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/init.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 notifier_block restart_nb;
  39         struct clk *clk_delay;
  40         struct clk *clk_reg;
  41         void __iomem *base;
  42         spinlock_t lock;
  43         u32 delay_us;
  44 };
  45
  46 #define to_rgu_data(p) container_of(p, struct lpc18xx_rgu_data, rcdev)
  47
  48 static int lpc18xx_rgu_restart(struct notifier_block *nb, unsigned long mode,
  49                                void *cmd)
  50 {
  51         struct lpc18xx_rgu_data *rc = container_of(nb, struct lpc18xx_rgu_data,
  52                                                    restart_nb);
  53
  54         writel(BIT(LPC18XX_RGU_CORE_RST), rc->base + LPC18XX_RGU_CTRL0);
  55         mdelay(2000);
  56
  57         pr_emerg("%s: unable to restart system\n", __func__);
  58
  59         return NOTIFY_DONE;
  60 }
  61
  62 /*
  63  * The LPC18xx RGU has mostly self-deasserting resets except for the
  64  * two reset lines going to the internal Cortex-M0 cores.
  65  *
  66  * To prevent the M0 core resets from accidentally getting deasserted
  67  * status register must be check and bits in control register set to
  68  * preserve the state.
  69  */
  70 static int lpc18xx_rgu_setclear_reset(struct reset_controller_dev *rcdev,
  71                                       unsigned long id, bool set)
  72 {
  73         struct lpc18xx_rgu_data *rc = to_rgu_data(rcdev);
  74         u32 stat_offset = LPC18XX_RGU_ACTIVE_STATUS0;
  75         u32 ctrl_offset = LPC18XX_RGU_CTRL0;
  76         unsigned long flags;
  77         u32 stat, rst_bit;
  78
  79         stat_offset += (id / LPC18XX_RGU_RESETS_PER_REG) * sizeof(u32);
  80         ctrl_offset += (id / LPC18XX_RGU_RESETS_PER_REG) * sizeof(u32);
  81         rst_bit = 1 << (id % LPC18XX_RGU_RESETS_PER_REG);
  82
  83         spin_lock_irqsave(&rc->lock, flags);
  84         stat = ~readl(rc->base + stat_offset);
  85         if (set)
  86                 writel(stat | rst_bit, rc->base + ctrl_offset);
  87         else
  88                 writel(stat & ~rst_bit, rc->base + ctrl_offset);
  89         spin_unlock_irqrestore(&rc->lock, flags);
  90
  91         return 0;
  92 }
  93
  94 static int lpc18xx_rgu_assert(struct reset_controller_dev *rcdev,
  95                               unsigned long id)
  96 {
  97         return lpc18xx_rgu_setclear_reset(rcdev, id, true);
  98 }
  99
 100 static int lpc18xx_rgu_deassert(struct reset_controller_dev *rcdev,
 101                                 unsigned long id)
 102 {
 103         return lpc18xx_rgu_setclear_reset(rcdev, id, false);
 104 }
 105
 106 /* Only M0 cores require explicit reset deassert */
 107 static int lpc18xx_rgu_reset(struct reset_controller_dev *rcdev,
 108                              unsigned long id)
 109 {
 110         struct lpc18xx_rgu_data *rc = to_rgu_data(rcdev);
 111
 112         lpc18xx_rgu_assert(rcdev, id);
 113         udelay(rc->delay_us);
 114
 115         switch (id) {
 116         case LPC43XX_RGU_M0SUB_RST:
 117         case LPC43XX_RGU_M0APP_RST:
 118                 lpc18xx_rgu_setclear_reset(rcdev, id, false);
 119         }
 120
 121         return 0;
 122 }
 123
 124 static int lpc18xx_rgu_status(struct reset_controller_dev *rcdev,
 125                               unsigned long id)
 126 {
 127         struct lpc18xx_rgu_data *rc = to_rgu_data(rcdev);
 128         u32 bit, offset = LPC18XX_RGU_ACTIVE_STATUS0;
 129
 130         offset += (id / LPC18XX_RGU_RESETS_PER_REG) * sizeof(u32);
 131         bit = 1 << (id % LPC18XX_RGU_RESETS_PER_REG);
 132
 133         return !(readl(rc->base + offset) & bit);
 134 }
 135
 136 static const struct reset_control_ops lpc18xx_rgu_ops = {
 137         .reset          = lpc18xx_rgu_reset,
 138         .assert         = lpc18xx_rgu_assert,
 139         .deassert       = lpc18xx_rgu_deassert,
 140         .status         = lpc18xx_rgu_status,
 141 };
 142
 143 static int lpc18xx_rgu_probe(struct platform_device *pdev)
 144 {
 145         struct lpc18xx_rgu_data *rc;
 146         struct resource *res;
 147         u32 fcclk, firc;
 148         int ret;
 149
 150         rc = devm_kzalloc(&pdev->dev, sizeof(*rc), GFP_KERNEL);
 151         if (!rc)
 152                 return -ENOMEM;
 153
 154         res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 155         rc->base = devm_ioremap_resource(&pdev->dev, res);
 156         if (IS_ERR(rc->base))
 157                 return PTR_ERR(rc->base);
 158
 159         rc->clk_reg = devm_clk_get(&pdev->dev, "reg");
 160         if (IS_ERR(rc->clk_reg)) {
 161                 dev_err(&pdev->dev, "reg clock not found\n");
 162                 return PTR_ERR(rc->clk_reg);
 163         }
 164
 165         rc->clk_delay = devm_clk_get(&pdev->dev, "delay");
 166         if (IS_ERR(rc->clk_delay)) {
 167                 dev_err(&pdev->dev, "delay clock not found\n");
 168                 return PTR_ERR(rc->clk_delay);
 169         }
 170
 171         ret = clk_prepare_enable(rc->clk_reg);
 172         if (ret) {
 173                 dev_err(&pdev->dev, "unable to enable reg clock\n");
 174                 return ret;
 175         }
 176
 177         ret = clk_prepare_enable(rc->clk_delay);
 178         if (ret) {
 179                 dev_err(&pdev->dev, "unable to enable delay clock\n");
 180                 goto dis_clk_reg;
 181         }
 182
 183         fcclk = clk_get_rate(rc->clk_reg) / USEC_PER_SEC;
 184         firc = clk_get_rate(rc->clk_delay) / USEC_PER_SEC;
 185         if (fcclk == 0 || firc == 0)
 186                 rc->delay_us = 2;
 187         else
 188                 rc->delay_us = DIV_ROUND_UP(fcclk, firc * firc);
 189
 190         spin_lock_init(&rc->lock);
 191
 192         rc->rcdev.owner = THIS_MODULE;
 193         rc->rcdev.nr_resets = 64;
 194         rc->rcdev.ops = &lpc18xx_rgu_ops;
 195         rc->rcdev.of_node = pdev->dev.of_node;
 196
 197         platform_set_drvdata(pdev, rc);
 198
 199         ret = reset_controller_register(&rc->rcdev);
 200         if (ret) {
 201                 dev_err(&pdev->dev, "unable to register device\n");
 202                 goto dis_clks;
 203         }
 204
 205         rc->restart_nb.priority = 192,
 206         rc->restart_nb.notifier_call = lpc18xx_rgu_restart,
 207         ret = register_restart_handler(&rc->restart_nb);
 208         if (ret)
 209                 dev_warn(&pdev->dev, "failed to register restart handler\n");
 210
 211         return 0;
 212
 213 dis_clks:
 214         clk_disable_unprepare(rc->clk_delay);
 215 dis_clk_reg:
 216         clk_disable_unprepare(rc->clk_reg);
 217
 218         return ret;
 219 }
 220
 221 static const struct of_device_id lpc18xx_rgu_match[] = {
 222         { .compatible = "nxp,lpc1850-rgu" },
 223         { }
 224 };
 225
 226 static struct platform_driver lpc18xx_rgu_driver = {
 227         .probe  = lpc18xx_rgu_probe,
 228         .driver = {
 229                 .name                   = "lpc18xx-reset",
 230                 .of_match_table         = lpc18xx_rgu_match,
 231                 .suppress_bind_attrs    = true,
 232         },
 233 };
 234 builtin_platform_driver(lpc18xx_rgu_driver);