hwmon: (lm75) Prepare to support per-chip resolution and sample time

Prepare the lm75 driver to support per-chip resolution and sample
time. For now we only make the code generic enough to support it, but
we still use the same, unchanged resolution (9-bit) and sample time
(1.5 s) for all chips.

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

1 files changed, 26 insertions, 5 deletions

diff --git a/drivers/hwmon/lm75.c b/drivers/hwmon/lm75.c
index 4670fbef6a9c..559e675db3c8 100644
--- a/drivers/hwmon/lm75.c
+++ b/drivers/hwmon/lm75.c
@@ -71,9 +71,12 @@ struct lm75_data {
         struct device           *hwmon_dev;
         struct mutex            update_lock;
         u8                      orig_conf;
+        u8                      resolution;     /* In bits, between 9 and 12 */
+        u8                      resolution_limits;
         char                    valid;          /* !=0 if registers are valid */
         unsigned long           last_updated;   /* In jiffies */
-        u16                     temp[3];        /* Register values,
+        unsigned long           sample_time;    /* In jiffies */
+        s16                     temp[3];        /* Register values,
                                                    0 = input
                                                    1 = max
                                                    2 = hyst */
@@ -93,12 +96,15 @@ static ssize_t show_temp(struct device *dev, struct device_attribute *da,
 {
         struct sensor_device_attribute *attr = to_sensor_dev_attr(da);
         struct lm75_data *data = lm75_update_device(dev);
+        long temp;
 
         if (IS_ERR(data))
                 return PTR_ERR(data);
 
-        return sprintf(buf, "%d\n",
-                       LM75_TEMP_FROM_REG(data->temp[attr->index]));
+        temp = ((data->temp[attr->index] >> (16 - data->resolution)) * 1000)
+               >> (data->resolution - 8);
+
+        return sprintf(buf, "%ld\n", temp);
 }
 
 static ssize_t set_temp(struct device *dev, struct device_attribute *da,
@@ -110,13 +116,25 @@ static ssize_t set_temp(struct device *dev, struct device_attribute *da,
         int nr = attr->index;
         long temp;
         int error;
+        u8 resolution;
 
         error = kstrtol(buf, 10, &temp);
         if (error)
                 return error;
 
+        /*
+         * Resolution of limit registers is assumed to be the same as the
+         * temperature input register resolution unless given explicitly.
+         */
+        if (attr->index && data->resolution_limits)
+                resolution = data->resolution_limits;
+        else
+                resolution = data->resolution;
+
         mutex_lock(&data->update_lock);
-        data->temp[nr] = LM75_TEMP_TO_REG(temp);
+        temp = clamp_val(temp, LM75_TEMP_MIN, LM75_TEMP_MAX);
+        data->temp[nr] = DIV_ROUND_CLOSEST(temp  << (resolution - 8),
+                                           1000) << (16 - resolution);
         lm75_write_value(client, LM75_REG_TEMP[nr], data->temp[nr]);
         mutex_unlock(&data->update_lock);
         return count;
@@ -190,6 +208,9 @@ lm75_probe(struct i2c_client *client, const struct i2c_device_id *id)
                 break;
         }
 
+        data->resolution = 9;
+        data->sample_time = HZ + HZ / 2;
+
         /* configure as specified */
         status = lm75_read_value(client, LM75_REG_CONF);
         if (status < 0) {
@@ -427,7 +448,7 @@ static struct lm75_data *lm75_update_device(struct device *dev)
 
         mutex_lock(&data->update_lock);
 
-        if (time_after(jiffies, data->last_updated + HZ + HZ / 2)
+        if (time_after(jiffies, data->last_updated + data->sample_time)
             || !data->valid) {
                 int i;
                 dev_dbg(&client->dev, "Starting lm75 update\n");