[PATCH] watchdog: Add support for the WM8350 watchdog

[PATCH] watchdog: Add support for the WM8350 watchdog

[Mark Brown]

This driver implements support for the watchdog functionality provided
by the Wolfson Microelectronics WM8350, a multi-function audio and
power management subsystem intended for use in embedded systems. It is
based on a driver originally written by Graeme Gregory, though it has
been extensively modified since then.

Use of a GPIO to kick the watchdog is not yet supported.

Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>
---

Since last submission the driver has been changed to use bit zero rather
than bit 1 when using test_and_set_bit() to ensure that we only have
one user.

 drivers/watchdog/Kconfig      |    7 +
 drivers/watchdog/Makefile     |    1 +
 drivers/watchdog/wm8350_wdt.c |  329 +++++++++++++++++++++++++++++++++++++++++
 3 files changed, 337 insertions(+), 0 deletions(-)
 create mode 100644 drivers/watchdog/wm8350_wdt.c

diff --git a/drivers/watchdog/Kconfig b/drivers/watchdog/Kconfig
index 4fd3fa5..d5bc085 100644
--- a/drivers/watchdog/Kconfig
+++ b/drivers/watchdog/Kconfig
@@ -55,6 +55,13 @@ config SOFT_WATCHDOG
 	  To compile this driver as a module, choose M here: the
 	  module will be called softdog.
 
+config WM8350_WATCHDOG
+	tristate "WM8350 watchdog"
+	depends on MFD_WM8350
+	help
+	  Support for the watchdog in the WM8350 AudioPlus PMIC.  When
+	  the watchdog triggers the system will be reset.
+
 # ALPHA Architecture
 
 # ARM Architecture
diff --git a/drivers/watchdog/Makefile b/drivers/watchdog/Makefile
index e352bbb..c3b8db3 100644
--- a/drivers/watchdog/Makefile
+++ b/drivers/watchdog/Makefile
@@ -134,3 +134,4 @@ obj-$(CONFIG_WATCHDOG_CP1XXX)		+= cpwd.o
 
 # Architecture Independant
 obj-$(CONFIG_SOFT_WATCHDOG) += softdog.o
+obj-$(CONFIG_WM8350_WATCHDOG) += wm8350_wdt.o
diff --git a/drivers/watchdog/wm8350_wdt.c b/drivers/watchdog/wm8350_wdt.c
new file mode 100644
index 0000000..d7b8ad4
--- /dev/null
+++ b/drivers/watchdog/wm8350_wdt.c
@@ -0,0 +1,329 @@
+/*
+ * Watchdog driver for the wm8350
+ *
+ * Copyright (C) 2007, 2008 Wolfson Microelectronics <linux@wolfsonmicro.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
+ */
+
+#include <linux/module.h>
+#include <linux/moduleparam.h>
+#include <linux/types.h>
+#include <linux/kernel.h>
+#include <linux/fs.h>
+#include <linux/miscdevice.h>
+#include <linux/platform_device.h>
+#include <linux/watchdog.h>
+#include <linux/uaccess.h>
+#include <linux/mfd/wm8350/core.h>
+
+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 long wm8350_wdt_users;
+static struct miscdevice wm8350_wdt_miscdev;
+static int wm8350_wdt_expect_close;
+static DEFINE_MUTEX(wdt_mutex);
+
+static struct {
+	int time;  /* Seconds */
+	u16 val;   /* To be set in WM8350_SYSTEM_CONTROL_2 */
+} wm8350_wdt_cfgs[] = {
+	{ 1, 0x02 },
+	{ 2, 0x04 },
+	{ 4, 0x05 },
+};
+
+static struct wm8350 *get_wm8350(void)
+{
+	return dev_get_drvdata(wm8350_wdt_miscdev.parent);
+}
+
+static int wm8350_wdt_set_timeout(struct wm8350 *wm8350, u16 value)
+{
+	int ret;
+	u16 reg;
+
+	mutex_lock(&wdt_mutex);
+	wm8350_reg_unlock(wm8350);
+
+	reg = wm8350_reg_read(wm8350, WM8350_SYSTEM_CONTROL_2);
+	reg &= ~WM8350_WDOG_TO_MASK;
+	reg |= value;
+	ret = wm8350_reg_write(wm8350, WM8350_SYSTEM_CONTROL_2, reg);
+
+	wm8350_reg_lock(wm8350);
+	mutex_unlock(&wdt_mutex);
+
+	return ret;
+}
+
+static int wm8350_wdt_start(struct wm8350 *wm8350)
+{
+	int ret;
+	u16 reg;
+
+	mutex_lock(&wdt_mutex);
+	wm8350_reg_unlock(wm8350);
+
+	reg = wm8350_reg_read(wm8350, WM8350_SYSTEM_CONTROL_2);
+	reg &= ~WM8350_WDOG_MODE_MASK;
+	reg |= 0x20;
+	ret = wm8350_reg_write(wm8350, WM8350_SYSTEM_CONTROL_2, reg);
+
+	wm8350_reg_lock(wm8350);
+	mutex_unlock(&wdt_mutex);
+
+	return ret;
+}
+
+static int wm8350_wdt_stop(struct wm8350 *wm8350)
+{
+	int ret;
+	u16 reg;
+
+	mutex_lock(&wdt_mutex);
+	wm8350_reg_unlock(wm8350);
+
+	reg = wm8350_reg_read(wm8350, WM8350_SYSTEM_CONTROL_2);
+	reg &= ~WM8350_WDOG_MODE_MASK;
+	ret = wm8350_reg_write(wm8350, WM8350_SYSTEM_CONTROL_2, reg);
+
+	wm8350_reg_lock(wm8350);
+	mutex_unlock(&wdt_mutex);
+
+	return ret;
+}
+
+static int wm8350_wdt_kick(struct wm8350 *wm8350)
+{
+	int ret;
+	u16 reg;
+
+	mutex_lock(&wdt_mutex);
+
+	reg = wm8350_reg_read(wm8350, WM8350_SYSTEM_CONTROL_2);
+	ret = wm8350_reg_write(wm8350, WM8350_SYSTEM_CONTROL_2, reg);
+
+	mutex_unlock(&wdt_mutex);
+
+	return ret;
+}
+
+static int wm8350_wdt_open(struct inode *inode, struct file *file)
+{
+	struct wm8350 *wm8350 = get_wm8350();
+	int ret;
+
+	if (!wm8350)
+		return -ENODEV;
+
+	if (test_and_set_bit(0, &wm8350_wdt_users))
+		return -EBUSY;
+
+	ret = wm8350_wdt_start(wm8350);
+	if (ret != 0)
+		return ret;
+
+	return nonseekable_open(inode, file);
+}
+
+static int wm8350_wdt_release(struct inode *inode, struct file *file)
+{
+	struct wm8350 *wm8350 = get_wm8350();
+
+	if (wm8350_wdt_expect_close)
+		wm8350_wdt_stop(wm8350);
+	else {
+		dev_warn(wm8350->dev, "Watchdog device closed uncleanly\n");
+		wm8350_wdt_kick(wm8350);
+	}
+
+	clear_bit(0, &wm8350_wdt_users);
+
+	return 0;
+}
+
+static ssize_t wm8350_wdt_write(struct file *file,
+				const char __user *data, size_t count,
+				loff_t *ppos)
+{
+	struct wm8350 *wm8350 = get_wm8350();
+	size_t i;
+
+	if (count) {
+		wm8350_wdt_kick(wm8350);
+
+		if (!nowayout) {
+			/* In case it was set long ago */
+			wm8350_wdt_expect_close = 0;
+
+			/* scan to see whether or not we got the magic
+			   character */
+			for (i = 0; i != count; i++) {
+				char c;
+				if (get_user(c, data + i))
+					return -EFAULT;
+				if (c == 'V')
+					wm8350_wdt_expect_close = 42;
+			}
+		}
+	}
+	return count;
+}
+
+static struct watchdog_info ident = {
+	.options = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING | WDIOF_MAGICCLOSE,
+	.identity = "WM8350 Watchdog",
+};
+
+static long wm8350_wdt_ioctl(struct file *file, unsigned int cmd,
+			     unsigned long arg)
+{
+	struct wm8350 *wm8350 = get_wm8350();
+	int ret = -ENOTTY, time, i;
+	void __user *argp = (void __user *)arg;
+	int __user *p = argp;
+	u16 reg;
+
+	switch (cmd) {
+	case WDIOC_GETSUPPORT:
+		ret = copy_to_user(argp, &ident, sizeof(ident)) ? -EFAULT : 0;
+		break;
+
+	case WDIOC_GETSTATUS:
+	case WDIOC_GETBOOTSTATUS:
+		ret = put_user(0, p);
+		break;
+
+	case WDIOC_SETTIMEOUT:
+		ret = get_user(time, p);
+		if (ret)
+			break;
+
+		if (time == 0) {
+			if (nowayout)
+				ret = -EINVAL;
+			else
+				wm8350_wdt_stop(wm8350);
+			break;
+		}
+
+		for (i = 0; i < ARRAY_SIZE(wm8350_wdt_cfgs); i++)
+			if (wm8350_wdt_cfgs[i].time == time)
+				break;
+		if (i == ARRAY_SIZE(wm8350_wdt_cfgs))
+			ret = -EINVAL;
+		else
+			ret = wm8350_wdt_set_timeout(wm8350,
+						     wm8350_wdt_cfgs[i].val);
+		break;
+
+	case WDIOC_GETTIMEOUT:
+		reg = wm8350_reg_read(wm8350, WM8350_SYSTEM_CONTROL_2);
+		reg &= WM8350_WDOG_TO_MASK;
+		for (i = 0; i < ARRAY_SIZE(wm8350_wdt_cfgs); i++)
+			if (wm8350_wdt_cfgs[i].val == reg)
+				break;
+		if (i == ARRAY_SIZE(wm8350_wdt_cfgs)) {
+			dev_warn(wm8350->dev,
+				 "Unknown watchdog configuration: %x\n", reg);
+			ret = -EINVAL;
+		} else
+			ret = put_user(wm8350_wdt_cfgs[i].time, p);
+		break;
+
+	case WDIOC_KEEPALIVE:
+		ret = wm8350_wdt_kick(wm8350);
+		break;
+
+	case WDIOC_SETOPTIONS:
+	{
+		int options;
+
+		if (get_user(options, p))
+			return -EFAULT;
+
+		ret = -EINVAL;
+
+		/* Setting both simultaneously means at least one must fail */
+		if (options == WDIOS_DISABLECARD)
+			ret = wm8350_wdt_start(wm8350);
+
+		if (options == WDIOS_ENABLECARD)
+			ret = wm8350_wdt_stop(wm8350);
+	}
+
+	}
+
+	return ret;
+}
+
+static const struct file_operations wm8350_wdt_fops = {
+	.owner = THIS_MODULE,
+	.llseek = no_llseek,
+	.write = wm8350_wdt_write,
+	.unlocked_ioctl = wm8350_wdt_ioctl,
+	.open = wm8350_wdt_open,
+	.release = wm8350_wdt_release,
+};
+
+static struct miscdevice wm8350_wdt_miscdev = {
+	.minor = WATCHDOG_MINOR,
+	.name = "watchdog",
+	.fops = &wm8350_wdt_fops,
+};
+
+static int wm8350_wdt_probe(struct platform_device *pdev)
+{
+	struct wm8350 *wm8350 = platform_get_drvdata(pdev);
+
+	if (!wm8350) {
+		dev_err(wm8350->dev, "No driver data supplied\n");
+		return -ENODEV;
+	}
+
+	/* Default to 4s timeout */
+	wm8350_wdt_set_timeout(wm8350, 0x05);
+
+	wm8350_wdt_miscdev.parent = &pdev->dev;
+
+	return misc_register(&wm8350_wdt_miscdev);
+}
+
+static int __exit wm8350_wdt_remove(struct platform_device *pdev)
+{
+	misc_deregister(&wm8350_wdt_miscdev);
+
+	return 0;
+}
+
+static struct platform_driver wm8350_wdt_driver = {
+	.probe = wm8350_wdt_probe,
+	.remove = wm8350_wdt_remove,
+	.driver = {
+		.name = "wm8350-wdt",
+	},
+};
+
+static int __init wm8350_wdt_init(void)
+{
+	return platform_driver_register(&wm8350_wdt_driver);
+}
+module_init(wm8350_wdt_init);
+
+static void __exit wm8350_wdt_exit(void)
+{
+	platform_driver_unregister(&wm8350_wdt_driver);
+}
+module_exit(wm8350_wdt_exit);
+
+MODULE_AUTHOR("Mark Brown");
+MODULE_DESCRIPTION("WM8350 Watchdog");
+MODULE_LICENSE("GPL");
+MODULE_ALIAS("platform:wm8350-wdt");
-- 
1.5.6.5

Re: [PATCH] watchdog: Add support for the WM8350 watchdog

[Mark Brown]

On Thu, Oct 30, 2008 at 03:18:04PM -0700, Andrew Morton wrote:
> Mark Brown <broonie@opensource.wolfsonmicro.com> wrote:

> > +	wm8350_reg_lock(wm8350);

> I was curious about this wm8350_reg_lock/wm8350_reg_unlock thing, so I
> went to have a look at it.  Nothing.  Obviously its authors felt there
> was no benefit in having anyone else understand what it does.

Well, there's really not that much more to it than what the function
names say - some of the registers can be locked in hardware, meaning
that the lock needs to be unlocked when writing to them.  I'll come up
with some sort of blurb and send a patch to Samuel but I'm not sure how
much it'll actually help.

This is mostly for things particularly likely to cause damage to the
system - in this case the hardware supports extremely short timeouts
which might be too short to be able to kick the watchdog again if it
fires and reboots (the lowest option is 0.125s IIRC).  The only way
to recover from that is to remove all power from the system.

> > +	if (test_and_set_bit(1, &wm8350_wdt_users))

> It's odd that the driver uses bit 1 rather than bit 0.

Hrm, yeah.  No idea why, the driver was like that when I first looked at
it and I can't see any history explaining the choice.

Re: [PATCH] watchdog: Add support for the WM8350 watchdog

[Andrew Morton]

On Mon, 27 Oct 2008 15:31:56 +0000
Mark Brown <broonie@opensource.wolfsonmicro.com> wrote:

> This driver implements support for the watchdog functionality provided
> by the Wolfson Microelectronics WM8350, a multi-function audio and
> power management subsystem intended for use in embedded systems. It is
> based on a driver originally written by Graeme Gregory, though it has
> been extensively modified since then.
> 
> Use of a GPIO to kick the watchdog is not yet supported.
> 
> ...
>
> +
> +static int wm8350_wdt_set_timeout(struct wm8350 *wm8350, u16 value)
> +{
> +	int ret;
> +	u16 reg;
> +
> +	mutex_lock(&wdt_mutex);
> +	wm8350_reg_unlock(wm8350);
> +
> +	reg = wm8350_reg_read(wm8350, WM8350_SYSTEM_CONTROL_2);
> +	reg &= ~WM8350_WDOG_TO_MASK;
> +	reg |= value;
> +	ret = wm8350_reg_write(wm8350, WM8350_SYSTEM_CONTROL_2, reg);
> +
> +	wm8350_reg_lock(wm8350);

I was curious about this wm8350_reg_lock/wm8350_reg_unlock thing, so I
went to have a look at it.  Nothing.  Obviously its authors felt there
was no benefit in having anyone else understand what it does.

> +	mutex_unlock(&wdt_mutex);
> +
> +	return ret;
> +}
>
> ...
>
> +static int wm8350_wdt_open(struct inode *inode, struct file *file)
> +{
> +	struct wm8350 *wm8350 = get_wm8350();
> +	int ret;
> +
> +	if (!wm8350)
> +		return -ENODEV;
> +
> +	if (test_and_set_bit(1, &wm8350_wdt_users))

It's odd that the driver uses bit 1 rather than bit 0.

[PATCH] watchdog: Add support for the WM8350 watchdog

[Mark Brown]

This driver implements support for the watchdog functionality provided
by the Wolfson Microelectronics WM8350, a multi-function audio and
power management subsystem intended for use in embedded systems. It is
based on a driver originally written by Graeme Gregory, though it has
been extensively modified since then.

Use of a GPIO to kick the watchdog is not yet supported.

Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>
---

Changes since last submission (which should address all the feedback):

 - Implement GETBOOTSTATUS as an alias for GETSTATUS.
 - Use unlocked_ioctl, adding a mutex for hardware access.
 - Ping the watchdog when we close it uncleanly.
 - Remove debug printk().

 drivers/watchdog/Kconfig      |    7 +
 drivers/watchdog/Makefile     |    1 +
 drivers/watchdog/wm8350_wdt.c |  329 +++++++++++++++++++++++++++++++++++++++++
 3 files changed, 337 insertions(+), 0 deletions(-)
 create mode 100644 drivers/watchdog/wm8350_wdt.c

diff --git a/drivers/watchdog/Kconfig b/drivers/watchdog/Kconfig
index 1a22fe7..b93e334 100644
--- a/drivers/watchdog/Kconfig
+++ b/drivers/watchdog/Kconfig
@@ -55,6 +55,13 @@ config SOFT_WATCHDOG
 	  To compile this driver as a module, choose M here: the
 	  module will be called softdog.
 
+config WM8350_WATCHDOG
+	tristate "WM8350 watchdog"
+	depends on MFD_WM8350
+	help
+	  Support for the watchdog in the WM8350 AudioPlus PMIC.  When
+	  the watchdog triggers the system will be reset.
+
 # ALPHA Architecture
 
 # ARM Architecture
diff --git a/drivers/watchdog/Makefile b/drivers/watchdog/Makefile
index e352bbb..c3b8db3 100644
--- a/drivers/watchdog/Makefile
+++ b/drivers/watchdog/Makefile
@@ -134,3 +134,4 @@ obj-$(CONFIG_WATCHDOG_CP1XXX)		+= cpwd.o
 
 # Architecture Independant
 obj-$(CONFIG_SOFT_WATCHDOG) += softdog.o
+obj-$(CONFIG_WM8350_WATCHDOG) += wm8350_wdt.o
diff --git a/drivers/watchdog/wm8350_wdt.c b/drivers/watchdog/wm8350_wdt.c
new file mode 100644
index 0000000..748a7f3
--- /dev/null
+++ b/drivers/watchdog/wm8350_wdt.c
@@ -0,0 +1,329 @@
+/*
+ * Watchdog driver for the wm8350
+ *
+ * Copyright (C) 2007, 2008 Wolfson Microelectronics <linux@wolfsonmicro.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
+ */
+
+#include <linux/module.h>
+#include <linux/moduleparam.h>
+#include <linux/types.h>
+#include <linux/kernel.h>
+#include <linux/fs.h>
+#include <linux/miscdevice.h>
+#include <linux/platform_device.h>
+#include <linux/watchdog.h>
+#include <linux/uaccess.h>
+#include <linux/mfd/wm8350/core.h>
+
+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 long wm8350_wdt_users;
+static struct miscdevice wm8350_wdt_miscdev;
+static int wm8350_wdt_expect_close;
+static DEFINE_MUTEX(wdt_mutex);
+
+static struct {
+	int time;  /* Seconds */
+	u16 val;   /* To be set in WM8350_SYSTEM_CONTROL_2 */
+} wm8350_wdt_cfgs[] = {
+	{ 1, 0x02 },
+	{ 2, 0x04 },
+	{ 4, 0x05 },
+};
+
+static struct wm8350 *get_wm8350(void)
+{
+	return dev_get_drvdata(wm8350_wdt_miscdev.parent);
+}
+
+static int wm8350_wdt_set_timeout(struct wm8350 *wm8350, u16 value)
+{
+	int ret;
+	u16 reg;
+
+	mutex_lock(&wdt_mutex);
+	wm8350_reg_unlock(wm8350);
+
+	reg = wm8350_reg_read(wm8350, WM8350_SYSTEM_CONTROL_2);
+	reg &= ~WM8350_WDOG_TO_MASK;
+	reg |= value;
+	ret = wm8350_reg_write(wm8350, WM8350_SYSTEM_CONTROL_2, reg);
+
+	wm8350_reg_lock(wm8350);
+	mutex_unlock(&wdt_mutex);
+
+	return ret;
+}
+
+static int wm8350_wdt_start(struct wm8350 *wm8350)
+{
+	int ret;
+	u16 reg;
+
+	mutex_lock(&wdt_mutex);
+	wm8350_reg_unlock(wm8350);
+
+	reg = wm8350_reg_read(wm8350, WM8350_SYSTEM_CONTROL_2);
+	reg &= ~WM8350_WDOG_MODE_MASK;
+	reg |= 0x20;
+	ret = wm8350_reg_write(wm8350, WM8350_SYSTEM_CONTROL_2, reg);
+
+	wm8350_reg_lock(wm8350);
+	mutex_unlock(&wdt_mutex);
+
+	return ret;
+}
+
+static int wm8350_wdt_stop(struct wm8350 *wm8350)
+{
+	int ret;
+	u16 reg;
+
+	mutex_lock(&wdt_mutex);
+	wm8350_reg_unlock(wm8350);
+
+	reg = wm8350_reg_read(wm8350, WM8350_SYSTEM_CONTROL_2);
+	reg &= ~WM8350_WDOG_MODE_MASK;
+	ret = wm8350_reg_write(wm8350, WM8350_SYSTEM_CONTROL_2, reg);
+
+	wm8350_reg_lock(wm8350);
+	mutex_unlock(&wdt_mutex);
+
+	return ret;
+}
+
+static int wm8350_wdt_kick(struct wm8350 *wm8350)
+{
+	int ret;
+	u16 reg;
+
+	mutex_lock(&wdt_mutex);
+
+	reg = wm8350_reg_read(wm8350, WM8350_SYSTEM_CONTROL_2);
+	ret = wm8350_reg_write(wm8350, WM8350_SYSTEM_CONTROL_2, reg);
+
+	mutex_unlock(&wdt_mutex);
+
+	return ret;
+}
+
+static int wm8350_wdt_open(struct inode *inode, struct file *file)
+{
+	struct wm8350 *wm8350 = get_wm8350();
+	int ret;
+
+	if (!wm8350)
+		return -ENODEV;
+
+	if (test_and_set_bit(1, &wm8350_wdt_users))
+		return -EBUSY;
+
+	ret = wm8350_wdt_start(wm8350);
+	if (ret != 0)
+		return ret;
+
+	return nonseekable_open(inode, file);
+}
+
+static int wm8350_wdt_release(struct inode *inode, struct file *file)
+{
+	struct wm8350 *wm8350 = get_wm8350();
+
+	if (wm8350_wdt_expect_close)
+		wm8350_wdt_stop(wm8350);
+	else {
+		dev_warn(wm8350->dev, "Watchdog device closed uncleanly\n");
+		wm8350_wdt_kick(wm8350);
+	}
+
+	clear_bit(1, &wm8350_wdt_users);
+
+	return 0;
+}
+
+static ssize_t wm8350_wdt_write(struct file *file,
+				const char __user *data, size_t count,
+				loff_t *ppos)
+{
+	struct wm8350 *wm8350 = get_wm8350();
+	size_t i;
+
+	if (count) {
+		wm8350_wdt_kick(wm8350);
+
+		if (!nowayout) {
+			/* In case it was set long ago */
+			wm8350_wdt_expect_close = 0;
+
+			/* scan to see whether or not we got the magic
+			   character */
+			for (i = 0; i != count; i++) {
+				char c;
+				if (get_user(c, data + i))
+					return -EFAULT;
+				if (c == 'V')
+					wm8350_wdt_expect_close = 42;
+			}
+		}
+	}
+	return count;
+}
+
+static struct watchdog_info ident = {
+	.options = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING | WDIOF_MAGICCLOSE,
+	.identity = "WM8350 Watchdog",
+};
+
+static long wm8350_wdt_ioctl(struct file *file, unsigned int cmd,
+			     unsigned long arg)
+{
+	struct wm8350 *wm8350 = get_wm8350();
+	int ret = -ENOTTY, time, i;
+	void __user *argp = (void __user *)arg;
+	int __user *p = argp;
+	u16 reg;
+
+	switch (cmd) {
+	case WDIOC_GETSUPPORT:
+		ret = copy_to_user(argp, &ident, sizeof(ident)) ? -EFAULT : 0;
+		break;
+
+	case WDIOC_GETSTATUS:
+	case WDIOC_GETBOOTSTATUS:
+		ret = put_user(0, p);
+		break;
+
+	case WDIOC_SETTIMEOUT:
+		ret = get_user(time, p);
+		if (ret)
+			break;
+
+		if (time == 0) {
+			if (nowayout)
+				ret = -EINVAL;
+			else
+				wm8350_wdt_stop(wm8350);
+			break;
+		}
+
+		for (i = 0; i < ARRAY_SIZE(wm8350_wdt_cfgs); i++)
+			if (wm8350_wdt_cfgs[i].time == time)
+				break;
+		if (i == ARRAY_SIZE(wm8350_wdt_cfgs))
+			ret = -EINVAL;
+		else
+			ret = wm8350_wdt_set_timeout(wm8350,
+						     wm8350_wdt_cfgs[i].val);
+		break;
+
+	case WDIOC_GETTIMEOUT:
+		reg = wm8350_reg_read(wm8350, WM8350_SYSTEM_CONTROL_2);
+		reg &= WM8350_WDOG_TO_MASK;
+		for (i = 0; i < ARRAY_SIZE(wm8350_wdt_cfgs); i++)
+			if (wm8350_wdt_cfgs[i].val == reg)
+				break;
+		if (i == ARRAY_SIZE(wm8350_wdt_cfgs)) {
+			dev_warn(wm8350->dev,
+				 "Unknown watchdog configuration: %x\n", reg);
+			ret = -EINVAL;
+		} else
+			ret = put_user(wm8350_wdt_cfgs[i].time, p);
+		break;
+
+	case WDIOC_KEEPALIVE:
+		ret = wm8350_wdt_kick(wm8350);
+		break;
+
+	case WDIOC_SETOPTIONS:
+	{
+		int options;
+
+		if (get_user(options, p))
+			return -EFAULT;
+
+		ret = -EINVAL;
+
+		/* Setting both simultaneously means at least one must fail */
+		if (options == WDIOS_DISABLECARD)
+			ret = wm8350_wdt_start(wm8350);
+
+		if (options == WDIOS_ENABLECARD)
+			ret = wm8350_wdt_stop(wm8350);
+	}
+
+	}
+
+	return ret;
+}
+
+static const struct file_operations wm8350_wdt_fops = {
+	.owner = THIS_MODULE,
+	.llseek = no_llseek,
+	.write = wm8350_wdt_write,
+	.unlocked_ioctl = wm8350_wdt_ioctl,
+	.open = wm8350_wdt_open,
+	.release = wm8350_wdt_release,
+};
+
+static struct miscdevice wm8350_wdt_miscdev = {
+	.minor = WATCHDOG_MINOR,
+	.name = "watchdog",
+	.fops = &wm8350_wdt_fops,
+};
+
+static int wm8350_wdt_probe(struct platform_device *pdev)
+{
+	struct wm8350 *wm8350 = platform_get_drvdata(pdev);
+
+	if (!wm8350) {
+		dev_err(wm8350->dev, "No driver data supplied\n");
+		return -ENODEV;
+	}
+
+	/* Default to 4s timeout */
+	wm8350_wdt_set_timeout(wm8350, 0x05);
+
+	wm8350_wdt_miscdev.parent = &pdev->dev;
+
+	return misc_register(&wm8350_wdt_miscdev);
+}
+
+static int __exit wm8350_wdt_remove(struct platform_device *pdev)
+{
+	misc_deregister(&wm8350_wdt_miscdev);
+
+	return 0;
+}
+
+static struct platform_driver wm8350_wdt_driver = {
+	.probe = wm8350_wdt_probe,
+	.remove = wm8350_wdt_remove,
+	.driver = {
+		.name = "wm8350-wdt",
+	},
+};
+
+static int __init wm8350_wdt_init(void)
+{
+	return platform_driver_register(&wm8350_wdt_driver);
+}
+module_init(wm8350_wdt_init);
+
+static void __exit wm8350_wdt_exit(void)
+{
+	platform_driver_unregister(&wm8350_wdt_driver);
+}
+module_exit(wm8350_wdt_exit);
+
+MODULE_AUTHOR("Mark Brown");
+MODULE_DESCRIPTION("WM8350 Watchdog");
+MODULE_LICENSE("GPL");
+MODULE_ALIAS("platform:wm8350-wdt");
-- 
1.5.6.5

Re: [PATCH] watchdog: Add support for the WM8350 watchdog

[Wim Van Sebroeck]

Hi Marc,

Finally a stable ADSL line again. I just finished reviewing your driver:

> +static int wm8350_wdt_open(struct inode *inode, struct file *file)
> +{
> +	struct wm8350 *wm8350 = get_wm8350();
> +	int ret;
> +
> +	if (!wm8350) {
> +		printk(KERN_CRIT "FNORD\n");

:-) as you pointed out this should be removed.

> +static int wm8350_wdt_release(struct inode *inode, struct file *file)
> +{
> +	struct wm8350 *wm8350 = get_wm8350();
> +
> +	if (wm8350_wdt_expect_close)
> +		wm8350_wdt_stop(wm8350);
> +	else
> +		dev_warn(wm8350->dev, "Watchdog device closed uncleanly\n");

you should ping the watchdog if you don't stop it.

> +static int wm8350_wdt_ioctl(struct inode *inode, struct file *file,
> +			    unsigned int cmd, unsigned long arg)

we use the unlocked_ioctl call in watchdog drivers now. So this should be:
static long wm8350_wdt_ioctl(struct file *file, unsigned int cmd,
						unsigned long arg)

> +{
> +	struct wm8350 *wm8350 = get_wm8350();
> +	int ret = -ENOTTY, time, i;
> +	void __user *argp = (void __user *)arg;
> +	int __user *p = argp;
> +	u16 reg;
> +
> +	switch (cmd) {
> +	case WDIOC_GETSUPPORT:
> +		ret = copy_to_user(argp, &ident, sizeof(ident)) ? -EFAULT : 0;
> +		break;
> +
> +	case WDIOC_GETSTATUS:

Bootstatus is a mandatory ioctl according to the API. So just add:
	case WDIOC_GETBOOTSTATUS:

> +static const struct file_operations wm8350_wdt_fops = {
> +	.owner = THIS_MODULE,
> +	.llseek = no_llseek,
> +	.write = wm8350_wdt_write,
> +	.ioctl = wm8350_wdt_ioctl,

and for the unlocked_ioctl call this needs to be:
	.unlocked_ioctl = wm8350_wdt_ioctl,

For the rest: seems OK to me.

Kind regards,
Wim.

Re: [PATCH] watchdog: Add support for the WM8350 watchdog

[Mark Brown]

On Mon, Oct 20, 2008 at 08:12:11PM +0100, Mark Brown wrote:

> +	if (!wm8350) {
> +		printk(KERN_CRIT "FNORD\n");

Gah, obviously this printk() shouldn't be there - I'll submit an updated
version once you've had time to review this.  Sorry about that.

Re: [PATCH] watchdog: Add support for the WM8350 watchdog

[Wim Van Sebroeck]

Hi Mark,

> This driver implements support for the watchdog functionality provided
> by the Wolfson Microelectronics WM8350, a multi-function audio and
> power management subsystem intended for use in embedded systems. It is
> based on a driver originally written by Graeme Gregory, though it has
> been extensively modified since then.
> 
> Use of a GPIO to kick the watchdog is not yet supported.
> 
> Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>

Reviewing this one. Will get back on this driver tomorrow.

Kind regards,
Wim.

[PATCH] watchdog: Add support for the WM8350 watchdog

[Mark Brown]

This driver implements support for the watchdog functionality provided
by the Wolfson Microelectronics WM8350, a multi-function audio and
power management subsystem intended for use in embedded systems. It is
based on a driver originally written by Graeme Gregory, though it has
been extensively modified since then.

Use of a GPIO to kick the watchdog is not yet supported.

Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>
---

This driver is unchanged since the last submission but since the WM8350
core support has now been merged into mainline with registration of the
watchdog device already present this patch should now be directly
mergable.

 drivers/watchdog/Kconfig      |    7 +
 drivers/watchdog/Makefile     |    1 +
 drivers/watchdog/wm8350_wdt.c |  316 +++++++++++++++++++++++++++++++++++++++++
 3 files changed, 324 insertions(+), 0 deletions(-)
 create mode 100644 drivers/watchdog/wm8350_wdt.c

diff --git a/drivers/watchdog/Kconfig b/drivers/watchdog/Kconfig
index 1a22fe7..b93e334 100644
--- a/drivers/watchdog/Kconfig
+++ b/drivers/watchdog/Kconfig
@@ -55,6 +55,13 @@ config SOFT_WATCHDOG
 	  To compile this driver as a module, choose M here: the
 	  module will be called softdog.
 
+config WM8350_WATCHDOG
+	tristate "WM8350 watchdog"
+	depends on MFD_WM8350
+	help
+	  Support for the watchdog in the WM8350 AudioPlus PMIC.  When
+	  the watchdog triggers the system will be reset.
+
 # ALPHA Architecture
 
 # ARM Architecture
diff --git a/drivers/watchdog/Makefile b/drivers/watchdog/Makefile
index e352bbb..c3b8db3 100644
--- a/drivers/watchdog/Makefile
+++ b/drivers/watchdog/Makefile
@@ -134,3 +134,4 @@ obj-$(CONFIG_WATCHDOG_CP1XXX)		+= cpwd.o
 
 # Architecture Independant
 obj-$(CONFIG_SOFT_WATCHDOG) += softdog.o
+obj-$(CONFIG_WM8350_WATCHDOG) += wm8350_wdt.o
diff --git a/drivers/watchdog/wm8350_wdt.c b/drivers/watchdog/wm8350_wdt.c
new file mode 100644
index 0000000..3cae199
--- /dev/null
+++ b/drivers/watchdog/wm8350_wdt.c
@@ -0,0 +1,316 @@
+/*
+ * Watchdog driver for the wm8350
+ *
+ * Copyright (C) 2007, 2008 Wolfson Microelectronics <linux@wolfsonmicro.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
+ */
+
+#include <linux/module.h>
+#include <linux/moduleparam.h>
+#include <linux/types.h>
+#include <linux/kernel.h>
+#include <linux/fs.h>
+#include <linux/miscdevice.h>
+#include <linux/platform_device.h>
+#include <linux/watchdog.h>
+#include <linux/uaccess.h>
+#include <linux/mfd/wm8350/core.h>
+
+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 long wm8350_wdt_users;
+static struct miscdevice wm8350_wdt_miscdev;
+static int wm8350_wdt_expect_close;
+
+static struct {
+	int time;  /* Seconds */
+	u16 val;   /* To be set in WM8350_SYSTEM_CONTROL_2 */
+} wm8350_wdt_cfgs[] = {
+	{ 1, 0x02 },
+	{ 2, 0x04 },
+	{ 4, 0x05 },
+};
+
+static struct wm8350 *get_wm8350(void)
+{
+	return dev_get_drvdata(wm8350_wdt_miscdev.parent);
+}
+
+static int wm8350_wdt_set_timeout(struct wm8350 *wm8350, u16 value)
+{
+	int ret;
+	u16 reg;
+
+	wm8350_reg_unlock(wm8350);
+
+	reg = wm8350_reg_read(wm8350, WM8350_SYSTEM_CONTROL_2);
+	reg &= ~WM8350_WDOG_TO_MASK;
+	reg |= value;
+	ret = wm8350_reg_write(wm8350, WM8350_SYSTEM_CONTROL_2, reg);
+
+	wm8350_reg_lock(wm8350);
+
+	return ret;
+}
+
+static int wm8350_wdt_start(struct wm8350 *wm8350)
+{
+	int ret;
+	u16 reg;
+
+	wm8350_reg_unlock(wm8350);
+
+	reg = wm8350_reg_read(wm8350, WM8350_SYSTEM_CONTROL_2);
+	reg &= ~WM8350_WDOG_MODE_MASK;
+	reg |= 0x20;
+	ret = wm8350_reg_write(wm8350, WM8350_SYSTEM_CONTROL_2, reg);
+
+	wm8350_reg_lock(wm8350);
+
+	return ret;
+}
+
+static int wm8350_wdt_stop(struct wm8350 *wm8350)
+{
+	int ret;
+	u16 reg;
+
+	wm8350_reg_unlock(wm8350);
+
+	reg = wm8350_reg_read(wm8350, WM8350_SYSTEM_CONTROL_2);
+	reg &= ~WM8350_WDOG_MODE_MASK;
+	ret = wm8350_reg_write(wm8350, WM8350_SYSTEM_CONTROL_2, reg);
+
+	wm8350_reg_lock(wm8350);
+
+	return ret;
+}
+
+static int wm8350_wdt_kick(struct wm8350 *wm8350)
+{
+	int ret;
+	u16 reg;
+
+	reg = wm8350_reg_read(wm8350, WM8350_SYSTEM_CONTROL_2);
+	ret = wm8350_reg_write(wm8350, WM8350_SYSTEM_CONTROL_2, reg);
+
+	return ret;
+}
+
+static int wm8350_wdt_open(struct inode *inode, struct file *file)
+{
+	struct wm8350 *wm8350 = get_wm8350();
+	int ret;
+
+	if (!wm8350) {
+		printk(KERN_CRIT "FNORD\n");
+		return -ENODEV;
+	}
+	if (test_and_set_bit(1, &wm8350_wdt_users))
+		return -EBUSY;
+
+	ret = wm8350_wdt_start(wm8350);
+	if (ret != 0)
+		return ret;
+
+	return nonseekable_open(inode, file);
+}
+
+static int wm8350_wdt_release(struct inode *inode, struct file *file)
+{
+	struct wm8350 *wm8350 = get_wm8350();
+
+	if (wm8350_wdt_expect_close)
+		wm8350_wdt_stop(wm8350);
+	else
+		dev_warn(wm8350->dev, "Watchdog device closed uncleanly\n");
+
+	clear_bit(1, &wm8350_wdt_users);
+
+	return 0;
+}
+
+static ssize_t wm8350_wdt_write(struct file *file,
+				const char __user *data, size_t count,
+				loff_t *ppos)
+{
+	struct wm8350 *wm8350 = get_wm8350();
+	size_t i;
+
+	if (count) {
+		wm8350_wdt_kick(wm8350);
+
+		if (!nowayout) {
+			/* In case it was set long ago */
+			wm8350_wdt_expect_close = 0;
+
+			/* scan to see whether or not we got the magic
+			   character */
+			for (i = 0; i != count; i++) {
+				char c;
+				if (get_user(c, data + i))
+					return -EFAULT;
+				if (c == 'V')
+					wm8350_wdt_expect_close = 42;
+			}
+		}
+	}
+	return count;
+}
+
+static struct watchdog_info ident = {
+	.options = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING | WDIOF_MAGICCLOSE,
+	.identity = "WM8350 Watchdog",
+};
+
+static int wm8350_wdt_ioctl(struct inode *inode, struct file *file,
+			    unsigned int cmd, unsigned long arg)
+{
+	struct wm8350 *wm8350 = get_wm8350();
+	int ret = -ENOTTY, time, i;
+	void __user *argp = (void __user *)arg;
+	int __user *p = argp;
+	u16 reg;
+
+	switch (cmd) {
+	case WDIOC_GETSUPPORT:
+		ret = copy_to_user(argp, &ident, sizeof(ident)) ? -EFAULT : 0;
+		break;
+
+	case WDIOC_GETSTATUS:
+		ret = put_user(0, p);
+		break;
+
+	case WDIOC_SETTIMEOUT:
+		ret = get_user(time, p);
+		if (ret)
+			break;
+
+		if (time == 0) {
+			if (nowayout)
+				ret = -EINVAL;
+			else
+				wm8350_wdt_stop(wm8350);
+			break;
+		}
+
+		for (i = 0; i < ARRAY_SIZE(wm8350_wdt_cfgs); i++)
+			if (wm8350_wdt_cfgs[i].time == time)
+				break;
+		if (i == ARRAY_SIZE(wm8350_wdt_cfgs))
+			ret = -EINVAL;
+		else
+			ret = wm8350_wdt_set_timeout(wm8350,
+						     wm8350_wdt_cfgs[i].val);
+		break;
+
+	case WDIOC_GETTIMEOUT:
+		reg = wm8350_reg_read(wm8350, WM8350_SYSTEM_CONTROL_2);
+		reg &= WM8350_WDOG_TO_MASK;
+		for (i = 0; i < ARRAY_SIZE(wm8350_wdt_cfgs); i++)
+			if (wm8350_wdt_cfgs[i].val == reg)
+				break;
+		if (i == ARRAY_SIZE(wm8350_wdt_cfgs)) {
+			dev_warn(wm8350->dev,
+				 "Unknown watchdog configuration: %x\n", reg);
+			ret = -EINVAL;
+		} else
+			ret = put_user(wm8350_wdt_cfgs[i].time, p);
+		break;
+
+	case WDIOC_KEEPALIVE:
+		ret = wm8350_wdt_kick(wm8350);
+		break;
+
+	case WDIOC_SETOPTIONS:
+	{
+		int options;
+
+		if (get_user(options, p))
+			return -EFAULT;
+
+		ret = -EINVAL;
+
+		/* Setting both simultaneously means at least one must fail */
+		if (options == WDIOS_DISABLECARD)
+			ret = wm8350_wdt_start(wm8350);
+
+		if (options == WDIOS_ENABLECARD)
+			ret = wm8350_wdt_stop(wm8350);
+	}
+
+	}
+
+	return ret;
+}
+
+static const struct file_operations wm8350_wdt_fops = {
+	.owner = THIS_MODULE,
+	.llseek = no_llseek,
+	.write = wm8350_wdt_write,
+	.ioctl = wm8350_wdt_ioctl,
+	.open = wm8350_wdt_open,
+	.release = wm8350_wdt_release,
+};
+
+static struct miscdevice wm8350_wdt_miscdev = {
+	.minor = WATCHDOG_MINOR,
+	.name = "watchdog",
+	.fops = &wm8350_wdt_fops,
+};
+
+static int wm8350_wdt_probe(struct platform_device *pdev)
+{
+	struct wm8350 *wm8350 = platform_get_drvdata(pdev);
+
+	if (!wm8350) {
+		dev_err(wm8350->dev, "No driver data supplied\n");
+		return -ENODEV;
+	}
+
+	/* Default to 4s timeout */
+	wm8350_wdt_set_timeout(wm8350, 0x05);
+
+	wm8350_wdt_miscdev.parent = &pdev->dev;
+
+	return misc_register(&wm8350_wdt_miscdev);
+}
+
+static int __exit wm8350_wdt_remove(struct platform_device *pdev)
+{
+	misc_deregister(&wm8350_wdt_miscdev);
+
+	return 0;
+}
+
+static struct platform_driver wm8350_wdt_driver = {
+	.probe = wm8350_wdt_probe,
+	.remove = wm8350_wdt_remove,
+	.driver = {
+		.name = "wm8350-wdt",
+	},
+};
+
+static int __init wm8350_wdt_init(void)
+{
+	return platform_driver_register(&wm8350_wdt_driver);
+}
+module_init(wm8350_wdt_init);
+
+static void __exit wm8350_wdt_exit(void)
+{
+	platform_driver_unregister(&wm8350_wdt_driver);
+}
+module_exit(wm8350_wdt_exit);
+
+MODULE_AUTHOR("Mark Brown");
+MODULE_DESCRIPTION("WM8350 Watchdog");
+MODULE_LICENSE("GPL");
+MODULE_ALIAS("platform:wm8350-wdt");
-- 
1.5.6.5

[PATCH] watchdog: Add support for the WM8350 watchdog

[Mark Brown]

This driver implements support for the watchdog functionality provided
by the Wolfson Microelectronics WM8350, a multi-function audio and
power management subsystem intended for use in embedded systems. It is
based on a driver originally written by Graeme Gregory, though it has
been extensively modified since then.

Use of a GPIO to kick the watchdog is not yet supported.

Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>
---

This patch depends on the WM8350 core support which is currently in the
process of being merged via the regulator tree - Wim, are you OK with
also merging this via there?

 drivers/mfd/wm8350-core.c       |    5 +
 drivers/watchdog/Kconfig        |    7 +
 drivers/watchdog/Makefile       |    1 +
 drivers/watchdog/wm8350_wdt.c   |  316 +++++++++++++++++++++++++++++++++++++++
 include/linux/mfd/wm8350/core.h |    2 +
 include/linux/mfd/wm8350/wdt.h  |    8 +-
 6 files changed, 338 insertions(+), 1 deletions(-)
 create mode 100644 drivers/watchdog/wm8350_wdt.c

diff --git a/drivers/mfd/wm8350-core.c b/drivers/mfd/wm8350-core.c
index cd1f76e..db354de 100644
--- a/drivers/mfd/wm8350-core.c
+++ b/drivers/mfd/wm8350-core.c
@@ -1234,6 +1234,8 @@ int wm8350_device_init(struct wm8350 *wm8350, int irq,
 
 	wm8350_reg_write(wm8350, WM8350_SYSTEM_INTERRUPTS_MASK, 0x0);
 
+	wm8350_client_dev_register(wm8350, "wm8350-wdt", &(wm8350->wdt.pdev));
+
 	return 0;
 
 err:
@@ -1250,6 +1252,9 @@ void wm8350_device_exit(struct wm8350 *wm8350)
 		if (wm8350->pmic.pdev[i] != NULL)
 			platform_device_unregister(wm8350->pmic.pdev[i]);
 
+	if (wm8350->wdt.pdev)
+		platform_device_unregister(wm8350->wdt.pdev);
+
 	free_irq(wm8350->chip_irq, wm8350);
 	flush_work(&wm8350->irq_work);
 	kfree(wm8350->reg_cache);
diff --git a/drivers/watchdog/Kconfig b/drivers/watchdog/Kconfig
index c510367..bf0d1bc 100644
--- a/drivers/watchdog/Kconfig
+++ b/drivers/watchdog/Kconfig
@@ -55,6 +55,13 @@ config SOFT_WATCHDOG
 	  To compile this driver as a module, choose M here: the
 	  module will be called softdog.
 
+config WM8350_WATCHDOG
+	tristate "WM8350 watchdog"
+	depends on MFD_WM8350
+	help
+	  Support for the watchdog in the WM8350 AudioPlus PMIC.  When
+	  the watchdog triggers the system will be reset.
+
 # ALPHA Architecture
 
 # ARM Architecture
diff --git a/drivers/watchdog/Makefile b/drivers/watchdog/Makefile
index e0ef123..e9d36c9 100644
--- a/drivers/watchdog/Makefile
+++ b/drivers/watchdog/Makefile
@@ -127,3 +127,4 @@ obj-$(CONFIG_SH_WDT) += shwdt.o
 
 # Architecture Independant
 obj-$(CONFIG_SOFT_WATCHDOG) += softdog.o
+obj-$(CONFIG_WM8350_WATCHDOG) += wm8350_wdt.o
diff --git a/drivers/watchdog/wm8350_wdt.c b/drivers/watchdog/wm8350_wdt.c
new file mode 100644
index 0000000..3cae199
--- /dev/null
+++ b/drivers/watchdog/wm8350_wdt.c
@@ -0,0 +1,316 @@
+/*
+ * Watchdog driver for the wm8350
+ *
+ * Copyright (C) 2007, 2008 Wolfson Microelectronics <linux@wolfsonmicro.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
+ */
+
+#include <linux/module.h>
+#include <linux/moduleparam.h>
+#include <linux/types.h>
+#include <linux/kernel.h>
+#include <linux/fs.h>
+#include <linux/miscdevice.h>
+#include <linux/platform_device.h>
+#include <linux/watchdog.h>
+#include <linux/uaccess.h>
+#include <linux/mfd/wm8350/core.h>
+
+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 long wm8350_wdt_users;
+static struct miscdevice wm8350_wdt_miscdev;
+static int wm8350_wdt_expect_close;
+
+static struct {
+	int time;  /* Seconds */
+	u16 val;   /* To be set in WM8350_SYSTEM_CONTROL_2 */
+} wm8350_wdt_cfgs[] = {
+	{ 1, 0x02 },
+	{ 2, 0x04 },
+	{ 4, 0x05 },
+};
+
+static struct wm8350 *get_wm8350(void)
+{
+	return dev_get_drvdata(wm8350_wdt_miscdev.parent);
+}
+
+static int wm8350_wdt_set_timeout(struct wm8350 *wm8350, u16 value)
+{
+	int ret;
+	u16 reg;
+
+	wm8350_reg_unlock(wm8350);
+
+	reg = wm8350_reg_read(wm8350, WM8350_SYSTEM_CONTROL_2);
+	reg &= ~WM8350_WDOG_TO_MASK;
+	reg |= value;
+	ret = wm8350_reg_write(wm8350, WM8350_SYSTEM_CONTROL_2, reg);
+
+	wm8350_reg_lock(wm8350);
+
+	return ret;
+}
+
+static int wm8350_wdt_start(struct wm8350 *wm8350)
+{
+	int ret;
+	u16 reg;
+
+	wm8350_reg_unlock(wm8350);
+
+	reg = wm8350_reg_read(wm8350, WM8350_SYSTEM_CONTROL_2);
+	reg &= ~WM8350_WDOG_MODE_MASK;
+	reg |= 0x20;
+	ret = wm8350_reg_write(wm8350, WM8350_SYSTEM_CONTROL_2, reg);
+
+	wm8350_reg_lock(wm8350);
+
+	return ret;
+}
+
+static int wm8350_wdt_stop(struct wm8350 *wm8350)
+{
+	int ret;
+	u16 reg;
+
+	wm8350_reg_unlock(wm8350);
+
+	reg = wm8350_reg_read(wm8350, WM8350_SYSTEM_CONTROL_2);
+	reg &= ~WM8350_WDOG_MODE_MASK;
+	ret = wm8350_reg_write(wm8350, WM8350_SYSTEM_CONTROL_2, reg);
+
+	wm8350_reg_lock(wm8350);
+
+	return ret;
+}
+
+static int wm8350_wdt_kick(struct wm8350 *wm8350)
+{
+	int ret;
+	u16 reg;
+
+	reg = wm8350_reg_read(wm8350, WM8350_SYSTEM_CONTROL_2);
+	ret = wm8350_reg_write(wm8350, WM8350_SYSTEM_CONTROL_2, reg);
+
+	return ret;
+}
+
+static int wm8350_wdt_open(struct inode *inode, struct file *file)
+{
+	struct wm8350 *wm8350 = get_wm8350();
+	int ret;
+
+	if (!wm8350) {
+		printk(KERN_CRIT "FNORD\n");
+		return -ENODEV;
+	}
+	if (test_and_set_bit(1, &wm8350_wdt_users))
+		return -EBUSY;
+
+	ret = wm8350_wdt_start(wm8350);
+	if (ret != 0)
+		return ret;
+
+	return nonseekable_open(inode, file);
+}
+
+static int wm8350_wdt_release(struct inode *inode, struct file *file)
+{
+	struct wm8350 *wm8350 = get_wm8350();
+
+	if (wm8350_wdt_expect_close)
+		wm8350_wdt_stop(wm8350);
+	else
+		dev_warn(wm8350->dev, "Watchdog device closed uncleanly\n");
+
+	clear_bit(1, &wm8350_wdt_users);
+
+	return 0;
+}
+
+static ssize_t wm8350_wdt_write(struct file *file,
+				const char __user *data, size_t count,
+				loff_t *ppos)
+{
+	struct wm8350 *wm8350 = get_wm8350();
+	size_t i;
+
+	if (count) {
+		wm8350_wdt_kick(wm8350);
+
+		if (!nowayout) {
+			/* In case it was set long ago */
+			wm8350_wdt_expect_close = 0;
+
+			/* scan to see whether or not we got the magic
+			   character */
+			for (i = 0; i != count; i++) {
+				char c;
+				if (get_user(c, data + i))
+					return -EFAULT;
+				if (c == 'V')
+					wm8350_wdt_expect_close = 42;
+			}
+		}
+	}
+	return count;
+}
+
+static struct watchdog_info ident = {
+	.options = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING | WDIOF_MAGICCLOSE,
+	.identity = "WM8350 Watchdog",
+};
+
+static int wm8350_wdt_ioctl(struct inode *inode, struct file *file,
+			    unsigned int cmd, unsigned long arg)
+{
+	struct wm8350 *wm8350 = get_wm8350();
+	int ret = -ENOTTY, time, i;
+	void __user *argp = (void __user *)arg;
+	int __user *p = argp;
+	u16 reg;
+
+	switch (cmd) {
+	case WDIOC_GETSUPPORT:
+		ret = copy_to_user(argp, &ident, sizeof(ident)) ? -EFAULT : 0;
+		break;
+
+	case WDIOC_GETSTATUS:
+		ret = put_user(0, p);
+		break;
+
+	case WDIOC_SETTIMEOUT:
+		ret = get_user(time, p);
+		if (ret)
+			break;
+
+		if (time == 0) {
+			if (nowayout)
+				ret = -EINVAL;
+			else
+				wm8350_wdt_stop(wm8350);
+			break;
+		}
+
+		for (i = 0; i < ARRAY_SIZE(wm8350_wdt_cfgs); i++)
+			if (wm8350_wdt_cfgs[i].time == time)
+				break;
+		if (i == ARRAY_SIZE(wm8350_wdt_cfgs))
+			ret = -EINVAL;
+		else
+			ret = wm8350_wdt_set_timeout(wm8350,
+						     wm8350_wdt_cfgs[i].val);
+		break;
+
+	case WDIOC_GETTIMEOUT:
+		reg = wm8350_reg_read(wm8350, WM8350_SYSTEM_CONTROL_2);
+		reg &= WM8350_WDOG_TO_MASK;
+		for (i = 0; i < ARRAY_SIZE(wm8350_wdt_cfgs); i++)
+			if (wm8350_wdt_cfgs[i].val == reg)
+				break;
+		if (i == ARRAY_SIZE(wm8350_wdt_cfgs)) {
+			dev_warn(wm8350->dev,
+				 "Unknown watchdog configuration: %x\n", reg);
+			ret = -EINVAL;
+		} else
+			ret = put_user(wm8350_wdt_cfgs[i].time, p);
+		break;
+
+	case WDIOC_KEEPALIVE:
+		ret = wm8350_wdt_kick(wm8350);
+		break;
+
+	case WDIOC_SETOPTIONS:
+	{
+		int options;
+
+		if (get_user(options, p))
+			return -EFAULT;
+
+		ret = -EINVAL;
+
+		/* Setting both simultaneously means at least one must fail */
+		if (options == WDIOS_DISABLECARD)
+			ret = wm8350_wdt_start(wm8350);
+
+		if (options == WDIOS_ENABLECARD)
+			ret = wm8350_wdt_stop(wm8350);
+	}
+
+	}
+
+	return ret;
+}
+
+static const struct file_operations wm8350_wdt_fops = {
+	.owner = THIS_MODULE,
+	.llseek = no_llseek,
+	.write = wm8350_wdt_write,
+	.ioctl = wm8350_wdt_ioctl,
+	.open = wm8350_wdt_open,
+	.release = wm8350_wdt_release,
+};
+
+static struct miscdevice wm8350_wdt_miscdev = {
+	.minor = WATCHDOG_MINOR,
+	.name = "watchdog",
+	.fops = &wm8350_wdt_fops,
+};
+
+static int wm8350_wdt_probe(struct platform_device *pdev)
+{
+	struct wm8350 *wm8350 = platform_get_drvdata(pdev);
+
+	if (!wm8350) {
+		dev_err(wm8350->dev, "No driver data supplied\n");
+		return -ENODEV;
+	}
+
+	/* Default to 4s timeout */
+	wm8350_wdt_set_timeout(wm8350, 0x05);
+
+	wm8350_wdt_miscdev.parent = &pdev->dev;
+
+	return misc_register(&wm8350_wdt_miscdev);
+}
+
+static int __exit wm8350_wdt_remove(struct platform_device *pdev)
+{
+	misc_deregister(&wm8350_wdt_miscdev);
+
+	return 0;
+}
+
+static struct platform_driver wm8350_wdt_driver = {
+	.probe = wm8350_wdt_probe,
+	.remove = wm8350_wdt_remove,
+	.driver = {
+		.name = "wm8350-wdt",
+	},
+};
+
+static int __init wm8350_wdt_init(void)
+{
+	return platform_driver_register(&wm8350_wdt_driver);
+}
+module_init(wm8350_wdt_init);
+
+static void __exit wm8350_wdt_exit(void)
+{
+	platform_driver_unregister(&wm8350_wdt_driver);
+}
+module_exit(wm8350_wdt_exit);
+
+MODULE_AUTHOR("Mark Brown");
+MODULE_DESCRIPTION("WM8350 Watchdog");
+MODULE_LICENSE("GPL");
+MODULE_ALIAS("platform:wm8350-wdt");
diff --git a/include/linux/mfd/wm8350/core.h b/include/linux/mfd/wm8350/core.h
index 348101c..5df704f 100644
--- a/include/linux/mfd/wm8350/core.h
+++ b/include/linux/mfd/wm8350/core.h
@@ -18,6 +18,7 @@
 #include <linux/workqueue.h>
 
 #include <linux/mfd/wm8350/pmic.h>
+#include <linux/mfd/wm8350/wdt.h>
 
 /*
  * Register values.
@@ -575,6 +576,7 @@ struct wm8350 {
 
 	/* Client devices */
 	struct wm8350_pmic pmic;
+	struct wm8350_wdt wdt;
 };
 
 /**
diff --git a/include/linux/mfd/wm8350/wdt.h b/include/linux/mfd/wm8350/wdt.h
index 72fc9f5..f6135b5 100644
--- a/include/linux/mfd/wm8350/wdt.h
+++ b/include/linux/mfd/wm8350/wdt.h
@@ -1,7 +1,7 @@
 /*
  * wdt.h  --  Watchdog Driver for Wolfson WM8350 PMIC
  *
- * Copyright 2007 Wolfson Microelectronics PLC
+ * Copyright 2007, 2008 Wolfson Microelectronics PLC
  *
  *  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
@@ -12,6 +12,8 @@
 #ifndef __LINUX_MFD_WM8350_WDT_H_
 #define __LINUX_MFD_WM8350_WDT_H_
 
+#include <linux/platform_device.h>
+
 #define WM8350_WDOG_HIB_MODE                    0x0080
 #define WM8350_WDOG_DEBUG                       0x0040
 #define WM8350_WDOG_MODE_MASK                   0x0030
@@ -19,4 +21,8 @@
 
 #define WM8350_IRQ_SYS_WDOG_TO			24
 
+struct wm8350_wdt {
+	struct platform_device *pdev;
+};
+
 #endif
-- 
1.5.6.5