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/i2c.h>
  18 #include <linux/delay.h>
  19 #include <linux/mfd/da9063/registers.h>
  20 #include <linux/mfd/da9063/core.h>
  21 #include <linux/regmap.h>
  22
  23 /*
  24  * Watchdog selector to timeout in seconds.
  25  *   0: WDT disabled;
  26  *   others: timeout = 2048 ms * 2^(TWDSCALE-1).
  27  */
  28 static const unsigned int wdt_timeout[] = { 0, 2, 4, 8, 16, 32, 65, 131 };
  29 #define DA9063_TWDSCALE_DISABLE         0
  30 #define DA9063_TWDSCALE_MIN             1
  31 #define DA9063_TWDSCALE_MAX             (ARRAY_SIZE(wdt_timeout) - 1)
  32 #define DA9063_WDT_MIN_TIMEOUT          wdt_timeout[DA9063_TWDSCALE_MIN]
  33 #define DA9063_WDT_MAX_TIMEOUT          wdt_timeout[DA9063_TWDSCALE_MAX]
  34 #define DA9063_WDG_TIMEOUT              wdt_timeout[3]
  35 #define DA9063_RESET_PROTECTION_MS      256
  36
  37 static unsigned int da9063_wdt_timeout_to_sel(unsigned int secs)
  38 {
  39         unsigned int i;
  40
  41         for (i = DA9063_TWDSCALE_MIN; i <= DA9063_TWDSCALE_MAX; i++) {
  42                 if (wdt_timeout[i] >= secs)
  43                         return i;
  44         }
  45
  46         return DA9063_TWDSCALE_MAX;
  47 }
  48
  49 /*
  50  * Read the currently active timeout.
  51  * Zero means the watchdog is disabled.
  52  */
  53 static unsigned int da9063_wdt_read_timeout(struct da9063 *da9063)
  54 {
  55         unsigned int val;
  56
  57         regmap_read(da9063->regmap, DA9063_REG_CONTROL_D, &val);
  58
  59         return wdt_timeout[val & DA9063_TWDSCALE_MASK];
  60 }
  61
  62 static int da9063_wdt_disable_timer(struct da9063 *da9063)
  63 {
  64         return regmap_update_bits(da9063->regmap, DA9063_REG_CONTROL_D,
  65                                   DA9063_TWDSCALE_MASK,
  66                                   DA9063_TWDSCALE_DISABLE);
  67 }
  68
  69 static int
  70 da9063_wdt_update_timeout(struct da9063 *da9063, unsigned int timeout)
  71 {
  72         unsigned int regval;
  73         int ret;
  74
  75         /*
  76          * The watchdog triggers a reboot if a timeout value is already
  77          * programmed because the timeout value combines two functions
  78          * in one: indicating the counter limit and starting the watchdog.
  79          * The watchdog must be disabled to be able to change the timeout
  80          * value if the watchdog is already running. Then we can set the
  81          * new timeout value which enables the watchdog again.
  82          */
  83         ret = da9063_wdt_disable_timer(da9063);
  84         if (ret)
  85                 return ret;
  86
  87         usleep_range(150, 300);
  88         regval = da9063_wdt_timeout_to_sel(timeout);
  89
  90         return regmap_update_bits(da9063->regmap, DA9063_REG_CONTROL_D,
  91                                   DA9063_TWDSCALE_MASK, regval);
  92 }
  93
  94 static int da9063_wdt_start(struct watchdog_device *wdd)
  95 {
  96         struct da9063 *da9063 = watchdog_get_drvdata(wdd);
  97         int ret;
  98
  99         ret = da9063_wdt_update_timeout(da9063, wdd->timeout);
 100         if (ret)
 101                 dev_err(da9063->dev, "Watchdog failed to start (err = %d)\n",
 102                         ret);
 103
 104         return ret;
 105 }
 106
 107 static int da9063_wdt_stop(struct watchdog_device *wdd)
 108 {
 109         struct da9063 *da9063 = watchdog_get_drvdata(wdd);
 110         int ret;
 111
 112         ret = da9063_wdt_disable_timer(da9063);
 113         if (ret)
 114                 dev_alert(da9063->dev, "Watchdog failed to stop (err = %d)\n",
 115                           ret);
 116
 117         return ret;
 118 }
 119
 120 static int da9063_wdt_ping(struct watchdog_device *wdd)
 121 {
 122         struct da9063 *da9063 = watchdog_get_drvdata(wdd);
 123         int ret;
 124
 125         /*
 126          * Prevent pings from occurring late in system poweroff/reboot sequence
 127          * and possibly locking out restart handler from accessing i2c bus.
 128          */
 129         if (system_state > SYSTEM_RUNNING)
 130                 return 0;
 131
 132         ret = regmap_write(da9063->regmap, DA9063_REG_CONTROL_F,
 133                            DA9063_WATCHDOG);
 134         if (ret)
 135                 dev_alert(da9063->dev, "Failed to ping the watchdog (err = %d)\n",
 136                           ret);
 137
 138         return ret;
 139 }
 140
 141 static int da9063_wdt_set_timeout(struct watchdog_device *wdd,
 142                                   unsigned int timeout)
 143 {
 144         struct da9063 *da9063 = watchdog_get_drvdata(wdd);
 145         int ret = 0;
 146
 147         /*
 148          * There are two cases when a set_timeout() will be called:
 149          * 1. The watchdog is off and someone wants to set the timeout for the
 150          *    further use.
 151          * 2. The watchdog is already running and a new timeout value should be
 152          *    set.
 153          *
 154          * The watchdog can't store a timeout value not equal zero without
 155          * enabling the watchdog, so the timeout must be buffered by the driver.
 156          */
 157         if (watchdog_active(wdd))
 158                 ret = da9063_wdt_update_timeout(da9063, timeout);
 159
 160         if (ret)
 161                 dev_err(da9063->dev, "Failed to set watchdog timeout (err = %d)\n",
 162                         ret);
 163         else
 164                 wdd->timeout = wdt_timeout[da9063_wdt_timeout_to_sel(timeout)];
 165
 166         return ret;
 167 }
 168
 169 static int da9063_wdt_restart(struct watchdog_device *wdd, unsigned long action,
 170                               void *data)
 171 {
 172         struct da9063 *da9063 = watchdog_get_drvdata(wdd);
 173         struct i2c_client *client = to_i2c_client(da9063->dev);
 174         int ret;
 175
 176         /* Don't use regmap because it is not atomic safe */
 177         ret = i2c_smbus_write_byte_data(client, DA9063_REG_CONTROL_F,
 178                                         DA9063_SHUTDOWN);
 179         if (ret < 0)
 180                 dev_alert(da9063->dev, "Failed to shutdown (err = %d)\n",
 181                           ret);
 182
 183         /* wait for reset to assert... */
 184         mdelay(500);
 185
 186         return ret;
 187 }
 188
 189 static const struct watchdog_info da9063_watchdog_info = {
 190         .options = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING,
 191         .identity = "DA9063 Watchdog",
 192 };
 193
 194 static const struct watchdog_ops da9063_watchdog_ops = {
 195         .owner = THIS_MODULE,
 196         .start = da9063_wdt_start,
 197         .stop = da9063_wdt_stop,
 198         .ping = da9063_wdt_ping,
 199         .set_timeout = da9063_wdt_set_timeout,
 200         .restart = da9063_wdt_restart,
 201 };
 202
 203 static int da9063_wdt_probe(struct platform_device *pdev)
 204 {
 205         struct device *dev = &pdev->dev;
 206         struct da9063 *da9063;
 207         struct watchdog_device *wdd;
 208         unsigned int timeout;
 209
 210         if (!dev->parent)
 211                 return -EINVAL;
 212
 213         da9063 = dev_get_drvdata(dev->parent);
 214         if (!da9063)
 215                 return -EINVAL;
 216
 217         wdd = devm_kzalloc(dev, sizeof(*wdd), GFP_KERNEL);
 218         if (!wdd)
 219                 return -ENOMEM;
 220
 221         wdd->info = &da9063_watchdog_info;
 222         wdd->ops = &da9063_watchdog_ops;
 223         wdd->min_timeout = DA9063_WDT_MIN_TIMEOUT;
 224         wdd->max_timeout = DA9063_WDT_MAX_TIMEOUT;
 225         wdd->min_hw_heartbeat_ms = DA9063_RESET_PROTECTION_MS;
 226         wdd->parent = dev;
 227         wdd->status = WATCHDOG_NOWAYOUT_INIT_STATUS;
 228
 229         watchdog_set_restart_priority(wdd, 128);
 230         watchdog_set_drvdata(wdd, da9063);
 231
 232         wdd->timeout = DA9063_WDG_TIMEOUT;
 233
 234         /* Use pre-configured timeout if watchdog is already running. */
 235         timeout = da9063_wdt_read_timeout(da9063);
 236         if (timeout)
 237                 wdd->timeout = timeout;
 238
 239         /* Set timeout, maybe override it with DT value, scale it */
 240         watchdog_init_timeout(wdd, 0, dev);
 241         da9063_wdt_set_timeout(wdd, wdd->timeout);
 242
 243         /* Update timeout if the watchdog is already running. */
 244         if (timeout) {
 245                 da9063_wdt_update_timeout(da9063, wdd->timeout);
 246                 set_bit(WDOG_HW_RUNNING, &wdd->status);
 247         }
 248
 249         return devm_watchdog_register_device(dev, wdd);
 250 }
 251
 252 static struct platform_driver da9063_wdt_driver = {
 253         .probe = da9063_wdt_probe,
 254         .driver = {
 255                 .name = DA9063_DRVNAME_WATCHDOG,
 256         },
 257 };
 258 module_platform_driver(da9063_wdt_driver);
 259
 260 MODULE_AUTHOR("Mariusz Wojtasik <mariusz.wojtasik@diasemi.com>");
 261 MODULE_DESCRIPTION("Watchdog driver for Dialog DA9063");
 262 MODULE_LICENSE("GPL");
 263 MODULE_ALIAS("platform:" DA9063_DRVNAME_WATCHDOG);