hwmon: (tmp401) Add support for update_interval attribute

Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Acked-by: Jean Delvare <khali@linux-fr.org>

diff --git a/drivers/hwmon/tmp401.c b/drivers/hwmon/tmp401.c
index 0611462..fa6af51 100644 (file)
--- a/drivers/hwmon/tmp401.c
+++ b/drivers/hwmon/tmp401.c
@@ -127,6 +127,8 @@ struct tmp401_data {
        unsigned long last_updated; /* in jiffies */
        enum chips kind;
 
+       unsigned int update_interval;   /* in milliseconds */
+
        /* register values */
        u8 status;
        u8 config;
@@ -194,10 +196,13 @@ static struct tmp401_data *tmp401_update_device(struct device *dev)
        struct tmp401_data *data = i2c_get_clientdata(client);
        struct tmp401_data *ret = data;
        int val;
+       unsigned long next_update;
 
        mutex_lock(&data->update_lock);
 
-       if (time_after(jiffies, data->last_updated + HZ) || !data->valid) {
+       next_update = data->last_updated +
+                     msecs_to_jiffies(data->update_interval) + 1;
+       if (time_after(jiffies, next_update) || !data->valid) {
                val = i2c_smbus_read_byte_data(client, TMP401_STATUS);
                if (val < 0) {
                        ret = ERR_PTR(val);
@@ -372,6 +377,46 @@ static ssize_t reset_temp_history(struct device *dev,
        return count;
 }
 
+static ssize_t show_update_interval(struct device *dev,
+                                   struct device_attribute *attr, char *buf)
+{
+       struct i2c_client *client = to_i2c_client(dev);
+       struct tmp401_data *data = i2c_get_clientdata(client);
+
+       return sprintf(buf, "%u\n", data->update_interval);
+}
+
+static ssize_t set_update_interval(struct device *dev,
+                                  struct device_attribute *attr,
+                                  const char *buf, size_t count)
+{
+       struct i2c_client *client = to_i2c_client(dev);
+       struct tmp401_data *data = i2c_get_clientdata(client);
+       unsigned long val;
+       int err, rate;
+
+       err = kstrtoul(buf, 10, &val);
+       if (err)
+               return err;
+
+       /*
+        * For valid rates, interval can be calculated as
+        *      interval = (1 << (7 - rate)) * 125;
+        * Rounded rate is therefore
+        *      rate = 7 - __fls(interval * 4 / (125 * 3));
+        * Use clamp_val() to avoid overflows, and to ensure valid input
+        * for __fls.
+        */
+       val = clamp_val(val, 125, 16000);
+       rate = 7 - __fls(val * 4 / (125 * 3));
+       mutex_lock(&data->update_lock);
+       i2c_smbus_write_byte_data(client, TMP401_CONVERSION_RATE_WRITE, rate);
+       data->update_interval = (1 << (7 - rate)) * 125;
+       mutex_unlock(&data->update_lock);
+
+       return count;
+}
+
 static SENSOR_DEVICE_ATTR_2(temp1_input, S_IRUGO, show_temp, NULL, 0, 0);
 static SENSOR_DEVICE_ATTR_2(temp1_min, S_IWUSR | S_IRUGO, show_temp,
                            store_temp, 1, 0);
@@ -405,6 +450,9 @@ static SENSOR_DEVICE_ATTR(temp2_max_alarm, S_IRUGO, show_status, NULL,
 static SENSOR_DEVICE_ATTR(temp2_crit_alarm, S_IRUGO, show_status, NULL,
                          TMP401_STATUS_REMOTE_CRIT);
 
+static DEVICE_ATTR(update_interval, S_IRUGO | S_IWUSR, show_update_interval,
+                  set_update_interval);
+
 static struct attribute *tmp401_attributes[] = {
        &sensor_dev_attr_temp1_input.dev_attr.attr,
        &sensor_dev_attr_temp1_min.dev_attr.attr,
@@ -425,6 +473,8 @@ static struct attribute *tmp401_attributes[] = {
        &sensor_dev_attr_temp2_min_alarm.dev_attr.attr,
        &sensor_dev_attr_temp2_crit_alarm.dev_attr.attr,
 
+       &dev_attr_update_interval.attr,
+
        NULL
 };
 
@@ -466,9 +516,11 @@ static const struct attribute_group tmp411_group = {
 static void tmp401_init_client(struct i2c_client *client)
 {
        int config, config_orig;
+       struct tmp401_data *data = i2c_get_clientdata(client);
 
        /* Set the conversion rate to 2 Hz */
        i2c_smbus_write_byte_data(client, TMP401_CONVERSION_RATE_WRITE, 5);
+       data->update_interval = 500;
 
        /* Start conversions (disable shutdown if necessary) */
        config = i2c_smbus_read_byte_data(client, TMP401_CONFIG_READ);