power: supply: sbs-battery: add POWER_SUPPLY_PROP_CAPACITY_ERROR_MARGIN support

Add support for reporting the MaxError register from
battery fuel gauges following the smart battery standard.

Reviewed-by: Emil Velikov <emil.velikov@collabora.com>
Signed-off-by: Sebastian Reichel <sebastian.reichel@collabora.com>

drivers/power/supply/sbs-battery.c

@@ -26,6 +26,7 @@ enum {
 	REG_TEMPERATURE,
 	REG_VOLTAGE,
 	REG_CURRENT,
+	REG_MAX_ERR,
 	REG_CAPACITY,
 	REG_TIME_TO_EMPTY,
 	REG_TIME_TO_FULL,
@@ -85,6 +86,8 @@ static const struct chip_data {
 		SBS_DATA(POWER_SUPPLY_PROP_VOLTAGE_NOW, 0x09, 0, 20000),
 	[REG_CURRENT] =
 		SBS_DATA(POWER_SUPPLY_PROP_CURRENT_NOW, 0x0A, -32768, 32767),
+	[REG_MAX_ERR] =
+		SBS_DATA(POWER_SUPPLY_PROP_CAPACITY_ERROR_MARGIN, 0x0c, 0, 100),
 	[REG_CAPACITY] =
 		SBS_DATA(POWER_SUPPLY_PROP_CAPACITY, 0x0D, 0, 100),
 	[REG_REMAINING_CAPACITY] =
@@ -132,6 +135,7 @@ static enum power_supply_property sbs_properties[] = {
 	POWER_SUPPLY_PROP_VOLTAGE_NOW,
 	POWER_SUPPLY_PROP_CURRENT_NOW,
 	POWER_SUPPLY_PROP_CAPACITY,
+	POWER_SUPPLY_PROP_CAPACITY_ERROR_MARGIN,
 	POWER_SUPPLY_PROP_TEMP,
 	POWER_SUPPLY_PROP_TIME_TO_EMPTY_AVG,
 	POWER_SUPPLY_PROP_TIME_TO_FULL_AVG,
@@ -676,6 +680,7 @@ static int sbs_get_property(struct power_supply *psy,
 	case POWER_SUPPLY_PROP_VOLTAGE_MIN_DESIGN:
 	case POWER_SUPPLY_PROP_VOLTAGE_MAX_DESIGN:
 	case POWER_SUPPLY_PROP_CAPACITY:
+	case POWER_SUPPLY_PROP_CAPACITY_ERROR_MARGIN:
 		ret = sbs_get_property_index(client, psp);
 		if (ret < 0)
 			break;