drivers/watchdog/imx2_wdt.c - third_party/linux - Git at Google

 // SPDX-License-Identifier: GPL-2.0
 /*
  * Watchdog driver for IMX2 and later processors
  *
  *  Copyright (C) 2010 Wolfram Sang, Pengutronix e.K. <kernel@pengutronix.de>
  *  Copyright (C) 2014 Freescale Semiconductor, Inc.
  *
  * some parts adapted by similar drivers from Darius Augulis and Vladimir
  * Zapolskiy, additional improvements by Wim Van Sebroeck.
  *
  * NOTE: MX1 has a slightly different Watchdog than MX2 and later:
  *
  *			MX1:		MX2+:
  *			----		-----
  * Registers:		32-bit		16-bit
  * Stopable timer:	Yes		No
  * Need to enable clk:	No		Yes
  * Halt on suspend:	Manual		Can be automatic
  */

 #include <linux/clk.h>
 #include <linux/delay.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/of.h>
 #include <linux/platform_device.h>
 #include <linux/regmap.h>
 #include <linux/watchdog.h>

 #define DRIVER_NAME "imx2-wdt"

 #define IMX2_WDT_WCR		0x00		/* Control Register */
 #define IMX2_WDT_WCR_WT		(0xFF << 8)	/* -> Watchdog Timeout Field */
 #define IMX2_WDT_WCR_WDW	BIT(7)		/* -> Watchdog disable for WAIT */
 #define IMX2_WDT_WCR_WDA	BIT(5)		/* -> External Reset WDOG_B */
 #define IMX2_WDT_WCR_SRS	BIT(4)		/* -> Software Reset Signal */
 #define IMX2_WDT_WCR_WRE	BIT(3)		/* -> WDOG Reset Enable */
 #define IMX2_WDT_WCR_WDE	BIT(2)		/* -> Watchdog Enable */
 #define IMX2_WDT_WCR_WDZST	BIT(0)		/* -> Watchdog timer Suspend */

 #define IMX2_WDT_WSR		0x02		/* Service Register */
 #define IMX2_WDT_SEQ1		0x5555		/* -> service sequence 1 */
 #define IMX2_WDT_SEQ2		0xAAAA		/* -> service sequence 2 */

 #define IMX2_WDT_WRSR		0x04		/* Reset Status Register */
 #define IMX2_WDT_WRSR_TOUT	BIT(1)		/* -> Reset due to Timeout */

 #define IMX2_WDT_WICR		0x06		/* Interrupt Control Register */
 #define IMX2_WDT_WICR_WIE	BIT(15)		/* -> Interrupt Enable */
 #define IMX2_WDT_WICR_WTIS	BIT(14)		/* -> Interrupt Status */
 #define IMX2_WDT_WICR_WICT	0xFF		/* -> Interrupt Count Timeout */

 #define IMX2_WDT_WMCR		0x08		/* Misc Register */

 #define IMX2_WDT_MAX_TIME	128U
 #define IMX2_WDT_DEFAULT_TIME	60		/* in seconds */

 #define WDOG_SEC_TO_COUNT(s)	((s * 2 - 1) << 8)

 struct imx2_wdt_data {
 	bool wdw_supported;
 };

 struct imx2_wdt_device {
 	struct clk *clk;
 	struct regmap *regmap;
 	struct watchdog_device wdog;
 	const struct imx2_wdt_data *data;
 	bool ext_reset;
 	bool clk_is_on;
 	bool no_ping;
 	bool sleep_wait;
 };

 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 unsigned timeout;
 module_param(timeout, uint, 0);
 MODULE_PARM_DESC(timeout, "Watchdog timeout in seconds (default="
 				__MODULE_STRING(IMX2_WDT_DEFAULT_TIME) ")");

 static const struct watchdog_info imx2_wdt_info = {
 	.identity = "imx2+ watchdog",
 	.options = WDIOF_KEEPALIVEPING | WDIOF_SETTIMEOUT | WDIOF_MAGICCLOSE,
 };

 static const struct watchdog_info imx2_wdt_pretimeout_info = {
 	.identity = "imx2+ watchdog",
 	.options = WDIOF_KEEPALIVEPING | WDIOF_SETTIMEOUT | WDIOF_MAGICCLOSE |
 		   WDIOF_PRETIMEOUT,
 };

 static int imx2_wdt_restart(struct watchdog_device *wdog, unsigned long action,
 			    void *data)
 {
 	struct imx2_wdt_device *wdev = watchdog_get_drvdata(wdog);
 	unsigned int wcr_enable = IMX2_WDT_WCR_WDE;

 	/* Use internal reset or external - not both */
 	if (wdev->ext_reset)
 		wcr_enable |= IMX2_WDT_WCR_SRS; /* do not assert int reset */
 	else
 		wcr_enable |= IMX2_WDT_WCR_WDA; /* do not assert ext-reset */

 	/* Assert SRS signal */
 	regmap_write(wdev->regmap, IMX2_WDT_WCR, wcr_enable);
 	/*
 	 * Due to imx6q errata ERR004346 (WDOG: WDOG SRS bit requires to be
 	 * written twice), we add another two writes to ensure there must be at
 	 * least two writes happen in the same one 32kHz clock period.  We save
 	 * the target check here, since the writes shouldn't be a huge burden
 	 * for other platforms.
 	 */
 	regmap_write(wdev->regmap, IMX2_WDT_WCR, wcr_enable);
 	regmap_write(wdev->regmap, IMX2_WDT_WCR, wcr_enable);

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

 	return 0;
 }

 static inline void imx2_wdt_setup(struct watchdog_device *wdog)
 {
 	struct imx2_wdt_device *wdev = watchdog_get_drvdata(wdog);
 	u32 val;

 	regmap_read(wdev->regmap, IMX2_WDT_WCR, &val);

 	/* Suspend timer in low power mode, write once-only */
 	val |= IMX2_WDT_WCR_WDZST;
 	/* Suspend timer in low power WAIT mode, write once-only */
 	if (wdev->sleep_wait)
 		val |= IMX2_WDT_WCR_WDW;
 	/* Strip the old watchdog Time-Out value */
 	val &= ~IMX2_WDT_WCR_WT;
 	/* Generate internal chip-level reset if WDOG times out */
 	if (!wdev->ext_reset)
 		val &= ~IMX2_WDT_WCR_WRE;
 	/* Or if external-reset assert WDOG_B reset only on time-out */
 	else
 		val |= IMX2_WDT_WCR_WRE;
 	/* Keep Watchdog Disabled */
 	val &= ~IMX2_WDT_WCR_WDE;
 	/* Set the watchdog's Time-Out value */
 	val |= WDOG_SEC_TO_COUNT(wdog->timeout);

 	regmap_write(wdev->regmap, IMX2_WDT_WCR, val);

 	/* enable the watchdog */
 	val |= IMX2_WDT_WCR_WDE;
 	regmap_write(wdev->regmap, IMX2_WDT_WCR, val);
 }

 static inline bool imx2_wdt_is_running(struct imx2_wdt_device *wdev)
 {
 	u32 val;

 	regmap_read(wdev->regmap, IMX2_WDT_WCR, &val);

 	return val & IMX2_WDT_WCR_WDE;
 }

 static int imx2_wdt_ping(struct watchdog_device *wdog)
 {
 	struct imx2_wdt_device *wdev = watchdog_get_drvdata(wdog);

 	if (!wdev->clk_is_on)
 		return 0;

 	regmap_write(wdev->regmap, IMX2_WDT_WSR, IMX2_WDT_SEQ1);
 	regmap_write(wdev->regmap, IMX2_WDT_WSR, IMX2_WDT_SEQ2);
 	return 0;
 }

 static void __imx2_wdt_set_timeout(struct watchdog_device *wdog,
 				   unsigned int new_timeout)
 {
 	struct imx2_wdt_device *wdev = watchdog_get_drvdata(wdog);

 	regmap_update_bits(wdev->regmap, IMX2_WDT_WCR, IMX2_WDT_WCR_WT,
 			   WDOG_SEC_TO_COUNT(new_timeout));
 }

 static int imx2_wdt_set_timeout(struct watchdog_device *wdog,
 				unsigned int new_timeout)
 {
 	unsigned int actual;

 	actual = min(new_timeout, IMX2_WDT_MAX_TIME);
 	__imx2_wdt_set_timeout(wdog, actual);
 	wdog->timeout = new_timeout;
 	return 0;
 }

 static int imx2_wdt_set_pretimeout(struct watchdog_device *wdog,
 				   unsigned int new_pretimeout)
 {
 	struct imx2_wdt_device *wdev = watchdog_get_drvdata(wdog);

 	if (new_pretimeout >= IMX2_WDT_MAX_TIME)
 		return -EINVAL;

 	wdog->pretimeout = new_pretimeout;

 	regmap_update_bits(wdev->regmap, IMX2_WDT_WICR,
 			   IMX2_WDT_WICR_WIE | IMX2_WDT_WICR_WICT,
 			   IMX2_WDT_WICR_WIE | (new_pretimeout << 1));
 	return 0;
 }

 static irqreturn_t imx2_wdt_isr(int irq, void *wdog_arg)
 {
 	struct watchdog_device *wdog = wdog_arg;
 	struct imx2_wdt_device *wdev = watchdog_get_drvdata(wdog);

 	regmap_write_bits(wdev->regmap, IMX2_WDT_WICR,
 			  IMX2_WDT_WICR_WTIS, IMX2_WDT_WICR_WTIS);

 	watchdog_notify_pretimeout(wdog);

 	return IRQ_HANDLED;
 }

 static int imx2_wdt_start(struct watchdog_device *wdog)
 {
 	struct imx2_wdt_device *wdev = watchdog_get_drvdata(wdog);

 	if (imx2_wdt_is_running(wdev))
 		imx2_wdt_set_timeout(wdog, wdog->timeout);
 	else
 		imx2_wdt_setup(wdog);

 	set_bit(WDOG_HW_RUNNING, &wdog->status);

 	return imx2_wdt_ping(wdog);
 }

 static const struct watchdog_ops imx2_wdt_ops = {
 	.owner = THIS_MODULE,
 	.start = imx2_wdt_start,
 	.ping = imx2_wdt_ping,
 	.set_timeout = imx2_wdt_set_timeout,
 	.set_pretimeout = imx2_wdt_set_pretimeout,
 	.restart = imx2_wdt_restart,
 };

 static const struct regmap_config imx2_wdt_regmap_config = {
 	.reg_bits = 16,
 	.reg_stride = 2,
 	.val_bits = 16,
 	.max_register = 0x8,
 };

 static void imx2_wdt_action(void *data)
 {
 	clk_disable_unprepare(data);
 }

 static int __init imx2_wdt_probe(struct platform_device *pdev)
 {
 	struct device *dev = &pdev->dev;
 	struct imx2_wdt_device *wdev;
 	struct watchdog_device *wdog;
 	void __iomem *base;
 	int ret;
 	u32 val;

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

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

 	wdev->regmap = devm_regmap_init_mmio_clk(dev, NULL, base,
 						 &imx2_wdt_regmap_config);
 	if (IS_ERR(wdev->regmap)) {
 		dev_err(dev, "regmap init failed\n");
 		return PTR_ERR(wdev->regmap);
 	}

 	wdev->clk = devm_clk_get(dev, NULL);
 	if (IS_ERR(wdev->clk)) {
 		dev_err(dev, "can't get Watchdog clock\n");
 		return PTR_ERR(wdev->clk);
 	}

 	wdog			= &wdev->wdog;
 	wdog->info		= &imx2_wdt_info;
 	wdog->ops		= &imx2_wdt_ops;
 	wdog->min_timeout	= 1;
 	wdog->timeout		= IMX2_WDT_DEFAULT_TIME;
 	wdog->max_hw_heartbeat_ms = IMX2_WDT_MAX_TIME * 1000;
 	wdog->parent		= dev;

 	wdev->data = of_device_get_match_data(dev);

 	ret = platform_get_irq(pdev, 0);
 	if (ret > 0)
 		if (!devm_request_irq(dev, ret, imx2_wdt_isr, 0,
 				      dev_name(dev), wdog))
 			wdog->info = &imx2_wdt_pretimeout_info;

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

 	ret = devm_add_action_or_reset(dev, imx2_wdt_action, wdev->clk);
 	if (ret)
 		return ret;

 	wdev->clk_is_on = true;

 	regmap_read(wdev->regmap, IMX2_WDT_WRSR, &val);
 	wdog->bootstatus = val & IMX2_WDT_WRSR_TOUT ? WDIOF_CARDRESET : 0;

 	wdev->ext_reset = of_property_read_bool(dev->of_node,
 						"fsl,ext-reset-output");

 	if (of_property_read_bool(dev->of_node, "fsl,suspend-in-wait")) {
 		if (!wdev->data->wdw_supported) {
 			dev_err(dev, "suspend-in-wait not supported\n");
 			return -EINVAL;
 		}
 		wdev->sleep_wait = true;
 	}

 	/*
 	 * The i.MX7D doesn't support low power mode, so we need to ping the watchdog
 	 * during suspend. Interaction with "fsl,suspend-in-wait" is unknown!
 	 */
 	wdev->no_ping = !of_device_is_compatible(dev->of_node, "fsl,imx7d-wdt");
 	platform_set_drvdata(pdev, wdog);
 	watchdog_set_drvdata(wdog, wdev);
 	watchdog_set_nowayout(wdog, nowayout);
 	watchdog_set_restart_priority(wdog, 128);
 	watchdog_init_timeout(wdog, timeout, dev);
 	if (wdev->no_ping)
 		watchdog_stop_ping_on_suspend(wdog);

 	if (imx2_wdt_is_running(wdev)) {
 		imx2_wdt_set_timeout(wdog, wdog->timeout);
 		set_bit(WDOG_HW_RUNNING, &wdog->status);
 	}

 	/*
 	 * Disable the watchdog power down counter at boot. Otherwise the power
 	 * down counter will pull down the #WDOG interrupt line for one clock
 	 * cycle.
 	 */
 	regmap_write(wdev->regmap, IMX2_WDT_WMCR, 0);

 	return devm_watchdog_register_device(dev, wdog);
 }

 static void imx2_wdt_shutdown(struct platform_device *pdev)
 {
 	struct watchdog_device *wdog = platform_get_drvdata(pdev);
 	struct imx2_wdt_device *wdev = watchdog_get_drvdata(wdog);

 	if (imx2_wdt_is_running(wdev)) {
 		/*
 		 * We are running, configure max timeout before reboot
 		 * will take place.
 		 */
 		imx2_wdt_set_timeout(wdog, IMX2_WDT_MAX_TIME);
 		imx2_wdt_ping(wdog);
 		dev_crit(&pdev->dev, "Device shutdown.\n");
 	}
 }

 /* Disable watchdog if it is active or non-active but still running */
 static int __maybe_unused imx2_wdt_suspend(struct device *dev)
 {
 	struct watchdog_device *wdog = dev_get_drvdata(dev);
 	struct imx2_wdt_device *wdev = watchdog_get_drvdata(wdog);

 	/* The watchdog IP block is running */
 	if (imx2_wdt_is_running(wdev)) {
 		/*
 		 * Don't update wdog->timeout, we'll restore the current value
 		 * during resume.
 		 */
 		__imx2_wdt_set_timeout(wdog, IMX2_WDT_MAX_TIME);
 		imx2_wdt_ping(wdog);
 	}

 	if (wdev->no_ping) {
 		clk_disable_unprepare(wdev->clk);

 		wdev->clk_is_on = false;
 	}

 	return 0;
 }

 /* Enable watchdog and configure it if necessary */
 static int __maybe_unused imx2_wdt_resume(struct device *dev)
 {
 	struct watchdog_device *wdog = dev_get_drvdata(dev);
 	struct imx2_wdt_device *wdev = watchdog_get_drvdata(wdog);
 	int ret;

 	if (wdev->no_ping) {
 		ret = clk_prepare_enable(wdev->clk);

 		if (ret)
 			return ret;

 		wdev->clk_is_on = true;
 	}

 	if (watchdog_active(wdog) && !imx2_wdt_is_running(wdev)) {
 		/*
 		 * If the watchdog is still active and resumes
 		 * from deep sleep state, need to restart the
 		 * watchdog again.
 		 */
 		imx2_wdt_setup(wdog);
 	}
 	if (imx2_wdt_is_running(wdev)) {
 		imx2_wdt_set_timeout(wdog, wdog->timeout);
 		imx2_wdt_ping(wdog);
 	}

 	return 0;
 }

 static SIMPLE_DEV_PM_OPS(imx2_wdt_pm_ops, imx2_wdt_suspend,
 			 imx2_wdt_resume);

 static struct imx2_wdt_data imx_wdt = {
 	.wdw_supported = true,
 };

 static struct imx2_wdt_data imx_wdt_legacy = {
 	.wdw_supported = false,
 };

 static const struct of_device_id imx2_wdt_dt_ids[] = {
 	{ .compatible = "fsl,imx21-wdt", .data = &imx_wdt_legacy },
 	{ .compatible = "fsl,imx25-wdt", .data = &imx_wdt },
 	{ .compatible = "fsl,imx27-wdt", .data = &imx_wdt_legacy },
 	{ .compatible = "fsl,imx31-wdt", .data = &imx_wdt_legacy },
 	{ .compatible = "fsl,imx35-wdt", .data = &imx_wdt },
 	{ .compatible = "fsl,imx50-wdt", .data = &imx_wdt },
 	{ .compatible = "fsl,imx51-wdt", .data = &imx_wdt },
 	{ .compatible = "fsl,imx53-wdt", .data = &imx_wdt },
 	{ .compatible = "fsl,imx6q-wdt", .data = &imx_wdt },
 	{ .compatible = "fsl,imx6sl-wdt", .data = &imx_wdt },
 	{ .compatible = "fsl,imx6sll-wdt", .data = &imx_wdt },
 	{ .compatible = "fsl,imx6sx-wdt", .data = &imx_wdt },
 	{ .compatible = "fsl,imx6ul-wdt", .data = &imx_wdt },
 	{ .compatible = "fsl,imx7d-wdt", .data = &imx_wdt },
 	{ .compatible = "fsl,imx8mm-wdt", .data = &imx_wdt },
 	{ .compatible = "fsl,imx8mn-wdt", .data = &imx_wdt },
 	{ .compatible = "fsl,imx8mp-wdt", .data = &imx_wdt },
 	{ .compatible = "fsl,imx8mq-wdt", .data = &imx_wdt },
 	{ .compatible = "fsl,ls1012a-wdt", .data = &imx_wdt_legacy },
 	{ .compatible = "fsl,ls1043a-wdt", .data = &imx_wdt_legacy },
 	{ .compatible = "fsl,vf610-wdt", .data = &imx_wdt },
 	{ /* sentinel */ }
 };
 MODULE_DEVICE_TABLE(of, imx2_wdt_dt_ids);

 static struct platform_driver imx2_wdt_driver = {
 	.shutdown	= imx2_wdt_shutdown,
 	.driver		= {
 		.name	= DRIVER_NAME,
 		.pm     = &imx2_wdt_pm_ops,
 		.of_match_table = imx2_wdt_dt_ids,
 	},
 };

 module_platform_driver_probe(imx2_wdt_driver, imx2_wdt_probe);

 MODULE_AUTHOR("Wolfram Sang");
 MODULE_DESCRIPTION("Watchdog driver for IMX2 and later");
 MODULE_LICENSE("GPL v2");
 MODULE_ALIAS("platform:" DRIVER_NAME);
	// SPDX-License-Identifier: GPL-2.0
	/*
	* Watchdog driver for IMX2 and later processors
	*
	* Copyright (C) 2010 Wolfram Sang, Pengutronix e.K. <kernel@pengutronix.de>
	* Copyright (C) 2014 Freescale Semiconductor, Inc.
	*
	* some parts adapted by similar drivers from Darius Augulis and Vladimir
	* Zapolskiy, additional improvements by Wim Van Sebroeck.
	*
	* NOTE: MX1 has a slightly different Watchdog than MX2 and later:
	*
	* MX1: MX2+:
	* ---- -----
	* Registers: 32-bit 16-bit
	* Stopable timer: Yes No
	* Need to enable clk: No Yes
	* Halt on suspend: Manual Can be automatic
	*/

	#include <linux/clk.h>
	#include <linux/delay.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/of.h>
	#include <linux/platform_device.h>
	#include <linux/regmap.h>
	#include <linux/watchdog.h>

	#define DRIVER_NAME "imx2-wdt"

	#define IMX2_WDT_WCR 0x00 /* Control Register */
	#define IMX2_WDT_WCR_WT (0xFF << 8) /* -> Watchdog Timeout Field */
	#define IMX2_WDT_WCR_WDW BIT(7) /* -> Watchdog disable for WAIT */
	#define IMX2_WDT_WCR_WDA BIT(5) /* -> External Reset WDOG_B */
	#define IMX2_WDT_WCR_SRS BIT(4) /* -> Software Reset Signal */
	#define IMX2_WDT_WCR_WRE BIT(3) /* -> WDOG Reset Enable */
	#define IMX2_WDT_WCR_WDE BIT(2) /* -> Watchdog Enable */
	#define IMX2_WDT_WCR_WDZST BIT(0) /* -> Watchdog timer Suspend */

	#define IMX2_WDT_WSR 0x02 /* Service Register */
	#define IMX2_WDT_SEQ1 0x5555 /* -> service sequence 1 */
	#define IMX2_WDT_SEQ2 0xAAAA /* -> service sequence 2 */

	#define IMX2_WDT_WRSR 0x04 /* Reset Status Register */
	#define IMX2_WDT_WRSR_TOUT BIT(1) /* -> Reset due to Timeout */

	#define IMX2_WDT_WICR 0x06 /* Interrupt Control Register */
	#define IMX2_WDT_WICR_WIE BIT(15) /* -> Interrupt Enable */
	#define IMX2_WDT_WICR_WTIS BIT(14) /* -> Interrupt Status */
	#define IMX2_WDT_WICR_WICT 0xFF /* -> Interrupt Count Timeout */

	#define IMX2_WDT_WMCR 0x08 /* Misc Register */

	#define IMX2_WDT_MAX_TIME 128U
	#define IMX2_WDT_DEFAULT_TIME 60 /* in seconds */

	#define WDOG_SEC_TO_COUNT(s) ((s * 2 - 1) << 8)

	struct imx2_wdt_data {
	bool wdw_supported;
	};

	struct imx2_wdt_device {
	struct clk *clk;
	struct regmap *regmap;
	struct watchdog_device wdog;
	const struct imx2_wdt_data *data;
	bool ext_reset;
	bool clk_is_on;
	bool no_ping;
	bool sleep_wait;
	};

	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 unsigned timeout;
	module_param(timeout, uint, 0);
	MODULE_PARM_DESC(timeout, "Watchdog timeout in seconds (default="
	__MODULE_STRING(IMX2_WDT_DEFAULT_TIME) ")");

	static const struct watchdog_info imx2_wdt_info = {
	.identity = "imx2+ watchdog",
	.options = WDIOF_KEEPALIVEPING \| WDIOF_SETTIMEOUT \| WDIOF_MAGICCLOSE,
	};

	static const struct watchdog_info imx2_wdt_pretimeout_info = {
	.identity = "imx2+ watchdog",
	.options = WDIOF_KEEPALIVEPING \| WDIOF_SETTIMEOUT \| WDIOF_MAGICCLOSE \|
	WDIOF_PRETIMEOUT,
	};

	static int imx2_wdt_restart(struct watchdog_device *wdog, unsigned long action,
	void *data)
	{
	struct imx2_wdt_device *wdev = watchdog_get_drvdata(wdog);
	unsigned int wcr_enable = IMX2_WDT_WCR_WDE;

	/* Use internal reset or external - not both */
	if (wdev->ext_reset)
	wcr_enable \|= IMX2_WDT_WCR_SRS; /* do not assert int reset */
	else
	wcr_enable \|= IMX2_WDT_WCR_WDA; /* do not assert ext-reset */

	/* Assert SRS signal */
	regmap_write(wdev->regmap, IMX2_WDT_WCR, wcr_enable);
	/*
	* Due to imx6q errata ERR004346 (WDOG: WDOG SRS bit requires to be
	* written twice), we add another two writes to ensure there must be at
	* least two writes happen in the same one 32kHz clock period. We save
	* the target check here, since the writes shouldn't be a huge burden
	* for other platforms.
	*/
	regmap_write(wdev->regmap, IMX2_WDT_WCR, wcr_enable);
	regmap_write(wdev->regmap, IMX2_WDT_WCR, wcr_enable);

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

	return 0;
	}

	static inline void imx2_wdt_setup(struct watchdog_device *wdog)
	{
	struct imx2_wdt_device *wdev = watchdog_get_drvdata(wdog);
	u32 val;

	regmap_read(wdev->regmap, IMX2_WDT_WCR, &val);

	/* Suspend timer in low power mode, write once-only */
	val \|= IMX2_WDT_WCR_WDZST;
	/* Suspend timer in low power WAIT mode, write once-only */
	if (wdev->sleep_wait)
	val \|= IMX2_WDT_WCR_WDW;
	/* Strip the old watchdog Time-Out value */
	val &= ~IMX2_WDT_WCR_WT;
	/* Generate internal chip-level reset if WDOG times out */
	if (!wdev->ext_reset)
	val &= ~IMX2_WDT_WCR_WRE;
	/* Or if external-reset assert WDOG_B reset only on time-out */
	else
	val \|= IMX2_WDT_WCR_WRE;
	/* Keep Watchdog Disabled */
	val &= ~IMX2_WDT_WCR_WDE;
	/* Set the watchdog's Time-Out value */
	val \|= WDOG_SEC_TO_COUNT(wdog->timeout);

	regmap_write(wdev->regmap, IMX2_WDT_WCR, val);

	/* enable the watchdog */
	val \|= IMX2_WDT_WCR_WDE;
	regmap_write(wdev->regmap, IMX2_WDT_WCR, val);
	}

	static inline bool imx2_wdt_is_running(struct imx2_wdt_device *wdev)
	{
	u32 val;

	regmap_read(wdev->regmap, IMX2_WDT_WCR, &val);

	return val & IMX2_WDT_WCR_WDE;
	}

	static int imx2_wdt_ping(struct watchdog_device *wdog)
	{
	struct imx2_wdt_device *wdev = watchdog_get_drvdata(wdog);

	if (!wdev->clk_is_on)
	return 0;

	regmap_write(wdev->regmap, IMX2_WDT_WSR, IMX2_WDT_SEQ1);
	regmap_write(wdev->regmap, IMX2_WDT_WSR, IMX2_WDT_SEQ2);
	return 0;
	}

	static void __imx2_wdt_set_timeout(struct watchdog_device *wdog,
	unsigned int new_timeout)
	{
	struct imx2_wdt_device *wdev = watchdog_get_drvdata(wdog);

	regmap_update_bits(wdev->regmap, IMX2_WDT_WCR, IMX2_WDT_WCR_WT,
	WDOG_SEC_TO_COUNT(new_timeout));
	}

	static int imx2_wdt_set_timeout(struct watchdog_device *wdog,
	unsigned int new_timeout)
	{
	unsigned int actual;

	actual = min(new_timeout, IMX2_WDT_MAX_TIME);
	__imx2_wdt_set_timeout(wdog, actual);
	wdog->timeout = new_timeout;
	return 0;
	}

	static int imx2_wdt_set_pretimeout(struct watchdog_device *wdog,
	unsigned int new_pretimeout)
	{
	struct imx2_wdt_device *wdev = watchdog_get_drvdata(wdog);

	if (new_pretimeout >= IMX2_WDT_MAX_TIME)
	return -EINVAL;

	wdog->pretimeout = new_pretimeout;

	regmap_update_bits(wdev->regmap, IMX2_WDT_WICR,
	IMX2_WDT_WICR_WIE \| IMX2_WDT_WICR_WICT,
	IMX2_WDT_WICR_WIE \| (new_pretimeout << 1));
	return 0;
	}

	static irqreturn_t imx2_wdt_isr(int irq, void *wdog_arg)
	{
	struct watchdog_device *wdog = wdog_arg;
	struct imx2_wdt_device *wdev = watchdog_get_drvdata(wdog);

	regmap_write_bits(wdev->regmap, IMX2_WDT_WICR,
	IMX2_WDT_WICR_WTIS, IMX2_WDT_WICR_WTIS);

	watchdog_notify_pretimeout(wdog);

	return IRQ_HANDLED;
	}

	static int imx2_wdt_start(struct watchdog_device *wdog)
	{
	struct imx2_wdt_device *wdev = watchdog_get_drvdata(wdog);

	if (imx2_wdt_is_running(wdev))
	imx2_wdt_set_timeout(wdog, wdog->timeout);
	else
	imx2_wdt_setup(wdog);

	set_bit(WDOG_HW_RUNNING, &wdog->status);

	return imx2_wdt_ping(wdog);
	}

	static const struct watchdog_ops imx2_wdt_ops = {
	.owner = THIS_MODULE,
	.start = imx2_wdt_start,
	.ping = imx2_wdt_ping,
	.set_timeout = imx2_wdt_set_timeout,
	.set_pretimeout = imx2_wdt_set_pretimeout,
	.restart = imx2_wdt_restart,
	};

	static const struct regmap_config imx2_wdt_regmap_config = {
	.reg_bits = 16,
	.reg_stride = 2,
	.val_bits = 16,
	.max_register = 0x8,
	};

	static void imx2_wdt_action(void *data)
	{
	clk_disable_unprepare(data);
	}

	static int __init imx2_wdt_probe(struct platform_device *pdev)
	{
	struct device *dev = &pdev->dev;
	struct imx2_wdt_device *wdev;
	struct watchdog_device *wdog;
	void __iomem *base;
	int ret;
	u32 val;

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

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

	wdev->regmap = devm_regmap_init_mmio_clk(dev, NULL, base,
	&imx2_wdt_regmap_config);
	if (IS_ERR(wdev->regmap)) {
	dev_err(dev, "regmap init failed\n");
	return PTR_ERR(wdev->regmap);
	}

	wdev->clk = devm_clk_get(dev, NULL);
	if (IS_ERR(wdev->clk)) {
	dev_err(dev, "can't get Watchdog clock\n");
	return PTR_ERR(wdev->clk);
	}

	wdog = &wdev->wdog;
	wdog->info = &imx2_wdt_info;
	wdog->ops = &imx2_wdt_ops;
	wdog->min_timeout = 1;
	wdog->timeout = IMX2_WDT_DEFAULT_TIME;
	wdog->max_hw_heartbeat_ms = IMX2_WDT_MAX_TIME * 1000;
	wdog->parent = dev;

	wdev->data = of_device_get_match_data(dev);

	ret = platform_get_irq(pdev, 0);
	if (ret > 0)
	if (!devm_request_irq(dev, ret, imx2_wdt_isr, 0,
	dev_name(dev), wdog))
	wdog->info = &imx2_wdt_pretimeout_info;

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

	ret = devm_add_action_or_reset(dev, imx2_wdt_action, wdev->clk);
	if (ret)
	return ret;

	wdev->clk_is_on = true;

	regmap_read(wdev->regmap, IMX2_WDT_WRSR, &val);
	wdog->bootstatus = val & IMX2_WDT_WRSR_TOUT ? WDIOF_CARDRESET : 0;

	wdev->ext_reset = of_property_read_bool(dev->of_node,
	"fsl,ext-reset-output");

	if (of_property_read_bool(dev->of_node, "fsl,suspend-in-wait")) {
	if (!wdev->data->wdw_supported) {
	dev_err(dev, "suspend-in-wait not supported\n");
	return -EINVAL;
	}
	wdev->sleep_wait = true;
	}

	/*
	* The i.MX7D doesn't support low power mode, so we need to ping the watchdog
	* during suspend. Interaction with "fsl,suspend-in-wait" is unknown!
	*/
	wdev->no_ping = !of_device_is_compatible(dev->of_node, "fsl,imx7d-wdt");
	platform_set_drvdata(pdev, wdog);
	watchdog_set_drvdata(wdog, wdev);
	watchdog_set_nowayout(wdog, nowayout);
	watchdog_set_restart_priority(wdog, 128);
	watchdog_init_timeout(wdog, timeout, dev);
	if (wdev->no_ping)
	watchdog_stop_ping_on_suspend(wdog);

	if (imx2_wdt_is_running(wdev)) {
	imx2_wdt_set_timeout(wdog, wdog->timeout);
	set_bit(WDOG_HW_RUNNING, &wdog->status);
	}

	/*
	* Disable the watchdog power down counter at boot. Otherwise the power
	* down counter will pull down the #WDOG interrupt line for one clock
	* cycle.
	*/
	regmap_write(wdev->regmap, IMX2_WDT_WMCR, 0);

	return devm_watchdog_register_device(dev, wdog);
	}

	static void imx2_wdt_shutdown(struct platform_device *pdev)
	{
	struct watchdog_device *wdog = platform_get_drvdata(pdev);
	struct imx2_wdt_device *wdev = watchdog_get_drvdata(wdog);

	if (imx2_wdt_is_running(wdev)) {
	/*
	* We are running, configure max timeout before reboot
	* will take place.
	*/
	imx2_wdt_set_timeout(wdog, IMX2_WDT_MAX_TIME);
	imx2_wdt_ping(wdog);
	dev_crit(&pdev->dev, "Device shutdown.\n");
	}
	}

	/* Disable watchdog if it is active or non-active but still running */
	static int __maybe_unused imx2_wdt_suspend(struct device *dev)
	{
	struct watchdog_device *wdog = dev_get_drvdata(dev);
	struct imx2_wdt_device *wdev = watchdog_get_drvdata(wdog);

	/* The watchdog IP block is running */
	if (imx2_wdt_is_running(wdev)) {
	/*
	* Don't update wdog->timeout, we'll restore the current value
	* during resume.
	*/
	__imx2_wdt_set_timeout(wdog, IMX2_WDT_MAX_TIME);
	imx2_wdt_ping(wdog);
	}

	if (wdev->no_ping) {
	clk_disable_unprepare(wdev->clk);

	wdev->clk_is_on = false;
	}

	return 0;
	}

	/* Enable watchdog and configure it if necessary */
	static int __maybe_unused imx2_wdt_resume(struct device *dev)
	{
	struct watchdog_device *wdog = dev_get_drvdata(dev);
	struct imx2_wdt_device *wdev = watchdog_get_drvdata(wdog);
	int ret;

	if (wdev->no_ping) {
	ret = clk_prepare_enable(wdev->clk);

	if (ret)
	return ret;

	wdev->clk_is_on = true;
	}

	if (watchdog_active(wdog) && !imx2_wdt_is_running(wdev)) {
	/*
	* If the watchdog is still active and resumes
	* from deep sleep state, need to restart the
	* watchdog again.
	*/
	imx2_wdt_setup(wdog);
	}
	if (imx2_wdt_is_running(wdev)) {
	imx2_wdt_set_timeout(wdog, wdog->timeout);
	imx2_wdt_ping(wdog);
	}

	return 0;
	}

	static SIMPLE_DEV_PM_OPS(imx2_wdt_pm_ops, imx2_wdt_suspend,
	imx2_wdt_resume);

	static struct imx2_wdt_data imx_wdt = {
	.wdw_supported = true,
	};

	static struct imx2_wdt_data imx_wdt_legacy = {
	.wdw_supported = false,
	};

	static const struct of_device_id imx2_wdt_dt_ids[] = {
	{ .compatible = "fsl,imx21-wdt", .data = &imx_wdt_legacy },
	{ .compatible = "fsl,imx25-wdt", .data = &imx_wdt },
	{ .compatible = "fsl,imx27-wdt", .data = &imx_wdt_legacy },
	{ .compatible = "fsl,imx31-wdt", .data = &imx_wdt_legacy },
	{ .compatible = "fsl,imx35-wdt", .data = &imx_wdt },
	{ .compatible = "fsl,imx50-wdt", .data = &imx_wdt },
	{ .compatible = "fsl,imx51-wdt", .data = &imx_wdt },
	{ .compatible = "fsl,imx53-wdt", .data = &imx_wdt },
	{ .compatible = "fsl,imx6q-wdt", .data = &imx_wdt },
	{ .compatible = "fsl,imx6sl-wdt", .data = &imx_wdt },
	{ .compatible = "fsl,imx6sll-wdt", .data = &imx_wdt },
	{ .compatible = "fsl,imx6sx-wdt", .data = &imx_wdt },
	{ .compatible = "fsl,imx6ul-wdt", .data = &imx_wdt },
	{ .compatible = "fsl,imx7d-wdt", .data = &imx_wdt },
	{ .compatible = "fsl,imx8mm-wdt", .data = &imx_wdt },
	{ .compatible = "fsl,imx8mn-wdt", .data = &imx_wdt },
	{ .compatible = "fsl,imx8mp-wdt", .data = &imx_wdt },
	{ .compatible = "fsl,imx8mq-wdt", .data = &imx_wdt },
	{ .compatible = "fsl,ls1012a-wdt", .data = &imx_wdt_legacy },
	{ .compatible = "fsl,ls1043a-wdt", .data = &imx_wdt_legacy },
	{ .compatible = "fsl,vf610-wdt", .data = &imx_wdt },
	{ /* sentinel */ }
	};
	MODULE_DEVICE_TABLE(of, imx2_wdt_dt_ids);

	static struct platform_driver imx2_wdt_driver = {
	.shutdown = imx2_wdt_shutdown,
	.driver = {
	.name = DRIVER_NAME,
	.pm = &imx2_wdt_pm_ops,
	.of_match_table = imx2_wdt_dt_ids,
	},
	};

	module_platform_driver_probe(imx2_wdt_driver, imx2_wdt_probe);

	MODULE_AUTHOR("Wolfram Sang");
	MODULE_DESCRIPTION("Watchdog driver for IMX2 and later");
	MODULE_LICENSE("GPL v2");
	MODULE_ALIAS("platform:" DRIVER_NAME);