hwmon: (fschmd) Add watchdog support
Hans de Goede [Wed, 7 Jan 2009 15:37:33 +0000 (16:37 +0100)]
This patch adds support for the watchdog part found in _all_ supported FSC
sensor chips.

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

drivers/hwmon/Kconfig
drivers/hwmon/fschmd.c

index aba01b4..9197514 100644 (file)
@@ -329,10 +329,11 @@ config SENSORS_FSCHMD
        depends on X86 && I2C && EXPERIMENTAL
        help
          If you say yes here you get support for various Fujitsu Siemens
-         Computers sensor chips.
+         Computers sensor chips, including support for the integrated
+         watchdog.
 
          This is a new merged driver for FSC sensor chips which is intended
-         as a replacment for the fscpos, fscscy and fscher drivers and adds
+         as a replacement for the fscpos, fscscy and fscher drivers and adds
          support for several other FCS sensor chips.
 
          This driver can also be built as a module.  If so, the module
index c188b71..8bb1a44 100644 (file)
 #include <linux/mutex.h>
 #include <linux/sysfs.h>
 #include <linux/dmi.h>
+#include <linux/fs.h>
+#include <linux/watchdog.h>
+#include <linux/miscdevice.h>
+#include <linux/uaccess.h>
+#include <linux/kref.h>
 
 /* Addresses to scan */
 static const unsigned short normal_i2c[] = { 0x73, I2C_CLIENT_END };
 
 /* Insmod parameters */
+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) ")");
 I2C_CLIENT_INSMOD_5(fscpos, fscher, fscscy, fschrc, fschmd);
 
 /*
@@ -65,11 +74,18 @@ I2C_CLIENT_INSMOD_5(fscpos, fscher, fscscy, fschrc, fschmd);
 
 #define FSCHMD_CONTROL_ALERT_LED       0x01
 
-/* watchdog (support to be implemented) */
+/* watchdog */
 #define FSCHMD_REG_WDOG_PRESET         0x28
 #define FSCHMD_REG_WDOG_STATE          0x23
 #define FSCHMD_REG_WDOG_CONTROL                0x21
 
+#define FSCHMD_WDOG_CONTROL_TRIGGER    0x10
+#define FSCHMD_WDOG_CONTROL_STARTED    0x10 /* the same as trigger */
+#define FSCHMD_WDOG_CONTROL_STOP       0x20
+#define FSCHMD_WDOG_CONTROL_RESOLUTION 0x40
+
+#define FSCHMD_WDOG_STATE_CARDRESET    0x02
+
 /* voltages, weird order is to keep the same order as the old drivers */
 static const u8 FSCHMD_REG_VOLT[3] = { 0x45, 0x42, 0x48 };
 
@@ -206,14 +222,26 @@ static struct i2c_driver fschmd_driver = {
  */
 
 struct fschmd_data {
+       struct i2c_client *client;
        struct device *hwmon_dev;
        struct mutex update_lock;
+       struct mutex watchdog_lock;
+       struct list_head list; /* member of the watchdog_data_list */
+       struct kref kref;
+       struct miscdevice watchdog_miscdev;
        int kind;
+       unsigned long watchdog_is_open;
+       char watchdog_expect_close;
+       char watchdog_name[10]; /* must be unique to avoid sysfs conflict */
        char valid; /* zero until following fields are valid */
        unsigned long last_updated; /* in jiffies */
 
        /* register values */
+       u8 revision;            /* chip revision */
        u8 global_control;      /* global control register */
+       u8 watchdog_control;    /* watchdog control register */
+       u8 watchdog_state;      /* watchdog status register */
+       u8 watchdog_preset;     /* watchdog counter preset on trigger val */
        u8 volt[3];             /* 12, 5, battery voltage */
        u8 temp_act[5];         /* temperature */
        u8 temp_status[5];      /* status of sensor */
@@ -225,11 +253,28 @@ struct fschmd_data {
 };
 
 /* Global variables to hold information read from special DMI tables, which are
-   available on FSC machines with an fscher or later chip. */
+   available on FSC machines with an fscher or later chip. There is no need to
+   protect these with a lock as they are only modified from our attach function
+   which always gets called with the i2c-core lock held and never accessed
+   before the attach function is done with them. */
 static int dmi_mult[3] = { 490, 200, 100 };
 static int dmi_offset[3] = { 0, 0, 0 };
 static int dmi_vref = -1;
 
+/* Somewhat ugly :( global data pointer list with all fschmd devices, so that
+   we can find our device data as when using misc_register there is no other
+   method to get to ones device data from the open fop. */
+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 fschmd_release_resources(struct kref *ref)
+{
+       struct fschmd_data *data = container_of(ref, struct fschmd_data, kref);
+       kfree(data);
+}
 
 /*
  * Sysfs attr show / store functions
@@ -548,7 +593,265 @@ static struct sensor_device_attribute fschmd_fan_attr[] = {
 
 
 /*
- * Real code
+ * Watchdog routines
+ */
+
+static int watchdog_set_timeout(struct fschmd_data *data, int timeout)
+{
+       int ret, resolution;
+       int kind = data->kind + 1; /* 0-x array index -> 1-x module param */
+
+       /* 2 second or 60 second resolution? */
+       if (timeout <= 510 || kind == fscpos || kind == fscscy)
+               resolution = 2;
+       else
+               resolution = 60;
+
+       if (timeout < resolution || timeout > (resolution * 255))
+               return -EINVAL;
+
+       mutex_lock(&data->watchdog_lock);
+       if (!data->client) {
+               ret = -ENODEV;
+               goto leave;
+       }
+
+       if (resolution == 2)
+               data->watchdog_control &= ~FSCHMD_WDOG_CONTROL_RESOLUTION;
+       else
+               data->watchdog_control |= FSCHMD_WDOG_CONTROL_RESOLUTION;
+
+       data->watchdog_preset = DIV_ROUND_UP(timeout, resolution);
+
+       /* Write new timeout value */
+       i2c_smbus_write_byte_data(data->client, FSCHMD_REG_WDOG_PRESET,
+               data->watchdog_preset);
+       /* Write new control register, do not trigger! */
+       i2c_smbus_write_byte_data(data->client, FSCHMD_REG_WDOG_CONTROL,
+               data->watchdog_control & ~FSCHMD_WDOG_CONTROL_TRIGGER);
+
+       ret = data->watchdog_preset * resolution;
+
+leave:
+       mutex_unlock(&data->watchdog_lock);
+       return ret;
+}
+
+static int watchdog_get_timeout(struct fschmd_data *data)
+{
+       int timeout;
+
+       mutex_lock(&data->watchdog_lock);
+       if (data->watchdog_control & FSCHMD_WDOG_CONTROL_RESOLUTION)
+               timeout = data->watchdog_preset * 60;
+       else
+               timeout = data->watchdog_preset * 2;
+       mutex_unlock(&data->watchdog_lock);
+
+       return timeout;
+}
+
+static int watchdog_trigger(struct fschmd_data *data)
+{
+       int ret = 0;
+
+       mutex_lock(&data->watchdog_lock);
+       if (!data->client) {
+               ret = -ENODEV;
+               goto leave;
+       }
+
+       data->watchdog_control |= FSCHMD_WDOG_CONTROL_TRIGGER;
+       i2c_smbus_write_byte_data(data->client, FSCHMD_REG_WDOG_CONTROL,
+                                       data->watchdog_control);
+leave:
+       mutex_unlock(&data->watchdog_lock);
+       return ret;
+}
+
+static int watchdog_stop(struct fschmd_data *data)
+{
+       int ret = 0;
+
+       mutex_lock(&data->watchdog_lock);
+       if (!data->client) {
+               ret = -ENODEV;
+               goto leave;
+       }
+
+       data->watchdog_control &= ~FSCHMD_WDOG_CONTROL_STARTED;
+       /* Don't store the stop flag in our watchdog control register copy, as
+          its a write only bit (read always returns 0) */
+       i2c_smbus_write_byte_data(data->client, FSCHMD_REG_WDOG_CONTROL,
+               data->watchdog_control | FSCHMD_WDOG_CONTROL_STOP);
+leave:
+       mutex_unlock(&data->watchdog_lock);
+       return ret;
+}
+
+static int watchdog_open(struct inode *inode, struct file *filp)
+{
+       struct fschmd_data *pos, *data = NULL;
+
+       /* We get called from drivers/char/misc.c with misc_mtx hold, and we
+          call misc_register() from fschmd_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;
+               }
+       }
+       /* Note we can never not have found data, so we don't check for this */
+       kref_get(&data->kref);
+       mutex_unlock(&watchdog_data_mutex);
+
+       if (test_and_set_bit(0, &data->watchdog_is_open))
+               return -EBUSY;
+
+       /* Start the watchdog */
+       watchdog_trigger(data);
+       filp->private_data = data;
+
+       return nonseekable_open(inode, filp);
+}
+
+static int watchdog_release(struct inode *inode, struct file *filp)
+{
+       struct fschmd_data *data = filp->private_data;
+
+       if (data->watchdog_expect_close) {
+               watchdog_stop(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);
+
+       mutex_lock(&watchdog_data_mutex);
+       kref_put(&data->kref, fschmd_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 fschmd_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 = "FSC watchdog"
+       };
+       int i, ret = 0;
+       struct fschmd_data *data = filp->private_data;
+
+       switch (cmd) {
+       case WDIOC_GETSUPPORT:
+               ident.firmware_version = data->revision;
+               if (!nowayout)
+                       ident.options |= WDIOF_MAGICCLOSE;
+               if (copy_to_user((void __user *)arg, &ident, sizeof(ident)))
+                       ret = -EFAULT;
+               break;
+
+       case WDIOC_GETSTATUS:
+               ret = put_user(0, (int __user *)arg);
+               break;
+
+       case WDIOC_GETBOOTSTATUS:
+               if (data->watchdog_state & FSCHMD_WDOG_STATE_CARDRESET)
+                       ret = put_user(WDIOF_CARDRESET, (int __user *)arg);
+               else
+                       ret = put_user(0, (int __user *)arg);
+               break;
+
+       case WDIOC_KEEPALIVE:
+               ret = watchdog_trigger(data);
+               break;
+
+       case WDIOC_GETTIMEOUT:
+               i = watchdog_get_timeout(data);
+               ret = put_user(i, (int __user *)arg);
+               break;
+
+       case WDIOC_SETTIMEOUT:
+               if (get_user(i, (int __user *)arg)) {
+                       ret = -EFAULT;
+                       break;
+               }
+               ret = watchdog_set_timeout(data, i);
+               if (ret > 0)
+                       ret = put_user(ret, (int __user *)arg);
+               break;
+
+       case WDIOC_SETOPTIONS:
+               if (get_user(i, (int __user *)arg)) {
+                       ret = -EFAULT;
+                       break;
+               }
+
+               if (i & WDIOS_DISABLECARD)
+                       ret = watchdog_stop(data);
+               else if (i & WDIOS_ENABLECARD)
+                       ret = watchdog_trigger(data);
+               else
+                       ret = -EINVAL;
+
+               break;
+       default:
+               ret = -ENOTTY;
+       }
+
+       return ret;
+}
+
+static struct file_operations watchdog_fops = {
+       .owner = THIS_MODULE,
+       .llseek = no_llseek,
+       .open = watchdog_open,
+       .release = watchdog_release,
+       .write = watchdog_write,
+       .ioctl = watchdog_ioctl,
+};
+
+
+/*
+ * Detect, register, unregister and update device functions
  */
 
 /* DMI decode routine to read voltage scaling factors from special DMI tables,
@@ -658,9 +961,9 @@ static int fschmd_probe(struct i2c_client *client,
                        const struct i2c_device_id *id)
 {
        struct fschmd_data *data;
-       u8 revision;
        const char * const names[5] = { "Poseidon", "Hermes", "Scylla",
                                        "Heracles", "Heimdall" };
+       const int watchdog_minors[] = { WATCHDOG_MINOR, 212, 213, 214, 215 };
        int i, err;
        enum chips kind = id->driver_data;
 
@@ -670,6 +973,13 @@ static int fschmd_probe(struct i2c_client *client,
 
        i2c_set_clientdata(client, data);
        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;
 
        if (kind == fscpos) {
                /* The Poseidon has hardwired temp limits, fill these
@@ -690,6 +1000,17 @@ static int fschmd_probe(struct i2c_client *client,
                }
        }
 
+       /* Read in some never changing registers */
+       data->revision = i2c_smbus_read_byte_data(client, FSCHMD_REG_REVISION);
+       data->global_control = i2c_smbus_read_byte_data(client,
+                                       FSCHMD_REG_CONTROL);
+       data->watchdog_control = i2c_smbus_read_byte_data(client,
+                                       FSCHMD_REG_WDOG_CONTROL);
+       data->watchdog_state = i2c_smbus_read_byte_data(client,
+                                       FSCHMD_REG_WDOG_STATE);
+       data->watchdog_preset = i2c_smbus_read_byte_data(client,
+                                       FSCHMD_REG_WDOG_PRESET);
+
        /* i2c kind goes from 1-5, we want from 0-4 to address arrays */
        data->kind = kind - 1;
 
@@ -732,9 +1053,43 @@ static int fschmd_probe(struct i2c_client *client,
                goto exit_detach;
        }
 
-       revision = i2c_smbus_read_byte_data(client, FSCHMD_REG_REVISION);
+       /* 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);
+               watchdog_set_timeout(data, 60);
+               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);
+
        dev_info(&client->dev, "Detected FSC %s chip, revision: %d\n",
-               names[data->kind], (int) revision);
+               names[data->kind], (int) data->revision);
 
        return 0;
 
@@ -748,6 +1103,24 @@ static int fschmd_remove(struct i2c_client *client)
        struct fschmd_data *data = i2c_get_clientdata(client);
        int i;
 
+       /* 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_stop(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);
+       }
+
        /* Check if registered in case we're called from fschmd_detect
           to cleanup after an error */
        if (data->hwmon_dev)
@@ -762,7 +1135,10 @@ static int fschmd_remove(struct i2c_client *client)
                device_remove_file(&client->dev,
                                        &fschmd_fan_attr[i].dev_attr);
 
-       kfree(data);
+       mutex_lock(&watchdog_data_mutex);
+       kref_put(&data->kref, fschmd_release_resources);
+       mutex_unlock(&watchdog_data_mutex);
+
        return 0;
 }
 
@@ -824,17 +1200,6 @@ static struct fschmd_data *fschmd_update_device(struct device *dev)
                        data->volt[i] = i2c_smbus_read_byte_data(client,
                                                FSCHMD_REG_VOLT[i]);
 
-               data->global_control = i2c_smbus_read_byte_data(client,
-                                               FSCHMD_REG_CONTROL);
-
-               /* To be implemented in the future
-               data->watchdog[0] = i2c_smbus_read_byte_data(client,
-                                               FSCHMD_REG_WDOG_PRESET);
-               data->watchdog[1] = i2c_smbus_read_byte_data(client,
-                                               FSCHMD_REG_WDOG_STATE);
-               data->watchdog[2] = i2c_smbus_read_byte_data(client,
-                                               FSCHMD_REG_WDOG_CONTROL); */
-
                data->last_updated = jiffies;
                data->valid = 1;
        }