[WATCHDOG] Add support for the WM8350 watchdog

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>
Signed-off-by: Wim Van Sebroeck <wim@iguana.be>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

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

drivers/watchdog/Makefile

@@ -134,4 +134,5 @@ obj-$(CONFIG_WATCHDOG_CP1XXX)		+= cpwd.o
 # XTENSA Architecture
 
 # Architecture Independant
+obj-$(CONFIG_WM8350_WATCHDOG) += wm8350_wdt.o
 obj-$(CONFIG_SOFT_WATCHDOG) += softdog.o

drivers/watchdog/wm8350_wdt.c

+/*
+ * 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_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);
+		break;
+	}
+
+	case WDIOC_KEEPALIVE:
+		ret = wm8350_wdt_kick(wm8350);
+		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);
+
+	}
+
+	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");