[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>

3 files changed, 337 insertions, 0 deletions

diff --git a/drivers/watchdog/Kconfig b/drivers/watchdog/Kconfig
index 81f7021b3816..ec68c741b564 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 0cd47867b194..c19b866f5ed1 100644
--- a/drivers/watchdog/Makefile
+++ b/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
diff --git a/drivers/watchdog/wm8350_wdt.c b/drivers/watchdog/wm8350_wdt.c
new file mode 100644
index 000000000000..2bc0d4d4b415
--- /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_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");