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         struct kref kref;
  39 };
  40
  41 static const struct {
  42         u8 reg_val;
  43         int user_time;  /* In seconds */
  44 } da9055_wdt_maps[] = {
  45         { 0, 0 },
  46         { 1, 2 },
  47         { 2, 4 },
  48         { 3, 8 },
  49         { 4, 16 },
  50         { 5, 32 },
  51         { 5, 33 },  /* Actual time  32.768s so included both 32s and 33s */
  52         { 6, 65 },
  53         { 6, 66 },  /* Actual time 65.536s so include both, 65s and 66s */
  54         { 7, 131 },
  55 };
  56
  57 static int da9055_wdt_set_timeout(struct watchdog_device *wdt_dev,
  58                                   unsigned int timeout)
  59 {
  60         struct da9055_wdt_data *driver_data = watchdog_get_drvdata(wdt_dev);
  61         struct da9055 *da9055 = driver_data->da9055;
  62         int ret, i;
  63
  64         for (i = 0; i < ARRAY_SIZE(da9055_wdt_maps); i++)
  65                 if (da9055_wdt_maps[i].user_time == timeout)
  66                         break;
  67
  68         if (i == ARRAY_SIZE(da9055_wdt_maps))
  69                 ret = -EINVAL;
  70         else
  71                 ret = da9055_reg_update(da9055, DA9055_REG_CONTROL_B,
  72                                         DA9055_TWDSCALE_MASK,
  73                                         da9055_wdt_maps[i].reg_val <<
  74                                         DA9055_TWDSCALE_SHIFT);
  75         if (ret < 0) {
  76                 dev_err(da9055->dev,
  77                         "Failed to update timescale bit, %d\n", ret);
  78                 return ret;
  79         }
  80
  81         wdt_dev->timeout = timeout;
  82
  83         return 0;
  84 }
  85
  86 static int da9055_wdt_ping(struct watchdog_device *wdt_dev)
  87 {
  88         struct da9055_wdt_data *driver_data = watchdog_get_drvdata(wdt_dev);
  89         struct da9055 *da9055 = driver_data->da9055;
  90
  91         /*
  92          * We have a minimum time for watchdog window called TWDMIN. A write
  93          * to the watchdog before this elapsed time will cause an error.
  94          */
  95         mdelay(DA9055_TWDMIN);
  96
  97         /* Reset the watchdog timer */
  98         return da9055_reg_update(da9055, DA9055_REG_CONTROL_E,
  99                                  DA9055_WATCHDOG_MASK, 1);
 100 }
 101
 102 static void da9055_wdt_release_resources(struct kref *r)
 103 {
 104 }
 105
 106 static void da9055_wdt_ref(struct watchdog_device *wdt_dev)
 107 {
 108         struct da9055_wdt_data *driver_data = watchdog_get_drvdata(wdt_dev);
 109
 110         kref_get(&driver_data->kref);
 111 }
 112
 113 static void da9055_wdt_unref(struct watchdog_device *wdt_dev)
 114 {
 115         struct da9055_wdt_data *driver_data = watchdog_get_drvdata(wdt_dev);
 116
 117         kref_put(&driver_data->kref, da9055_wdt_release_resources);
 118 }
 119
 120 static int da9055_wdt_start(struct watchdog_device *wdt_dev)
 121 {
 122         return da9055_wdt_set_timeout(wdt_dev, wdt_dev->timeout);
 123 }
 124
 125 static int da9055_wdt_stop(struct watchdog_device *wdt_dev)
 126 {
 127         return da9055_wdt_set_timeout(wdt_dev, 0);
 128 }
 129
 130 static struct watchdog_info da9055_wdt_info = {
 131         .options        = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING,
 132         .identity       = "DA9055 Watchdog",
 133 };
 134
 135 static const struct watchdog_ops da9055_wdt_ops = {
 136         .owner = THIS_MODULE,
 137         .start = da9055_wdt_start,
 138         .stop = da9055_wdt_stop,
 139         .ping = da9055_wdt_ping,
 140         .set_timeout = da9055_wdt_set_timeout,
 141         .ref = da9055_wdt_ref,
 142         .unref = da9055_wdt_unref,
 143 };
 144
 145 static int da9055_wdt_probe(struct platform_device *pdev)
 146 {
 147         struct da9055 *da9055 = dev_get_drvdata(pdev->dev.parent);
 148         struct da9055_wdt_data *driver_data;
 149         struct watchdog_device *da9055_wdt;
 150         int ret;
 151
 152         driver_data = devm_kzalloc(&pdev->dev, sizeof(*driver_data),
 153                                    GFP_KERNEL);
 154         if (!driver_data)
 155                 return -ENOMEM;
 156
 157         driver_data->da9055 = da9055;
 158
 159         da9055_wdt = &driver_data->wdt;
 160
 161         da9055_wdt->timeout = DA9055_DEF_TIMEOUT;
 162         da9055_wdt->info = &da9055_wdt_info;
 163         da9055_wdt->ops = &da9055_wdt_ops;
 164         watchdog_set_nowayout(da9055_wdt, nowayout);
 165         watchdog_set_drvdata(da9055_wdt, driver_data);
 166
 167         kref_init(&driver_data->kref);
 168
 169         ret = da9055_wdt_stop(da9055_wdt);
 170         if (ret < 0) {
 171                 dev_err(&pdev->dev, "Failed to stop watchdog, %d\n", ret);
 172                 goto err;
 173         }
 174
 175         platform_set_drvdata(pdev, driver_data);
 176
 177         ret = watchdog_register_device(&driver_data->wdt);
 178         if (ret != 0)
 179                 dev_err(da9055->dev, "watchdog_register_device() failed: %d\n",
 180                         ret);
 181
 182 err:
 183         return ret;
 184 }
 185
 186 static int da9055_wdt_remove(struct platform_device *pdev)
 187 {
 188         struct da9055_wdt_data *driver_data = platform_get_drvdata(pdev);
 189
 190         watchdog_unregister_device(&driver_data->wdt);
 191         kref_put(&driver_data->kref, da9055_wdt_release_resources);
 192
 193         return 0;
 194 }
 195
 196 static struct platform_driver da9055_wdt_driver = {
 197         .probe = da9055_wdt_probe,
 198         .remove = da9055_wdt_remove,
 199         .driver = {
 200                 .name   = "da9055-watchdog",
 201         },
 202 };
 203
 204 module_platform_driver(da9055_wdt_driver);
 205
 206 MODULE_AUTHOR("David Dajun Chen <dchen@diasemi.com>");
 207 MODULE_DESCRIPTION("DA9055 watchdog");
 208 MODULE_LICENSE("GPL");
 209 MODULE_ALIAS("platform:da9055-watchdog");