hwmon: (lm90) Add support for update_interval sysfs attribute

Signed-off-by: Guenter Roeck <guenter.roeck@ericsson.com>
Signed-off-by: Jean Delvare <khali@linux-fr.org>

drivers/hwmon/lm90.c

@@ -151,6 +151,9 @@ enum chips { lm90, adm1032, lm99, lm86, max6657, max6659, adt7461, max6680,
 #define MAX6659_REG_R_LOCAL_EMERG	0x17
 #define MAX6659_REG_W_LOCAL_EMERG	0x17
 
+#define LM90_DEF_CONVRATE_RVAL	6	/* Def conversion rate register value */
+#define LM90_MAX_CONVRATE_MS	16000	/* Maximum conversion rate in ms */
+
 /*
  * Device flags
  */
@@ -197,6 +200,7 @@ struct lm90_params {
 	u32 flags;		/* Capabilities */
 	u16 alert_alarms;	/* Which alarm bits trigger ALERT# */
 				/* Upper 8 bits for max6695/96 */
+	u8 max_convrate;	/* Maximum conversion rate register value */
 };
 
 static const struct lm90_params lm90_params[] = {
@@ -204,48 +208,59 @@ static const struct lm90_params lm90_params[] = {
 		.flags = LM90_HAVE_OFFSET | LM90_HAVE_REM_LIMIT_EXT
 		  | LM90_HAVE_BROKEN_ALERT,
 		.alert_alarms = 0x7c,
+		.max_convrate = 10,
 	},
 	[adt7461] = {
 		.flags = LM90_HAVE_OFFSET | LM90_HAVE_REM_LIMIT_EXT
 		  | LM90_HAVE_BROKEN_ALERT,
 		.alert_alarms = 0x7c,
+		.max_convrate = 10,
 	},
 	[lm86] = {
 		.flags = LM90_HAVE_OFFSET | LM90_HAVE_REM_LIMIT_EXT,
 		.alert_alarms = 0x7b,
+		.max_convrate = 9,
 	},
 	[lm90] = {
 		.flags = LM90_HAVE_OFFSET | LM90_HAVE_REM_LIMIT_EXT,
 		.alert_alarms = 0x7b,
+		.max_convrate = 9,
 	},
 	[lm99] = {
 		.flags = LM90_HAVE_OFFSET | LM90_HAVE_REM_LIMIT_EXT,
 		.alert_alarms = 0x7b,
+		.max_convrate = 9,
 	},
 	[max6646] = {
 		.flags = LM90_HAVE_LOCAL_EXT,
 		.alert_alarms = 0x7c,
+		.max_convrate = 6,
 	},
 	[max6657] = {
 		.flags = LM90_HAVE_LOCAL_EXT,
 		.alert_alarms = 0x7c,
+		.max_convrate = 8,
 	},
 	[max6659] = {
 		.flags = LM90_HAVE_LOCAL_EXT | LM90_HAVE_EMERGENCY,
 		.alert_alarms = 0x7c,
+		.max_convrate = 8,
 	},
 	[max6680] = {
 		.flags = LM90_HAVE_OFFSET,
 		.alert_alarms = 0x7c,
+		.max_convrate = 7,
 	},
 	[max6696] = {
 		.flags = LM90_HAVE_LOCAL_EXT | LM90_HAVE_EMERGENCY
 		  | LM90_HAVE_EMERGENCY_ALARM | LM90_HAVE_TEMP3,
 		.alert_alarms = 0x187c,
+		.max_convrate = 6,
 	},
 	[w83l771] = {
 		.flags = LM90_HAVE_OFFSET | LM90_HAVE_REM_LIMIT_EXT,
 		.alert_alarms = 0x7c,
+		.max_convrate = 8,
 	},
 };
 
@@ -261,9 +276,13 @@ struct lm90_data {
 	int kind;
 	u32 flags;
 
+	int update_interval;	/* in milliseconds */
+
 	u8 config_orig;		/* Original configuration register value */
+	u8 convrate_orig;	/* Original conversion rate register value */
 	u16 alert_alarms;	/* Which alarm bits trigger ALERT# */
 				/* Upper 8 bits for max6695/96 */
+	u8 max_convrate;	/* Maximum conversion rate */
 
 	/* registers values */
 	s8 temp8[8];	/* 0: local low limit
@@ -385,15 +404,41 @@ static inline void lm90_select_remote_channel(struct i2c_client *client,
 	}
 }
 
+/*
+ * Set conversion rate.
+ * client->update_lock must be held when calling this function (unless we are
+ * in detection or initialization steps).
+ */
+static void lm90_set_convrate(struct i2c_client *client, struct lm90_data *data,
+			      unsigned int interval)
+{
+	int i;
+	unsigned int update_interval;
+
+	/* Shift calculations to avoid rounding errors */
+	interval <<= 6;
+
+	/* find the nearest update rate */
+	for (i = 0, update_interval = LM90_MAX_CONVRATE_MS << 6;
+	     i < data->max_convrate; i++, update_interval >>= 1)
+		if (interval >= update_interval * 3 / 4)
+			break;
+
+	i2c_smbus_write_byte_data(client, LM90_REG_W_CONVRATE, i);
+	data->update_interval = DIV_ROUND_CLOSEST(update_interval, 64);
+}
+
 static struct lm90_data *lm90_update_device(struct device *dev)
 {
 	struct i2c_client *client = to_i2c_client(dev);
 	struct lm90_data *data = i2c_get_clientdata(client);
+	unsigned long next_update;
 
 	mutex_lock(&data->update_lock);
 
-	if (time_after(jiffies, data->last_updated + HZ / 2 + HZ / 10)
-	 || !data->valid) {
+	next_update = data->last_updated
+	  + msecs_to_jiffies(data->update_interval) + 1;
+	if (time_after(jiffies, next_update) || !data->valid) {
 		u8 h, l;
 		u8 alarms;
 
@@ -828,6 +873,34 @@ static ssize_t show_alarm(struct device *dev, struct device_attribute
 	return sprintf(buf, "%d\n", (data->alarms >> bitnr) & 1);
 }
 
+static ssize_t show_update_interval(struct device *dev,
+				    struct device_attribute *attr, char *buf)
+{
+	struct lm90_data *data = dev_get_drvdata(dev);
+
+	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 lm90_data *data = i2c_get_clientdata(client);
+	unsigned long val;
+	int err;
+
+	err = strict_strtoul(buf, 10, &val);
+	if (err)
+		return err;
+
+	mutex_lock(&data->update_lock);
+	lm90_set_convrate(client, data, val);
+	mutex_unlock(&data->update_lock);
+
+	return count;
+}
+
 static SENSOR_DEVICE_ATTR_2(temp1_input, S_IRUGO, show_temp11, NULL, 0, 4);
 static SENSOR_DEVICE_ATTR_2(temp2_input, S_IRUGO, show_temp11, NULL, 0, 0);
 static SENSOR_DEVICE_ATTR(temp1_min, S_IWUSR | S_IRUGO, show_temp8,
@@ -859,6 +932,9 @@ static SENSOR_DEVICE_ATTR(temp1_max_alarm, S_IRUGO, show_alarm, NULL, 6);
 /* Raw alarm file for compatibility */
 static DEVICE_ATTR(alarms, S_IRUGO, show_alarms, NULL);
 
+static DEVICE_ATTR(update_interval, S_IRUGO | S_IWUSR, show_update_interval,
+		   set_update_interval);
+
 static struct attribute *lm90_attributes[] = {
 	&sensor_dev_attr_temp1_input.dev_attr.attr,
 	&sensor_dev_attr_temp2_input.dev_attr.attr,
@@ -879,6 +955,7 @@ static struct attribute *lm90_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
 };
 
@@ -1198,14 +1275,19 @@ static void lm90_remove_files(struct i2c_client *client, struct lm90_data *data)
 
 static void lm90_init_client(struct i2c_client *client)
 {
-	u8 config;
+	u8 config, convrate;
 	struct lm90_data *data = i2c_get_clientdata(client);
 
+	if (lm90_read_reg(client, LM90_REG_R_CONVRATE, &convrate) < 0) {
+		dev_warn(&client->dev, "Failed to read convrate register!\n");
+		convrate = LM90_DEF_CONVRATE_RVAL;
+	}
+	data->convrate_orig = convrate;
+
 	/*
 	 * Start the conversions.
 	 */
-	i2c_smbus_write_byte_data(client, LM90_REG_W_CONVRATE,
-				  5); /* 2 Hz */
+	lm90_set_convrate(client, data, 500);	/* 500ms; 2Hz conversion rate */
 	if (lm90_read_reg(client, LM90_REG_R_CONFIG1, &config) < 0) {
 		dev_warn(&client->dev, "Initialization failed!\n");
 		return;
@@ -1266,6 +1348,9 @@ static int lm90_probe(struct i2c_client *new_client,
 	/* Set chip capabilities */
 	data->flags = lm90_params[data->kind].flags;
 
+	/* Set maximum conversion rate */
+	data->max_convrate = lm90_params[data->kind].max_convrate;
+
 	/* Initialize the LM90 chip */
 	lm90_init_client(new_client);
 
@@ -1327,6 +1412,8 @@ static int lm90_remove(struct i2c_client *client)
 	lm90_remove_files(client, data);
 
 	/* Restore initial configuration */
+	i2c_smbus_write_byte_data(client, LM90_REG_W_CONVRATE,
+				  data->convrate_orig);
 	i2c_smbus_write_byte_data(client, LM90_REG_W_CONFIG1,
 				  data->config_orig);