hwmon: (adm1031) Allow setting update rate

Based on earlier work by Ira W. Snyder.

The adm1031 chip is capable of using a runtime configurable sampling rate,
using the fan filter register. Add support for reading and setting the
update rate via sysfs.

Signed-off-by: Jean Delvare <khali@linux-fr.org>
Acked-by: Ira W. Snyder <iws@ovro.caltech.edu>

1 files changed, 66 insertions, 2 deletions

diff --git a/drivers/hwmon/adm1031.c b/drivers/hwmon/adm1031.c
index 1644b92e7cc4..15c1a9616af3 100644
--- a/drivers/hwmon/adm1031.c
+++ b/drivers/hwmon/adm1031.c
@@ -36,6 +36,7 @@
 #define ADM1031_REG_FAN_DIV(nr)         (0x20 + (nr))
 #define ADM1031_REG_PWM                 (0x22)
 #define ADM1031_REG_FAN_MIN(nr)         (0x10 + (nr))
+#define ADM1031_REG_FAN_FILTER          (0x23)
 
 #define ADM1031_REG_TEMP_OFFSET(nr)     (0x0d + (nr))
 #define ADM1031_REG_TEMP_MAX(nr)        (0x14 + 4 * (nr))
@@ -61,6 +62,9 @@
 #define ADM1031_CONF2_TACH2_ENABLE      0x08
 #define ADM1031_CONF2_TEMP_ENABLE(chan) (0x10 << (chan))
 
+#define ADM1031_UPDATE_RATE_MASK        0x1c
+#define ADM1031_UPDATE_RATE_SHIFT       2
+
 /* Addresses to scan */
 static const unsigned short normal_i2c[] = { 0x2c, 0x2d, 0x2e, I2C_CLIENT_END };
 
@@ -75,6 +79,7 @@ struct adm1031_data {
         int chip_type;
         char valid;             /* !=0 if following fields are valid */
         unsigned long last_updated;     /* In jiffies */
+        unsigned int update_rate;       /* In milliseconds */
         /* The chan_select_table contains the possible configurations for
          * auto fan control.
          */
@@ -738,6 +743,57 @@ static SENSOR_DEVICE_ATTR(temp3_crit_alarm, S_IRUGO, show_alarm, NULL, 12);
 static SENSOR_DEVICE_ATTR(temp3_fault, S_IRUGO, show_alarm, NULL, 13);
 static SENSOR_DEVICE_ATTR(temp1_crit_alarm, S_IRUGO, show_alarm, NULL, 14);
 
+/* Update Rate */
+static const unsigned int update_rates[] = {
+        16000, 8000, 4000, 2000, 1000, 500, 250, 125,
+};
+
+static ssize_t show_update_rate(struct device *dev,
+                                struct device_attribute *attr, char *buf)
+{
+        struct i2c_client *client = to_i2c_client(dev);
+        struct adm1031_data *data = i2c_get_clientdata(client);
+
+        return sprintf(buf, "%u\n", data->update_rate);
+}
+
+static ssize_t set_update_rate(struct device *dev,
+                               struct device_attribute *attr,
+                               const char *buf, size_t count)
+{
+        struct i2c_client *client = to_i2c_client(dev);
+        struct adm1031_data *data = i2c_get_clientdata(client);
+        unsigned long val;
+        int i, err;
+        u8 reg;
+
+        err = strict_strtoul(buf, 10, &val);
+        if (err)
+                return err;
+
+        /* find the nearest update rate from the table */
+        for (i = 0; i < ARRAY_SIZE(update_rates) - 1; i++) {
+                if (val >= update_rates[i])
+                        break;
+        }
+        /* if not found, we point to the last entry (lowest update rate) */
+
+        /* set the new update rate while preserving other settings */
+        reg = adm1031_read_value(client, ADM1031_REG_FAN_FILTER);
+        reg &= ~ADM1031_UPDATE_RATE_MASK;
+        reg |= i << ADM1031_UPDATE_RATE_SHIFT;
+        adm1031_write_value(client, ADM1031_REG_FAN_FILTER, reg);
+
+        mutex_lock(&data->update_lock);
+        data->update_rate = update_rates[i];
+        mutex_unlock(&data->update_lock);
+
+        return count;
+}
+
+static DEVICE_ATTR(update_rate, S_IRUGO | S_IWUSR, show_update_rate,
+                   set_update_rate);
+
 static struct attribute *adm1031_attributes[] = {
         &sensor_dev_attr_fan1_input.dev_attr.attr,
         &sensor_dev_attr_fan1_div.dev_attr.attr,
@@ -774,6 +830,7 @@ static struct attribute *adm1031_attributes[] = {
 
         &sensor_dev_attr_auto_fan1_min_pwm.dev_attr.attr,
 
+        &dev_attr_update_rate.attr,
         &dev_attr_alarms.attr,
 
         NULL
@@ -900,6 +957,7 @@ static void adm1031_init_client(struct i2c_client *client)
 {
         unsigned int read_val;
         unsigned int mask;
+        int i;
         struct adm1031_data *data = i2c_get_clientdata(client);
 
         mask = (ADM1031_CONF2_PWM1_ENABLE | ADM1031_CONF2_TACH1_ENABLE);
@@ -919,18 +977,24 @@ static void adm1031_init_client(struct i2c_client *client)
                                 ADM1031_CONF1_MONITOR_ENABLE);
         }
 
+        /* Read the chip's update rate */
+        mask = ADM1031_UPDATE_RATE_MASK;
+        read_val = adm1031_read_value(client, ADM1031_REG_FAN_FILTER);
+        i = (read_val & mask) >> ADM1031_UPDATE_RATE_SHIFT;
+        data->update_rate = update_rates[i];
 }
 
 static struct adm1031_data *adm1031_update_device(struct device *dev)
 {
         struct i2c_client *client = to_i2c_client(dev);
         struct adm1031_data *data = i2c_get_clientdata(client);
+        unsigned long next_update;
         int chan;
 
         mutex_lock(&data->update_lock);
 
-        if (time_after(jiffies, data->last_updated + HZ + HZ / 2)
-            || !data->valid) {
+        next_update = data->last_updated + msecs_to_jiffies(data->update_rate);
+        if (time_after(jiffies, next_update) || !data->valid) {
 
                 dev_dbg(&client->dev, "Starting adm1031 update\n");
                 for (chan = 0;