags & CLK_SET_RATE_PARENT) {
                return clk_core_round_rate_nolock(parent, req);
        } else {
                req->rate = core->rate;
        }

        return 0;
}

/**
 * __clk_determine_rate - get the closest rate actually supported by a clock
 * @hw: determine the rate of this clock
 * @rate: target rate
 * @min_rate: returned rate must be greater than this rate
 * @max_rate: returned rate must be less than this rate
 *
 * Useful for clk_ops such as .set_rate and .determine_rate.
 */
int __clk_determine_rate(struct clk_hw *hw, struct clk_rate_request *req)
{
        if (!hw) {
                req->rate = 0;
                return 0;
        }

        return clk_core_round_rate_nolock(hw->core, req);
}
EXPORT_SYMBOL_GPL(__clk_determine_rate);

unsigned long clk_hw_round_rate(struct clk_hw *hw, unsigned long rate)
{
        int ret;
        struct clk_rate_request req;

        clk_core_get_boundaries(hw->core, &req.min_rate, &req.max_rate);
        req.rate = rate;

        ret = clk_core_round_rate_nolock(hw->core, &req);
        if (ret)
                return 0;

        return req.rate;
}
EXPORT_SYMBOL_GPL(clk_hw_round_rate);

/**
 * clk_round_rate - round the given rate for a clk
 * @clk: the clk for which we are rounding a rate
 * @rate: the rate which is to be rounded
 *
 * Takes in a rate as input and rounds it to a rate that the clk can actually
 * use which is then returned.  If clk doesn't support round_rate operation
 * then the parent rate is returned.
 */
long clk_round_rate(struct clk *clk, unsigned long rate)
{
        struct clk_rate_request req;
        int ret;

        if (!clk)
                return 0;

        clk_prepare_lock();

        clk_core_get_boundaries(clk->core, &req.min_rate, &req.max_rate);
        req.rate = rate;

        ret = clk_core_round_rate_nolock(clk->core, &req);
        clk_prepare_unlock();

        if (ret)
                return ret;

        return req.rate;
}
EXPORT_SYMBOL_GPL(clk_round_rate);

/**
 * __clk_notify - call clk notifier chain
 * @core: clk that is changing rate
 * @msg: clk notifier type (see include/linux/clk.h)
 * @old_rate: old clk rate
 * @new_rate: new clk rate
 *
 * Triggers a notifier call chain on the clk rate-change notification
 * for 'clk'.  Passes a pointer to the struct clk and the previous
 * and current rates to the notifier callback.  Intended to be called by
 * internal clock code only.  Returns NOTIFY_DONE from the last driver
 * called if all went well, or NOTIFY_STOP or NOTIFY_BAD immediately if
 * a driver returns that.
 */
static int __clk_notify(struct clk_core *core, unsigned long msg,
                unsigned long old_rate, unsigned long new_rate)
{
        struct clk_notifier *cn;
        struct clk_notifier_data cnd;
        int ret = NOTIFY_DONE;

        cnd.old_rate = old_rate;
        cnd.new_rate = new_rate;

        list_for_each_entry(cn, &clk_notifier_list, node) {
                if (cn->clk->core == core) {
                        cnd.clk = cn->clk;
                        ret = srcu_notifier_call_chain(&cn->notifier_head, msg,
                                        &cnd);
                }
        }

        return ret;
}

/**
 * __clk_recalc_accuracies
 * @core: first clk in the subtree
 *
 * Walks the subtree of clks starting with clk and recalculates accuracies as
 * it goes.  Note that if a clk does not implement the .recalc_accuracy
 * callback then it is assumed that the clock will take on the accuracy of its
 * parent.
 */
static void __clk_recalc_accuracies(struct clk_core *core)
{
        unsigned long parent_accuracy = 0;
        struct clk_core *child;

        lockdep_assert_held(&prepare_lock);

        if (core->parent)
                parent_accuracy = core->parent->accuracy;

        if (core->ops->recalc_accuracy)
                core->accuracy = core->ops->recalc_accuracy(core->hw,
                                                          parent_accuracy);
        else
                core->accuracy = parent_accuracy;

        hlist_for_each_entry(child, &core->children, child_node)
                __clk_recalc_accuracies(child);
}

static long clk_core_get_accuracy(struct clk_core *core)
{
        unsigned long accuracy;

        clk_prepare_lock();
        if (core && (core->flags & CLK_GET_ACCURACY_NOCACHE))
                __clk_recalc_accuracies(core);

        accuracy = __clk_get_accuracy(core);
        clk_prepare_unlock();

        return accuracy;
}

/**
 * clk_get_accuracy - return the accuracy of clk
 * @clk: the clk whose accuracy is being returned
 *
 * Simply returns the cached accuracy of the clk, unless
 * CLK_GET_ACCURACY_NOCACHE flag is set, which means a recalc_rate will be
 * issued.
 * If clk is NULL then returns 0.
 */
long clk_get_accuracy(struct clk *clk)
{
        if (!clk)
                return 0;

        return clk_core_get_accuracy(clk->core);
}
EXPORT_SYMBOL_GPL(clk_get_accuracy);

static unsigned long clk_recalc(struct clk_core *core,
                                unsigned long parent_rate)
{
        if (core->ops->recalc_rate)
                return core->ops->recalc_rate(core->hw, parent_rate);
        return parent_rate;
}

/**
 * __clk_recalc_rates
 * @core: first clk in the subtree
 * @msg: notification type (see include/linux/clk.h)
 *
 * Walks the subtree of clks starting with clk and recalculates rates as it
 * goes.  Note that if a clk does not implement the .recalc_rate callback then
 * it is assumed that the clock will take on the rate of its parent.
 *
 * clk_recalc_rates also propagates the POST_RATE_CHANGE notification,
 * if necessary.
 */
static void __clk_recalc_rates(struct clk_core *core, unsigned long msg)
{
        unsigned long old_rate;
        unsigned long parent_rate = 0;
        struct clk_core *child;

        lockdep_assert_held(&prepare_lock);

        old_rate = core->rate;

        if (core->parent)
                parent_rate = core->parent->rate;

        core->rate = clk_recalc(core, parent_rate);

        /*
         * ignore NOTIFY_STOP and NOTIFY_BAD return values for POST_RATE_CHANGE
         * & ABORT_RATE_CHANGE notifiers
         */
        if (core->notifier_count && msg)
                __clk_notify(core, msg, old_rate, core->rate);

        hlist_for_each_entry(child, &core->children, child_node)
                __clk_recalc_rates(child, msg);
}

static unsigned long clk_core_get_rate(struct clk_core *core)
{
        unsigned long rate;

        clk_prepare_lock();

        if (core && (core->flags & CLK_GET_RATE_NOCACHE))
                __clk_recalc_rates(core, 0);

        rate = clk_core_get_rate_nolock(core);
        clk_prepare_unlock();

        return rate;
}

/**
 * clk_get_rate - return the rate of clk
 * @clk: the clk whose rate is being returned
 *
 * Simply returns the cached rate of the clk, unless CLK_GET_RATE_NOCACHE flag
 * is set, which means a recalc_rate will be issued.
 * If clk is NULL then returns 0.
 */
unsigned long clk_get_rate(struct clk *clk)
{
        if (!clk)
                return 0;

        return clk_core_get_rate(clk->core);
}
EXPORT_SYMBOL_GPL(clk_get_rate);

static int clk_fetch_parent_index(struct clk_core *core,
                                  struct clk_core *parent)
{
        int i;

        if (!core->parents) {
                core->parents = kcalloc(core->num_parents,
                                        sizeof(struct clk *), GFP_KERNEL);
                if (!core->parents)
                        return -ENOMEM;
        }

        /*
         * find index of new parent clock using cached parent ptrs,
         * or if not yet cached, use string name comparison and cache
         * them now to avoid future calls to clk_core_lookup.
         */
        for (i = 0; i < core->num_parents; i++) {
                if (core->parents[i] == parent)
                        return i;

                if (core->parents[i])
                        continue;

                if (!strcmp(core->parent_names[i], parent->name)) {
                        core->parents[i] = clk_core_lookup(parent->name);
                        return i;
                }
        }

        return -EINVAL;
}

/*
 * Update the orphan status of @core and all its children.
 */
static void clk_core_update_orphan_status(struct clk_core *core, bool is_orphan)
{
        struct clk_core *child;

        core->orphan = is_orphan;

        hlist_for_each_entry(child, &core->children, child_node)
                clk_core_update_orphan_status(child, is_orphan);
}

static void clk_reparent(struct clk_core *core, struct clk_core *new_parent)
{
        bool was_orphan = core->orphan;

        hlist_del(&core->child_node);

        if (new_parent) {
                bool becomes_orphan = new_parent->orphan;

                /* avoid duplicate POST_RATE_CHANGE notifications */
                if (new_parent->new_child == core)
                        new_parent->new_child = NULL;

                hlist_add_head(&core->child_node, &new_parent->children);

                if (was_orphan != becomes_orphan)
                        clk_core_update_orphan_status(core, becomes_orphan);
        } else {
                hlist_add_head(&core->child_node, &clk_orphan_list);
                if (!was_orphan)
                        clk_core_update_orphan_status(core, true);
        }

        core->parent = new_parent;
}

static struct clk_core *__clk_set_parent_before(struct clk_core *core,
                                           struct clk_core *parent)
{
        unsigned long flags;
        struct clk_core *old_parent = core->parent;

        /*
         * Migrate prepare state between parents and prevent race with
         * clk_enable().
         *
         * If the clock is not prepared, then a race with
         * clk_enable/disable() is impossible since we already have the
         * prepare lock (future calls to clk_enable() need to be preceded by
         * a clk_prepare()).
         *
         * If the clock is prepared, migrate the prepared state to the new
         * parent and also protect against a race with clk_enable() by
         * forcing the clock and the new parent on.  This ensures that all
         * future calls to clk_enable() are practically NOPs with respect to
         * hardware and software states.
         *
         * See also: Comment for clk_set_parent() below.
         */
        if (core->prepare_count) {
                clk_core_prepare(parent);
                flags = clk_enable_lock();
                clk_core_enable(parent);
                clk_core_enable(core);
                clk_enable_unlock(flags);
        }

        /* update the clk tree topology */
        flags = clk_enable_lock();
        clk_reparent(core, parent);
        clk_enable_unlock(flags);

        return old_parent;
}

static void __clk_set_parent_after(struct clk_core *core,
                                   struct clk_core *parent,
                                   struct clk_core *old_parent)
{
        unsigned long flags;

        /*
         * Finish the migration of prepare state and undo the changes done
         * for preventing a race with clk_enable().
         */
        if (core->prepare_count) {
                flags = clk_enable_lock();
                clk_core_disable(core);
                clk_core_disable(old_parent);
                clk_enable_unlock(flags);
                clk_core_unprepare(old_parent);
        }
}

static int __clk_set_parent(struct clk_core *core, struct clk_core *parent,
                            u8 p_index)
{
        unsigned long flags;
        int ret = 0;
        struct clk_core *old_parent;

        old_parent = __clk_set_parent_before(core, parent);

        trace_clk_set_parent(core, parent);

        /* change clock input source */
        if (parent && core->ops->set_parent)
                ret = core->ops->set_parent(core->hw, p_index);

        trace_clk_set_parent_complete(core, parent);

        if (ret) {
                flags = clk_enable_lock();
                clk_reparent(core, old_parent);
                clk_enable_unlock(flags);
                __clk_set_parent_after(core, old_parent, parent);

                return ret;
        }

        __clk_set_parent_after(core, parent, old_parent);

        return 0;
}

/**
 * __clk_speculate_rates
 * @core: first clk in the subtree
 * @parent_rate: the "future" rate of clk's parent
 *
 * Walks the subtree of clks starting with clk, speculating rates as it
 * goes and firing off PRE_RATE_CHANGE notifications as necessary.
 *
 * Unlike clk_recalc_rates, clk_speculate_rates exists only for sending
 * pre-rate change notifications and returns early if no clks in the
 * subtree have subscribed to the notifications.  Note that if a clk does not
 * implement the .recalc_rate callback then it is assumed that the clock will
 * take on the rate of its parent.
 */
static int __clk_speculate_rates(struct clk_core *core,
                                 unsigned long parent_rate)
{
        struct clk_core *child;
        unsigned long new_rate;
        int ret = NOTIFY_DONE;

        lockdep_assert_held(&prepare_lock);

        new_rate = clk_recalc(core, parent_rate);

        /* abort rate change if a driver returns NOTIFY_BAD or NOTIFY_STOP */
        if (core->notifier_count)
                ret = __clk_notify(core, PRE_RATE_CHANGE, core->rate, new_rate);

        if (ret & NOTIFY_STOP_MASK) {
                pr_debug("%s: clk notifier callback for clock %s aborted with error %d\n",
                                __func__, core->name, ret);
                goto out;
        }

        hlist_for_each_entry(child, &core->children, child_node) {
                ret = __clk_speculate_rates(child, new_rate);
                if (ret & NOTIFY_STOP_MASK)
                        break;
        }

out:
        return ret;
}

static void clk_calc_subtree(struct clk_core *core, unsigned long new_rate,
                             struct clk_core *new_parent, u8 p_index)
{
        struct clk_core *child;

        core->new_rate = new_rate;
        core->new_parent = new_parent;
        core->new_parent_index = p_index;
        /* include clk in new parent's PRE_RATE_CHANGE notifications */
        core->new_child = NULL;
        if (new_parent && new_parent != core->parent)
                new_parent->new_child = core;

        hlist_for_each_entry(child, &core->children, child_node) {
                child->new_rate = clk_recalc(child, new_rate);
                clk_calc_subtree(child, child->new_rate, NULL, 0);
        }
}

/*
 * calculate the new rates returning the topmost clock that has to be
 * changed.
 */
static struct clk_core *clk_calc_new_rates(struct clk_core *core,
                                           unsigned long rate)
{
        struct clk_core *top = core;
        struct clk_core *old_parent, *parent;
        unsigned long best_parent_rate = 0;
        unsigned long new_rate;
        unsigned long min_rate;
        unsigned long max_rate;
        int p_index = 0;
        long ret;

        /* sanity */
        if (IS_ERR_OR_NULL(core))
                return NULL;

        /* save parent rate, if it exists */
        parent = old_parent = core->parent;
        if (parent)
                best_parent_rate = parent->rate;

        clk_core_get_boundaries(core, &min_rate, &max_rate);

        /* find the closest rate and parent clk/rate */
        if (core->ops->determine_rate) {
                struct clk_rate_request req;

                req.rate = rate;
                req.min_rate = min_rate;
                req.max_rate = max_rate;
                if (parent) {
                        req.best_parent_hw = parent->hw;
                        req.best_parent_rate = parent->rate;
                } else {
                        req.best_parent_hw = NULL;
                        req.best_parent_rate = 0;
                }

                ret = core->ops->determine_rate(core->hw, &req);
                if (ret < 0)
                        return NULL;

                best_parent_rate = req.best_parent_rate;
                new_rate = req.rate;
                parent = req.best_parent_hw ? req.best_parent_hw->core : NULL;
        } else if (core->ops->round_rate) {
                ret = core->ops->round_rate(core->hw, rate,
                                            &best_parent_rate);
                if (ret < 0)
                        return NULL;

                new_rate = ret;
                if (new_rate < min_rate || new_rate > max_rate)
                        return NULL;
        } else if (!parent || !(core->flags & CLK_SET_RATE_PARENT)) {
                /* pass-through clock without adjustable parent */
                core->new_rate = core->rate;
                return NULL;
        } else {
                /* pass-through clock with adjustable parent */
                top = clk_calc_new_rates(parent, rate);
                new_rate = parent->new_rate;
                goto out;
        }

        /* some clocks must be gated to change parent */
        if (parent != old_parent &&
            (core->flags & CLK_SET_PARENT_GATE) && core->prepare_count) {
                pr_debug("%s: %s not gated but wants to reparent\n",
                         __func__, core->name);
                return NULL;
        }

        /* try finding the new parent index */
        if (parent && core->num_parents > 1) {
                p_index = clk_fetch_parent_index(core, parent);
                if (p_index < 0) {
                        pr_debug("%s: clk %s can not be parent of clk %s\n",
                                 __func__, parent->name, core->name);
                        return NULL;
                }
        }

        if ((core->flags & CLK_SET_RATE_PARENT) && parent &&
            best_parent_rate != parent->rate)
                top = clk_calc_new_rates(parent, best_parent_rate);

out:
        clk_calc_subtree(core, new_rate, parent, p_index);

        return top;
}

/*
 * Notify about rate changes in a subtree. Always walk down the whole tree
 * so that in case of an error we can walk down the whole tree again and
 * abort the change.
 */
static struct clk_core *clk_propagate_rate_change(struct clk_core *core,
                                                  unsigned long event)
{
        struct clk_core *child, *tmp_clk, *fail_clk = NULL;
        int ret = NOTIFY_DONE;

        if (core->rate == core->new_rate)
                return NULL;

        if (core->notifier_count) {
                ret = __clk_notify(core, event, core->rate, core->new_rate);
                if (ret & NOTIFY_STOP_MASK)
                        fail_clk = core;
        }

        hlist_for_each_entry(child, &core->children, child_node) {
                /* Skip children who will be reparented to another clock */
                if (child->new_parent && child->new_parent != core)
                        continue;
                tmp_clk = clk_propagate_rate_change(child, event);
                if (tmp_clk)
                        fail_clk = tmp_clk;
        }

        /* handle the new child who might not be in core->children yet */
        if (core->new_child) {
                tmp_clk = clk_propagate_rate_change(core->new_child, event);
                if (tmp_clk)
                        fail_clk = tmp_clk;
        }

        return fail_clk;
}

/*
 * walk down a subtree and set the new rates notifying the rate
 * change on the way
 */
static void clk_change_rate(struct clk_core *core)
{
        struct clk_core *child;
        struct hlist_node *tmp;
        unsigned long old_rate;
        unsigned long best_parent_rate = 0;
        bool skip_set_rate = false;
        struct clk_core *old_parent;

        old_rate = core->rate;

        if (core->new_parent)
                best_parent_rate = core->new_parent->rate;
        else if (core->parent)
                best_parent_rate = core->parent->rate;

        if (core->flags & CLK_SET_RATE_UNGATE) {
                unsigned long flags;

                clk_core_prepare(core);
                flags = clk_enable_lock();
                clk_core_enable(core);
                clk_enable_unlock(flags);
        }

        if (core->new_parent && core->new_parent != core->parent) {
                old_parent = __clk_set_parent_before(core, core->new_parent);
                trace_clk_set_parent(core, core->new_parent);

                if (core->ops->set_rate_and_parent) {
                        skip_set_rate = true;
                        core->ops->set_rate_and_parent(core->hw, core->new_rate,
                                        best_parent_rate,
                                        core->new_parent_index);
                } else if (core->ops->set_parent) {
                        core->ops->set_parent(core->hw, core->new_parent_index);
                }

                trace_clk_set_parent_complete(core, core->new_parent);
                __clk_set_parent_after(core, core->new_parent, old_parent);
        }

        trace_clk_set_rate(core, core->new_rate);

        if (!skip_set_rate && core->ops->set_rate)
                core->ops->set_rate(core->hw, core->new_rate, best_parent_rate);

        trace_clk_set_rate_complete(core, core->new_rate);

        core->rate = clk_recalc(core, best_parent_rate);

        if (core->flags & CLK_SET_RATE_UNGATE) {
                unsigned long flags;

                flags = clk_enable_lock();
                clk_core_disable(core);
                clk_enable_unlock(flags);
                clk_core_unprepare(core);
        }

        if (core->notifier_count && old_rate != core->rate)
                __clk_notify(core, POST_RATE_CHANGE, old_rate, core->rate);

        if (core->flags & CLK_RECALC_NEW_RATES)
                (void)clk_calc_new_rates(core, core->new_rate);

        /*
         * Use safe iteration, as change_rate can actually swap parents
         * for certain clock types.
         */
        hlist_for_each_entry_safe(child, tmp, &core->children, child_node) {
                /* Skip children who will be reparented to another clock */
                if (child->new_parent && child->new_parent != core)
                        continue;
                clk_change_rate(child);
        }

        /* handle the new child who might not be in core->children yet */
        if (core->new_child)
                clk_change_rate(core->new_child);
}

static int clk_core_set_rate_nolock(struct clk_core *core,
                                    unsigned long req_rate)
{
        struct clk_core *top, *fail_clk;
        unsigned long rate = req_rate;
        int ret = 0;

        if (!core)
                return 0;

        /* bail early if nothing to do */
        if (rate == clk_core_get_rate_nolock(core))
                return 0;

        if ((core->flags & CLK_SET_RATE_GATE) && core->prepare_count)
                return -EBUSY;

        /* calculate new rates and get the topmost changed clock */
        top = clk_calc_new_rates(core, rate);
        if (!top)
                return -EINVAL;

        /* notify that we are about to change rates */
        fail_clk = clk_propagate_rate_change(top, PRE_RATE_CHANGE);
        if (fail_clk) {
                pr_debug("%s: failed to set %s rate\n", __func__,
                                fail_clk->name);
                clk_propagate_rate_change(top, ABORT_RATE_CHANGE);
                return -EBUSY;
        }

        /* change the rates */
        clk_change_rate(top);

        core->req_rate = req_rate;

        return ret;
}

/**
 * clk_set_rate - specify a new rate for clk
 * @clk: the clk whose rate is being changed
 * @rate: the new rate for clk
 *
 * In the simplest case clk_set_rate will only adjust the rate of clk.
 *
 * Setting the CLK_SET_RATE_PARENT flag allows the rate change operation to
 * propagate up to clk's parent; whether or not this happens depends on the
 * outcome of clk's .round_rate implementation.  If *parent_rate is unchanged
 * after calling .round_rate then upstream parent propagation is ignored.  If
 * *parent_rate comes back with a new rate for clk's parent then we propagate
 * up to clk's parent and set its rate.  Upward propagation will continue
 * until either a clk does not support the CLK_SET_RATE_PARENT flag or
 * .round_rate stops requesting changes to clk's parent_rate.
 *
 * Rate changes are accomplished via tree traversal that also recalculates the
 * rates for the clocks and fires off POST_RATE_CHANGE notifiers.
 *
 * Returns 0 on success, -EERROR otherwise.
 */
int clk_set_rate(struct clk *clk, unsigned long rate)
{
        int ret;

        if (!clk)
                return 0;

        /* prevent racing with updates to the clock topology */
        clk_prepare_lock();

        ret = clk_core_set_rate_nolock(clk->core, rate);

        clk_prepare_unlock();

        return ret;
}
EXPORT_SYMBOL_GPL(clk_set_rate);

/**
 * clk_set_rate_range - set a rate range for a clock source
 * @clk: clock source
 * @min: desired minimum clock rate in Hz, inclusive
 * @max: desired maximum clock rate in Hz, inclusive
 *
 * Returns success (0) or negative errno.
 */
int clk_set_rate_range(struct clk *clk, unsigned long min, unsigned long max)
{
        int ret = 0;

        if (!clk)
                return 0;

        if (min > max) {
                pr_err("%s: clk %s dev %s con %s: invalid range [%lu, %lu]\n",
                       __func__, clk->core->name, clk->dev_id, clk->con_id,
                       min, max);
                return -EINVAL;
        }

        clk_prepare_lock();

        if (min != clk->min_rate || max != clk->max_rate) {
                clk->min_rate = min;
                clk->max_rate = max;
                ret = clk_core_set_rate_nolock(clk->core, clk->core->req_rate);
        }

        clk_prepare_unlock();

        return ret;
}
EXPORT_SYMBOL_GPL(clk_set_rate_range);

/**
 * clk_set_min_rate - set a minimum clock rate for a clock source
 * @clk: clock source
 * @rate: desired minimum clock rate in Hz, inclusive
 *
 * Returns success (0) or negative errno.
 */
int clk_set_min_rate(struct clk *clk, unsigned long rate)
{
        if (!clk)
                return 0;

        return clk_set_rate_range(clk, rate, clk->max_rate);
}
EXPORT_SYMBOL_GPL(clk_set_min_rate);

/**
 * clk_set_max_rate - set a maximum clock rate for a clock source
 * @clk: clock source
 * @rate: desired maximum clock rate in Hz, inclusive
 *
 * Returns success (0) or negative errno.
 */
int clk_set_max_rate(struct clk *clk, unsigned long rate)
{
        if (!clk)
                return 0;

        return clk_set_rate_range(clk, clk->min_rate, rate);
}
EXPORT_SYMBOL_GPL(clk_set_max_rate);

/**
 * clk_get_parent - return the parent of a clk
 * @clk: the clk whose parent gets returned
 *
 * Simply returns clk->parent.  Returns NULL if clk is NULL.
 */
struct clk *clk_get_parent(struct clk *clk)
{
        struct clk *parent;

        if (!clk)
                return NULL;

        clk_prepare_lock();
        /* TODO: Create a per-user clk and change callers to call clk_put */
        parent = !clk->core->parent ? NULL : clk->core->parent->hw->clk;
        clk_prepare_unlock();

        return parent;
}
EXPORT_SYMBOL_GPL(clk_get_parent);

/*
 * .get_parent is mandatory for clocks with multiple possible parents.  It is
 * optional for single-parent clocks.  Always call .get_parent if it is
 * available and WARN if it is missing for multi-parent clocks.
 *
 * For single-parent clocks without .get_parent, first check to see if the
 * .parents array exists, and if so use it to avoid an expensive tree
 * traversal.  If .parents does not exist then walk the tree.
 */
static struct clk_core *__clk_init_parent(struct clk_core *core)
{
        struct clk_core *ret = NULL;
        u8 index;

        /* handle the trivial cases */

        if (!core->num_parents)
                goto out;

        if (core->num_parents == 1) {
                if (IS_ERR_OR_NULL(core->parent))
                        core->parent = clk_core_lookup(core->parent_names[0]);
                ret = core->parent;
                goto out;
        }

        if (!core->ops->get_parent) {
                WARN(!core->ops->get_parent,
                        "%s: multi-parent clocks must implement .get_parent\n",
                        __func__);
                goto out;
        }

        /*
         * Do our best to cache parent clocks in core->parents.  This prevents
         * unnecessary and expensive lookups.  We don't set core->parent here;
         * that is done by the calling function.
         */

        index = core->ops->get_parent(core->hw);

        if (!core->parents)
                core->parents =
                        kcalloc(core->num_parents, sizeof(struct clk *),
                                        GFP_KERNEL);

        ret = clk_core_get_parent_by_index(core, index);

out:
        return ret;
}

static void clk_core_reparent(struct clk_core *core,
                                  struct clk_core *new_parent)
{
        clk_reparent(core, new_parent);
        __clk_recalc_accuracies(core);
        __clk_recalc_rates(core, POST_RATE_CHANGE);
}

void clk_hw_reparent(struct clk_hw *hw, struct clk_hw *new_parent)
{
        if (!hw)
                return;

        clk_core_reparent(hw->core, !new_parent ? NULL : new_parent->core);
}

/**
 * clk_has_parent - check if a clock is a possible parent for another
 * @clk: clock source
 * @parent: parent clock source
 *
 * This function can be used in drivers that need to check that a clock can be
 * the parent of another without actually changing the parent.
 *
 * Returns true if @parent is a possible parent for @clk, false otherwise.
 */
bool clk_has_parent(struct clk *clk, struct clk *parent)
{
        struct clk_core *core, *parent_core;
        unsigned int i;

        /* NULL clocks should be nops, so return success if either is NULL. */
        if (!clk || !parent)
                return true;

        core = clk->core;
        parent_core = parent->core;

        /* Optimize for the case where the parent is already the parent. */
        if (core->parent == parent_core)
                return true;

        for (i = 0; i < core->num_parents; i++)
                if (strcmp(core->parent_names[i], parent_core->name) == 0)
                        return true;

        return false;
}
EXPORT_SYMBOL_GPL(clk_has_parent);

static int clk_core_set_parent(struct clk_core *core, struct clk_core *parent)
{
        int ret = 0;
        int p_index = 0;
        unsigned long p_rate = 0;

        if (!core)
                return 0;

        /* prevent racing with updates to the clock topology */
        clk_prepare_lock();

        if (core->parent == parent)
                goto out;

        /* verify ops for for multi-parent clks */
        if ((core->num_parents > 1) && (!core->ops->set_parent)) {
                ret = -ENOSYS;
                goto out;
        }

        /* check that we are allowed to re-parent if the clock is in use */
        if ((core->flags & CLK_SET_PARENT_GATE) && core->prepare_count) {
                ret = -EBUSY;
                goto out;
        }

        /* try finding the new parent index */
        if (parent) {
                p_index = clk_fetch_parent_index(core, parent);
                p_rate = parent->rate;
                if (p_index < 0) {
                        pr_debug("%s: clk %s can not be parent of clk %s\n",
                                        __func__, parent->name, core->name);
                        ret = p_index;
                        goto out;
                }
        }

        /* propagate PRE_RATE_CHANGE notifications */
        ret = __clk_speculate_rates(core, p_rate);

        /* abort if a driver objects */
        if (ret & NOTIFY_STOP_MASK)
                goto out;

        /* do the re-parent */
        ret = __clk_set_parent(core, parent, p_index);

        /* propagate rate an accuracy recalculation accordingly */
        if (ret) {
                __clk_recalc_rates(core, ABORT_RATE_CHANGE);
        } else {
                __clk_recalc_rates(core, POST_RATE_CHANGE);
                __clk_recalc_accuracies(core);
        }

out:
        clk_prepare_unlock();

        return ret;
}

/**
 * clk_set_parent - switch the parent of a mux clk
 * @clk: the mux clk whose input we are switching
 * @parent: the new input to clk
 *
 * Re-parent clk to use parent as its new input source.  If clk is in
 * prepared state, the clk will get enabled for the duration of this call. If
 * that's not acceptable for a specific clk (Eg: the consumer can't handle
 * that, the reparenting is glitchy in hardware, etc), use the
 * CLK_SET_PARENT_GATE flag to allow reparenting only when clk is unprepared.
 *
 * After successfully changing clk's parent clk_set_parent will update the
 * clk topology, sysfs topology and propagate rate recalculation via
 * __clk_recalc_rates.
 *
 * Returns 0 on success, -EERROR otherwise.
 */
int clk_set_parent(struct clk *clk, struct clk *parent)
{
        if (!clk)
                return 0;

        return clk_core_set_parent(clk->core, parent ? parent->core : NULL);
}
EXPORT_SYMBOL_GPL(clk_set_parent);

/**
 * clk_set_phase - adjust the phase shift of a clock signal
 * @clk: clock signal source
 * @degrees: number of degrees the signal is shifted
 *
 * Shifts the phase of a clock signal by the specified
 * degrees. Returns 0 on success, -EERROR otherwise.
 *
 * This function makes no distinction about the input or reference
 * signal that we adjust the clock signal phase against. For example
 * phase locked-loop clock signal generators we may shift phase with
 * respect to feedback clock signal input, but for other cases the
 * clock phase may be shifted with respect to some other, unspecified
 * signal.
 *
 * Additionally the concept of phase shift does not propagate through
 * the clock tree hierarchy, which sets it apart from clock rates and
 * clock accuracy. A parent clock phase attribute does not have an
 * impact on the phase attribute of a child clock.
 */
int clk_set_phase(struct clk *clk, int degrees)
{
        int ret = -EINVAL;

        if (!clk)
                return 0;

        /* sanity check degrees */
        degrees %= 360;
        if (degrees < 0)
                degrees += 360;

        clk_prepare_lock();

        /* bail early if nothing to do */
        if (degrees == clk->core->phase)
                goto out;

        trace_clk_set_phase(clk->core, degrees);

        if (clk->core->ops->set_phase)
                ret = clk->core->ops->set_phase(clk->core->hw, degrees);

        trace_clk_set_phase_complete(clk->core, degrees);

        if (!ret)
                clk->core->phase = degrees;

out:
        clk_prepare_unlock();

        return ret;
}
EXPORT_SYMBOL_GPL(clk_set_phase);

static int clk_core_get_phase(struct clk_core *core)
{
        int ret;

        clk_prepare_lock();
        ret = core->phase;
        clk_prepare_unlock();

        return ret;
}

/**
 * clk_get_phase - return the phase shift of a clock signal
 * @clk: clock signal source
 *
 * Returns the phase shift of a clock node in degrees, otherwise returns
 * -EERROR.
 */
int clk_get_phase(struct clk *clk)
{
        if (!clk)
                return 0;

        return clk_core_get_phase(clk->core);
}
EXPORT_SYMBOL_GPL(clk_get_phase);

/**
 * clk_is_match - check if two clk's point to the same hardware clock
 * @p: clk compared against q
 * @q: clk compared against p
 *
 * Returns true if the two struct clk pointers both point to the same hardware
 * clock node. Put differently, returns true if struct clk *p and struct clk *q
 * share the same struct clk_core object.
 *
 * Returns false otherwise. Note that two NULL clks are treated as matching.
 */
bool clk_is_match(const struct clk *p, const struct clk *q)
{
        /* trivial case: identical struct clk's or both NULL */
        if (p == q)
                return true;

        /* true if clk->core pointers match. Avoid derefing garbage */
        if (!IS_ERR_OR_NULL(p) && !IS_ERR_OR_NULL(q))
                if (p->core == q->core)
                        return true;

        return false;
}
EXPORT_SYMBOL_GPL(clk_is_match);

/***        debugfs support        ***/

#ifdef CONFIG_DEBUG_FS
#include <linux/debugfs.h>

static struct dentry *rootdir;
static int inited = 0;
static DEFINE_MUTEX(clk_debug_lock);
static HLIST_HEAD(clk_debug_list);

static struct hlist_head *all_lists[] = {
        &clk_root_list,
        &clk_orphan_list,
        NULL,
};

static struct hlist_head *orphan_list[] = {
        &clk_orphan_list,
        NULL,
};

static void clk_summary_show_one(struct seq_file *s, struct clk_core *c,
                                 int level)
{
        if (!c)
                return;

        seq_printf(s, "%*s%-*s %11d %12d %11lu %10lu %-3d\n",
                   level * 3 + 1, "",
                   30 - level * 3, c->name,
                   c->enable_count, c->prepare_count, clk_core_get_rate(c),
                   clk_core_get_accuracy(c), clk_core_get_phase(c));
}

static void clk_summary_show_subtree(struct seq_file *s, struct clk_core *c,
                                     int level)
{
        struct clk_core *child;

        if (!c)
                return;

        clk_summary_show_one(s, c, level);

        hlist_for_each_entry(child, &c->children, child_node)
                clk_summary_show_subtree(s, child, level + 1);
}

static int clk_summary_show(struct seq_file *s, void *data)
{
        struct clk_core *c;
        struct hlist_head **lists = (struct hlist_head **)s->private;

        seq_puts(s, "   clock                         enable_cnt  prepare_cnt        rate   accuracy   phase\n");
        seq_puts(s, "----------------------------------------------------------------------------------------\n");

        clk_prepare_lock();

        for (; *lists; lists++)
                hlist_for_each_entry(c, *lists, child_node)
                        clk_summary_show_subtree(s, c, 0);

        clk_prepare_unlock();

        return 0;
}


static int clk_summary_open(struct inode *inode, struct file *file)
{
        return single_open(file, clk_summary_show, inode->i_private);
}

static const struct file_operations clk_summary_fops = {
        .open           = clk_summary_open,
        .read           = seq_read,
        .llseek         = seq_lseek,
        .release        = single_release,
};

static void clk_dump_one(struct seq_file *s, struct clk_core *c, int level)
{
        if (!c)
                return;

        /* This should be JSON format, i.e. elements separated with a comma */
        seq_printf(s, "\"%s\": { ", c->name);
        seq_printf(s, "\"enable_count\": %d,", c->enable_count);
        seq_printf(s, "\"prepare_count\": %d,", c->prepare_count);
        seq_printf(s, "\"rate\": %lu,", clk_core_get_rate(c));
        seq_printf(s, "\"accuracy\": %lu,", clk_core_get_accuracy(c));
        seq_printf(s, "\"phase\": %d", clk_core_get_phase(c));
}

static void clk_dump_subtree(struct seq_file *s, struct clk_core *c, int level)
{
        struct clk_core *child;

        if (!c)
                return;

        clk_dump_one(s, c, level);

        hlist_for_each_entry(child, &c->children, child_node) {
                seq_printf(s, ",");
                clk_dump_subtree(s, child, level + 1);
        }

        seq_printf(s, "}");
}

static int clk_dump(struct seq_file *s, void *data)
{
        struct clk_core *c;
        bool first_node = true;
        struct hlist_head **lists = (struct hlist_head **)s->private;

        seq_printf(s, "{");

        clk_prepare_lock();

        for (; *lists; lists++) {
                hlist_for_each_entry(c, *lists, child_node) {
                        if (!first_node)
                                seq_puts(s, ",");
                        first_node = false;
                        clk_dump_subtree(s, c, 0);
                }
        }

        clk_prepare_unlock();

        seq_puts(s, "}\n");
        return 0;
}


static int clk_dump_open(struct inode *inode, struct file *file)
{
        return single_open(file, clk_dump, inode->i_private);
}

static const struct file_operations clk_dump_fops = {
        .open           = clk_dump_open,
        .read           = seq_read,
        .llseek         = seq_lseek,
        .release        = single_release,
};

static int clk_debug_create_one(struct clk_core *core, struct dentry *pdentry)
{
        struct dentry *d;
        int ret = -ENOMEM;

        if (!core || !pdentry) {
                ret = -EINVAL;
                goto out;
        }

        d = debugfs_create_dir(core->name, pdentry);
        if (!d)
                goto out;

        core->dentry = d;

        d = debugfs_create_u32("clk_rate", S_IRUGO, core->dentry,
                        (u32 *)&core->rate);
        if (!d)
                goto err_out;

        d = debugfs_create_u32("clk_accuracy", S_IRUGO, core->dentry,
                        (u32 *)&core->accuracy);
        if (!d)
                goto err_out;

        d = debugfs_create_u32("clk_phase", S_IRUGO, core->dentry,
                        (u32 *)&core->phase);
        if (!d)
                goto err_out;

        d = debugfs_create_x32("clk_flags", S_IRUGO, core->dentry,
                        (u32 *)&core->flags);
        if (!d)
                goto err_out;

        d = debugfs_create_u32("clk_prepare_count", S_IRUGO, core->dentry,
                        (u32 *)&core->prepare_count);
        if (!d)
                goto err_out;

        d = debugfs_create_u32("clk_enable_count", S_IRUGO, core->dentry,
                        (u32 *)&core->enable_count);
        if (!d)
                goto err_out;

        d = debugfs_create_u32("clk_notifier_count", S_IRUGO, core->dentry,
                        (u32 *)&core->notifier_count);
        if (!d)
                goto err_out;

        if (core->ops->debug_init) {
                ret = core->ops->debug_init(core->hw, core->dentry);
                if (ret)
                        goto err_out;
        }

        ret = 0;
        goto out;

err_out:
        debugfs_remove_recursive(core->dentry);
        core->dentry = NULL;
out:
        return ret;
}

/**
 * clk_debug_register - add a clk node to the debugfs clk directory
 * @core: the clk being added to the debugfs clk directory
 *
 * Dynamically adds a clk to the debugfs clk directory if debugfs has been
 * initialized.  Otherwise it bails out early since the debugfs clk directory
 * will be created lazily by clk_debug_init as part of a late_initcall.
 */
static int clk_debug_register(struct clk_core *core)
{
        int ret = 0;

        mutex_lock(&clk_debug_lock);
        hlist_add_head(&core->debug_node, &clk_debug_list);

        if (!inited)
                goto unlock;

        ret = clk_debug_create_one(core, rootdir);
unlock:
        mutex_unlock(&clk_debug_lock);

        return ret;
}

 /**
 * clk_debug_unregister - remove a clk node from the debugfs clk directory
 * @core: the clk being removed from the debugfs clk directory
 *
 * Dynamically removes a clk and all its child nodes from the
 * debugfs clk directory if clk->dentry points to debugfs created by
 * clk_debug_register in __clk_init.
 */
static void clk_debug_unregister(struct clk_core *core)
{
        mutex_lock(&clk_debug_lock);
        hlist_del_init(&core->debug_node);
        debugfs_remove_recursive(core->dentry);
        core->dentry = NULL;
        mutex_unlock(&clk_debug_lock);
}

struct dentry *clk_debugfs_add_file(struct clk_hw *hw, char *name, umode_t mode,
                                void *data, const struct file_operations *fops)
{
        struct dentry *d = NULL;

        if (hw->core->dentry)
                d = debugfs_create_file(name, mode, hw->core->dentry, data,
                                        fops);

        return d;
}
EXPORT_SYMBOL_GPL(clk_debugfs_add_file);

/**
 * clk_debug_init - lazily populate the debugfs clk directory
 *
 * clks are often initialized very early during boot before memory can be
 * dynamically allocated and well before debugfs is setup. This function
 * populates the debugfs clk directory once at boot-time when we know that
 * debugfs is setup. It should only be called once at boot-time, all other clks
 * added dynamically will be done so with clk_debug_register.
 */
static int __init clk_debug_init(void)
{
        struct clk_core *core;
        struct dentry *d;

        rootdir = debugfs_create_dir("clk", NULL);

        if (!rootdir)
                return -ENOMEM;

        d = debugfs_create_file("clk_summary", S_IRUGO, rootdir, &all_lists,
                                &clk_summary_fops);
        if (!d)
                return -ENOMEM;

        d = debugfs_create_file("clk_dump", S_IRUGO, rootdir, &all_lists,
                                &clk_dump_fops);
        if (!d)
                return -ENOMEM;

        d = debugfs_create_file("clk_orphan_summary", S_IRUGO, rootdir,
                                &orphan_list, &clk_summary_fops);
        if (!d)
                return -ENOMEM;

        d = debugfs_create_file("clk_orphan_dump", S_IRUGO, rootdir,
                                &orphan_list, &clk_dump_fops);
        if (!d)
                return -ENOMEM;

        mutex_lock(&clk_debug_lock);
        hlist_for_each_entry(core, &clk_debug_list, debug_node)
                clk_debug_create_one(core, rootdir);

        inited = 1;
        mutex_unlock(&clk_debug_lock);

        return 0;
}
late_initcall(clk_debug_init);
#else
static inline int clk_debug_register(struct clk_core *core) { return 0; }
static inline void clk_debug_reparent(struct clk_core *core,
                                      struct clk_core *new_parent)
{
}
static inline void clk_debug_unregister(struct clk_core *core)
{
}
#endif

/**
 * __clk_init - initialize the data structures in a struct clk
 * @dev:        device initializing this clk, placeholder for now
 * @clk:        clk being initialized
 *
 * Initializes the lists in struct clk_core, queries the hardware for the
 * parent and rate and sets them both.
 */
static int __clk_init(struct device *dev, struct clk *clk_user)
{
        int i, ret = 0;
        struct clk_core *orphan;
        struct hlist_node *tmp2;
        struct clk_core *core;
        unsigned long rate;

        if (!clk_user)
                return -EINVAL;

        core = clk_user->core;

        clk_prepare_lock();

        /* check to see if a clock with this name is already registered */
        if (clk_core_lookup(core->name)) {
                pr_debug("%s: clk %s already initialized\n",
                                __func__, core->name);
                ret = -EEXIST;
                goto out;
        }

        /* check that clk_ops are sane.  See Documentation/clk.txt */
        if (core->ops->set_rate &&
            !((core->ops->round_rate || core->ops->determine_rate) &&
              core->ops->recalc_rate)) {
                pr_warning("%s: %s must implement .round_rate or .determine_rate in addition to .recalc_rate\n",
                                __func__, core->name);
                ret = -EINVAL;
                goto out;
        }

        if (core->ops->set_parent && !core->ops->get_parent) {
                pr_warning("%s: %s must implement .get_parent & .set_parent\n",
                                __func__, core->name);
                ret = -EINVAL;
                goto out;
        }

        if (core->ops->set_rate_and_parent &&
                        !(core->ops->set_parent && core->ops->set_rate)) {
                pr_warn("%s: %s must implement .set_parent & .set_rate\n",
                                __func__, core->name);
                ret = -EINVAL;
                goto out;
        }

        /* throw a WARN if any entries in parent_names are NULL */
        for (i = 0; i < core->num_parents; i++)
                WARN(!core->parent_names[i],
                                "%s: invalid NULL in %s's .parent_names\n",
                                __func__, core->name);

        /*
         * Allocate an array of struct clk *'s to avoid unnecessary string
         * look-ups of clk's possible parents.  This can fail for clocks passed
         * in to clk_init during early boot; thus any access to core->parents[]
         * must always check for a NULL pointer and try to populate it if
         * necessary.
         *
         * If core->parents is not NULL we skip this entire block.  This allows
         * for clock drivers to statically initialize core->parents.
         */
        if (core->num_parents > 1 && !core->parents) {
                core->parents = kcalloc(core->num_parents, sizeof(struct clk *),
                                        GFP_KERNEL);
                /*
                 * clk_core_lookup returns NULL for parents that have not been
                 * clk_init'd; thus any access to clk->parents[] must check
                 * for a NULL pointer.  We can always perform lazy lookups for
                 * missing parents later on.
                 */
                if (core->parents)
                        for (i = 0; i < core->num_parents; i++)
                                core->parents[i] =
                                        clk_core_lookup(core->parent_names[i]);
        }

        core->parent = __clk_init_parent(core);

        /*
         * Populate core->parent if parent has already been __clk_init'd.  If
         * parent has not yet been __clk_init'd then place clk in the orphan
         * list.  If clk has set the CLK_IS_ROOT flag then place it in the root
         * clk list.
         *
         * Every time a new clk is clk_init'd then we walk the list of orphan
         * clocks and re-parent any that are children of the clock currently
         * being clk_init'd.
         */
        if (core->parent) {
                hlist_add_head(&core->child_node,
                                &core->parent->children);
                core->orphan = core->parent->orphan;
        } else if (core->flags & CLK_IS_ROOT) {
                hlist_add_head(&core->child_node, &clk_root_list);
                core->orphan = false;
        } else {
                hlist_add_head(&core->child_node, &clk_orphan_list);
                core->orphan = true;
        }

        /*
         * Set clk's accuracy.  The preferred method is to use
         * .recalc_accuracy. For simple clocks and lazy developers the default
         * fallback is to use the parent's accuracy.  If a clock doesn't have a
         * parent (or is orphaned) then accuracy is set to zero (perfect
         * clock).
         */
        if (core->ops->recalc_accuracy)
                core->accuracy = core->ops->recalc_accuracy(core->hw,
                                        __clk_get_accuracy(core->parent));
        else if (core->parent)
                core->accuracy = core->parent->accuracy;
        else
                core->accuracy = 0;

        /*
         * Set clk's phase.
         * Since a phase is by definition relative to its parent, just
         * query the current clock phase, or just assume it's in phase.
         */
        if (core->ops->get_phase)
                core->phase = core->ops->get_phase(core->hw);
        else
                core->phase = 0;

        /*
         * Set clk's rate.  The preferred method is to use .recalc_rate.  For
         * simple clocks and lazy developers the default fallback is to use the
         * parent's rate.  If a clock doesn't have a parent (or is orphaned)
         * then rate is set to zero.
         */
        if (core->ops->recalc_rate)
                rate = core->ops->recalc_rate(core->hw,
                                clk_core_get_rate_nolock(core->parent));
        else if (core->parent)
                rate = core->parent->rate;
        else
                rate = 0;
        core->rate = core->req_rate = rate;

        /*
         * walk the list of orphan clocks and reparent any that are children of
         * this clock
         */
        hlist_for_each_entry_safe(orphan, tmp2, &clk_orphan_list, child_node) {
                if (orphan->num_parents && orphan->ops->get_parent) {
                        i = orphan->ops->get_parent(orphan->hw);
                        if (i >= 0 && i < orphan->num_parents &&
                            !strcmp(core->name, orphan->parent_names[i]))
                                clk_core_reparent(orphan, core);
                        continue;
                }

                for (i = 0; i < orphan->num_parents; i++)
                        if (!strcmp(core->name, orphan->parent_names[i])) {
                                clk_core_reparent(orphan, core);
                                break;
                        }
         }

        /*
         * optional platform-specific magic
         *
         * The .init callback is not used by any of the basic clock types, but
         * exists for weird hardware that must perform initialization magic.
         * Please consider other ways of solving initialization problems before
         * using this callback, as its use is discouraged.
         */
        if (core->ops->init)
                core->ops->init(core->hw);

        kref_init(&core->ref);
out:
        clk_prepare_unlock();

        if (!ret)
                clk_debug_register(core);

        return ret;
}

struct clk *__clk_create_clk(struct clk_hw *hw, const char *dev_id,
                             const char *con_id)
{
        struct clk *clk;

        /* This is to allow this function to be chained to others */
        if (!hw || IS_ERR(hw))
                return (struct clk *) hw;

        clk = kzalloc(sizeof(*clk), GFP_KERNEL);
        if (!clk)
                return ERR_PTR(-ENOMEM);

        clk->core = hw->core;
        clk->dev_id = dev_id;
        clk->con_id = con_id;
        clk->max_rate = ULONG_MAX;

        clk_prepare_lock();
        hlist_add_head(&clk->clks_node, &hw->core->clks);
        clk_prepare_unlock();

        return clk;
}

void __clk_free_clk(struct clk *clk)
{
        clk_prepare_lock();
        hlist_del(&clk->clks_node);
        clk_prepare_unlock();

        kfree(clk);
}

/**
 * clk_register - allocate a new clock, register it and return an opaque cookie
 * @dev: device that is registering this clock
 * @hw: link to hardware-specific clock data
 *
 * clk_register is the primary interface for populating the clock tree with new
 * clock nodes.  It returns a pointer to the newly allocated struct clk which
 * cannot be dereferenced by driver code but may be used in conjunction with the
 * rest of the clock API.  In the event of an error clk_register will return an
 * error code; drivers must test for an error code after calling clk_register.
 */
struct clk *clk_register(struct device *dev, struct clk_hw *hw)
{
        int i, ret;
        struct clk_core *core;

        core = kzalloc(sizeof(*core), GFP_KERNEL);
        if (!core) {
                ret = -ENOMEM;
                goto fail_out;
        }

        core->name = kstrdup_const(hw->init->name, GFP_KERNEL);
        if (!core->name) {
                ret = -ENOMEM;
                goto fail_name;
        }
        core->ops = hw->init->ops;
        if (dev && dev->driver)
                core->owner = dev->driver->owner;
        core->hw = hw;
        core->flags = hw->init->flags;
        core->num_parents = hw->init->num_parents;
        core->min_rate = 0;
        core->max_rate = ULONG_MAX;
        hw->core = core;

        /* allocate local copy in case parent_names is __initdata */
        core->parent_names = kcalloc(core->num_parents, sizeof(char *),
                                        GFP_KERNEL);

        if (!core->parent_names) {
                ret = -ENOMEM;
                goto fail_parent_names;
        }


        /* copy each string name in case parent_names is __initdata */
        for (i = 0; i < core->num_parents; i++) {
                core->parent_names[i] = kstrdup_const(hw->init->parent_names[i],
                                                GFP_KERNEL);
                if (!core->parent_names[i]) {
                        ret = -ENOMEM;
                        goto fail_parent_names_copy;
                }
        }

        INIT_HLIST_HEAD(&core->clks);

        hw->clk = __clk_create_clk(hw, NULL, NULL);
        if (IS_ERR(hw->clk)) {
                ret = PTR_ERR(hw->clk);
                goto fail_parent_names_copy;
        }

        ret = __clk_init(dev, hw->clk);
        if (!ret)
                return hw->clk;

        __clk_free_clk(hw->clk);
        hw->clk = NULL;

fail_parent_names_copy:
        while (--i >= 0)
                kfree_const(core->parent_names[i]);
        kfree(core->parent_names);
fail_parent_names:
        kfree_const(core->name);
fail_name:
        kfree(core);
fail_out:
        return ERR_PTR(ret);
}
EXPORT_SYMBOL_GPL(clk_register);

/* Free memory allocated for a clock. */
static void __clk_release(struct kref *ref)
{
        struct clk_core *core = container_of(ref, struct clk_core, ref);
        int i = core->num_parents;

        lockdep_assert_held(&prepare_lock);

        kfree(core->parents);
        while (--i >= 0)
                kfree_const(core->parent_names[i]);

        kfree(core->parent_names);
        kfree_const(core->name);
        kfree(core);
}

/*
 * Empty clk_ops for unregistered clocks. These are used temporarily
 * after clk_unregister() was called on a clock and until last clock
 * consumer calls clk_put() and the struct clk object is freed.
 */
static int clk_nodrv_prepare_enable(struct clk_hw *hw)
{
        return -ENXIO;
}

static void clk_nodrv_disable_unprepare(struct clk_hw *hw)
{
        WARN_ON_ONCE(1);
}

static int clk_nodrv_set_rate(struct clk_hw *hw, unsigned long rate,
                                        unsigned long parent_rate)
{
        return -ENXIO;
}

static int clk_nodrv_set_parent(struct clk_hw *hw, u8 index)
{
        return -ENXIO;
}

static const struct clk_ops clk_nodrv_ops = {
        .enable         = clk_nodrv_prepare_enable,
        .disable        = clk_nodrv_disable_unprepare,
        .prepare        = clk_nodrv_prepare_enable,
        .unprepare      = clk_nodrv_disable_unprepare,
        .set_rate       = clk_nodrv_set_rate,
        .set_parent     = clk_nodrv_set_parent,
};

/**
 * clk_unregister - unregister a currently registered clock
 * @clk: clock to unregister
 */
void clk_unregister(struct clk *clk)
{
        unsigned long flags;

        if (!clk || WARN_ON_ONCE(IS_ERR(clk)))
                return;

        clk_debug_unregister(clk->core);

        clk_prepare_lock();

        if (clk->core->ops == &clk_nodrv_ops) {
                pr_err("%s: unregistered clock: %s\n", __func__,
                       clk->core->name);
                return;
        }
        /*
         * Assign empty clock ops for consumers that might still hold
         * a reference to this clock.
         */
        flags = clk_enable_lock();
        clk->core->ops = &clk_nodrv_ops;
        clk_enable_unlock(flags);

        if (!hlist_empty(&clk->core->children)) {
                struct clk_core *child;
                struct hlist_node *t;

                /* Reparent all children to the orphan list. */
                hlist_for_each_entry_safe(child, t, &clk->core->children,
                                          child_node)
                        clk_core_set_parent(child, NULL);
        }

        hlist_del_init(&clk->core->child_node);

        if (clk->core->prepare_count)
                pr_warn("%s: unregistering prepared clock: %s\n",
                                        __func__, clk->core->name);
        kref_put(&clk->core->ref, __clk_release);

        clk_prepare_unlock();
}
EXPORT_SYMBOL_GPL(clk_unregister);

static void devm_clk_release(struct device *dev, void *res)
{
        clk_unregister(*(struct clk **)res);
}

/**
 * devm_clk_register - resource managed clk_register()
 * @dev: device that is registering this clock
 * @hw: link to hardware-specific clock data
 *
 * Managed clk_register(). Clocks returned from this function are
 * automatically clk_unregister()ed on driver detach. See clk_register() for
 * more information.
 */
struct clk *devm_clk_register(struct device *dev, struct clk_hw *hw)
{
        struct clk *clk;
        struct clk **clkp;

        clkp = devres_alloc(devm_clk_release, sizeof(*clkp), GFP_KERNEL);
        if (!clkp)
                return ERR_PTR(-ENOMEM);

        clk = clk_register(dev, hw);
        if (!IS_ERR(clk)) {
                *clkp = clk;
                devres_add(dev, clkp);
        } else {
                devres_free(clkp);
        }

        return clk;
}
EXPORT_SYMBOL_GPL(devm_clk_register);

static int devm_clk_match(struct device *dev, void *res, void *data)
{
        struct clk *c = res;
        if (WARN_ON(!c))
                return 0;
        return c == data;
}

/**
 * devm_clk_unregister - resource managed clk_unregister()
 * @clk: clock to unregister
 *
 * Deallocate a clock allocated with devm_clk_register(). Normally
 * this function will not need to be called and the resource management
 * code will ensure that the resource is freed.
 */
void devm_clk_unregister(struct device *dev, struct clk *clk)
{
        WARN_ON(devres_release(dev, devm_clk_release, devm_clk_match, clk));
}
EXPORT_SYMBOL_GPL(devm_clk_unregister);

/*
 * clkdev helpers
 */
int __clk_get(struct clk *clk)
{
        struct clk_core *core = !clk ? NULL : clk->core;

        if (core) {
                if (!try_module_get(core->owner))
                        return 0;

                kref_get(&core->ref);
        }
        return 1;
}

void __clk_put(struct clk *clk)
{
        struct module *owner;

        if (!clk || WARN_ON_ONCE(IS_ERR(clk)))
                return;

        clk_prepare_lock();

        hlist_del(&clk->clks_node);
        if (clk->min_rate > clk->core->req_rate ||
            clk->max_rate < clk->core->req_rate)
                clk_core_set_rate_nolock(clk->core, clk->core->req_rate);

        owner = clk->core->owner;
        kref_put(&clk->core->ref, __clk_release);

        clk_prepare_unlock();

        module_put(owner);

        kfree(clk);
}

/***        clk rate change notifiers        ***/

/**
 * clk_notifier_register - add a clk rate change notifier
 * @clk: struct clk * to watch
 * @nb: struct notifier_block * with callback info
 *
 * Request notification when clk's rate changes.  This uses an SRCU
 * notifier because we want it to block and notifier unregistrations are
 * uncommon.  The callbacks associated with the notifier must not
 * re-enter into the clk framework by calling any top-level clk APIs;
 * this will cause a nested prepare_lock mutex.
 *
 * In all notification cases cases (pre, post and abort rate change) the
 * original clock rate is passed to the callback via struct
 * clk_notifier_data.old_rate and the new frequency is passed via struct
 * clk_notifier_data.new_rate.
 *
 * clk_notifier_register() must be called from non-atomic context.
 * Returns -EINVAL if called with null arguments, -ENOMEM upon
 * allocation failure; otherwise, passes along the return value of
 * srcu_notifier_chain_register().
 */
int clk_notifier_register(struct clk *clk, struct notifier_block *nb)
{
        struct clk_notifier *cn;
        int ret = -ENOMEM;

        if (!clk || !nb)
                return -EINVAL;

        clk_prepare_lock();

        /* search the list of notifiers for this clk */
        list_for_each_entry(cn, &clk_notifier_list, node)
                if (cn->clk == clk)
                        break;

        /* if clk wasn't in the notifier list, allocate new clk_notifier */
        if (cn->clk != clk) {
                cn = kzalloc(sizeof(struct clk_notifier), GFP_KERNEL);
                if (!cn)
                        goto out;

                cn->clk = clk;
                srcu_init_notifier_head(&cn->notifier_head);

                list_add(&cn->node, &clk_notifier_list);
        }

        ret = srcu_notifier_chain_register(&cn->notifier_head, nb);

        clk->core->notifier_count++;

out:
        clk_prepare_unlock();

        return ret;
}
EXPORT_SYMBOL_GPL(clk_notifier_register);

/**
 * clk_notifier_unregister - remove a clk rate change notifier
 * @clk: struct clk *
 * @nb: struct notifier_block * with callback info
 *
 * Request no further notification for changes to 'clk' and frees memory
 * allocated in clk_notifier_register.
 *
 * Returns -EINVAL if called with null arguments; otherwise, passes
 * along the return value of srcu_notifier_chain_unregister().
 */
int clk_notifier_unregister(struct clk *clk, struct notifier_block *nb)
{
        struct clk_notifier *cn = NULL;
        int ret = -EINVAL;

        if (!clk || !nb)
                return -EINVAL;

        clk_prepare_lock();

        list_for_each_entry(cn, &clk_notifier_list, node)
                if (cn->clk == clk)
                        break;

        if (cn->clk == clk) {
                ret = srcu_notifier_chain_unregister(&cn->notifier_head, nb);

                clk->core->notifier_count--;

                /* XXX the notifier code should handle this better */
                if (!cn->notifier_head.head) {
                        srcu_cleanup_notifier_head(&cn->notifier_head);
                        list_del(&cn->node);
                        kfree(cn);
                }

        } else {
                ret = -ENOENT;
        }

        clk_prepare_unlock();

        return ret;
}
EXPORT_SYMBOL_GPL(clk_notifier_unregister);

#ifdef CONFIG_OF
/**
 * struct of_clk_provider - Clock provider registration structure
 * @link: Entry in global list of clock providers
 * @node: Pointer to device tree node of clock provider
 * @get: Get clock callback.  Returns NULL or a struct clk for the
 *       given clock specifier
 * @data: context pointer to be passed into @get callback
 */
struct of_clk_provider {
        struct list_head link;

        struct device_node *node;
        struct clk *(*get)(struct of_phandle_args *clkspec, void *data);
        void *data;
};

static const struct of_device_id __clk_of_table_sentinel
        __used __section(__clk_of_table_end);

static LIST_HEAD(of_clk_providers);
static DEFINE_MUTEX(of_clk_mutex);

struct clk *of_clk_src_simple_get(struct of_phandle_args *clkspec,
                                     void *data)
{
        return data;
}
EXPORT_SYMBOL_GPL(of_clk_src_simple_get);

struct clk *of_clk_src_onecell_get(struct of_phandle_args *clkspec, void *data)
{
        struct clk_onecell_data *clk_data = data;
        unsigned int idx = clkspec->args[0];

        if (idx >= clk_data->clk_num) {
                pr_err("%s: invalid clock index %u\n", __func__, idx);
                return ERR_PTR(-EINVAL);
        }

        return clk_data->clks[idx];
}
EXPORT_SYMBOL_GPL(of_clk_src_onecell_get);

/**
 * of_clk_add_provider() - Register a clock provider for a node
 * @np: Device node pointer associated with clock provider
 * @clk_src_get: callback for decoding clock
 * @data: context pointer for @clk_src_get callback.
 */
int of_clk_add_provider(struct device_node *np,
                        struct clk *(*clk_src_get)(struct of_phandle_args *clkspec,
                                                   void *data),
                        void *data)
{
        struct of_clk_provider *cp;
        int ret;

        cp = kzalloc(sizeof(struct of_clk_provider), GFP_KERNEL);
        if (!cp)
                return -ENOMEM;

        cp->node = of_node_get(np);
        cp->data = data;
        cp->get = clk_src_get;

        mutex_lock(&of_clk_mutex);
        list_add(&cp->link, &of_clk_providers);
        mutex_unlock(&of_clk_mutex);
        pr_debug("Added clock from %s\n", np->full_name);

        ret = of_clk_set_defaults(np, true);
        if (ret < 0)
                of_clk_del_provider(np);

        return ret;
}
EXPORT_SYMBOL_GPL(of_clk_add_provider);

/**
 * of_clk_del_provider() - Remove a previously registered clock provider
 * @np: Device node pointer associated with clock provider
 */
void of_clk_del_provider(struct device_node *np)
{
        struct of_clk_provider *cp;

        mutex_lock(&of_clk_mutex);
        list_for_each_entry(cp, &of_clk_providers, link) {
                if (cp->node == np) {
                        list_del(&cp->link);
                        of_node_put(cp->node);
                        kfree(cp);
                        break;
                }
        }
        mutex_unlock(&of_clk_mutex);
}
EXPORT_SYMBOL_GPL(of_clk_del_provider);

struct clk *__of_clk_get_from_provider(struct of_phandle_args *clkspec,
                                       const char *dev_id, const char *con_id)
{
        struct of_clk_provider *provider;
        struct clk *clk = ERR_PTR(-EPROBE_DEFER);

        if (!clkspec)
                return ERR_PTR(-EINVAL);

        /* Check if we have such a provider in our array */
        mutex_lock(&of_clk_mutex);
        list_for_each_entry(provider, &of_clk_providers, link) {
                if (provider->node == clkspec->np)
                        clk = provider->get(clkspec, provider->data);
                if (!IS_ERR(clk)) {
                        clk = __clk_create_clk(__clk_get_hw(clk), dev_id,
                                               con_id);

                        if (!IS_ERR(clk) && !__clk_get(clk)) {
                                __clk_free_clk(clk);
                                clk = ERR_PTR(-ENOENT);
                        }

                        break;
                }
        }
        mutex_unlock(&of_clk_mutex);

        return clk;
}

/**
 * of_clk_get_from_provider() - Lookup a clock from a clock provider
 * @clkspec: pointer to a clock specifier data structure
 *
 * This function looks up a struct clk from the registered list of clock
 * providers, an input is a clock specifier data structure as returned
 * from the of_parse_phandle_with_args() function call.
 */
struct clk *of_clk_get_from_provider(struct of_phandle_args *clkspec)
{
        return __of_clk_get_from_provider(clkspec, NULL, __func__);
}

int of_clk_get_parent_count(struct device_node *np)
{
        return of_count_phandle_with_args(np, "clocks", "#clock-cells");
}
EXPORT_SYMBOL_GPL(of_clk_get_parent_count);

const char *of_clk_get_parent_name(struct device_node *np, int index)
{
        struct of_phandle_args clkspec;
        struct property *prop;
        const char *clk_name;
        const __be32 *vp;
        u32 pv;
        int rc;
        int count;
        struct clk *clk;

        if (index < 0)
                return NULL;

        rc = of_parse_phandle_with_args(np, "clocks", "#clock-cells", index,
                                        &clkspec);
        if (rc)
                return NULL;

        index = clkspec.args_count ? clkspec.args[0] : 0;
        count = 0;

        /* if there is an indices property, use it to transfer the index
         * specified into an array offset for the clock-output-names property.
         */
        of_property_for_each_u32(clkspec.np, "clock-indices", prop, vp, pv) {
                if (index == pv) {
                        index = count;
                        break;
                }
                count++;
        }

        if (of_property_read_string_index(clkspec.np, "clock-output-names",
                                          index,
                                          &clk_name) < 0) {
                /*
                 * Best effort to get the name if the clock has been
                 * registered with the framework. If the clock isn't
                 * registered, we return the node name as the name of
                 * the clock as long as #clock-cells = 0.
                 */
                clk = of_clk_get_from_provider(&clkspec);
                if (IS_ERR(clk)) {
                        if (clkspec.args_count == 0)
                                clk_name = clkspec.np->name;
                        else
                                clk_name = NULL;
                } else {
                        clk_name = __clk_get_name(clk);
                        clk_put(clk);
                }
        }


        of_node_put(clkspec.np);
        return clk_name;
}
EXPORT_SYMBOL_GPL(of_clk_get_parent_name);

/**
 * of_clk_parent_fill() - Fill @parents with names of @np's parents and return
 * number of parents
 * @np: Device node pointer associated with clock provider
 * @parents: pointer to char array that hold the parents' names
 * @size: size of the @parents array
 *
 * Return: number of parents for the clock node.
 */
int of_clk_parent_fill(struct device_node *np, const char **parents,
                       unsigned int size)
{
        unsigned int i = 0;

        while (i < size && (parents[i] = of_clk_get_parent_name(np, i)) != NULL)
                i++;

        return i;
}
EXPORT_SYMBOL_GPL(of_clk_parent_fill);

struct clock_provider {
        of_clk_init_cb_t clk_init_cb;
        struct device_node *np;
        struct list_head node;
};

/*
 * This function looks for a parent clock. If there is one, then it
 * checks that the provider for this parent clock was initialized, in
 * this case the parent clock will be ready.
 */
static int parent_ready(struct device_node *np)
{
        int i = 0;

        while (true) {
                struct clk *clk = of_clk_get(np, i);

                /* this parent is ready we can check the next one */
                if (!IS_ERR(clk)) {
                        clk_put(clk);
                        i++;
                        continue;
                }

                /* at least one parent is not ready, we exit now */
                if (PTR_ERR(clk) == -EPROBE_DEFER)
                        return 0;

                /*
                 * Here we make assumption that the device tree is
                 * written correctly. So an error means that there is
                 * no more parent. As we didn't exit yet, then the
                 * previous parent are ready. If there is no clock
                 * parent, no need to wait for them, then we can
                 * consider their absence as being ready
                 */
                return 1;
        }
}

/**
 * of_clk_init() - Scan and init clock providers from the DT
 * @matches: array of compatible values and init functions for providers.
 *
 * This function scans the device tree for matching clock providers
 * and calls their initialization functions. It also does it by trying
 * to follow the dependencies.
 */
void __init of_clk_init(const struct of_device_id *matches)
{
        const struct of_device_id *match;
        struct device_node *np;
        struct clock_provider *clk_provider, *next;
        bool is_init_done;
        bool force = false;
        LIST_HEAD(clk_provider_list);

        if (!matches)
                matches = &__clk_of_table;

        /* First prepare the list of the clocks providers */
        for_each_matching_node_and_match(np, matches, &match) {
                struct clock_provider *parent;

                parent = kzalloc(sizeof(*parent), GFP_KERNEL);
                if (!parent) {
                        list_for_each_entry_safe(clk_provider, next,
                                                 &clk_provider_list, node) {
                                list_del(&clk_provider->node);
                                of_node_put(clk_provider->np);
                                kfree(clk_provider);
                        }
                        of_node_put(np);
                        return;
                }

                parent->clk_init_cb = match->data;
                parent->np = of_node_get(np);
                list_add_tail(&parent->node, &clk_provider_list);
        }

        while (!list_empty(&clk_provider_list)) {
                is_init_done = false;
                list_for_each_entry_safe(clk_provider, next,
                                        &clk_provider_list, node) {
                        if (force || parent_ready(clk_provider->np)) {

                                clk_provider->clk_init_cb(clk_provider->np);
                                of_clk_set_defaults(clk_provider->np, true);

                                list_del(&clk_provider->node);
                                of_node_put(clk_provider->np);
                                kfree(clk_provider);
                                is_init_done = true;
                        }
                }

                /*
                 * We didn't manage to initialize any of the
                 * remaining providers during the last loop, so now we
                 * initialize all the remaining ones unconditionally
                 * in case the clock parent was not mandatory
                 */
                if (!is_init_done)
                        force = true;
        }
}
#endif