drivers/watchdog/stmp3xxx_rtc_wdt.c

   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/watchdog.h>
  16 #include <linux/platform_device.h>
  17 #include <linux/stmp3xxx_rtc_wdt.h>
  18
  19 #define WDOG_TICK_RATE 1000 /* 1 kHz clock */
  20 #define STMP3XXX_DEFAULT_TIMEOUT 19
  21 #define STMP3XXX_MAX_TIMEOUT (UINT_MAX / WDOG_TICK_RATE)
  22
  23 static int heartbeat = STMP3XXX_DEFAULT_TIMEOUT;
  24 module_param(heartbeat, uint, 0);
  25 MODULE_PARM_DESC(heartbeat, "Watchdog heartbeat period in seconds from 1 to "
  26                  __MODULE_STRING(STMP3XXX_MAX_TIMEOUT) ", default "
  27                  __MODULE_STRING(STMP3XXX_DEFAULT_TIMEOUT));
  28
  29 static int wdt_start(struct watchdog_device *wdd)
  30 {
  31         struct device *dev = watchdog_get_drvdata(wdd);
  32         struct stmp3xxx_wdt_pdata *pdata = dev_get_platdata(dev);
  33
  34         pdata->wdt_set_timeout(dev->parent, wdd->timeout * WDOG_TICK_RATE);
  35         return 0;
  36 }
  37
  38 static int wdt_stop(struct watchdog_device *wdd)
  39 {
  40         struct device *dev = watchdog_get_drvdata(wdd);
  41         struct stmp3xxx_wdt_pdata *pdata = dev_get_platdata(dev);
  42
  43         pdata->wdt_set_timeout(dev->parent, 0);
  44         return 0;
  45 }
  46
  47 static int wdt_set_timeout(struct watchdog_device *wdd, unsigned new_timeout)
  48 {
  49         wdd->timeout = new_timeout;
  50         return wdt_start(wdd);
  51 }
  52
  53 static const struct watchdog_info stmp3xxx_wdt_ident = {
  54         .options = WDIOF_MAGICCLOSE | WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING,
  55         .identity = "STMP3XXX RTC Watchdog",
  56 };
  57
  58 static const struct watchdog_ops stmp3xxx_wdt_ops = {
  59         .owner = THIS_MODULE,
  60         .start = wdt_start,
  61         .stop = wdt_stop,
  62         .set_timeout = wdt_set_timeout,
  63 };
  64
  65 static struct watchdog_device stmp3xxx_wdd = {
  66         .info = &stmp3xxx_wdt_ident,
  67         .ops = &stmp3xxx_wdt_ops,
  68         .min_timeout = 1,
  69         .max_timeout = STMP3XXX_MAX_TIMEOUT,
  70         .status = WATCHDOG_NOWAYOUT_INIT_STATUS,
  71 };
  72
  73 static int stmp3xxx_wdt_probe(struct platform_device *pdev)
  74 {
  75         int ret;
  76
  77         watchdog_set_drvdata(&stmp3xxx_wdd, &pdev->dev);
  78
  79         stmp3xxx_wdd.timeout = clamp_t(unsigned, heartbeat, 1, STMP3XXX_MAX_TIMEOUT);
  80
  81         ret = watchdog_register_device(&stmp3xxx_wdd);
  82         if (ret < 0) {
  83                 dev_err(&pdev->dev, "cannot register watchdog device\n");
  84                 return ret;
  85         }
  86
  87         dev_info(&pdev->dev, "initialized watchdog with heartbeat %ds\n",
  88                         stmp3xxx_wdd.timeout);
  89         return 0;
  90 }
  91
  92 static int stmp3xxx_wdt_remove(struct platform_device *pdev)
  93 {
  94         watchdog_unregister_device(&stmp3xxx_wdd);
  95         return 0;
  96 }
  97
  98 static struct platform_driver stmp3xxx_wdt_driver = {
  99         .driver = {
 100                 .name = "stmp3xxx_rtc_wdt",
 101         },
 102         .probe = stmp3xxx_wdt_probe,
 103         .remove = stmp3xxx_wdt_remove,
 104 };
 105 module_platform_driver(stmp3xxx_wdt_driver);
 106
 107 MODULE_DESCRIPTION("STMP3XXX RTC Watchdog Driver");
 108 MODULE_LICENSE("GPL v2");
 109 MODULE_AUTHOR("Wolfram Sang <w.sang@pengutronix.de>");