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/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
  24 static int heartbeat = STMP3XXX_DEFAULT_TIMEOUT;
  25 module_param(heartbeat, uint, 0);
  26 MODULE_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
  30 static 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
  39 static 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
  48 static int wdt_set_timeout(struct watchdog_device *wdd, unsigned new_timeout)
  49 {
  50         wdd->timeout = new_timeout;
  51         return wdt_start(wdd);
  52 }
  53
  54 static const struct watchdog_info stmp3xxx_wdt_ident = {
  55         .options = WDIOF_MAGICCLOSE | WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING,
  56         .identity = "STMP3XXX RTC Watchdog",
  57 };
  58
  59 static 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
  66 static 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
  74 static 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
  93 static int stmp3xxx_wdt_remove(struct platform_device *pdev)
  94 {
  95         watchdog_unregister_device(&stmp3xxx_wdd);
  96         return 0;
  97 }
  98
  99 static 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 };
 106 module_platform_driver(stmp3xxx_wdt_driver);
 107
 108 MODULE_DESCRIPTION("STMP3XXX RTC Watchdog Driver");
 109 MODULE_LICENSE("GPL v2");
 110 MODULE_AUTHOR("Wolfram Sang <w.sang@pengutronix.de>");
 111 MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);