power: supply: olpc_battery: Add OLPC XO 1.75 support

The battery and the protocol are essentially the same as OLPC XO 1.5,
but the responses from the EC are LSB first.
Signed-off-by: Lubomir Rintel <lkundrak@v3.sk>
Acked-by: Pavel Machek <pavel@ucw.cz>
Signed-off-by: Sebastian Reichel <sebastian.reichel@collabora.com>

drivers/power/supply/olpc_battery.c

@@ -58,6 +58,7 @@ struct olpc_battery_data {
 	struct power_supply *olpc_bat;
 	char bat_serial[17];
 	bool new_proto;
+	bool little_endian;
 };
 
 /*********************************************************************
@@ -323,6 +324,14 @@ static int olpc_bat_get_voltage_max_design(union power_supply_propval *val)
 	return ret;
 }
 
+static u16 ecword_to_cpu(struct olpc_battery_data *data, u16 ec_word)
+{
+	if (data->little_endian)
+		return le16_to_cpu(ec_word);
+	else
+		return be16_to_cpu(ec_word);
+}
+
 /*********************************************************************
  *		Battery properties
  *********************************************************************/
@@ -395,7 +404,7 @@ static int olpc_bat_get_property(struct power_supply *psy,
 		if (ret)
 			return ret;
 
-		val->intval = (s16)be16_to_cpu(ec_word) * 9760L / 32;
+		val->intval = ecword_to_cpu(data, ec_word) * 9760L / 32;
 		break;
 	case POWER_SUPPLY_PROP_CURRENT_AVG:
 	case POWER_SUPPLY_PROP_CURRENT_NOW:
@@ -403,7 +412,7 @@ static int olpc_bat_get_property(struct power_supply *psy,
 		if (ret)
 			return ret;
 
-		val->intval = (s16)be16_to_cpu(ec_word) * 15625L / 120;
+		val->intval = ecword_to_cpu(data, ec_word) * 15625L / 120;
 		break;
 	case POWER_SUPPLY_PROP_CAPACITY:
 		ret = olpc_ec_cmd(EC_BAT_SOC, NULL, 0, &ec_byte, 1);
@@ -434,21 +443,21 @@ static int olpc_bat_get_property(struct power_supply *psy,
 		if (ret)
 			return ret;
 
-		val->intval = (s16)be16_to_cpu(ec_word) * 10 / 256;
+		val->intval = ecword_to_cpu(data, ec_word) * 10 / 256;
 		break;
 	case POWER_SUPPLY_PROP_TEMP_AMBIENT:
 		ret = olpc_ec_cmd(EC_AMB_TEMP, NULL, 0, (void *)&ec_word, 2);
 		if (ret)
 			return ret;
 
-		val->intval = (int)be16_to_cpu(ec_word) * 10 / 256;
+		val->intval = (int)ecword_to_cpu(data, ec_word) * 10 / 256;
 		break;
 	case POWER_SUPPLY_PROP_CHARGE_COUNTER:
 		ret = olpc_ec_cmd(EC_BAT_ACR, NULL, 0, (void *)&ec_word, 2);
 		if (ret)
 			return ret;
 
-		val->intval = (s16)be16_to_cpu(ec_word) * 6250 / 15;
+		val->intval = ecword_to_cpu(data, ec_word) * 6250 / 15;
 		break;
 	case POWER_SUPPLY_PROP_SERIAL_NUMBER:
 		ret = olpc_ec_cmd(EC_BAT_SERIAL, NULL, 0, (void *)&ser_buf, 8);
@@ -622,7 +631,11 @@ static int olpc_battery_probe(struct platform_device *pdev)
 	if (ret)
 		return ret;
 
-	if (ecver > 0x44) {
+	if (of_find_compatible_node(NULL, NULL, "olpc,xo1.75-ec")) {
+		/* XO 1.75 */
+		data->new_proto = true;
+		data->little_endian = true;
+	} else if (ecver > 0x44) {
 		/* XO 1 or 1.5 with a new EC firmware. */
 		data->new_proto = true;
 	} else if (ecver < 0x44) {