drivers/watchdog/da9055_wdt.c

   1 /*
   2  * System monitoring driver for DA9055 PMICs.
   3  *
   4  * Copyright(c) 2012 Dialog Semiconductor Ltd.
   5  *
   6  * Author: David Dajun Chen <dchen@diasemi.com>
   7  *
   8  * This program is free software; you can redistribute it and/or modify
   9  * it under the terms of the GNU General Public License as published by
  10  * the Free Software Foundation; either version 2 of the License, or
  11  * (at your option) any later version.
  12  *
  13  */
  14
  15 #include <linux/module.h>
  16 #include <linux/types.h>
  17 #include <linux/kernel.h>
  18 #include <linux/slab.h>
  19 #include <linux/platform_device.h>
  20 #include <linux/watchdog.h>
  21 #include <linux/delay.h>
  22
  23 #include <linux/mfd/da9055/core.h>
  24 #include <linux/mfd/da9055/reg.h>
  25
  26 static bool nowayout = WATCHDOG_NOWAYOUT;
  27 module_param(nowayout, bool, 0);
  28 MODULE_PARM_DESC(nowayout,
  29                  "Watchdog cannot be stopped once started (default="
  30                  __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
  31
  32 #define DA9055_DEF_TIMEOUT      4
  33 #define DA9055_TWDMIN           256
  34
  35 struct da9055_wdt_data {
  36         struct watchdog_device wdt;
  37         struct da9055 *da9055;
  38 };
  39
  40 static const struct {
  41         u8 reg_val;
  42         int user_time;  /* In seconds */
  43 } da9055_wdt_maps[] = {
  44         { 0, 0 },
  45         { 1, 2 },
  46         { 2, 4 },
  47         { 3, 8 },
  48         { 4, 16 },
  49         { 5, 32 },
  50         { 5, 33 },  /* Actual time  32.768s so included both 32s and 33s */
  51         { 6, 65 },
  52         { 6, 66 },  /* Actual time 65.536s so include both, 65s and 66s */
  53         { 7, 131 },
  54 };
  55
  56 static int da9055_wdt_set_timeout(struct watchdog_device *wdt_dev,
  57                                   unsigned int timeout)
  58 {
  59         struct da9055_wdt_data *driver_data = watchdog_get_drvdata(wdt_dev);
  60         struct da9055 *da9055 = driver_data->da9055;
  61         int ret, i;
  62
  63         for (i = 0; i < ARRAY_SIZE(da9055_wdt_maps); i++)
  64                 if (da9055_wdt_maps[i].user_time == timeout)
  65                         break;
  66
  67         if (i == ARRAY_SIZE(da9055_wdt_maps))
  68                 ret = -EINVAL;
  69         else
  70                 ret = da9055_reg_update(da9055, DA9055_REG_CONTROL_B,
  71                                         DA9055_TWDSCALE_MASK,
  72                                         da9055_wdt_maps[i].reg_val <<
  73                                         DA9055_TWDSCALE_SHIFT);
  74         if (ret < 0) {
  75                 dev_err(da9055->dev,
  76                         "Failed to update timescale bit, %d\n", ret);
  77                 return ret;
  78         }
  79
  80         wdt_dev->timeout = timeout;
  81
  82         return 0;
  83 }
  84
  85 static int da9055_wdt_ping(struct watchdog_device *wdt_dev)
  86 {
  87         struct da9055_wdt_data *driver_data = watchdog_get_drvdata(wdt_dev);
  88         struct da9055 *da9055 = driver_data->da9055;
  89
  90         /*
  91          * We have a minimum time for watchdog window called TWDMIN. A write
  92          * to the watchdog before this elapsed time will cause an error.
  93          */
  94         mdelay(DA9055_TWDMIN);
  95
  96         /* Reset the watchdog timer */
  97         return da9055_reg_update(da9055, DA9055_REG_CONTROL_E,
  98                                  DA9055_WATCHDOG_MASK, 1);
  99 }
 100
 101 static int da9055_wdt_start(struct watchdog_device *wdt_dev)
 102 {
 103         return da9055_wdt_set_timeout(wdt_dev, wdt_dev->timeout);
 104 }
 105
 106 static int da9055_wdt_stop(struct watchdog_device *wdt_dev)
 107 {
 108         return da9055_wdt_set_timeout(wdt_dev, 0);
 109 }
 110
 111 static const struct watchdog_info da9055_wdt_info = {
 112         .options        = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING,
 113         .identity       = "DA9055 Watchdog",
 114 };
 115
 116 static const struct watchdog_ops da9055_wdt_ops = {
 117         .owner = THIS_MODULE,
 118         .start = da9055_wdt_start,
 119         .stop = da9055_wdt_stop,
 120         .ping = da9055_wdt_ping,
 121         .set_timeout = da9055_wdt_set_timeout,
 122 };
 123
 124 static int da9055_wdt_probe(struct platform_device *pdev)
 125 {
 126         struct da9055 *da9055 = dev_get_drvdata(pdev->dev.parent);
 127         struct da9055_wdt_data *driver_data;
 128         struct watchdog_device *da9055_wdt;
 129         int ret;
 130
 131         driver_data = devm_kzalloc(&pdev->dev, sizeof(*driver_data),
 132                                    GFP_KERNEL);
 133         if (!driver_data)
 134                 return -ENOMEM;
 135
 136         driver_data->da9055 = da9055;
 137
 138         da9055_wdt = &driver_data->wdt;
 139
 140         da9055_wdt->timeout = DA9055_DEF_TIMEOUT;
 141         da9055_wdt->info = &da9055_wdt_info;
 142         da9055_wdt->ops = &da9055_wdt_ops;
 143         da9055_wdt->parent = &pdev->dev;
 144         watchdog_set_nowayout(da9055_wdt, nowayout);
 145         watchdog_set_drvdata(da9055_wdt, driver_data);
 146
 147         ret = da9055_wdt_stop(da9055_wdt);
 148         if (ret < 0) {
 149                 dev_err(&pdev->dev, "Failed to stop watchdog, %d\n", ret);
 150                 return ret;
 151         }
 152
 153         ret = devm_watchdog_register_device(&pdev->dev, &driver_data->wdt);
 154         if (ret != 0)
 155                 dev_err(da9055->dev, "watchdog_register_device() failed: %d\n",
 156                         ret);
 157
 158         return ret;
 159 }
 160
 161 static struct platform_driver da9055_wdt_driver = {
 162         .probe = da9055_wdt_probe,
 163         .driver = {
 164                 .name   = "da9055-watchdog",
 165         },
 166 };
 167
 168 module_platform_driver(da9055_wdt_driver);
 169
 170 MODULE_AUTHOR("David Dajun Chen <dchen@diasemi.com>");
 171 MODULE_DESCRIPTION("DA9055 watchdog");
 172 MODULE_LICENSE("GPL");
 173 MODULE_ALIAS("platform:da9055-watchdog");