power: supply: bq27xxx_battery: Expose a battery_reset attribute to userspace

Writing a '1' to this attribute should trigger a reset on battery
status and return the battery cycle count to 0. This attribute is
used to init a battery after replacement.

Signed-off-by: Sjoerd Simons <sjoerd.simons@collabora.co.uk>

drivers/power/supply/bq27xxx_battery.c

@@ -2150,8 +2150,66 @@ static enum power_supply_property charger_props[] = {
 	POWER_SUPPLY_PROP_ONLINE,
 };
 
+static ssize_t battery_reset_store(struct device *dev,
+				   struct device_attribute *attr,
+				   const char *buf,
+				   size_t count)
+{
+	bool reset;
+	int err;
+	struct bq27xxx_device_info *di = dev_get_drvdata(dev->parent);
+	struct bq27xxx_dm_buf_cache cache;
+	bool updated;
+
+	memset (&cache, 0, sizeof(cache));
+
+	err = kstrtobool(buf, &reset);
+	if (err)
+		return err;
+
+	if (!reset)
+		return count;
+
+	dev_info(di->dev, "RESET FOR %s\n", di->name);
+	cancel_delayed_work_sync(&di->work);
+
+	err = bq27xxx_battery_unseal(di);
+	if (err) {
+		count = err;
+		goto restart_delayed_work;
+	}
+
+	bq27xxx_battery_update_dm_reg(di, &cache, BQ27XXX_DM_CYCLE_COUNT, 0);
+	updated = bq27xxx_battery_cache_flush (di, &cache);
+
+	if (updated > 0 && !(di->opts & BQ27XXX_O_CFGUP)) {
+		dev_info(di->dev, "Resetting due to update options");
+		bq27xxx_write(di, BQ27XXX_REG_CTRL, BQ27XXX_RESET, false);
+		BQ27XXX_MSLEEP(300); /* reset time is not documented */
+	}
+
+	bq27xxx_battery_seal(di);
+
+restart_delayed_work:
+	schedule_delayed_work (&di->work, 0);
+	return count;
+}
+
+static DEVICE_ATTR_WO(battery_reset);
+
+static struct attribute *bq27xxx_battery_attrs[] = {
+	&dev_attr_battery_reset.attr,
+	NULL,
+};
+
+static const struct attribute_group bq27xxx_battery_attr_group = {
+	.attrs = bq27xxx_battery_attrs,
+};
+
+
 int bq27xxx_battery_setup(struct bq27xxx_device_info *di)
 {
+	int ret;
 	struct power_supply_desc *psy_desc, *psy_desc_charger;
 	struct power_supply_config psy_cfg = {
 		.of_node = di->dev->of_node,
@@ -2183,6 +2241,13 @@ int bq27xxx_battery_setup(struct bq27xxx_device_info *di)
 		return PTR_ERR(di->bat);
 	}
 
+	ret = sysfs_create_group(&di->bat->dev.kobj,
+				 &bq27xxx_battery_attr_group);
+	if (ret) {
+		dev_err(&di->bat->dev, "failed to create sysfs files\n");
+		return ret;
+	}
+
 	/* TODO only allocate charger iff there is one, probably via a dt
 	 * property */
 	psy_desc_charger = devm_kzalloc(di->dev, sizeof(*psy_desc_charger), GFP_KERNEL);