drivers/watchdog/kempld_wdt.c - kernel/msm-5.4 - Gitiles

 /*
  * Kontron PLD watchdog driver
  *
  * Copyright (c) 2010-2013 Kontron Europe GmbH
  * Author: Michael Brunner <michael.brunner@kontron.com>
  *
  * This program is free software; you can redistribute it and/or modify
  * it under the terms of the GNU General Public License 2 as published
  * by the Free Software Foundation.
  *
  * This program is distributed in the hope that it will be useful,
  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  * GNU General Public License for more details.
  *
  * Note: From the PLD watchdog point of view timeout and pretimeout are
  *       defined differently than in the kernel.
  *       First the pretimeout stage runs out before the timeout stage gets
  *       active.
  *
  * Kernel/API:                     P-----| pretimeout
  *               |-----------------------T timeout
  * Watchdog:     |-----------------P       pretimeout_stage
  *                                 |-----T timeout_stage
  */

 #include <linux/module.h>
 #include <linux/moduleparam.h>
 #include <linux/miscdevice.h>
 #include <linux/uaccess.h>
 #include <linux/watchdog.h>
 #include <linux/platform_device.h>
 #include <linux/mfd/kempld.h>

 #define KEMPLD_WDT_STAGE_TIMEOUT(x)	(0x1b + (x) * 4)
 #define KEMPLD_WDT_STAGE_CFG(x)		(0x18 + (x))
 #define STAGE_CFG_GET_PRESCALER(x)	(((x) & 0x30) >> 4)
 #define STAGE_CFG_SET_PRESCALER(x)	(((x) & 0x3) << 4)
 #define STAGE_CFG_PRESCALER_MASK	0x30
 #define STAGE_CFG_ACTION_MASK		0x7
 #define STAGE_CFG_ASSERT		(1 << 3)

 #define KEMPLD_WDT_MAX_STAGES		2
 #define KEMPLD_WDT_KICK			0x16
 #define KEMPLD_WDT_CFG			0x17
 #define KEMPLD_WDT_CFG_ENABLE		0x10
 #define KEMPLD_WDT_CFG_ENABLE_LOCK	0x8
 #define KEMPLD_WDT_CFG_GLOBAL_LOCK	0x80

 enum {
 	ACTION_NONE = 0,
 	ACTION_RESET,
 	ACTION_NMI,
 	ACTION_SMI,
 	ACTION_SCI,
 	ACTION_DELAY,
 };

 enum {
 	STAGE_TIMEOUT = 0,
 	STAGE_PRETIMEOUT,
 };

 enum {
 	PRESCALER_21 = 0,
 	PRESCALER_17,
 	PRESCALER_12,
 };

 const u32 kempld_prescaler[] = {
 	[PRESCALER_21] = (1 << 21) - 1,
 	[PRESCALER_17] = (1 << 17) - 1,
 	[PRESCALER_12] = (1 << 12) - 1,
 	0,
 };

 struct kempld_wdt_stage {
 	unsigned int	id;
 	u32		mask;
 };

 struct kempld_wdt_data {
 	struct kempld_device_data	*pld;
 	struct watchdog_device		wdd;
 	unsigned int			pretimeout;
 	struct kempld_wdt_stage		stage[KEMPLD_WDT_MAX_STAGES];
 #ifdef CONFIG_PM
 	u8				pm_status_store;
 #endif
 };

 #define DEFAULT_TIMEOUT		30 /* seconds */
 #define DEFAULT_PRETIMEOUT	0

 static unsigned int timeout = DEFAULT_TIMEOUT;
 module_param(timeout, uint, 0);
 MODULE_PARM_DESC(timeout,
 	"Watchdog timeout in seconds. (>=0, default="
 	__MODULE_STRING(DEFAULT_TIMEOUT) ")");

 static unsigned int pretimeout = DEFAULT_PRETIMEOUT;
 module_param(pretimeout, uint, 0);
 MODULE_PARM_DESC(pretimeout,
 	"Watchdog pretimeout in seconds. (>=0, default="
 	__MODULE_STRING(DEFAULT_PRETIMEOUT) ")");

 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) ")");

 static int kempld_wdt_set_stage_action(struct kempld_wdt_data *wdt_data,
 					struct kempld_wdt_stage *stage,
 					u8 action)
 {
 	struct kempld_device_data *pld = wdt_data->pld;
 	u8 stage_cfg;

 	if (!stage || !stage->mask)
 		return -EINVAL;

 	kempld_get_mutex(pld);
 	stage_cfg = kempld_read8(pld, KEMPLD_WDT_STAGE_CFG(stage->id));
 	stage_cfg &= ~STAGE_CFG_ACTION_MASK;
 	stage_cfg |= (action & STAGE_CFG_ACTION_MASK);

 	if (action == ACTION_RESET)
 		stage_cfg |= STAGE_CFG_ASSERT;
 	else
 		stage_cfg &= ~STAGE_CFG_ASSERT;

 	kempld_write8(pld, KEMPLD_WDT_STAGE_CFG(stage->id), stage_cfg);
 	kempld_release_mutex(pld);

 	return 0;
 }

 static int kempld_wdt_set_stage_timeout(struct kempld_wdt_data *wdt_data,
 					struct kempld_wdt_stage *stage,
 					unsigned int timeout)
 {
 	struct kempld_device_data *pld = wdt_data->pld;
 	u32 prescaler = kempld_prescaler[PRESCALER_21];
 	u64 stage_timeout64;
 	u32 stage_timeout;
 	u32 remainder;
 	u8 stage_cfg;

 	if (!stage)
 		return -EINVAL;

 	stage_timeout64 = (u64)timeout * pld->pld_clock;
 	remainder = do_div(stage_timeout64, prescaler);
 	if (remainder)
 		stage_timeout64++;

 	if (stage_timeout64 > stage->mask)
 		return -EINVAL;

 	stage_timeout = stage_timeout64 & stage->mask;

 	kempld_get_mutex(pld);
 	stage_cfg = kempld_read8(pld, KEMPLD_WDT_STAGE_CFG(stage->id));
 	stage_cfg &= ~STAGE_CFG_PRESCALER_MASK;
 	stage_cfg |= STAGE_CFG_SET_PRESCALER(prescaler);
 	kempld_write8(pld, KEMPLD_WDT_STAGE_CFG(stage->id), stage_cfg);
 	kempld_write32(pld, KEMPLD_WDT_STAGE_TIMEOUT(stage->id),
 			stage_timeout);
 	kempld_release_mutex(pld);

 	return 0;
 }

 /*
  * kempld_get_mutex must be called prior to calling this function.
  */
 static unsigned int kempld_wdt_get_timeout(struct kempld_wdt_data *wdt_data,
 						struct kempld_wdt_stage *stage)
 {
 	struct kempld_device_data *pld = wdt_data->pld;
 	unsigned int timeout;
 	u64 stage_timeout;
 	u32 prescaler;
 	u32 remainder;
 	u8 stage_cfg;

 	if (!stage->mask)
 		return 0;

 	stage_cfg = kempld_read8(pld, KEMPLD_WDT_STAGE_CFG(stage->id));
 	stage_timeout = kempld_read32(pld, KEMPLD_WDT_STAGE_TIMEOUT(stage->id));
 	prescaler = kempld_prescaler[STAGE_CFG_GET_PRESCALER(stage_cfg)];

 	stage_timeout = (stage_timeout & stage->mask) * prescaler;
 	remainder = do_div(stage_timeout, pld->pld_clock);
 	if (remainder)
 		stage_timeout++;

 	timeout = stage_timeout;
 	WARN_ON_ONCE(timeout != stage_timeout);

 	return timeout;
 }

 static int kempld_wdt_set_timeout(struct watchdog_device *wdd,
 					unsigned int timeout)
 {
 	struct kempld_wdt_data *wdt_data = watchdog_get_drvdata(wdd);
 	struct kempld_wdt_stage *pretimeout_stage;
 	struct kempld_wdt_stage *timeout_stage;
 	int ret;

 	timeout_stage = &wdt_data->stage[STAGE_TIMEOUT];
 	pretimeout_stage = &wdt_data->stage[STAGE_PRETIMEOUT];

 	if (pretimeout_stage->mask && wdt_data->pretimeout > 0)
 		timeout = wdt_data->pretimeout;

 	ret = kempld_wdt_set_stage_action(wdt_data, timeout_stage,
 						ACTION_RESET);
 	if (ret)
 		return ret;
 	ret = kempld_wdt_set_stage_timeout(wdt_data, timeout_stage,
 						timeout);
 	if (ret)
 		return ret;

 	wdd->timeout = timeout;
 	return 0;
 }

 static int kempld_wdt_set_pretimeout(struct watchdog_device *wdd,
 					unsigned int pretimeout)
 {
 	struct kempld_wdt_data *wdt_data = watchdog_get_drvdata(wdd);
 	struct kempld_wdt_stage *pretimeout_stage;
 	u8 action = ACTION_NONE;
 	int ret;

 	pretimeout_stage = &wdt_data->stage[STAGE_PRETIMEOUT];

 	if (!pretimeout_stage->mask)
 		return -ENXIO;

 	if (pretimeout > wdd->timeout)
 		return -EINVAL;

 	if (pretimeout > 0)
 		action = ACTION_NMI;

 	ret = kempld_wdt_set_stage_action(wdt_data, pretimeout_stage,
 						action);
 	if (ret)
 		return ret;
 	ret = kempld_wdt_set_stage_timeout(wdt_data, pretimeout_stage,
 						wdd->timeout - pretimeout);
 	if (ret)
 		return ret;

 	wdt_data->pretimeout = pretimeout;
 	return 0;
 }

 static void kempld_wdt_update_timeouts(struct kempld_wdt_data *wdt_data)
 {
 	struct kempld_device_data *pld = wdt_data->pld;
 	struct kempld_wdt_stage *pretimeout_stage;
 	struct kempld_wdt_stage *timeout_stage;
 	unsigned int pretimeout, timeout;

 	pretimeout_stage = &wdt_data->stage[STAGE_PRETIMEOUT];
 	timeout_stage = &wdt_data->stage[STAGE_TIMEOUT];

 	kempld_get_mutex(pld);
 	pretimeout = kempld_wdt_get_timeout(wdt_data, pretimeout_stage);
 	timeout = kempld_wdt_get_timeout(wdt_data, timeout_stage);
 	kempld_release_mutex(pld);

 	if (pretimeout)
 		wdt_data->pretimeout = timeout;
 	else
 		wdt_data->pretimeout = 0;

 	wdt_data->wdd.timeout = pretimeout + timeout;
 }

 static int kempld_wdt_start(struct watchdog_device *wdd)
 {
 	struct kempld_wdt_data *wdt_data = watchdog_get_drvdata(wdd);
 	struct kempld_device_data *pld = wdt_data->pld;
 	u8 status;
 	int ret;

 	ret = kempld_wdt_set_timeout(wdd, wdd->timeout);
 	if (ret)
 		return ret;

 	kempld_get_mutex(pld);
 	status = kempld_read8(pld, KEMPLD_WDT_CFG);
 	status |= KEMPLD_WDT_CFG_ENABLE;
 	kempld_write8(pld, KEMPLD_WDT_CFG, status);
 	status = kempld_read8(pld, KEMPLD_WDT_CFG);
 	kempld_release_mutex(pld);

 	/* Check if the watchdog was enabled */
 	if (!(status & KEMPLD_WDT_CFG_ENABLE))
 		return -EACCES;

 	return 0;
 }

 static int kempld_wdt_stop(struct watchdog_device *wdd)
 {
 	struct kempld_wdt_data *wdt_data = watchdog_get_drvdata(wdd);
 	struct kempld_device_data *pld = wdt_data->pld;
 	u8 status;

 	kempld_get_mutex(pld);
 	status = kempld_read8(pld, KEMPLD_WDT_CFG);
 	status &= ~KEMPLD_WDT_CFG_ENABLE;
 	kempld_write8(pld, KEMPLD_WDT_CFG, status);
 	status = kempld_read8(pld, KEMPLD_WDT_CFG);
 	kempld_release_mutex(pld);

 	/* Check if the watchdog was disabled */
 	if (status & KEMPLD_WDT_CFG_ENABLE)
 		return -EACCES;

 	return 0;
 }

 static int kempld_wdt_keepalive(struct watchdog_device *wdd)
 {
 	struct kempld_wdt_data *wdt_data = watchdog_get_drvdata(wdd);
 	struct kempld_device_data *pld = wdt_data->pld;

 	kempld_get_mutex(pld);
 	kempld_write8(pld, KEMPLD_WDT_KICK, 'K');
 	kempld_release_mutex(pld);

 	return 0;
 }

 static long kempld_wdt_ioctl(struct watchdog_device *wdd, unsigned int cmd,
 				unsigned long arg)
 {
 	struct kempld_wdt_data *wdt_data = watchdog_get_drvdata(wdd);
 	void __user *argp = (void __user *)arg;
 	int ret = -ENOIOCTLCMD;
 	int __user *p = argp;
 	int new_value;

 	switch (cmd) {
 	case WDIOC_SETPRETIMEOUT:
 		if (get_user(new_value, p))
 			return -EFAULT;
 		ret = kempld_wdt_set_pretimeout(wdd, new_value);
 		if (ret)
 			return ret;
 		ret = kempld_wdt_keepalive(wdd);
 		break;
 	case WDIOC_GETPRETIMEOUT:
 		ret = put_user(wdt_data->pretimeout, (int *)arg);
 		break;
 	}

 	return ret;
 }

 static int kempld_wdt_probe_stages(struct watchdog_device *wdd)
 {
 	struct kempld_wdt_data *wdt_data = watchdog_get_drvdata(wdd);
 	struct kempld_device_data *pld = wdt_data->pld;
 	struct kempld_wdt_stage *pretimeout_stage;
 	struct kempld_wdt_stage *timeout_stage;
 	u8 index, data, data_orig;
 	u32 mask;
 	int i, j;

 	pretimeout_stage = &wdt_data->stage[STAGE_PRETIMEOUT];
 	timeout_stage = &wdt_data->stage[STAGE_TIMEOUT];

 	pretimeout_stage->mask = 0;
 	timeout_stage->mask = 0;

 	for (i = 0; i < 3; i++) {
 		index = KEMPLD_WDT_STAGE_TIMEOUT(i);
 		mask = 0;

 		kempld_get_mutex(pld);
 		/* Probe each byte individually. */
 		for (j = 0; j < 4; j++) {
 			data_orig = kempld_read8(pld, index + j);
 			kempld_write8(pld, index + j, 0x00);
 			data = kempld_read8(pld, index + j);
 			/* A failed write means this byte is reserved */
 			if (data != 0x00)
 				break;
 			kempld_write8(pld, index + j, data_orig);
 			mask |= 0xff << (j * 8);
 		}
 		kempld_release_mutex(pld);

 		/* Assign available stages to timeout and pretimeout */
 		if (!timeout_stage->mask) {
 			timeout_stage->mask = mask;
 			timeout_stage->id = i;
 		} else {
 			if (pld->feature_mask & KEMPLD_FEATURE_BIT_NMI) {
 				pretimeout_stage->mask = timeout_stage->mask;
 				timeout_stage->mask = mask;
 				pretimeout_stage->id = timeout_stage->id;
 				timeout_stage->id = i;
 			}
 			break;
 		}
 	}

 	if (!timeout_stage->mask)
 		return -ENODEV;

 	return 0;
 }

 static struct watchdog_info kempld_wdt_info = {
 	.identity	= "KEMPLD Watchdog",
 	.options	= WDIOF_SETTIMEOUT |
 			WDIOF_KEEPALIVEPING |
 			WDIOF_MAGICCLOSE |
 			WDIOF_PRETIMEOUT
 };

 static struct watchdog_ops kempld_wdt_ops = {
 	.owner		= THIS_MODULE,
 	.start		= kempld_wdt_start,
 	.stop		= kempld_wdt_stop,
 	.ping		= kempld_wdt_keepalive,
 	.set_timeout	= kempld_wdt_set_timeout,
 	.ioctl		= kempld_wdt_ioctl,
 };

 static int kempld_wdt_probe(struct platform_device *pdev)
 {
 	struct kempld_device_data *pld = dev_get_drvdata(pdev->dev.parent);
 	struct kempld_wdt_data *wdt_data;
 	struct device *dev = &pdev->dev;
 	struct watchdog_device *wdd;
 	u8 status;
 	int ret = 0;

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

 	wdt_data->pld = pld;
 	wdd = &wdt_data->wdd;
 	wdd->parent = dev;

 	kempld_get_mutex(pld);
 	status = kempld_read8(pld, KEMPLD_WDT_CFG);
 	kempld_release_mutex(pld);

 	/* Enable nowayout if watchdog is already locked */
 	if (status & (KEMPLD_WDT_CFG_ENABLE_LOCK |
 			KEMPLD_WDT_CFG_GLOBAL_LOCK)) {
 		if (!nowayout)
 			dev_warn(dev,
 				"Forcing nowayout - watchdog lock enabled!\n");
 		nowayout = true;
 	}

 	wdd->info = &kempld_wdt_info;
 	wdd->ops = &kempld_wdt_ops;

 	watchdog_set_drvdata(wdd, wdt_data);
 	watchdog_set_nowayout(wdd, nowayout);

 	ret = kempld_wdt_probe_stages(wdd);
 	if (ret)
 		return ret;

 	kempld_wdt_set_timeout(wdd, timeout);
 	kempld_wdt_set_pretimeout(wdd, pretimeout);

 	/* Check if watchdog is already enabled */
 	if (status & KEMPLD_WDT_CFG_ENABLE) {
 		/* Get current watchdog settings */
 		kempld_wdt_update_timeouts(wdt_data);
 		dev_info(dev, "Watchdog was already enabled\n");
 	}

 	platform_set_drvdata(pdev, wdt_data);
 	ret = watchdog_register_device(wdd);
 	if (ret)
 		return ret;

 	dev_info(dev, "Watchdog registered with %ds timeout\n", wdd->timeout);

 	return 0;
 }

 static void kempld_wdt_shutdown(struct platform_device *pdev)
 {
 	struct kempld_wdt_data *wdt_data = platform_get_drvdata(pdev);

 	kempld_wdt_stop(&wdt_data->wdd);
 }

 static int kempld_wdt_remove(struct platform_device *pdev)
 {
 	struct kempld_wdt_data *wdt_data = platform_get_drvdata(pdev);
 	struct watchdog_device *wdd = &wdt_data->wdd;
 	int ret = 0;

 	if (!nowayout)
 		ret = kempld_wdt_stop(wdd);
 	watchdog_unregister_device(wdd);

 	return ret;
 }

 #ifdef CONFIG_PM
 /* Disable watchdog if it is active during suspend */
 static int kempld_wdt_suspend(struct platform_device *pdev,
 				pm_message_t message)
 {
 	struct kempld_wdt_data *wdt_data = platform_get_drvdata(pdev);
 	struct kempld_device_data *pld = wdt_data->pld;
 	struct watchdog_device *wdd = &wdt_data->wdd;

 	kempld_get_mutex(pld);
 	wdt_data->pm_status_store = kempld_read8(pld, KEMPLD_WDT_CFG);
 	kempld_release_mutex(pld);

 	kempld_wdt_update_timeouts(wdt_data);

 	if (wdt_data->pm_status_store & KEMPLD_WDT_CFG_ENABLE)
 		return kempld_wdt_stop(wdd);

 	return 0;
 }

 /* Enable watchdog and configure it if necessary */
 static int kempld_wdt_resume(struct platform_device *pdev)
 {
 	struct kempld_wdt_data *wdt_data = platform_get_drvdata(pdev);
 	struct watchdog_device *wdd = &wdt_data->wdd;

 	/*
 	 * If watchdog was stopped before suspend be sure it gets disabled
 	 * again, for the case BIOS has enabled it during resume
 	 */
 	if (wdt_data->pm_status_store & KEMPLD_WDT_CFG_ENABLE)
 		return kempld_wdt_start(wdd);
 	else
 		return kempld_wdt_stop(wdd);
 }
 #else
 #define kempld_wdt_suspend	NULL
 #define kempld_wdt_resume	NULL
 #endif

 static struct platform_driver kempld_wdt_driver = {
 	.driver		= {
 		.name	= "kempld-wdt",
 		.owner	= THIS_MODULE,
 	},
 	.probe		= kempld_wdt_probe,
 	.remove		= kempld_wdt_remove,
 	.shutdown	= kempld_wdt_shutdown,
 	.suspend	= kempld_wdt_suspend,
 	.resume		= kempld_wdt_resume,
 };

 module_platform_driver(kempld_wdt_driver);

 MODULE_DESCRIPTION("KEM PLD Watchdog Driver");
 MODULE_AUTHOR("Michael Brunner <michael.brunner@kontron.com>");
 MODULE_LICENSE("GPL");
 MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);
	/*
	* Kontron PLD watchdog driver
	*
	* Copyright (c) 2010-2013 Kontron Europe GmbH
	* Author: Michael Brunner <michael.brunner@kontron.com>
	*
	* This program is free software; you can redistribute it and/or modify
	* it under the terms of the GNU General Public License 2 as published
	* by the Free Software Foundation.
	*
	* This program is distributed in the hope that it will be useful,
	* but WITHOUT ANY WARRANTY; without even the implied warranty of
	* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
	* GNU General Public License for more details.
	*
	* Note: From the PLD watchdog point of view timeout and pretimeout are
	* defined differently than in the kernel.
	* First the pretimeout stage runs out before the timeout stage gets
	* active.
	*
	* Kernel/API: P-----\| pretimeout
	* \|-----------------------T timeout
	* Watchdog: \|-----------------P pretimeout_stage
	* \|-----T timeout_stage
	*/

	#include <linux/module.h>
	#include <linux/moduleparam.h>
	#include <linux/miscdevice.h>
	#include <linux/uaccess.h>
	#include <linux/watchdog.h>
	#include <linux/platform_device.h>
	#include <linux/mfd/kempld.h>

	#define KEMPLD_WDT_STAGE_TIMEOUT(x) (0x1b + (x) * 4)
	#define KEMPLD_WDT_STAGE_CFG(x) (0x18 + (x))
	#define STAGE_CFG_GET_PRESCALER(x) (((x) & 0x30) >> 4)
	#define STAGE_CFG_SET_PRESCALER(x) (((x) & 0x3) << 4)
	#define STAGE_CFG_PRESCALER_MASK 0x30
	#define STAGE_CFG_ACTION_MASK 0x7
	#define STAGE_CFG_ASSERT (1 << 3)

	#define KEMPLD_WDT_MAX_STAGES 2
	#define KEMPLD_WDT_KICK 0x16
	#define KEMPLD_WDT_CFG 0x17
	#define KEMPLD_WDT_CFG_ENABLE 0x10
	#define KEMPLD_WDT_CFG_ENABLE_LOCK 0x8
	#define KEMPLD_WDT_CFG_GLOBAL_LOCK 0x80

	enum {
	ACTION_NONE = 0,
	ACTION_RESET,
	ACTION_NMI,
	ACTION_SMI,
	ACTION_SCI,
	ACTION_DELAY,
	};

	enum {
	STAGE_TIMEOUT = 0,
	STAGE_PRETIMEOUT,
	};

	enum {
	PRESCALER_21 = 0,
	PRESCALER_17,
	PRESCALER_12,
	};

	const u32 kempld_prescaler[] = {
	[PRESCALER_21] = (1 << 21) - 1,
	[PRESCALER_17] = (1 << 17) - 1,
	[PRESCALER_12] = (1 << 12) - 1,
	0,
	};

	struct kempld_wdt_stage {
	unsigned int id;
	u32 mask;
	};

	struct kempld_wdt_data {
	struct kempld_device_data *pld;
	struct watchdog_device wdd;
	unsigned int pretimeout;
	struct kempld_wdt_stage stage[KEMPLD_WDT_MAX_STAGES];
	#ifdef CONFIG_PM
	u8 pm_status_store;
	#endif
	};

	#define DEFAULT_TIMEOUT 30 /* seconds */
	#define DEFAULT_PRETIMEOUT 0

	static unsigned int timeout = DEFAULT_TIMEOUT;
	module_param(timeout, uint, 0);
	MODULE_PARM_DESC(timeout,
	"Watchdog timeout in seconds. (>=0, default="
	__MODULE_STRING(DEFAULT_TIMEOUT) ")");

	static unsigned int pretimeout = DEFAULT_PRETIMEOUT;
	module_param(pretimeout, uint, 0);
	MODULE_PARM_DESC(pretimeout,
	"Watchdog pretimeout in seconds. (>=0, default="
	__MODULE_STRING(DEFAULT_PRETIMEOUT) ")");

	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) ")");

	static int kempld_wdt_set_stage_action(struct kempld_wdt_data *wdt_data,
	struct kempld_wdt_stage *stage,
	u8 action)
	{
	struct kempld_device_data *pld = wdt_data->pld;
	u8 stage_cfg;

	if (!stage \|\| !stage->mask)
	return -EINVAL;

	kempld_get_mutex(pld);
	stage_cfg = kempld_read8(pld, KEMPLD_WDT_STAGE_CFG(stage->id));
	stage_cfg &= ~STAGE_CFG_ACTION_MASK;
	stage_cfg \|= (action & STAGE_CFG_ACTION_MASK);

	if (action == ACTION_RESET)
	stage_cfg \|= STAGE_CFG_ASSERT;
	else
	stage_cfg &= ~STAGE_CFG_ASSERT;

	kempld_write8(pld, KEMPLD_WDT_STAGE_CFG(stage->id), stage_cfg);
	kempld_release_mutex(pld);

	return 0;
	}

	static int kempld_wdt_set_stage_timeout(struct kempld_wdt_data *wdt_data,
	struct kempld_wdt_stage *stage,
	unsigned int timeout)
	{
	struct kempld_device_data *pld = wdt_data->pld;
	u32 prescaler = kempld_prescaler[PRESCALER_21];
	u64 stage_timeout64;
	u32 stage_timeout;
	u32 remainder;
	u8 stage_cfg;

	if (!stage)
	return -EINVAL;

	stage_timeout64 = (u64)timeout * pld->pld_clock;
	remainder = do_div(stage_timeout64, prescaler);
	if (remainder)
	stage_timeout64++;

	if (stage_timeout64 > stage->mask)
	return -EINVAL;

	stage_timeout = stage_timeout64 & stage->mask;

	kempld_get_mutex(pld);
	stage_cfg = kempld_read8(pld, KEMPLD_WDT_STAGE_CFG(stage->id));
	stage_cfg &= ~STAGE_CFG_PRESCALER_MASK;
	stage_cfg \|= STAGE_CFG_SET_PRESCALER(prescaler);
	kempld_write8(pld, KEMPLD_WDT_STAGE_CFG(stage->id), stage_cfg);
	kempld_write32(pld, KEMPLD_WDT_STAGE_TIMEOUT(stage->id),
	stage_timeout);
	kempld_release_mutex(pld);

	return 0;
	}

	/*
	* kempld_get_mutex must be called prior to calling this function.
	*/
	static unsigned int kempld_wdt_get_timeout(struct kempld_wdt_data *wdt_data,
	struct kempld_wdt_stage *stage)
	{
	struct kempld_device_data *pld = wdt_data->pld;
	unsigned int timeout;
	u64 stage_timeout;
	u32 prescaler;
	u32 remainder;
	u8 stage_cfg;

	if (!stage->mask)
	return 0;

	stage_cfg = kempld_read8(pld, KEMPLD_WDT_STAGE_CFG(stage->id));
	stage_timeout = kempld_read32(pld, KEMPLD_WDT_STAGE_TIMEOUT(stage->id));
	prescaler = kempld_prescaler[STAGE_CFG_GET_PRESCALER(stage_cfg)];

	stage_timeout = (stage_timeout & stage->mask) * prescaler;
	remainder = do_div(stage_timeout, pld->pld_clock);
	if (remainder)
	stage_timeout++;

	timeout = stage_timeout;
	WARN_ON_ONCE(timeout != stage_timeout);

	return timeout;
	}

	static int kempld_wdt_set_timeout(struct watchdog_device *wdd,
	unsigned int timeout)
	{
	struct kempld_wdt_data *wdt_data = watchdog_get_drvdata(wdd);
	struct kempld_wdt_stage *pretimeout_stage;
	struct kempld_wdt_stage *timeout_stage;
	int ret;

	timeout_stage = &wdt_data->stage[STAGE_TIMEOUT];
	pretimeout_stage = &wdt_data->stage[STAGE_PRETIMEOUT];

	if (pretimeout_stage->mask && wdt_data->pretimeout > 0)
	timeout = wdt_data->pretimeout;

	ret = kempld_wdt_set_stage_action(wdt_data, timeout_stage,
	ACTION_RESET);
	if (ret)
	return ret;
	ret = kempld_wdt_set_stage_timeout(wdt_data, timeout_stage,
	timeout);
	if (ret)
	return ret;

	wdd->timeout = timeout;
	return 0;
	}

	static int kempld_wdt_set_pretimeout(struct watchdog_device *wdd,
	unsigned int pretimeout)
	{
	struct kempld_wdt_data *wdt_data = watchdog_get_drvdata(wdd);
	struct kempld_wdt_stage *pretimeout_stage;
	u8 action = ACTION_NONE;
	int ret;

	pretimeout_stage = &wdt_data->stage[STAGE_PRETIMEOUT];

	if (!pretimeout_stage->mask)
	return -ENXIO;

	if (pretimeout > wdd->timeout)
	return -EINVAL;

	if (pretimeout > 0)
	action = ACTION_NMI;

	ret = kempld_wdt_set_stage_action(wdt_data, pretimeout_stage,
	action);
	if (ret)
	return ret;
	ret = kempld_wdt_set_stage_timeout(wdt_data, pretimeout_stage,
	wdd->timeout - pretimeout);
	if (ret)
	return ret;

	wdt_data->pretimeout = pretimeout;
	return 0;
	}

	static void kempld_wdt_update_timeouts(struct kempld_wdt_data *wdt_data)
	{
	struct kempld_device_data *pld = wdt_data->pld;
	struct kempld_wdt_stage *pretimeout_stage;
	struct kempld_wdt_stage *timeout_stage;
	unsigned int pretimeout, timeout;

	pretimeout_stage = &wdt_data->stage[STAGE_PRETIMEOUT];
	timeout_stage = &wdt_data->stage[STAGE_TIMEOUT];

	kempld_get_mutex(pld);
	pretimeout = kempld_wdt_get_timeout(wdt_data, pretimeout_stage);
	timeout = kempld_wdt_get_timeout(wdt_data, timeout_stage);
	kempld_release_mutex(pld);

	if (pretimeout)
	wdt_data->pretimeout = timeout;
	else
	wdt_data->pretimeout = 0;

	wdt_data->wdd.timeout = pretimeout + timeout;
	}

	static int kempld_wdt_start(struct watchdog_device *wdd)
	{
	struct kempld_wdt_data *wdt_data = watchdog_get_drvdata(wdd);
	struct kempld_device_data *pld = wdt_data->pld;
	u8 status;
	int ret;

	ret = kempld_wdt_set_timeout(wdd, wdd->timeout);
	if (ret)
	return ret;

	kempld_get_mutex(pld);
	status = kempld_read8(pld, KEMPLD_WDT_CFG);
	status \|= KEMPLD_WDT_CFG_ENABLE;
	kempld_write8(pld, KEMPLD_WDT_CFG, status);
	status = kempld_read8(pld, KEMPLD_WDT_CFG);
	kempld_release_mutex(pld);

	/* Check if the watchdog was enabled */
	if (!(status & KEMPLD_WDT_CFG_ENABLE))
	return -EACCES;

	return 0;
	}

	static int kempld_wdt_stop(struct watchdog_device *wdd)
	{
	struct kempld_wdt_data *wdt_data = watchdog_get_drvdata(wdd);
	struct kempld_device_data *pld = wdt_data->pld;
	u8 status;

	kempld_get_mutex(pld);
	status = kempld_read8(pld, KEMPLD_WDT_CFG);
	status &= ~KEMPLD_WDT_CFG_ENABLE;
	kempld_write8(pld, KEMPLD_WDT_CFG, status);
	status = kempld_read8(pld, KEMPLD_WDT_CFG);
	kempld_release_mutex(pld);

	/* Check if the watchdog was disabled */
	if (status & KEMPLD_WDT_CFG_ENABLE)
	return -EACCES;

	return 0;
	}

	static int kempld_wdt_keepalive(struct watchdog_device *wdd)
	{
	struct kempld_wdt_data *wdt_data = watchdog_get_drvdata(wdd);
	struct kempld_device_data *pld = wdt_data->pld;

	kempld_get_mutex(pld);
	kempld_write8(pld, KEMPLD_WDT_KICK, 'K');
	kempld_release_mutex(pld);

	return 0;
	}

	static long kempld_wdt_ioctl(struct watchdog_device *wdd, unsigned int cmd,
	unsigned long arg)
	{
	struct kempld_wdt_data *wdt_data = watchdog_get_drvdata(wdd);
	void __user argp = (void __user )arg;
	int ret = -ENOIOCTLCMD;
	int __user *p = argp;
	int new_value;

	switch (cmd) {
	case WDIOC_SETPRETIMEOUT:
	if (get_user(new_value, p))
	return -EFAULT;
	ret = kempld_wdt_set_pretimeout(wdd, new_value);
	if (ret)
	return ret;
	ret = kempld_wdt_keepalive(wdd);
	break;
	case WDIOC_GETPRETIMEOUT:
	ret = put_user(wdt_data->pretimeout, (int *)arg);
	break;
	}

	return ret;
	}

	static int kempld_wdt_probe_stages(struct watchdog_device *wdd)
	{
	struct kempld_wdt_data *wdt_data = watchdog_get_drvdata(wdd);
	struct kempld_device_data *pld = wdt_data->pld;
	struct kempld_wdt_stage *pretimeout_stage;
	struct kempld_wdt_stage *timeout_stage;
	u8 index, data, data_orig;
	u32 mask;
	int i, j;

	pretimeout_stage = &wdt_data->stage[STAGE_PRETIMEOUT];
	timeout_stage = &wdt_data->stage[STAGE_TIMEOUT];

	pretimeout_stage->mask = 0;
	timeout_stage->mask = 0;

	for (i = 0; i < 3; i++) {
	index = KEMPLD_WDT_STAGE_TIMEOUT(i);
	mask = 0;

	kempld_get_mutex(pld);
	/* Probe each byte individually. */
	for (j = 0; j < 4; j++) {
	data_orig = kempld_read8(pld, index + j);
	kempld_write8(pld, index + j, 0x00);
	data = kempld_read8(pld, index + j);
	/* A failed write means this byte is reserved */
	if (data != 0x00)
	break;
	kempld_write8(pld, index + j, data_orig);
	mask \|= 0xff << (j * 8);
	}
	kempld_release_mutex(pld);

	/* Assign available stages to timeout and pretimeout */
	if (!timeout_stage->mask) {
	timeout_stage->mask = mask;
	timeout_stage->id = i;
	} else {
	if (pld->feature_mask & KEMPLD_FEATURE_BIT_NMI) {
	pretimeout_stage->mask = timeout_stage->mask;
	timeout_stage->mask = mask;
	pretimeout_stage->id = timeout_stage->id;
	timeout_stage->id = i;
	}
	break;
	}
	}

	if (!timeout_stage->mask)
	return -ENODEV;

	return 0;
	}

	static struct watchdog_info kempld_wdt_info = {
	.identity = "KEMPLD Watchdog",
	.options = WDIOF_SETTIMEOUT \|
	WDIOF_KEEPALIVEPING \|
	WDIOF_MAGICCLOSE \|
	WDIOF_PRETIMEOUT
	};

	static struct watchdog_ops kempld_wdt_ops = {
	.owner = THIS_MODULE,
	.start = kempld_wdt_start,
	.stop = kempld_wdt_stop,
	.ping = kempld_wdt_keepalive,
	.set_timeout = kempld_wdt_set_timeout,
	.ioctl = kempld_wdt_ioctl,
	};

	static int kempld_wdt_probe(struct platform_device *pdev)
	{
	struct kempld_device_data *pld = dev_get_drvdata(pdev->dev.parent);
	struct kempld_wdt_data *wdt_data;
	struct device *dev = &pdev->dev;
	struct watchdog_device *wdd;
	u8 status;
	int ret = 0;

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

	wdt_data->pld = pld;
	wdd = &wdt_data->wdd;
	wdd->parent = dev;

	kempld_get_mutex(pld);
	status = kempld_read8(pld, KEMPLD_WDT_CFG);
	kempld_release_mutex(pld);

	/* Enable nowayout if watchdog is already locked */
	if (status & (KEMPLD_WDT_CFG_ENABLE_LOCK \|
	KEMPLD_WDT_CFG_GLOBAL_LOCK)) {
	if (!nowayout)
	dev_warn(dev,
	"Forcing nowayout - watchdog lock enabled!\n");
	nowayout = true;
	}

	wdd->info = &kempld_wdt_info;
	wdd->ops = &kempld_wdt_ops;

	watchdog_set_drvdata(wdd, wdt_data);
	watchdog_set_nowayout(wdd, nowayout);

	ret = kempld_wdt_probe_stages(wdd);
	if (ret)
	return ret;

	kempld_wdt_set_timeout(wdd, timeout);
	kempld_wdt_set_pretimeout(wdd, pretimeout);

	/* Check if watchdog is already enabled */
	if (status & KEMPLD_WDT_CFG_ENABLE) {
	/* Get current watchdog settings */
	kempld_wdt_update_timeouts(wdt_data);
	dev_info(dev, "Watchdog was already enabled\n");
	}

	platform_set_drvdata(pdev, wdt_data);
	ret = watchdog_register_device(wdd);
	if (ret)
	return ret;

	dev_info(dev, "Watchdog registered with %ds timeout\n", wdd->timeout);

	return 0;
	}

	static void kempld_wdt_shutdown(struct platform_device *pdev)
	{
	struct kempld_wdt_data *wdt_data = platform_get_drvdata(pdev);

	kempld_wdt_stop(&wdt_data->wdd);
	}

	static int kempld_wdt_remove(struct platform_device *pdev)
	{
	struct kempld_wdt_data *wdt_data = platform_get_drvdata(pdev);
	struct watchdog_device *wdd = &wdt_data->wdd;
	int ret = 0;

	if (!nowayout)
	ret = kempld_wdt_stop(wdd);
	watchdog_unregister_device(wdd);

	return ret;
	}

	#ifdef CONFIG_PM
	/* Disable watchdog if it is active during suspend */
	static int kempld_wdt_suspend(struct platform_device *pdev,
	pm_message_t message)
	{
	struct kempld_wdt_data *wdt_data = platform_get_drvdata(pdev);
	struct kempld_device_data *pld = wdt_data->pld;
	struct watchdog_device *wdd = &wdt_data->wdd;

	kempld_get_mutex(pld);
	wdt_data->pm_status_store = kempld_read8(pld, KEMPLD_WDT_CFG);
	kempld_release_mutex(pld);

	kempld_wdt_update_timeouts(wdt_data);

	if (wdt_data->pm_status_store & KEMPLD_WDT_CFG_ENABLE)
	return kempld_wdt_stop(wdd);

	return 0;
	}

	/* Enable watchdog and configure it if necessary */
	static int kempld_wdt_resume(struct platform_device *pdev)
	{
	struct kempld_wdt_data *wdt_data = platform_get_drvdata(pdev);
	struct watchdog_device *wdd = &wdt_data->wdd;

	/*
	* If watchdog was stopped before suspend be sure it gets disabled
	* again, for the case BIOS has enabled it during resume
	*/
	if (wdt_data->pm_status_store & KEMPLD_WDT_CFG_ENABLE)
	return kempld_wdt_start(wdd);
	else
	return kempld_wdt_stop(wdd);
	}
	#else
	#define kempld_wdt_suspend NULL
	#define kempld_wdt_resume NULL
	#endif

	static struct platform_driver kempld_wdt_driver = {
	.driver = {
	.name = "kempld-wdt",
	.owner = THIS_MODULE,
	},
	.probe = kempld_wdt_probe,
	.remove = kempld_wdt_remove,
	.shutdown = kempld_wdt_shutdown,
	.suspend = kempld_wdt_suspend,
	.resume = kempld_wdt_resume,
	};

	module_platform_driver(kempld_wdt_driver);

	MODULE_DESCRIPTION("KEM PLD Watchdog Driver");
	MODULE_AUTHOR("Michael Brunner <michael.brunner@kontron.com>");
	MODULE_LICENSE("GPL");
	MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);