drivers/watchdog/shwdt.c - linux - Git at Google

 /*
  * drivers/watchdog/shwdt.c
  *
  * Watchdog driver for integrated watchdog in the SuperH processors.
  *
  * Copyright (C) 2001 - 2012  Paul Mundt <lethal@linux-sh.org>
  *
  * This program is free software; you can redistribute it and/or modify it
  * under the terms of the GNU General Public License as published by the
  * Free Software Foundation; either version 2 of the License, or (at your
  * option) any later version.
  *
  * 14-Dec-2001 Matt Domsch <Matt_Domsch@dell.com>
  *     Added nowayout module option to override CONFIG_WATCHDOG_NOWAYOUT
  *
  * 19-Apr-2002 Rob Radez <rob@osinvestor.com>
  *     Added expect close support, made emulated timeout runtime changeable
  *     general cleanups, add some ioctls
  */

 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

 #include <linux/module.h>
 #include <linux/moduleparam.h>
 #include <linux/platform_device.h>
 #include <linux/init.h>
 #include <linux/types.h>
 #include <linux/spinlock.h>
 #include <linux/watchdog.h>
 #include <linux/pm_runtime.h>
 #include <linux/fs.h>
 #include <linux/mm.h>
 #include <linux/slab.h>
 #include <linux/io.h>
 #include <linux/clk.h>
 #include <linux/err.h>
 #include <asm/watchdog.h>

 #define DRV_NAME "sh-wdt"

 /*
  * Default clock division ratio is 5.25 msecs. For an additional table of
  * values, consult the asm-sh/watchdog.h. Overload this at module load
  * time.
  *
  * In order for this to work reliably we need to have HZ set to 1000 or
  * something quite higher than 100 (or we need a proper high-res timer
  * implementation that will deal with this properly), otherwise the 10ms
  * resolution of a jiffy is enough to trigger the overflow. For things like
  * the SH-4 and SH-5, this isn't necessarily that big of a problem, though
  * for the SH-2 and SH-3, this isn't recommended unless the WDT is absolutely
  * necssary.
  *
  * As a result of this timing problem, the only modes that are particularly
  * feasible are the 4096 and the 2048 divisors, which yield 5.25 and 2.62ms
  * overflow periods respectively.
  *
  * Also, since we can't really expect userspace to be responsive enough
  * before the overflow happens, we maintain two separate timers .. One in
  * the kernel for clearing out WOVF every 2ms or so (again, this depends on
  * HZ == 1000), and another for monitoring userspace writes to the WDT device.
  *
  * As such, we currently use a configurable heartbeat interval which defaults
  * to 30s. In this case, the userspace daemon is only responsible for periodic
  * writes to the device before the next heartbeat is scheduled. If the daemon
  * misses its deadline, the kernel timer will allow the WDT to overflow.
  */
 static int clock_division_ratio = WTCSR_CKS_4096;
 #define next_ping_period(cks)	(jiffies + msecs_to_jiffies(cks - 4))

 #define WATCHDOG_HEARTBEAT 30			/* 30 sec default heartbeat */
 static int heartbeat = WATCHDOG_HEARTBEAT;	/* in seconds */
 static bool nowayout = WATCHDOG_NOWAYOUT;
 static unsigned long next_heartbeat;

 struct sh_wdt {
 	void __iomem		*base;
 	struct device		*dev;
 	struct clk		*clk;
 	spinlock_t		lock;

 	struct timer_list	timer;
 };

 static int sh_wdt_start(struct watchdog_device *wdt_dev)
 {
 	struct sh_wdt *wdt = watchdog_get_drvdata(wdt_dev);
 	unsigned long flags;
 	u8 csr;

 	pm_runtime_get_sync(wdt->dev);
 	clk_enable(wdt->clk);

 	spin_lock_irqsave(&wdt->lock, flags);

 	next_heartbeat = jiffies + (heartbeat * HZ);
 	mod_timer(&wdt->timer, next_ping_period(clock_division_ratio));

 	csr = sh_wdt_read_csr();
 	csr |= WTCSR_WT | clock_division_ratio;
 	sh_wdt_write_csr(csr);

 	sh_wdt_write_cnt(0);

 	/*
 	 * These processors have a bit of an inconsistent initialization
 	 * process.. starting with SH-3, RSTS was moved to WTCSR, and the
 	 * RSTCSR register was removed.
 	 *
 	 * On the SH-2 however, in addition with bits being in different
 	 * locations, we must deal with RSTCSR outright..
 	 */
 	csr = sh_wdt_read_csr();
 	csr |= WTCSR_TME;
 	csr &= ~WTCSR_RSTS;
 	sh_wdt_write_csr(csr);

 #ifdef CONFIG_CPU_SH2
 	csr = sh_wdt_read_rstcsr();
 	csr &= ~RSTCSR_RSTS;
 	sh_wdt_write_rstcsr(csr);
 #endif
 	spin_unlock_irqrestore(&wdt->lock, flags);

 	return 0;
 }

 static int sh_wdt_stop(struct watchdog_device *wdt_dev)
 {
 	struct sh_wdt *wdt = watchdog_get_drvdata(wdt_dev);
 	unsigned long flags;
 	u8 csr;

 	spin_lock_irqsave(&wdt->lock, flags);

 	del_timer(&wdt->timer);

 	csr = sh_wdt_read_csr();
 	csr &= ~WTCSR_TME;
 	sh_wdt_write_csr(csr);

 	spin_unlock_irqrestore(&wdt->lock, flags);

 	clk_disable(wdt->clk);
 	pm_runtime_put_sync(wdt->dev);

 	return 0;
 }

 static int sh_wdt_keepalive(struct watchdog_device *wdt_dev)
 {
 	struct sh_wdt *wdt = watchdog_get_drvdata(wdt_dev);
 	unsigned long flags;

 	spin_lock_irqsave(&wdt->lock, flags);
 	next_heartbeat = jiffies + (heartbeat * HZ);
 	spin_unlock_irqrestore(&wdt->lock, flags);

 	return 0;
 }

 static int sh_wdt_set_heartbeat(struct watchdog_device *wdt_dev, unsigned t)
 {
 	struct sh_wdt *wdt = watchdog_get_drvdata(wdt_dev);
 	unsigned long flags;

 	if (unlikely(t < 1 || t > 3600)) /* arbitrary upper limit */
 		return -EINVAL;

 	spin_lock_irqsave(&wdt->lock, flags);
 	heartbeat = t;
 	wdt_dev->timeout = t;
 	spin_unlock_irqrestore(&wdt->lock, flags);

 	return 0;
 }

 static void sh_wdt_ping(struct timer_list *t)
 {
 	struct sh_wdt *wdt = from_timer(wdt, t, timer);
 	unsigned long flags;

 	spin_lock_irqsave(&wdt->lock, flags);
 	if (time_before(jiffies, next_heartbeat)) {
 		u8 csr;

 		csr = sh_wdt_read_csr();
 		csr &= ~WTCSR_IOVF;
 		sh_wdt_write_csr(csr);

 		sh_wdt_write_cnt(0);

 		mod_timer(&wdt->timer, next_ping_period(clock_division_ratio));
 	} else
 		dev_warn(wdt->dev, "Heartbeat lost! Will not ping "
 		         "the watchdog\n");
 	spin_unlock_irqrestore(&wdt->lock, flags);
 }

 static const struct watchdog_info sh_wdt_info = {
 	.options		= WDIOF_KEEPALIVEPING | WDIOF_SETTIMEOUT |
 				  WDIOF_MAGICCLOSE,
 	.firmware_version	= 1,
 	.identity		= "SH WDT",
 };

 static const struct watchdog_ops sh_wdt_ops = {
 	.owner		= THIS_MODULE,
 	.start		= sh_wdt_start,
 	.stop		= sh_wdt_stop,
 	.ping		= sh_wdt_keepalive,
 	.set_timeout	= sh_wdt_set_heartbeat,
 };

 static struct watchdog_device sh_wdt_dev = {
 	.info	= &sh_wdt_info,
 	.ops	= &sh_wdt_ops,
 };

 static int sh_wdt_probe(struct platform_device *pdev)
 {
 	struct sh_wdt *wdt;
 	int rc;

 	/*
 	 * As this driver only covers the global watchdog case, reject
 	 * any attempts to register per-CPU watchdogs.
 	 */
 	if (pdev->id != -1)
 		return -EINVAL;

 	wdt = devm_kzalloc(&pdev->dev, sizeof(struct sh_wdt), GFP_KERNEL);
 	if (unlikely(!wdt))
 		return -ENOMEM;

 	wdt->dev = &pdev->dev;

 	wdt->clk = devm_clk_get(&pdev->dev, NULL);
 	if (IS_ERR(wdt->clk)) {
 		/*
 		 * Clock framework support is optional, continue on
 		 * anyways if we don't find a matching clock.
 		 */
 		wdt->clk = NULL;
 	}

 	wdt->base = devm_platform_ioremap_resource(pdev, 0);
 	if (IS_ERR(wdt->base))
 		return PTR_ERR(wdt->base);

 	watchdog_set_nowayout(&sh_wdt_dev, nowayout);
 	watchdog_set_drvdata(&sh_wdt_dev, wdt);
 	sh_wdt_dev.parent = &pdev->dev;

 	spin_lock_init(&wdt->lock);

 	rc = sh_wdt_set_heartbeat(&sh_wdt_dev, heartbeat);
 	if (unlikely(rc)) {
 		/* Default timeout if invalid */
 		sh_wdt_set_heartbeat(&sh_wdt_dev, WATCHDOG_HEARTBEAT);

 		dev_warn(&pdev->dev,
 			 "heartbeat value must be 1<=x<=3600, using %d\n",
 			 sh_wdt_dev.timeout);
 	}

 	dev_info(&pdev->dev, "configured with heartbeat=%d sec (nowayout=%d)\n",
 		 sh_wdt_dev.timeout, nowayout);

 	rc = watchdog_register_device(&sh_wdt_dev);
 	if (unlikely(rc)) {
 		dev_err(&pdev->dev, "Can't register watchdog (err=%d)\n", rc);
 		return rc;
 	}

 	timer_setup(&wdt->timer, sh_wdt_ping, 0);
 	wdt->timer.expires	= next_ping_period(clock_division_ratio);

 	dev_info(&pdev->dev, "initialized.\n");

 	pm_runtime_enable(&pdev->dev);

 	return 0;
 }

 static int sh_wdt_remove(struct platform_device *pdev)
 {
 	watchdog_unregister_device(&sh_wdt_dev);

 	pm_runtime_disable(&pdev->dev);

 	return 0;
 }

 static void sh_wdt_shutdown(struct platform_device *pdev)
 {
 	sh_wdt_stop(&sh_wdt_dev);
 }

 static struct platform_driver sh_wdt_driver = {
 	.driver		= {
 		.name	= DRV_NAME,
 	},

 	.probe		= sh_wdt_probe,
 	.remove		= sh_wdt_remove,
 	.shutdown	= sh_wdt_shutdown,
 };

 static int __init sh_wdt_init(void)
 {
 	if (unlikely(clock_division_ratio < 0x5 ||
 		     clock_division_ratio > 0x7)) {
 		clock_division_ratio = WTCSR_CKS_4096;

 		pr_info("divisor must be 0x5<=x<=0x7, using %d\n",
 			clock_division_ratio);
 	}

 	return platform_driver_register(&sh_wdt_driver);
 }

 static void __exit sh_wdt_exit(void)
 {
 	platform_driver_unregister(&sh_wdt_driver);
 }
 module_init(sh_wdt_init);
 module_exit(sh_wdt_exit);

 MODULE_AUTHOR("Paul Mundt <lethal@linux-sh.org>");
 MODULE_DESCRIPTION("SuperH watchdog driver");
 MODULE_LICENSE("GPL");
 MODULE_ALIAS("platform:" DRV_NAME);

 module_param(clock_division_ratio, int, 0);
 MODULE_PARM_DESC(clock_division_ratio,
 	"Clock division ratio. Valid ranges are from 0x5 (1.31ms) "
 	"to 0x7 (5.25ms). (default=" __MODULE_STRING(WTCSR_CKS_4096) ")");

 module_param(heartbeat, int, 0);
 MODULE_PARM_DESC(heartbeat,
 	"Watchdog heartbeat in seconds. (1 <= heartbeat <= 3600, default="
 				__MODULE_STRING(WATCHDOG_HEARTBEAT) ")");

 module_param(nowayout, bool, 0);
 MODULE_PARM_DESC(nowayout,
 	"Watchdog cannot be stopped once started (default="
 				__MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
	/*
	* drivers/watchdog/shwdt.c
	*
	* Watchdog driver for integrated watchdog in the SuperH processors.
	*
	* Copyright (C) 2001 - 2012 Paul Mundt <lethal@linux-sh.org>
	*
	* This program is free software; you can redistribute it and/or modify it
	* under the terms of the GNU General Public License as published by the
	* Free Software Foundation; either version 2 of the License, or (at your
	* option) any later version.
	*
	* 14-Dec-2001 Matt Domsch <Matt_Domsch@dell.com>
	* Added nowayout module option to override CONFIG_WATCHDOG_NOWAYOUT
	*
	* 19-Apr-2002 Rob Radez <rob@osinvestor.com>
	* Added expect close support, made emulated timeout runtime changeable
	* general cleanups, add some ioctls
	*/

	#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

	#include <linux/module.h>
	#include <linux/moduleparam.h>
	#include <linux/platform_device.h>
	#include <linux/init.h>
	#include <linux/types.h>
	#include <linux/spinlock.h>
	#include <linux/watchdog.h>
	#include <linux/pm_runtime.h>
	#include <linux/fs.h>
	#include <linux/mm.h>
	#include <linux/slab.h>
	#include <linux/io.h>
	#include <linux/clk.h>
	#include <linux/err.h>
	#include <asm/watchdog.h>

	#define DRV_NAME "sh-wdt"

	/*
	* Default clock division ratio is 5.25 msecs. For an additional table of
	* values, consult the asm-sh/watchdog.h. Overload this at module load
	* time.
	*
	* In order for this to work reliably we need to have HZ set to 1000 or
	* something quite higher than 100 (or we need a proper high-res timer
	* implementation that will deal with this properly), otherwise the 10ms
	* resolution of a jiffy is enough to trigger the overflow. For things like
	* the SH-4 and SH-5, this isn't necessarily that big of a problem, though
	* for the SH-2 and SH-3, this isn't recommended unless the WDT is absolutely
	* necssary.
	*
	* As a result of this timing problem, the only modes that are particularly
	* feasible are the 4096 and the 2048 divisors, which yield 5.25 and 2.62ms
	* overflow periods respectively.
	*
	* Also, since we can't really expect userspace to be responsive enough
	* before the overflow happens, we maintain two separate timers .. One in
	* the kernel for clearing out WOVF every 2ms or so (again, this depends on
	* HZ == 1000), and another for monitoring userspace writes to the WDT device.
	*
	* As such, we currently use a configurable heartbeat interval which defaults
	* to 30s. In this case, the userspace daemon is only responsible for periodic
	* writes to the device before the next heartbeat is scheduled. If the daemon
	* misses its deadline, the kernel timer will allow the WDT to overflow.
	*/
	static int clock_division_ratio = WTCSR_CKS_4096;
	#define next_ping_period(cks) (jiffies + msecs_to_jiffies(cks - 4))

	#define WATCHDOG_HEARTBEAT 30 /* 30 sec default heartbeat */
	static int heartbeat = WATCHDOG_HEARTBEAT; /* in seconds */
	static bool nowayout = WATCHDOG_NOWAYOUT;
	static unsigned long next_heartbeat;

	struct sh_wdt {
	void __iomem *base;
	struct device *dev;
	struct clk *clk;
	spinlock_t lock;

	struct timer_list timer;
	};

	static int sh_wdt_start(struct watchdog_device *wdt_dev)
	{
	struct sh_wdt *wdt = watchdog_get_drvdata(wdt_dev);
	unsigned long flags;
	u8 csr;

	pm_runtime_get_sync(wdt->dev);
	clk_enable(wdt->clk);

	spin_lock_irqsave(&wdt->lock, flags);

	next_heartbeat = jiffies + (heartbeat * HZ);
	mod_timer(&wdt->timer, next_ping_period(clock_division_ratio));

	csr = sh_wdt_read_csr();
	csr \|= WTCSR_WT \| clock_division_ratio;
	sh_wdt_write_csr(csr);

	sh_wdt_write_cnt(0);

	/*
	* These processors have a bit of an inconsistent initialization
	* process.. starting with SH-3, RSTS was moved to WTCSR, and the
	* RSTCSR register was removed.
	*
	* On the SH-2 however, in addition with bits being in different
	* locations, we must deal with RSTCSR outright..
	*/
	csr = sh_wdt_read_csr();
	csr \|= WTCSR_TME;
	csr &= ~WTCSR_RSTS;
	sh_wdt_write_csr(csr);

	#ifdef CONFIG_CPU_SH2
	csr = sh_wdt_read_rstcsr();
	csr &= ~RSTCSR_RSTS;
	sh_wdt_write_rstcsr(csr);
	#endif
	spin_unlock_irqrestore(&wdt->lock, flags);

	return 0;
	}

	static int sh_wdt_stop(struct watchdog_device *wdt_dev)
	{
	struct sh_wdt *wdt = watchdog_get_drvdata(wdt_dev);
	unsigned long flags;
	u8 csr;

	spin_lock_irqsave(&wdt->lock, flags);

	del_timer(&wdt->timer);

	csr = sh_wdt_read_csr();
	csr &= ~WTCSR_TME;
	sh_wdt_write_csr(csr);

	spin_unlock_irqrestore(&wdt->lock, flags);

	clk_disable(wdt->clk);
	pm_runtime_put_sync(wdt->dev);

	return 0;
	}

	static int sh_wdt_keepalive(struct watchdog_device *wdt_dev)
	{
	struct sh_wdt *wdt = watchdog_get_drvdata(wdt_dev);
	unsigned long flags;

	spin_lock_irqsave(&wdt->lock, flags);
	next_heartbeat = jiffies + (heartbeat * HZ);
	spin_unlock_irqrestore(&wdt->lock, flags);

	return 0;
	}

	static int sh_wdt_set_heartbeat(struct watchdog_device *wdt_dev, unsigned t)
	{
	struct sh_wdt *wdt = watchdog_get_drvdata(wdt_dev);
	unsigned long flags;

	if (unlikely(t < 1 \|\| t > 3600)) /* arbitrary upper limit */
	return -EINVAL;

	spin_lock_irqsave(&wdt->lock, flags);
	heartbeat = t;
	wdt_dev->timeout = t;
	spin_unlock_irqrestore(&wdt->lock, flags);

	return 0;
	}

	static void sh_wdt_ping(struct timer_list *t)
	{
	struct sh_wdt *wdt = from_timer(wdt, t, timer);
	unsigned long flags;

	spin_lock_irqsave(&wdt->lock, flags);
	if (time_before(jiffies, next_heartbeat)) {
	u8 csr;

	csr = sh_wdt_read_csr();
	csr &= ~WTCSR_IOVF;
	sh_wdt_write_csr(csr);

	sh_wdt_write_cnt(0);

	mod_timer(&wdt->timer, next_ping_period(clock_division_ratio));
	} else
	dev_warn(wdt->dev, "Heartbeat lost! Will not ping "
	"the watchdog\n");
	spin_unlock_irqrestore(&wdt->lock, flags);
	}

	static const struct watchdog_info sh_wdt_info = {
	.options = WDIOF_KEEPALIVEPING \| WDIOF_SETTIMEOUT \|
	WDIOF_MAGICCLOSE,
	.firmware_version = 1,
	.identity = "SH WDT",
	};

	static const struct watchdog_ops sh_wdt_ops = {
	.owner = THIS_MODULE,
	.start = sh_wdt_start,
	.stop = sh_wdt_stop,
	.ping = sh_wdt_keepalive,
	.set_timeout = sh_wdt_set_heartbeat,
	};

	static struct watchdog_device sh_wdt_dev = {
	.info = &sh_wdt_info,
	.ops = &sh_wdt_ops,
	};

	static int sh_wdt_probe(struct platform_device *pdev)
	{
	struct sh_wdt *wdt;
	int rc;

	/*
	* As this driver only covers the global watchdog case, reject
	* any attempts to register per-CPU watchdogs.
	*/
	if (pdev->id != -1)
	return -EINVAL;

	wdt = devm_kzalloc(&pdev->dev, sizeof(struct sh_wdt), GFP_KERNEL);
	if (unlikely(!wdt))
	return -ENOMEM;

	wdt->dev = &pdev->dev;

	wdt->clk = devm_clk_get(&pdev->dev, NULL);
	if (IS_ERR(wdt->clk)) {
	/*
	* Clock framework support is optional, continue on
	* anyways if we don't find a matching clock.
	*/
	wdt->clk = NULL;
	}

	wdt->base = devm_platform_ioremap_resource(pdev, 0);
	if (IS_ERR(wdt->base))
	return PTR_ERR(wdt->base);

	watchdog_set_nowayout(&sh_wdt_dev, nowayout);
	watchdog_set_drvdata(&sh_wdt_dev, wdt);
	sh_wdt_dev.parent = &pdev->dev;

	spin_lock_init(&wdt->lock);

	rc = sh_wdt_set_heartbeat(&sh_wdt_dev, heartbeat);
	if (unlikely(rc)) {
	/* Default timeout if invalid */
	sh_wdt_set_heartbeat(&sh_wdt_dev, WATCHDOG_HEARTBEAT);

	dev_warn(&pdev->dev,
	"heartbeat value must be 1<=x<=3600, using %d\n",
	sh_wdt_dev.timeout);
	}

	dev_info(&pdev->dev, "configured with heartbeat=%d sec (nowayout=%d)\n",
	sh_wdt_dev.timeout, nowayout);

	rc = watchdog_register_device(&sh_wdt_dev);
	if (unlikely(rc)) {
	dev_err(&pdev->dev, "Can't register watchdog (err=%d)\n", rc);
	return rc;
	}

	timer_setup(&wdt->timer, sh_wdt_ping, 0);
	wdt->timer.expires = next_ping_period(clock_division_ratio);

	dev_info(&pdev->dev, "initialized.\n");

	pm_runtime_enable(&pdev->dev);

	return 0;
	}

	static int sh_wdt_remove(struct platform_device *pdev)
	{
	watchdog_unregister_device(&sh_wdt_dev);

	pm_runtime_disable(&pdev->dev);

	return 0;
	}

	static void sh_wdt_shutdown(struct platform_device *pdev)
	{
	sh_wdt_stop(&sh_wdt_dev);
	}

	static struct platform_driver sh_wdt_driver = {
	.driver = {
	.name = DRV_NAME,
	},

	.probe = sh_wdt_probe,
	.remove = sh_wdt_remove,
	.shutdown = sh_wdt_shutdown,
	};

	static int __init sh_wdt_init(void)
	{
	if (unlikely(clock_division_ratio < 0x5 \|\|
	clock_division_ratio > 0x7)) {
	clock_division_ratio = WTCSR_CKS_4096;

	pr_info("divisor must be 0x5<=x<=0x7, using %d\n",
	clock_division_ratio);
	}

	return platform_driver_register(&sh_wdt_driver);
	}

	static void __exit sh_wdt_exit(void)
	{
	platform_driver_unregister(&sh_wdt_driver);
	}
	module_init(sh_wdt_init);
	module_exit(sh_wdt_exit);

	MODULE_AUTHOR("Paul Mundt <lethal@linux-sh.org>");
	MODULE_DESCRIPTION("SuperH watchdog driver");
	MODULE_LICENSE("GPL");
	MODULE_ALIAS("platform:" DRV_NAME);

	module_param(clock_division_ratio, int, 0);
	MODULE_PARM_DESC(clock_division_ratio,
	"Clock division ratio. Valid ranges are from 0x5 (1.31ms) "
	"to 0x7 (5.25ms). (default=" __MODULE_STRING(WTCSR_CKS_4096) ")");

	module_param(heartbeat, int, 0);
	MODULE_PARM_DESC(heartbeat,
	"Watchdog heartbeat in seconds. (1 <= heartbeat <= 3600, default="
	__MODULE_STRING(WATCHDOG_HEARTBEAT) ")");

	module_param(nowayout, bool, 0);
	MODULE_PARM_DESC(nowayout,
	"Watchdog cannot be stopped once started (default="
	__MODULE_STRING(WATCHDOG_NOWAYOUT) ")");