drivers/watchdog/meson_wdt.c

   1 /*
   2  *      Meson Watchdog Driver
   3  *
   4  *      Copyright (c) 2014 Carlo Caione
   5  *
   6  *      This program is free software; you can redistribute it and/or
   7  *      modify it under the terms of the GNU General Public License
   8  *      as published by the Free Software Foundation; either version
   9  *      2 of the License, or (at your option) any later version.
  10  */
  11
  12 #include <linux/clk.h>
  13 #include <linux/delay.h>
  14 #include <linux/err.h>
  15 #include <linux/init.h>
  16 #include <linux/io.h>
  17 #include <linux/kernel.h>
  18 #include <linux/module.h>
  19 #include <linux/moduleparam.h>
  20 #include <linux/of.h>
  21 #include <linux/of_device.h>
  22 #include <linux/platform_device.h>
  23 #include <linux/types.h>
  24 #include <linux/watchdog.h>
  25
  26 #define DRV_NAME                "meson_wdt"
  27
  28 #define MESON_WDT_TC            0x00
  29 #define MESON_WDT_DC_RESET      (3 << 24)
  30
  31 #define MESON_WDT_RESET         0x04
  32
  33 #define MESON_WDT_TIMEOUT       30
  34 #define MESON_WDT_MIN_TIMEOUT   1
  35
  36 #define MESON_SEC_TO_TC(s, c)   ((s) * (c))
  37
  38 static bool nowayout = WATCHDOG_NOWAYOUT;
  39 static unsigned int timeout = MESON_WDT_TIMEOUT;
  40
  41 struct meson_wdt_data {
  42         unsigned int enable;
  43         unsigned int terminal_count_mask;
  44         unsigned int count_unit;
  45 };
  46
  47 static struct meson_wdt_data meson6_wdt_data = {
  48         .enable                 = BIT(22),
  49         .terminal_count_mask    = 0x3fffff,
  50         .count_unit             = 100000, /* 10 us */
  51 };
  52
  53 static struct meson_wdt_data meson8b_wdt_data = {
  54         .enable                 = BIT(19),
  55         .terminal_count_mask    = 0xffff,
  56         .count_unit             = 7812, /* 128 us */
  57 };
  58
  59 struct meson_wdt_dev {
  60         struct watchdog_device wdt_dev;
  61         void __iomem *wdt_base;
  62         const struct meson_wdt_data *data;
  63 };
  64
  65 static int meson_wdt_restart(struct watchdog_device *wdt_dev,
  66                              unsigned long action, void *data)
  67 {
  68         struct meson_wdt_dev *meson_wdt = watchdog_get_drvdata(wdt_dev);
  69         u32 tc_reboot = MESON_WDT_DC_RESET;
  70
  71         tc_reboot |= meson_wdt->data->enable;
  72
  73         while (1) {
  74                 writel(tc_reboot, meson_wdt->wdt_base + MESON_WDT_TC);
  75                 mdelay(5);
  76         }
  77
  78         return 0;
  79 }
  80
  81 static int meson_wdt_ping(struct watchdog_device *wdt_dev)
  82 {
  83         struct meson_wdt_dev *meson_wdt = watchdog_get_drvdata(wdt_dev);
  84
  85         writel(0, meson_wdt->wdt_base + MESON_WDT_RESET);
  86
  87         return 0;
  88 }
  89
  90 static void meson_wdt_change_timeout(struct watchdog_device *wdt_dev,
  91                                      unsigned int timeout)
  92 {
  93         struct meson_wdt_dev *meson_wdt = watchdog_get_drvdata(wdt_dev);
  94         u32 reg;
  95
  96         reg = readl(meson_wdt->wdt_base + MESON_WDT_TC);
  97         reg &= ~meson_wdt->data->terminal_count_mask;
  98         reg |= MESON_SEC_TO_TC(timeout, meson_wdt->data->count_unit);
  99         writel(reg, meson_wdt->wdt_base + MESON_WDT_TC);
 100 }
 101
 102 static int meson_wdt_set_timeout(struct watchdog_device *wdt_dev,
 103                                  unsigned int timeout)
 104 {
 105         wdt_dev->timeout = timeout;
 106
 107         meson_wdt_change_timeout(wdt_dev, timeout);
 108         meson_wdt_ping(wdt_dev);
 109
 110         return 0;
 111 }
 112
 113 static int meson_wdt_stop(struct watchdog_device *wdt_dev)
 114 {
 115         struct meson_wdt_dev *meson_wdt = watchdog_get_drvdata(wdt_dev);
 116         u32 reg;
 117
 118         reg = readl(meson_wdt->wdt_base + MESON_WDT_TC);
 119         reg &= ~meson_wdt->data->enable;
 120         writel(reg, meson_wdt->wdt_base + MESON_WDT_TC);
 121
 122         return 0;
 123 }
 124
 125 static int meson_wdt_start(struct watchdog_device *wdt_dev)
 126 {
 127         struct meson_wdt_dev *meson_wdt = watchdog_get_drvdata(wdt_dev);
 128         u32 reg;
 129
 130         meson_wdt_change_timeout(wdt_dev, meson_wdt->wdt_dev.timeout);
 131         meson_wdt_ping(wdt_dev);
 132
 133         reg = readl(meson_wdt->wdt_base + MESON_WDT_TC);
 134         reg |= meson_wdt->data->enable;
 135         writel(reg, meson_wdt->wdt_base + MESON_WDT_TC);
 136
 137         return 0;
 138 }
 139
 140 static const struct watchdog_info meson_wdt_info = {
 141         .identity       = DRV_NAME,
 142         .options        = WDIOF_SETTIMEOUT |
 143                           WDIOF_KEEPALIVEPING |
 144                           WDIOF_MAGICCLOSE,
 145 };
 146
 147 static const struct watchdog_ops meson_wdt_ops = {
 148         .owner          = THIS_MODULE,
 149         .start          = meson_wdt_start,
 150         .stop           = meson_wdt_stop,
 151         .ping           = meson_wdt_ping,
 152         .set_timeout    = meson_wdt_set_timeout,
 153         .restart        = meson_wdt_restart,
 154 };
 155
 156 static const struct of_device_id meson_wdt_dt_ids[] = {
 157         { .compatible = "amlogic,meson6-wdt", .data = &meson6_wdt_data },
 158         { .compatible = "amlogic,meson8b-wdt", .data = &meson8b_wdt_data },
 159         { /* sentinel */ }
 160 };
 161 MODULE_DEVICE_TABLE(of, meson_wdt_dt_ids);
 162
 163 static int meson_wdt_probe(struct platform_device *pdev)
 164 {
 165         struct resource *res;
 166         struct meson_wdt_dev *meson_wdt;
 167         const struct of_device_id *of_id;
 168         int err;
 169
 170         meson_wdt = devm_kzalloc(&pdev->dev, sizeof(*meson_wdt), GFP_KERNEL);
 171         if (!meson_wdt)
 172                 return -ENOMEM;
 173
 174         res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 175         meson_wdt->wdt_base = devm_ioremap_resource(&pdev->dev, res);
 176         if (IS_ERR(meson_wdt->wdt_base))
 177                 return PTR_ERR(meson_wdt->wdt_base);
 178
 179         of_id = of_match_device(meson_wdt_dt_ids, &pdev->dev);
 180         if (!of_id) {
 181                 dev_err(&pdev->dev, "Unable to initialize WDT data\n");
 182                 return -ENODEV;
 183         }
 184         meson_wdt->data = of_id->data;
 185
 186         meson_wdt->wdt_dev.parent = &pdev->dev;
 187         meson_wdt->wdt_dev.info = &meson_wdt_info;
 188         meson_wdt->wdt_dev.ops = &meson_wdt_ops;
 189         meson_wdt->wdt_dev.max_timeout =
 190                 meson_wdt->data->terminal_count_mask / meson_wdt->data->count_unit;
 191         meson_wdt->wdt_dev.min_timeout = MESON_WDT_MIN_TIMEOUT;
 192         meson_wdt->wdt_dev.timeout = min_t(unsigned int,
 193                                            MESON_WDT_TIMEOUT,
 194                                            meson_wdt->wdt_dev.max_timeout);
 195
 196         watchdog_set_drvdata(&meson_wdt->wdt_dev, meson_wdt);
 197
 198         watchdog_init_timeout(&meson_wdt->wdt_dev, timeout, &pdev->dev);
 199         watchdog_set_nowayout(&meson_wdt->wdt_dev, nowayout);
 200         watchdog_set_restart_priority(&meson_wdt->wdt_dev, 128);
 201
 202         meson_wdt_stop(&meson_wdt->wdt_dev);
 203
 204         watchdog_stop_on_reboot(&meson_wdt->wdt_dev);
 205         err = devm_watchdog_register_device(&pdev->dev, &meson_wdt->wdt_dev);
 206         if (err)
 207                 return err;
 208
 209         dev_info(&pdev->dev, "Watchdog enabled (timeout=%d sec, nowayout=%d)",
 210                  meson_wdt->wdt_dev.timeout, nowayout);
 211
 212         return 0;
 213 }
 214
 215 static struct platform_driver meson_wdt_driver = {
 216         .probe          = meson_wdt_probe,
 217         .driver         = {
 218                 .name           = DRV_NAME,
 219                 .of_match_table = meson_wdt_dt_ids,
 220         },
 221 };
 222
 223 module_platform_driver(meson_wdt_driver);
 224
 225 module_param(timeout, uint, 0);
 226 MODULE_PARM_DESC(timeout, "Watchdog heartbeat in seconds");
 227
 228 module_param(nowayout, bool, 0);
 229 MODULE_PARM_DESC(nowayout,
 230                  "Watchdog cannot be stopped once started (default="
 231                  __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
 232
 233 MODULE_LICENSE("GPL");
 234 MODULE_AUTHOR("Carlo Caione <carlo@caione.org>");
 235 MODULE_DESCRIPTION("Meson Watchdog Timer Driver");