// SPDX-License-Identifier: GPL-2.0-or-later/* *  HID driver for the HyperX QuadCast 2 microphone * *  The tap-to-mute button is handled entirely in the device firmware: it gates *  the audio internally and does not send the Telephony "Phone Mute" usage its *  own report descriptor advertises.  The resulting mute state is only reported *  through a vendor-defined collection, which hid-input cannot map, so the *  button is invisible to userspace. * *  Copyright (c) 2026 Benjamin Blume <benjaminblume@posteo.de> */ #include <linux/hid.h>#include <linux/input.h>#include <linux/module.h> #include "hid-ids.h" #define HYPERX_QC2_REPORT_ID	0x77#define HYPERX_QC2_EVENT_MUTE	0x06#define HYPERX_QC2_MUTE_LEN	3 struct hyperx_drvdata {	struct input_dev *input;	bool muted;	bool have_state;}; static int hyperx_input_configured(struct hid_device *hdev,				   struct hid_input *hi){	struct hyperx_drvdata *drvdata = hid_get_drvdata(hdev); 	/*	 * The device exposes several application collections.  Prefer the	 * telephony one, which already advertises KEY_MICMUTE, and fall back	 * to the first collection otherwise.	 */	if (!drvdata->input || test_bit(KEY_MICMUTE, hi->input->keybit)) {		drvdata->input = hi->input;		input_set_capability(drvdata->input, EV_KEY, KEY_MICMUTE);	} 	return 0;} static int hyperx_raw_event(struct hid_device *hdev, struct hid_report *report,			    u8 *data, int size){	struct hyperx_drvdata *drvdata = hid_get_drvdata(hdev);	bool muted; 	if (!(hdev->claimed & HID_CLAIMED_INPUT) || !drvdata->input)		return 0; 	if (size < HYPERX_QC2_MUTE_LEN || data[0] != HYPERX_QC2_REPORT_ID ||	    data[1] != HYPERX_QC2_EVENT_MUTE)		return 0; 	muted = data[2];	if (drvdata->have_state && muted == drvdata->muted)		return 0; 	drvdata->muted = muted;	drvdata->have_state = true; 	/*	 * The device reports the resulting absolute state, while KEY_MICMUTE is	 * a momentary key that userspace acts on as a toggle.  Emit one	 * keypress per state change.	 */	input_report_key(drvdata->input, KEY_MICMUTE, 1);	input_sync(drvdata->input);	input_report_key(drvdata->input, KEY_MICMUTE, 0);	input_sync(drvdata->input); 	return 0;} static int hyperx_probe(struct hid_device *hdev, const struct hid_device_id *id){	struct hyperx_drvdata *drvdata;	int ret; 	drvdata = devm_kzalloc(&hdev->dev, sizeof(*drvdata), GFP_KERNEL);	if (!drvdata)		return -ENOMEM; 	hid_set_drvdata(hdev, drvdata); 	ret = hid_parse(hdev);	if (ret)		return ret; 	return hid_hw_start(hdev, HID_CONNECT_DEFAULT);} static const struct hid_device_id hyperx_devices[] = {	{ HID_USB_DEVICE(USB_VENDOR_ID_HP,			 USB_PRODUCT_ID_HP_HYPERX_QUADCAST_2) },	{ }};MODULE_DEVICE_TABLE(hid, hyperx_devices); static struct hid_driver hyperx_driver = {	.name			= "hyperx",	.id_table		= hyperx_devices,	.probe			= hyperx_probe,	.input_configured	= hyperx_input_configured,	.raw_event		= hyperx_raw_event,};module_hid_driver(hyperx_driver); MODULE_DESCRIPTION("HID driver for the HyperX QuadCast 2 microphone");MODULE_AUTHOR("Benjamin Blume <benjaminblume@posteo.de>");MODULE_LICENSE("GPL");