drivers/watchdog/da9063_wdt.c

   1 // SPDX-License-Identifier: GPL-2.0+
   2 /*
   3  * Watchdog driver for DA9063 PMICs.
   4  *
   5  * Copyright(c) 2012 Dialog Semiconductor Ltd.
   6  *
   7  * Author: Mariusz Wojtasik <mariusz.wojtasik@diasemi.com>
   8  *
   9  */
  10
  11 #include <linux/kernel.h>
  12 #include <linux/module.h>
  13 #include <linux/watchdog.h>
  14 #include <linux/platform_device.h>
  15 #include <linux/uaccess.h>
  16 #include <linux/slab.h>
  17 #include <linux/delay.h>
  18 #include <linux/mfd/da9063/registers.h>
  19 #include <linux/mfd/da9063/core.h>
  20 #include <linux/regmap.h>
  21
  22 /*
  23  * Watchdog selector to timeout in seconds.
  24  *   0: WDT disabled;
  25  *   others: timeout = 2048 ms * 2^(TWDSCALE-1).
  26  */
  27 static const unsigned int wdt_timeout[] = { 0, 2, 4, 8, 16, 32, 65, 131 };
  28 #define DA9063_TWDSCALE_DISABLE         0
  29 #define DA9063_TWDSCALE_MIN             1
  30 #define DA9063_TWDSCALE_MAX             (ARRAY_SIZE(wdt_timeout) - 1)
  31 #define DA9063_WDT_MIN_TIMEOUT          wdt_timeout[DA9063_TWDSCALE_MIN]
  32 #define DA9063_WDT_MAX_TIMEOUT          wdt_timeout[DA9063_TWDSCALE_MAX]
  33 #define DA9063_WDG_TIMEOUT              wdt_timeout[3]
  34 #define DA9063_RESET_PROTECTION_MS      256
  35
  36 static unsigned int da9063_wdt_timeout_to_sel(unsigned int secs)
  37 {
  38         unsigned int i;
  39
  40         for (i = DA9063_TWDSCALE_MIN; i <= DA9063_TWDSCALE_MAX; i++) {
  41                 if (wdt_timeout[i] >= secs)
  42                         return i;
  43         }
  44
  45         return DA9063_TWDSCALE_MAX;
  46 }
  47
  48 /*
  49  * Read the currently active timeout.
  50  * Zero means the watchdog is disabled.
  51  */
  52 static unsigned int da9063_wdt_read_timeout(struct da9063 *da9063)
  53 {
  54         unsigned int val;
  55
  56         regmap_read(da9063->regmap, DA9063_REG_CONTROL_D, &val);
  57
  58         return wdt_timeout[val & DA9063_TWDSCALE_MASK];
  59 }
  60
  61 static int da9063_wdt_disable_timer(struct da9063 *da9063)
  62 {
  63         return regmap_update_bits(da9063->regmap, DA9063_REG_CONTROL_D,
  64                                   DA9063_TWDSCALE_MASK,
  65                                   DA9063_TWDSCALE_DISABLE);
  66 }
  67
  68 static int
  69 da9063_wdt_update_timeout(struct da9063 *da9063, unsigned int timeout)
  70 {
  71         unsigned int regval;
  72         int ret;
  73
  74         /*
  75          * The watchdog triggers a reboot if a timeout value is already
  76          * programmed because the timeout value combines two functions
  77          * in one: indicating the counter limit and starting the watchdog.
  78          * The watchdog must be disabled to be able to change the timeout
  79          * value if the watchdog is already running. Then we can set the
  80          * new timeout value which enables the watchdog again.
  81          */
  82         ret = da9063_wdt_disable_timer(da9063);
  83         if (ret)
  84                 return ret;
  85
  86         usleep_range(150, 300);
  87         regval = da9063_wdt_timeout_to_sel(timeout);
  88
  89         return regmap_update_bits(da9063->regmap, DA9063_REG_CONTROL_D,
  90                                   DA9063_TWDSCALE_MASK, regval);
  91 }
  92
  93 static int da9063_wdt_start(struct watchdog_device *wdd)
  94 {
  95         struct da9063 *da9063 = watchdog_get_drvdata(wdd);
  96         int ret;
  97
  98         ret = da9063_wdt_update_timeout(da9063, wdd->timeout);
  99         if (ret)
 100                 dev_err(da9063->dev, "Watchdog failed to start (err = %d)\n",
 101                         ret);
 102
 103         return ret;
 104 }
 105
 106 static int da9063_wdt_stop(struct watchdog_device *wdd)
 107 {
 108         struct da9063 *da9063 = watchdog_get_drvdata(wdd);
 109         int ret;
 110
 111         ret = da9063_wdt_disable_timer(da9063);
 112         if (ret)
 113                 dev_alert(da9063->dev, "Watchdog failed to stop (err = %d)\n",
 114                           ret);
 115
 116         return ret;
 117 }
 118
 119 static int da9063_wdt_ping(struct watchdog_device *wdd)
 120 {
 121         struct da9063 *da9063 = watchdog_get_drvdata(wdd);
 122         int ret;
 123
 124         /*
 125          * Prevent pings from occurring late in system poweroff/reboot sequence
 126          * and possibly locking out restart handler from accessing i2c bus.
 127          */
 128         if (system_state > SYSTEM_RUNNING)
 129                 return 0;
 130
 131         ret = regmap_write(da9063->regmap, DA9063_REG_CONTROL_F,
 132                            DA9063_WATCHDOG);
 133         if (ret)
 134                 dev_alert(da9063->dev, "Failed to ping the watchdog (err = %d)\n",
 135                           ret);
 136
 137         return ret;
 138 }
 139
 140 static int da9063_wdt_set_timeout(struct watchdog_device *wdd,
 141                                   unsigned int timeout)
 142 {
 143         struct da9063 *da9063 = watchdog_get_drvdata(wdd);
 144         int ret = 0;
 145
 146         /*
 147          * There are two cases when a set_timeout() will be called:
 148          * 1. The watchdog is off and someone wants to set the timeout for the
 149          *    further use.
 150          * 2. The watchdog is already running and a new timeout value should be
 151          *    set.
 152          *
 153          * The watchdog can't store a timeout value not equal zero without
 154          * enabling the watchdog, so the timeout must be buffered by the driver.
 155          */
 156         if (watchdog_active(wdd))
 157                 ret = da9063_wdt_update_timeout(da9063, timeout);
 158
 159         if (ret)
 160                 dev_err(da9063->dev, "Failed to set watchdog timeout (err = %d)\n",
 161                         ret);
 162         else
 163                 wdd->timeout = wdt_timeout[da9063_wdt_timeout_to_sel(timeout)];
 164
 165         return ret;
 166 }
 167
 168 static int da9063_wdt_restart(struct watchdog_device *wdd, unsigned long action,
 169                               void *data)
 170 {
 171         struct da9063 *da9063 = watchdog_get_drvdata(wdd);
 172         int ret;
 173
 174         ret = regmap_write(da9063->regmap, DA9063_REG_CONTROL_F,
 175                            DA9063_SHUTDOWN);
 176         if (ret)
 177                 dev_alert(da9063->dev, "Failed to shutdown (err = %d)\n",
 178                           ret);
 179
 180         return ret;
 181 }
 182
 183 static const struct watchdog_info da9063_watchdog_info = {
 184         .options = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING,
 185         .identity = "DA9063 Watchdog",
 186 };
 187
 188 static const struct watchdog_ops da9063_watchdog_ops = {
 189         .owner = THIS_MODULE,
 190         .start = da9063_wdt_start,
 191         .stop = da9063_wdt_stop,
 192         .ping = da9063_wdt_ping,
 193         .set_timeout = da9063_wdt_set_timeout,
 194         .restart = da9063_wdt_restart,
 195 };
 196
 197 static int da9063_wdt_probe(struct platform_device *pdev)
 198 {
 199         struct device *dev = &pdev->dev;
 200         struct da9063 *da9063;
 201         struct watchdog_device *wdd;
 202         unsigned int timeout;
 203
 204         if (!dev->parent)
 205                 return -EINVAL;
 206
 207         da9063 = dev_get_drvdata(dev->parent);
 208         if (!da9063)
 209                 return -EINVAL;
 210
 211         wdd = devm_kzalloc(dev, sizeof(*wdd), GFP_KERNEL);
 212         if (!wdd)
 213                 return -ENOMEM;
 214
 215         wdd->info = &da9063_watchdog_info;
 216         wdd->ops = &da9063_watchdog_ops;
 217         wdd->min_timeout = DA9063_WDT_MIN_TIMEOUT;
 218         wdd->max_timeout = DA9063_WDT_MAX_TIMEOUT;
 219         wdd->min_hw_heartbeat_ms = DA9063_RESET_PROTECTION_MS;
 220         wdd->parent = dev;
 221         wdd->status = WATCHDOG_NOWAYOUT_INIT_STATUS;
 222
 223         watchdog_set_restart_priority(wdd, 128);
 224         watchdog_set_drvdata(wdd, da9063);
 225
 226         wdd->timeout = DA9063_WDG_TIMEOUT;
 227
 228         /* Use pre-configured timeout if watchdog is already running. */
 229         timeout = da9063_wdt_read_timeout(da9063);
 230         if (timeout)
 231                 wdd->timeout = timeout;
 232
 233         /* Set timeout, maybe override it with DT value, scale it */
 234         watchdog_init_timeout(wdd, 0, dev);
 235         da9063_wdt_set_timeout(wdd, wdd->timeout);
 236
 237         /* Update timeout if the watchdog is already running. */
 238         if (timeout) {
 239                 da9063_wdt_update_timeout(da9063, wdd->timeout);
 240                 set_bit(WDOG_HW_RUNNING, &wdd->status);
 241         }
 242
 243         return devm_watchdog_register_device(dev, wdd);
 244 }
 245
 246 static struct platform_driver da9063_wdt_driver = {
 247         .probe = da9063_wdt_probe,
 248         .driver = {
 249                 .name = DA9063_DRVNAME_WATCHDOG,
 250         },
 251 };
 252 module_platform_driver(da9063_wdt_driver);
 253
 254 MODULE_AUTHOR("Mariusz Wojtasik <mariusz.wojtasik@diasemi.com>");
 255 MODULE_DESCRIPTION("Watchdog driver for Dialog DA9063");
 256 MODULE_LICENSE("GPL");
 257 MODULE_ALIAS("platform:" DA9063_DRVNAME_WATCHDOG);