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 <kernel@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/kernel.h>
  13 #include <linux/module.h>
  14 #include <linux/watchdog.h>
  15 #include <linux/platform_device.h>
  16 #include <linux/stmp3xxx_rtc_wdt.h>
  17
  18 #define WDOG_TICK_RATE 1000 /* 1 kHz clock */
  19 #define STMP3XXX_DEFAULT_TIMEOUT 19
  20 #define STMP3XXX_MAX_TIMEOUT (UINT_MAX / WDOG_TICK_RATE)
  21
  22 static int heartbeat = STMP3XXX_DEFAULT_TIMEOUT;
  23 module_param(heartbeat, uint, 0);
  24 MODULE_PARM_DESC(heartbeat, "Watchdog heartbeat period in seconds from 1 to "
  25                  __MODULE_STRING(STMP3XXX_MAX_TIMEOUT) ", default "
  26                  __MODULE_STRING(STMP3XXX_DEFAULT_TIMEOUT));
  27
  28 static int wdt_start(struct watchdog_device *wdd)
  29 {
  30         struct device *dev = watchdog_get_drvdata(wdd);
  31         struct stmp3xxx_wdt_pdata *pdata = dev_get_platdata(dev);
  32
  33         pdata->wdt_set_timeout(dev->parent, wdd->timeout * WDOG_TICK_RATE);
  34         return 0;
  35 }
  36
  37 static int wdt_stop(struct watchdog_device *wdd)
  38 {
  39         struct device *dev = watchdog_get_drvdata(wdd);
  40         struct stmp3xxx_wdt_pdata *pdata = dev_get_platdata(dev);
  41
  42         pdata->wdt_set_timeout(dev->parent, 0);
  43         return 0;
  44 }
  45
  46 static int wdt_set_timeout(struct watchdog_device *wdd, unsigned new_timeout)
  47 {
  48         wdd->timeout = new_timeout;
  49         return wdt_start(wdd);
  50 }
  51
  52 static const struct watchdog_info stmp3xxx_wdt_ident = {
  53         .options = WDIOF_MAGICCLOSE | WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING,
  54         .identity = "STMP3XXX RTC Watchdog",
  55 };
  56
  57 static const struct watchdog_ops stmp3xxx_wdt_ops = {
  58         .owner = THIS_MODULE,
  59         .start = wdt_start,
  60         .stop = wdt_stop,
  61         .set_timeout = wdt_set_timeout,
  62 };
  63
  64 static struct watchdog_device stmp3xxx_wdd = {
  65         .info = &stmp3xxx_wdt_ident,
  66         .ops = &stmp3xxx_wdt_ops,
  67         .min_timeout = 1,
  68         .max_timeout = STMP3XXX_MAX_TIMEOUT,
  69         .status = WATCHDOG_NOWAYOUT_INIT_STATUS,
  70 };
  71
  72 static int stmp3xxx_wdt_probe(struct platform_device *pdev)
  73 {
  74         int ret;
  75
  76         watchdog_set_drvdata(&stmp3xxx_wdd, &pdev->dev);
  77
  78         stmp3xxx_wdd.timeout = clamp_t(unsigned, heartbeat, 1, STMP3XXX_MAX_TIMEOUT);
  79         stmp3xxx_wdd.parent = &pdev->dev;
  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 int __maybe_unused stmp3xxx_wdt_suspend(struct device *dev)
  99 {
 100         struct watchdog_device *wdd = &stmp3xxx_wdd;
 101
 102         if (watchdog_active(wdd))
 103                 return wdt_stop(wdd);
 104
 105         return 0;
 106 }
 107
 108 static int __maybe_unused stmp3xxx_wdt_resume(struct device *dev)
 109 {
 110         struct watchdog_device *wdd = &stmp3xxx_wdd;
 111
 112         if (watchdog_active(wdd))
 113                 return wdt_start(wdd);
 114
 115         return 0;
 116 }
 117
 118 static SIMPLE_DEV_PM_OPS(stmp3xxx_wdt_pm_ops,
 119                          stmp3xxx_wdt_suspend, stmp3xxx_wdt_resume);
 120
 121 static struct platform_driver stmp3xxx_wdt_driver = {
 122         .driver = {
 123                 .name = "stmp3xxx_rtc_wdt",
 124                 .pm = &stmp3xxx_wdt_pm_ops,
 125         },
 126         .probe = stmp3xxx_wdt_probe,
 127         .remove = stmp3xxx_wdt_remove,
 128 };
 129 module_platform_driver(stmp3xxx_wdt_driver);
 130
 131 MODULE_DESCRIPTION("STMP3XXX RTC Watchdog Driver");
 132 MODULE_LICENSE("GPL v2");
 133 MODULE_AUTHOR("Wolfram Sang <kernel@pengutronix.de>");