Fix modifier keys for Redragon Asura Keyboard

Changelog:

- v2: modifier keys work, some combinations are still troublesome

The microdia family of keyboards uses a non-standard way of sending modifier keys.

The down event always sets the first bit to 0x04 and the second keycode to a custom value For instance, left shift sends the following bits

04 02 00 00 00 00 00 00

while left control sends

04 01 00 00 00 00 00 00

As a result all modifier keys are mapped to left shift and the keyboard is non-functional in that respect. To solve the problem, we capture the raw data in raw_event and manually genereate the correct input events.

The keyboard functions mostly as expected now, with only a few minor issues;

- two USB devices are detected instead of 1
- some key combinations are not triggered - e.g. left shift + left ctrl + p. However, the same combination is recognized with the right shift key.

The printk calls will be removed for the final submission.

Tested on Kernel 4.11.4.

---
 drivers/hid/Kconfig        |   7 +++
 drivers/hid/Makefile       |   2 +-
 drivers/hid/hid-core.c     |   1 +
 drivers/hid/hid-ids.h      |   3 +
 drivers/hid/hid-microdia.c | 147 +++++++++++++++++++++++++++++++++++++++++++++
 5 files changed, 159 insertions(+), 1 deletion(-)
 create mode 100644 drivers/hid/hid-microdia.c

index 8c54cb8f5d6d..ef950b11ffbe 100644
@@ -521,6 +521,13 @@ config HID_MAYFLASH
 	Say Y here if you have HJZ Mayflash PS3 game controller adapters
 	and want to enable force feedback support.
 
+config HID_MICRODIA
+	tristate "Microdia based keyboards"
+	depends on HID
+	default !EXPERT
+	---help---
+    Support for Microdia based keyboards such as the Redragon Asura.
+
 config HID_MICROSOFT
 	tristate "Microsoft non-fully HID-compliant devices"
 	depends on HID

index 4d111f23e801..72dcfa925086 100644
@@ -59,6 +59,7 @@ obj-$(CONFIG_HID_LOGITECH_DJ)	+= hid-logitech-dj.o
 obj-$(CONFIG_HID_LOGITECH_HIDPP)	+= hid-logitech-hidpp.o
 obj-$(CONFIG_HID_MAGICMOUSE)	+= hid-magicmouse.o
 obj-$(CONFIG_HID_MAYFLASH)	+= hid-mf.o
+obj-$(CONFIG_HID_MICRODIA)  += hid-microdia.o
 obj-$(CONFIG_HID_MICROSOFT)	+= hid-microsoft.o
 obj-$(CONFIG_HID_MONTEREY)	+= hid-monterey.o
 obj-$(CONFIG_HID_MULTITOUCH)	+= hid-multitouch.o

@@ -116,4 +117,3 @@ obj-$(CONFIG_USB_KBD)		+= usbhid/
 
 obj-$(CONFIG_I2C_HID)		+= i2c-hid/
 
-obj-$(CONFIG_INTEL_ISH_HID)	+= intel-ish-hid/

index d162f0dc76e3..7a54ab0a59b1 100644
@@ -1974,6 +1974,7 @@ static const struct hid_device_id hid_have_special_driver[] = {
 	{ HID_USB_DEVICE(USB_VENDOR_ID_MICROCHIP, USB_DEVICE_ID_PICOLCD) },
 	{ HID_USB_DEVICE(USB_VENDOR_ID_MICROCHIP, USB_DEVICE_ID_PICOLCD_BOOTLOADER) },
 	{ HID_USB_DEVICE(USB_VENDOR_ID_MICROCHIP, USB_DEVICE_ID_LUXAFOR) },
+	{ HID_USB_DEVICE(USB_VENDOR_ID_MICRODIA,  USB_DEVICE_ID_REDRAGON_ASURA) },
 	{ HID_USB_DEVICE(USB_VENDOR_ID_MICROSOFT, USB_DEVICE_ID_MS_COMFORT_MOUSE_4500) },
 	{ HID_USB_DEVICE(USB_VENDOR_ID_MICROSOFT, USB_DEVICE_ID_MS_COMFORT_KEYBOARD) },
 	{ HID_USB_DEVICE(USB_VENDOR_ID_MICROSOFT, USB_DEVICE_ID_SIDEWINDER_GV) },

index b26c030926c1..7e4f716c3a98 100644
@@ -1127,4 +1127,7 @@
 #define USB_VENDOR_ID_UGTIZER			0x2179
 #define USB_DEVICE_ID_UGTIZER_TABLET_GP0610	0x0053
 
+#define USB_VENDOR_ID_MICRODIA          0x0c45
+#define USB_DEVICE_ID_REDRAGON_ASURA    0x760b
+
 #endif

2.13.1

Hi Michel,

I am not sure about the correctness of the approach, thus the RFC :-)

It was also quite easy for me to discover the behaviour when using a new module, but with the existing code base I find it harder to navigate.

Can you point me to where the hid codes are parsed? Is it hidinput_setkeycode in hid-input.c?

Thanks,

Robert