power: supply: sbs-battery: cache constant string properties

Currently sbs-battery supports three string properties -
manufacturer, model_name, and chemistry. Buffers for those
properties are currently defined as global variables.

This patch moves those global variables into struct sbs_info
and cache/reuse them as they are all constant values.
Signed-off-by: Ikjoon Jang <ikjn@chromium.org>
Tested-by: Hsin-Yi Wang <hsinyi@chromium.org>
Signed-off-by: Sebastian Reichel <sebastian.reichel@collabora.com>

drivers/power/supply/sbs-battery.c

@@ -189,6 +189,14 @@ static const enum power_supply_property sbs_properties[] = {
 /* Supports special manufacturer commands from TI BQ20Z65 and BQ20Z75 IC. */
 #define SBS_FLAGS_TI_BQ20ZX5		BIT(0)
 
+static const enum power_supply_property string_properties[] = {
+	POWER_SUPPLY_PROP_TECHNOLOGY,
+	POWER_SUPPLY_PROP_MANUFACTURER,
+	POWER_SUPPLY_PROP_MODEL_NAME,
+};
+
+#define NR_STRING_BUFFERS	ARRAY_SIZE(string_properties)
+
 struct sbs_info {
 	struct i2c_client		*client;
 	struct power_supply		*power_supply;
@@ -202,11 +210,32 @@ struct sbs_info {
 	struct delayed_work		work;
 	struct mutex			mode_lock;
 	u32				flags;
+	int				technology;
+	char				strings[NR_STRING_BUFFERS][I2C_SMBUS_BLOCK_MAX + 1];
 };
 
-static char model_name[I2C_SMBUS_BLOCK_MAX + 1];
-static char manufacturer[I2C_SMBUS_BLOCK_MAX + 1];
-static char chemistry[I2C_SMBUS_BLOCK_MAX + 1];
+static char *sbs_get_string_buf(struct sbs_info *chip,
+				enum power_supply_property psp)
+{
+	int i = 0;
+
+	for (i = 0; i < NR_STRING_BUFFERS; i++)
+		if (string_properties[i] == psp)
+			return chip->strings[i];
+
+	return ERR_PTR(-EINVAL);
+}
+
+static void sbs_invalidate_cached_props(struct sbs_info *chip)
+{
+	int i = 0;
+
+	chip->technology = -1;
+
+	for (i = 0; i < NR_STRING_BUFFERS; i++)
+		chip->strings[i][0] = 0;
+}
+
 static bool force_load;
 
 static int sbs_read_word_data(struct i2c_client *client, u8 address);
@@ -244,6 +273,7 @@ static int sbs_update_presence(struct sbs_info *chip, bool is_present)
 		chip->is_present = false;
 		/* Disable PEC when no device is present */
 		client->flags &= ~I2C_CLIENT_PEC;
+		sbs_invalidate_cached_props(chip);
 		return 0;
 	}
 
@@ -640,17 +670,45 @@ static int sbs_get_battery_property(struct i2c_client *client,
 	return 0;
 }
 
-static int sbs_get_battery_string_property(struct i2c_client *client,
-	int reg_offset, enum power_supply_property psp, char *val)
+static int sbs_get_property_index(struct i2c_client *client,
+	enum power_supply_property psp)
 {
-	s32 ret;
+	int count;
 
-	ret = sbs_read_string_data(client, sbs_data[reg_offset].addr, val);
+	for (count = 0; count < ARRAY_SIZE(sbs_data); count++)
+		if (psp == sbs_data[count].psp)
+			return count;
 
-	if (ret < 0)
-		return ret;
+	dev_warn(&client->dev,
+		"%s: Invalid Property - %d\n", __func__, psp);
 
-	return 0;
+	return -EINVAL;
+}
+
+static const char *sbs_get_constant_string(struct sbs_info *chip,
+			enum power_supply_property psp)
+{
+	int ret;
+	char *buf;
+	u8 addr;
+
+	buf = sbs_get_string_buf(chip, psp);
+	if (IS_ERR(buf))
+		return buf;
+
+	if (!buf[0]) {
+		ret = sbs_get_property_index(chip->client, psp);
+		if (ret < 0)
+			return ERR_PTR(ret);
+
+		addr = sbs_data[ret].addr;
+
+		ret = sbs_read_string_data(chip->client, addr, buf);
+		if (ret < 0)
+			return ERR_PTR(ret);
+	}
+
+	return buf;
 }
 
 static void  sbs_unit_adjustment(struct i2c_client *client,
@@ -773,48 +831,36 @@ static int sbs_get_battery_serial_number(struct i2c_client *client,
 	return 0;
 }
 
-static int sbs_get_property_index(struct i2c_client *client,
-	enum power_supply_property psp)
-{
-	int count;
-	for (count = 0; count < ARRAY_SIZE(sbs_data); count++)
-		if (psp == sbs_data[count].psp)
-			return count;
-
-	dev_warn(&client->dev,
-		"%s: Invalid Property - %d\n", __func__, psp);
-
-	return -EINVAL;
-}
-
-static int sbs_get_chemistry(struct i2c_client *client,
+static int sbs_get_chemistry(struct sbs_info *chip,
 		union power_supply_propval *val)
 {
-	enum power_supply_property psp = POWER_SUPPLY_PROP_TECHNOLOGY;
-	int ret;
+	const char *chemistry;
 
-	ret = sbs_get_property_index(client, psp);
-	if (ret < 0)
-		return ret;
+	if (chip->technology != -1) {
+		val->intval = chip->technology;
+		return 0;
+	}
 
-	ret = sbs_get_battery_string_property(client, ret, psp,
-					      chemistry);
-	if (ret < 0)
-		return ret;
+	chemistry = sbs_get_constant_string(chip, POWER_SUPPLY_PROP_TECHNOLOGY);
+
+	if (IS_ERR(chemistry))
+		return PTR_ERR(chemistry);
 
 	if (!strncasecmp(chemistry, "LION", 4))
-		val->intval = POWER_SUPPLY_TECHNOLOGY_LION;
+		chip->technology = POWER_SUPPLY_TECHNOLOGY_LION;
 	else if (!strncasecmp(chemistry, "LiP", 3))
-		val->intval = POWER_SUPPLY_TECHNOLOGY_LIPO;
+		chip->technology = POWER_SUPPLY_TECHNOLOGY_LIPO;
 	else if (!strncasecmp(chemistry, "NiCd", 4))
-		val->intval = POWER_SUPPLY_TECHNOLOGY_NiCd;
+		chip->technology = POWER_SUPPLY_TECHNOLOGY_NiCd;
 	else if (!strncasecmp(chemistry, "NiMH", 4))
-		val->intval = POWER_SUPPLY_TECHNOLOGY_NiMH;
+		chip->technology = POWER_SUPPLY_TECHNOLOGY_NiMH;
 	else
-		val->intval = POWER_SUPPLY_TECHNOLOGY_UNKNOWN;
+		chip->technology = POWER_SUPPLY_TECHNOLOGY_UNKNOWN;
+
+	if (chip->technology == POWER_SUPPLY_TECHNOLOGY_UNKNOWN)
+		dev_warn(&chip->client->dev, "Unknown chemistry: %s\n", chemistry);
 
-	if (val->intval == POWER_SUPPLY_TECHNOLOGY_UNKNOWN)
-		dev_warn(&client->dev, "Unknown chemistry: %s\n", chemistry);
+	val->intval = chip->technology;
 
 	return 0;
 }
@@ -858,6 +904,7 @@ static int sbs_get_property(struct power_supply *psy,
 	int ret = 0;
 	struct sbs_info *chip = power_supply_get_drvdata(psy);
 	struct i2c_client *client = chip->client;
+	const char *str;
 
 	if (chip->gpio_detect) {
 		ret = gpiod_get_value_cansleep(chip->gpio_detect);
@@ -883,7 +930,7 @@ static int sbs_get_property(struct power_supply *psy,
 		break;
 
 	case POWER_SUPPLY_PROP_TECHNOLOGY:
-		ret = sbs_get_chemistry(client, val);
+		ret = sbs_get_chemistry(chip, val);
 		if (ret < 0)
 			break;
 
@@ -935,23 +982,12 @@ static int sbs_get_property(struct power_supply *psy,
 		break;
 
 	case POWER_SUPPLY_PROP_MODEL_NAME:
-		ret = sbs_get_property_index(client, psp);
-		if (ret < 0)
-			break;
-
-		ret = sbs_get_battery_string_property(client, ret, psp,
-						      model_name);
-		val->strval = model_name;
-		break;
-
 	case POWER_SUPPLY_PROP_MANUFACTURER:
-		ret = sbs_get_property_index(client, psp);
-		if (ret < 0)
-			break;
-
-		ret = sbs_get_battery_string_property(client, ret, psp,
-						      manufacturer);
-		val->strval = manufacturer;
+		str = sbs_get_constant_string(chip, psp);
+		if (IS_ERR(str))
+			ret = PTR_ERR(str);
+		else
+			val->strval = str;
 		break;
 
 	case POWER_SUPPLY_PROP_MANUFACTURE_YEAR:
@@ -1098,6 +1134,7 @@ static int sbs_probe(struct i2c_client *client)
 	psy_cfg.of_node = client->dev.of_node;
 	psy_cfg.drv_data = chip;
 	chip->last_state = POWER_SUPPLY_STATUS_UNKNOWN;
+	sbs_invalidate_cached_props(chip);
 	mutex_init(&chip->mode_lock);
 
 	/* use pdata if available, fall back to DT properties,