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#include <linux/notifier.h>
 18#include <linux/reboot.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_get_platdata(dev);
 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_get_platdata(dev);
 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 wdt_notify_sys(struct notifier_block *nb, unsigned long code,
 75			  void *unused)
 76{
 77	switch (code) {
 78	case SYS_DOWN:	/* keep enabled, system might crash while going down */
 79		break;
 80	case SYS_HALT:	/* allow the system to actually halt */
 81	case SYS_POWER_OFF:
 82		wdt_stop(&stmp3xxx_wdd);
 83		break;
 84	}
 85
 86	return NOTIFY_DONE;
 87}
 88
 89static struct notifier_block wdt_notifier = {
 90	.notifier_call = wdt_notify_sys,
 91};
 92
 93static int stmp3xxx_wdt_probe(struct platform_device *pdev)
 94{
 95	int ret;
 96
 97	watchdog_set_drvdata(&stmp3xxx_wdd, &pdev->dev);
 98
 99	stmp3xxx_wdd.timeout = clamp_t(unsigned, heartbeat, 1, STMP3XXX_MAX_TIMEOUT);
100	stmp3xxx_wdd.parent = &pdev->dev;
101
102	ret = watchdog_register_device(&stmp3xxx_wdd);
103	if (ret < 0) {
104		dev_err(&pdev->dev, "cannot register watchdog device\n");
105		return ret;
106	}
107
108	if (register_reboot_notifier(&wdt_notifier))
109		dev_warn(&pdev->dev, "cannot register reboot notifier\n");
110
111	dev_info(&pdev->dev, "initialized watchdog with heartbeat %ds\n",
112			stmp3xxx_wdd.timeout);
113	return 0;
114}
115
116static int stmp3xxx_wdt_remove(struct platform_device *pdev)
117{
118	unregister_reboot_notifier(&wdt_notifier);
119	watchdog_unregister_device(&stmp3xxx_wdd);
120	return 0;
121}
122
123static int __maybe_unused stmp3xxx_wdt_suspend(struct device *dev)
124{
125	struct watchdog_device *wdd = &stmp3xxx_wdd;
126
127	if (watchdog_active(wdd))
128		return wdt_stop(wdd);
129
130	return 0;
131}
132
133static int __maybe_unused stmp3xxx_wdt_resume(struct device *dev)
134{
135	struct watchdog_device *wdd = &stmp3xxx_wdd;
136
137	if (watchdog_active(wdd))
138		return wdt_start(wdd);
139
140	return 0;
141}
142
143static SIMPLE_DEV_PM_OPS(stmp3xxx_wdt_pm_ops,
144			 stmp3xxx_wdt_suspend, stmp3xxx_wdt_resume);
145
146static struct platform_driver stmp3xxx_wdt_driver = {
147	.driver = {
148		.name = "stmp3xxx_rtc_wdt",
149		.pm = &stmp3xxx_wdt_pm_ops,
150	},
151	.probe = stmp3xxx_wdt_probe,
152	.remove = stmp3xxx_wdt_remove,
153};
154module_platform_driver(stmp3xxx_wdt_driver);
155
156MODULE_DESCRIPTION("STMP3XXX RTC Watchdog Driver");
157MODULE_LICENSE("GPL v2");
158MODULE_AUTHOR("Wolfram Sang <kernel@pengutronix.de>");