hwmon: (w83793) Add watchdog functionality

Add watchdog functionality to the Winbond W83793 driver.

Signed-off-by: Sven Anders <anders@anduras.de>
Acked-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Jean Delvare <khali@linux-fr.org>

2 files changed, 481 insertions, 4 deletions

diff --git a/drivers/hwmon/Kconfig b/drivers/hwmon/Kconfig
index 9234c2e2c7d9..cdfb0637f247 100644
--- a/drivers/hwmon/Kconfig
+++ b/drivers/hwmon/Kconfig
@@ -910,7 +910,8 @@ config SENSORS_W83793
         select HWMON_VID
         help
           If you say yes here you get support for the Winbond W83793
-          hardware monitoring chip.
+          hardware monitoring chip, including support for the integrated
+          watchdog.
 
           This driver can also be built as a module.  If so, the module
           will be called w83793.
diff --git a/drivers/hwmon/w83793.c b/drivers/hwmon/w83793.c
index 9a2022b67495..9de81a4c15a2 100644
--- a/drivers/hwmon/w83793.c
+++ b/drivers/hwmon/w83793.c
@@ -3,6 +3,10 @@
     Copyright (C) 2006 Winbond Electronics Corp.
                   Yuan Mu
                   Rudolf Marek <r.marek@assembler.cz>
+    Copyright (C) 2009-2010 Sven Anders <anders@anduras.de>, ANDURAS AG.
+                  Watchdog driver part
+                  (Based partially on fschmd driver,
+                   Copyright 2007-2008 by Hans de Goede)
 
     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
@@ -35,6 +39,16 @@
 #include <linux/hwmon-sysfs.h>
 #include <linux/err.h>
 #include <linux/mutex.h>
+#include <linux/fs.h>
+#include <linux/watchdog.h>
+#include <linux/miscdevice.h>
+#include <linux/uaccess.h>
+#include <linux/kref.h>
+#include <linux/notifier.h>
+#include <linux/reboot.h>
+
+/* Default values */
+#define WATCHDOG_TIMEOUT 2      /* 2 minute default timeout */
 
 /* Addresses to scan */
 static const unsigned short normal_i2c[] = { 0x2c, 0x2d, 0x2e, 0x2f,
@@ -51,6 +65,18 @@ static int reset;
 module_param(reset, bool, 0);
 MODULE_PARM_DESC(reset, "Set to 1 to reset chip, not recommended");
 
+static int timeout = WATCHDOG_TIMEOUT;  /* default timeout in minutes */
+module_param(timeout, int, 0);
+MODULE_PARM_DESC(timeout,
+        "Watchdog timeout in minutes. 2<= timeout <=255 (default="
+                                __MODULE_STRING(WATCHDOG_TIMEOUT) ")");
+
+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) ")");
+
 /*
    Address 0x00, 0x0d, 0x0e, 0x0f in all three banks are reserved
    as ID, Bank Select registers
@@ -72,6 +98,11 @@ MODULE_PARM_DESC(reset, "Set to 1 to reset chip, not recommended");
 #define W83793_REG_VID_LATCHB           0x08
 #define W83793_REG_VID_CTRL             0x59
 
+#define W83793_REG_WDT_LOCK             0x01
+#define W83793_REG_WDT_ENABLE           0x02
+#define W83793_REG_WDT_STATUS           0x03
+#define W83793_REG_WDT_TIMEOUT          0x04
+
 static u16 W83793_REG_TEMP_MODE[2] = { 0x5e, 0x5f };
 
 #define TEMP_READ       0
@@ -223,8 +254,37 @@ struct w83793_data {
         u8 tolerance[3];        /* Temp tolerance(Smart Fan I/II) */
         u8 sf2_pwm[6][7];       /* Smart FanII: Fan duty cycle */
         u8 sf2_temp[6][7];      /* Smart FanII: Temp level point */
+
+        /* watchdog */
+        struct i2c_client *client;
+        struct mutex watchdog_lock;
+        struct list_head list; /* member of the watchdog_data_list */
+        struct kref kref;
+        struct miscdevice watchdog_miscdev;
+        unsigned long watchdog_is_open;
+        char watchdog_expect_close;
+        char watchdog_name[10]; /* must be unique to avoid sysfs conflict */
+        unsigned int watchdog_caused_reboot;
+        int watchdog_timeout; /* watchdog timeout in minutes */
 };
 
+/* Somewhat ugly :( global data pointer list with all devices, so that
+   we can find our device data as when using misc_register. There is no
+   other method to get to one's device data from the open file-op and
+   for usage in the reboot notifier callback. */
+static LIST_HEAD(watchdog_data_list);
+
+/* Note this lock not only protect list access, but also data.kref access */
+static DEFINE_MUTEX(watchdog_data_mutex);
+
+/* Release our data struct when we're detached from the i2c client *and* all
+   references to our watchdog device are released */
+static void w83793_release_resources(struct kref *ref)
+{
+        struct w83793_data *data = container_of(ref, struct w83793_data, kref);
+        kfree(data);
+}
+
 static u8 w83793_read_value(struct i2c_client *client, u16 reg);
 static int w83793_write_value(struct i2c_client *client, u16 reg, u8 value);
 static int w83793_probe(struct i2c_client *client,
@@ -1063,14 +1123,349 @@ static void w83793_init_client(struct i2c_client *client)
         /* Start monitoring */
         w83793_write_value(client, W83793_REG_CONFIG,
                            w83793_read_value(client, W83793_REG_CONFIG) | 0x01);
+}
+
+/*
+ * Watchdog routines
+ */
+
+static int watchdog_set_timeout(struct w83793_data *data, int timeout)
+{
+        int ret, mtimeout;
+
+        mtimeout = DIV_ROUND_UP(timeout, 60);
+
+        if (mtimeout > 255)
+                return -EINVAL;
+
+        mutex_lock(&data->watchdog_lock);
+        if (!data->client) {
+                ret = -ENODEV;
+                goto leave;
+        }
+
+        data->watchdog_timeout = mtimeout;
+
+        /* Set Timeout value (in Minutes) */
+        w83793_write_value(data->client, W83793_REG_WDT_TIMEOUT,
+                           data->watchdog_timeout);
+
+        ret = mtimeout * 60;
+
+leave:
+        mutex_unlock(&data->watchdog_lock);
+        return ret;
+}
+
+static int watchdog_get_timeout(struct w83793_data *data)
+{
+        int timeout;
+
+        mutex_lock(&data->watchdog_lock);
+        timeout = data->watchdog_timeout * 60;
+        mutex_unlock(&data->watchdog_lock);
+
+        return timeout;
+}
+
+static int watchdog_trigger(struct w83793_data *data)
+{
+        int ret = 0;
+
+        mutex_lock(&data->watchdog_lock);
+        if (!data->client) {
+                ret = -ENODEV;
+                goto leave;
+        }
+
+        /* Set Timeout value (in Minutes) */
+        w83793_write_value(data->client, W83793_REG_WDT_TIMEOUT,
+                           data->watchdog_timeout);
+
+leave:
+        mutex_unlock(&data->watchdog_lock);
+        return ret;
+}
+
+static int watchdog_enable(struct w83793_data *data)
+{
+        int ret = 0;
+
+        mutex_lock(&data->watchdog_lock);
+        if (!data->client) {
+                ret = -ENODEV;
+                goto leave;
+        }
+
+        /* Set initial timeout */
+        w83793_write_value(data->client, W83793_REG_WDT_TIMEOUT,
+                           data->watchdog_timeout);
+
+        /* Enable Soft Watchdog */
+        w83793_write_value(data->client, W83793_REG_WDT_LOCK, 0x55);
+
+leave:
+        mutex_unlock(&data->watchdog_lock);
+        return ret;
+}
+
+static int watchdog_disable(struct w83793_data *data)
+{
+        int ret = 0;
+
+        mutex_lock(&data->watchdog_lock);
+        if (!data->client) {
+                ret = -ENODEV;
+                goto leave;
+        }
+
+        /* Disable Soft Watchdog */
+        w83793_write_value(data->client, W83793_REG_WDT_LOCK, 0xAA);
+
+leave:
+        mutex_unlock(&data->watchdog_lock);
+        return ret;
+}
+
+static int watchdog_open(struct inode *inode, struct file *filp)
+{
+        struct w83793_data *pos, *data = NULL;
+        int watchdog_is_open;
+
+        /* We get called from drivers/char/misc.c with misc_mtx hold, and we
+           call misc_register() from  w83793_probe() with watchdog_data_mutex
+           hold, as misc_register() takes the misc_mtx lock, this is a possible
+           deadlock, so we use mutex_trylock here. */
+        if (!mutex_trylock(&watchdog_data_mutex))
+                return -ERESTARTSYS;
+        list_for_each_entry(pos, &watchdog_data_list, list) {
+                if (pos->watchdog_miscdev.minor == iminor(inode)) {
+                        data = pos;
+                        break;
+                }
+        }
+
+        /* Check, if device is already open */
+        watchdog_is_open = test_and_set_bit(0, &data->watchdog_is_open);
+
+        /* Increase data reference counter (if not already done).
+           Note we can never not have found data, so we don't check for this */
+        if (!watchdog_is_open)
+                kref_get(&data->kref);
+
+        mutex_unlock(&watchdog_data_mutex);
+
+        /* Check, if device is already open and possibly issue error */
+        if (watchdog_is_open)
+                return -EBUSY;
+
+        /* Enable Soft Watchdog */
+        watchdog_enable(data);
+
+        /* Store pointer to data into filp's private data */
+        filp->private_data = data;
+
+        return nonseekable_open(inode, filp);
+}
+
+static int watchdog_close(struct inode *inode, struct file *filp)
+{
+        struct w83793_data *data = filp->private_data;
 
+        if (data->watchdog_expect_close) {
+                watchdog_disable(data);
+                data->watchdog_expect_close = 0;
+        } else {
+                watchdog_trigger(data);
+                dev_crit(&data->client->dev,
+                        "unexpected close, not stopping watchdog!\n");
+        }
+
+        clear_bit(0, &data->watchdog_is_open);
+
+        /* Decrease data reference counter */
+        mutex_lock(&watchdog_data_mutex);
+        kref_put(&data->kref, w83793_release_resources);
+        mutex_unlock(&watchdog_data_mutex);
+
+        return 0;
+}
+
+static ssize_t watchdog_write(struct file *filp, const char __user *buf,
+        size_t count, loff_t *offset)
+{
+        size_t ret;
+        struct w83793_data *data = filp->private_data;
+
+        if (count) {
+                if (!nowayout) {
+                        size_t i;
+
+                        /* Clear it in case it was set with a previous write */
+                        data->watchdog_expect_close = 0;
+
+                        for (i = 0; i != count; i++) {
+                                char c;
+                                if (get_user(c, buf + i))
+                                        return -EFAULT;
+                                if (c == 'V')
+                                        data->watchdog_expect_close = 1;
+                        }
+                }
+                ret = watchdog_trigger(data);
+                if (ret < 0)
+                        return ret;
+        }
+        return count;
+}
+
+static int watchdog_ioctl(struct inode *inode, struct file *filp,
+                          unsigned int cmd, unsigned long arg)
+{
+        static struct watchdog_info ident = {
+                .options = WDIOF_KEEPALIVEPING |
+                           WDIOF_SETTIMEOUT |
+                           WDIOF_CARDRESET,
+                .identity = "w83793 watchdog"
+        };
+
+        int val, ret = 0;
+        struct w83793_data *data = filp->private_data;
+
+        switch (cmd) {
+        case WDIOC_GETSUPPORT:
+                if (!nowayout)
+                        ident.options |= WDIOF_MAGICCLOSE;
+                if (copy_to_user((void __user *)arg, &ident, sizeof(ident)))
+                        ret = -EFAULT;
+                break;
+
+        case WDIOC_GETSTATUS:
+                val = data->watchdog_caused_reboot ? WDIOF_CARDRESET : 0;
+                ret = put_user(val, (int __user *)arg);
+                break;
+
+        case WDIOC_GETBOOTSTATUS:
+                ret = put_user(0, (int __user *)arg);
+                break;
+
+        case WDIOC_KEEPALIVE:
+                ret = watchdog_trigger(data);
+                break;
+
+        case WDIOC_GETTIMEOUT:
+                val = watchdog_get_timeout(data);
+                ret = put_user(val, (int __user *)arg);
+                break;
+
+        case WDIOC_SETTIMEOUT:
+                if (get_user(val, (int __user *)arg)) {
+                        ret = -EFAULT;
+                        break;
+                }
+                ret = watchdog_set_timeout(data, val);
+                if (ret > 0)
+                        ret = put_user(ret, (int __user *)arg);
+                break;
+
+        case WDIOC_SETOPTIONS:
+                if (get_user(val, (int __user *)arg)) {
+                        ret = -EFAULT;
+                        break;
+                }
+
+                if (val & WDIOS_DISABLECARD)
+                        ret = watchdog_disable(data);
+                else if (val & WDIOS_ENABLECARD)
+                        ret = watchdog_enable(data);
+                else
+                        ret = -EINVAL;
+
+                break;
+        default:
+                ret = -ENOTTY;
+        }
+
+        return ret;
+}
+
+static const struct file_operations watchdog_fops = {
+        .owner = THIS_MODULE,
+        .llseek = no_llseek,
+        .open = watchdog_open,
+        .release = watchdog_close,
+        .write = watchdog_write,
+        .ioctl = watchdog_ioctl,
+};
+
+/*
+ *      Notifier for system down
+ */
+
+static int watchdog_notify_sys(struct notifier_block *this, unsigned long code,
+                               void *unused)
+{
+        struct w83793_data *data = NULL;
+
+        if (code == SYS_DOWN || code == SYS_HALT) {
+
+                /* Disable each registered watchdog */
+                mutex_lock(&watchdog_data_mutex);
+                list_for_each_entry(data, &watchdog_data_list, list) {
+                        if (data->watchdog_miscdev.minor)
+                                watchdog_disable(data);
+                }
+                mutex_unlock(&watchdog_data_mutex);
+        }
+
+        return NOTIFY_DONE;
 }
 
+/*
+ *      The WDT needs to learn about soft shutdowns in order to
+ *      turn the timebomb registers off.
+ */
+
+static struct notifier_block watchdog_notifier = {
+        .notifier_call = watchdog_notify_sys,
+};
+
+/*
+ * Init / remove routines
+ */
+
 static int w83793_remove(struct i2c_client *client)
 {
         struct w83793_data *data = i2c_get_clientdata(client);
         struct device *dev = &client->dev;
-        int i;
+        int i, tmp;
+
+        /* Unregister the watchdog (if registered) */
+        if (data->watchdog_miscdev.minor) {
+                misc_deregister(&data->watchdog_miscdev);
+
+                if (data->watchdog_is_open) {
+                        dev_warn(&client->dev,
+                                "i2c client detached with watchdog open! "
+                                "Stopping watchdog.\n");
+                        watchdog_disable(data);
+                }
+
+                mutex_lock(&watchdog_data_mutex);
+                list_del(&data->list);
+                mutex_unlock(&watchdog_data_mutex);
+
+                /* Tell the watchdog code the client is gone */
+                mutex_lock(&data->watchdog_lock);
+                data->client = NULL;
+                mutex_unlock(&data->watchdog_lock);
+        }
+
+        /* Reset Configuration Register to Disable Watch Dog Registers */
+        tmp = w83793_read_value(client, W83793_REG_CONFIG);
+        w83793_write_value(client, W83793_REG_CONFIG, tmp & ~0x04);
+
+        unregister_reboot_notifier(&watchdog_notifier);
 
         hwmon_device_unregister(data->hwmon_dev);
 
@@ -1099,7 +1494,10 @@ static int w83793_remove(struct i2c_client *client)
         if (data->lm75[1] != NULL)
                 i2c_unregister_device(data->lm75[1]);
 
-        kfree(data);
+        /* Decrease data reference counter */
+        mutex_lock(&watchdog_data_mutex);
+        kref_put(&data->kref, w83793_release_resources);
+        mutex_unlock(&watchdog_data_mutex);
 
         return 0;
 }
@@ -1203,6 +1601,7 @@ static int w83793_probe(struct i2c_client *client,
                         const struct i2c_device_id *id)
 {
         struct device *dev = &client->dev;
+        const int watchdog_minors[] = { WATCHDOG_MINOR, 212, 213, 214, 215 };
         struct w83793_data *data;
         int i, tmp, val, err;
         int files_fan = ARRAY_SIZE(w83793_left_fan) / 7;
@@ -1218,6 +1617,14 @@ static int w83793_probe(struct i2c_client *client,
         i2c_set_clientdata(client, data);
         data->bank = i2c_smbus_read_byte_data(client, W83793_REG_BANKSEL);
         mutex_init(&data->update_lock);
+        mutex_init(&data->watchdog_lock);
+        INIT_LIST_HEAD(&data->list);
+        kref_init(&data->kref);
+
+        /* Store client pointer in our data struct for watchdog usage
+           (where the client is found through a data ptr instead of the
+           otherway around) */
+        data->client = client;
 
         err = w83793_detect_subclients(client);
         if (err)
@@ -1380,8 +1787,77 @@ static int w83793_probe(struct i2c_client *client,
                 goto exit_remove;
         }
 
+        /* Watchdog initialization */
+
+        /* Register boot notifier */
+        err = register_reboot_notifier(&watchdog_notifier);
+        if (err != 0) {
+                dev_err(&client->dev,
+                        "cannot register reboot notifier (err=%d)\n", err);
+                goto exit_devunreg;
+        }
+
+        /* Enable Watchdog registers.
+           Set Configuration Register to Enable Watch Dog Registers
+           (Bit 2) = XXXX, X1XX. */
+        tmp = w83793_read_value(client, W83793_REG_CONFIG);
+        w83793_write_value(client, W83793_REG_CONFIG, tmp | 0x04);
+
+        /* Set the default watchdog timeout */
+        data->watchdog_timeout = timeout;
+
+        /* Check, if last reboot was caused by watchdog */
+        data->watchdog_caused_reboot =
+          w83793_read_value(data->client, W83793_REG_WDT_STATUS) & 0x01;
+
+        /* Disable Soft Watchdog during initialiation */
+        watchdog_disable(data);
+
+        /* We take the data_mutex lock early so that watchdog_open() cannot
+           run when misc_register() has completed, but we've not yet added
+           our data to the watchdog_data_list (and set the default timeout) */
+        mutex_lock(&watchdog_data_mutex);
+        for (i = 0; i < ARRAY_SIZE(watchdog_minors); i++) {
+                /* Register our watchdog part */
+                snprintf(data->watchdog_name, sizeof(data->watchdog_name),
+                        "watchdog%c", (i == 0) ? '\0' : ('0' + i));
+                data->watchdog_miscdev.name = data->watchdog_name;
+                data->watchdog_miscdev.fops = &watchdog_fops;
+                data->watchdog_miscdev.minor = watchdog_minors[i];
+
+                err = misc_register(&data->watchdog_miscdev);
+                if (err == -EBUSY)
+                        continue;
+                if (err) {
+                        data->watchdog_miscdev.minor = 0;
+                        dev_err(&client->dev,
+                                "Registering watchdog chardev: %d\n", err);
+                        break;
+                }
+
+                list_add(&data->list, &watchdog_data_list);
+
+                dev_info(&client->dev,
+                        "Registered watchdog chardev major 10, minor: %d\n",
+                        watchdog_minors[i]);
+                break;
+        }
+        if (i == ARRAY_SIZE(watchdog_minors)) {
+                data->watchdog_miscdev.minor = 0;
+                dev_warn(&client->dev, "Couldn't register watchdog chardev "
+                        "(due to no free minor)\n");
+        }
+
+        mutex_unlock(&watchdog_data_mutex);
+
         return 0;
 
+        /* Unregister hwmon device */
+
+exit_devunreg:
+
+        hwmon_device_unregister(data->hwmon_dev);
+
         /* Unregister sysfs hooks */
 
 exit_remove:
@@ -1628,7 +2104,7 @@ static void __exit sensors_w83793_exit(void)
         i2c_del_driver(&w83793_driver);
 }
 
-MODULE_AUTHOR("Yuan Mu");
+MODULE_AUTHOR("Yuan Mu, Sven Anders");
 MODULE_DESCRIPTION("w83793 driver");
 MODULE_LICENSE("GPL");