[PATCH v2 1/1] HID: logitech: add Bolt receiver support for Logitech HID++ devices

["Erik Håkansson" <erikhakan@gmail.com>]

Add Logitech Bolt receiver support to the Logitech HID receiver and
HID++ drivers.

Handle Bolt receiver notifications in hid-logitech-dj and add a
Bolt-specific initialization path in hid-logitech-hidpp, separate from
the existing Unifying receiver path.

This allows Bolt-connected HID++ devices to expose battery information
through the kernel power_supply path, so userspace tools can report
their battery status with the correct device model.

Tested with:
- Logitech MX Keys for Business via Bolt receiver

Reported-by: Kateřina Medvědová <k8ie@mcld.eu>
Link: https://lore.kernel.org/linux-input/345f7347-30a8-4568-a7a6-c70f54a52a8d@mcld.eu/
Signed-off-by: Erik Håkansson <erikhakan@gmail.com>
---
Changes in v2:
- Handle only the Bolt receiver/control interface in hid-logitech-dj and
  leave the other Bolt receiver interfaces to generic HID handling.
- Handle Bolt HID++ unpair notifications so child HID devices are removed
  after unpairing.

 drivers/hid/hid-logitech-dj.c    | 48 +++++++++++++++++++++++++++++---
 drivers/hid/hid-logitech-hidpp.c | 48 ++++++++++++++++++++++++++++++--
 2 files changed, 89 insertions(+), 7 deletions(-)

diff --git a/drivers/hid/hid-logitech-dj.c b/drivers/hid/hid-logitech-dj.c
index 9c574ab8b60b..571d5caa5bb5 100644
--- a/drivers/hid/hid-logitech-dj.c
+++ b/drivers/hid/hid-logitech-dj.c
@@ -121,6 +121,7 @@ enum recvr_type {
 	recvr_type_27mhz,
 	recvr_type_bluetooth,
 	recvr_type_dinovo,
+	recvr_type_bolt,
 };
 
 struct dj_report {
@@ -1156,6 +1157,10 @@ static void logi_hidpp_recv_queue_notif(struct hid_device *hdev,
 		logi_hidpp_dev_conn_notif_equad(hdev, hidpp_report, &workitem);
 		workitem.reports_supported |= STD_KEYBOARD;
 		break;
+	case 0x10:
+		device_type = "Bolt";
+		logi_hidpp_dev_conn_notif_equad(hdev, hidpp_report, &workitem);
+		break;
 	}
 
 	/* custom receiver device (eg. powerplay) */
@@ -1745,6 +1750,24 @@ static int logi_dj_hidpp_event(struct hid_device *hdev,
 
 	dj_dev = djrcv_dev->paired_dj_devices[device_index];
 
+	/*
+	 * Bolt receivers send explicit unpair notifications as HID++ events;
+	 * queue device removal when we receive one.
+	 */
+	if (djrcv_dev->type == recvr_type_bolt &&
+	    hidpp_report->report_id == REPORT_ID_HIDPP_SHORT &&
+	    hidpp_report->sub_id == REPORT_TYPE_NOTIF_DEVICE_UNPAIRED) {
+		struct dj_workitem workitem = {
+			.device_index = device_index,
+			.type = WORKITEM_TYPE_UNPAIRED,
+		};
+
+		kfifo_in(&djrcv_dev->notif_fifo, &workitem, sizeof(workitem));
+		schedule_work(&djrcv_dev->work);
+		spin_unlock_irqrestore(&djrcv_dev->lock, flags);
+		return false;
+	}
+
 	/*
 	 * With 27 MHz receivers, we do not get an explicit unpair event,
 	 * remove the old device if the user has paired a *different* device.
@@ -1884,6 +1907,9 @@ static int logi_dj_probe(struct hid_device *hdev,
 	 * treat these as logitech-dj interfaces then this causes input events
 	 * reported through this extra interface to not be reported correctly.
 	 * To avoid this, we treat these as generic-hid devices.
+	 *
+	 * Bolt receivers only use LOGITECH_DJ_INTERFACE_NUMBER for receiver
+	 * reporting. Treat all other Bolt interfaces as generic-hid devices.
 	 */
 	switch (id->driver_data) {
 	case recvr_type_dj:		no_dj_interfaces = 3; break;
@@ -1897,10 +1923,20 @@ static int logi_dj_probe(struct hid_device *hdev,
 	}
 	if (hid_is_usb(hdev)) {
 		intf = to_usb_interface(hdev->dev.parent);
-		if (intf && intf->altsetting->desc.bInterfaceNumber >=
-							no_dj_interfaces) {
-			hdev->quirks |= HID_QUIRK_INPUT_PER_APP;
-			return hid_hw_start(hdev, HID_CONNECT_DEFAULT);
+		if (intf) {
+			bool generic_hid_interface;
+
+			if (id->driver_data == recvr_type_bolt)
+				generic_hid_interface =
+					intf->altsetting->desc.bInterfaceNumber !=
+					LOGITECH_DJ_INTERFACE_NUMBER;
+			else
+				generic_hid_interface =
+					intf->altsetting->desc.bInterfaceNumber >= no_dj_interfaces;
+			if (generic_hid_interface) {
+				hdev->quirks |= HID_QUIRK_INPUT_PER_APP;
+				return hid_hw_start(hdev, HID_CONNECT_DEFAULT);
+			}
 		}
 	}
 
@@ -2103,6 +2139,10 @@ static const struct hid_device_id logi_dj_receivers[] = {
 	  HID_USB_DEVICE(USB_VENDOR_ID_LOGITECH,
 		USB_DEVICE_ID_LOGITECH_NANO_RECEIVER_LIGHTSPEED_1_3),
 	 .driver_data = recvr_type_gaming_hidpp_ls_1_3},
+	{ /* Logitech Bolt receiver (0xc548) */
+	  HID_USB_DEVICE(USB_VENDOR_ID_LOGITECH,
+			 USB_DEVICE_ID_LOGITECH_BOLT_RECEIVER),
+	 .driver_data = recvr_type_bolt},
 	{ /* Logitech lightspeed receiver (0xc54d) */
 	  HID_USB_DEVICE(USB_VENDOR_ID_LOGITECH,
 		USB_DEVICE_ID_LOGITECH_NANO_RECEIVER_LIGHTSPEED_1_4),
diff --git a/drivers/hid/hid-logitech-hidpp.c b/drivers/hid/hid-logitech-hidpp.c
index 90b0184df777..0b5d0a322ae8 100644
--- a/drivers/hid/hid-logitech-hidpp.c
+++ b/drivers/hid/hid-logitech-hidpp.c
@@ -4161,8 +4161,50 @@ static int hidpp_initialize_battery(struct hidpp_device *hidpp)
 	return ret;
 }
 
+static bool hidpp_is_bolt_child(struct hid_device *hdev)
+{
+	struct device *parent = hdev->dev.parent;
+	struct hid_device *receiver_hdev;
+
+	if (!parent)
+		return false;
+
+	receiver_hdev = to_hid_device(parent);
+	return receiver_hdev->vendor == USB_VENDOR_ID_LOGITECH &&
+	       receiver_hdev->product == USB_DEVICE_ID_LOGITECH_BOLT_RECEIVER;
+}
+
+static int hidpp_bolt_init(struct hidpp_device *hidpp)
+{
+	struct hid_device *hdev = hidpp->hid_dev;
+	char *name;
+	int ret;
+
+	ret = hidpp_serial_init(hidpp);
+	if (ret)
+		return ret;
+
+	name = hidpp_get_device_name(hidpp);
+	if (!name)
+		return -EIO;
+
+	snprintf(hdev->name, sizeof(hdev->name), "%s", name);
+	dbg_hid("HID++ Bolt: Got name: %s\n", name);
+
+	kfree(name);
+	return 0;
+}
+
+static int hidpp_receiver_init(struct hidpp_device *hidpp)
+{
+	if (hidpp_is_bolt_child(hidpp->hid_dev))
+		return hidpp_bolt_init(hidpp);
+
+	return hidpp_unifying_init(hidpp);
+}
+
 /* Get name + serial for USB and Bluetooth HID++ devices */
-static void hidpp_non_unifying_init(struct hidpp_device *hidpp)
+static void hidpp_non_receiver_init(struct hidpp_device *hidpp)
 {
 	struct hid_device *hdev = hidpp->hid_dev;
 	char *name;
@@ -4510,9 +4552,9 @@ static int hidpp_probe(struct hid_device *hdev, const struct hid_device_id *id)
 
 	/* Get name + serial, store in hdev->name + hdev->uniq */
 	if (id->group == HID_GROUP_LOGITECH_DJ_DEVICE)
-		hidpp_unifying_init(hidpp);
+		hidpp_receiver_init(hidpp);
 	else
-		hidpp_non_unifying_init(hidpp);
+		hidpp_non_receiver_init(hidpp);
 
 	if (hidpp->quirks & HIDPP_QUIRK_DELAYED_INIT)
 		connect_mask &= ~HID_CONNECT_HIDINPUT;
-- 
2.55.0