HID: mcp2200: added driver for GPIOs of MCP2200

Added a gpiochip compatible driver to control the 8 GPIOs of
the MCP2200 by using the HID interface.

Using GPIOs with alternative functions (GP0<->SSPND, GP1<->USBCFG,
GP6<->RXLED, GP7<->TXLED) will reset the functions, if set (unset by
default).

The driver was tested while also using the UART of the chip. Setting
and reading the GPIOs has no effect on the UART communication. However,
a reset is triggered after the CONFIGURE command. If the GPIO Direction
is constantly changed, this will affect the communication at low baud
rates. This is a hardware problem of the MCP2200 and is not caused by
the driver.

Signed-off-by: Johannes Roith <johannes@gnu-linux.rocks>
Reviewed-by: Rahul Rameshbabu <sergeantsagara@protonmail.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>

Author: Johannes Roith

drivers/hid/Kconfig

@@ -1296,6 +1296,15 @@ config HID_ALPS
 	Say Y here if you have a Alps touchpads over i2c-hid or usbhid
 	and want support for its special functionalities.
 
+config HID_MCP2200
+	tristate "Microchip MCP2200 HID USB-to-GPIO bridge"
+	depends on USB_HID && GPIOLIB
+	help
+	  Provides GPIO functionality over USB-HID through MCP2200 device.
+
+	  To compile this driver as a module, choose M here: the module
+	  will be called hid-mcp2200.ko.
+
 config HID_MCP2221
 	tristate "Microchip MCP2221 HID USB-to-I2C/SMbus host support"
 	depends on USB_HID && I2C

drivers/hid/Makefile

@@ -79,6 +79,7 @@ obj-$(CONFIG_HID_LOGITECH_HIDPP)	+= hid-logitech-hidpp.o
 obj-$(CONFIG_HID_MACALLY)	+= hid-macally.o
 obj-$(CONFIG_HID_MAGICMOUSE)	+= hid-magicmouse.o
 obj-$(CONFIG_HID_MALTRON)	+= hid-maltron.o
+obj-$(CONFIG_HID_MCP2200)	+= hid-mcp2200.o
 obj-$(CONFIG_HID_MCP2221)	+= hid-mcp2221.o
 obj-$(CONFIG_HID_MAYFLASH)	+= hid-mf.o
 obj-$(CONFIG_HID_MEGAWORLD_FF)	+= hid-megaworld.o

drivers/hid/hid-ids.h

@@ -917,6 +917,7 @@
 #define USB_DEVICE_ID_PICK16F1454	0x0042
 #define USB_DEVICE_ID_PICK16F1454_V2	0xf2f7
 #define USB_DEVICE_ID_LUXAFOR		0xf372
+#define USB_DEVICE_ID_MCP2200		0x00df
 #define USB_DEVICE_ID_MCP2221		0x00dd
 
 #define USB_VENDOR_ID_MICROSOFT		0x045e