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/property.h>
  22 #include <linux/regmap.h>
  23
  24 /*
  25  * Watchdog selector to timeout in seconds.
  26  *   0: WDT disabled;
  27  *   others: timeout = 2048 ms * 2^(TWDSCALE-1).
  28  */
  29 static const unsigned int wdt_timeout[] = { 0, 2, 4, 8, 16, 32, 65, 131 };
  30 static bool use_sw_pm;
  31
  32 #define DA9063_TWDSCALE_DISABLE         0
  33 #define DA9063_TWDSCALE_MIN             1
  34 #define DA9063_TWDSCALE_MAX             (ARRAY_SIZE(wdt_timeout) - 1)
  35 #define DA9063_WDT_MIN_TIMEOUT          wdt_timeout[DA9063_TWDSCALE_MIN]
  36 #define DA9063_WDT_MAX_TIMEOUT          wdt_timeout[DA9063_TWDSCALE_MAX]
  37 #define DA9063_WDG_TIMEOUT              wdt_timeout[3]
  38 #define DA9063_RESET_PROTECTION_MS      256
  39
  40 static unsigned int da9063_wdt_timeout_to_sel(unsigned int secs)
  41 {
  42         unsigned int i;
  43
  44         for (i = DA9063_TWDSCALE_MIN; i <= DA9063_TWDSCALE_MAX; i++) {
  45                 if (wdt_timeout[i] >= secs)
  46                         return i;
  47         }
  48
  49         return DA9063_TWDSCALE_MAX;
  50 }
  51
  52 /*
  53  * Read the currently active timeout.
  54  * Zero means the watchdog is disabled.
  55  */
  56 static unsigned int da9063_wdt_read_timeout(struct da9063 *da9063)
  57 {
  58         unsigned int val;
  59
  60         regmap_read(da9063->regmap, DA9063_REG_CONTROL_D, &val);
  61
  62         return wdt_timeout[val & DA9063_TWDSCALE_MASK];
  63 }
  64
  65 static int da9063_wdt_disable_timer(struct da9063 *da9063)
  66 {
  67         return regmap_update_bits(da9063->regmap, DA9063_REG_CONTROL_D,
  68                                   DA9063_TWDSCALE_MASK,
  69                                   DA9063_TWDSCALE_DISABLE);
  70 }
  71
  72 static int
  73 da9063_wdt_update_timeout(struct da9063 *da9063, unsigned int timeout)
  74 {
  75         unsigned int regval;
  76         int ret;
  77
  78         /*
  79          * The watchdog triggers a reboot if a timeout value is already
  80          * programmed because the timeout value combines two functions
  81          * in one: indicating the counter limit and starting the watchdog.
  82          * The watchdog must be disabled to be able to change the timeout
  83          * value if the watchdog is already running. Then we can set the
  84          * new timeout value which enables the watchdog again.
  85          */
  86         ret = da9063_wdt_disable_timer(da9063);
  87         if (ret)
  88                 return ret;
  89
  90         usleep_range(150, 300);
  91         regval = da9063_wdt_timeout_to_sel(timeout);
  92
  93         return regmap_update_bits(da9063->regmap, DA9063_REG_CONTROL_D,
  94                                   DA9063_TWDSCALE_MASK, regval);
  95 }
  96
  97 static int da9063_wdt_start(struct watchdog_device *wdd)
  98 {
  99         struct da9063 *da9063 = watchdog_get_drvdata(wdd);
 100         int ret;
 101
 102         ret = da9063_wdt_update_timeout(da9063, wdd->timeout);
 103         if (ret)
 104                 dev_err(da9063->dev, "Watchdog failed to start (err = %d)\n",
 105                         ret);
 106
 107         return ret;
 108 }
 109
 110 static int da9063_wdt_stop(struct watchdog_device *wdd)
 111 {
 112         struct da9063 *da9063 = watchdog_get_drvdata(wdd);
 113         int ret;
 114
 115         ret = da9063_wdt_disable_timer(da9063);
 116         if (ret)
 117                 dev_alert(da9063->dev, "Watchdog failed to stop (err = %d)\n",
 118                           ret);
 119
 120         return ret;
 121 }
 122
 123 static int da9063_wdt_ping(struct watchdog_device *wdd)
 124 {
 125         struct da9063 *da9063 = watchdog_get_drvdata(wdd);
 126         int ret;
 127
 128         /*
 129          * Prevent pings from occurring late in system poweroff/reboot sequence
 130          * and possibly locking out restart handler from accessing i2c bus.
 131          */
 132         if (system_state > SYSTEM_RUNNING)
 133                 return 0;
 134
 135         ret = regmap_write(da9063->regmap, DA9063_REG_CONTROL_F,
 136                            DA9063_WATCHDOG);
 137         if (ret)
 138                 dev_alert(da9063->dev, "Failed to ping the watchdog (err = %d)\n",
 139                           ret);
 140
 141         return ret;
 142 }
 143
 144 static int da9063_wdt_set_timeout(struct watchdog_device *wdd,
 145                                   unsigned int timeout)
 146 {
 147         struct da9063 *da9063 = watchdog_get_drvdata(wdd);
 148         int ret = 0;
 149
 150         /*
 151          * There are two cases when a set_timeout() will be called:
 152          * 1. The watchdog is off and someone wants to set the timeout for the
 153          *    further use.
 154          * 2. The watchdog is already running and a new timeout value should be
 155          *    set.
 156          *
 157          * The watchdog can't store a timeout value not equal zero without
 158          * enabling the watchdog, so the timeout must be buffered by the driver.
 159          */
 160         if (watchdog_active(wdd))
 161                 ret = da9063_wdt_update_timeout(da9063, timeout);
 162
 163         if (ret)
 164                 dev_err(da9063->dev, "Failed to set watchdog timeout (err = %d)\n",
 165                         ret);
 166         else
 167                 wdd->timeout = wdt_timeout[da9063_wdt_timeout_to_sel(timeout)];
 168
 169         return ret;
 170 }
 171
 172 static int da9063_wdt_restart(struct watchdog_device *wdd, unsigned long action,
 173                               void *data)
 174 {
 175         struct da9063 *da9063 = watchdog_get_drvdata(wdd);
 176         struct i2c_client *client = to_i2c_client(da9063->dev);
 177         union i2c_smbus_data msg;
 178         int ret;
 179
 180         /*
 181          * Don't use regmap because it is not atomic safe. Additionally, use
 182          * unlocked flavor of i2c_smbus_xfer to avoid scenario where i2c bus
 183          * might previously be locked by some process unable to release the
 184          * lock due to interrupts already being disabled at this late stage.
 185          */
 186         msg.byte = DA9063_SHUTDOWN;
 187         ret = __i2c_smbus_xfer(client->adapter, client->addr, client->flags,
 188                         I2C_SMBUS_WRITE, DA9063_REG_CONTROL_F,
 189                         I2C_SMBUS_BYTE_DATA, &msg);
 190
 191         if (ret < 0)
 192                 dev_alert(da9063->dev, "Failed to shutdown (err = %d)\n",
 193                           ret);
 194
 195         /* wait for reset to assert... */
 196         mdelay(500);
 197
 198         return ret;
 199 }
 200
 201 static const struct watchdog_info da9063_watchdog_info = {
 202         .options = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING,
 203         .identity = "DA9063 Watchdog",
 204 };
 205
 206 static const struct watchdog_ops da9063_watchdog_ops = {
 207         .owner = THIS_MODULE,
 208         .start = da9063_wdt_start,
 209         .stop = da9063_wdt_stop,
 210         .ping = da9063_wdt_ping,
 211         .set_timeout = da9063_wdt_set_timeout,
 212         .restart = da9063_wdt_restart,
 213 };
 214
 215 static int da9063_wdt_probe(struct platform_device *pdev)
 216 {
 217         struct device *dev = &pdev->dev;
 218         struct da9063 *da9063;
 219         struct watchdog_device *wdd;
 220         unsigned int timeout;
 221
 222         if (!dev->parent)
 223                 return -EINVAL;
 224
 225         da9063 = dev_get_drvdata(dev->parent);
 226         if (!da9063)
 227                 return -EINVAL;
 228
 229         wdd = devm_kzalloc(dev, sizeof(*wdd), GFP_KERNEL);
 230         if (!wdd)
 231                 return -ENOMEM;
 232
 233         use_sw_pm = device_property_present(dev, "dlg,use-sw-pm");
 234
 235         wdd->info = &da9063_watchdog_info;
 236         wdd->ops = &da9063_watchdog_ops;
 237         wdd->min_timeout = DA9063_WDT_MIN_TIMEOUT;
 238         wdd->max_timeout = DA9063_WDT_MAX_TIMEOUT;
 239         wdd->min_hw_heartbeat_ms = DA9063_RESET_PROTECTION_MS;
 240         wdd->parent = dev;
 241         wdd->status = WATCHDOG_NOWAYOUT_INIT_STATUS;
 242
 243         watchdog_set_restart_priority(wdd, 128);
 244         watchdog_set_drvdata(wdd, da9063);
 245         dev_set_drvdata(dev, wdd);
 246
 247         wdd->timeout = DA9063_WDG_TIMEOUT;
 248
 249         /* Use pre-configured timeout if watchdog is already running. */
 250         timeout = da9063_wdt_read_timeout(da9063);
 251         if (timeout)
 252                 wdd->timeout = timeout;
 253
 254         /* Set timeout, maybe override it with DT value, scale it */
 255         watchdog_init_timeout(wdd, 0, dev);
 256         da9063_wdt_set_timeout(wdd, wdd->timeout);
 257
 258         /* Update timeout if the watchdog is already running. */
 259         if (timeout) {
 260                 da9063_wdt_update_timeout(da9063, wdd->timeout);
 261                 set_bit(WDOG_HW_RUNNING, &wdd->status);
 262         }
 263
 264         return devm_watchdog_register_device(dev, wdd);
 265 }
 266
 267 static int __maybe_unused da9063_wdt_suspend(struct device *dev)
 268 {
 269         struct watchdog_device *wdd = dev_get_drvdata(dev);
 270
 271         if (!use_sw_pm)
 272                 return 0;
 273
 274         if (watchdog_active(wdd))
 275                 return da9063_wdt_stop(wdd);
 276
 277         return 0;
 278 }
 279
 280 static int __maybe_unused da9063_wdt_resume(struct device *dev)
 281 {
 282         struct watchdog_device *wdd = dev_get_drvdata(dev);
 283
 284         if (!use_sw_pm)
 285                 return 0;
 286
 287         if (watchdog_active(wdd))
 288                 return da9063_wdt_start(wdd);
 289
 290         return 0;
 291 }
 292
 293 static SIMPLE_DEV_PM_OPS(da9063_wdt_pm_ops,
 294                         da9063_wdt_suspend, da9063_wdt_resume);
 295
 296 static struct platform_driver da9063_wdt_driver = {
 297         .probe = da9063_wdt_probe,
 298         .driver = {
 299                 .name = DA9063_DRVNAME_WATCHDOG,
 300                 .pm = &da9063_wdt_pm_ops,
 301         },
 302 };
 303 module_platform_driver(da9063_wdt_driver);
 304
 305 MODULE_AUTHOR("Mariusz Wojtasik <mariusz.wojtasik@diasemi.com>");
 306 MODULE_DESCRIPTION("Watchdog driver for Dialog DA9063");
 307 MODULE_LICENSE("GPL");
 308 MODULE_ALIAS("platform:" DA9063_DRVNAME_WATCHDOG);