hwmon: (lm90) Read limit registers only once

Read limit registers only once at startup or after errors to improve
driver performance.
Signed-off-by: Guenter Roeck <linux@roeck-us.net>

drivers/hwmon/lm90.c

@@ -508,79 +508,48 @@ static void lm90_set_convrate(struct i2c_client *client, struct lm90_data *data,
 	data->update_interval = DIV_ROUND_CLOSEST(update_interval, 64);
 }
 
-static struct lm90_data *lm90_update_device(struct device *dev)
+static int lm90_update_limits(struct device *dev)
 {
 	struct lm90_data *data = dev_get_drvdata(dev);
 	struct i2c_client *client = data->client;
-	unsigned long next_update;
-	int val = 0;
-
-	mutex_lock(&data->update_lock);
-
-	next_update = data->last_updated +
-		      msecs_to_jiffies(data->update_interval);
-	if (time_after(jiffies, next_update) || !data->valid) {
-		dev_dbg(&client->dev, "Updating lm90 data.\n");
-		val = lm90_read_reg(client, LM90_REG_R_LOCAL_LOW);
-		if (val < 0)
-			goto error;
-		data->temp8[LOCAL_LOW] = val;
-
-		val = lm90_read_reg(client, LM90_REG_R_LOCAL_HIGH);
-		if (val < 0)
-			goto error;
-		data->temp8[LOCAL_HIGH] = val;
+	int val;
 
 	val = lm90_read_reg(client, LM90_REG_R_LOCAL_CRIT);
 	if (val < 0)
-			goto error;
+		return val;
 	data->temp8[LOCAL_CRIT] = val;
 
 	val = lm90_read_reg(client, LM90_REG_R_REMOTE_CRIT);
 	if (val < 0)
-			goto error;
+		return val;
 	data->temp8[REMOTE_CRIT] = val;
+
 	val = lm90_read_reg(client, LM90_REG_R_TCRIT_HYST);
 	if (val < 0)
-			goto error;
+		return val;
 	data->temp_hyst = val;
 
-		if (data->reg_local_ext) {
-			val = lm90_read16(client, LM90_REG_R_LOCAL_TEMP,
-					  data->reg_local_ext);
-			if (val < 0)
-				goto error;
-			data->temp11[LOCAL_TEMP] = val;
-		} else {
-			val = lm90_read_reg(client, LM90_REG_R_LOCAL_TEMP);
-			if (val < 0)
-				goto error;
-			data->temp11[LOCAL_TEMP] = val << 8;
-		}
-		val = lm90_read16(client, LM90_REG_R_REMOTE_TEMPH,
-				  LM90_REG_R_REMOTE_TEMPL);
-		if (val < 0)
-			goto error;
-		data->temp11[REMOTE_TEMP] = val;
-
 	lm90_read_reg(client, LM90_REG_R_REMOTE_LOWH);
 	if (val < 0)
-			goto error;
+		return val;
 	data->temp11[REMOTE_LOW] = val << 8;
+
 	if (data->flags & LM90_HAVE_REM_LIMIT_EXT) {
 		val = lm90_read_reg(client, LM90_REG_R_REMOTE_LOWL);
 		if (val < 0)
-				goto error;
+			return val;
 		data->temp11[REMOTE_LOW] |= val;
 	}
+
 	val = lm90_read_reg(client, LM90_REG_R_REMOTE_HIGHH);
 	if (val < 0)
-			goto error;
+		return val;
 	data->temp11[REMOTE_HIGH] = val << 8;
+
 	if (data->flags & LM90_HAVE_REM_LIMIT_EXT) {
 		val = lm90_read_reg(client, LM90_REG_R_REMOTE_HIGHL);
 		if (val < 0)
-				goto error;
+			return val;
 		data->temp11[REMOTE_HIGH] |= val;
 	}
 
@@ -588,54 +557,118 @@ static struct lm90_data *lm90_update_device(struct device *dev)
 		val = lm90_read16(client, LM90_REG_R_REMOTE_OFFSH,
 				  LM90_REG_R_REMOTE_OFFSL);
 		if (val < 0)
-				goto error;
+			return val;
 		data->temp11[REMOTE_OFFSET] = val;
 	}
+
 	if (data->flags & LM90_HAVE_EMERGENCY) {
 		val = lm90_read_reg(client, MAX6659_REG_R_LOCAL_EMERG);
 		if (val < 0)
-				goto error;
+			return val;
 		data->temp8[LOCAL_EMERG] = val;
+
 		val = lm90_read_reg(client, MAX6659_REG_R_REMOTE_EMERG);
 		if (val < 0)
-				goto error;
+			return val;
 		data->temp8[REMOTE_EMERG] = val;
 	}
-		val = lm90_read_reg(client, LM90_REG_R_STATUS);
-		if (val < 0)
-			goto error;
-		data->alarms = val;	/* lower 8 bit of alarms */
 
 	if (data->kind == max6696) {
 		val = lm90_select_remote_channel(client, data, 1);
 		if (val < 0)
-				goto error;
+			return val;
 
 		val = lm90_read_reg(client, LM90_REG_R_REMOTE_CRIT);
 		if (val < 0)
-				goto error;
+			return val;
 		data->temp8[REMOTE2_CRIT] = val;
 
 		val = lm90_read_reg(client, MAX6659_REG_R_REMOTE_EMERG);
 		if (val < 0)
-				goto error;
+			return val;
 		data->temp8[REMOTE2_EMERG] = val;
 
+		val = lm90_read_reg(client, LM90_REG_R_REMOTE_LOWH);
+		if (val < 0)
+			return val;
+		data->temp11[REMOTE2_LOW] = val << 8;
+
+		val = lm90_read_reg(client, LM90_REG_R_REMOTE_HIGHH);
+		if (val < 0)
+			return val;
+		data->temp11[REMOTE2_HIGH] = val << 8;
+
+		lm90_select_remote_channel(client, data, 0);
+	}
+
+	return 0;
+}
+
+static struct lm90_data *lm90_update_device(struct device *dev)
+{
+	struct lm90_data *data = dev_get_drvdata(dev);
+	struct i2c_client *client = data->client;
+	unsigned long next_update;
+	int val = 0;
+
+	mutex_lock(&data->update_lock);
+
+	if (!data->valid) {
+		val = lm90_update_limits(dev);
+		if (val < 0)
+			goto error;
+	}
+
+	next_update = data->last_updated +
+		      msecs_to_jiffies(data->update_interval);
+	if (time_after(jiffies, next_update) || !data->valid) {
+		dev_dbg(&client->dev, "Updating lm90 data.\n");
+
+		data->valid = 0;
+
+		val = lm90_read_reg(client, LM90_REG_R_LOCAL_LOW);
+		if (val < 0)
+			goto error;
+		data->temp8[LOCAL_LOW] = val;
+
+		val = lm90_read_reg(client, LM90_REG_R_LOCAL_HIGH);
+		if (val < 0)
+			goto error;
+		data->temp8[LOCAL_HIGH] = val;
+
+		if (data->reg_local_ext) {
+			val = lm90_read16(client, LM90_REG_R_LOCAL_TEMP,
+					  data->reg_local_ext);
+			if (val < 0)
+				goto error;
+			data->temp11[LOCAL_TEMP] = val;
+		} else {
+			val = lm90_read_reg(client, LM90_REG_R_LOCAL_TEMP);
+			if (val < 0)
+				goto error;
+			data->temp11[LOCAL_TEMP] = val << 8;
+		}
 		val = lm90_read16(client, LM90_REG_R_REMOTE_TEMPH,
 				  LM90_REG_R_REMOTE_TEMPL);
 		if (val < 0)
 			goto error;
-			data->temp11[REMOTE2_TEMP] = val;
+		data->temp11[REMOTE_TEMP] = val;
 
-			val = lm90_read_reg(client, LM90_REG_R_REMOTE_LOWH);
+		val = lm90_read_reg(client, LM90_REG_R_STATUS);
 		if (val < 0)
 			goto error;
-			data->temp11[REMOTE2_LOW] = val << 8;
+		data->alarms = val;	/* lower 8 bit of alarms */
 
-			val = lm90_read_reg(client, LM90_REG_R_REMOTE_HIGHH);
+		if (data->kind == max6696) {
+			val = lm90_select_remote_channel(client, data, 1);
 			if (val < 0)
 				goto error;
-			data->temp11[REMOTE2_HIGH] = val << 8;
+
+			val = lm90_read16(client, LM90_REG_R_REMOTE_TEMPH,
+					  LM90_REG_R_REMOTE_TEMPL);
+			if (val < 0)
+				goto error;
+			data->temp11[REMOTE2_TEMP] = val;
 
 			lm90_select_remote_channel(client, data, 0);