drivers/reset/reset-lpc18xx.c

   1 /*
   2  * Reset driver for NXP LPC18xx/43xx Reset Generation Unit (RGU).
   3  *
   4  * Copyright (C) 2015 Joachim Eastwood <manabian@gmail.com>
   5  *
   6  * This program is free software; you can redistribute it and/or modify
   7  * it under the terms of the GNU General Public License version 2 as
   8  * published by the Free Software Foundation.
   9  *
  10  */
  11
  12 #include <linux/clk.h>
  13 #include <linux/delay.h>
  14 #include <linux/err.h>
  15 #include <linux/io.h>
  16 #include <linux/module.h>
  17 #include <linux/of.h>
  18 #include <linux/platform_device.h>
  19 #include <linux/reboot.h>
  20 #include <linux/reset-controller.h>
  21 #include <linux/spinlock.h>
  22
  23 /* LPC18xx RGU registers */
  24 #define LPC18XX_RGU_CTRL0               0x100
  25 #define LPC18XX_RGU_CTRL1               0x104
  26 #define LPC18XX_RGU_ACTIVE_STATUS0      0x150
  27 #define LPC18XX_RGU_ACTIVE_STATUS1      0x154
  28
  29 #define LPC18XX_RGU_RESETS_PER_REG      32
  30
  31 /* Internal reset outputs */
  32 #define LPC18XX_RGU_CORE_RST    0
  33 #define LPC43XX_RGU_M0SUB_RST   12
  34 #define LPC43XX_RGU_M0APP_RST   56
  35
  36 struct lpc18xx_rgu_data {
  37         struct reset_controller_dev rcdev;
  38         struct clk *clk_delay;
  39         struct clk *clk_reg;
  40         void __iomem *base;
  41         spinlock_t lock;
  42         u32 delay_us;
  43 };
  44
  45 #define to_rgu_data(p) container_of(p, struct lpc18xx_rgu_data, rcdev)
  46
  47 static void __iomem *rgu_base;
  48
  49 static int lpc18xx_rgu_restart(struct notifier_block *this, unsigned long mode,
  50                                void *cmd)
  51 {
  52         writel(BIT(LPC18XX_RGU_CORE_RST), rgu_base + LPC18XX_RGU_CTRL0);
  53         mdelay(2000);
  54
  55         pr_emerg("%s: unable to restart system\n", __func__);
  56
  57         return NOTIFY_DONE;
  58 }
  59
  60 static struct notifier_block lpc18xx_rgu_restart_nb = {
  61         .notifier_call = lpc18xx_rgu_restart,
  62         .priority = 192,
  63 };
  64
  65 /*
  66  * The LPC18xx RGU has mostly self-deasserting resets except for the
  67  * two reset lines going to the internal Cortex-M0 cores.
  68  *
  69  * To prevent the M0 core resets from accidentally getting deasserted
  70  * status register must be check and bits in control register set to
  71  * preserve the state.
  72  */
  73 static int lpc18xx_rgu_setclear_reset(struct reset_controller_dev *rcdev,
  74                                       unsigned long id, bool set)
  75 {
  76         struct lpc18xx_rgu_data *rc = to_rgu_data(rcdev);
  77         u32 stat_offset = LPC18XX_RGU_ACTIVE_STATUS0;
  78         u32 ctrl_offset = LPC18XX_RGU_CTRL0;
  79         unsigned long flags;
  80         u32 stat, rst_bit;
  81
  82         stat_offset += (id / LPC18XX_RGU_RESETS_PER_REG) * sizeof(u32);
  83         ctrl_offset += (id / LPC18XX_RGU_RESETS_PER_REG) * sizeof(u32);
  84         rst_bit = 1 << (id % LPC18XX_RGU_RESETS_PER_REG);
  85
  86         spin_lock_irqsave(&rc->lock, flags);
  87         stat = ~readl(rc->base + stat_offset);
  88         if (set)
  89                 writel(stat | rst_bit, rc->base + ctrl_offset);
  90         else
  91                 writel(stat & ~rst_bit, rc->base + ctrl_offset);
  92         spin_unlock_irqrestore(&rc->lock, flags);
  93
  94         return 0;
  95 }
  96
  97 static int lpc18xx_rgu_assert(struct reset_controller_dev *rcdev,
  98                               unsigned long id)
  99 {
 100         return lpc18xx_rgu_setclear_reset(rcdev, id, true);
 101 }
 102
 103 static int lpc18xx_rgu_deassert(struct reset_controller_dev *rcdev,
 104                                 unsigned long id)
 105 {
 106         return lpc18xx_rgu_setclear_reset(rcdev, id, false);
 107 }
 108
 109 /* Only M0 cores require explicit reset deassert */
 110 static int lpc18xx_rgu_reset(struct reset_controller_dev *rcdev,
 111                              unsigned long id)
 112 {
 113         struct lpc18xx_rgu_data *rc = to_rgu_data(rcdev);
 114
 115         lpc18xx_rgu_assert(rcdev, id);
 116         udelay(rc->delay_us);
 117
 118         switch (id) {
 119         case LPC43XX_RGU_M0SUB_RST:
 120         case LPC43XX_RGU_M0APP_RST:
 121                 lpc18xx_rgu_setclear_reset(rcdev, id, false);
 122         }
 123
 124         return 0;
 125 }
 126
 127 static int lpc18xx_rgu_status(struct reset_controller_dev *rcdev,
 128                               unsigned long id)
 129 {
 130         struct lpc18xx_rgu_data *rc = to_rgu_data(rcdev);
 131         u32 bit, offset = LPC18XX_RGU_ACTIVE_STATUS0;
 132
 133         offset += (id / LPC18XX_RGU_RESETS_PER_REG) * sizeof(u32);
 134         bit = 1 << (id % LPC18XX_RGU_RESETS_PER_REG);
 135
 136         return !(readl(rc->base + offset) & bit);
 137 }
 138
 139 static struct reset_control_ops lpc18xx_rgu_ops = {
 140         .reset          = lpc18xx_rgu_reset,
 141         .assert         = lpc18xx_rgu_assert,
 142         .deassert       = lpc18xx_rgu_deassert,
 143         .status         = lpc18xx_rgu_status,
 144 };
 145
 146 static int lpc18xx_rgu_probe(struct platform_device *pdev)
 147 {
 148         struct lpc18xx_rgu_data *rc;
 149         struct resource *res;
 150         u32 fcclk, firc;
 151         int ret;
 152
 153         rc = devm_kzalloc(&pdev->dev, sizeof(*rc), GFP_KERNEL);
 154         if (!rc)
 155                 return -ENOMEM;
 156
 157         res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 158         rc->base = devm_ioremap_resource(&pdev->dev, res);
 159         if (IS_ERR(rc->base))
 160                 return PTR_ERR(rc->base);
 161
 162         rc->clk_reg = devm_clk_get(&pdev->dev, "reg");
 163         if (IS_ERR(rc->clk_reg)) {
 164                 dev_err(&pdev->dev, "reg clock not found\n");
 165                 return PTR_ERR(rc->clk_reg);
 166         }
 167
 168         rc->clk_delay = devm_clk_get(&pdev->dev, "delay");
 169         if (IS_ERR(rc->clk_delay)) {
 170                 dev_err(&pdev->dev, "delay clock not found\n");
 171                 return PTR_ERR(rc->clk_delay);
 172         }
 173
 174         ret = clk_prepare_enable(rc->clk_reg);
 175         if (ret) {
 176                 dev_err(&pdev->dev, "unable to enable reg clock\n");
 177                 return ret;
 178         }
 179
 180         ret = clk_prepare_enable(rc->clk_delay);
 181         if (ret) {
 182                 dev_err(&pdev->dev, "unable to enable delay clock\n");
 183                 goto dis_clk_reg;
 184         }
 185
 186         fcclk = clk_get_rate(rc->clk_reg) / USEC_PER_SEC;
 187         firc = clk_get_rate(rc->clk_delay) / USEC_PER_SEC;
 188         if (fcclk == 0 || firc == 0)
 189                 rc->delay_us = 2;
 190         else
 191                 rc->delay_us = DIV_ROUND_UP(fcclk, firc * firc);
 192
 193         spin_lock_init(&rc->lock);
 194
 195         rc->rcdev.owner = THIS_MODULE;
 196         rc->rcdev.nr_resets = 64;
 197         rc->rcdev.ops = &lpc18xx_rgu_ops;
 198         rc->rcdev.of_node = pdev->dev.of_node;
 199
 200         platform_set_drvdata(pdev, rc);
 201
 202         ret = reset_controller_register(&rc->rcdev);
 203         if (ret) {
 204                 dev_err(&pdev->dev, "unable to register device\n");
 205                 goto dis_clks;
 206         }
 207
 208         rgu_base = rc->base;
 209         ret = register_restart_handler(&lpc18xx_rgu_restart_nb);
 210         if (ret)
 211                 dev_warn(&pdev->dev, "failed to register restart handler\n");
 212
 213         return 0;
 214
 215 dis_clks:
 216         clk_disable_unprepare(rc->clk_delay);
 217 dis_clk_reg:
 218         clk_disable_unprepare(rc->clk_reg);
 219
 220         return ret;
 221 }
 222
 223 static int lpc18xx_rgu_remove(struct platform_device *pdev)
 224 {
 225         struct lpc18xx_rgu_data *rc = platform_get_drvdata(pdev);
 226         int ret;
 227
 228         ret = unregister_restart_handler(&lpc18xx_rgu_restart_nb);
 229         if (ret)
 230                 dev_warn(&pdev->dev, "failed to unregister restart handler\n");
 231
 232         reset_controller_unregister(&rc->rcdev);
 233
 234         clk_disable_unprepare(rc->clk_delay);
 235         clk_disable_unprepare(rc->clk_reg);
 236
 237         return 0;
 238 }
 239
 240 static const struct of_device_id lpc18xx_rgu_match[] = {
 241         { .compatible = "nxp,lpc1850-rgu" },
 242         { }
 243 };
 244 MODULE_DEVICE_TABLE(of, lpc18xx_rgu_match);
 245
 246 static struct platform_driver lpc18xx_rgu_driver = {
 247         .probe  = lpc18xx_rgu_probe,
 248         .remove = lpc18xx_rgu_remove,
 249         .driver = {
 250                 .name           = "lpc18xx-reset",
 251                 .of_match_table = lpc18xx_rgu_match,
 252         },
 253 };
 254 module_platform_driver(lpc18xx_rgu_driver);
 255
 256 MODULE_AUTHOR("Joachim Eastwood <manabian@gmail.com>");
 257 MODULE_DESCRIPTION("Reset driver for LPC18xx/43xx RGU");
 258 MODULE_LICENSE("GPL v2");