HID: corsair: Add Corsair Vengeance K90 driver

This patch implements a HID driver for the Corsair Vengeance K90 keyboard.

It fixes the behaviour of the keys using incorrect HID usage codes and exposes
the macro playback mode and current profile to the user space through sysfs
attributes. It also adds two LED class devices controlling the "record" LED and
the backlight.

Signed-off-by: Clément Vuchener <[e-mail]>
Signed-off-by: Jiri Kosina <[e-mail]>

Documentation/ABI/testing/sysfs-driver-hid-corsair

···
+What:		/sys/bus/drivers/corsair/<dev>/macro_mode
+Date:		August 2015
+KernelVersion:	4.2
+Contact:	Clement Vuchener <[e-mail]>
+Description:	Get/set the current playback mode. "SW" for software mode
+		where G-keys triggers their regular key codes. "HW" for
+		hardware playback mode where the G-keys play their macro
+		from the on-board memory.
+
+
+What:		/sys/bus/drivers/corsair/<dev>/current_profile
+Date:		August 2015
+KernelVersion:	4.2
+Contact:	Clement Vuchener <[e-mail]>
+Description:	Get/set the current selected profile. Values are from 1 to 3.

drivers/hid/Kconfig

···
 	---help---
 	Support for Chicony Tactical pad.
 
+config HID_CORSAIR
+	tristate "Corsair devices"
+	depends on HID && USB && LEDS_CLASS
+	---help---
+	Support for Corsair devices that are not fully compliant with the
+	HID standard.
+
+	Supported devices:
+	- Vengeance K90
+
 config HID_PRODIKEYS
 	tristate "Prodikeys PC-MIDI Keyboard support"
 	depends on HID && SND

drivers/hid/Makefile

···
 obj-$(CONFIG_HID_BETOP_FF)	+= hid-betopff.o
 obj-$(CONFIG_HID_CHERRY)	+= hid-cherry.o
 obj-$(CONFIG_HID_CHICONY)	+= hid-chicony.o
+obj-$(CONFIG_HID_CORSAIR)	+= hid-corsair.o
 obj-$(CONFIG_HID_CP2112)	+= hid-cp2112.o
 obj-$(CONFIG_HID_CYPRESS)	+= hid-cypress.o
 obj-$(CONFIG_HID_DRAGONRISE)	+= hid-dr.o

drivers/hid/hid-core.c

···
 	{ HID_USB_DEVICE(USB_VENDOR_ID_CHICONY, USB_DEVICE_ID_CHICONY_WIRELESS2) },
 	{ HID_USB_DEVICE(USB_VENDOR_ID_CHICONY, USB_DEVICE_ID_CHICONY_AK1D) },
 	{ HID_USB_DEVICE(USB_VENDOR_ID_CHICONY, USB_DEVICE_ID_CHICONY_ACER_SWITCH12) },
+	{ HID_USB_DEVICE(USB_VENDOR_ID_CORSAIR, USB_DEVICE_ID_CORSAIR_K90) },
 	{ HID_USB_DEVICE(USB_VENDOR_ID_CREATIVELABS, USB_DEVICE_ID_PRODIKEYS_PCMIDI) },
 	{ HID_USB_DEVICE(USB_VENDOR_ID_CYGNAL, USB_DEVICE_ID_CYGNAL_CP2112) },
 	{ HID_USB_DEVICE(USB_VENDOR_ID_CYPRESS, USB_DEVICE_ID_CYPRESS_BARCODE_1) },

drivers/hid/hid-corsair.c

···
+/*
+ * HID driver for Corsair devices
+ *
+ * Supported devices:
+ *  - Vengeance K90 Keyboard
+ *
+ * Copyright (c) 2015 Clement Vuchener
+ */
+
+/*
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License as published by the Free
+ * Software Foundation; either version 2 of the License, or (at your option)
+ * any later version.
+ */
+
+#include <linux/hid.h>
+#include <linux/module.h>
+#include <linux/usb.h>
+#include <linux/leds.h>
+
+#include "hid-ids.h"
+
+#define CORSAIR_USE_K90_MACRO	(1<<0)
+#define CORSAIR_USE_K90_BACKLIGHT	(1<<1)
+
+struct k90_led {
+	struct led_classdev cdev;
+	int brightness;
+	struct work_struct work;
+	int removed;
+};
+
+struct k90_drvdata {
+	struct k90_led record_led;
+};
+
+struct corsair_drvdata {
+	unsigned long quirks;
+	struct k90_drvdata *k90;
+	struct k90_led *backlight;
+};
+
+#define K90_GKEY_COUNT	18
+
+static int corsair_usage_to_gkey(unsigned int usage)
+{
+	/* G1 (0xd0) to G16 (0xdf) */
+	if (usage >= 0xd0 && usage <= 0xdf)
+		return usage - 0xd0 + 1;
+	/* G17 (0xe8) to G18 (0xe9) */
+	if (usage >= 0xe8 && usage <= 0xe9)
+		return usage - 0xe8 + 17;
+	return 0;
+}
+
+static unsigned short corsair_gkey_map[K90_GKEY_COUNT] = {
+	BTN_TRIGGER_HAPPY1,
+	BTN_TRIGGER_HAPPY2,
+	BTN_TRIGGER_HAPPY3,
+	BTN_TRIGGER_HAPPY4,
+	BTN_TRIGGER_HAPPY5,
+	BTN_TRIGGER_HAPPY6,
+	BTN_TRIGGER_HAPPY7,
+	BTN_TRIGGER_HAPPY8,
+	BTN_TRIGGER_HAPPY9,
+	BTN_TRIGGER_HAPPY10,
+	BTN_TRIGGER_HAPPY11,
+	BTN_TRIGGER_HAPPY12,
+	BTN_TRIGGER_HAPPY13,
+	BTN_TRIGGER_HAPPY14,
+	BTN_TRIGGER_HAPPY15,
+	BTN_TRIGGER_HAPPY16,
+	BTN_TRIGGER_HAPPY17,
+	BTN_TRIGGER_HAPPY18,
+};
+
+module_param_array_named(gkey_codes, corsair_gkey_map, ushort, NULL, S_IRUGO);
+MODULE_PARM_DESC(gkey_codes, "Key codes for the G-keys");
+
+static unsigned short corsair_record_keycodes[2] = {
+	BTN_TRIGGER_HAPPY19,
+	BTN_TRIGGER_HAPPY20
+};
+
+module_param_array_named(recordkey_codes, corsair_record_keycodes, ushort,
+			 NULL, S_IRUGO);
+MODULE_PARM_DESC(recordkey_codes, "Key codes for the MR (start and stop record) button");
+
+static unsigned short corsair_profile_keycodes[3] = {
+	BTN_TRIGGER_HAPPY21,
+	BTN_TRIGGER_HAPPY22,
+	BTN_TRIGGER_HAPPY23
+};
+
+module_param_array_named(profilekey_codes, corsair_profile_keycodes, ushort,
+			 NULL, S_IRUGO);
+MODULE_PARM_DESC(profilekey_codes, "Key codes for the profile buttons");
+
+#define CORSAIR_USAGE_SPECIAL_MIN 0xf0
+#define CORSAIR_USAGE_SPECIAL_MAX 0xff
+
+#define CORSAIR_USAGE_MACRO_RECORD_START 0xf6
+#define CORSAIR_USAGE_MACRO_RECORD_STOP 0xf7
+
+#define CORSAIR_USAGE_PROFILE 0xf1
+#define CORSAIR_USAGE_M1 0xf1
+#define CORSAIR_USAGE_M2 0xf2
+#define CORSAIR_USAGE_M3 0xf3
+#define CORSAIR_USAGE_PROFILE_MAX 0xf3
+
+#define CORSAIR_USAGE_META_OFF 0xf4
+#define CORSAIR_USAGE_META_ON  0xf5
+
+#define CORSAIR_USAGE_LIGHT 0xfa
+#define CORSAIR_USAGE_LIGHT_OFF 0xfa
+#define CORSAIR_USAGE_LIGHT_DIM 0xfb
+#define CORSAIR_USAGE_LIGHT_MEDIUM 0xfc
+#define CORSAIR_USAGE_LIGHT_BRIGHT 0xfd
+#define CORSAIR_USAGE_LIGHT_MAX 0xfd
+
+/* USB control protocol */
+
+#define K90_REQUEST_BRIGHTNESS 49
+#define K90_REQUEST_MACRO_MODE 2
+#define K90_REQUEST_STATUS 4
+#define K90_REQUEST_GET_MODE 5
+#define K90_REQUEST_PROFILE 20
+
+#define K90_MACRO_MODE_SW 0x0030
+#define K90_MACRO_MODE_HW 0x0001
+
+#define K90_MACRO_LED_ON  0x0020
+#define K90_MACRO_LED_OFF 0x0040
+
+/*
+ * LED class devices
+ */
+
+#define K90_BACKLIGHT_LED_SUFFIX "::backlight"
+#define K90_RECORD_LED_SUFFIX "::record"
+
+static enum led_brightness k90_backlight_get(struct led_classdev *led_cdev)
+{
+	int ret;
+	struct k90_led *led = container_of(led_cdev, struct k90_led, cdev);
+	struct device *dev = led->cdev.dev->parent;
+	struct usb_interface *usbif = to_usb_interface(dev->parent);
+	struct usb_device *usbdev = interface_to_usbdev(usbif);
+	int brightness;
+	char data[8];
+
+	ret = usb_control_msg(usbdev, usb_rcvctrlpipe(usbdev, 0),
+			      K90_REQUEST_STATUS,
+			      USB_DIR_IN | USB_TYPE_VENDOR |
+			      USB_RECIP_DEVICE, 0, 0, data, 8,
+			      USB_CTRL_SET_TIMEOUT);
+	if (ret < 0) {
+		dev_warn(dev, "Failed to get K90 initial state (error %d).\n",
+			 ret);
+		return -EIO;
+	}
+	brightness = data[4];
+	if (brightness < 0 || brightness > 3) {
+		dev_warn(dev,
+			 "Read invalid backlight brightness: %02hhx.\n",
+			 data[4]);
+		return -EIO;
+	}
+	return brightness;
+}
+
+static enum led_brightness k90_record_led_get(struct led_classdev *led_cdev)
+{
+	struct k90_led *led = container_of(led_cdev, struct k90_led, cdev);
+
+	return led->brightness;
+}
+
+static void k90_brightness_set(struct led_classdev *led_cdev,
+			       enum led_brightness brightness)
+{
+	struct k90_led *led = container_of(led_cdev, struct k90_led, cdev);
+
+	led->brightness = brightness;
+	schedule_work(&led->work);
+}
+
+static void k90_backlight_work(struct work_struct *work)
+{
+	int ret;
+	struct k90_led *led = container_of(work, struct k90_led, work);
+	struct device *dev;
+	struct usb_interface *usbif;
+	struct usb_device *usbdev;
+
+	if (led->removed)
+		return;
+
+	dev = led->cdev.dev->parent;
+	usbif = to_usb_interface(dev->parent);
+	usbdev = interface_to_usbdev(usbif);
+
+	ret = usb_control_msg(usbdev, usb_sndctrlpipe(usbdev, 0),
+			      K90_REQUEST_BRIGHTNESS,
+			      USB_DIR_OUT | USB_TYPE_VENDOR |
+			      USB_RECIP_DEVICE, led->brightness, 0,
+			      NULL, 0, USB_CTRL_SET_TIMEOUT);
+	if (ret != 0)
+		dev_warn(dev, "Failed to set backlight brightness (error: %d).\n",
+			 ret);
+}
+
+static void k90_record_led_work(struct work_struct *work)
+{
+	int ret;
+	struct k90_led *led = container_of(work, struct k90_led, work);
+	struct device *dev;
+	struct usb_interface *usbif;
+	struct usb_device *usbdev;
+	int value;
+
+	if (led->removed)
+		return;
+
+	dev = led->cdev.dev->parent;
+	usbif = to_usb_interface(dev->parent);
+	usbdev = interface_to_usbdev(usbif);
+
+	if (led->brightness > 0)
+		value = K90_MACRO_LED_ON;
+	else
+		value = K90_MACRO_LED_OFF;
+
+	ret = usb_control_msg(usbdev, usb_sndctrlpipe(usbdev, 0),
+			      K90_REQUEST_MACRO_MODE,
+			      USB_DIR_OUT | USB_TYPE_VENDOR |
+			      USB_RECIP_DEVICE, value, 0, NULL, 0,
+			      USB_CTRL_SET_TIMEOUT);
+	if (ret != 0)
+		dev_warn(dev, "Failed to set record LED state (error: %d).\n",
+			 ret);
+}
+
+/*
+ * Keyboard attributes
+ */
+
+static ssize_t k90_show_macro_mode(struct device *dev,
+				   struct device_attribute *attr, char *buf)
+{
+	int ret;
+	struct usb_interface *usbif = to_usb_interface(dev->parent);
+	struct usb_device *usbdev = interface_to_usbdev(usbif);
+	const char *macro_mode;
+	char data[8];
+
+	ret = usb_control_msg(usbdev, usb_rcvctrlpipe(usbdev, 0),
+			      K90_REQUEST_GET_MODE,
+			      USB_DIR_IN | USB_TYPE_VENDOR |
+			      USB_RECIP_DEVICE, 0, 0, data, 2,
+			      USB_CTRL_SET_TIMEOUT);
+	if (ret < 0) {
+		dev_warn(dev, "Failed to get K90 initial mode (error %d).\n",
+			 ret);
+		return -EIO;
+	}
+
+	switch (data[0]) {
+	case K90_MACRO_MODE_HW:
+		macro_mode = "HW";
+		break;
+
+	case K90_MACRO_MODE_SW:
+		macro_mode = "SW";
+		break;
+	default:
+		dev_warn(dev, "K90 in unknown mode: %02hhx.\n",
+			 data[0]);
+		return -EIO;
+	}
+
+	return snprintf(buf, PAGE_SIZE, "%s\n", macro_mode);
+}
+
+static ssize_t k90_store_macro_mode(struct device *dev,
+				    struct device_attribute *attr,
+				    const char *buf, size_t count)
+{
+	int ret;
+	struct usb_interface *usbif = to_usb_interface(dev->parent);
+	struct usb_device *usbdev = interface_to_usbdev(usbif);
+	__u16 value;
+
+	if (strncmp(buf, "SW", 2) == 0)
+		value = K90_MACRO_MODE_SW;
+	else if (strncmp(buf, "HW", 2) == 0)
+		value = K90_MACRO_MODE_HW;
+	else
+		return -EINVAL;
+
+	ret = usb_control_msg(usbdev, usb_sndctrlpipe(usbdev, 0),
+			      K90_REQUEST_MACRO_MODE,
+			      USB_DIR_OUT | USB_TYPE_VENDOR |
+			      USB_RECIP_DEVICE, value, 0, NULL, 0,
+			      USB_CTRL_SET_TIMEOUT);
+	if (ret != 0) {
+		dev_warn(dev, "Failed to set macro mode.\n");
+		return ret;
+	}
+
+	return count;
+}
+
+static ssize_t k90_show_current_profile(struct device *dev,
+					struct device_attribute *attr,
+					char *buf)
+{
+	int ret;
+	struct usb_interface *usbif = to_usb_interface(dev->parent);
+	struct usb_device *usbdev = interface_to_usbdev(usbif);
+	int current_profile;
+	char data[8];
+
+	ret = usb_control_msg(usbdev, usb_rcvctrlpipe(usbdev, 0),
+			      K90_REQUEST_STATUS,
+			      USB_DIR_IN | USB_TYPE_VENDOR |
+			      USB_RECIP_DEVICE, 0, 0, data, 8,
+			      USB_CTRL_SET_TIMEOUT);
+	if (ret < 0) {
+		dev_warn(dev, "Failed to get K90 initial state (error %d).\n",
+			 ret);
+		return -EIO;
+	}
+	current_profile = data[7];
+	if (current_profile < 1 || current_profile > 3) {
+		dev_warn(dev, "Read invalid current profile: %02hhx.\n",
+			 data[7]);
+		return -EIO;
+	}
+
+	return snprintf(buf, PAGE_SIZE, "%d\n", current_profile);
+}
+
+static ssize_t k90_store_current_profile(struct device *dev,
+					 struct device_attribute *attr,
+					 const char *buf, size_t count)
+{
+	int ret;
+	struct usb_interface *usbif = to_usb_interface(dev->parent);
+	struct usb_device *usbdev = interface_to_usbdev(usbif);
+	int profile;
+
+	if (kstrtoint(buf, 10, &profile))
+		return -EINVAL;
+	if (profile < 1 || profile > 3)
+		return -EINVAL;
+
+	ret = usb_control_msg(usbdev, usb_sndctrlpipe(usbdev, 0),
+			      K90_REQUEST_PROFILE,
+			      USB_DIR_OUT | USB_TYPE_VENDOR |
+			      USB_RECIP_DEVICE, profile, 0, NULL, 0,
+			      USB_CTRL_SET_TIMEOUT);
+	if (ret != 0) {
+		dev_warn(dev, "Failed to change current profile (error %d).\n",
+			 ret);
+		return ret;
+	}
+
+	return count;
+}
+
+static DEVICE_ATTR(macro_mode, 0644, k90_show_macro_mode, k90_store_macro_mode);
+static DEVICE_ATTR(current_profile, 0644, k90_show_current_profile,
+		   k90_store_current_profile);
+
+static struct attribute *k90_attrs[] = {
+	&dev_attr_macro_mode.attr,
+	&dev_attr_current_profile.attr,
+	NULL
+};
+
+static const struct attribute_group k90_attr_group = {
+	.attrs = k90_attrs,
+};
+
+/*
+ * Driver functions
+ */
+
+static int k90_init_backlight(struct hid_device *dev)
+{
+	int ret;
+	struct corsair_drvdata *drvdata = hid_get_drvdata(dev);
+	size_t name_sz;
+	char *name;
+
+	drvdata->backlight = kzalloc(sizeof(struct k90_led), GFP_KERNEL);
+	if (!drvdata->backlight) {
+		ret = -ENOMEM;
+		goto fail_backlight_alloc;
+	}
+
+	name_sz =
+	    strlen(dev_name(&dev->dev)) + sizeof(K90_BACKLIGHT_LED_SUFFIX);
+	name = kzalloc(name_sz, GFP_KERNEL);
+	if (!name) {
+		ret = -ENOMEM;
+		goto fail_name_alloc;
+	}
+	snprintf(name, name_sz, "%s" K90_BACKLIGHT_LED_SUFFIX,
+		 dev_name(&dev->dev));
+	drvdata->backlight->removed = 0;
+	drvdata->backlight->cdev.name = name;
+	drvdata->backlight->cdev.max_brightness = 3;
+	drvdata->backlight->cdev.brightness_set = k90_brightness_set;
+	drvdata->backlight->cdev.brightness_get = k90_backlight_get;
+	INIT_WORK(&drvdata->backlight->work, k90_backlight_work);
+	ret = led_classdev_register(&dev->dev, &drvdata->backlight->cdev);
+	if (ret != 0)
+		goto fail_register_cdev;
+
+	return 0;
+
+fail_register_cdev:
+	kfree(drvdata->backlight->cdev.name);
+fail_name_alloc:
+	kfree(drvdata->backlight);
+	drvdata->backlight = NULL;
+fail_backlight_alloc:
+	return ret;
+}
+
+static int k90_init_macro_functions(struct hid_device *dev)
+{
+	int ret;
+	struct corsair_drvdata *drvdata = hid_get_drvdata(dev);
+	struct k90_drvdata *k90;
+	size_t name_sz;
+	char *name;
+
+	k90 = kzalloc(sizeof(struct k90_drvdata), GFP_KERNEL);
+	if (!k90) {
+		ret = -ENOMEM;
+		goto fail_drvdata;
+	}
+	drvdata->k90 = k90;
+
+	/* Init LED device for record LED */
+	name_sz = strlen(dev_name(&dev->dev)) + sizeof(K90_RECORD_LED_SUFFIX);
+	name = kzalloc(name_sz, GFP_KERNEL);
+	if (!name) {
+		ret = -ENOMEM;
+		goto fail_record_led_alloc;
+	}
+	snprintf(name, name_sz, "%s" K90_RECORD_LED_SUFFIX,
+		 dev_name(&dev->dev));
+	k90->record_led.removed = 0;
+	k90->record_led.cdev.name = name;
+	k90->record_led.cdev.max_brightness = 1;
+	k90->record_led.cdev.brightness_set = k90_brightness_set;
+	k90->record_led.cdev.brightness_get = k90_record_led_get;
+	INIT_WORK(&k90->record_led.work, k90_record_led_work);
+	k90->record_led.brightness = 0;
+	ret = led_classdev_register(&dev->dev, &k90->record_led.cdev);
+	if (ret != 0)
+		goto fail_record_led;
+
+	/* Init attributes */
+	ret = sysfs_create_group(&dev->dev.kobj, &k90_attr_group);
+	if (ret != 0)
+		goto fail_sysfs;
+
+	return 0;
+
+fail_sysfs:
+	k90->record_led.removed = 1;
+	led_classdev_unregister(&k90->record_led.cdev);
+	cancel_work_sync(&k90->record_led.work);
+fail_record_led:
+	kfree(k90->record_led.cdev.name);
+fail_record_led_alloc:
+	kfree(k90);
+fail_drvdata:
+	drvdata->k90 = NULL;
+	return ret;
+}
+
+static void k90_cleanup_backlight(struct hid_device *dev)
+{
+	struct corsair_drvdata *drvdata = hid_get_drvdata(dev);
+
+	if (drvdata->backlight) {
+		drvdata->backlight->removed = 1;
+		led_classdev_unregister(&drvdata->backlight->cdev);
+		cancel_work_sync(&drvdata->backlight->work);
+		kfree(drvdata->backlight->cdev.name);
+		kfree(drvdata->backlight);
+	}
+}
+
+static void k90_cleanup_macro_functions(struct hid_device *dev)
+{
+	struct corsair_drvdata *drvdata = hid_get_drvdata(dev);
+	struct k90_drvdata *k90 = drvdata->k90;
+
+	if (k90) {
+		sysfs_remove_group(&dev->dev.kobj, &k90_attr_group);
+
+		k90->record_led.removed = 1;
+		led_classdev_unregister(&k90->record_led.cdev);
+		cancel_work_sync(&k90->record_led.work);
+		kfree(k90->record_led.cdev.name);
+
+		kfree(k90);
+	}
+}
+
+static int corsair_probe(struct hid_device *dev, const struct hid_device_id *id)
+{
+	int ret;
+	unsigned long quirks = id->driver_data;
+	struct corsair_drvdata *drvdata;
+	struct usb_interface *usbif = to_usb_interface(dev->dev.parent);
+
+	drvdata = devm_kzalloc(&dev->dev, sizeof(struct corsair_drvdata),
+			       GFP_KERNEL);
+	if (drvdata == NULL)
+		return -ENOMEM;
+	drvdata->quirks = quirks;
+	hid_set_drvdata(dev, drvdata);
+
+	ret = hid_parse(dev);
+	if (ret != 0) {
+		hid_err(dev, "parse failed\n");
+		return ret;
+	}
+	ret = hid_hw_start(dev, HID_CONNECT_DEFAULT);
+	if (ret != 0) {
+		hid_err(dev, "hw start failed\n");
+		return ret;
+	}
+
+	if (usbif->cur_altsetting->desc.bInterfaceNumber == 0) {
+		if (quirks & CORSAIR_USE_K90_MACRO) {
+			ret = k90_init_macro_functions(dev);
+			if (ret != 0)
+				hid_warn(dev, "Failed to initialize K90 macro functions.\n");
+		}
+		if (quirks & CORSAIR_USE_K90_BACKLIGHT) {
+			ret = k90_init_backlight(dev);
+			if (ret != 0)
+				hid_warn(dev, "Failed to initialize K90 backlight.\n");
+		}
+	}
+
+	return 0;
+}
+
+static void corsair_remove(struct hid_device *dev)
+{
+	k90_cleanup_macro_functions(dev);
+	k90_cleanup_backlight(dev);
+
+	hid_hw_stop(dev);
+}
+
+static int corsair_event(struct hid_device *dev, struct hid_field *field,
+			 struct hid_usage *usage, __s32 value)
+{
+	struct corsair_drvdata *drvdata = hid_get_drvdata(dev);
+
+	if (!drvdata->k90)
+		return 0;
+
+	switch (usage->hid & HID_USAGE) {
+	case CORSAIR_USAGE_MACRO_RECORD_START:
+		drvdata->k90->record_led.brightness = 1;
+		break;
+	case CORSAIR_USAGE_MACRO_RECORD_STOP:
+		drvdata->k90->record_led.brightness = 0;
+		break;
+	default:
+		break;
+	}
+
+	return 0;
+}
+
+static int corsair_input_mapping(struct hid_device *dev,
+				 struct hid_input *input,
+				 struct hid_field *field,
+				 struct hid_usage *usage, unsigned long **bit,
+				 int *max)
+{
+	int gkey;
+
+	gkey = corsair_usage_to_gkey(usage->hid & HID_USAGE);
+	if (gkey != 0) {
+		hid_map_usage_clear(input, usage, bit, max, EV_KEY,
+				    corsair_gkey_map[gkey - 1]);
+		return 1;
+	}
+	if ((usage->hid & HID_USAGE) >= CORSAIR_USAGE_SPECIAL_MIN &&
+	    (usage->hid & HID_USAGE) <= CORSAIR_USAGE_SPECIAL_MAX) {
+		switch (usage->hid & HID_USAGE) {
+		case CORSAIR_USAGE_MACRO_RECORD_START:
+			hid_map_usage_clear(input, usage, bit, max, EV_KEY,
+					    corsair_record_keycodes[0]);
+			return 1;
+
+		case CORSAIR_USAGE_MACRO_RECORD_STOP:
+			hid_map_usage_clear(input, usage, bit, max, EV_KEY,
+					    corsair_record_keycodes[1]);
+			return 1;
+
+		case CORSAIR_USAGE_M1:
+			hid_map_usage_clear(input, usage, bit, max, EV_KEY,
+					    corsair_profile_keycodes[0]);
+			return 1;
+
+		case CORSAIR_USAGE_M2:
+			hid_map_usage_clear(input, usage, bit, max, EV_KEY,
+					    corsair_profile_keycodes[1]);
+			return 1;
+
+		case CORSAIR_USAGE_M3:
+			hid_map_usage_clear(input, usage, bit, max, EV_KEY,
+					    corsair_profile_keycodes[2]);
+			return 1;
+
+		default:
+			return -1;
+		}
+	}
+
+	return 0;
+}
+
+static const struct hid_device_id corsair_devices[] = {
+	{ HID_USB_DEVICE(USB_VENDOR_ID_CORSAIR, USB_DEVICE_ID_CORSAIR_K90),
+		.driver_data = CORSAIR_USE_K90_MACRO |
+			       CORSAIR_USE_K90_BACKLIGHT },
+	{}
+};
+
+MODULE_DEVICE_TABLE(hid, corsair_devices);
+
+static struct hid_driver corsair_driver = {
+	.name = "corsair",
+	.id_table = corsair_devices,
+	.probe = corsair_probe,
+	.event = corsair_event,
+	.remove = corsair_remove,
+	.input_mapping = corsair_input_mapping,
+};
+
+static int __init corsair_init(void)
+{
+	return hid_register_driver(&corsair_driver);
+}
+
+static void corsair_exit(void)
+{
+	hid_unregister_driver(&corsair_driver);
+}
+
+module_init(corsair_init);
+module_exit(corsair_exit);
+
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Clement Vuchener");
+MODULE_DESCRIPTION("HID driver for Corsair devices");

drivers/hid/hid-ids.h

···
 #define USB_DEVICE_ID_CODEMERCS_IOW_FIRST	0x1500
 #define USB_DEVICE_ID_CODEMERCS_IOW_LAST	0x15ff
 
+#define USB_VENDOR_ID_CORSAIR		0x1b1c
+#define USB_DEVICE_ID_CORSAIR_K90	0x1b02
+
 #define USB_VENDOR_ID_CREATIVELABS	0x041e
 #define USB_DEVICE_ID_PRODIKEYS_PCMIDI	0x2801