watchdog: Driver for the watchdog timer on Freescale IMX2 (and later) processors.

This is the driver for the hardware watchdog on the Freescale IMX2 and later processors.

Signed-off-by: Wolfram Sang <[e-mail]>
Cc: Vladimir Zapolskiy <[e-mail]>
Cc: Sascha Hauer <[e-mail]>
Tested-by: Juergen Beisert <[e-mail]>
Signed-off-by: Wim Van Sebroeck <[e-mail]>

drivers/watchdog/Kconfig

···
 	help
 	  Support for memory mapped max63{69,70,71,72,73,74} watchdog timer.
 
+config IMX2_WDT
+	tristate "IMX2+ Watchdog"
+	depends on ARCH_MX2 || ARCH_MX25 || ARCH_MX3 || ARCH_MX5
+	help
+	  This is the driver for the hardware watchdog
+	  on the Freescale IMX2 and later processors.
+	  If you have one of these processors and wish to have
+	  watchdog support enabled, say Y, otherwise say N.
+
+	  To compile this driver as a module, choose M here: the
+	  module will be called imx2_wdt.
+
 # AVR32 Architecture
 
 config AT32AP700X_WDT

drivers/watchdog/Makefile

···
 obj-$(CONFIG_NUC900_WATCHDOG) += nuc900_wdt.o
 obj-$(CONFIG_ADX_WATCHDOG) += adx_wdt.o
 obj-$(CONFIG_TS72XX_WATCHDOG) += ts72xx_wdt.o
+obj-$(CONFIG_IMX2_WDT) += imx2_wdt.o
 
 # AVR32 Architecture
 obj-$(CONFIG_AT32AP700X_WDT) += at32ap700x_wdt.o

drivers/watchdog/imx2_wdt.c

···
+/*
+ * Watchdog driver for IMX2 and later processors
+ *
+ *  Copyright (C) 2010 Wolfram Sang, Pengutronix e.K. <[e-mail]>
+ *
+ * some parts adapted by similar drivers from Darius Augulis and Vladimir
+ * Zapolskiy, additional improvements by Wim Van Sebroeck.
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 as published by
+ * the Free Software Foundation.
+ *
+ * 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/init.h>
+#include <linux/kernel.h>
+#include <linux/miscdevice.h>
+#include <linux/module.h>
+#include <linux/moduleparam.h>
+#include <linux/platform_device.h>
+#include <linux/watchdog.h>
+#include <linux/clk.h>
+#include <linux/fs.h>
+#include <linux/io.h>
+#include <linux/uaccess.h>
+#include <linux/timer.h>
+#include <linux/jiffies.h>
+#include <mach/hardware.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_WRE	(1 << 3)	/* -> WDOG Reset Enable */
+#define IMX2_WDT_WCR_WDE	(1 << 2)	/* -> Watchdog Enable */
+
+#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_MAX_TIME	128
+#define IMX2_WDT_DEFAULT_TIME	60		/* in seconds */
+
+#define WDOG_SEC_TO_COUNT(s)	((s * 2 - 1) << 8)
+
+#define IMX2_WDT_STATUS_OPEN	0
+#define IMX2_WDT_STATUS_STARTED	1
+#define IMX2_WDT_EXPECT_CLOSE	2
+
+static struct {
+	struct clk *clk;
+	void __iomem *base;
+	unsigned timeout;
+	unsigned long status;
+	struct timer_list timer;	/* Pings the watchdog when closed */
+} imx2_wdt;
+
+static struct miscdevice imx2_wdt_miscdev;
+
+static int nowayout = WATCHDOG_NOWAYOUT;
+module_param(nowayout, int, 0);
+MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default="
+				__MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
+
+
+static unsigned timeout = IMX2_WDT_DEFAULT_TIME;
+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 inline void imx2_wdt_setup(void)
+{
+	u16 val = __raw_readw(imx2_wdt.base + IMX2_WDT_WCR);
+
+	/* Strip the old watchdog Time-Out value */
+	val &= ~IMX2_WDT_WCR_WT;
+	/* Generate reset if WDOG times out */
+	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(imx2_wdt.timeout);
+
+	__raw_writew(val, imx2_wdt.base + IMX2_WDT_WCR);
+
+	/* enable the watchdog */
+	val |= IMX2_WDT_WCR_WDE;
+	__raw_writew(val, imx2_wdt.base + IMX2_WDT_WCR);
+}
+
+static inline void imx2_wdt_ping(void)
+{
+	__raw_writew(IMX2_WDT_SEQ1, imx2_wdt.base + IMX2_WDT_WSR);
+	__raw_writew(IMX2_WDT_SEQ2, imx2_wdt.base + IMX2_WDT_WSR);
+}
+
+static void imx2_wdt_timer_ping(unsigned long arg)
+{
+	/* ping it every imx2_wdt.timeout / 2 seconds to prevent reboot */
+	imx2_wdt_ping();
+	mod_timer(&imx2_wdt.timer, jiffies + imx2_wdt.timeout * HZ / 2);
+}
+
+static void imx2_wdt_start(void)
+{
+	if (!test_and_set_bit(IMX2_WDT_STATUS_STARTED, &imx2_wdt.status)) {
+		/* at our first start we enable clock and do initialisations */
+		clk_enable(imx2_wdt.clk);
+
+		imx2_wdt_setup();
+	} else	/* delete the timer that pings the watchdog after close */
+		del_timer_sync(&imx2_wdt.timer);
+
+	/* Watchdog is enabled - time to reload the timeout value */
+	imx2_wdt_ping();
+}
+
+static void imx2_wdt_stop(void)
+{
+	/* we don't need a clk_disable, it cannot be disabled once started.
+	 * We use a timer to ping the watchdog while /dev/watchdog is closed */
+	imx2_wdt_timer_ping(0);
+}
+
+static void imx2_wdt_set_timeout(int new_timeout)
+{
+	u16 val = __raw_readw(imx2_wdt.base + IMX2_WDT_WCR);
+
+	/* set the new timeout value in the WSR */
+	val &= ~IMX2_WDT_WCR_WT;
+	val |= WDOG_SEC_TO_COUNT(new_timeout);
+	__raw_writew(val, imx2_wdt.base + IMX2_WDT_WCR);
+}
+
+static int imx2_wdt_open(struct inode *inode, struct file *file)
+{
+	if (test_and_set_bit(IMX2_WDT_STATUS_OPEN, &imx2_wdt.status))
+		return -EBUSY;
+
+	imx2_wdt_start();
+	return nonseekable_open(inode, file);
+}
+
+static int imx2_wdt_close(struct inode *inode, struct file *file)
+{
+	if (test_bit(IMX2_WDT_EXPECT_CLOSE, &imx2_wdt.status) && !nowayout)
+		imx2_wdt_stop();
+	else {
+		dev_crit(imx2_wdt_miscdev.parent,
+			"Unexpected close: Expect reboot!\n");
+		imx2_wdt_ping();
+	}
+
+	clear_bit(IMX2_WDT_EXPECT_CLOSE, &imx2_wdt.status);
+	clear_bit(IMX2_WDT_STATUS_OPEN, &imx2_wdt.status);
+	return 0;
+}
+
+static long imx2_wdt_ioctl(struct file *file, unsigned int cmd,
+							unsigned long arg)
+{
+	void __user *argp = (void __user *)arg;
+	int __user *p = argp;
+	int new_value;
+
+	switch (cmd) {
+	case WDIOC_GETSUPPORT:
+		return copy_to_user(argp, &imx2_wdt_info,
+			sizeof(struct watchdog_info)) ? -EFAULT : 0;
+
+	case WDIOC_GETSTATUS:
+	case WDIOC_GETBOOTSTATUS:
+		return put_user(0, p);
+
+	case WDIOC_KEEPALIVE:
+		imx2_wdt_ping();
+		return 0;
+
+	case WDIOC_SETTIMEOUT:
+		if (get_user(new_value, p))
+			return -EFAULT;
+		if ((new_value < 1) || (new_value > IMX2_WDT_MAX_TIME))
+			return -EINVAL;
+		imx2_wdt_set_timeout(new_value);
+		imx2_wdt.timeout = new_value;
+		imx2_wdt_ping();
+
+		/* Fallthrough to return current value */
+	case WDIOC_GETTIMEOUT:
+		return put_user(imx2_wdt.timeout, p);
+
+	default:
+		return -ENOTTY;
+	}
+}
+
+static ssize_t imx2_wdt_write(struct file *file, const char __user *data,
+						size_t len, loff_t *ppos)
+{
+	size_t i;
+	char c;
+
+	if (len == 0)	/* Can we see this even ? */
+		return 0;
+
+	clear_bit(IMX2_WDT_EXPECT_CLOSE, &imx2_wdt.status);
+	/* scan to see whether or not we got the magic character */
+	for (i = 0; i != len; i++) {
+		if (get_user(c, data + i))
+			return -EFAULT;
+		if (c == 'V')
+			set_bit(IMX2_WDT_EXPECT_CLOSE, &imx2_wdt.status);
+	}
+
+	imx2_wdt_ping();
+	return len;
+}
+
+static const struct file_operations imx2_wdt_fops = {
+	.owner = THIS_MODULE,
+	.llseek = no_llseek,
+	.unlocked_ioctl = imx2_wdt_ioctl,
+	.open = imx2_wdt_open,
+	.release = imx2_wdt_close,
+	.write = imx2_wdt_write,
+};
+
+static struct miscdevice imx2_wdt_miscdev = {
+	.minor = WATCHDOG_MINOR,
+	.name = "watchdog",
+	.fops = &imx2_wdt_fops,
+};
+
+static int __init imx2_wdt_probe(struct platform_device *pdev)
+{
+	int ret;
+	int res_size;
+	struct resource *res;
+
+	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	if (!res) {
+		dev_err(&pdev->dev, "can't get device resources\n");
+		return -ENODEV;
+	}
+
+	res_size = resource_size(res);
+	if (!devm_request_mem_region(&pdev->dev, res->start, res_size,
+		res->name)) {
+		dev_err(&pdev->dev, "can't allocate %d bytes at %d address\n",
+			res_size, res->start);
+		return -ENOMEM;
+	}
+
+	imx2_wdt.base = devm_ioremap_nocache(&pdev->dev, res->start, res_size);
+	if (!imx2_wdt.base) {
+		dev_err(&pdev->dev, "ioremap failed\n");
+		return -ENOMEM;
+	}
+
+	imx2_wdt.clk = clk_get_sys("imx-wdt.0", NULL);
+	if (IS_ERR(imx2_wdt.clk)) {
+		dev_err(&pdev->dev, "can't get Watchdog clock\n");
+		return PTR_ERR(imx2_wdt.clk);
+	}
+
+	imx2_wdt.timeout = clamp_t(unsigned, timeout, 1, IMX2_WDT_MAX_TIME);
+	if (imx2_wdt.timeout != timeout)
+		dev_warn(&pdev->dev, "Initial timeout out of range! "
+			"Clamped from %u to %u\n", timeout, imx2_wdt.timeout);
+
+	setup_timer(&imx2_wdt.timer, imx2_wdt_timer_ping, 0);
+
+	imx2_wdt_miscdev.parent = &pdev->dev;
+	ret = misc_register(&imx2_wdt_miscdev);
+	if (ret)
+		goto fail;
+
+	dev_info(&pdev->dev,
+		"IMX2+ Watchdog Timer enabled. timeout=%ds (nowayout=%d)\n",
+						imx2_wdt.timeout, nowayout);
+	return 0;
+
+fail:
+	imx2_wdt_miscdev.parent = NULL;
+	clk_put(imx2_wdt.clk);
+	return ret;
+}
+
+static int __exit imx2_wdt_remove(struct platform_device *pdev)
+{
+	misc_deregister(&imx2_wdt_miscdev);
+
+	if (test_bit(IMX2_WDT_STATUS_STARTED, &imx2_wdt.status)) {
+		del_timer_sync(&imx2_wdt.timer);
+
+		dev_crit(imx2_wdt_miscdev.parent,
+			"Device removed: Expect reboot!\n");
+	} else
+		clk_put(imx2_wdt.clk);
+
+	imx2_wdt_miscdev.parent = NULL;
+	return 0;
+}
+
+static void imx2_wdt_shutdown(struct platform_device *pdev)
+{
+	if (test_bit(IMX2_WDT_STATUS_STARTED, &imx2_wdt.status)) {
+		/* we are running, we need to delete the timer but will give
+		 * max timeout before reboot will take place */
+		del_timer_sync(&imx2_wdt.timer);
+		imx2_wdt_set_timeout(IMX2_WDT_MAX_TIME);
+		imx2_wdt_ping();
+
+		dev_crit(imx2_wdt_miscdev.parent,
+			"Device shutdown: Expect reboot!\n");
+	}
+}
+
+static struct platform_driver imx2_wdt_driver = {
+	.probe		= imx2_wdt_probe,
+	.remove		= __exit_p(imx2_wdt_remove),
+	.shutdown	= imx2_wdt_shutdown,
+	.driver		= {
+		.name	= DRIVER_NAME,
+		.owner	= THIS_MODULE,
+	},
+};
+
+static int __init imx2_wdt_init(void)
+{
+	return platform_driver_probe(&imx2_wdt_driver, imx2_wdt_probe);
+}
+module_init(imx2_wdt_init);
+
+static void __exit imx2_wdt_exit(void)
+{
+	platform_driver_unregister(&imx2_wdt_driver);
+}
+module_exit(imx2_wdt_exit);
+
+MODULE_AUTHOR("Wolfram Sang");
+MODULE_DESCRIPTION("Watchdog driver for IMX2 and later");
+MODULE_LICENSE("GPL v2");
+MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);
+MODULE_ALIAS("platform:" DRIVER_NAME);