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        struct da9052_wdt_data *driver_data =
  57                container_of(r, struct da9052_wdt_data, kref);
  58
  59        kfree(driver_data);
  60}
  61
  62static int da9052_wdt_set_timeout(struct watchdog_device *wdt_dev,
  63                                  unsigned int timeout)
  64{
  65        struct da9052_wdt_data *driver_data = watchdog_get_drvdata(wdt_dev);
  66        struct da9052 *da9052 = driver_data->da9052;
  67        int ret, i;
  68
  69        /*
  70         * Disable the Watchdog timer before setting
  71         * new time out.
  72         */
  73        ret = da9052_reg_update(da9052, DA9052_CONTROL_D_REG,
  74                                DA9052_CONTROLD_TWDSCALE, 0);
  75        if (ret < 0) {
  76                dev_err(da9052->dev, "Failed to disable watchdog bit, %d\n",
  77                        ret);
  78                return ret;
  79        }
  80        if (timeout) {
  81                /*
  82                 * To change the timeout, da9052 needs to
  83                 * be disabled for at least 150 us.
  84                 */
  85                udelay(150);
  86
  87                /* Set the desired timeout */
  88                for (i = 0; i < ARRAY_SIZE(da9052_wdt_maps); i++)
  89                        if (da9052_wdt_maps[i].time == timeout)
  90                                break;
  91
  92                if (i == ARRAY_SIZE(da9052_wdt_maps))
  93                        ret = -EINVAL;
  94                else
  95                        ret = da9052_reg_update(da9052, DA9052_CONTROL_D_REG,
  96                                                DA9052_CONTROLD_TWDSCALE,
  97                                                da9052_wdt_maps[i].reg_val);
  98                if (ret < 0) {
  99                        dev_err(da9052->dev,
 100                                "Failed to update timescale bit, %d\n", ret);
 101                        return ret;
 102                }
 103
 104                wdt_dev->timeout = timeout;
 105                driver_data->jpast = jiffies;
 106        }
 107
 108        return 0;
 109}
 110
 111static void da9052_wdt_ref(struct watchdog_device *wdt_dev)
 112{
 113        struct da9052_wdt_data *driver_data = watchdog_get_drvdata(wdt_dev);
 114
 115        kref_get(&driver_data->kref);
 116}
 117
 118static void da9052_wdt_unref(struct watchdog_device *wdt_dev)
 119{
 120        struct da9052_wdt_data *driver_data = watchdog_get_drvdata(wdt_dev);
 121
 122        kref_put(&driver_data->kref, da9052_wdt_release_resources);
 123}
 124
 125static int da9052_wdt_start(struct watchdog_device *wdt_dev)
 126{
 127        return da9052_wdt_set_timeout(wdt_dev, wdt_dev->timeout);
 128}
 129
 130static int da9052_wdt_stop(struct watchdog_device *wdt_dev)
 131{
 132        return da9052_wdt_set_timeout(wdt_dev, 0);
 133}
 134
 135static int da9052_wdt_ping(struct watchdog_device *wdt_dev)
 136{
 137        struct da9052_wdt_data *driver_data = watchdog_get_drvdata(wdt_dev);
 138        struct da9052 *da9052 = driver_data->da9052;
 139        unsigned long msec, jnow = jiffies;
 140        int ret;
 141
 142        /*
 143         * We have a minimum time for watchdog window called TWDMIN. A write
 144         * to the watchdog before this elapsed time should cause an error.
 145         */
 146        msec = (jnow - driver_data->jpast) * 1000/HZ;
 147        if (msec < DA9052_TWDMIN)
 148                mdelay(msec);
 149
 150        /* Reset the watchdog timer */
 151        ret = da9052_reg_update(da9052, DA9052_CONTROL_D_REG,
 152                                DA9052_CONTROLD_WATCHDOG, 1 << 7);
 153        if (ret < 0)
 154                goto err_strobe;
 155
 156        /*
 157         * FIXME: Reset the watchdog core, in general PMIC
 158         * is supposed to do this
 159         */
 160        ret = da9052_reg_update(da9052, DA9052_CONTROL_D_REG,
 161                                DA9052_CONTROLD_WATCHDOG, 0 << 7);
 162err_strobe:
 163        return ret;
 164}
 165
 166static struct watchdog_info da9052_wdt_info = {
 167        .options        = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING,
 168        .identity       = "DA9052 Watchdog",
 169};
 170
 171static const struct watchdog_ops da9052_wdt_ops = {
 172        .owner = THIS_MODULE,
 173        .start = da9052_wdt_start,
 174        .stop = da9052_wdt_stop,
 175        .ping = da9052_wdt_ping,
 176        .set_timeout = da9052_wdt_set_timeout,
 177        .ref = da9052_wdt_ref,
 178        .unref = da9052_wdt_unref,
 179};
 180
 181
 182static int __devinit da9052_wdt_probe(struct platform_device *pdev)
 183{
 184        struct da9052 *da9052 = dev_get_drvdata(pdev->dev.parent);
 185        struct da9052_wdt_data *driver_data;
 186        struct watchdog_device *da9052_wdt;
 187        int ret;
 188
 189        driver_data = devm_kzalloc(&pdev->dev, sizeof(*driver_data),
 190                                   GFP_KERNEL);
 191        if (!driver_data) {
 192                dev_err(da9052->dev, "Unable to alloacate watchdog device\n");
 193                ret = -ENOMEM;
 194                goto err;
 195        }
 196        driver_data->da9052 = da9052;
 197
 198        da9052_wdt = &driver_data->wdt;
 199
 200        da9052_wdt->timeout = DA9052_DEF_TIMEOUT;
 201        da9052_wdt->info = &da9052_wdt_info;
 202        da9052_wdt->ops = &da9052_wdt_ops;
 203        watchdog_set_drvdata(da9052_wdt, driver_data);
 204
 205        kref_init(&driver_data->kref);
 206
 207        ret = da9052_reg_update(da9052, DA9052_CONTROL_D_REG,
 208                                DA9052_CONTROLD_TWDSCALE, 0);
 209        if (ret < 0) {
 210                dev_err(&pdev->dev, "Failed to disable watchdog bits, %d\n",
 211                        ret);
 212                goto err;
 213        }
 214
 215        ret = watchdog_register_device(&driver_data->wdt);
 216        if (ret != 0) {
 217                dev_err(da9052->dev, "watchdog_register_device() failed: %d\n",
 218                        ret);
 219                goto err;
 220        }
 221
 222        dev_set_drvdata(&pdev->dev, driver_data);
 223err:
 224        return ret;
 225}
 226
 227static int __devexit da9052_wdt_remove(struct platform_device *pdev)
 228{
 229        struct da9052_wdt_data *driver_data = dev_get_drvdata(&pdev->dev);
 230
 231        watchdog_unregister_device(&driver_data->wdt);
 232        kref_put(&driver_data->kref, da9052_wdt_release_resources);
 233
 234        return 0;
 235}
 236
 237static struct platform_driver da9052_wdt_driver = {
 238        .probe = da9052_wdt_probe,
 239        .remove = __devexit_p(da9052_wdt_remove),
 240        .driver = {
 241                .name   = "da9052-watchdog",
 242        },
 243};
 244
 245module_platform_driver(da9052_wdt_driver);
 246
 247MODULE_AUTHOR("Anthony Olech <Anthony.Olech@diasemi.com>");
 248MODULE_DESCRIPTION("DA9052 SM Device Driver");
 249MODULE_LICENSE("GPL");
 250MODULE_ALIAS("platform:da9052-watchdog");
 251
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