drivers/watchdog/coh901327_wdt.c - third_party/linux - Git at Google

 // SPDX-License-Identifier: GPL-2.0
 /*
  * coh901327_wdt.c
  *
  * Copyright (C) 2008-2009 ST-Ericsson AB
  * Watchdog driver for the ST-Ericsson AB COH 901 327 IP core
  * Author: Linus Walleij <linus.walleij@stericsson.com>
  */
 #include <linux/module.h>
 #include <linux/types.h>
 #include <linux/watchdog.h>
 #include <linux/interrupt.h>
 #include <linux/pm.h>
 #include <linux/platform_device.h>
 #include <linux/io.h>
 #include <linux/bitops.h>
 #include <linux/clk.h>
 #include <linux/delay.h>
 #include <linux/err.h>

 #define DRV_NAME "WDOG COH 901 327"

 /*
  * COH 901 327 register definitions
  */

 /* WDOG_FEED Register 32bit (-/W) */
 #define U300_WDOG_FR							0x00
 #define U300_WDOG_FR_FEED_RESTART_TIMER					0xFEEDU
 /* WDOG_TIMEOUT Register 32bit (R/W) */
 #define U300_WDOG_TR							0x04
 #define U300_WDOG_TR_TIMEOUT_MASK					0x7FFFU
 /* WDOG_DISABLE1 Register 32bit (-/W) */
 #define U300_WDOG_D1R							0x08
 #define U300_WDOG_D1R_DISABLE1_DISABLE_TIMER				0x2BADU
 /* WDOG_DISABLE2 Register 32bit (R/W) */
 #define U300_WDOG_D2R							0x0C
 #define U300_WDOG_D2R_DISABLE2_DISABLE_TIMER				0xCAFEU
 #define U300_WDOG_D2R_DISABLE_STATUS_DISABLED				0xDABEU
 #define U300_WDOG_D2R_DISABLE_STATUS_ENABLED				0x0000U
 /* WDOG_STATUS Register 32bit (R/W) */
 #define U300_WDOG_SR							0x10
 #define U300_WDOG_SR_STATUS_TIMED_OUT					0xCFE8U
 #define U300_WDOG_SR_STATUS_NORMAL					0x0000U
 #define U300_WDOG_SR_RESET_STATUS_RESET					0xE8B4U
 /* WDOG_COUNT Register 32bit (R/-) */
 #define U300_WDOG_CR							0x14
 #define U300_WDOG_CR_VALID_IND						0x8000U
 #define U300_WDOG_CR_VALID_STABLE					0x0000U
 #define U300_WDOG_CR_COUNT_VALUE_MASK					0x7FFFU
 /* WDOG_JTAGOVR Register 32bit (R/W) */
 #define U300_WDOG_JOR							0x18
 #define U300_WDOG_JOR_JTAG_MODE_IND					0x0002U
 #define U300_WDOG_JOR_JTAG_WATCHDOG_ENABLE				0x0001U
 /* WDOG_RESTART Register 32bit (-/W) */
 #define U300_WDOG_RR							0x1C
 #define U300_WDOG_RR_RESTART_VALUE_RESUME				0xACEDU
 /* WDOG_IRQ_EVENT Register 32bit (R/W) */
 #define U300_WDOG_IER							0x20
 #define U300_WDOG_IER_WILL_BARK_IRQ_EVENT_IND				0x0001U
 #define U300_WDOG_IER_WILL_BARK_IRQ_ACK_ENABLE				0x0001U
 /* WDOG_IRQ_MASK Register 32bit (R/W) */
 #define U300_WDOG_IMR							0x24
 #define U300_WDOG_IMR_WILL_BARK_IRQ_ENABLE				0x0001U
 /* WDOG_IRQ_FORCE Register 32bit (R/W) */
 #define U300_WDOG_IFR							0x28
 #define U300_WDOG_IFR_WILL_BARK_IRQ_FORCE_ENABLE			0x0001U

 /* Default timeout in seconds = 1 minute */
 #define U300_WDOG_DEFAULT_TIMEOUT					60

 static unsigned int margin;
 static int irq;
 static void __iomem *virtbase;
 static struct device *parent;

 static struct clk *clk;

 /*
  * Enabling and disabling functions.
  */
 static void coh901327_enable(u16 timeout)
 {
 	u16 val;
 	unsigned long freq;
 	unsigned long delay_ns;

 	/* Restart timer if it is disabled */
 	val = readw(virtbase + U300_WDOG_D2R);
 	if (val == U300_WDOG_D2R_DISABLE_STATUS_DISABLED)
 		writew(U300_WDOG_RR_RESTART_VALUE_RESUME,
 		       virtbase + U300_WDOG_RR);
 	/* Acknowledge any pending interrupt so it doesn't just fire off */
 	writew(U300_WDOG_IER_WILL_BARK_IRQ_ACK_ENABLE,
 	       virtbase + U300_WDOG_IER);
 	/*
 	 * The interrupt is cleared in the 32 kHz clock domain.
 	 * Wait 3 32 kHz cycles for it to take effect
 	 */
 	freq = clk_get_rate(clk);
 	delay_ns = DIV_ROUND_UP(1000000000, freq); /* Freq to ns and round up */
 	delay_ns = 3 * delay_ns; /* Wait 3 cycles */
 	ndelay(delay_ns);
 	/* Enable the watchdog interrupt */
 	writew(U300_WDOG_IMR_WILL_BARK_IRQ_ENABLE, virtbase + U300_WDOG_IMR);
 	/* Activate the watchdog timer */
 	writew(timeout, virtbase + U300_WDOG_TR);
 	/* Start the watchdog timer */
 	writew(U300_WDOG_FR_FEED_RESTART_TIMER, virtbase + U300_WDOG_FR);
 	/*
 	 * Extra read so that this change propagate in the watchdog.
 	 */
 	(void) readw(virtbase + U300_WDOG_CR);
 	val = readw(virtbase + U300_WDOG_D2R);
 	if (val != U300_WDOG_D2R_DISABLE_STATUS_ENABLED)
 		dev_err(parent,
 			"%s(): watchdog not enabled! D2R value %04x\n",
 			__func__, val);
 }

 static void coh901327_disable(void)
 {
 	u16 val;

 	/* Disable the watchdog interrupt if it is active */
 	writew(0x0000U, virtbase + U300_WDOG_IMR);
 	/* If the watchdog is currently enabled, attempt to disable it */
 	val = readw(virtbase + U300_WDOG_D2R);
 	if (val != U300_WDOG_D2R_DISABLE_STATUS_DISABLED) {
 		writew(U300_WDOG_D1R_DISABLE1_DISABLE_TIMER,
 		       virtbase + U300_WDOG_D1R);
 		writew(U300_WDOG_D2R_DISABLE2_DISABLE_TIMER,
 		       virtbase + U300_WDOG_D2R);
 		/* Write this twice (else problems occur) */
 		writew(U300_WDOG_D2R_DISABLE2_DISABLE_TIMER,
 		       virtbase + U300_WDOG_D2R);
 	}
 	val = readw(virtbase + U300_WDOG_D2R);
 	if (val != U300_WDOG_D2R_DISABLE_STATUS_DISABLED)
 		dev_err(parent,
 			"%s(): watchdog not disabled! D2R value %04x\n",
 			__func__, val);
 }

 static int coh901327_start(struct watchdog_device *wdt_dev)
 {
 	coh901327_enable(wdt_dev->timeout * 100);
 	return 0;
 }

 static int coh901327_stop(struct watchdog_device *wdt_dev)
 {
 	coh901327_disable();
 	return 0;
 }

 static int coh901327_ping(struct watchdog_device *wdd)
 {
 	/* Feed the watchdog */
 	writew(U300_WDOG_FR_FEED_RESTART_TIMER,
 	       virtbase + U300_WDOG_FR);
 	return 0;
 }

 static int coh901327_settimeout(struct watchdog_device *wdt_dev,
 				unsigned int time)
 {
 	wdt_dev->timeout = time;
 	/* Set new timeout value */
 	writew(time * 100, virtbase + U300_WDOG_TR);
 	/* Feed the dog */
 	writew(U300_WDOG_FR_FEED_RESTART_TIMER,
 	       virtbase + U300_WDOG_FR);
 	return 0;
 }

 static unsigned int coh901327_gettimeleft(struct watchdog_device *wdt_dev)
 {
 	u16 val;

 	/* Read repeatedly until the value is stable! */
 	val = readw(virtbase + U300_WDOG_CR);
 	while (val & U300_WDOG_CR_VALID_IND)
 		val = readw(virtbase + U300_WDOG_CR);
 	val &= U300_WDOG_CR_COUNT_VALUE_MASK;
 	if (val != 0)
 		val /= 100;

 	return val;
 }

 /*
  * This interrupt occurs 10 ms before the watchdog WILL bark.
  */
 static irqreturn_t coh901327_interrupt(int irq, void *data)
 {
 	u16 val;

 	/*
 	 * Ack IRQ? If this occurs we're FUBAR anyway, so
 	 * just acknowledge, disable the interrupt and await the imminent end.
 	 * If you at some point need a host of callbacks to be called
 	 * when the system is about to watchdog-reset, add them here!
 	 *
 	 * NOTE: on future versions of this IP-block, it will be possible
 	 * to prevent a watchdog reset by feeding the watchdog at this
 	 * point.
 	 */
 	val = readw(virtbase + U300_WDOG_IER);
 	if (val == U300_WDOG_IER_WILL_BARK_IRQ_EVENT_IND)
 		writew(U300_WDOG_IER_WILL_BARK_IRQ_ACK_ENABLE,
 		       virtbase + U300_WDOG_IER);
 	writew(0x0000U, virtbase + U300_WDOG_IMR);
 	dev_crit(parent, "watchdog is barking!\n");
 	return IRQ_HANDLED;
 }

 static const struct watchdog_info coh901327_ident = {
 	.options = WDIOF_CARDRESET | WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING,
 	.identity = DRV_NAME,
 };

 static const struct watchdog_ops coh901327_ops = {
 	.owner = THIS_MODULE,
 	.start = coh901327_start,
 	.stop = coh901327_stop,
 	.ping = coh901327_ping,
 	.set_timeout = coh901327_settimeout,
 	.get_timeleft = coh901327_gettimeleft,
 };

 static struct watchdog_device coh901327_wdt = {
 	.info = &coh901327_ident,
 	.ops = &coh901327_ops,
 	/*
 	 * Max timeout is 327 since the 10ms
 	 * timeout register is max
 	 * 0x7FFF = 327670ms ~= 327s.
 	 */
 	.min_timeout = 1,
 	.max_timeout = 327,
 	.timeout = U300_WDOG_DEFAULT_TIMEOUT,
 };

 static int __exit coh901327_remove(struct platform_device *pdev)
 {
 	watchdog_unregister_device(&coh901327_wdt);
 	coh901327_disable();
 	free_irq(irq, pdev);
 	clk_disable_unprepare(clk);
 	clk_put(clk);
 	return 0;
 }

 static int __init coh901327_probe(struct platform_device *pdev)
 {
 	struct device *dev = &pdev->dev;
 	int ret;
 	u16 val;
 	struct resource *res;

 	parent = dev;

 	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 	virtbase = devm_ioremap_resource(dev, res);
 	if (IS_ERR(virtbase))
 		return PTR_ERR(virtbase);

 	clk = clk_get(dev, NULL);
 	if (IS_ERR(clk)) {
 		ret = PTR_ERR(clk);
 		dev_err(dev, "could not get clock\n");
 		return ret;
 	}
 	ret = clk_prepare_enable(clk);
 	if (ret) {
 		dev_err(dev, "could not prepare and enable clock\n");
 		goto out_no_clk_enable;
 	}

 	val = readw(virtbase + U300_WDOG_SR);
 	switch (val) {
 	case U300_WDOG_SR_STATUS_TIMED_OUT:
 		dev_info(dev, "watchdog timed out since last chip reset!\n");
 		coh901327_wdt.bootstatus |= WDIOF_CARDRESET;
 		/* Status will be cleared below */
 		break;
 	case U300_WDOG_SR_STATUS_NORMAL:
 		dev_info(dev, "in normal status, no timeouts have occurred.\n");
 		break;
 	default:
 		dev_info(dev, "contains an illegal status code (%08x)\n", val);
 		break;
 	}

 	val = readw(virtbase + U300_WDOG_D2R);
 	switch (val) {
 	case U300_WDOG_D2R_DISABLE_STATUS_DISABLED:
 		dev_info(dev, "currently disabled.\n");
 		break;
 	case U300_WDOG_D2R_DISABLE_STATUS_ENABLED:
 		dev_info(dev, "currently enabled! (disabling it now)\n");
 		coh901327_disable();
 		break;
 	default:
 		dev_err(dev, "contains an illegal enable/disable code (%08x)\n",
 			val);
 		break;
 	}

 	/* Reset the watchdog */
 	writew(U300_WDOG_SR_RESET_STATUS_RESET, virtbase + U300_WDOG_SR);

 	irq = platform_get_irq(pdev, 0);
 	if (request_irq(irq, coh901327_interrupt, 0,
 			DRV_NAME " Bark", pdev)) {
 		ret = -EIO;
 		goto out_no_irq;
 	}

 	watchdog_init_timeout(&coh901327_wdt, margin, dev);

 	coh901327_wdt.parent = dev;
 	ret = watchdog_register_device(&coh901327_wdt);
 	if (ret)
 		goto out_no_wdog;

 	dev_info(dev, "initialized. (timeout=%d sec)\n",
 			coh901327_wdt.timeout);
 	return 0;

 out_no_wdog:
 	free_irq(irq, pdev);
 out_no_irq:
 	clk_disable_unprepare(clk);
 out_no_clk_enable:
 	clk_put(clk);
 	return ret;
 }

 #ifdef CONFIG_PM

 static u16 wdogenablestore;
 static u16 irqmaskstore;

 static int coh901327_suspend(struct platform_device *pdev, pm_message_t state)
 {
 	irqmaskstore = readw(virtbase + U300_WDOG_IMR) & 0x0001U;
 	wdogenablestore = readw(virtbase + U300_WDOG_D2R);
 	/* If watchdog is on, disable it here and now */
 	if (wdogenablestore == U300_WDOG_D2R_DISABLE_STATUS_ENABLED)
 		coh901327_disable();
 	return 0;
 }

 static int coh901327_resume(struct platform_device *pdev)
 {
 	/* Restore the watchdog interrupt */
 	writew(irqmaskstore, virtbase + U300_WDOG_IMR);
 	if (wdogenablestore == U300_WDOG_D2R_DISABLE_STATUS_ENABLED) {
 		/* Restart the watchdog timer */
 		writew(U300_WDOG_RR_RESTART_VALUE_RESUME,
 		       virtbase + U300_WDOG_RR);
 		writew(U300_WDOG_FR_FEED_RESTART_TIMER,
 		       virtbase + U300_WDOG_FR);
 	}
 	return 0;
 }
 #else
 #define coh901327_suspend NULL
 #define coh901327_resume  NULL
 #endif

 /*
  * Mistreating the watchdog is the only way to perform a software reset of the
  * system on EMP platforms. So we implement this and export a symbol for it.
  */
 void coh901327_watchdog_reset(void)
 {
 	/* Enable even if on JTAG too */
 	writew(U300_WDOG_JOR_JTAG_WATCHDOG_ENABLE,
 	       virtbase + U300_WDOG_JOR);
 	/*
 	 * Timeout = 5s, we have to wait for the watchdog reset to
 	 * actually take place: the watchdog will be reloaded with the
 	 * default value immediately, so we HAVE to reboot and get back
 	 * into the kernel in 30s, or the device will reboot again!
 	 * The boot loader will typically deactivate the watchdog, so we
 	 * need time enough for the boot loader to get to the point of
 	 * deactivating the watchdog before it is shut down by it.
 	 *
 	 * NOTE: on future versions of the watchdog, this restriction is
 	 * gone: the watchdog will be reloaded with a default value (1 min)
 	 * instead of last value, and you can conveniently set the watchdog
 	 * timeout to 10ms (value = 1) without any problems.
 	 */
 	coh901327_enable(500);
 	/* Return and await doom */
 }

 static const struct of_device_id coh901327_dt_match[] = {
 	{ .compatible = "stericsson,coh901327" },
 	{},
 };

 static struct platform_driver coh901327_driver = {
 	.driver = {
 		.name	= "coh901327_wdog",
 		.of_match_table = coh901327_dt_match,
 	},
 	.remove		= __exit_p(coh901327_remove),
 	.suspend	= coh901327_suspend,
 	.resume		= coh901327_resume,
 };

 module_platform_driver_probe(coh901327_driver, coh901327_probe);

 MODULE_AUTHOR("Linus Walleij <linus.walleij@stericsson.com>");
 MODULE_DESCRIPTION("COH 901 327 Watchdog");

 module_param(margin, uint, 0);
 MODULE_PARM_DESC(margin, "Watchdog margin in seconds (default 60s)");

 MODULE_LICENSE("GPL v2");
 MODULE_ALIAS("platform:coh901327-watchdog");
	// SPDX-License-Identifier: GPL-2.0
	/*
	* coh901327_wdt.c
	*
	* Copyright (C) 2008-2009 ST-Ericsson AB
	* Watchdog driver for the ST-Ericsson AB COH 901 327 IP core
	* Author: Linus Walleij <linus.walleij@stericsson.com>
	*/
	#include <linux/module.h>
	#include <linux/types.h>
	#include <linux/watchdog.h>
	#include <linux/interrupt.h>
	#include <linux/pm.h>
	#include <linux/platform_device.h>
	#include <linux/io.h>
	#include <linux/bitops.h>
	#include <linux/clk.h>
	#include <linux/delay.h>
	#include <linux/err.h>

	#define DRV_NAME "WDOG COH 901 327"

	/*
	* COH 901 327 register definitions
	*/

	/* WDOG_FEED Register 32bit (-/W) */
	#define U300_WDOG_FR 0x00
	#define U300_WDOG_FR_FEED_RESTART_TIMER 0xFEEDU
	/* WDOG_TIMEOUT Register 32bit (R/W) */
	#define U300_WDOG_TR 0x04
	#define U300_WDOG_TR_TIMEOUT_MASK 0x7FFFU
	/* WDOG_DISABLE1 Register 32bit (-/W) */
	#define U300_WDOG_D1R 0x08
	#define U300_WDOG_D1R_DISABLE1_DISABLE_TIMER 0x2BADU
	/* WDOG_DISABLE2 Register 32bit (R/W) */
	#define U300_WDOG_D2R 0x0C
	#define U300_WDOG_D2R_DISABLE2_DISABLE_TIMER 0xCAFEU
	#define U300_WDOG_D2R_DISABLE_STATUS_DISABLED 0xDABEU
	#define U300_WDOG_D2R_DISABLE_STATUS_ENABLED 0x0000U
	/* WDOG_STATUS Register 32bit (R/W) */
	#define U300_WDOG_SR 0x10
	#define U300_WDOG_SR_STATUS_TIMED_OUT 0xCFE8U
	#define U300_WDOG_SR_STATUS_NORMAL 0x0000U
	#define U300_WDOG_SR_RESET_STATUS_RESET 0xE8B4U
	/* WDOG_COUNT Register 32bit (R/-) */
	#define U300_WDOG_CR 0x14
	#define U300_WDOG_CR_VALID_IND 0x8000U
	#define U300_WDOG_CR_VALID_STABLE 0x0000U
	#define U300_WDOG_CR_COUNT_VALUE_MASK 0x7FFFU
	/* WDOG_JTAGOVR Register 32bit (R/W) */
	#define U300_WDOG_JOR 0x18
	#define U300_WDOG_JOR_JTAG_MODE_IND 0x0002U
	#define U300_WDOG_JOR_JTAG_WATCHDOG_ENABLE 0x0001U
	/* WDOG_RESTART Register 32bit (-/W) */
	#define U300_WDOG_RR 0x1C
	#define U300_WDOG_RR_RESTART_VALUE_RESUME 0xACEDU
	/* WDOG_IRQ_EVENT Register 32bit (R/W) */
	#define U300_WDOG_IER 0x20
	#define U300_WDOG_IER_WILL_BARK_IRQ_EVENT_IND 0x0001U
	#define U300_WDOG_IER_WILL_BARK_IRQ_ACK_ENABLE 0x0001U
	/* WDOG_IRQ_MASK Register 32bit (R/W) */
	#define U300_WDOG_IMR 0x24
	#define U300_WDOG_IMR_WILL_BARK_IRQ_ENABLE 0x0001U
	/* WDOG_IRQ_FORCE Register 32bit (R/W) */
	#define U300_WDOG_IFR 0x28
	#define U300_WDOG_IFR_WILL_BARK_IRQ_FORCE_ENABLE 0x0001U

	/* Default timeout in seconds = 1 minute */
	#define U300_WDOG_DEFAULT_TIMEOUT 60

	static unsigned int margin;
	static int irq;
	static void __iomem *virtbase;
	static struct device *parent;

	static struct clk *clk;

	/*
	* Enabling and disabling functions.
	*/
	static void coh901327_enable(u16 timeout)
	{
	u16 val;
	unsigned long freq;
	unsigned long delay_ns;

	/* Restart timer if it is disabled */
	val = readw(virtbase + U300_WDOG_D2R);
	if (val == U300_WDOG_D2R_DISABLE_STATUS_DISABLED)
	writew(U300_WDOG_RR_RESTART_VALUE_RESUME,
	virtbase + U300_WDOG_RR);
	/* Acknowledge any pending interrupt so it doesn't just fire off */
	writew(U300_WDOG_IER_WILL_BARK_IRQ_ACK_ENABLE,
	virtbase + U300_WDOG_IER);
	/*
	* The interrupt is cleared in the 32 kHz clock domain.
	* Wait 3 32 kHz cycles for it to take effect
	*/
	freq = clk_get_rate(clk);
	delay_ns = DIV_ROUND_UP(1000000000, freq); /* Freq to ns and round up */
	delay_ns = 3 * delay_ns; /* Wait 3 cycles */
	ndelay(delay_ns);
	/* Enable the watchdog interrupt */
	writew(U300_WDOG_IMR_WILL_BARK_IRQ_ENABLE, virtbase + U300_WDOG_IMR);
	/* Activate the watchdog timer */
	writew(timeout, virtbase + U300_WDOG_TR);
	/* Start the watchdog timer */
	writew(U300_WDOG_FR_FEED_RESTART_TIMER, virtbase + U300_WDOG_FR);
	/*
	* Extra read so that this change propagate in the watchdog.
	*/
	(void) readw(virtbase + U300_WDOG_CR);
	val = readw(virtbase + U300_WDOG_D2R);
	if (val != U300_WDOG_D2R_DISABLE_STATUS_ENABLED)
	dev_err(parent,
	"%s(): watchdog not enabled! D2R value %04x\n",
	__func__, val);
	}

	static void coh901327_disable(void)
	{
	u16 val;

	/* Disable the watchdog interrupt if it is active */
	writew(0x0000U, virtbase + U300_WDOG_IMR);
	/* If the watchdog is currently enabled, attempt to disable it */
	val = readw(virtbase + U300_WDOG_D2R);
	if (val != U300_WDOG_D2R_DISABLE_STATUS_DISABLED) {
	writew(U300_WDOG_D1R_DISABLE1_DISABLE_TIMER,
	virtbase + U300_WDOG_D1R);
	writew(U300_WDOG_D2R_DISABLE2_DISABLE_TIMER,
	virtbase + U300_WDOG_D2R);
	/* Write this twice (else problems occur) */
	writew(U300_WDOG_D2R_DISABLE2_DISABLE_TIMER,
	virtbase + U300_WDOG_D2R);
	}
	val = readw(virtbase + U300_WDOG_D2R);
	if (val != U300_WDOG_D2R_DISABLE_STATUS_DISABLED)
	dev_err(parent,
	"%s(): watchdog not disabled! D2R value %04x\n",
	__func__, val);
	}

	static int coh901327_start(struct watchdog_device *wdt_dev)
	{
	coh901327_enable(wdt_dev->timeout * 100);
	return 0;
	}

	static int coh901327_stop(struct watchdog_device *wdt_dev)
	{
	coh901327_disable();
	return 0;
	}

	static int coh901327_ping(struct watchdog_device *wdd)
	{
	/* Feed the watchdog */
	writew(U300_WDOG_FR_FEED_RESTART_TIMER,
	virtbase + U300_WDOG_FR);
	return 0;
	}

	static int coh901327_settimeout(struct watchdog_device *wdt_dev,
	unsigned int time)
	{
	wdt_dev->timeout = time;
	/* Set new timeout value */
	writew(time * 100, virtbase + U300_WDOG_TR);
	/* Feed the dog */
	writew(U300_WDOG_FR_FEED_RESTART_TIMER,
	virtbase + U300_WDOG_FR);
	return 0;
	}

	static unsigned int coh901327_gettimeleft(struct watchdog_device *wdt_dev)
	{
	u16 val;

	/* Read repeatedly until the value is stable! */
	val = readw(virtbase + U300_WDOG_CR);
	while (val & U300_WDOG_CR_VALID_IND)
	val = readw(virtbase + U300_WDOG_CR);
	val &= U300_WDOG_CR_COUNT_VALUE_MASK;
	if (val != 0)
	val /= 100;

	return val;
	}

	/*
	* This interrupt occurs 10 ms before the watchdog WILL bark.
	*/
	static irqreturn_t coh901327_interrupt(int irq, void *data)
	{
	u16 val;

	/*
	* Ack IRQ? If this occurs we're FUBAR anyway, so
	* just acknowledge, disable the interrupt and await the imminent end.
	* If you at some point need a host of callbacks to be called
	* when the system is about to watchdog-reset, add them here!
	*
	* NOTE: on future versions of this IP-block, it will be possible
	* to prevent a watchdog reset by feeding the watchdog at this
	* point.
	*/
	val = readw(virtbase + U300_WDOG_IER);
	if (val == U300_WDOG_IER_WILL_BARK_IRQ_EVENT_IND)
	writew(U300_WDOG_IER_WILL_BARK_IRQ_ACK_ENABLE,
	virtbase + U300_WDOG_IER);
	writew(0x0000U, virtbase + U300_WDOG_IMR);
	dev_crit(parent, "watchdog is barking!\n");
	return IRQ_HANDLED;
	}

	static const struct watchdog_info coh901327_ident = {
	.options = WDIOF_CARDRESET \| WDIOF_SETTIMEOUT \| WDIOF_KEEPALIVEPING,
	.identity = DRV_NAME,
	};

	static const struct watchdog_ops coh901327_ops = {
	.owner = THIS_MODULE,
	.start = coh901327_start,
	.stop = coh901327_stop,
	.ping = coh901327_ping,
	.set_timeout = coh901327_settimeout,
	.get_timeleft = coh901327_gettimeleft,
	};

	static struct watchdog_device coh901327_wdt = {
	.info = &coh901327_ident,
	.ops = &coh901327_ops,
	/*
	* Max timeout is 327 since the 10ms
	* timeout register is max
	* 0x7FFF = 327670ms ~= 327s.
	*/
	.min_timeout = 1,
	.max_timeout = 327,
	.timeout = U300_WDOG_DEFAULT_TIMEOUT,
	};

	static int __exit coh901327_remove(struct platform_device *pdev)
	{
	watchdog_unregister_device(&coh901327_wdt);
	coh901327_disable();
	free_irq(irq, pdev);
	clk_disable_unprepare(clk);
	clk_put(clk);
	return 0;
	}

	static int __init coh901327_probe(struct platform_device *pdev)
	{
	struct device *dev = &pdev->dev;
	int ret;
	u16 val;
	struct resource *res;

	parent = dev;

	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
	virtbase = devm_ioremap_resource(dev, res);
	if (IS_ERR(virtbase))
	return PTR_ERR(virtbase);

	clk = clk_get(dev, NULL);
	if (IS_ERR(clk)) {
	ret = PTR_ERR(clk);
	dev_err(dev, "could not get clock\n");
	return ret;
	}
	ret = clk_prepare_enable(clk);
	if (ret) {
	dev_err(dev, "could not prepare and enable clock\n");
	goto out_no_clk_enable;
	}

	val = readw(virtbase + U300_WDOG_SR);
	switch (val) {
	case U300_WDOG_SR_STATUS_TIMED_OUT:
	dev_info(dev, "watchdog timed out since last chip reset!\n");
	coh901327_wdt.bootstatus \|= WDIOF_CARDRESET;
	/* Status will be cleared below */
	break;
	case U300_WDOG_SR_STATUS_NORMAL:
	dev_info(dev, "in normal status, no timeouts have occurred.\n");
	break;
	default:
	dev_info(dev, "contains an illegal status code (%08x)\n", val);
	break;
	}

	val = readw(virtbase + U300_WDOG_D2R);
	switch (val) {
	case U300_WDOG_D2R_DISABLE_STATUS_DISABLED:
	dev_info(dev, "currently disabled.\n");
	break;
	case U300_WDOG_D2R_DISABLE_STATUS_ENABLED:
	dev_info(dev, "currently enabled! (disabling it now)\n");
	coh901327_disable();
	break;
	default:
	dev_err(dev, "contains an illegal enable/disable code (%08x)\n",
	val);
	break;
	}

	/* Reset the watchdog */
	writew(U300_WDOG_SR_RESET_STATUS_RESET, virtbase + U300_WDOG_SR);

	irq = platform_get_irq(pdev, 0);
	if (request_irq(irq, coh901327_interrupt, 0,
	DRV_NAME " Bark", pdev)) {
	ret = -EIO;
	goto out_no_irq;
	}

	watchdog_init_timeout(&coh901327_wdt, margin, dev);

	coh901327_wdt.parent = dev;
	ret = watchdog_register_device(&coh901327_wdt);
	if (ret)
	goto out_no_wdog;

	dev_info(dev, "initialized. (timeout=%d sec)\n",
	coh901327_wdt.timeout);
	return 0;

	out_no_wdog:
	free_irq(irq, pdev);
	out_no_irq:
	clk_disable_unprepare(clk);
	out_no_clk_enable:
	clk_put(clk);
	return ret;
	}

	#ifdef CONFIG_PM

	static u16 wdogenablestore;
	static u16 irqmaskstore;

	static int coh901327_suspend(struct platform_device *pdev, pm_message_t state)
	{
	irqmaskstore = readw(virtbase + U300_WDOG_IMR) & 0x0001U;
	wdogenablestore = readw(virtbase + U300_WDOG_D2R);
	/* If watchdog is on, disable it here and now */
	if (wdogenablestore == U300_WDOG_D2R_DISABLE_STATUS_ENABLED)
	coh901327_disable();
	return 0;
	}

	static int coh901327_resume(struct platform_device *pdev)
	{
	/* Restore the watchdog interrupt */
	writew(irqmaskstore, virtbase + U300_WDOG_IMR);
	if (wdogenablestore == U300_WDOG_D2R_DISABLE_STATUS_ENABLED) {
	/* Restart the watchdog timer */
	writew(U300_WDOG_RR_RESTART_VALUE_RESUME,
	virtbase + U300_WDOG_RR);
	writew(U300_WDOG_FR_FEED_RESTART_TIMER,
	virtbase + U300_WDOG_FR);
	}
	return 0;
	}
	#else
	#define coh901327_suspend NULL
	#define coh901327_resume NULL
	#endif

	/*
	* Mistreating the watchdog is the only way to perform a software reset of the
	* system on EMP platforms. So we implement this and export a symbol for it.
	*/
	void coh901327_watchdog_reset(void)
	{
	/* Enable even if on JTAG too */
	writew(U300_WDOG_JOR_JTAG_WATCHDOG_ENABLE,
	virtbase + U300_WDOG_JOR);
	/*
	* Timeout = 5s, we have to wait for the watchdog reset to
	* actually take place: the watchdog will be reloaded with the
	* default value immediately, so we HAVE to reboot and get back
	* into the kernel in 30s, or the device will reboot again!
	* The boot loader will typically deactivate the watchdog, so we
	* need time enough for the boot loader to get to the point of
	* deactivating the watchdog before it is shut down by it.
	*
	* NOTE: on future versions of the watchdog, this restriction is
	* gone: the watchdog will be reloaded with a default value (1 min)
	* instead of last value, and you can conveniently set the watchdog
	* timeout to 10ms (value = 1) without any problems.
	*/
	coh901327_enable(500);
	/* Return and await doom */
	}

	static const struct of_device_id coh901327_dt_match[] = {
	{ .compatible = "stericsson,coh901327" },
	{},
	};

	static struct platform_driver coh901327_driver = {
	.driver = {
	.name = "coh901327_wdog",
	.of_match_table = coh901327_dt_match,
	},
	.remove = __exit_p(coh901327_remove),
	.suspend = coh901327_suspend,
	.resume = coh901327_resume,
	};

	module_platform_driver_probe(coh901327_driver, coh901327_probe);

	MODULE_AUTHOR("Linus Walleij <linus.walleij@stericsson.com>");
	MODULE_DESCRIPTION("COH 901 327 Watchdog");

	module_param(margin, uint, 0);
	MODULE_PARM_DESC(margin, "Watchdog margin in seconds (default 60s)");

	MODULE_LICENSE("GPL v2");
	MODULE_ALIAS("platform:coh901327-watchdog");