[WATCHDOG] Add support for WM831x watchdog

The WM831x series of devices provide a watchdog with configurable
behaviour on timer expiry.

Currently this driver support refreshes via a register or GPIO line and
autonomous refreshes from a hardware source (eg, a clock).

Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>
Signed-off-by: Wim Van Sebroeck <wim@iguana.be>

3 files changed, 449 insertions, 0 deletions

diff --git a/drivers/watchdog/Kconfig b/drivers/watchdog/Kconfig
index 3229889..ff3eb8f 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 WM831X_WATCHDOG
+	tristate "WM831x watchdog"
+	depends on MFD_WM831X
+	help
+	  Support for the watchdog in the WM831x AudioPlus PMICs.  When
+	  the watchdog triggers the system will be reset.
+
 config WM8350_WATCHDOG
 	tristate "WM8350 watchdog"
 	depends on MFD_WM8350
diff --git a/drivers/watchdog/Makefile b/drivers/watchdog/Makefile
index e1784a6..348b3b8 100644
--- a/drivers/watchdog/Makefile
+++ b/drivers/watchdog/Makefile
@@ -141,5 +141,6 @@ obj-$(CONFIG_WATCHDOG_CP1XXX)		+= cpwd.o
 # XTENSA Architecture
 
 # Architecture Independant
+obj-$(CONFIG_WM831X_WATCHDOG) += wm831x_wdt.o
 obj-$(CONFIG_WM8350_WATCHDOG) += wm8350_wdt.o
 obj-$(CONFIG_SOFT_WATCHDOG) += softdog.o
diff --git a/drivers/watchdog/wm831x_wdt.c b/drivers/watchdog/wm831x_wdt.c
new file mode 100644
index 0000000..775bcd8
--- /dev/null
+++ b/drivers/watchdog/wm831x_wdt.c
@@ -0,0 +1,441 @@
+/*
+ * Watchdog driver for the wm831x PMICs
+ *
+ * Copyright (C) 2009 Wolfson Microelectronics
+ *
+ * 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/gpio.h>
+
+#include <linux/mfd/wm831x/core.h>
+#include <linux/mfd/wm831x/pdata.h>
+#include <linux/mfd/wm831x/watchdog.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 wm831x_wdt_users;
+static struct miscdevice wm831x_wdt_miscdev;
+static int wm831x_wdt_expect_close;
+static DEFINE_MUTEX(wdt_mutex);
+static struct wm831x *wm831x;
+static unsigned int update_gpio;
+static unsigned int update_state;
+
+/* We can't use the sub-second values here but they're included
+ * for completeness.  */
+static struct {
+	int time;  /* Seconds */
+	u16 val;   /* WDOG_TO value */
+} wm831x_wdt_cfgs[] = {
+	{  1, 2 },
+	{  2, 3 },
+	{  4, 4 },
+	{  8, 5 },
+	{ 16, 6 },
+	{ 32, 7 },
+	{ 33, 7 },  /* Actually 32.768s so include both, others round down */
+};
+
+static int wm831x_wdt_set_timeout(struct wm831x *wm831x, u16 value)
+{
+	int ret;
+
+	mutex_lock(&wdt_mutex);
+
+	ret = wm831x_reg_unlock(wm831x);
+	if (ret == 0) {
+		ret = wm831x_set_bits(wm831x, WM831X_WATCHDOG,
+				      WM831X_WDOG_TO_MASK, value);
+		wm831x_reg_lock(wm831x);
+	} else {
+		dev_err(wm831x->dev, "Failed to unlock security key: %d\n",
+			ret);
+	}
+
+	mutex_unlock(&wdt_mutex);
+
+	return ret;
+}
+
+static int wm831x_wdt_start(struct wm831x *wm831x)
+{
+	int ret;
+
+	mutex_lock(&wdt_mutex);
+
+	ret = wm831x_reg_unlock(wm831x);
+	if (ret == 0) {
+		ret = wm831x_set_bits(wm831x, WM831X_WATCHDOG,
+				      WM831X_WDOG_ENA, WM831X_WDOG_ENA);
+		wm831x_reg_lock(wm831x);
+	} else {
+		dev_err(wm831x->dev, "Failed to unlock security key: %d\n",
+			ret);
+	}
+
+	mutex_unlock(&wdt_mutex);
+
+	return ret;
+}
+
+static int wm831x_wdt_stop(struct wm831x *wm831x)
+{
+	int ret;
+
+	mutex_lock(&wdt_mutex);
+
+	ret = wm831x_reg_unlock(wm831x);
+	if (ret == 0) {
+		ret = wm831x_set_bits(wm831x, WM831X_WATCHDOG,
+				      WM831X_WDOG_ENA, 0);
+		wm831x_reg_lock(wm831x);
+	} else {
+		dev_err(wm831x->dev, "Failed to unlock security key: %d\n",
+			ret);
+	}
+
+	mutex_unlock(&wdt_mutex);
+
+	return ret;
+}
+
+static int wm831x_wdt_kick(struct wm831x *wm831x)
+{
+	int ret;
+	u16 reg;
+
+	mutex_lock(&wdt_mutex);
+
+	if (update_gpio) {
+		gpio_set_value_cansleep(update_gpio, update_state);
+		update_state = !update_state;
+		ret = 0;
+		goto out;
+	}
+
+
+	reg = wm831x_reg_read(wm831x, WM831X_WATCHDOG);
+
+	if (!(reg & WM831X_WDOG_RST_SRC)) {
+		dev_err(wm831x->dev, "Hardware watchdog update unsupported\n");
+		ret = -EINVAL;
+		goto out;
+	}
+
+	reg |= WM831X_WDOG_RESET;
+
+	ret = wm831x_reg_unlock(wm831x);
+	if (ret == 0) {
+		ret = wm831x_reg_write(wm831x, WM831X_WATCHDOG, reg);
+		wm831x_reg_lock(wm831x);
+	} else {
+		dev_err(wm831x->dev, "Failed to unlock security key: %d\n",
+			ret);
+	}
+
+out:
+	mutex_unlock(&wdt_mutex);
+
+	return ret;
+}
+
+static int wm831x_wdt_open(struct inode *inode, struct file *file)
+{
+	int ret;
+
+	if (!wm831x)
+		return -ENODEV;
+
+	if (test_and_set_bit(0, &wm831x_wdt_users))
+		return -EBUSY;
+
+	ret = wm831x_wdt_start(wm831x);
+	if (ret != 0)
+		return ret;
+
+	return nonseekable_open(inode, file);
+}
+
+static int wm831x_wdt_release(struct inode *inode, struct file *file)
+{
+	if (wm831x_wdt_expect_close)
+		wm831x_wdt_stop(wm831x);
+	else {
+		dev_warn(wm831x->dev, "Watchdog device closed uncleanly\n");
+		wm831x_wdt_kick(wm831x);
+	}
+
+	clear_bit(0, &wm831x_wdt_users);
+
+	return 0;
+}
+
+static ssize_t wm831x_wdt_write(struct file *file,
+				const char __user *data, size_t count,
+				loff_t *ppos)
+{
+	size_t i;
+
+	if (count) {
+		wm831x_wdt_kick(wm831x);
+
+		if (!nowayout) {
+			/* In case it was set long ago */
+			wm831x_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')
+					wm831x_wdt_expect_close = 42;
+			}
+		}
+	}
+	return count;
+}
+
+static struct watchdog_info ident = {
+	.options = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING | WDIOF_MAGICCLOSE,
+	.identity = "WM831x Watchdog",
+};
+
+static long wm831x_wdt_ioctl(struct file *file, unsigned int cmd,
+			     unsigned long arg)
+{
+	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_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 = wm831x_wdt_start(wm831x);
+
+		if (options == WDIOS_ENABLECARD)
+			ret = wm831x_wdt_stop(wm831x);
+		break;
+	}
+
+	case WDIOC_KEEPALIVE:
+		ret = wm831x_wdt_kick(wm831x);
+		break;
+
+	case WDIOC_SETTIMEOUT:
+		ret = get_user(time, p);
+		if (ret)
+			break;
+
+		if (time == 0) {
+			if (nowayout)
+				ret = -EINVAL;
+			else
+				wm831x_wdt_stop(wm831x);
+			break;
+		}
+
+		for (i = 0; i < ARRAY_SIZE(wm831x_wdt_cfgs); i++)
+			if (wm831x_wdt_cfgs[i].time == time)
+				break;
+		if (i == ARRAY_SIZE(wm831x_wdt_cfgs))
+			ret = -EINVAL;
+		else
+			ret = wm831x_wdt_set_timeout(wm831x,
+						     wm831x_wdt_cfgs[i].val);
+		break;
+
+	case WDIOC_GETTIMEOUT:
+		reg = wm831x_reg_read(wm831x, WM831X_WATCHDOG);
+		reg &= WM831X_WDOG_TO_MASK;
+		for (i = 0; i < ARRAY_SIZE(wm831x_wdt_cfgs); i++)
+			if (wm831x_wdt_cfgs[i].val == reg)
+				break;
+		if (i == ARRAY_SIZE(wm831x_wdt_cfgs)) {
+			dev_warn(wm831x->dev,
+				 "Unknown watchdog configuration: %x\n", reg);
+			ret = -EINVAL;
+		} else
+			ret = put_user(wm831x_wdt_cfgs[i].time, p);
+
+	}
+
+	return ret;
+}
+
+static const struct file_operations wm831x_wdt_fops = {
+	.owner = THIS_MODULE,
+	.llseek = no_llseek,
+	.write = wm831x_wdt_write,
+	.unlocked_ioctl = wm831x_wdt_ioctl,
+	.open = wm831x_wdt_open,
+	.release = wm831x_wdt_release,
+};
+
+static struct miscdevice wm831x_wdt_miscdev = {
+	.minor = WATCHDOG_MINOR,
+	.name = "watchdog",
+	.fops = &wm831x_wdt_fops,
+};
+
+static int __devinit wm831x_wdt_probe(struct platform_device *pdev)
+{
+	struct wm831x_pdata *chip_pdata;
+	struct wm831x_watchdog_pdata *pdata;
+	int reg, ret;
+
+	wm831x = dev_get_drvdata(pdev->dev.parent);
+
+	ret = wm831x_reg_read(wm831x, WM831X_WATCHDOG);
+	if (ret < 0) {
+		dev_err(wm831x->dev, "Failed to read watchdog status: %d\n",
+			ret);
+		goto err;
+	}
+	reg = ret;
+
+	if (reg & WM831X_WDOG_DEBUG)
+		dev_warn(wm831x->dev, "Watchdog is paused\n");
+
+	/* Apply any configuration */
+	if (pdev->dev.parent->platform_data) {
+		chip_pdata = pdev->dev.parent->platform_data;
+		pdata = chip_pdata->watchdog;
+	} else {
+		pdata = NULL;
+	}
+
+	if (pdata) {
+		reg &= ~(WM831X_WDOG_SECACT_MASK | WM831X_WDOG_PRIMACT_MASK |
+			 WM831X_WDOG_RST_SRC);
+
+		reg |= pdata->primary << WM831X_WDOG_PRIMACT_SHIFT;
+		reg |= pdata->secondary << WM831X_WDOG_SECACT_SHIFT;
+		reg |= pdata->software << WM831X_WDOG_RST_SRC_SHIFT;
+
+		if (pdata->update_gpio) {
+			ret = gpio_request(pdata->update_gpio,
+					   "Watchdog update");
+			if (ret < 0) {
+				dev_err(wm831x->dev,
+					"Failed to request update GPIO: %d\n",
+					ret);
+				goto err;
+			}
+
+			ret = gpio_direction_output(pdata->update_gpio, 0);
+			if (ret != 0) {
+				dev_err(wm831x->dev,
+					"gpio_direction_output returned: %d\n",
+					ret);
+				goto err_gpio;
+			}
+
+			update_gpio = pdata->update_gpio;
+
+			/* Make sure the watchdog takes hardware updates */
+			reg |= WM831X_WDOG_RST_SRC;
+		}
+
+		ret = wm831x_reg_unlock(wm831x);
+		if (ret == 0) {
+			ret = wm831x_reg_write(wm831x, WM831X_WATCHDOG, reg);
+			wm831x_reg_lock(wm831x);
+		} else {
+			dev_err(wm831x->dev,
+				"Failed to unlock security key: %d\n", ret);
+			goto err_gpio;
+		}
+	}
+
+	wm831x_wdt_miscdev.parent = &pdev->dev;
+
+	ret = misc_register(&wm831x_wdt_miscdev);
+	if (ret != 0) {
+		dev_err(wm831x->dev, "Failed to register miscdev: %d\n", ret);
+		goto err_gpio;
+	}
+
+	return 0;
+
+err_gpio:
+	if (update_gpio) {
+		gpio_free(update_gpio);
+		update_gpio = 0;
+	}
+err:
+	return ret;
+}
+
+static int __devexit wm831x_wdt_remove(struct platform_device *pdev)
+{
+	if (update_gpio) {
+		gpio_free(update_gpio);
+		update_gpio = 0;
+	}
+
+	misc_deregister(&wm831x_wdt_miscdev);
+
+	return 0;
+}
+
+static struct platform_driver wm831x_wdt_driver = {
+	.probe = wm831x_wdt_probe,
+	.remove = __devexit_p(wm831x_wdt_remove),
+	.driver = {
+		.name = "wm831x-watchdog",
+	},
+};
+
+static int __init wm831x_wdt_init(void)
+{
+	return platform_driver_register(&wm831x_wdt_driver);
+}
+module_init(wm831x_wdt_init);
+
+static void __exit wm831x_wdt_exit(void)
+{
+	platform_driver_unregister(&wm831x_wdt_driver);
+}
+module_exit(wm831x_wdt_exit);
+
+MODULE_AUTHOR("Mark Brown");
+MODULE_DESCRIPTION("WM831x Watchdog");
+MODULE_LICENSE("GPL");
+MODULE_ALIAS("platform:wm831x-watchdog");