[PATCH 2/2] HID: corsair: Add driver Scimitar Pro RGB gaming mouse 1b1c:1b3e

[Oscar Campos <oscar.campos@member.fsf.org>]

This mouse sold by Corsair as Scimitar PRO RGB defines two consecutive
Logical Minimum items in its Application (Consumer.0001) report making
it non parseable. This driver fixes the report descriptor overriding
byte 77 in rdesc from 0x16 (Logical Minimum with 16 bits value) to 0x26
(Logical Maximum with 16 bits value).

Signed-off-by: Oscar Campos <oscar.campos@member.fsf.org>
---
 drivers/hid/Kconfig             | 10 ++++++
 drivers/hid/Makefile            |  1 +
 drivers/hid/hid-corsair-mouse.c | 76 +++++++++++++++++++++++++++++++++++++++++
 3 files changed, 87 insertions(+)
 create mode 100644 drivers/hid/hid-corsair-mouse.c

diff --git a/drivers/hid/Kconfig b/drivers/hid/Kconfig
index 4070b7386e9d..1ad179b70b15 100644
--- a/drivers/hid/Kconfig
+++ b/drivers/hid/Kconfig
@@ -191,6 +191,16 @@ config HID_CORSAIR
 	Supported devices:
 	- Vengeance K90

+config HID_CORSAIR_MOUSE:
+    tristate "Corsair mice"
+    depends on HID && USB
+    ---help---
+    Support for Corsair mice devices that are not fully compliant with
+    the HID standard.
+
+    Supported devices:
+    - Scimitar Pro RGB
+
 config HID_PRODIKEYS
 	tristate "Prodikeys PC-MIDI Keyboard support"
 	depends on HID && SND
diff --git a/drivers/hid/Makefile b/drivers/hid/Makefile
index 4d111f23e801..34d17e9b4640 100644
--- a/drivers/hid/Makefile
+++ b/drivers/hid/Makefile
@@ -33,6 +33,7 @@ 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-$(CONFIG_HID_CORSAIR_MOUSE)	+= hid-corsair-mouse.o
 obj-$(CONFIG_HID_CP2112)	+= hid-cp2112.o
 obj-$(CONFIG_HID_CYPRESS)	+= hid-cypress.o
 obj-$(CONFIG_HID_DRAGONRISE)	+= hid-dr.o
diff --git a/drivers/hid/hid-corsair-mouse.c b/drivers/hid/hid-corsair-mouse.c
new file mode 100644
index 000000000000..3f6d6f6cc246
--- /dev/null
+++ b/drivers/hid/hid-corsair-mouse.c
@@ -0,0 +1,76 @@
+/*
+ * HID driver for Corsair mouse devices
+ *
+ * Supported devices:
+ *  - Scimitar RGB Pro
+ *
+ * Copyright (c) 2017 Oscar Campos
+ */
+
+/*
+ * 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 "hid-ids.h"
+
+/*
+ * The report descriptor of Corsair Scimitar RGB Pro gaming mouse is
+ * non parseable as they define two consecutive Logical Minimum for
+ * the Usage Page (Consumer) in rdescs bytes 75 and 77 being 77 0x16
+ * that should be obviousy 0x26 for Logical Magimum of 16 bits. This
+ * prevents poper parsing of the report descriptor due Logical
+ * Minimum being larger than Logical Maximum.
+ *
+ * This driver fixes the report descriptor for:
+ * - USB ID b1c:1b3e, sold as Scimitar RGB Pro Gaming mouse
+ */
+
+static __u8 *corsair_mouse_report_fixup(struct hid_device *hdev, __u8 *rdesc,
+		unsigned int *rsize)
+{
+	struct usb_interface *intf = to_usb_interface(hdev->dev.parent);
+
+	if (intf->cur_altsetting->desc.bInterfaceNumber == 1) {
+		/*
+		 * Corsair Scimitar RGB Pro report descriptor is broken and
+		 * defines two different Logical Minimum for the Consumer
+		 * Application. The byte 77 should be a 0x26 defining a 16
+		 * bits integer for the Logical Maximum but it is a 0x16
+		 * instead (Logical Minimum)
+		 */
+		switch (hdev->product) {
+		case USB_DEVICE_ID_CORSAIR_SCIMITAR_PRO_RGB:
+			if (*rsize >= 172 && rdesc[75] == 0x15 && rdesc[77] == 0x16
+					&& rdesc[78] == 0xff && rdesc[79] == 0x0f) {
+				hid_info(hdev, "Fixing up report descriptor\n");
+				rdesc[77] = 0x26;
+			}
+			break;
+		}
+
+	}
+	return rdesc;
+}
+
+static const struct hid_device_id corsair_mouse_devices[] = {
+	{ HID_USB_DEVICE(USB_VENDOR_ID_CORSAIR,
+			USB_DEVICE_ID_CORSAIR_SCIMITAR_PRO_RGB) },
+	{ }
+};
+MODULE_DEVICE_TABLE(hid, corsair_mouse_devices);
+
+static struct hid_driver corsair_mouse_driver = {
+	.name = "corsair_mouse",
+	.id_table = corsair_mouse_devices,
+	.report_fixup = corsair_mouse_report_fixup,
+};
+
+module_hid_driver(corsair_mouse_driver);
+MODULE_LICENSE("GPL");
--
2.11.0