[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 3229889c3591..ff3eb8ff6bd7 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 e1784a6208a7..348b3b862c99 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 000000000000..775bcd807f31
--- /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");