HID: logitech-hidpp: Don't use the USB serial for USB devices

For devices that support the 0x0003 feature (Device Information) version 4,
set the serial based on the output of that feature, rather than relying
on the usbhid code setting the USB serial.

This should allow the serial when connected through USB to (nearly)
match the one when connected through a unifying receiver.

For example, on the serials on a G903 wired/wireless mouse:
- Unifying: 4067-e8-ce-cd-45
- USB before patch: 017C385C3837
- USB after patch: c086-e8-ce-cd-45

Signed-off-by: Bastien Nocera <hadess@hadess.net>
Link: https://lore.kernel.org/r/20230302130117.3975-1-hadess@hadess.net
Signed-off-by: Benjamin Tissoires <benjamin.tissoires@redhat.com>

1 files changed, 51 insertions, 0 deletions

diff --git a/drivers/hid/hid-logitech-hidpp.c b/drivers/hid/hid-logitech-hidpp.c
index 5fc88a063297..66380876937f 100644
--- a/drivers/hid/hid-logitech-hidpp.c
+++ b/drivers/hid/hid-logitech-hidpp.c
@@ -948,6 +948,55 @@ print_version:
 }
 
 /* -------------------------------------------------------------------------- */
+/* 0x0003: Device Information                                                 */
+/* -------------------------------------------------------------------------- */
+
+#define HIDPP_PAGE_DEVICE_INFORMATION			0x0003
+
+#define CMD_GET_DEVICE_INFO				0x00
+
+static int hidpp_get_serial(struct hidpp_device *hidpp, u32 *serial)
+{
+	struct hidpp_report response;
+	u8 feature_type;
+	u8 feature_index;
+	int ret;
+
+	ret = hidpp_root_get_feature(hidpp, HIDPP_PAGE_DEVICE_INFORMATION,
+				     &feature_index,
+				     &feature_type);
+	if (ret)
+		return ret;
+
+	ret = hidpp_send_fap_command_sync(hidpp, feature_index,
+					  CMD_GET_DEVICE_INFO,
+					  NULL, 0, &response);
+	if (ret)
+		return ret;
+
+	/* See hidpp_unifying_get_serial() */
+	*serial = *((u32 *)&response.rap.params[1]);
+	return 0;
+}
+
+static int hidpp_serial_init(struct hidpp_device *hidpp)
+{
+	struct hid_device *hdev = hidpp->hid_dev;
+	u32 serial;
+	int ret;
+
+	ret = hidpp_get_serial(hidpp, &serial);
+	if (ret)
+		return ret;
+
+	snprintf(hdev->uniq, sizeof(hdev->uniq), "%04x-%4phD",
+		 hdev->product, &serial);
+	dbg_hid("HID++ DeviceInformation: Got serial: %s\n", hdev->uniq);
+
+	return 0;
+}
+
+/* -------------------------------------------------------------------------- */
 /* 0x0005: GetDeviceNameType                                                  */
 /* -------------------------------------------------------------------------- */
 
@@ -4210,6 +4259,8 @@ static int hidpp_probe(struct hid_device *hdev, const struct hid_device_id *id)
 
 	if (hidpp->quirks & HIDPP_QUIRK_UNIFYING)
 		hidpp_unifying_init(hidpp);
+	else if (hid_is_usb(hidpp->hid_dev))
+		hidpp_serial_init(hidpp);
 
 	connected = hidpp_root_get_protocol_version(hidpp) == 0;
 	atomic_set(&hidpp->connected, connected);