[PATCH v4] hid-logitech-hidpp: read battery voltage from newer devices

[Pedro Vanzella <pedro@pedrovanzella.com>]

Newer Logitech mice report their battery voltage through feature 0x1001
instead of the battery levels through feature 0x1000.

When the device is brought up and we try to query the battery, figure
out if it supports the old or the new feature. If it supports the new
feature, record the feature index and read the battery voltage and
its status.

If everything went correctly, record the fact that we're capable
of querying battery voltage.

Note that the protocol only gives us the current voltage in millivolts.

Like we do for other ways of interacting with the battery for other
devices, refresh the battery status and notify the power supply
subsystem of the changes in voltage and status.

Signed-off-by: Pedro Vanzella <pedro@pedrovanzella.com>
---
 drivers/hid/hid-logitech-hidpp.c | 140 ++++++++++++++++++++++++++++++-
 1 file changed, 138 insertions(+), 2 deletions(-)

diff --git a/drivers/hid/hid-logitech-hidpp.c b/drivers/hid/hid-logitech-hidpp.c
index 0179f7ed77e5..5c9c3133d2ae 100644
--- a/drivers/hid/hid-logitech-hidpp.c
+++ b/drivers/hid/hid-logitech-hidpp.c
@@ -87,6 +87,7 @@ MODULE_PARM_DESC(disable_tap_to_click,
 #define HIDPP_CAPABILITY_HIDPP20_BATTERY	BIT(1)
 #define HIDPP_CAPABILITY_BATTERY_MILEAGE	BIT(2)
 #define HIDPP_CAPABILITY_BATTERY_LEVEL_STATUS	BIT(3)
+#define HIDPP_CAPABILITY_BATTERY_VOLTAGE	BIT(4)
 
 /*
  * There are two hidpp protocols in use, the first version hidpp10 is known
@@ -135,12 +136,14 @@ struct hidpp_report {
 struct hidpp_battery {
 	u8 feature_index;
 	u8 solar_feature_index;
+	u8 voltage_feature_index;
 	struct power_supply_desc desc;
 	struct power_supply *ps;
 	char name[64];
 	int status;
 	int capacity;
 	int level;
+	int voltage; /* in millivolts */
 	bool online;
 };
 
@@ -1219,6 +1222,122 @@ static int hidpp20_battery_event(struct hidpp_device *hidpp,
 	return 0;
 }
 
+/* -------------------------------------------------------------------------- */
+/* 0x1001: Battery voltage                                                    */
+/* -------------------------------------------------------------------------- */
+
+#define HIDPP_PAGE_BATTERY_VOLTAGE 0x1001
+
+#define CMD_BATTERY_VOLTAGE_GET_BATTERY_VOLTAGE 0x00
+
+static int hidpp20_battery_map_status_voltage(u8 data[3], int *voltage)
+{
+	int status;
+
+	switch (data[2]) {
+	case 0x00: /* discharging */
+		status = POWER_SUPPLY_STATUS_DISCHARGING;
+		break;
+	case 0x10: /* wireless charging */
+	case 0x80: /* charging */
+		status = POWER_SUPPLY_STATUS_CHARGING;
+		break;
+	case 0x81: /* fully charged */
+		status = POWER_SUPPLY_STATUS_FULL;
+		break;
+	default:
+		status = POWER_SUPPLY_STATUS_NOT_CHARGING;
+	}
+
+	*voltage = (data[0] << 8) + data[1];
+
+	return status;
+}
+
+static int hidpp20_battery_get_battery_voltage(struct hidpp_device *hidpp,
+					       u8 feature_index,
+					       int *status, int *voltage)
+{
+	struct hidpp_report response;
+	int ret;
+	u8 *params = (u8 *)response.fap.params;
+
+	ret = hidpp_send_fap_command_sync(hidpp, feature_index,
+					  CMD_BATTERY_VOLTAGE_GET_BATTERY_VOLTAGE,
+					  NULL, 0, &response);
+
+	if (ret > 0) {
+		hid_err(hidpp->hid_dev, "%s: received protocol error 0x%02x\n",
+			__func__, ret);
+		return -EPROTO;
+	}
+	if (ret)
+		return ret;
+
+	hidpp->capabilities |= HIDPP_CAPABILITY_BATTERY_VOLTAGE;
+
+	*status = hidpp20_battery_map_status_voltage(params, voltage);
+
+	return 0;
+}
+
+static int hidpp20_query_battery_voltage_info(struct hidpp_device *hidpp)
+{
+	u8 feature_type;
+	int ret;
+	int status, voltage;
+
+	if (hidpp->battery.voltage_feature_index == 0xff) {
+		ret = hidpp_root_get_feature(hidpp, HIDPP_PAGE_BATTERY_VOLTAGE,
+					     &hidpp->battery.voltage_feature_index,
+					     &feature_type);
+		if (ret)
+			return ret;
+	}
+
+	ret = hidpp20_battery_get_battery_voltage(hidpp,
+						  hidpp->battery.voltage_feature_index,
+						  &status, &voltage);
+
+	if (ret)
+		return ret;
+
+	hidpp->battery.status = status;
+	hidpp->battery.voltage = voltage;
+	hidpp->battery.online = status != POWER_SUPPLY_STATUS_NOT_CHARGING;
+
+	return 0;
+}
+
+static int hidpp20_battery_voltage_event(struct hidpp_device *hidpp,
+					 u8 *data, int size)
+{
+	struct hidpp_report *report = (struct hidpp_report *)data;
+	int status, voltage;
+	bool changed;
+
+	if (report->fap.feature_index != hidpp->battery.voltage_feature_index ||
+	    report->fap.funcindex_clientid !=
+		    EVENT_BATTERY_LEVEL_STATUS_BROADCAST)
+		return 0;
+
+	status = hidpp20_battery_map_status_voltage(report->fap.params,
+						    &voltage);
+
+	hidpp->battery.online = status != POWER_SUPPLY_STATUS_NOT_CHARGING;
+
+	changed = voltage != hidpp->battery.voltage ||
+		  status != hidpp->battery.status;
+
+	if (changed) {
+		hidpp->battery.voltage = voltage;
+		hidpp->battery.status = status;
+		if (hidpp->battery.ps)
+			power_supply_changed(hidpp->battery.ps);
+	}
+	return 0;
+}
+
 static enum power_supply_property hidpp_battery_props[] = {
 	POWER_SUPPLY_PROP_ONLINE,
 	POWER_SUPPLY_PROP_STATUS,
@@ -1228,6 +1347,7 @@ static enum power_supply_property hidpp_battery_props[] = {
 	POWER_SUPPLY_PROP_SERIAL_NUMBER,
 	0, /* placeholder for POWER_SUPPLY_PROP_CAPACITY, */
 	0, /* placeholder for POWER_SUPPLY_PROP_CAPACITY_LEVEL, */
+	0, /* placeholder for POWER_SUPPLY_PROP_VOLTAGE_NOW, */
 };
 
 static int hidpp_battery_get_property(struct power_supply *psy,
@@ -1265,6 +1385,9 @@ static int hidpp_battery_get_property(struct power_supply *psy,
 		case POWER_SUPPLY_PROP_SERIAL_NUMBER:
 			val->strval = hidpp->hid_dev->uniq;
 			break;
+		case POWER_SUPPLY_PROP_VOLTAGE_NOW:
+			val->intval = hidpp->battery.voltage;
+			break;
 		default:
 			ret = -EINVAL;
 			break;
@@ -3083,6 +3206,9 @@ static int hidpp_raw_hidpp_event(struct hidpp_device *hidpp, u8 *data,
 		ret = hidpp_solar_battery_event(hidpp, data, size);
 		if (ret != 0)
 			return ret;
+		ret = hidpp20_battery_voltage_event(hidpp, data, size);
+		if (ret != 0)
+			return ret;
 	}
 
 	if (hidpp->capabilities & HIDPP_CAPABILITY_HIDPP10_BATTERY) {
@@ -3204,12 +3330,16 @@ static int hidpp_initialize_battery(struct hidpp_device *hidpp)
 
 	hidpp->battery.feature_index = 0xff;
 	hidpp->battery.solar_feature_index = 0xff;
+	hidpp->battery.voltage_feature_index = 0xff;
 
 	if (hidpp->protocol_major >= 2) {
 		if (hidpp->quirks & HIDPP_QUIRK_CLASS_K750)
 			ret = hidpp_solar_request_battery_event(hidpp);
-		else
+		else {
 			ret = hidpp20_query_battery_info(hidpp);
+			if (ret)
+				ret = hidpp20_query_battery_voltage_info(hidpp);
+		}
 
 		if (ret)
 			return ret;
@@ -3234,7 +3364,7 @@ static int hidpp_initialize_battery(struct hidpp_device *hidpp)
 	if (!battery_props)
 		return -ENOMEM;
 
-	num_battery_props = ARRAY_SIZE(hidpp_battery_props) - 2;
+	num_battery_props = ARRAY_SIZE(hidpp_battery_props) - 3;
 
 	if (hidpp->capabilities & HIDPP_CAPABILITY_BATTERY_MILEAGE)
 		battery_props[num_battery_props++] =
@@ -3244,6 +3374,10 @@ static int hidpp_initialize_battery(struct hidpp_device *hidpp)
 		battery_props[num_battery_props++] =
 				POWER_SUPPLY_PROP_CAPACITY_LEVEL;
 
+	if (hidpp->capabilities & HIDPP_CAPABILITY_BATTERY_VOLTAGE)
+		battery_props[num_battery_props++] =
+			POWER_SUPPLY_PROP_VOLTAGE_NOW;
+
 	battery = &hidpp->battery;
 
 	n = atomic_inc_return(&battery_no) - 1;
@@ -3408,6 +3542,8 @@ static void hidpp_connect_event(struct hidpp_device *hidpp)
 			hidpp10_query_battery_status(hidpp);
 	} else if (hidpp->capabilities & HIDPP_CAPABILITY_HIDPP20_BATTERY) {
 		hidpp20_query_battery_info(hidpp);
+		if (hidpp->capabilities & HIDPP_CAPABILITY_BATTERY_VOLTAGE)
+			hidpp20_query_battery_voltage_info(hidpp);
 	}
 	if (hidpp->battery.ps)
 		power_supply_changed(hidpp->battery.ps);
-- 
2.23.0