drivers/watchdog/at91sam9_wdt.c - linux - Git at Google

 // SPDX-License-Identifier: GPL-2.0+
 /*
  * Watchdog driver for Atmel AT91SAM9x processors.
  *
  * Copyright (C) 2008 Renaud CERRATO r.cerrato@til-technologies.fr
  *
  */

 /*
  * The Watchdog Timer Mode Register can be only written to once. If the
  * timeout need to be set from Linux, be sure that the bootstrap or the
  * bootloader doesn't write to this register.
  */

 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

 #include <linux/clk.h>
 #include <linux/errno.h>
 #include <linux/init.h>
 #include <linux/interrupt.h>
 #include <linux/io.h>
 #include <linux/kernel.h>
 #include <linux/module.h>
 #include <linux/moduleparam.h>
 #include <linux/platform_device.h>
 #include <linux/reboot.h>
 #include <linux/types.h>
 #include <linux/watchdog.h>
 #include <linux/jiffies.h>
 #include <linux/timer.h>
 #include <linux/bitops.h>
 #include <linux/uaccess.h>
 #include <linux/of.h>
 #include <linux/of_irq.h>

 #include "at91sam9_wdt.h"

 #define DRV_NAME "AT91SAM9 Watchdog"

 #define wdt_read(wdt, field) \
 	readl_relaxed((wdt)->base + (field))
 #define wdt_write(wtd, field, val) \
 	writel_relaxed((val), (wdt)->base + (field))

 /* AT91SAM9 watchdog runs a 12bit counter @ 256Hz,
  * use this to convert a watchdog
  * value from/to milliseconds.
  */
 #define ticks_to_hz_rounddown(t)	((((t) + 1) * HZ) >> 8)
 #define ticks_to_hz_roundup(t)		(((((t) + 1) * HZ) + 255) >> 8)
 #define ticks_to_secs(t)		(((t) + 1) >> 8)
 #define secs_to_ticks(s)		((s) ? (((s) << 8) - 1) : 0)

 #define WDT_MR_RESET	0x3FFF2FFF

 /* Watchdog max counter value in ticks */
 #define WDT_COUNTER_MAX_TICKS	0xFFF

 /* Watchdog max delta/value in secs */
 #define WDT_COUNTER_MAX_SECS	ticks_to_secs(WDT_COUNTER_MAX_TICKS)

 /* Hardware timeout in seconds */
 #define WDT_HW_TIMEOUT 2

 /* Timer heartbeat (500ms) */
 #define WDT_TIMEOUT	(HZ/2)

 /* User land timeout */
 #define WDT_HEARTBEAT 15
 static int heartbeat;
 module_param(heartbeat, int, 0);
 MODULE_PARM_DESC(heartbeat, "Watchdog heartbeats in seconds. "
 	"(default = " __MODULE_STRING(WDT_HEARTBEAT) ")");

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

 #define to_wdt(wdd) container_of(wdd, struct at91wdt, wdd)
 struct at91wdt {
 	struct watchdog_device wdd;
 	void __iomem *base;
 	unsigned long next_heartbeat;	/* the next_heartbeat for the timer */
 	struct timer_list timer;	/* The timer that pings the watchdog */
 	u32 mr;
 	u32 mr_mask;
 	unsigned long heartbeat;	/* WDT heartbeat in jiffies */
 	bool nowayout;
 	unsigned int irq;
 	struct clk *sclk;
 };

 /* ......................................................................... */

 static irqreturn_t wdt_interrupt(int irq, void *dev_id)
 {
 	struct at91wdt *wdt = (struct at91wdt *)dev_id;

 	if (wdt_read(wdt, AT91_WDT_SR)) {
 		pr_crit("at91sam9 WDT software reset\n");
 		emergency_restart();
 		pr_crit("Reboot didn't ?????\n");
 	}

 	return IRQ_HANDLED;
 }

 /*
  * Reload the watchdog timer.  (ie, pat the watchdog)
  */
 static inline void at91_wdt_reset(struct at91wdt *wdt)
 {
 	wdt_write(wdt, AT91_WDT_CR, AT91_WDT_KEY | AT91_WDT_WDRSTT);
 }

 /*
  * Timer tick
  */
 static void at91_ping(struct timer_list *t)
 {
 	struct at91wdt *wdt = from_timer(wdt, t, timer);
 	if (time_before(jiffies, wdt->next_heartbeat) ||
 	    !watchdog_active(&wdt->wdd)) {
 		at91_wdt_reset(wdt);
 		mod_timer(&wdt->timer, jiffies + wdt->heartbeat);
 	} else {
 		pr_crit("I will reset your machine !\n");
 	}
 }

 static int at91_wdt_start(struct watchdog_device *wdd)
 {
 	struct at91wdt *wdt = to_wdt(wdd);
 	/* calculate when the next userspace timeout will be */
 	wdt->next_heartbeat = jiffies + wdd->timeout * HZ;
 	return 0;
 }

 static int at91_wdt_stop(struct watchdog_device *wdd)
 {
 	/* The watchdog timer hardware can not be stopped... */
 	return 0;
 }

 static int at91_wdt_set_timeout(struct watchdog_device *wdd, unsigned int new_timeout)
 {
 	wdd->timeout = new_timeout;
 	return at91_wdt_start(wdd);
 }

 static int at91_wdt_init(struct platform_device *pdev, struct at91wdt *wdt)
 {
 	u32 tmp;
 	u32 delta;
 	u32 value;
 	int err;
 	u32 mask = wdt->mr_mask;
 	unsigned long min_heartbeat = 1;
 	unsigned long max_heartbeat;
 	struct device *dev = &pdev->dev;

 	tmp = wdt_read(wdt, AT91_WDT_MR);
 	if ((tmp & mask) != (wdt->mr & mask)) {
 		if (tmp == WDT_MR_RESET) {
 			wdt_write(wdt, AT91_WDT_MR, wdt->mr);
 			tmp = wdt_read(wdt, AT91_WDT_MR);
 		}
 	}

 	if (tmp & AT91_WDT_WDDIS) {
 		if (wdt->mr & AT91_WDT_WDDIS)
 			return 0;
 		dev_err(dev, "watchdog is disabled\n");
 		return -EINVAL;
 	}

 	value = tmp & AT91_WDT_WDV;
 	delta = (tmp & AT91_WDT_WDD) >> 16;

 	if (delta < value)
 		min_heartbeat = ticks_to_hz_roundup(value - delta);

 	max_heartbeat = ticks_to_hz_rounddown(value);
 	if (!max_heartbeat) {
 		dev_err(dev,
 			"heartbeat is too small for the system to handle it correctly\n");
 		return -EINVAL;
 	}

 	/*
 	 * Try to reset the watchdog counter 4 or 2 times more often than
 	 * actually requested, to avoid spurious watchdog reset.
 	 * If this is not possible because of the min_heartbeat value, reset
 	 * it at the min_heartbeat period.
 	 */
 	if ((max_heartbeat / 4) >= min_heartbeat)
 		wdt->heartbeat = max_heartbeat / 4;
 	else if ((max_heartbeat / 2) >= min_heartbeat)
 		wdt->heartbeat = max_heartbeat / 2;
 	else
 		wdt->heartbeat = min_heartbeat;

 	if (max_heartbeat < min_heartbeat + 4)
 		dev_warn(dev,
 			 "min heartbeat and max heartbeat might be too close for the system to handle it correctly\n");

 	if ((tmp & AT91_WDT_WDFIEN) && wdt->irq) {
 		err = request_irq(wdt->irq, wdt_interrupt,
 				  IRQF_SHARED | IRQF_IRQPOLL |
 				  IRQF_NO_SUSPEND,
 				  pdev->name, wdt);
 		if (err)
 			return err;
 	}

 	if ((tmp & wdt->mr_mask) != (wdt->mr & wdt->mr_mask))
 		dev_warn(dev,
 			 "watchdog already configured differently (mr = %x expecting %x)\n",
 			 tmp & wdt->mr_mask, wdt->mr & wdt->mr_mask);

 	timer_setup(&wdt->timer, at91_ping, 0);

 	/*
 	 * Use min_heartbeat the first time to avoid spurious watchdog reset:
 	 * we don't know for how long the watchdog counter is running, and
 	 *  - resetting it right now might trigger a watchdog fault reset
 	 *  - waiting for heartbeat time might lead to a watchdog timeout
 	 *    reset
 	 */
 	mod_timer(&wdt->timer, jiffies + min_heartbeat);

 	/* Try to set timeout from device tree first */
 	if (watchdog_init_timeout(&wdt->wdd, 0, dev))
 		watchdog_init_timeout(&wdt->wdd, heartbeat, dev);
 	watchdog_set_nowayout(&wdt->wdd, wdt->nowayout);
 	err = watchdog_register_device(&wdt->wdd);
 	if (err)
 		goto out_stop_timer;

 	wdt->next_heartbeat = jiffies + wdt->wdd.timeout * HZ;

 	return 0;

 out_stop_timer:
 	del_timer(&wdt->timer);
 	return err;
 }

 /* ......................................................................... */

 static const struct watchdog_info at91_wdt_info = {
 	.identity	= DRV_NAME,
 	.options	= WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING |
 						WDIOF_MAGICCLOSE,
 };

 static const struct watchdog_ops at91_wdt_ops = {
 	.owner =	THIS_MODULE,
 	.start =	at91_wdt_start,
 	.stop =		at91_wdt_stop,
 	.set_timeout =	at91_wdt_set_timeout,
 };

 #if defined(CONFIG_OF)
 static int of_at91wdt_init(struct device_node *np, struct at91wdt *wdt)
 {
 	u32 min = 0;
 	u32 max = WDT_COUNTER_MAX_SECS;
 	const char *tmp;

 	/* Get the interrupts property */
 	wdt->irq = irq_of_parse_and_map(np, 0);
 	if (!wdt->irq)
 		dev_warn(wdt->wdd.parent, "failed to get IRQ from DT\n");

 	if (!of_property_read_u32_index(np, "atmel,max-heartbeat-sec", 0,
 					&max)) {
 		if (!max || max > WDT_COUNTER_MAX_SECS)
 			max = WDT_COUNTER_MAX_SECS;

 		if (!of_property_read_u32_index(np, "atmel,min-heartbeat-sec",
 						0, &min)) {
 			if (min >= max)
 				min = max - 1;
 		}
 	}

 	min = secs_to_ticks(min);
 	max = secs_to_ticks(max);

 	wdt->mr_mask = 0x3FFFFFFF;
 	wdt->mr = 0;
 	if (!of_property_read_string(np, "atmel,watchdog-type", &tmp) &&
 	    !strcmp(tmp, "software")) {
 		wdt->mr |= AT91_WDT_WDFIEN;
 		wdt->mr_mask &= ~AT91_WDT_WDRPROC;
 	} else {
 		wdt->mr |= AT91_WDT_WDRSTEN;
 	}

 	if (!of_property_read_string(np, "atmel,reset-type", &tmp) &&
 	    !strcmp(tmp, "proc"))
 		wdt->mr |= AT91_WDT_WDRPROC;

 	if (of_property_read_bool(np, "atmel,disable")) {
 		wdt->mr |= AT91_WDT_WDDIS;
 		wdt->mr_mask &= AT91_WDT_WDDIS;
 	}

 	if (of_property_read_bool(np, "atmel,idle-halt"))
 		wdt->mr |= AT91_WDT_WDIDLEHLT;

 	if (of_property_read_bool(np, "atmel,dbg-halt"))
 		wdt->mr |= AT91_WDT_WDDBGHLT;

 	wdt->mr |= max | ((max - min) << 16);

 	return 0;
 }
 #else
 static inline int of_at91wdt_init(struct device_node *np, struct at91wdt *wdt)
 {
 	return 0;
 }
 #endif

 static int __init at91wdt_probe(struct platform_device *pdev)
 {
 	int err;
 	struct at91wdt *wdt;

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

 	wdt->mr = (WDT_HW_TIMEOUT * 256) | AT91_WDT_WDRSTEN | AT91_WDT_WDD |
 		  AT91_WDT_WDDBGHLT | AT91_WDT_WDIDLEHLT;
 	wdt->mr_mask = 0x3FFFFFFF;
 	wdt->nowayout = nowayout;
 	wdt->wdd.parent = &pdev->dev;
 	wdt->wdd.info = &at91_wdt_info;
 	wdt->wdd.ops = &at91_wdt_ops;
 	wdt->wdd.timeout = WDT_HEARTBEAT;
 	wdt->wdd.min_timeout = 1;
 	wdt->wdd.max_timeout = 0xFFFF;

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

 	wdt->sclk = devm_clk_get(&pdev->dev, NULL);
 	if (IS_ERR(wdt->sclk))
 		return PTR_ERR(wdt->sclk);

 	err = clk_prepare_enable(wdt->sclk);
 	if (err) {
 		dev_err(&pdev->dev, "Could not enable slow clock\n");
 		return err;
 	}

 	if (pdev->dev.of_node) {
 		err = of_at91wdt_init(pdev->dev.of_node, wdt);
 		if (err)
 			goto err_clk;
 	}

 	err = at91_wdt_init(pdev, wdt);
 	if (err)
 		goto err_clk;

 	platform_set_drvdata(pdev, wdt);

 	pr_info("enabled (heartbeat=%d sec, nowayout=%d)\n",
 		wdt->wdd.timeout, wdt->nowayout);

 	return 0;

 err_clk:
 	clk_disable_unprepare(wdt->sclk);

 	return err;
 }

 static int __exit at91wdt_remove(struct platform_device *pdev)
 {
 	struct at91wdt *wdt = platform_get_drvdata(pdev);
 	watchdog_unregister_device(&wdt->wdd);

 	pr_warn("I quit now, hardware will probably reboot!\n");
 	del_timer(&wdt->timer);
 	clk_disable_unprepare(wdt->sclk);

 	return 0;
 }

 #if defined(CONFIG_OF)
 static const struct of_device_id at91_wdt_dt_ids[] = {
 	{ .compatible = "atmel,at91sam9260-wdt" },
 	{ /* sentinel */ }
 };

 MODULE_DEVICE_TABLE(of, at91_wdt_dt_ids);
 #endif

 static struct platform_driver at91wdt_driver = {
 	.remove		= __exit_p(at91wdt_remove),
 	.driver		= {
 		.name	= "at91_wdt",
 		.of_match_table = of_match_ptr(at91_wdt_dt_ids),
 	},
 };

 module_platform_driver_probe(at91wdt_driver, at91wdt_probe);

 MODULE_AUTHOR("Renaud CERRATO <r.cerrato@til-technologies.fr>");
 MODULE_DESCRIPTION("Watchdog driver for Atmel AT91SAM9x processors");
 MODULE_LICENSE("GPL");
	// SPDX-License-Identifier: GPL-2.0+
	/*
	* Watchdog driver for Atmel AT91SAM9x processors.
	*
	* Copyright (C) 2008 Renaud CERRATO r.cerrato@til-technologies.fr
	*
	*/

	/*
	* The Watchdog Timer Mode Register can be only written to once. If the
	* timeout need to be set from Linux, be sure that the bootstrap or the
	* bootloader doesn't write to this register.
	*/

	#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

	#include <linux/clk.h>
	#include <linux/errno.h>
	#include <linux/init.h>
	#include <linux/interrupt.h>
	#include <linux/io.h>
	#include <linux/kernel.h>
	#include <linux/module.h>
	#include <linux/moduleparam.h>
	#include <linux/platform_device.h>
	#include <linux/reboot.h>
	#include <linux/types.h>
	#include <linux/watchdog.h>
	#include <linux/jiffies.h>
	#include <linux/timer.h>
	#include <linux/bitops.h>
	#include <linux/uaccess.h>
	#include <linux/of.h>
	#include <linux/of_irq.h>

	#include "at91sam9_wdt.h"

	#define DRV_NAME "AT91SAM9 Watchdog"

	#define wdt_read(wdt, field) \
	readl_relaxed((wdt)->base + (field))
	#define wdt_write(wtd, field, val) \
	writel_relaxed((val), (wdt)->base + (field))

	/* AT91SAM9 watchdog runs a 12bit counter @ 256Hz,
	* use this to convert a watchdog
	* value from/to milliseconds.
	*/
	#define ticks_to_hz_rounddown(t) ((((t) + 1) * HZ) >> 8)
	#define ticks_to_hz_roundup(t) (((((t) + 1) * HZ) + 255) >> 8)
	#define ticks_to_secs(t) (((t) + 1) >> 8)
	#define secs_to_ticks(s) ((s) ? (((s) << 8) - 1) : 0)

	#define WDT_MR_RESET 0x3FFF2FFF

	/* Watchdog max counter value in ticks */
	#define WDT_COUNTER_MAX_TICKS 0xFFF

	/* Watchdog max delta/value in secs */
	#define WDT_COUNTER_MAX_SECS ticks_to_secs(WDT_COUNTER_MAX_TICKS)

	/* Hardware timeout in seconds */
	#define WDT_HW_TIMEOUT 2

	/* Timer heartbeat (500ms) */
	#define WDT_TIMEOUT (HZ/2)

	/* User land timeout */
	#define WDT_HEARTBEAT 15
	static int heartbeat;
	module_param(heartbeat, int, 0);
	MODULE_PARM_DESC(heartbeat, "Watchdog heartbeats in seconds. "
	"(default = " __MODULE_STRING(WDT_HEARTBEAT) ")");

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

	#define to_wdt(wdd) container_of(wdd, struct at91wdt, wdd)
	struct at91wdt {
	struct watchdog_device wdd;
	void __iomem *base;
	unsigned long next_heartbeat; /* the next_heartbeat for the timer */
	struct timer_list timer; /* The timer that pings the watchdog */
	u32 mr;
	u32 mr_mask;
	unsigned long heartbeat; /* WDT heartbeat in jiffies */
	bool nowayout;
	unsigned int irq;
	struct clk *sclk;
	};

	/* ......................................................................... */

	static irqreturn_t wdt_interrupt(int irq, void *dev_id)
	{
	struct at91wdt wdt = (struct at91wdt )dev_id;

	if (wdt_read(wdt, AT91_WDT_SR)) {
	pr_crit("at91sam9 WDT software reset\n");
	emergency_restart();
	pr_crit("Reboot didn't ?????\n");
	}

	return IRQ_HANDLED;
	}

	/*
	* Reload the watchdog timer. (ie, pat the watchdog)
	*/
	static inline void at91_wdt_reset(struct at91wdt *wdt)
	{
	wdt_write(wdt, AT91_WDT_CR, AT91_WDT_KEY \| AT91_WDT_WDRSTT);
	}

	/*
	* Timer tick
	*/
	static void at91_ping(struct timer_list *t)
	{
	struct at91wdt *wdt = from_timer(wdt, t, timer);
	if (time_before(jiffies, wdt->next_heartbeat) \|\|
	!watchdog_active(&wdt->wdd)) {
	at91_wdt_reset(wdt);
	mod_timer(&wdt->timer, jiffies + wdt->heartbeat);
	} else {
	pr_crit("I will reset your machine !\n");
	}
	}

	static int at91_wdt_start(struct watchdog_device *wdd)
	{
	struct at91wdt *wdt = to_wdt(wdd);
	/* calculate when the next userspace timeout will be */
	wdt->next_heartbeat = jiffies + wdd->timeout * HZ;
	return 0;
	}

	static int at91_wdt_stop(struct watchdog_device *wdd)
	{
	/* The watchdog timer hardware can not be stopped... */
	return 0;
	}

	static int at91_wdt_set_timeout(struct watchdog_device *wdd, unsigned int new_timeout)
	{
	wdd->timeout = new_timeout;
	return at91_wdt_start(wdd);
	}

	static int at91_wdt_init(struct platform_device pdev, struct at91wdt wdt)
	{
	u32 tmp;
	u32 delta;
	u32 value;
	int err;
	u32 mask = wdt->mr_mask;
	unsigned long min_heartbeat = 1;
	unsigned long max_heartbeat;
	struct device *dev = &pdev->dev;

	tmp = wdt_read(wdt, AT91_WDT_MR);
	if ((tmp & mask) != (wdt->mr & mask)) {
	if (tmp == WDT_MR_RESET) {
	wdt_write(wdt, AT91_WDT_MR, wdt->mr);
	tmp = wdt_read(wdt, AT91_WDT_MR);
	}
	}

	if (tmp & AT91_WDT_WDDIS) {
	if (wdt->mr & AT91_WDT_WDDIS)
	return 0;
	dev_err(dev, "watchdog is disabled\n");
	return -EINVAL;
	}

	value = tmp & AT91_WDT_WDV;
	delta = (tmp & AT91_WDT_WDD) >> 16;

	if (delta < value)
	min_heartbeat = ticks_to_hz_roundup(value - delta);

	max_heartbeat = ticks_to_hz_rounddown(value);
	if (!max_heartbeat) {
	dev_err(dev,
	"heartbeat is too small for the system to handle it correctly\n");
	return -EINVAL;
	}

	/*
	* Try to reset the watchdog counter 4 or 2 times more often than
	* actually requested, to avoid spurious watchdog reset.
	* If this is not possible because of the min_heartbeat value, reset
	* it at the min_heartbeat period.
	*/
	if ((max_heartbeat / 4) >= min_heartbeat)
	wdt->heartbeat = max_heartbeat / 4;
	else if ((max_heartbeat / 2) >= min_heartbeat)
	wdt->heartbeat = max_heartbeat / 2;
	else
	wdt->heartbeat = min_heartbeat;

	if (max_heartbeat < min_heartbeat + 4)
	dev_warn(dev,
	"min heartbeat and max heartbeat might be too close for the system to handle it correctly\n");

	if ((tmp & AT91_WDT_WDFIEN) && wdt->irq) {
	err = request_irq(wdt->irq, wdt_interrupt,
	IRQF_SHARED \| IRQF_IRQPOLL \|
	IRQF_NO_SUSPEND,
	pdev->name, wdt);
	if (err)
	return err;
	}

	if ((tmp & wdt->mr_mask) != (wdt->mr & wdt->mr_mask))
	dev_warn(dev,
	"watchdog already configured differently (mr = %x expecting %x)\n",
	tmp & wdt->mr_mask, wdt->mr & wdt->mr_mask);

	timer_setup(&wdt->timer, at91_ping, 0);

	/*
	* Use min_heartbeat the first time to avoid spurious watchdog reset:
	* we don't know for how long the watchdog counter is running, and
	* - resetting it right now might trigger a watchdog fault reset
	* - waiting for heartbeat time might lead to a watchdog timeout
	* reset
	*/
	mod_timer(&wdt->timer, jiffies + min_heartbeat);

	/* Try to set timeout from device tree first */
	if (watchdog_init_timeout(&wdt->wdd, 0, dev))
	watchdog_init_timeout(&wdt->wdd, heartbeat, dev);
	watchdog_set_nowayout(&wdt->wdd, wdt->nowayout);
	err = watchdog_register_device(&wdt->wdd);
	if (err)
	goto out_stop_timer;

	wdt->next_heartbeat = jiffies + wdt->wdd.timeout * HZ;

	return 0;

	out_stop_timer:
	del_timer(&wdt->timer);
	return err;
	}

	/* ......................................................................... */

	static const struct watchdog_info at91_wdt_info = {
	.identity = DRV_NAME,
	.options = WDIOF_SETTIMEOUT \| WDIOF_KEEPALIVEPING \|
	WDIOF_MAGICCLOSE,
	};

	static const struct watchdog_ops at91_wdt_ops = {
	.owner = THIS_MODULE,
	.start = at91_wdt_start,
	.stop = at91_wdt_stop,
	.set_timeout = at91_wdt_set_timeout,
	};

	#if defined(CONFIG_OF)
	static int of_at91wdt_init(struct device_node np, struct at91wdt wdt)
	{
	u32 min = 0;
	u32 max = WDT_COUNTER_MAX_SECS;
	const char *tmp;

	/* Get the interrupts property */
	wdt->irq = irq_of_parse_and_map(np, 0);
	if (!wdt->irq)
	dev_warn(wdt->wdd.parent, "failed to get IRQ from DT\n");

	if (!of_property_read_u32_index(np, "atmel,max-heartbeat-sec", 0,
	&max)) {
	if (!max \|\| max > WDT_COUNTER_MAX_SECS)
	max = WDT_COUNTER_MAX_SECS;

	if (!of_property_read_u32_index(np, "atmel,min-heartbeat-sec",
	0, &min)) {
	if (min >= max)
	min = max - 1;
	}
	}

	min = secs_to_ticks(min);
	max = secs_to_ticks(max);

	wdt->mr_mask = 0x3FFFFFFF;
	wdt->mr = 0;
	if (!of_property_read_string(np, "atmel,watchdog-type", &tmp) &&
	!strcmp(tmp, "software")) {
	wdt->mr \|= AT91_WDT_WDFIEN;
	wdt->mr_mask &= ~AT91_WDT_WDRPROC;
	} else {
	wdt->mr \|= AT91_WDT_WDRSTEN;
	}

	if (!of_property_read_string(np, "atmel,reset-type", &tmp) &&
	!strcmp(tmp, "proc"))
	wdt->mr \|= AT91_WDT_WDRPROC;

	if (of_property_read_bool(np, "atmel,disable")) {
	wdt->mr \|= AT91_WDT_WDDIS;
	wdt->mr_mask &= AT91_WDT_WDDIS;
	}

	if (of_property_read_bool(np, "atmel,idle-halt"))
	wdt->mr \|= AT91_WDT_WDIDLEHLT;

	if (of_property_read_bool(np, "atmel,dbg-halt"))
	wdt->mr \|= AT91_WDT_WDDBGHLT;

	wdt->mr \|= max \| ((max - min) << 16);

	return 0;
	}
	#else
	static inline int of_at91wdt_init(struct device_node np, struct at91wdt wdt)
	{
	return 0;
	}
	#endif

	static int __init at91wdt_probe(struct platform_device *pdev)
	{
	int err;
	struct at91wdt *wdt;

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

	wdt->mr = (WDT_HW_TIMEOUT * 256) \| AT91_WDT_WDRSTEN \| AT91_WDT_WDD \|
	AT91_WDT_WDDBGHLT \| AT91_WDT_WDIDLEHLT;
	wdt->mr_mask = 0x3FFFFFFF;
	wdt->nowayout = nowayout;
	wdt->wdd.parent = &pdev->dev;
	wdt->wdd.info = &at91_wdt_info;
	wdt->wdd.ops = &at91_wdt_ops;
	wdt->wdd.timeout = WDT_HEARTBEAT;
	wdt->wdd.min_timeout = 1;
	wdt->wdd.max_timeout = 0xFFFF;

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

	wdt->sclk = devm_clk_get(&pdev->dev, NULL);
	if (IS_ERR(wdt->sclk))
	return PTR_ERR(wdt->sclk);

	err = clk_prepare_enable(wdt->sclk);
	if (err) {
	dev_err(&pdev->dev, "Could not enable slow clock\n");
	return err;
	}

	if (pdev->dev.of_node) {
	err = of_at91wdt_init(pdev->dev.of_node, wdt);
	if (err)
	goto err_clk;
	}

	err = at91_wdt_init(pdev, wdt);
	if (err)
	goto err_clk;

	platform_set_drvdata(pdev, wdt);

	pr_info("enabled (heartbeat=%d sec, nowayout=%d)\n",
	wdt->wdd.timeout, wdt->nowayout);

	return 0;

	err_clk:
	clk_disable_unprepare(wdt->sclk);

	return err;
	}

	static int __exit at91wdt_remove(struct platform_device *pdev)
	{
	struct at91wdt *wdt = platform_get_drvdata(pdev);
	watchdog_unregister_device(&wdt->wdd);

	pr_warn("I quit now, hardware will probably reboot!\n");
	del_timer(&wdt->timer);
	clk_disable_unprepare(wdt->sclk);

	return 0;
	}

	#if defined(CONFIG_OF)
	static const struct of_device_id at91_wdt_dt_ids[] = {
	{ .compatible = "atmel,at91sam9260-wdt" },
	{ /* sentinel */ }
	};

	MODULE_DEVICE_TABLE(of, at91_wdt_dt_ids);
	#endif

	static struct platform_driver at91wdt_driver = {
	.remove = __exit_p(at91wdt_remove),
	.driver = {
	.name = "at91_wdt",
	.of_match_table = of_match_ptr(at91_wdt_dt_ids),
	},
	};

	module_platform_driver_probe(at91wdt_driver, at91wdt_probe);

	MODULE_AUTHOR("Renaud CERRATO <r.cerrato@til-technologies.fr>");
	MODULE_DESCRIPTION("Watchdog driver for Atmel AT91SAM9x processors");
	MODULE_LICENSE("GPL");