linux/drivers/watchdog/da9055_wdt.c
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   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
  26static bool nowayout = WATCHDOG_NOWAYOUT;
  27module_param(nowayout, bool, 0);
  28MODULE_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
  35struct da9055_wdt_data {
  36        struct watchdog_device wdt;
  37        struct da9055 *da9055;
  38        struct kref kref;
  39};
  40
  41static 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
  57static 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
  86static 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
 102static void da9055_wdt_release_resources(struct kref *r)
 103{
 104}
 105
 106static 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
 113static 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
 120static int da9055_wdt_start(struct watchdog_device *wdt_dev)
 121{
 122        return da9055_wdt_set_timeout(wdt_dev, wdt_dev->timeout);
 123}
 124
 125static int da9055_wdt_stop(struct watchdog_device *wdt_dev)
 126{
 127        return da9055_wdt_set_timeout(wdt_dev, 0);
 128}
 129
 130static struct watchdog_info da9055_wdt_info = {
 131        .options        = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING,
 132        .identity       = "DA9055 Watchdog",
 133};
 134
 135static 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
 145static 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                dev_err(da9055->dev, "Failed to allocate watchdog device\n");
 156                return -ENOMEM;
 157        }
 158
 159        driver_data->da9055 = da9055;
 160
 161        da9055_wdt = &driver_data->wdt;
 162
 163        da9055_wdt->timeout = DA9055_DEF_TIMEOUT;
 164        da9055_wdt->info = &da9055_wdt_info;
 165        da9055_wdt->ops = &da9055_wdt_ops;
 166        watchdog_set_nowayout(da9055_wdt, nowayout);
 167        watchdog_set_drvdata(da9055_wdt, driver_data);
 168
 169        kref_init(&driver_data->kref);
 170
 171        ret = da9055_wdt_stop(da9055_wdt);
 172        if (ret < 0) {
 173                dev_err(&pdev->dev, "Failed to stop watchdog, %d\n", ret);
 174                goto err;
 175        }
 176
 177        dev_set_drvdata(&pdev->dev, driver_data);
 178
 179        ret = watchdog_register_device(&driver_data->wdt);
 180        if (ret != 0)
 181                dev_err(da9055->dev, "watchdog_register_device() failed: %d\n",
 182                        ret);
 183
 184err:
 185        return ret;
 186}
 187
 188static int da9055_wdt_remove(struct platform_device *pdev)
 189{
 190        struct da9055_wdt_data *driver_data = dev_get_drvdata(&pdev->dev);
 191
 192        watchdog_unregister_device(&driver_data->wdt);
 193        kref_put(&driver_data->kref, da9055_wdt_release_resources);
 194
 195        return 0;
 196}
 197
 198static struct platform_driver da9055_wdt_driver = {
 199        .probe = da9055_wdt_probe,
 200        .remove = da9055_wdt_remove,
 201        .driver = {
 202                .name   = "da9055-watchdog",
 203        },
 204};
 205
 206module_platform_driver(da9055_wdt_driver);
 207
 208MODULE_AUTHOR("David Dajun Chen <dchen@diasemi.com>");
 209MODULE_DESCRIPTION("DA9055 watchdog");
 210MODULE_LICENSE("GPL");
 211MODULE_ALIAS("platform:da9055-watchdog");
 212
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