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 {
  67         struct meson_wdt_dev *meson_wdt = watchdog_get_drvdata(wdt_dev);
  68         u32 tc_reboot = MESON_WDT_DC_RESET;
  69
  70         tc_reboot |= meson_wdt->data->enable;
  71
  72         while (1) {
  73                 writel(tc_reboot, meson_wdt->wdt_base + MESON_WDT_TC);
  74                 mdelay(5);
  75         }
  76
  77         return 0;
  78 }
  79
  80 static int meson_wdt_ping(struct watchdog_device *wdt_dev)
  81 {
  82         struct meson_wdt_dev *meson_wdt = watchdog_get_drvdata(wdt_dev);
  83
  84         writel(0, meson_wdt->wdt_base + MESON_WDT_RESET);
  85
  86         return 0;
  87 }
  88
  89 static void meson_wdt_change_timeout(struct watchdog_device *wdt_dev,
  90                                      unsigned int timeout)
  91 {
  92         struct meson_wdt_dev *meson_wdt = watchdog_get_drvdata(wdt_dev);
  93         u32 reg;
  94
  95         reg = readl(meson_wdt->wdt_base + MESON_WDT_TC);
  96         reg &= ~meson_wdt->data->terminal_count_mask;
  97         reg |= MESON_SEC_TO_TC(timeout, meson_wdt->data->count_unit);
  98         writel(reg, meson_wdt->wdt_base + MESON_WDT_TC);
  99 }
 100
 101 static int meson_wdt_set_timeout(struct watchdog_device *wdt_dev,
 102                                  unsigned int timeout)
 103 {
 104         wdt_dev->timeout = timeout;
 105
 106         meson_wdt_change_timeout(wdt_dev, timeout);
 107         meson_wdt_ping(wdt_dev);
 108
 109         return 0;
 110 }
 111
 112 static int meson_wdt_stop(struct watchdog_device *wdt_dev)
 113 {
 114         struct meson_wdt_dev *meson_wdt = watchdog_get_drvdata(wdt_dev);
 115         u32 reg;
 116
 117         reg = readl(meson_wdt->wdt_base + MESON_WDT_TC);
 118         reg &= ~meson_wdt->data->enable;
 119         writel(reg, meson_wdt->wdt_base + MESON_WDT_TC);
 120
 121         return 0;
 122 }
 123
 124 static int meson_wdt_start(struct watchdog_device *wdt_dev)
 125 {
 126         struct meson_wdt_dev *meson_wdt = watchdog_get_drvdata(wdt_dev);
 127         u32 reg;
 128
 129         meson_wdt_change_timeout(wdt_dev, meson_wdt->wdt_dev.timeout);
 130         meson_wdt_ping(wdt_dev);
 131
 132         reg = readl(meson_wdt->wdt_base + MESON_WDT_TC);
 133         reg |= meson_wdt->data->enable;
 134         writel(reg, meson_wdt->wdt_base + MESON_WDT_TC);
 135
 136         return 0;
 137 }
 138
 139 static const struct watchdog_info meson_wdt_info = {
 140         .identity       = DRV_NAME,
 141         .options        = WDIOF_SETTIMEOUT |
 142                           WDIOF_KEEPALIVEPING |
 143                           WDIOF_MAGICCLOSE,
 144 };
 145
 146 static const struct watchdog_ops meson_wdt_ops = {
 147         .owner          = THIS_MODULE,
 148         .start          = meson_wdt_start,
 149         .stop           = meson_wdt_stop,
 150         .ping           = meson_wdt_ping,
 151         .set_timeout    = meson_wdt_set_timeout,
 152         .restart        = meson_wdt_restart,
 153 };
 154
 155 static const struct of_device_id meson_wdt_dt_ids[] = {
 156         { .compatible = "amlogic,meson6-wdt", .data = &meson6_wdt_data },
 157         { .compatible = "amlogic,meson8b-wdt", .data = &meson8b_wdt_data },
 158         { /* sentinel */ }
 159 };
 160 MODULE_DEVICE_TABLE(of, meson_wdt_dt_ids);
 161
 162 static int meson_wdt_probe(struct platform_device *pdev)
 163 {
 164         struct resource *res;
 165         struct meson_wdt_dev *meson_wdt;
 166         const struct of_device_id *of_id;
 167         int err;
 168
 169         meson_wdt = devm_kzalloc(&pdev->dev, sizeof(*meson_wdt), GFP_KERNEL);
 170         if (!meson_wdt)
 171                 return -ENOMEM;
 172
 173         res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 174         meson_wdt->wdt_base = devm_ioremap_resource(&pdev->dev, res);
 175         if (IS_ERR(meson_wdt->wdt_base))
 176                 return PTR_ERR(meson_wdt->wdt_base);
 177
 178         of_id = of_match_device(meson_wdt_dt_ids, &pdev->dev);
 179         if (!of_id) {
 180                 dev_err(&pdev->dev, "Unable to initialize WDT data\n");
 181                 return -ENODEV;
 182         }
 183         meson_wdt->data = of_id->data;
 184
 185         meson_wdt->wdt_dev.parent = &pdev->dev;
 186         meson_wdt->wdt_dev.info = &meson_wdt_info;
 187         meson_wdt->wdt_dev.ops = &meson_wdt_ops;
 188         meson_wdt->wdt_dev.max_timeout =
 189                 meson_wdt->data->terminal_count_mask / meson_wdt->data->count_unit;
 190         meson_wdt->wdt_dev.min_timeout = MESON_WDT_MIN_TIMEOUT;
 191         meson_wdt->wdt_dev.timeout = min_t(unsigned int,
 192                                            MESON_WDT_TIMEOUT,
 193                                            meson_wdt->wdt_dev.max_timeout);
 194
 195         watchdog_set_drvdata(&meson_wdt->wdt_dev, meson_wdt);
 196
 197         watchdog_init_timeout(&meson_wdt->wdt_dev, timeout, &pdev->dev);
 198         watchdog_set_nowayout(&meson_wdt->wdt_dev, nowayout);
 199         watchdog_set_restart_priority(&meson_wdt->wdt_dev, 128);
 200
 201         meson_wdt_stop(&meson_wdt->wdt_dev);
 202
 203         err = watchdog_register_device(&meson_wdt->wdt_dev);
 204         if (err)
 205                 return err;
 206
 207         platform_set_drvdata(pdev, meson_wdt);
 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 int meson_wdt_remove(struct platform_device *pdev)
 216 {
 217         struct meson_wdt_dev *meson_wdt = platform_get_drvdata(pdev);
 218
 219         watchdog_unregister_device(&meson_wdt->wdt_dev);
 220
 221         return 0;
 222 }
 223
 224 static void meson_wdt_shutdown(struct platform_device *pdev)
 225 {
 226         struct meson_wdt_dev *meson_wdt = platform_get_drvdata(pdev);
 227
 228         meson_wdt_stop(&meson_wdt->wdt_dev);
 229 }
 230
 231 static struct platform_driver meson_wdt_driver = {
 232         .probe          = meson_wdt_probe,
 233         .remove         = meson_wdt_remove,
 234         .shutdown       = meson_wdt_shutdown,
 235         .driver         = {
 236                 .name           = DRV_NAME,
 237                 .of_match_table = meson_wdt_dt_ids,
 238         },
 239 };
 240
 241 module_platform_driver(meson_wdt_driver);
 242
 243 module_param(timeout, uint, 0);
 244 MODULE_PARM_DESC(timeout, "Watchdog heartbeat in seconds");
 245
 246 module_param(nowayout, bool, 0);
 247 MODULE_PARM_DESC(nowayout,
 248                  "Watchdog cannot be stopped once started (default="
 249                  __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
 250
 251 MODULE_LICENSE("GPL");
 252 MODULE_AUTHOR("Carlo Caione <carlo@caione.org>");
 253 MODULE_DESCRIPTION("Meson Watchdog Timer Driver");