drivers/clk/mvebu/clk-corediv.c

   1 /*
   2  * MVEBU Core divider clock
   3  *
   4  * Copyright (C) 2013 Marvell
   5  *
   6  * Ezequiel Garcia <ezequiel.garcia@free-electrons.com>
   7  *
   8  * This file is licensed under the terms of the GNU General Public
   9  * License version 2.  This program is licensed "as is" without any
  10  * warranty of any kind, whether express or implied.
  11  */
  12
  13 #include <linux/kernel.h>
  14 #include <linux/clk-provider.h>
  15 #include <linux/of_address.h>
  16 #include <linux/slab.h>
  17 #include <linux/delay.h>
  18 #include "common.h"
  19
  20 #define CORE_CLK_DIV_RATIO_MASK         0xff
  21 #define CORE_CLK_DIV_RATIO_RELOAD       BIT(8)
  22 #define CORE_CLK_DIV_ENABLE_OFFSET      24
  23 #define CORE_CLK_DIV_RATIO_OFFSET       0x8
  24
  25 struct clk_corediv_desc {
  26         unsigned int mask;
  27         unsigned int offset;
  28         unsigned int fieldbit;
  29 };
  30
  31 struct clk_corediv {
  32         struct clk_hw hw;
  33         void __iomem *reg;
  34         struct clk_corediv_desc desc;
  35         spinlock_t lock;
  36 };
  37
  38 static struct clk_onecell_data clk_data;
  39
  40 static const struct clk_corediv_desc mvebu_corediv_desc[] __initconst = {
  41         { .mask = 0x3f, .offset = 8, .fieldbit = 1 }, /* NAND clock */
  42 };
  43
  44 #define to_corediv_clk(p) container_of(p, struct clk_corediv, hw)
  45
  46 static int clk_corediv_is_enabled(struct clk_hw *hwclk)
  47 {
  48         struct clk_corediv *corediv = to_corediv_clk(hwclk);
  49         struct clk_corediv_desc *desc = &corediv->desc;
  50         u32 enable_mask = BIT(desc->fieldbit) << CORE_CLK_DIV_ENABLE_OFFSET;
  51
  52         return !!(readl(corediv->reg) & enable_mask);
  53 }
  54
  55 static int clk_corediv_enable(struct clk_hw *hwclk)
  56 {
  57         struct clk_corediv *corediv = to_corediv_clk(hwclk);
  58         struct clk_corediv_desc *desc = &corediv->desc;
  59         unsigned long flags = 0;
  60         u32 reg;
  61
  62         spin_lock_irqsave(&corediv->lock, flags);
  63
  64         reg = readl(corediv->reg);
  65         reg |= (BIT(desc->fieldbit) << CORE_CLK_DIV_ENABLE_OFFSET);
  66         writel(reg, corediv->reg);
  67
  68         spin_unlock_irqrestore(&corediv->lock, flags);
  69
  70         return 0;
  71 }
  72
  73 static void clk_corediv_disable(struct clk_hw *hwclk)
  74 {
  75         struct clk_corediv *corediv = to_corediv_clk(hwclk);
  76         struct clk_corediv_desc *desc = &corediv->desc;
  77         unsigned long flags = 0;
  78         u32 reg;
  79
  80         spin_lock_irqsave(&corediv->lock, flags);
  81
  82         reg = readl(corediv->reg);
  83         reg &= ~(BIT(desc->fieldbit) << CORE_CLK_DIV_ENABLE_OFFSET);
  84         writel(reg, corediv->reg);
  85
  86         spin_unlock_irqrestore(&corediv->lock, flags);
  87 }
  88
  89 static unsigned long clk_corediv_recalc_rate(struct clk_hw *hwclk,
  90                                          unsigned long parent_rate)
  91 {
  92         struct clk_corediv *corediv = to_corediv_clk(hwclk);
  93         struct clk_corediv_desc *desc = &corediv->desc;
  94         u32 reg, div;
  95
  96         reg = readl(corediv->reg + CORE_CLK_DIV_RATIO_OFFSET);
  97         div = (reg >> desc->offset) & desc->mask;
  98         return parent_rate / div;
  99 }
 100
 101 static long clk_corediv_round_rate(struct clk_hw *hwclk, unsigned long rate,
 102                                unsigned long *parent_rate)
 103 {
 104         /* Valid ratio are 1:4, 1:5, 1:6 and 1:8 */
 105         u32 div;
 106
 107         div = *parent_rate / rate;
 108         if (div < 4)
 109                 div = 4;
 110         else if (div > 6)
 111                 div = 8;
 112
 113         return *parent_rate / div;
 114 }
 115
 116 static int clk_corediv_set_rate(struct clk_hw *hwclk, unsigned long rate,
 117                             unsigned long parent_rate)
 118 {
 119         struct clk_corediv *corediv = to_corediv_clk(hwclk);
 120         struct clk_corediv_desc *desc = &corediv->desc;
 121         unsigned long flags = 0;
 122         u32 reg, div;
 123
 124         div = parent_rate / rate;
 125
 126         spin_lock_irqsave(&corediv->lock, flags);
 127
 128         /* Write new divider to the divider ratio register */
 129         reg = readl(corediv->reg + CORE_CLK_DIV_RATIO_OFFSET);
 130         reg &= ~(desc->mask << desc->offset);
 131         reg |= (div & desc->mask) << desc->offset;
 132         writel(reg, corediv->reg + CORE_CLK_DIV_RATIO_OFFSET);
 133
 134         /* Set reload-force for this clock */
 135         reg = readl(corediv->reg) | BIT(desc->fieldbit);
 136         writel(reg, corediv->reg);
 137
 138         /* Now trigger the clock update */
 139         reg = readl(corediv->reg) | CORE_CLK_DIV_RATIO_RELOAD;
 140         writel(reg, corediv->reg);
 141
 142         /*
 143          * Wait for clocks to settle down, and then clear all the
 144          * ratios request and the reload request.
 145          */
 146         udelay(1000);
 147         reg &= ~(CORE_CLK_DIV_RATIO_MASK | CORE_CLK_DIV_RATIO_RELOAD);
 148         writel(reg, corediv->reg);
 149         udelay(1000);
 150
 151         spin_unlock_irqrestore(&corediv->lock, flags);
 152
 153         return 0;
 154 }
 155
 156 static const struct clk_ops corediv_ops = {
 157         .enable = clk_corediv_enable,
 158         .disable = clk_corediv_disable,
 159         .is_enabled = clk_corediv_is_enabled,
 160         .recalc_rate = clk_corediv_recalc_rate,
 161         .round_rate = clk_corediv_round_rate,
 162         .set_rate = clk_corediv_set_rate,
 163 };
 164
 165 static void __init mvebu_corediv_clk_init(struct device_node *node)
 166 {
 167         struct clk_init_data init;
 168         struct clk_corediv *corediv;
 169         struct clk **clks;
 170         void __iomem *base;
 171         const char *parent_name;
 172         const char *clk_name;
 173         int i;
 174
 175         base = of_iomap(node, 0);
 176         if (WARN_ON(!base))
 177                 return;
 178
 179         parent_name = of_clk_get_parent_name(node, 0);
 180
 181         clk_data.clk_num = ARRAY_SIZE(mvebu_corediv_desc);
 182
 183         /* clks holds the clock array */
 184         clks = kcalloc(clk_data.clk_num, sizeof(struct clk *),
 185                                 GFP_KERNEL);
 186         if (WARN_ON(!clks))
 187                 goto err_unmap;
 188         /* corediv holds the clock specific array */
 189         corediv = kcalloc(clk_data.clk_num, sizeof(struct clk_corediv),
 190                                 GFP_KERNEL);
 191         if (WARN_ON(!corediv))
 192                 goto err_free_clks;
 193
 194         spin_lock_init(&corediv->lock);
 195
 196         for (i = 0; i < clk_data.clk_num; i++) {
 197                 of_property_read_string_index(node, "clock-output-names",
 198                                               i, &clk_name);
 199                 init.num_parents = 1;
 200                 init.parent_names = &parent_name;
 201                 init.name = clk_name;
 202                 init.ops = &corediv_ops;
 203                 init.flags = 0;
 204
 205                 corediv[i].desc = mvebu_corediv_desc[i];
 206                 corediv[i].reg = base;
 207                 corediv[i].hw.init = &init;
 208
 209                 clks[i] = clk_register(NULL, &corediv[i].hw);
 210                 WARN_ON(IS_ERR(clks[i]));
 211         }
 212
 213         clk_data.clks = clks;
 214         of_clk_add_provider(node, of_clk_src_onecell_get, &clk_data);
 215         return;
 216
 217 err_free_clks:
 218         kfree(clks);
 219 err_unmap:
 220         iounmap(base);
 221 }
 222 CLK_OF_DECLARE(mvebu_corediv_clk, "marvell,armada-370-corediv-clock",
 223                mvebu_corediv_clk_init);