Introduce a driver for the Corsair Void family of headsets, supporting:
 - Battery reporting (power_supply)
 - Sidetone setting support
 - Physical microphone location reporting
 - Headset and receiver firmware version reporting
 - Built-in alert triggering
 - USB wireless_status

Tested with a Void Pro Wireless, Void Elite Wireless and a Void Elite Wired

Signed-off-by: Stuart Hayhurst <stuart.a.hayhurst@gmail.com>
---

Just a couple questions about the sysfs attributes:
 - Should the sysfs documentation use the implementation date (current), or the date it was submitted?
 - Are the attribute names correct? I guessed reasonable names, but if there's a convention I'll correct them
 - For cases where the wireless headset is disconnected, `microphone_up` returns -ENODEV
  - Should it be left like that, or deregister the attributes when the headset disconnects?

v3 -> v4:
 - Added missing <linux/device.h> include
 - Added missing newline, fix indent
 - Use hid_hw_raw_request return code directly for wireless sidetone
 - Use battery status enum for remaining values
 - Use of devm_kasprintf() to create battery string
 - Moved corsair_void_request_status error reporting to callers
 - Simplified corsair_void_request_status
 - Removed battery_struct_size, use sizeof(*battery_data) instead
 - Removed unnecessary curly brackets in send_alert_store

v2 -> v3:
 - Use __free(kfree) helper to free allocations
 - Combined similar condition checks
 - Check power_supply was created successfully before saving it
 - Removed explicit initialisation of return value in corsair_void_probe
 - Use preferred syntax for drvdata's struct allocation size
 - Removed named success exit point from driver probe
 - Removed unused driver probe exit point

v1 -> v2:
 - Added a module author email address
 - Removed unused variable (psy_cfg)
 - Corrected status request buffer size from 12 bytes to 2 bytes
 - Use enums for battery status
 - Use kmalloc instead of kzalloc where applicable
 - Use __le16 type for cpu_to_le16
 - Use DEVICE_ATTR_RO and DEVICE_ATTR_WO to create attributes
 - Simplified corsair_void_set_sidetone_wired
 - Cleaned up patch description

 .../ABI/testing/sysfs-driver-hid-corsair-void |  38 +
 drivers/hid/Kconfig                           |  10 +
 drivers/hid/Makefile                          |   1 +
 drivers/hid/hid-corsair-void.c                | 829 ++++++++++++++++++
 4 files changed, 878 insertions(+)
 create mode 100644 Documentation/ABI/testing/sysfs-driver-hid-corsair-void
 create mode 100644 drivers/hid/hid-corsair-void.c

diff --git a/Documentation/ABI/testing/sysfs-driver-hid-corsair-void b/Documentation/ABI/testing/sysfs-driver-hid-corsair-void
new file mode 100644
index 000000000000..f933ba15dd6d
--- /dev/null
+++ b/Documentation/ABI/testing/sysfs-driver-hid-corsair-void
@@ -0,0 +1,38 @@
+What:		/sys/bus/hid/drivers/hid-corsair-void/<dev>/fw_version_headset
+Date:		January 2024
+KernelVersion:	6.12
+Contact:	Stuart Hayhurst <stuart.a.hayhurst@gmail.com>
+Description:	(R) The firmware version of the headset
+			* Returns -ENODATA if no version was reported
+
+What:		/sys/bus/hid/drivers/hid-corsair-void/<dev>/fw_version_receiver
+Date:		January 2024
+KernelVersion:	6.12
+Contact:	Stuart Hayhurst <stuart.a.hayhurst@gmail.com>
+Description:	(R) The firmware version of the receiver
+
+What:		/sys/bus/hid/drivers/hid-corsair-void/<dev>/microphone_up
+Date:		July 2023
+KernelVersion:	6.12
+Contact:	Stuart Hayhurst <stuart.a.hayhurst@gmail.com>
+Description:	(R) Get the physical position of the microphone
+			* 1 -> Microphone up
+			* 0 -> Microphone down
+
+What:		/sys/bus/hid/drivers/hid-corsair-void/<dev>/send_alert
+Date:		July 2023
+KernelVersion:	6.12
+Contact:	Stuart Hayhurst <stuart.a.hayhurst@gmail.com>
+Description:	(W) Play a built-in notification from the headset (0 / 1)
+
+What:		/sys/bus/hid/drivers/hid-corsair-void/<dev>/set_sidetone
+Date:		December 2023
+KernelVersion:	6.12
+Contact:	Stuart Hayhurst <stuart.a.hayhurst@gmail.com>
+Description:	(W) Set the sidetone volume (0 - sidetone_max)
+
+What:		/sys/bus/hid/drivers/hid-corsair-void/<dev>/sidetone_max
+Date:		July 2024
+KernelVersion:	6.12
+Contact:	Stuart Hayhurst <stuart.a.hayhurst@gmail.com>
+Description:	(R) Report the maximum sidetone volume
diff --git a/drivers/hid/Kconfig b/drivers/hid/Kconfig
index 08446c89eff6..7dcf911f3367 100644
--- a/drivers/hid/Kconfig
+++ b/drivers/hid/Kconfig
@@ -221,6 +221,16 @@ config HID_CORSAIR
 	- Vengeance K90
 	- Scimitar PRO RGB
 
+config HID_CORSAIR_VOID
+	tristate "Corsair Void headsets"
+	depends on USB_HID
+	select POWER_SUPPLY
+	help
+	Support for Corsair Void headsets.
+
+	Supported devices:
+	- Corsair Void headsets
+
 config HID_COUGAR
 	tristate "Cougar devices"
 	help
diff --git a/drivers/hid/Makefile b/drivers/hid/Makefile
index e40f1ddebbb7..037d7e3b6c3e 100644
--- a/drivers/hid/Makefile
+++ b/drivers/hid/Makefile
@@ -39,6 +39,7 @@ obj-$(CONFIG_HID_CHERRY)	+= hid-cherry.o
 obj-$(CONFIG_HID_CHICONY)	+= hid-chicony.o
 obj-$(CONFIG_HID_CMEDIA)	+= hid-cmedia.o
 obj-$(CONFIG_HID_CORSAIR)	+= hid-corsair.o
+obj-$(CONFIG_HID_CORSAIR_VOID)	+= hid-corsair-void.o
 obj-$(CONFIG_HID_COUGAR)	+= hid-cougar.o
 obj-$(CONFIG_HID_CP2112)	+= hid-cp2112.o
 obj-$(CONFIG_HID_CYPRESS)	+= hid-cypress.o
diff --git a/drivers/hid/hid-corsair-void.c b/drivers/hid/hid-corsair-void.c
new file mode 100644
index 000000000000..6ece56b850fc
--- /dev/null
+++ b/drivers/hid/hid-corsair-void.c
@@ -0,0 +1,829 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ *  HID driver for Corsair Void headsets
+ *
+ *  Copyright (C) 2023-2024 Stuart Hayhurst
+ */
+
+/* -------------------------------------------------------------------------- */
+/* Receiver report information: (ID 100)                                      */
+/* -------------------------------------------------------------------------- */
+/*
+ * When queried, the receiver reponds with 5 bytes to describe the battery
+ *   The power button, mute button and moving the mic also trigger this report
+ * This includes power button + mic + connection + battery status and capacity
+ * The information below may not be perfect, it's been gathered through guesses
+ *
+ * 0: REPORT ID
+ *  100 for the battery packet
+ *
+ * 1: POWER BUTTON + (?)
+ *  Largest bit is 1 when power button pressed
+ *
+ * 2: BATTERY CAPACITY + MIC STATUS
+ *  Battery capacity:
+ *    Seems to report ~54 higher than reality when charging
+ *    Capped at 100, charging or not
+ *  Microphone status:
+ *    Largest bit is set to 1 when the mic is physically up
+ *    No bits change when the mic is muted, only when physically moved
+ *    This report is sent every time the mic is moved, no polling required
+ *
+ * 3: CONNECTION STATUS
+ *  16: Wired headset
+ *  38: Initialising
+ *  49: Lost connection
+ *  51: Disconnected, searching
+ *  52: Disconnected, not searching
+ *  177: Normal
+ *
+ * 4: BATTERY STATUS
+ *  0: Disconnected
+ *  1: Normal
+ *  2: Low
+ *  3: Critical - sent during shutdown
+ *  4: Fully charged
+ *  5: Charging
+ */
+/* -------------------------------------------------------------------------- */
+
+/* -------------------------------------------------------------------------- */
+/* Receiver report information: (ID 102)                                      */
+/* -------------------------------------------------------------------------- */
+/*
+ * When queried, the recevier responds with 4 bytes to describe the firmware
+ * The first 2 bytes are for the receiver, the second 2 are the headset
+ * The headset firmware version will be 0 if no headset is connected
+ *
+ * 0: Recevier firmware major version
+ *  Major version of the receiver's firmware
+ *
+ * 1: Recevier firmware minor version
+ *  Minor version of the receiver's firmware
+ *
+ * 2: Headset firmware major version
+ *  Major version of the headset's firmware
+ *
+ * 3: Headset firmware minor version
+ *  Minor version of the headset's firmware
+ */
+/* -------------------------------------------------------------------------- */
+
+#include <linux/bitfield.h>
+#include <linux/bitops.h>
+#include <linux/cleanup.h>
+#include <linux/device.h>
+#include <linux/hid.h>
+#include <linux/module.h>
+#include <linux/mutex.h>
+#include <linux/power_supply.h>
+#include <linux/usb.h>
+#include <linux/workqueue.h>
+#include <asm/byteorder.h>
+
+#include "hid-ids.h"
+
+#define CORSAIR_VOID_DEVICE(id, type)		{ HID_USB_DEVICE(USB_VENDOR_ID_CORSAIR, (id)), \
+						.driver_data = (type) }
+#define CORSAIR_VOID_WIRELESS_DEVICE(id)	CORSAIR_VOID_DEVICE((id), CORSAIR_VOID_WIRELESS)
+#define CORSAIR_VOID_WIRED_DEVICE(id)		CORSAIR_VOID_DEVICE((id), CORSAIR_VOID_WIRED)
+
+#define CORSAIR_VOID_STATUS_REQUEST_ID		0xC9
+#define CORSAIR_VOID_NOTIF_REQUEST_ID		0xCA
+#define CORSAIR_VOID_SIDETONE_REQUEST_ID	0xFF
+#define CORSAIR_VOID_STATUS_REPORT_ID		0x64
+#define CORSAIR_VOID_FIRMWARE_REPORT_ID		0x66
+
+#define CORSAIR_VOID_USB_SIDETONE_REQUEST	0x1
+#define CORSAIR_VOID_USB_SIDETONE_REQUEST_TYPE	0x21
+#define CORSAIR_VOID_USB_SIDETONE_VALUE		0x200
+#define CORSAIR_VOID_USB_SIDETONE_INDEX		0xB00
+
+#define CORSAIR_VOID_MIC_MASK			GENMASK(7, 7)
+#define CORSAIR_VOID_CAPACITY_MASK		GENMASK(6, 0)
+
+#define CORSAIR_VOID_WIRELESS_CONNECTED		177
+
+#define CORSAIR_VOID_SIDETONE_MAX_WIRELESS	55
+#define CORSAIR_VOID_SIDETONE_MAX_WIRED		4096
+
+enum {
+	CORSAIR_VOID_WIRELESS,
+	CORSAIR_VOID_WIRED,
+};
+
+enum {
+	CORSAIR_VOID_BATTERY_NORMAL	= 1,
+	CORSAIR_VOID_BATTERY_LOW	= 2,
+	CORSAIR_VOID_BATTERY_CRITICAL	= 3,
+	CORSAIR_VOID_BATTERY_CHARGED	= 4,
+	CORSAIR_VOID_BATTERY_CHARGING	= 5,
+};
+
+static enum power_supply_property corsair_void_battery_props[] = {
+	POWER_SUPPLY_PROP_STATUS,
+	POWER_SUPPLY_PROP_PRESENT,
+	POWER_SUPPLY_PROP_CAPACITY,
+	POWER_SUPPLY_PROP_CAPACITY_LEVEL,
+	POWER_SUPPLY_PROP_SCOPE,
+	POWER_SUPPLY_PROP_MODEL_NAME,
+	POWER_SUPPLY_PROP_MANUFACTURER,
+};
+
+struct corsair_void_battery_data {
+	int status;
+	bool present;
+	int capacity;
+	int capacity_level;
+};
+
+struct corsair_void_drvdata {
+	struct hid_device *hid_dev;
+	struct device *dev;
+
+	char *name;
+	bool is_wired;
+	unsigned int sidetone_max;
+
+	struct corsair_void_battery_data battery_data;
+	bool mic_up;
+	bool connected;
+	int fw_receiver_major;
+	int fw_receiver_minor;
+	int fw_headset_major;
+	int fw_headset_minor;
+
+	struct power_supply *battery;
+	struct power_supply_desc battery_desc;
+	struct mutex battery_mutex;
+
+	struct delayed_work delayed_status_work;
+	struct delayed_work delayed_firmware_work;
+	struct work_struct battery_remove_work;
+	struct work_struct battery_add_work;
+};
+
+/*
+ * Functions to process receiver data
+*/
+
+static void corsair_void_set_wireless_status(struct corsair_void_drvdata *drvdata)
+{
+	struct usb_interface *usb_if = to_usb_interface(drvdata->dev->parent);
+
+	if (drvdata->is_wired)
+		return;
+
+	usb_set_wireless_status(usb_if, drvdata->connected ?
+					USB_WIRELESS_STATUS_CONNECTED :
+					USB_WIRELESS_STATUS_DISCONNECTED);
+}
+
+static void corsair_void_set_unknown_batt(struct corsair_void_drvdata *drvdata)
+{
+	struct corsair_void_battery_data *battery_data = &drvdata->battery_data;
+
+	battery_data->status = POWER_SUPPLY_STATUS_UNKNOWN;
+	battery_data->present = false;
+	battery_data->capacity = 0;
+	battery_data->capacity_level = POWER_SUPPLY_CAPACITY_LEVEL_UNKNOWN;
+}
+
+/* Reset data that may change between wireless connections */
+static void corsair_void_set_unknown_wireless_data(struct corsair_void_drvdata *drvdata)
+{
+	/* Only 0 out headset, receiver is always known if relevant */
+	drvdata->fw_headset_major = 0;
+	drvdata->fw_headset_minor = 0;
+
+	drvdata->connected = false;
+	drvdata->mic_up = false;
+
+	corsair_void_set_wireless_status(drvdata);
+}
+
+static void corsair_void_process_receiver(struct corsair_void_drvdata *drvdata,
+					  int raw_battery_capacity,
+					  int raw_connection_status,
+					  int raw_battery_status)
+{
+	struct corsair_void_battery_data *battery_data = &drvdata->battery_data;
+	struct corsair_void_battery_data orig_battery_data;
+
+	/* Save initial battery data, to compare later */
+	orig_battery_data = *battery_data;
+
+	/* Headset not connected, or it's wired */
+	if (raw_connection_status != CORSAIR_VOID_WIRELESS_CONNECTED)
+		goto unknown_battery;
+
+	/* Battery information unavailable */
+	if (raw_battery_status == 0)
+		goto unknown_battery;
+
+	/* Battery must be connected then */
+	battery_data->present = true;
+	battery_data->capacity_level = POWER_SUPPLY_CAPACITY_LEVEL_NORMAL;
+
+	/* Set battery status */
+	switch (raw_battery_status) {
+	case CORSAIR_VOID_BATTERY_NORMAL:
+	case CORSAIR_VOID_BATTERY_LOW:
+	case CORSAIR_VOID_BATTERY_CRITICAL:
+		battery_data->status = POWER_SUPPLY_STATUS_DISCHARGING;
+		if (raw_battery_status == CORSAIR_VOID_BATTERY_LOW)
+			battery_data->capacity_level = POWER_SUPPLY_CAPACITY_LEVEL_LOW;
+		else if (raw_battery_status == CORSAIR_VOID_BATTERY_CRITICAL)
+			battery_data->capacity_level = POWER_SUPPLY_CAPACITY_LEVEL_CRITICAL;
+
+		break;
+	case CORSAIR_VOID_BATTERY_CHARGED:
+		battery_data->status = POWER_SUPPLY_STATUS_FULL;
+		break;
+	case CORSAIR_VOID_BATTERY_CHARGING:
+		battery_data->status = POWER_SUPPLY_STATUS_CHARGING;
+		break;
+	default:
+		hid_warn(drvdata->hid_dev, "unknown battery status '%d'",
+			 raw_battery_status);
+		goto unknown_battery;
+		break;
+	}
+
+	battery_data->capacity = raw_battery_capacity;
+	corsair_void_set_wireless_status(drvdata);
+
+	goto success;
+unknown_battery:
+	corsair_void_set_unknown_batt(drvdata);
+success:
+
+	/* Inform power supply if battery values changed */
+	if (memcmp(&orig_battery_data, battery_data, sizeof(*battery_data))) {
+		scoped_guard(mutex, &drvdata->battery_mutex) {
+			if (drvdata->battery) {
+				power_supply_changed(drvdata->battery);
+			}
+		}
+	}
+}
+
+/*
+ * Functions to report stored data
+*/
+
+static int corsair_void_battery_get_property(struct power_supply *psy,
+					     enum power_supply_property prop,
+					     union power_supply_propval *val)
+{
+	struct corsair_void_drvdata *drvdata = power_supply_get_drvdata(psy);
+
+	switch (prop) {
+		case POWER_SUPPLY_PROP_SCOPE:
+			val->intval = POWER_SUPPLY_SCOPE_DEVICE;
+			break;
+		case POWER_SUPPLY_PROP_MODEL_NAME:
+			if (!strncmp(drvdata->hid_dev->name, "Corsair ", 8))
+				val->strval = drvdata->hid_dev->name + 8;
+			else
+				val->strval = drvdata->hid_dev->name;
+			break;
+		case POWER_SUPPLY_PROP_MANUFACTURER:
+			val->strval = "Corsair";
+			break;
+		case POWER_SUPPLY_PROP_STATUS:
+			val->intval = drvdata->battery_data.status;
+			break;
+		case POWER_SUPPLY_PROP_PRESENT:
+			val->intval = drvdata->battery_data.present;
+			break;
+		case POWER_SUPPLY_PROP_CAPACITY:
+			val->intval = drvdata->battery_data.capacity;
+			break;
+		case POWER_SUPPLY_PROP_CAPACITY_LEVEL:
+			val->intval = drvdata->battery_data.capacity_level;
+			break;
+		default:
+			return -EINVAL;
+	}
+
+	return 0;
+}
+
+static ssize_t microphone_up_show(struct device *dev,
+				  struct device_attribute *attr, char *buf)
+{
+	struct corsair_void_drvdata *drvdata = dev_get_drvdata(dev);
+
+	if (!drvdata->connected)
+		return -ENODEV;
+
+	return sysfs_emit(buf, "%d\n", drvdata->mic_up);
+}
+
+static ssize_t fw_version_receiver_show(struct device *dev,
+					struct device_attribute *attr,
+					char *buf)
+{
+	struct corsair_void_drvdata *drvdata = dev_get_drvdata(dev);
+
+	if (drvdata->fw_receiver_major == 0 && drvdata->fw_receiver_minor == 0)
+		return -ENODATA;
+
+	return sysfs_emit(buf, "%d.%02d\n", drvdata->fw_receiver_major,
+			  drvdata->fw_receiver_minor);
+}
+
+
+static ssize_t fw_version_headset_show(struct device *dev,
+				       struct device_attribute *attr,
+				       char *buf)
+{
+	struct corsair_void_drvdata *drvdata = dev_get_drvdata(dev);
+
+	if (drvdata->fw_headset_major == 0 && drvdata->fw_headset_minor == 0)
+		return -ENODATA;
+
+	return sysfs_emit(buf, "%d.%02d\n", drvdata->fw_headset_major,
+			  drvdata->fw_headset_minor);
+}
+
+static ssize_t sidetone_max_show(struct device *dev,
+				 struct device_attribute *attr,
+				 char *buf)
+{
+	struct corsair_void_drvdata *drvdata = dev_get_drvdata(dev);
+
+	return sysfs_emit(buf, "%d\n", drvdata->sidetone_max);
+}
+
+/*
+ * Functions to send data to headset
+*/
+
+static ssize_t send_alert_store(struct device *dev,
+				struct device_attribute *attr,
+				const char *buf, size_t count)
+{
+	struct corsair_void_drvdata *drvdata = dev_get_drvdata(dev);
+	struct hid_device *hid_dev = drvdata->hid_dev;
+	unsigned char alert_id;
+	unsigned char *send_buf __free(kfree) = NULL;
+	int ret;
+
+	if (!drvdata->connected || drvdata->is_wired)
+		return -ENODEV;
+
+	/* Only accept 0 or 1 for alert ID */
+	if (kstrtou8(buf, 10, &alert_id) || alert_id >= 2)
+		return -EINVAL;
+
+	send_buf = kmalloc(3, GFP_KERNEL);
+	if (!send_buf)
+		return -ENOMEM;
+
+	/* Packet format to send alert with ID alert_id */
+	send_buf[0] = CORSAIR_VOID_NOTIF_REQUEST_ID;
+	send_buf[1] = 0x02;
+	send_buf[2] = alert_id;
+
+	ret = hid_hw_raw_request(hid_dev, CORSAIR_VOID_NOTIF_REQUEST_ID,
+				 send_buf, 3, HID_OUTPUT_REPORT,
+				 HID_REQ_SET_REPORT);
+	if (ret < 0)
+		hid_warn(hid_dev, "failed to send alert request (reason: %d)",
+			 ret);
+	else
+		ret = count;
+
+	return ret;
+}
+
+static int corsair_void_set_sidetone_wired(struct device *dev, const char *buf,
+					   unsigned int sidetone)
+{
+	struct usb_interface *usb_if = to_usb_interface(dev->parent);
+	struct usb_device *usb_dev = interface_to_usbdev(usb_if);
+
+	/* Packet format to set sidetone for wired headsets */
+	__le16 sidetone_le = cpu_to_le16(sidetone);
+
+	return usb_control_msg_send(usb_dev, 0,
+				   CORSAIR_VOID_USB_SIDETONE_REQUEST,
+				   CORSAIR_VOID_USB_SIDETONE_REQUEST_TYPE,
+				   CORSAIR_VOID_USB_SIDETONE_VALUE,
+				   CORSAIR_VOID_USB_SIDETONE_INDEX,
+				   &sidetone_le, 2, USB_CTRL_SET_TIMEOUT,
+				   GFP_KERNEL);
+}
+
+static int corsair_void_set_sidetone_wireless(struct device *dev,
+					      const char *buf,
+					      unsigned char sidetone)
+{
+	struct corsair_void_drvdata *drvdata = dev_get_drvdata(dev);
+	struct hid_device *hid_dev = drvdata->hid_dev;
+	unsigned char *send_buf __free(kfree) = NULL;
+
+	send_buf = kmalloc(12, GFP_KERNEL);
+	if (!send_buf)
+		return -ENOMEM;
+
+	/* Packet format to set sidetone for wireless headsets */
+	send_buf[0] = CORSAIR_VOID_SIDETONE_REQUEST_ID;
+	send_buf[1] = 0x0B;
+	send_buf[2] = 0x00;
+	send_buf[3] = 0xFF;
+	send_buf[4] = 0x04;
+	send_buf[5] = 0x0E;
+	send_buf[6] = 0xFF;
+	send_buf[7] = 0x05;
+	send_buf[8] = 0x01;
+	send_buf[9] = 0x04;
+	send_buf[10] = 0x00;
+	send_buf[11] = sidetone + 200;
+
+	return hid_hw_raw_request(hid_dev, CORSAIR_VOID_SIDETONE_REQUEST_ID,
+				  send_buf, 12, HID_FEATURE_REPORT,
+				  HID_REQ_SET_REPORT);
+}
+
+static ssize_t set_sidetone_store(struct device *dev,
+				  struct device_attribute *attr,
+				  const char *buf, size_t count)
+{
+	struct corsair_void_drvdata *drvdata = dev_get_drvdata(dev);
+	struct hid_device *hid_dev = drvdata->hid_dev;
+	unsigned int sidetone;
+	int ret;
+
+	if (!drvdata->connected)
+		return -ENODEV;
+
+	/* sidetone must be between 0 and drvdata->sidetone_max inclusive */
+	if (kstrtouint(buf, 10, &sidetone) || sidetone > drvdata->sidetone_max)
+		return -EINVAL;
+
+	if (drvdata->is_wired)
+		ret = corsair_void_set_sidetone_wired(dev, buf, sidetone);
+	else
+		ret = corsair_void_set_sidetone_wireless(dev, buf, sidetone);
+
+	if (ret < 0)
+		hid_warn(hid_dev, "failed to send sidetone (reason: %d)", ret);
+	else
+		ret = count;
+
+	return ret;
+}
+
+static int corsair_void_request_status(struct hid_device *hid_dev, int id)
+{
+	unsigned char *send_buf __free(kfree) = NULL;
+
+	send_buf = kmalloc(2, GFP_KERNEL);
+	if (!send_buf)
+		return -ENOMEM;
+
+	/* Packet format to request data item (status / firmware) refresh */
+	send_buf[0] = CORSAIR_VOID_STATUS_REQUEST_ID;
+	send_buf[1] = id;
+
+	/* Send request for data refresh */
+	return hid_hw_raw_request(hid_dev, CORSAIR_VOID_STATUS_REQUEST_ID,
+				  send_buf, 2, HID_OUTPUT_REPORT,
+				  HID_REQ_SET_REPORT);
+}
+
+/*
+ * Headset connect / disconnect handlers and work handlers
+*/
+
+static void corsair_void_status_work_handler(struct work_struct *work)
+{
+	struct corsair_void_drvdata *drvdata;
+	struct delayed_work *delayed_work;
+	int battery_ret;
+
+	delayed_work = container_of(work, struct delayed_work, work);
+	drvdata = container_of(delayed_work, struct corsair_void_drvdata,
+			       delayed_status_work);
+
+	battery_ret = corsair_void_request_status(drvdata->hid_dev,
+						  CORSAIR_VOID_STATUS_REPORT_ID);
+	if (battery_ret < 0) {
+		hid_warn(drvdata->hid_dev,
+			 "failed to request battery (reason: %d)", battery_ret);
+	}
+}
+
+static void corsair_void_firmware_work_handler(struct work_struct *work)
+{
+	struct corsair_void_drvdata *drvdata;
+	struct delayed_work *delayed_work;
+	int firmware_ret;
+
+	delayed_work = container_of(work, struct delayed_work, work);
+	drvdata = container_of(delayed_work, struct corsair_void_drvdata,
+			       delayed_firmware_work);
+
+	firmware_ret = corsair_void_request_status(drvdata->hid_dev,
+						   CORSAIR_VOID_FIRMWARE_REPORT_ID);
+	if (firmware_ret < 0) {
+		hid_warn(drvdata->hid_dev,
+			 "failed to request firmware (reason: %d)", firmware_ret);
+	}
+
+}
+
+static void corsair_void_battery_remove_work_handler(struct work_struct *work)
+{
+	struct corsair_void_drvdata *drvdata;
+
+	drvdata = container_of(work, struct corsair_void_drvdata,
+			       battery_remove_work);
+	scoped_guard(mutex, &drvdata->battery_mutex) {
+		if (drvdata->battery) {
+			power_supply_unregister(drvdata->battery);
+			drvdata->battery = NULL;
+		}
+	}
+}
+
+static void corsair_void_battery_add_work_handler(struct work_struct *work)
+{
+	struct corsair_void_drvdata *drvdata;
+	struct power_supply_config psy_cfg;
+	struct power_supply *new_supply;
+
+	drvdata = container_of(work, struct corsair_void_drvdata,
+			       battery_add_work);
+	guard(mutex)(&drvdata->battery_mutex);
+	if (drvdata->battery)
+		return;
+
+	psy_cfg.drv_data = drvdata;
+	new_supply = power_supply_register(drvdata->dev,
+					   &drvdata->battery_desc,
+					   &psy_cfg);
+
+	if (IS_ERR(new_supply)) {
+		hid_err(drvdata->hid_dev,
+			"failed to register battery '%s' (reason: %ld)\n",
+			drvdata->battery_desc.name,
+			PTR_ERR(new_supply));
+		return;
+	}
+
+	if (power_supply_powers(new_supply, drvdata->dev)) {
+		power_supply_unregister(new_supply);
+		return;
+	}
+
+	drvdata->battery = new_supply;
+}
+
+static void corsair_void_headset_connected(struct corsair_void_drvdata *drvdata)
+{
+	schedule_work(&drvdata->battery_add_work);
+	schedule_delayed_work(&drvdata->delayed_firmware_work,
+			      msecs_to_jiffies(100));
+}
+
+static void corsair_void_headset_disconnected(struct corsair_void_drvdata *drvdata)
+{
+	schedule_work(&drvdata->battery_remove_work);
+
+	corsair_void_set_unknown_wireless_data(drvdata);
+	corsair_void_set_unknown_batt(drvdata);
+}
+
+/*
+ * Driver setup, probing and HID event handling
+*/
+
+static DEVICE_ATTR_RO(fw_version_receiver);
+static DEVICE_ATTR_RO(fw_version_headset);
+static DEVICE_ATTR_RO(microphone_up);
+static DEVICE_ATTR_RO(sidetone_max);
+
+static DEVICE_ATTR_WO(send_alert);
+static DEVICE_ATTR_WO(set_sidetone);
+
+static struct attribute *corsair_void_attrs[] = {
+	&dev_attr_fw_version_receiver.attr,
+	&dev_attr_fw_version_headset.attr,
+	&dev_attr_microphone_up.attr,
+	&dev_attr_send_alert.attr,
+	&dev_attr_set_sidetone.attr,
+	&dev_attr_sidetone_max.attr,
+	NULL,
+};
+
+static const struct attribute_group corsair_void_attr_group = {
+	.attrs = corsair_void_attrs,
+};
+
+static int corsair_void_probe(struct hid_device *hid_dev,
+			      const struct hid_device_id *hid_id)
+{
+	int ret;
+	struct corsair_void_drvdata *drvdata;
+	char *name;
+
+	if (!hid_is_usb(hid_dev))
+		return -EINVAL;
+
+	drvdata = devm_kzalloc(&hid_dev->dev, sizeof(*drvdata),
+			       GFP_KERNEL);
+	if (!drvdata)
+		return -ENOMEM;
+
+	hid_set_drvdata(hid_dev, drvdata);
+	dev_set_drvdata(&hid_dev->dev, drvdata);
+
+	drvdata->dev = &hid_dev->dev;
+	drvdata->hid_dev = hid_dev;
+	drvdata->is_wired = hid_id->driver_data == CORSAIR_VOID_WIRED;
+
+	drvdata->sidetone_max = CORSAIR_VOID_SIDETONE_MAX_WIRELESS;
+	if (drvdata->is_wired)
+		drvdata->sidetone_max = CORSAIR_VOID_SIDETONE_MAX_WIRED;
+
+	/* Set initial values for no wireless headset attached */
+	/* If a headset is attached, it'll be prompted later */
+	corsair_void_set_unknown_wireless_data(drvdata);
+	corsair_void_set_unknown_batt(drvdata);
+
+	/* Receiver version won't be reset after init */
+	/* Headset version already set via set_unknown_wireless_data */
+	drvdata->fw_receiver_major = 0;
+	drvdata->fw_receiver_minor = 0;
+
+	ret = hid_parse(hid_dev);
+	if (ret) {
+		hid_err(hid_dev, "parse failed (reason: %d)\n", ret);
+		return ret;
+	}
+
+	name = devm_kasprintf(drvdata->dev, GFP_KERNEL,
+			      "corsair-void-%d-battery", hid_dev->id);
+	if (!name)
+		return -ENOMEM;
+
+	drvdata->battery_desc.name = name;
+	drvdata->battery_desc.type = POWER_SUPPLY_TYPE_BATTERY;
+	drvdata->battery_desc.properties = corsair_void_battery_props;
+	drvdata->battery_desc.num_properties = ARRAY_SIZE(corsair_void_battery_props);
+	drvdata->battery_desc.get_property = corsair_void_battery_get_property;
+
+	drvdata->battery = NULL;
+	INIT_WORK(&drvdata->battery_remove_work,
+		  corsair_void_battery_remove_work_handler);
+	INIT_WORK(&drvdata->battery_add_work,
+		  corsair_void_battery_add_work_handler);
+	ret = devm_mutex_init(drvdata->dev, &drvdata->battery_mutex);
+	if (ret)
+		return ret;
+
+	ret = sysfs_create_group(&hid_dev->dev.kobj, &corsair_void_attr_group);
+	if (ret)
+		return ret;
+
+	/* Any failures after here will need to call hid_hw_stop */
+	ret = hid_hw_start(hid_dev, HID_CONNECT_DEFAULT);
+	if (ret) {
+		hid_err(hid_dev, "hid_hw_start failed (reason: %d)\n", ret);
+		goto failed_after_sysfs;
+	}
+
+	/* Refresh battery data, in case wireless headset is already connected */
+	INIT_DELAYED_WORK(&drvdata->delayed_status_work,
+			  corsair_void_status_work_handler);
+	schedule_delayed_work(&drvdata->delayed_status_work,
+			      msecs_to_jiffies(100));
+
+	/* Refresh firmware versions */
+	INIT_DELAYED_WORK(&drvdata->delayed_firmware_work,
+			  corsair_void_firmware_work_handler);
+	schedule_delayed_work(&drvdata->delayed_firmware_work,
+			      msecs_to_jiffies(100));
+
+	return 0;
+
+failed_after_sysfs:
+	sysfs_remove_group(&hid_dev->dev.kobj, &corsair_void_attr_group);
+	return ret;
+}
+
+static void corsair_void_remove(struct hid_device *hid_dev)
+{
+	struct corsair_void_drvdata *drvdata = hid_get_drvdata(hid_dev);
+
+	hid_hw_stop(hid_dev);
+	cancel_work_sync(&drvdata->battery_remove_work);
+	cancel_work_sync(&drvdata->battery_add_work);
+	if (drvdata->battery)
+		power_supply_unregister(drvdata->battery);
+
+	cancel_delayed_work_sync(&drvdata->delayed_firmware_work);
+	sysfs_remove_group(&hid_dev->dev.kobj, &corsair_void_attr_group);
+}
+
+static int corsair_void_raw_event(struct hid_device *hid_dev,
+				  struct hid_report *hid_report,
+				  u8 *data, int size)
+{
+	struct corsair_void_drvdata *drvdata = hid_get_drvdata(hid_dev);
+	bool was_connected = drvdata->connected;
+
+	/* Description of packets are documented at the top of this file */
+	if (hid_report->id == CORSAIR_VOID_STATUS_REPORT_ID) {
+		drvdata->mic_up = FIELD_GET(CORSAIR_VOID_MIC_MASK, data[2]);
+		drvdata->connected = (data[3] == CORSAIR_VOID_WIRELESS_CONNECTED) ||
+				     drvdata->is_wired;
+
+		corsair_void_process_receiver(drvdata,
+					      FIELD_GET(CORSAIR_VOID_CAPACITY_MASK, data[2]),
+					      data[3], data[4]);
+	} else if (hid_report->id == CORSAIR_VOID_FIRMWARE_REPORT_ID) {
+		drvdata->fw_receiver_major = data[1];
+		drvdata->fw_receiver_minor = data[2];
+		drvdata->fw_headset_major = data[3];
+		drvdata->fw_headset_minor = data[4];
+	}
+
+	/* Handle wireless headset connect / disconnect */
+	if ((was_connected != drvdata->connected) && !drvdata->is_wired) {
+		if (drvdata->connected)
+			corsair_void_headset_connected(drvdata);
+		else
+			corsair_void_headset_disconnected(drvdata);
+	}
+
+	return 0;
+}
+
+static const struct hid_device_id corsair_void_devices[] = {
+	/* Corsair Void Wireless */
+	CORSAIR_VOID_WIRELESS_DEVICE(0x0a0c),
+	CORSAIR_VOID_WIRELESS_DEVICE(0x0a2b),
+	CORSAIR_VOID_WIRELESS_DEVICE(0x1b23),
+	CORSAIR_VOID_WIRELESS_DEVICE(0x1b25),
+	CORSAIR_VOID_WIRELESS_DEVICE(0x1b27),
+
+	/* Corsair Void USB */
+	CORSAIR_VOID_WIRED_DEVICE(0x0a0f),
+	CORSAIR_VOID_WIRED_DEVICE(0x1b1c),
+	CORSAIR_VOID_WIRED_DEVICE(0x1b29),
+	CORSAIR_VOID_WIRED_DEVICE(0x1b2a),
+
+	/* Corsair Void Surround */
+	CORSAIR_VOID_WIRED_DEVICE(0x0a30),
+	CORSAIR_VOID_WIRED_DEVICE(0x0a31),
+
+	/* Corsair Void Pro Wireless */
+	CORSAIR_VOID_WIRELESS_DEVICE(0x0a14),
+	CORSAIR_VOID_WIRELESS_DEVICE(0x0a16),
+	CORSAIR_VOID_WIRELESS_DEVICE(0x0a1a),
+
+	/* Corsair Void Pro USB */
+	CORSAIR_VOID_WIRED_DEVICE(0x0a17),
+	CORSAIR_VOID_WIRED_DEVICE(0x0a1d),
+
+	/* Corsair Void Pro Surround */
+	CORSAIR_VOID_WIRED_DEVICE(0x0a18),
+	CORSAIR_VOID_WIRED_DEVICE(0x0a1e),
+	CORSAIR_VOID_WIRED_DEVICE(0x0a1f),
+
+	/* Corsair Void Elite Wireless */
+	CORSAIR_VOID_WIRELESS_DEVICE(0x0a51),
+	CORSAIR_VOID_WIRELESS_DEVICE(0x0a55),
+	CORSAIR_VOID_WIRELESS_DEVICE(0x0a75),
+
+	/* Corsair Void Elite USB */
+	CORSAIR_VOID_WIRED_DEVICE(0x0a52),
+	CORSAIR_VOID_WIRED_DEVICE(0x0a56),
+
+	/* Corsair Void Elite Surround */
+	CORSAIR_VOID_WIRED_DEVICE(0x0a53),
+	CORSAIR_VOID_WIRED_DEVICE(0x0a57),
+
+	{}
+};
+
+MODULE_DEVICE_TABLE(hid, corsair_void_devices);
+
+static struct hid_driver corsair_void_driver = {
+	.name = "hid-corsair-void",
+	.id_table = corsair_void_devices,
+	.probe = corsair_void_probe,
+	.remove = corsair_void_remove,
+	.raw_event = corsair_void_raw_event,
+};
+
+module_hid_driver(corsair_void_driver);
+
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Stuart Hayhurst <stuart.a.hayhurst@gmail.com>");
+MODULE_DESCRIPTION("HID driver for Corsair Void headsets");
-- 
2.45.2

On Mon, 9 Sep 2024, Stuart Hayhurst wrote:

> Introduce a driver for the Corsair Void family of headsets, supporting:
>  - Battery reporting (power_supply)
>  - Sidetone setting support
>  - Physical microphone location reporting
>  - Headset and receiver firmware version reporting
>  - Built-in alert triggering
>  - USB wireless_status
> 
> Tested with a Void Pro Wireless, Void Elite Wireless and a Void Elite Wired
> 
> Signed-off-by: Stuart Hayhurst <stuart.a.hayhurst@gmail.com>

Thanks a lot for working on this! I have one small nit:

[ ... snip ... ]
> +config HID_CORSAIR_VOID
> +	tristate "Corsair Void headsets"
> +	depends on USB_HID
> +	select POWER_SUPPLY
> +	help
> +	Support for Corsair Void headsets.
> +
> +	Supported devices:
> +	- Corsair Void headsets
> +

As we alreay have general CONFIG_HID_CORSAIR, I think it'd make sense for 
this driver to be encapsulated under this config option as well (it'd also 
follow the general practice of HID subsystem, that the drivers are divided 
per vendor) -- i.e. link hid-corsair-void into the final hid-corsair.ko 
whenever CONFIG_HID_CORSAIR is selected.

Would you be willing to make that small change, and resubmit for final 
merge?

Thanks,

-- 
Jiri Kosina
SUSE Labs

> As we alreay have general CONFIG_HID_CORSAIR, I think it'd make sense for
> this driver to be encapsulated under this config option as well (it'd also
> follow the general practice of HID subsystem, that the drivers are divided
> per vendor) -- i.e. link hid-corsair-void into the final hid-corsair.ko
> whenever CONFIG_HID_CORSAIR is selected.
>
> Would you be willing to make that small change, and resubmit for final
> merge?

Sure that makes sense, but I'm not sure how to do that exactly. Is
there an example anywhere?

Thanks,
Stuart

On Tue, 8 Oct 2024, Stuart wrote:

> > As we alreay have general CONFIG_HID_CORSAIR, I think it'd make sense for
> > this driver to be encapsulated under this config option as well (it'd also
> > follow the general practice of HID subsystem, that the drivers are divided
> > per vendor) -- i.e. link hid-corsair-void into the final hid-corsair.ko
> > whenever CONFIG_HID_CORSAIR is selected.
> >
> > Would you be willing to make that small change, and resubmit for final
> > merge?
> 
> Sure that makes sense, but I'm not sure how to do that exactly. Is
> there an example anywhere?

Just do something like

	obj-$(CONFIG_HID_CORSAIR)  += hid-corsair.o hid-corsair-void.o

in the Makefile. There are a few HID drivers there doing exactly that. 
hid-roccat is probably the biggest user of this :)

Thanks,

-- 
Jiri Kosina
SUSE Labs