power: supply: qcom_battmgr: support disabling charge control

Existing userspace (in particular, upower) disables charge control by
setting the start threshold to 0 and the stop threshold to 100.

Handle that by actually setting the enable bit to 0 when a start
threshold of 0 was requested.

Fixes: cc3e883a0625 ("power: supply: qcom_battmgr: Add charge control support")
Signed-off-by: Val Packett <[e-mail]>
Link: https://patch.msgid.link/[e-mail]
Signed-off-by: Sebastian Reichel <[e-mail]>

drivers/power/supply/qcom_battmgr.c

···
 	unsigned int capacity_warning;
 	unsigned int cycle_count;
 	unsigned int charge_count;
+	bool charge_ctrl_enable;
 	unsigned int charge_ctrl_start;
 	unsigned int charge_ctrl_end;
 	char model_number[BATTMGR_STRING_LEN];
···
 }
 
 static int qcom_battmgr_set_charge_control(struct qcom_battmgr *battmgr,
-					   u32 target_soc, u32 delta_soc)
+					   bool enable, u32 target_soc, u32 delta_soc)
 {
 	struct qcom_battmgr_charge_ctrl_request request = {
 		.hdr.owner = cpu_to_le32(PMIC_GLINK_OWNER_BATTMGR),
 		.hdr.type = cpu_to_le32(PMIC_GLINK_REQ_RESP),
 		.hdr.opcode = cpu_to_le32(BATTMGR_CHG_CTRL_LIMIT_EN),
-		.enable = cpu_to_le32(1),
+		.enable = cpu_to_le32(enable),
 		.target_soc = cpu_to_le32(target_soc),
 		.delta_soc = cpu_to_le32(delta_soc),
 	};
···
 {
 	u32 target_soc, delta_soc;
 	int ret;
+	bool enable = start_soc != 0;
 
 	start_soc = clamp(start_soc, CHARGE_CTRL_START_THR_MIN, CHARGE_CTRL_START_THR_MAX);
 
···
 	}
 
 	mutex_lock(&battmgr->lock);
-	ret = qcom_battmgr_set_charge_control(battmgr, target_soc, delta_soc);
+	ret = qcom_battmgr_set_charge_control(battmgr, enable, target_soc, delta_soc);
 	mutex_unlock(&battmgr->lock);
 	if (!ret) {
+		battmgr->info.charge_ctrl_enable = enable;
 		battmgr->info.charge_ctrl_start = start_soc;
 		battmgr->info.charge_ctrl_end = target_soc;
 	}
···
 {
 	u32 delta_soc = CHARGE_CTRL_DELTA_SOC;
 	int ret;
+	bool enable = battmgr->info.charge_ctrl_enable;
 
 	end_soc = clamp(end_soc, CHARGE_CTRL_END_THR_MIN, CHARGE_CTRL_END_THR_MAX);
 
···
 		delta_soc = end_soc - battmgr->info.charge_ctrl_start;
 
 	mutex_lock(&battmgr->lock);
-	ret = qcom_battmgr_set_charge_control(battmgr, end_soc, delta_soc);
+	ret = qcom_battmgr_set_charge_control(battmgr, enable, end_soc, delta_soc);
 	mutex_unlock(&battmgr->lock);
 	if (!ret) {
 		battmgr->info.charge_ctrl_start = end_soc - delta_soc;