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Linux/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/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 
 80         ret = watchdog_register_device(&stmp3xxx_wdd);
 81         if (ret < 0) {
 82                 dev_err(&pdev->dev, "cannot register watchdog device\n");
 83                 return ret;
 84         }
 85 
 86         dev_info(&pdev->dev, "initialized watchdog with heartbeat %ds\n",
 87                         stmp3xxx_wdd.timeout);
 88         return 0;
 89 }
 90 
 91 static int stmp3xxx_wdt_remove(struct platform_device *pdev)
 92 {
 93         watchdog_unregister_device(&stmp3xxx_wdd);
 94         return 0;
 95 }
 96 
 97 static struct platform_driver stmp3xxx_wdt_driver = {
 98         .driver = {
 99                 .name = "stmp3xxx_rtc_wdt",
100         },
101         .probe = stmp3xxx_wdt_probe,
102         .remove = stmp3xxx_wdt_remove,
103 };
104 module_platform_driver(stmp3xxx_wdt_driver);
105 
106 MODULE_DESCRIPTION("STMP3XXX RTC Watchdog Driver");
107 MODULE_LICENSE("GPL v2");
108 MODULE_AUTHOR("Wolfram Sang <w.sang@pengutronix.de>");
109 

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