linux/drivers/watchdog/stmp3xxx_rtc_wdt.c
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   1/*
   2 * Watchdog driver for the RTC based watchdog in STMP3xxx and i.MX23/28
   3 *
   4 * Author: Wolfram Sang <w.sang@pengutronix.de>
   5 *
   6 * Copyright (C) 2011-12 Wolfram Sang, Pengutronix
   7 *
   8 * This program is free software; you can redistribute it and/or modify it
   9 * under the terms of the GNU General Public License version 2 as published by
  10 * the Free Software Foundation.
  11 */
  12#include <linux/init.h>
  13#include <linux/kernel.h>
  14#include <linux/module.h>
  15#include <linux/miscdevice.h>
  16#include <linux/watchdog.h>
  17#include <linux/platform_device.h>
  18#include <linux/stmp3xxx_rtc_wdt.h>
  19
  20#define WDOG_TICK_RATE 1000 /* 1 kHz clock */
  21#define STMP3XXX_DEFAULT_TIMEOUT 19
  22#define STMP3XXX_MAX_TIMEOUT (UINT_MAX / WDOG_TICK_RATE)
  23
  24static int heartbeat = STMP3XXX_DEFAULT_TIMEOUT;
  25module_param(heartbeat, uint, 0);
  26MODULE_PARM_DESC(heartbeat, "Watchdog heartbeat period in seconds from 1 to "
  27                 __MODULE_STRING(STMP3XXX_MAX_TIMEOUT) ", default "
  28                 __MODULE_STRING(STMP3XXX_DEFAULT_TIMEOUT));
  29
  30static int wdt_start(struct watchdog_device *wdd)
  31{
  32        struct device *dev = watchdog_get_drvdata(wdd);
  33        struct stmp3xxx_wdt_pdata *pdata = dev->platform_data;
  34
  35        pdata->wdt_set_timeout(dev->parent, wdd->timeout * WDOG_TICK_RATE);
  36        return 0;
  37}
  38
  39static int wdt_stop(struct watchdog_device *wdd)
  40{
  41        struct device *dev = watchdog_get_drvdata(wdd);
  42        struct stmp3xxx_wdt_pdata *pdata = dev->platform_data;
  43
  44        pdata->wdt_set_timeout(dev->parent, 0);
  45        return 0;
  46}
  47
  48static int wdt_set_timeout(struct watchdog_device *wdd, unsigned new_timeout)
  49{
  50        wdd->timeout = new_timeout;
  51        return wdt_start(wdd);
  52}
  53
  54static const struct watchdog_info stmp3xxx_wdt_ident = {
  55        .options = WDIOF_MAGICCLOSE | WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING,
  56        .identity = "STMP3XXX RTC Watchdog",
  57};
  58
  59static const struct watchdog_ops stmp3xxx_wdt_ops = {
  60        .owner = THIS_MODULE,
  61        .start = wdt_start,
  62        .stop = wdt_stop,
  63        .set_timeout = wdt_set_timeout,
  64};
  65
  66static struct watchdog_device stmp3xxx_wdd = {
  67        .info = &stmp3xxx_wdt_ident,
  68        .ops = &stmp3xxx_wdt_ops,
  69        .min_timeout = 1,
  70        .max_timeout = STMP3XXX_MAX_TIMEOUT,
  71        .status = WATCHDOG_NOWAYOUT_INIT_STATUS,
  72};
  73
  74static int stmp3xxx_wdt_probe(struct platform_device *pdev)
  75{
  76        int ret;
  77
  78        watchdog_set_drvdata(&stmp3xxx_wdd, &pdev->dev);
  79
  80        stmp3xxx_wdd.timeout = clamp_t(unsigned, heartbeat, 1, STMP3XXX_MAX_TIMEOUT);
  81
  82        ret = watchdog_register_device(&stmp3xxx_wdd);
  83        if (ret < 0) {
  84                dev_err(&pdev->dev, "cannot register watchdog device\n");
  85                return ret;
  86        }
  87
  88        dev_info(&pdev->dev, "initialized watchdog with heartbeat %ds\n",
  89                        stmp3xxx_wdd.timeout);
  90        return 0;
  91}
  92
  93static int stmp3xxx_wdt_remove(struct platform_device *pdev)
  94{
  95        watchdog_unregister_device(&stmp3xxx_wdd);
  96        return 0;
  97}
  98
  99static struct platform_driver stmp3xxx_wdt_driver = {
 100        .driver = {
 101                .name = "stmp3xxx_rtc_wdt",
 102        },
 103        .probe = stmp3xxx_wdt_probe,
 104        .remove = stmp3xxx_wdt_remove,
 105};
 106module_platform_driver(stmp3xxx_wdt_driver);
 107
 108MODULE_DESCRIPTION("STMP3XXX RTC Watchdog Driver");
 109MODULE_LICENSE("GPL v2");
 110MODULE_AUTHOR("Wolfram Sang <w.sang@pengutronix.de>");
 111MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);
 112
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