hwmon: (ds1621) Add ds1721 update interval sysfs attribute

The ds1721 device can be configured for 9..12 bit resolutions;
add a sysfs attribute for userspace to configure this attribute.
The definition, description, details, and usage are shown in the
documentation and were crafted from an LM73 driver patch done by
Chris Verges & Guenter Roeck).

Signed-off-by: Robert Coulson <rob.coulson@gmail.com>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>

1 files changed, 56 insertions, 0 deletions

diff --git a/drivers/hwmon/ds1621.c b/drivers/hwmon/ds1621.c
index 6942617666a4..b5d80fb851d0 100644
--- a/drivers/hwmon/ds1621.c
+++ b/drivers/hwmon/ds1621.c
@@ -274,7 +274,47 @@ static ssize_t show_alarm(struct device *dev, struct device_attribute *da,
         return sprintf(buf, "%d\n", !!(data->conf & attr->index));
 }
 
+static ssize_t show_convrate(struct device *dev, struct device_attribute *da,
+                          char *buf)
+{
+        struct i2c_client *client = to_i2c_client(dev);
+        struct ds1621_data *data = i2c_get_clientdata(client);
+        return scnprintf(buf, PAGE_SIZE, "%hu\n", data->update_interval);
+}
+
+static ssize_t set_convrate(struct device *dev, struct device_attribute *da,
+                            const char *buf, size_t count)
+{
+        struct i2c_client *client = to_i2c_client(dev);
+        struct ds1621_data *data = i2c_get_clientdata(client);
+        unsigned long convrate;
+        s32 err;
+        int resol = 0;
+
+        err = kstrtoul(buf, 10, &convrate);
+        if (err)
+                return err;
+
+        /* Convert rate into resolution bits */
+        while (resol < (ARRAY_SIZE(ds1721_convrates) - 1) &&
+               convrate > ds1721_convrates[resol])
+                resol++;
+
+        mutex_lock(&data->update_lock);
+        data->conf = i2c_smbus_read_byte_data(client, DS1621_REG_CONF);
+        data->conf &= ~DS1621_REG_CONFIG_RESOL;
+        data->conf |= (resol << DS1621_REG_CONFIG_RESOL_SHIFT);
+        i2c_smbus_write_byte_data(client, DS1621_REG_CONF, data->conf);
+        data->update_interval = ds1721_convrates[resol];
+        mutex_unlock(&data->update_lock);
+
+        return count;
+}
+
 static DEVICE_ATTR(alarms, S_IRUGO, show_alarms, NULL);
+static DEVICE_ATTR(update_interval, S_IWUSR | S_IRUGO, show_convrate,
+                   set_convrate);
+
 static SENSOR_DEVICE_ATTR(temp1_input, S_IRUGO, show_temp, NULL, 0);
 static SENSOR_DEVICE_ATTR(temp1_min, S_IWUSR | S_IRUGO, show_temp, set_temp, 1);
 static SENSOR_DEVICE_ATTR(temp1_max, S_IWUSR | S_IRUGO, show_temp, set_temp, 2);
@@ -290,11 +330,27 @@ static struct attribute *ds1621_attributes[] = {
         &sensor_dev_attr_temp1_min_alarm.dev_attr.attr,
         &sensor_dev_attr_temp1_max_alarm.dev_attr.attr,
         &dev_attr_alarms.attr,
+        &dev_attr_update_interval.attr,
         NULL
 };
 
+static umode_t ds1621_attribute_visible(struct kobject *kobj,
+                                        struct attribute *attr, int index)
+{
+        struct device *dev = container_of(kobj, struct device, kobj);
+        struct i2c_client *client = to_i2c_client(dev);
+        struct ds1621_data *data = i2c_get_clientdata(client);
+
+        if (attr == &dev_attr_update_interval.attr)
+                if (data->kind != ds1721)
+                        /* shhh, we're hiding update_interval */
+                        return 0;
+        return attr->mode;
+}
+
 static const struct attribute_group ds1621_group = {
         .attrs = ds1621_attributes,
+        .is_visible = ds1621_attribute_visible
 };