power: supply: core: Parse battery chemistry/technology

This extends the struct power_supply_battery_info with a
"technology" field makes the core DT parser optionally obtain
this from the device tree.
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Sebastian Reichel <sebastian.reichel@collabora.com>

drivers/power/supply/power_supply_core.c

@@ -571,6 +571,7 @@ int power_supply_get_battery_info(struct power_supply *psy,
 	int err, len, index;
 	const __be32 *list;
 
+	info->technology                     = POWER_SUPPLY_TECHNOLOGY_UNKNOWN;
 	info->energy_full_design_uwh         = -EINVAL;
 	info->charge_full_design_uah         = -EINVAL;
 	info->voltage_min_design_uv          = -EINVAL;
@@ -618,6 +619,25 @@ int power_supply_get_battery_info(struct power_supply *psy,
 	 * Documentation/power/power_supply_class.rst.
 	 */
 
+	err = of_property_read_string(battery_np, "device-chemistry", &value);
+	if (!err) {
+		if (!strcmp("nickel-cadmium", value))
+			info->technology = POWER_SUPPLY_TECHNOLOGY_NiCd;
+		else if (!strcmp("nickel-metal-hydride", value))
+			info->technology = POWER_SUPPLY_TECHNOLOGY_NiMH;
+		else if (!strcmp("lithium-ion", value))
+			/* Imprecise lithium-ion type */
+			info->technology = POWER_SUPPLY_TECHNOLOGY_LION;
+		else if (!strcmp("lithium-ion-polymer", value))
+			info->technology = POWER_SUPPLY_TECHNOLOGY_LIPO;
+		else if (!strcmp("lithium-ion-iron-phosphate", value))
+			info->technology = POWER_SUPPLY_TECHNOLOGY_LiFe;
+		else if (!strcmp("lithium-ion-manganese-oxide", value))
+			info->technology = POWER_SUPPLY_TECHNOLOGY_LiMn;
+		else
+			dev_warn(&psy->dev, "%s unknown battery type\n", value);
+	}
+
 	of_property_read_u32(battery_np, "energy-full-design-microwatt-hours",
 			     &info->energy_full_design_uwh);
 	of_property_read_u32(battery_np, "charge-full-design-microamp-hours",

include/linux/power_supply.h

@@ -352,6 +352,7 @@ struct power_supply_resistance_temp_table {
  */
 
 struct power_supply_battery_info {
+	unsigned int technology;	    /* from the enum above */
 	int energy_full_design_uwh;	    /* microWatt-hours */
 	int charge_full_design_uah;	    /* microAmp-hours */
 	int voltage_min_design_uv;	    /* microVolts */