adt7470: make automatic fan control really work

It turns out that the adt7470's automatic fan control algorithm only works
when the temperature sensors get updated.  This in turn happens only when
someone tells the chip to read its temperature sensors.  Regrettably, this
means that we have to drive the chip periodically.

Signed-off-by: Darrick J. Wong <djwong@us.ibm.com>
Cc: Jean Delvare <khali@linux-fr.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 134 insertions, 22 deletions

diff --git a/drivers/hwmon/adt7470.c b/drivers/hwmon/adt7470.c
index ab8d5ebc9f75..633e1a1e9d79 100644
--- a/drivers/hwmon/adt7470.c
+++ b/drivers/hwmon/adt7470.c
@@ -28,6 +28,7 @@
 #include <linux/mutex.h>
 #include <linux/delay.h>
 #include <linux/log2.h>
+#include <linux/kthread.h>
 
 /* Addresses to scan */
 static const unsigned short normal_i2c[] = { 0x2C, 0x2E, 0x2F, I2C_CLIENT_END };
@@ -132,6 +133,9 @@ I2C_CLIENT_INSMOD_1(adt7470);
 /* Wait at least 200ms per sensor for 10 sensors */
 #define TEMP_COLLECTION_TIME    2000
 
+/* auto update thing won't fire more than every 2s */
+#define AUTO_UPDATE_INTERVAL    2000
+
 /* datasheet says to divide this number by the fan reading to get fan rpm */
 #define FAN_PERIOD_TO_RPM(x)    ((90000 * 60) / (x))
 #define FAN_RPM_TO_PERIOD       FAN_PERIOD_TO_RPM
@@ -148,6 +152,7 @@ struct adt7470_data {
         unsigned long           limits_last_updated;    /* In jiffies */
 
         int                     num_temp_sensors;       /* -1 = probe */
+        int                     temperatures_probed;
 
         s8                      temp[ADT7470_TEMP_COUNT];
         s8                      temp_min[ADT7470_TEMP_COUNT];
@@ -164,6 +169,10 @@ struct adt7470_data {
         u8                      pwm_min[ADT7470_PWM_COUNT];
         s8                      pwm_tmin[ADT7470_PWM_COUNT];
         u8                      pwm_auto_temp[ADT7470_PWM_COUNT];
+
+        struct task_struct      *auto_update;
+        struct completion       auto_update_stop;
+        unsigned int            auto_update_interval;
 };
 
 static int adt7470_probe(struct i2c_client *client,
@@ -221,19 +230,13 @@ static void adt7470_init_client(struct i2c_client *client)
         }
 }
 
-static struct adt7470_data *adt7470_update_device(struct device *dev)
+/* Probe for temperature sensors.  Assumes lock is held */
+static int adt7470_read_temperatures(struct i2c_client *client,
+                                     struct adt7470_data *data)
 {
-        struct i2c_client *client = to_i2c_client(dev);
-        struct adt7470_data *data = i2c_get_clientdata(client);
-        unsigned long local_jiffies = jiffies;
-        u8 cfg, pwm[4], pwm_cfg[2];
+        unsigned long res;
         int i;
-
-        mutex_lock(&data->lock);
-        if (time_before(local_jiffies, data->sensors_last_updated +
-                SENSOR_REFRESH_INTERVAL)
-                && data->sensors_valid)
-                goto no_sensor_update;
+        u8 cfg, pwm[4], pwm_cfg[2];
 
         /* save pwm[1-4] config register */
         pwm_cfg[0] = i2c_smbus_read_byte_data(client, ADT7470_REG_PWM_CFG(0));
@@ -259,9 +262,9 @@ static struct adt7470_data *adt7470_update_device(struct device *dev)
         i2c_smbus_write_byte_data(client, ADT7470_REG_CFG, cfg);
 
         /* Delay is 200ms * number of temp sensors. */
-        msleep((data->num_temp_sensors >= 0 ?
-                data->num_temp_sensors * 200 :
-                TEMP_COLLECTION_TIME));
+        res = msleep_interruptible((data->num_temp_sensors >= 0 ?
+                                    data->num_temp_sensors * 200 :
+                                    TEMP_COLLECTION_TIME));
 
         /* done reading temperature sensors */
         cfg = i2c_smbus_read_byte_data(client, ADT7470_REG_CFG);
@@ -272,15 +275,81 @@ static struct adt7470_data *adt7470_update_device(struct device *dev)
         i2c_smbus_write_byte_data(client, ADT7470_REG_PWM_CFG(0), pwm_cfg[0]);
         i2c_smbus_write_byte_data(client, ADT7470_REG_PWM_CFG(2), pwm_cfg[1]);
 
-        for (i = 0; i < ADT7470_TEMP_COUNT; i++)
+        if (res) {
+                printk(KERN_ERR "ha ha, interrupted");
+                return -EAGAIN;
+        }
+
+        /* Only count fans if we have to */
+        if (data->num_temp_sensors >= 0)
+                return 0;
+
+        for (i = 0; i < ADT7470_TEMP_COUNT; i++) {
                 data->temp[i] = i2c_smbus_read_byte_data(client,
                                                 ADT7470_TEMP_REG(i));
+                if (data->temp[i])
+                        data->num_temp_sensors = i + 1;
+        }
+        data->temperatures_probed = 1;
+        return 0;
+}
 
-        /* Figure out the number of temp sensors */
-        if (data->num_temp_sensors < 0)
+static int adt7470_update_thread(void *p)
+{
+        struct i2c_client *client = p;
+        struct adt7470_data *data = i2c_get_clientdata(client);
+
+        while (!kthread_should_stop()) {
+                mutex_lock(&data->lock);
+                adt7470_read_temperatures(client, data);
+                mutex_unlock(&data->lock);
+                if (kthread_should_stop())
+                        break;
+                msleep_interruptible(data->auto_update_interval);
+        }
+
+        complete_all(&data->auto_update_stop);
+        return 0;
+}
+
+static struct adt7470_data *adt7470_update_device(struct device *dev)
+{
+        struct i2c_client *client = to_i2c_client(dev);
+        struct adt7470_data *data = i2c_get_clientdata(client);
+        unsigned long local_jiffies = jiffies;
+        u8 cfg;
+        int i;
+        int need_sensors = 1;
+        int need_limits = 1;
+
+        /*
+         * Figure out if we need to update the shadow registers.
+         * Lockless means that we may occasionally report out of
+         * date data.
+         */
+        if (time_before(local_jiffies, data->sensors_last_updated +
+                        SENSOR_REFRESH_INTERVAL) &&
+            data->sensors_valid)
+                need_sensors = 0;
+
+        if (time_before(local_jiffies, data->limits_last_updated +
+                        LIMIT_REFRESH_INTERVAL) &&
+            data->limits_valid)
+                need_limits = 0;
+
+        if (!need_sensors && !need_limits)
+                return data;
+
+        mutex_lock(&data->lock);
+        if (!need_sensors)
+                goto no_sensor_update;
+
+        if (!data->temperatures_probed)
+                adt7470_read_temperatures(client, data);
+        else
                 for (i = 0; i < ADT7470_TEMP_COUNT; i++)
-                        if (data->temp[i])
-                                data->num_temp_sensors = i + 1;
+                        data->temp[i] = i2c_smbus_read_byte_data(client,
+                                                ADT7470_TEMP_REG(i));
 
         for (i = 0; i < ADT7470_FAN_COUNT; i++)
                 data->fan[i] = adt7470_read_word_data(client,
@@ -329,9 +398,7 @@ static struct adt7470_data *adt7470_update_device(struct device *dev)
         data->sensors_valid = 1;
 
 no_sensor_update:
-        if (time_before(local_jiffies, data->limits_last_updated +
-                LIMIT_REFRESH_INTERVAL)
-                && data->limits_valid)
+        if (!need_limits)
                 goto out;
 
         for (i = 0; i < ADT7470_TEMP_COUNT; i++) {
@@ -365,6 +432,35 @@ out:
         return data;
 }
 
+static ssize_t show_auto_update_interval(struct device *dev,
+                                         struct device_attribute *devattr,
+                                         char *buf)
+{
+        struct adt7470_data *data = adt7470_update_device(dev);
+        return sprintf(buf, "%d\n", data->auto_update_interval);
+}
+
+static ssize_t set_auto_update_interval(struct device *dev,
+                                        struct device_attribute *devattr,
+                                        const char *buf,
+                                        size_t count)
+{
+        struct i2c_client *client = to_i2c_client(dev);
+        struct adt7470_data *data = i2c_get_clientdata(client);
+        long temp;
+
+        if (strict_strtol(buf, 10, &temp))
+                return -EINVAL;
+
+        temp = SENSORS_LIMIT(temp, 0, 60000);
+
+        mutex_lock(&data->lock);
+        data->auto_update_interval = temp;
+        mutex_unlock(&data->lock);
+
+        return count;
+}
+
 static ssize_t show_num_temp_sensors(struct device *dev,
                                      struct device_attribute *devattr,
                                      char *buf)
@@ -389,6 +485,8 @@ static ssize_t set_num_temp_sensors(struct device *dev,
 
         mutex_lock(&data->lock);
         data->num_temp_sensors = temp;
+        if (temp < 0)
+                data->temperatures_probed = 0;
         mutex_unlock(&data->lock);
 
         return count;
@@ -862,6 +960,8 @@ static ssize_t show_alarm(struct device *dev,
 static DEVICE_ATTR(alarm_mask, S_IRUGO, show_alarm_mask, NULL);
 static DEVICE_ATTR(num_temp_sensors, S_IWUSR | S_IRUGO, show_num_temp_sensors,
                    set_num_temp_sensors);
+static DEVICE_ATTR(auto_update_interval, S_IWUSR | S_IRUGO,
+                   show_auto_update_interval, set_auto_update_interval);
 
 static SENSOR_DEVICE_ATTR(temp1_max, S_IWUSR | S_IRUGO, show_temp_max,
                     set_temp_max, 0);
@@ -1035,6 +1135,7 @@ static struct attribute *adt7470_attr[] =
 {
         &dev_attr_alarm_mask.attr,
         &dev_attr_num_temp_sensors.attr,
+        &dev_attr_auto_update_interval.attr,
         &sensor_dev_attr_temp1_max.dev_attr.attr,
         &sensor_dev_attr_temp2_max.dev_attr.attr,
         &sensor_dev_attr_temp3_max.dev_attr.attr,
@@ -1168,6 +1269,7 @@ static int adt7470_probe(struct i2c_client *client,
         }
 
         data->num_temp_sensors = -1;
+        data->auto_update_interval = AUTO_UPDATE_INTERVAL;
 
         i2c_set_clientdata(client, data);
         mutex_init(&data->lock);
@@ -1188,8 +1290,16 @@ static int adt7470_probe(struct i2c_client *client,
                 goto exit_remove;
         }
 
+        init_completion(&data->auto_update_stop);
+        data->auto_update = kthread_run(adt7470_update_thread, client,
+                                        dev_name(data->hwmon_dev));
+        if (IS_ERR(data->auto_update))
+                goto exit_unregister;
+
         return 0;
 
+exit_unregister:
+        hwmon_device_unregister(data->hwmon_dev);
 exit_remove:
         sysfs_remove_group(&client->dev.kobj, &data->attrs);
 exit_free:
@@ -1202,6 +1312,8 @@ static int adt7470_remove(struct i2c_client *client)
 {
         struct adt7470_data *data = i2c_get_clientdata(client);
 
+        kthread_stop(data->auto_update);
+        wait_for_completion(&data->auto_update_stop);
         hwmon_device_unregister(data->hwmon_dev);
         sysfs_remove_group(&client->dev.kobj, &data->attrs);
         kfree(data);