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