linux/drivers/watchdog/da9052_wdt.c
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   1/*
   2 * System monitoring driver for DA9052 PMICs.
   3 *
   4 * Copyright(c) 2012 Dialog Semiconductor Ltd.
   5 *
   6 * Author: Anthony Olech <Anthony.Olech@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/delay.h>
  17#include <linux/uaccess.h>
  18#include <linux/platform_device.h>
  19#include <linux/time.h>
  20#include <linux/watchdog.h>
  21#include <linux/types.h>
  22#include <linux/kernel.h>
  23#include <linux/jiffies.h>
  24
  25#include <linux/mfd/da9052/reg.h>
  26#include <linux/mfd/da9052/da9052.h>
  27
  28#define DA9052_DEF_TIMEOUT      4
  29#define DA9052_TWDMIN           256
  30
  31struct da9052_wdt_data {
  32        struct watchdog_device wdt;
  33        struct da9052 *da9052;
  34        struct kref kref;
  35        unsigned long jpast;
  36};
  37
  38static const struct {
  39        u8 reg_val;
  40        int time;  /* Seconds */
  41} da9052_wdt_maps[] = {
  42        { 1, 2 },
  43        { 2, 4 },
  44        { 3, 8 },
  45        { 4, 16 },
  46        { 5, 32 },
  47        { 5, 33 },  /* Actual time  32.768s so included both 32s and 33s */
  48        { 6, 65 },
  49        { 6, 66 },  /* Actual time 65.536s so include both, 65s and 66s */
  50        { 7, 131 },
  51};
  52
  53
  54static void da9052_wdt_release_resources(struct kref *r)
  55{
  56}
  57
  58static int da9052_wdt_set_timeout(struct watchdog_device *wdt_dev,
  59                                  unsigned int timeout)
  60{
  61        struct da9052_wdt_data *driver_data = watchdog_get_drvdata(wdt_dev);
  62        struct da9052 *da9052 = driver_data->da9052;
  63        int ret, i;
  64
  65        /*
  66         * Disable the Watchdog timer before setting
  67         * new time out.
  68         */
  69        ret = da9052_reg_update(da9052, DA9052_CONTROL_D_REG,
  70                                DA9052_CONTROLD_TWDSCALE, 0);
  71        if (ret < 0) {
  72                dev_err(da9052->dev, "Failed to disable watchdog bit, %d\n",
  73                        ret);
  74                return ret;
  75        }
  76        if (timeout) {
  77                /*
  78                 * To change the timeout, da9052 needs to
  79                 * be disabled for at least 150 us.
  80                 */
  81                udelay(150);
  82
  83                /* Set the desired timeout */
  84                for (i = 0; i < ARRAY_SIZE(da9052_wdt_maps); i++)
  85                        if (da9052_wdt_maps[i].time == timeout)
  86                                break;
  87
  88                if (i == ARRAY_SIZE(da9052_wdt_maps))
  89                        ret = -EINVAL;
  90                else
  91                        ret = da9052_reg_update(da9052, DA9052_CONTROL_D_REG,
  92                                                DA9052_CONTROLD_TWDSCALE,
  93                                                da9052_wdt_maps[i].reg_val);
  94                if (ret < 0) {
  95                        dev_err(da9052->dev,
  96                                "Failed to update timescale bit, %d\n", ret);
  97                        return ret;
  98                }
  99
 100                wdt_dev->timeout = timeout;
 101                driver_data->jpast = jiffies;
 102        }
 103
 104        return 0;
 105}
 106
 107static void da9052_wdt_ref(struct watchdog_device *wdt_dev)
 108{
 109        struct da9052_wdt_data *driver_data = watchdog_get_drvdata(wdt_dev);
 110
 111        kref_get(&driver_data->kref);
 112}
 113
 114static void da9052_wdt_unref(struct watchdog_device *wdt_dev)
 115{
 116        struct da9052_wdt_data *driver_data = watchdog_get_drvdata(wdt_dev);
 117
 118        kref_put(&driver_data->kref, da9052_wdt_release_resources);
 119}
 120
 121static int da9052_wdt_start(struct watchdog_device *wdt_dev)
 122{
 123        return da9052_wdt_set_timeout(wdt_dev, wdt_dev->timeout);
 124}
 125
 126static int da9052_wdt_stop(struct watchdog_device *wdt_dev)
 127{
 128        return da9052_wdt_set_timeout(wdt_dev, 0);
 129}
 130
 131static int da9052_wdt_ping(struct watchdog_device *wdt_dev)
 132{
 133        struct da9052_wdt_data *driver_data = watchdog_get_drvdata(wdt_dev);
 134        struct da9052 *da9052 = driver_data->da9052;
 135        unsigned long msec, jnow = jiffies;
 136        int ret;
 137
 138        /*
 139         * We have a minimum time for watchdog window called TWDMIN. A write
 140         * to the watchdog before this elapsed time should cause an error.
 141         */
 142        msec = (jnow - driver_data->jpast) * 1000/HZ;
 143        if (msec < DA9052_TWDMIN)
 144                mdelay(msec);
 145
 146        /* Reset the watchdog timer */
 147        ret = da9052_reg_update(da9052, DA9052_CONTROL_D_REG,
 148                                DA9052_CONTROLD_WATCHDOG, 1 << 7);
 149        if (ret < 0)
 150                goto err_strobe;
 151
 152        /*
 153         * FIXME: Reset the watchdog core, in general PMIC
 154         * is supposed to do this
 155         */
 156        ret = da9052_reg_update(da9052, DA9052_CONTROL_D_REG,
 157                                DA9052_CONTROLD_WATCHDOG, 0 << 7);
 158err_strobe:
 159        return ret;
 160}
 161
 162static struct watchdog_info da9052_wdt_info = {
 163        .options        = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING,
 164        .identity       = "DA9052 Watchdog",
 165};
 166
 167static const struct watchdog_ops da9052_wdt_ops = {
 168        .owner = THIS_MODULE,
 169        .start = da9052_wdt_start,
 170        .stop = da9052_wdt_stop,
 171        .ping = da9052_wdt_ping,
 172        .set_timeout = da9052_wdt_set_timeout,
 173        .ref = da9052_wdt_ref,
 174        .unref = da9052_wdt_unref,
 175};
 176
 177
 178static int da9052_wdt_probe(struct platform_device *pdev)
 179{
 180        struct da9052 *da9052 = dev_get_drvdata(pdev->dev.parent);
 181        struct da9052_wdt_data *driver_data;
 182        struct watchdog_device *da9052_wdt;
 183        int ret;
 184
 185        driver_data = devm_kzalloc(&pdev->dev, sizeof(*driver_data),
 186                                   GFP_KERNEL);
 187        if (!driver_data) {
 188                dev_err(da9052->dev, "Unable to alloacate watchdog device\n");
 189                ret = -ENOMEM;
 190                goto err;
 191        }
 192        driver_data->da9052 = da9052;
 193
 194        da9052_wdt = &driver_data->wdt;
 195
 196        da9052_wdt->timeout = DA9052_DEF_TIMEOUT;
 197        da9052_wdt->info = &da9052_wdt_info;
 198        da9052_wdt->ops = &da9052_wdt_ops;
 199        watchdog_set_drvdata(da9052_wdt, driver_data);
 200
 201        kref_init(&driver_data->kref);
 202
 203        ret = da9052_reg_update(da9052, DA9052_CONTROL_D_REG,
 204                                DA9052_CONTROLD_TWDSCALE, 0);
 205        if (ret < 0) {
 206                dev_err(&pdev->dev, "Failed to disable watchdog bits, %d\n",
 207                        ret);
 208                goto err;
 209        }
 210
 211        ret = watchdog_register_device(&driver_data->wdt);
 212        if (ret != 0) {
 213                dev_err(da9052->dev, "watchdog_register_device() failed: %d\n",
 214                        ret);
 215                goto err;
 216        }
 217
 218        dev_set_drvdata(&pdev->dev, driver_data);
 219err:
 220        return ret;
 221}
 222
 223static int da9052_wdt_remove(struct platform_device *pdev)
 224{
 225        struct da9052_wdt_data *driver_data = dev_get_drvdata(&pdev->dev);
 226
 227        watchdog_unregister_device(&driver_data->wdt);
 228        kref_put(&driver_data->kref, da9052_wdt_release_resources);
 229
 230        return 0;
 231}
 232
 233static struct platform_driver da9052_wdt_driver = {
 234        .probe = da9052_wdt_probe,
 235        .remove = da9052_wdt_remove,
 236        .driver = {
 237                .name   = "da9052-watchdog",
 238        },
 239};
 240
 241module_platform_driver(da9052_wdt_driver);
 242
 243MODULE_AUTHOR("Anthony Olech <Anthony.Olech@diasemi.com>");
 244MODULE_DESCRIPTION("DA9052 SM Device Driver");
 245MODULE_LICENSE("GPL");
 246MODULE_ALIAS("platform:da9052-watchdog");
 247
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