[PATCH 6/7] power: supply: sbs-battery: add ability to disable charger broadcasts

[Jean-Francois Dagenais <jeff.dagenais@gmail.com>]

In certain designs, it is possible to add a battery on a populated i2c
bus without an sbs compliant charger. In that case, the battery will
un-necessarily and sometimes un-desirably master the bus trying to write
info in the charger.

It is observed in many occasion that these battery "broadcasts" are even
corrupting other ongoing master to slave communication. I.e. the
multi-master support in the battery is inadequate.

Thankfully, the CHARGER_MODE bit allows designers to disable that SBS
battery behaviour.

This needs to be done once when the battery is first seen on the bus.

Signed-off-by: Jean-Francois Dagenais <jeff.dagenais@gmail.com>
---
 drivers/power/supply/sbs-battery.c | 39 +++++++++++++++++++++++++++---
 1 file changed, 36 insertions(+), 3 deletions(-)

diff --git a/drivers/power/supply/sbs-battery.c b/drivers/power/supply/sbs-battery.c
index 46c89dd05f46..fb116ab7752d 100644
--- a/drivers/power/supply/sbs-battery.c
+++ b/drivers/power/supply/sbs-battery.c
@@ -51,6 +51,7 @@ enum sbs_capacity_mode {
 	CAPACITY_MODE_AMPS = 0,
 	CAPACITY_MODE_WATTS = BATTERY_MODE_CAPACITY_MASK
 };
+#define BATTERY_MODE_CHARGER_MASK	(1<<14)
 
 /* manufacturer access defines */
 #define MANUFACTURER_ACCESS_STATUS	0x0006
@@ -157,6 +158,7 @@ struct sbs_info {
 	bool				is_present;
 	struct gpio_desc		*gpio_detect;
 	bool				enable_detection;
+	bool				charger_broadcasts;
 	int				last_state;
 	int				poll_time;
 	u32				i2c_retry_count;
@@ -596,6 +598,34 @@ static int sbs_get_property_index(struct i2c_client *client,
 	return -EINVAL;
 }
 
+static void sbs_disable_charger_broadcasts(struct sbs_info *chip)
+{
+	int val = sbs_read_word_data(chip->client, BATTERY_MODE_OFFSET);
+	if (val < 0)
+		goto exit;
+
+	val |= BATTERY_MODE_CHARGER_MASK;
+
+	val = sbs_write_word_data(chip->client, BATTERY_MODE_OFFSET, val);
+
+exit:
+	if (val < 0)
+		dev_err(&chip->client->dev,
+			"Failed to disable charger broadcasting: %d\n", val);
+	else
+		dev_dbg(&chip->client->dev, "%s\n", __func__);
+}
+
+static void sbs_set_is_present(struct sbs_info *chip, bool is_present)
+{
+	dev_dbg(&chip->client->dev, "%s %d\n", __func__, is_present);
+
+	if (!chip->is_present && is_present && !chip->charger_broadcasts)
+		sbs_disable_charger_broadcasts(chip);
+
+	chip->is_present = is_present;
+}
+
 static int sbs_get_property(struct power_supply *psy,
 	enum power_supply_property psp,
 	union power_supply_propval *val)
@@ -610,7 +640,7 @@ static int sbs_get_property(struct power_supply *psy,
 			return ret;
 		if (psp == POWER_SUPPLY_PROP_PRESENT) {
 			val->intval = ret;
-			chip->is_present = val->intval;
+			sbs_set_is_present(chip, val->intval);
 			return 0;
 		}
 		if (ret == 0)
@@ -706,7 +736,7 @@ static int sbs_get_property(struct power_supply *psy,
 
 	if (!chip->gpio_detect &&
 		chip->is_present != (ret >= 0)) {
-		chip->is_present = (ret >= 0);
+		sbs_set_is_present(chip, ret >= 0);
 		power_supply_changed(chip->power_supply);
 	}
 
@@ -737,7 +767,7 @@ static void sbs_supply_changed(struct sbs_info *chip)
 	ret = gpiod_get_value_cansleep(chip->gpio_detect);
 	if (ret < 0)
 		return;
-	chip->is_present = ret;
+	sbs_set_is_present(chip, ret);
 	power_supply_changed(battery);
 }
 
@@ -862,6 +892,9 @@ static int sbs_probe(struct i2c_client *client,
 	force_load = of_property_read_bool(client->dev.of_node,
 					   "sbs,force-load");
 
+	chip->charger_broadcasts = !of_property_read_bool(client->dev.of_node,
+					"sbs,disable-charger-broadcasts");
+
 	chip->gpio_detect = devm_gpiod_get_optional(&client->dev,
 			"sbs,battery-detect", GPIOD_IN);
 	if (IS_ERR(chip->gpio_detect)) {
-- 
2.23.0