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

 /*
  * Copyright 2010-2011 Picochip Ltd., Jamie Iles
  * http://www.picochip.com
  *
  * 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.
  *
  * This file implements a driver for the Synopsys DesignWare watchdog device
  * in the many subsystems. The watchdog has 16 different timeout periods
  * and these are a function of the input clock frequency.
  *
  * The DesignWare watchdog cannot be stopped once it has been started so we
  * do not implement a stop function. The watchdog core will continue to send
  * heartbeat requests after the watchdog device has been closed.
  */

 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

 #include <linux/bitops.h>
 #include <linux/clk.h>
 #include <linux/delay.h>
 #include <linux/err.h>
 #include <linux/io.h>
 #include <linux/kernel.h>
 #include <linux/module.h>
 #include <linux/moduleparam.h>
 #include <linux/of.h>
 #include <linux/pm.h>
 #include <linux/platform_device.h>
 #include <linux/reset.h>
 #include <linux/watchdog.h>

 #define WDOG_CONTROL_REG_OFFSET		    0x00
 #define WDOG_CONTROL_REG_WDT_EN_MASK	    0x01
 #define WDOG_CONTROL_REG_RESP_MODE_MASK	    0x02
 #define WDOG_TIMEOUT_RANGE_REG_OFFSET	    0x04
 #define WDOG_TIMEOUT_RANGE_TOPINIT_SHIFT    4
 #define WDOG_CURRENT_COUNT_REG_OFFSET	    0x08
 #define WDOG_COUNTER_RESTART_REG_OFFSET     0x0c
 #define WDOG_COUNTER_RESTART_KICK_VALUE	    0x76

 /* The maximum TOP (timeout period) value that can be set in the watchdog. */
 #define DW_WDT_MAX_TOP		15

 #define DW_WDT_DEFAULT_SECONDS	30

 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) ")");

 struct dw_wdt {
 	void __iomem		*regs;
 	struct clk		*clk;
 	unsigned long		rate;
 	struct watchdog_device	wdd;
 	struct reset_control	*rst;
 	/* Save/restore */
 	u32			control;
 	u32			timeout;
 };

 #define to_dw_wdt(wdd)	container_of(wdd, struct dw_wdt, wdd)

 static inline int dw_wdt_is_enabled(struct dw_wdt *dw_wdt)
 {
 	return readl(dw_wdt->regs + WDOG_CONTROL_REG_OFFSET) &
 		WDOG_CONTROL_REG_WDT_EN_MASK;
 }

 static inline int dw_wdt_top_in_seconds(struct dw_wdt *dw_wdt, unsigned top)
 {
 	/*
 	 * There are 16 possible timeout values in 0..15 where the number of
 	 * cycles is 2 ^ (16 + i) and the watchdog counts down.
 	 */
 	return (1U << (16 + top)) / dw_wdt->rate;
 }

 static int dw_wdt_get_top(struct dw_wdt *dw_wdt)
 {
 	int top = readl(dw_wdt->regs + WDOG_TIMEOUT_RANGE_REG_OFFSET) & 0xF;

 	return dw_wdt_top_in_seconds(dw_wdt, top);
 }

 static int dw_wdt_ping(struct watchdog_device *wdd)
 {
 	struct dw_wdt *dw_wdt = to_dw_wdt(wdd);

 	writel(WDOG_COUNTER_RESTART_KICK_VALUE, dw_wdt->regs +
 	       WDOG_COUNTER_RESTART_REG_OFFSET);

 	return 0;
 }

 static int dw_wdt_set_timeout(struct watchdog_device *wdd, unsigned int top_s)
 {
 	struct dw_wdt *dw_wdt = to_dw_wdt(wdd);
 	int i, top_val = DW_WDT_MAX_TOP;

 	/*
 	 * Iterate over the timeout values until we find the closest match. We
 	 * always look for >=.
 	 */
 	for (i = 0; i <= DW_WDT_MAX_TOP; ++i)
 		if (dw_wdt_top_in_seconds(dw_wdt, i) >= top_s) {
 			top_val = i;
 			break;
 		}

 	/*
 	 * Set the new value in the watchdog.  Some versions of dw_wdt
 	 * have have TOPINIT in the TIMEOUT_RANGE register (as per
 	 * CP_WDT_DUAL_TOP in WDT_COMP_PARAMS_1).  On those we
 	 * effectively get a pat of the watchdog right here.
 	 */
 	writel(top_val | top_val << WDOG_TIMEOUT_RANGE_TOPINIT_SHIFT,
 	       dw_wdt->regs + WDOG_TIMEOUT_RANGE_REG_OFFSET);

 	wdd->timeout = dw_wdt_top_in_seconds(dw_wdt, top_val);

 	return 0;
 }

 static void dw_wdt_arm_system_reset(struct dw_wdt *dw_wdt)
 {
 	u32 val = readl(dw_wdt->regs + WDOG_CONTROL_REG_OFFSET);

 	/* Disable interrupt mode; always perform system reset. */
 	val &= ~WDOG_CONTROL_REG_RESP_MODE_MASK;
 	/* Enable watchdog. */
 	val |= WDOG_CONTROL_REG_WDT_EN_MASK;
 	writel(val, dw_wdt->regs + WDOG_CONTROL_REG_OFFSET);
 }

 static int dw_wdt_start(struct watchdog_device *wdd)
 {
 	struct dw_wdt *dw_wdt = to_dw_wdt(wdd);

 	dw_wdt_set_timeout(wdd, wdd->timeout);
 	dw_wdt_arm_system_reset(dw_wdt);

 	return 0;
 }

 static int dw_wdt_stop(struct watchdog_device *wdd)
 {
 	struct dw_wdt *dw_wdt = to_dw_wdt(wdd);

 	if (!dw_wdt->rst) {
 		set_bit(WDOG_HW_RUNNING, &wdd->status);
 		return 0;
 	}

 	reset_control_assert(dw_wdt->rst);
 	reset_control_deassert(dw_wdt->rst);

 	return 0;
 }

 static int dw_wdt_restart(struct watchdog_device *wdd,
 			  unsigned long action, void *data)
 {
 	struct dw_wdt *dw_wdt = to_dw_wdt(wdd);

 	writel(0, dw_wdt->regs + WDOG_TIMEOUT_RANGE_REG_OFFSET);
 	if (dw_wdt_is_enabled(dw_wdt))
 		writel(WDOG_COUNTER_RESTART_KICK_VALUE,
 		       dw_wdt->regs + WDOG_COUNTER_RESTART_REG_OFFSET);
 	else
 		dw_wdt_arm_system_reset(dw_wdt);

 	/* wait for reset to assert... */
 	mdelay(500);

 	return 0;
 }

 static unsigned int dw_wdt_get_timeleft(struct watchdog_device *wdd)
 {
 	struct dw_wdt *dw_wdt = to_dw_wdt(wdd);

 	return readl(dw_wdt->regs + WDOG_CURRENT_COUNT_REG_OFFSET) /
 		dw_wdt->rate;
 }

 static const struct watchdog_info dw_wdt_ident = {
 	.options	= WDIOF_KEEPALIVEPING | WDIOF_SETTIMEOUT |
 			  WDIOF_MAGICCLOSE,
 	.identity	= "Synopsys DesignWare Watchdog",
 };

 static const struct watchdog_ops dw_wdt_ops = {
 	.owner		= THIS_MODULE,
 	.start		= dw_wdt_start,
 	.stop		= dw_wdt_stop,
 	.ping		= dw_wdt_ping,
 	.set_timeout	= dw_wdt_set_timeout,
 	.get_timeleft	= dw_wdt_get_timeleft,
 	.restart	= dw_wdt_restart,
 };

 #ifdef CONFIG_PM_SLEEP
 static int dw_wdt_suspend(struct device *dev)
 {
 	struct dw_wdt *dw_wdt = dev_get_drvdata(dev);

 	dw_wdt->control = readl(dw_wdt->regs + WDOG_CONTROL_REG_OFFSET);
 	dw_wdt->timeout = readl(dw_wdt->regs + WDOG_TIMEOUT_RANGE_REG_OFFSET);

 	clk_disable_unprepare(dw_wdt->clk);

 	return 0;
 }

 static int dw_wdt_resume(struct device *dev)
 {
 	struct dw_wdt *dw_wdt = dev_get_drvdata(dev);
 	int err = clk_prepare_enable(dw_wdt->clk);

 	if (err)
 		return err;

 	writel(dw_wdt->timeout, dw_wdt->regs + WDOG_TIMEOUT_RANGE_REG_OFFSET);
 	writel(dw_wdt->control, dw_wdt->regs + WDOG_CONTROL_REG_OFFSET);

 	dw_wdt_ping(&dw_wdt->wdd);

 	return 0;
 }
 #endif /* CONFIG_PM_SLEEP */

 static SIMPLE_DEV_PM_OPS(dw_wdt_pm_ops, dw_wdt_suspend, dw_wdt_resume);

 static int dw_wdt_drv_probe(struct platform_device *pdev)
 {
 	struct device *dev = &pdev->dev;
 	struct watchdog_device *wdd;
 	struct dw_wdt *dw_wdt;
 	struct resource *mem;
 	int ret;

 	dw_wdt = devm_kzalloc(dev, sizeof(*dw_wdt), GFP_KERNEL);
 	if (!dw_wdt)
 		return -ENOMEM;

 	mem = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 	dw_wdt->regs = devm_ioremap_resource(dev, mem);
 	if (IS_ERR(dw_wdt->regs))
 		return PTR_ERR(dw_wdt->regs);

 	dw_wdt->clk = devm_clk_get(dev, NULL);
 	if (IS_ERR(dw_wdt->clk))
 		return PTR_ERR(dw_wdt->clk);

 	ret = clk_prepare_enable(dw_wdt->clk);
 	if (ret)
 		return ret;

 	dw_wdt->rate = clk_get_rate(dw_wdt->clk);
 	if (dw_wdt->rate == 0) {
 		ret = -EINVAL;
 		goto out_disable_clk;
 	}

 	dw_wdt->rst = devm_reset_control_get_optional_shared(&pdev->dev, NULL);
 	if (IS_ERR(dw_wdt->rst)) {
 		ret = PTR_ERR(dw_wdt->rst);
 		goto out_disable_clk;
 	}

 	reset_control_deassert(dw_wdt->rst);

 	wdd = &dw_wdt->wdd;
 	wdd->info = &dw_wdt_ident;
 	wdd->ops = &dw_wdt_ops;
 	wdd->min_timeout = 1;
 	wdd->max_hw_heartbeat_ms =
 		dw_wdt_top_in_seconds(dw_wdt, DW_WDT_MAX_TOP) * 1000;
 	wdd->parent = dev;

 	watchdog_set_drvdata(wdd, dw_wdt);
 	watchdog_set_nowayout(wdd, nowayout);
 	watchdog_init_timeout(wdd, 0, dev);

 	/*
 	 * If the watchdog is already running, use its already configured
 	 * timeout. Otherwise use the default or the value provided through
 	 * devicetree.
 	 */
 	if (dw_wdt_is_enabled(dw_wdt)) {
 		wdd->timeout = dw_wdt_get_top(dw_wdt);
 		set_bit(WDOG_HW_RUNNING, &wdd->status);
 	} else {
 		wdd->timeout = DW_WDT_DEFAULT_SECONDS;
 		watchdog_init_timeout(wdd, 0, dev);
 	}

 	platform_set_drvdata(pdev, dw_wdt);

 	watchdog_set_restart_priority(wdd, 128);

 	ret = watchdog_register_device(wdd);
 	if (ret)
 		goto out_disable_clk;

 	return 0;

 out_disable_clk:
 	clk_disable_unprepare(dw_wdt->clk);
 	return ret;
 }

 static int dw_wdt_drv_remove(struct platform_device *pdev)
 {
 	struct dw_wdt *dw_wdt = platform_get_drvdata(pdev);

 	watchdog_unregister_device(&dw_wdt->wdd);
 	reset_control_assert(dw_wdt->rst);
 	clk_disable_unprepare(dw_wdt->clk);

 	return 0;
 }

 #ifdef CONFIG_OF
 static const struct of_device_id dw_wdt_of_match[] = {
 	{ .compatible = "snps,dw-wdt", },
 	{ /* sentinel */ }
 };
 MODULE_DEVICE_TABLE(of, dw_wdt_of_match);
 #endif

 static struct platform_driver dw_wdt_driver = {
 	.probe		= dw_wdt_drv_probe,
 	.remove		= dw_wdt_drv_remove,
 	.driver		= {
 		.name	= "dw_wdt",
 		.of_match_table = of_match_ptr(dw_wdt_of_match),
 		.pm	= &dw_wdt_pm_ops,
 	},
 };

 module_platform_driver(dw_wdt_driver);

 MODULE_AUTHOR("Jamie Iles");
 MODULE_DESCRIPTION("Synopsys DesignWare Watchdog Driver");
 MODULE_LICENSE("GPL");
	/*
	* Copyright 2010-2011 Picochip Ltd., Jamie Iles
	* http://www.picochip.com
	*
	* 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.
	*
	* This file implements a driver for the Synopsys DesignWare watchdog device
	* in the many subsystems. The watchdog has 16 different timeout periods
	* and these are a function of the input clock frequency.
	*
	* The DesignWare watchdog cannot be stopped once it has been started so we
	* do not implement a stop function. The watchdog core will continue to send
	* heartbeat requests after the watchdog device has been closed.
	*/

	#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

	#include <linux/bitops.h>
	#include <linux/clk.h>
	#include <linux/delay.h>
	#include <linux/err.h>
	#include <linux/io.h>
	#include <linux/kernel.h>
	#include <linux/module.h>
	#include <linux/moduleparam.h>
	#include <linux/of.h>
	#include <linux/pm.h>
	#include <linux/platform_device.h>
	#include <linux/reset.h>
	#include <linux/watchdog.h>

	#define WDOG_CONTROL_REG_OFFSET 0x00
	#define WDOG_CONTROL_REG_WDT_EN_MASK 0x01
	#define WDOG_CONTROL_REG_RESP_MODE_MASK 0x02
	#define WDOG_TIMEOUT_RANGE_REG_OFFSET 0x04
	#define WDOG_TIMEOUT_RANGE_TOPINIT_SHIFT 4
	#define WDOG_CURRENT_COUNT_REG_OFFSET 0x08
	#define WDOG_COUNTER_RESTART_REG_OFFSET 0x0c
	#define WDOG_COUNTER_RESTART_KICK_VALUE 0x76

	/* The maximum TOP (timeout period) value that can be set in the watchdog. */
	#define DW_WDT_MAX_TOP 15

	#define DW_WDT_DEFAULT_SECONDS 30

	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) ")");

	struct dw_wdt {
	void __iomem *regs;
	struct clk *clk;
	unsigned long rate;
	struct watchdog_device wdd;
	struct reset_control *rst;
	/* Save/restore */
	u32 control;
	u32 timeout;
	};

	#define to_dw_wdt(wdd) container_of(wdd, struct dw_wdt, wdd)

	static inline int dw_wdt_is_enabled(struct dw_wdt *dw_wdt)
	{
	return readl(dw_wdt->regs + WDOG_CONTROL_REG_OFFSET) &
	WDOG_CONTROL_REG_WDT_EN_MASK;
	}

	static inline int dw_wdt_top_in_seconds(struct dw_wdt *dw_wdt, unsigned top)
	{
	/*
	* There are 16 possible timeout values in 0..15 where the number of
	* cycles is 2 ^ (16 + i) and the watchdog counts down.
	*/
	return (1U << (16 + top)) / dw_wdt->rate;
	}

	static int dw_wdt_get_top(struct dw_wdt *dw_wdt)
	{
	int top = readl(dw_wdt->regs + WDOG_TIMEOUT_RANGE_REG_OFFSET) & 0xF;

	return dw_wdt_top_in_seconds(dw_wdt, top);
	}

	static int dw_wdt_ping(struct watchdog_device *wdd)
	{
	struct dw_wdt *dw_wdt = to_dw_wdt(wdd);

	writel(WDOG_COUNTER_RESTART_KICK_VALUE, dw_wdt->regs +
	WDOG_COUNTER_RESTART_REG_OFFSET);

	return 0;
	}

	static int dw_wdt_set_timeout(struct watchdog_device *wdd, unsigned int top_s)
	{
	struct dw_wdt *dw_wdt = to_dw_wdt(wdd);
	int i, top_val = DW_WDT_MAX_TOP;

	/*
	* Iterate over the timeout values until we find the closest match. We
	* always look for >=.
	*/
	for (i = 0; i <= DW_WDT_MAX_TOP; ++i)
	if (dw_wdt_top_in_seconds(dw_wdt, i) >= top_s) {
	top_val = i;
	break;
	}

	/*
	* Set the new value in the watchdog. Some versions of dw_wdt
	* have have TOPINIT in the TIMEOUT_RANGE register (as per
	* CP_WDT_DUAL_TOP in WDT_COMP_PARAMS_1). On those we
	* effectively get a pat of the watchdog right here.
	*/
	writel(top_val \| top_val << WDOG_TIMEOUT_RANGE_TOPINIT_SHIFT,
	dw_wdt->regs + WDOG_TIMEOUT_RANGE_REG_OFFSET);

	wdd->timeout = dw_wdt_top_in_seconds(dw_wdt, top_val);

	return 0;
	}

	static void dw_wdt_arm_system_reset(struct dw_wdt *dw_wdt)
	{
	u32 val = readl(dw_wdt->regs + WDOG_CONTROL_REG_OFFSET);

	/* Disable interrupt mode; always perform system reset. */
	val &= ~WDOG_CONTROL_REG_RESP_MODE_MASK;
	/* Enable watchdog. */
	val \|= WDOG_CONTROL_REG_WDT_EN_MASK;
	writel(val, dw_wdt->regs + WDOG_CONTROL_REG_OFFSET);
	}

	static int dw_wdt_start(struct watchdog_device *wdd)
	{
	struct dw_wdt *dw_wdt = to_dw_wdt(wdd);

	dw_wdt_set_timeout(wdd, wdd->timeout);
	dw_wdt_arm_system_reset(dw_wdt);

	return 0;
	}

	static int dw_wdt_stop(struct watchdog_device *wdd)
	{
	struct dw_wdt *dw_wdt = to_dw_wdt(wdd);

	if (!dw_wdt->rst) {
	set_bit(WDOG_HW_RUNNING, &wdd->status);
	return 0;
	}

	reset_control_assert(dw_wdt->rst);
	reset_control_deassert(dw_wdt->rst);

	return 0;
	}

	static int dw_wdt_restart(struct watchdog_device *wdd,
	unsigned long action, void *data)
	{
	struct dw_wdt *dw_wdt = to_dw_wdt(wdd);

	writel(0, dw_wdt->regs + WDOG_TIMEOUT_RANGE_REG_OFFSET);
	if (dw_wdt_is_enabled(dw_wdt))
	writel(WDOG_COUNTER_RESTART_KICK_VALUE,
	dw_wdt->regs + WDOG_COUNTER_RESTART_REG_OFFSET);
	else
	dw_wdt_arm_system_reset(dw_wdt);

	/* wait for reset to assert... */
	mdelay(500);

	return 0;
	}

	static unsigned int dw_wdt_get_timeleft(struct watchdog_device *wdd)
	{
	struct dw_wdt *dw_wdt = to_dw_wdt(wdd);

	return readl(dw_wdt->regs + WDOG_CURRENT_COUNT_REG_OFFSET) /
	dw_wdt->rate;
	}

	static const struct watchdog_info dw_wdt_ident = {
	.options = WDIOF_KEEPALIVEPING \| WDIOF_SETTIMEOUT \|
	WDIOF_MAGICCLOSE,
	.identity = "Synopsys DesignWare Watchdog",
	};

	static const struct watchdog_ops dw_wdt_ops = {
	.owner = THIS_MODULE,
	.start = dw_wdt_start,
	.stop = dw_wdt_stop,
	.ping = dw_wdt_ping,
	.set_timeout = dw_wdt_set_timeout,
	.get_timeleft = dw_wdt_get_timeleft,
	.restart = dw_wdt_restart,
	};

	#ifdef CONFIG_PM_SLEEP
	static int dw_wdt_suspend(struct device *dev)
	{
	struct dw_wdt *dw_wdt = dev_get_drvdata(dev);

	dw_wdt->control = readl(dw_wdt->regs + WDOG_CONTROL_REG_OFFSET);
	dw_wdt->timeout = readl(dw_wdt->regs + WDOG_TIMEOUT_RANGE_REG_OFFSET);

	clk_disable_unprepare(dw_wdt->clk);

	return 0;
	}

	static int dw_wdt_resume(struct device *dev)
	{
	struct dw_wdt *dw_wdt = dev_get_drvdata(dev);
	int err = clk_prepare_enable(dw_wdt->clk);

	if (err)
	return err;

	writel(dw_wdt->timeout, dw_wdt->regs + WDOG_TIMEOUT_RANGE_REG_OFFSET);
	writel(dw_wdt->control, dw_wdt->regs + WDOG_CONTROL_REG_OFFSET);

	dw_wdt_ping(&dw_wdt->wdd);

	return 0;
	}
	#endif /* CONFIG_PM_SLEEP */

	static SIMPLE_DEV_PM_OPS(dw_wdt_pm_ops, dw_wdt_suspend, dw_wdt_resume);

	static int dw_wdt_drv_probe(struct platform_device *pdev)
	{
	struct device *dev = &pdev->dev;
	struct watchdog_device *wdd;
	struct dw_wdt *dw_wdt;
	struct resource *mem;
	int ret;

	dw_wdt = devm_kzalloc(dev, sizeof(*dw_wdt), GFP_KERNEL);
	if (!dw_wdt)
	return -ENOMEM;

	mem = platform_get_resource(pdev, IORESOURCE_MEM, 0);
	dw_wdt->regs = devm_ioremap_resource(dev, mem);
	if (IS_ERR(dw_wdt->regs))
	return PTR_ERR(dw_wdt->regs);

	dw_wdt->clk = devm_clk_get(dev, NULL);
	if (IS_ERR(dw_wdt->clk))
	return PTR_ERR(dw_wdt->clk);

	ret = clk_prepare_enable(dw_wdt->clk);
	if (ret)
	return ret;

	dw_wdt->rate = clk_get_rate(dw_wdt->clk);
	if (dw_wdt->rate == 0) {
	ret = -EINVAL;
	goto out_disable_clk;
	}

	dw_wdt->rst = devm_reset_control_get_optional_shared(&pdev->dev, NULL);
	if (IS_ERR(dw_wdt->rst)) {
	ret = PTR_ERR(dw_wdt->rst);
	goto out_disable_clk;
	}

	reset_control_deassert(dw_wdt->rst);

	wdd = &dw_wdt->wdd;
	wdd->info = &dw_wdt_ident;
	wdd->ops = &dw_wdt_ops;
	wdd->min_timeout = 1;
	wdd->max_hw_heartbeat_ms =
	dw_wdt_top_in_seconds(dw_wdt, DW_WDT_MAX_TOP) * 1000;
	wdd->parent = dev;

	watchdog_set_drvdata(wdd, dw_wdt);
	watchdog_set_nowayout(wdd, nowayout);
	watchdog_init_timeout(wdd, 0, dev);

	/*
	* If the watchdog is already running, use its already configured
	* timeout. Otherwise use the default or the value provided through
	* devicetree.
	*/
	if (dw_wdt_is_enabled(dw_wdt)) {
	wdd->timeout = dw_wdt_get_top(dw_wdt);
	set_bit(WDOG_HW_RUNNING, &wdd->status);
	} else {
	wdd->timeout = DW_WDT_DEFAULT_SECONDS;
	watchdog_init_timeout(wdd, 0, dev);
	}

	platform_set_drvdata(pdev, dw_wdt);

	watchdog_set_restart_priority(wdd, 128);

	ret = watchdog_register_device(wdd);
	if (ret)
	goto out_disable_clk;

	return 0;

	out_disable_clk:
	clk_disable_unprepare(dw_wdt->clk);
	return ret;
	}

	static int dw_wdt_drv_remove(struct platform_device *pdev)
	{
	struct dw_wdt *dw_wdt = platform_get_drvdata(pdev);

	watchdog_unregister_device(&dw_wdt->wdd);
	reset_control_assert(dw_wdt->rst);
	clk_disable_unprepare(dw_wdt->clk);

	return 0;
	}

	#ifdef CONFIG_OF
	static const struct of_device_id dw_wdt_of_match[] = {
	{ .compatible = "snps,dw-wdt", },
	{ /* sentinel */ }
	};
	MODULE_DEVICE_TABLE(of, dw_wdt_of_match);
	#endif

	static struct platform_driver dw_wdt_driver = {
	.probe = dw_wdt_drv_probe,
	.remove = dw_wdt_drv_remove,
	.driver = {
	.name = "dw_wdt",
	.of_match_table = of_match_ptr(dw_wdt_of_match),
	.pm = &dw_wdt_pm_ops,
	},
	};

	module_platform_driver(dw_wdt_driver);

	MODULE_AUTHOR("Jamie Iles");
	MODULE_DESCRIPTION("Synopsys DesignWare Watchdog Driver");
	MODULE_LICENSE("GPL");