HID: logitech-hidpp: Add support for ADC measurement feature

This is used in a number of Logitech headsets to report the voltage
of the battery.

Tested on a Logitech G935.

Signed-off-by: Bastien Nocera <hadess@hadess.net>
BugLink: https://bugzilla.kernel.org/show_bug.cgi?id=216483
Link: https://lore.kernel.org/r/20230302105555.51417-2-hadess@hadess.net
Signed-off-by: Benjamin Tissoires <benjamin.tissoires@redhat.com>

Author: hadess

drivers/hid/hid-logitech-hidpp.c

@@ -94,6 +94,7 @@ MODULE_PARM_DESC(disable_tap_to_click,
 #define HIDPP_CAPABILITY_HIDPP20_HI_RES_WHEEL	BIT(7)
 #define HIDPP_CAPABILITY_HIDPP20_HI_RES_SCROLL	BIT(8)
 #define HIDPP_CAPABILITY_HIDPP10_FAST_SCROLL	BIT(9)
+#define HIDPP_CAPABILITY_ADC_MEASUREMENT	BIT(10)
 
 #define lg_map_key_clear(c)  hid_map_usage_clear(hi, usage, bit, max, EV_KEY, (c))
 
@@ -145,6 +146,7 @@ struct hidpp_battery {
 	u8 feature_index;
 	u8 solar_feature_index;
 	u8 voltage_feature_index;
+	u8 adc_measurement_feature_index;
 	struct power_supply_desc desc;
 	struct power_supply *ps;
 	char name[64];
@@ -1790,6 +1792,162 @@ static int hidpp_set_wireless_feature_index(struct hidpp_device *hidpp)
 	return ret;
 }
 
+/* -------------------------------------------------------------------------- */
+/* 0x1f20: ADC measurement                                                    */
+/* -------------------------------------------------------------------------- */
+
+#define HIDPP_PAGE_ADC_MEASUREMENT 0x1f20
+
+#define CMD_ADC_MEASUREMENT_GET_ADC_MEASUREMENT 0x00
+
+#define EVENT_ADC_MEASUREMENT_STATUS_BROADCAST 0x00
+
+static int hidpp20_map_adc_measurement_1f20_capacity(struct hid_device *hid_dev, int voltage)
+{
+	/* NB: This voltage curve doesn't necessarily map perfectly to all
+	 * devices that implement the ADC_MEASUREMENT feature. This is because
+	 * there are a few devices that use different battery technology.
+	 *
+	 * Adapted from:
+	 * https://github.com/Sapd/HeadsetControl/blob/acd972be0468e039b93aae81221f20a54d2d60f7/src/devices/logitech_g633_g933_935.c#L44-L52
+	 */
+	static const int voltages[100] = {
+		4030, 4024, 4018, 4011, 4003, 3994, 3985, 3975, 3963, 3951,
+		3937, 3922, 3907, 3893, 3880, 3868, 3857, 3846, 3837, 3828,
+		3820, 3812, 3805, 3798, 3791, 3785, 3779, 3773, 3768, 3762,
+		3757, 3752, 3747, 3742, 3738, 3733, 3729, 3724, 3720, 3716,
+		3712, 3708, 3704, 3700, 3696, 3692, 3688, 3685, 3681, 3677,
+		3674, 3670, 3667, 3663, 3660, 3657, 3653, 3650, 3646, 3643,
+		3640, 3637, 3633, 3630, 3627, 3624, 3620, 3617, 3614, 3611,
+		3608, 3604, 3601, 3598, 3595, 3592, 3589, 3585, 3582, 3579,
+		3576, 3573, 3569, 3566, 3563, 3560, 3556, 3553, 3550, 3546,
+		3543, 3539, 3536, 3532, 3529, 3525, 3499, 3466, 3433, 3399,
+	};
+
+	int i;
+
+	if (voltage == 0)
+		return 0;
+
+	if (unlikely(voltage < 3400 || voltage >= 5000))
+		hid_warn_once(hid_dev,
+			      "%s: possibly using the wrong voltage curve\n",
+			      __func__);
+
+	for (i = 0; i < ARRAY_SIZE(voltages); i++) {
+		if (voltage >= voltages[i])
+			return ARRAY_SIZE(voltages) - i;
+	}
+
+	return 0;
+}
+
+static int hidpp20_map_adc_measurement_1f20(u8 data[3], int *voltage)
+{
+	int status;
+	u8 flags;
+
+	flags = data[2];
+
+	switch (flags) {
+	case 0x01:
+		status = POWER_SUPPLY_STATUS_DISCHARGING;
+		break;
+	case 0x03:
+		status = POWER_SUPPLY_STATUS_CHARGING;
+		break;
+	case 0x07:
+		status = POWER_SUPPLY_STATUS_FULL;
+		break;
+	case 0x0F:
+	default:
+		status = POWER_SUPPLY_STATUS_UNKNOWN;
+		break;
+	}
+
+	*voltage = get_unaligned_be16(data);
+
+	dbg_hid("Parsed 1f20 data as flag 0x%02x voltage %dmV\n",
+		flags, *voltage);
+
+	return status;
+}
+
+/* Return value is whether the device is online */
+static bool hidpp20_get_adc_measurement_1f20(struct hidpp_device *hidpp,
+						 u8 feature_index,
+						 int *status, int *voltage)
+{
+	struct hidpp_report response;
+	int ret;
+	u8 *params = (u8 *)response.fap.params;
+
+	*status = POWER_SUPPLY_STATUS_UNKNOWN;
+	*voltage = 0;
+	ret = hidpp_send_fap_command_sync(hidpp, feature_index,
+					  CMD_ADC_MEASUREMENT_GET_ADC_MEASUREMENT,
+					  NULL, 0, &response);
+
+	if (ret > 0) {
+		hid_dbg(hidpp->hid_dev, "%s: received protocol error 0x%02x\n",
+			__func__, ret);
+		return false;
+	}
+
+	*status = hidpp20_map_adc_measurement_1f20(params, voltage);
+	return true;
+}
+
+static int hidpp20_query_adc_measurement_info_1f20(struct hidpp_device *hidpp)
+{
+	u8 feature_type;
+
+	if (hidpp->battery.adc_measurement_feature_index == 0xff) {
+		int ret;
+
+		ret = hidpp_root_get_feature(hidpp, HIDPP_PAGE_ADC_MEASUREMENT,
+					     &hidpp->battery.adc_measurement_feature_index,
+					     &feature_type);
+		if (ret)
+			return ret;
+
+		hidpp->capabilities |= HIDPP_CAPABILITY_ADC_MEASUREMENT;
+	}
+
+	hidpp->battery.online = hidpp20_get_adc_measurement_1f20(hidpp,
+								 hidpp->battery.adc_measurement_feature_index,
+								 &hidpp->battery.status,
+								 &hidpp->battery.voltage);
+	hidpp->battery.capacity = hidpp20_map_adc_measurement_1f20_capacity(hidpp->hid_dev,
+									    hidpp->battery.voltage);
+
+	return 0;
+}
+
+static int hidpp20_adc_measurement_event_1f20(struct hidpp_device *hidpp,
+					    u8 *data, int size)
+{
+	struct hidpp_report *report = (struct hidpp_report *)data;
+	int status, voltage;
+
+	if (report->fap.feature_index != hidpp->battery.adc_measurement_feature_index ||
+		report->fap.funcindex_clientid != EVENT_ADC_MEASUREMENT_STATUS_BROADCAST)
+		return 0;
+
+	status = hidpp20_map_adc_measurement_1f20(report->fap.params, &voltage);
+
+	hidpp->battery.online = status != POWER_SUPPLY_STATUS_UNKNOWN;
+
+	if (voltage != hidpp->battery.voltage || status != hidpp->battery.status) {
+		hidpp->battery.status = status;
+		hidpp->battery.voltage = voltage;
+		hidpp->battery.capacity = hidpp20_map_adc_measurement_1f20_capacity(hidpp->hid_dev, voltage);
+		if (hidpp->battery.ps)
+			power_supply_changed(hidpp->battery.ps);
+	}
+	return 0;
+}
+
 /* -------------------------------------------------------------------------- */
 /* 0x2120: Hi-resolution scrolling                                            */
 /* -------------------------------------------------------------------------- */
@@ -3708,6 +3866,9 @@ static int hidpp_raw_hidpp_event(struct hidpp_device *hidpp, u8 *data,
 		ret = hidpp20_battery_voltage_event(hidpp, data, size);
 		if (ret != 0)
 			return ret;
+		ret = hidpp20_adc_measurement_event_1f20(hidpp, data, size);
+		if (ret != 0)
+			return ret;
 	}
 
 	if (hidpp->capabilities & HIDPP_CAPABILITY_HIDPP10_BATTERY) {
@@ -3831,6 +3992,7 @@ 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;
+	hidpp->battery.adc_measurement_feature_index = 0xff;
 
 	if (hidpp->protocol_major >= 2) {
 		if (hidpp->quirks & HIDPP_QUIRK_CLASS_K750)
@@ -3844,6 +4006,8 @@ static int hidpp_initialize_battery(struct hidpp_device *hidpp)
 				ret = hidpp20_query_battery_info_1004(hidpp);
 			if (ret)
 				ret = hidpp20_query_battery_voltage_info(hidpp);
+			if (ret)
+				ret = hidpp20_query_adc_measurement_info_1f20(hidpp);
 		}
 
 		if (ret)
@@ -3873,15 +4037,17 @@ static int hidpp_initialize_battery(struct hidpp_device *hidpp)
 
 	if (hidpp->capabilities & HIDPP_CAPABILITY_BATTERY_MILEAGE ||
 	    hidpp->capabilities & HIDPP_CAPABILITY_BATTERY_PERCENTAGE ||
-	    hidpp->capabilities & HIDPP_CAPABILITY_BATTERY_VOLTAGE)
+	    hidpp->capabilities & HIDPP_CAPABILITY_BATTERY_VOLTAGE ||
+	    hidpp->capabilities & HIDPP_CAPABILITY_ADC_MEASUREMENT)
 		battery_props[num_battery_props++] =
 				POWER_SUPPLY_PROP_CAPACITY;
 
 	if (hidpp->capabilities & HIDPP_CAPABILITY_BATTERY_LEVEL_STATUS)
 		battery_props[num_battery_props++] =
 				POWER_SUPPLY_PROP_CAPACITY_LEVEL;
 
-	if (hidpp->capabilities & HIDPP_CAPABILITY_BATTERY_VOLTAGE)
+	if (hidpp->capabilities & HIDPP_CAPABILITY_BATTERY_VOLTAGE ||
+	    hidpp->capabilities & HIDPP_CAPABILITY_ADC_MEASUREMENT)
 		battery_props[num_battery_props++] =
 			POWER_SUPPLY_PROP_VOLTAGE_NOW;
 
@@ -4054,6 +4220,8 @@ static void hidpp_connect_event(struct hidpp_device *hidpp)
 			hidpp20_query_battery_voltage_info(hidpp);
 		else if (hidpp->capabilities & HIDPP_CAPABILITY_UNIFIED_BATTERY)
 			hidpp20_query_battery_info_1004(hidpp);
+		else if (hidpp->capabilities & HIDPP_CAPABILITY_ADC_MEASUREMENT)
+			hidpp20_query_adc_measurement_info_1f20(hidpp);
 		else
 			hidpp20_query_battery_info_1000(hidpp);
 	}