Kernel Module to fix wrong button mapping of PowerA wired Nintendo Switch controller

Makefile

obj-m += powera_switch_fix.o

all:
	make -C /lib/modules/$(shell uname -r)/build M=$(PWD) modules

clean:
	make -C /lib/modules/$(shell uname -r)/build M=$(PWD) clean

powera_switch_fix.c

/**
 * Linux kernel module to fix up the wrong button mapping for the
 * PowerA Wired Nintendo Switch controller
 */
#include <linux/hid.h>
#include <linux/input.h>
#include <linux/module.h>

MODULE_VERSION("0.1");
MODULE_LICENSE("GPL");

static const struct hid_device_id hidTable[] = {
	{ HID_USB_DEVICE(0x20D6, 0xA711) },
	{ 0 },
};

// button mapping
static const unsigned int buttonmap[] = {
	[1]  = BTN_WEST,    // Y button
	[2]  = BTN_SOUTH,   // B button
	[3]  = BTN_EAST,    // A button
	[4]  = BTN_NORTH,   // X button
	[5]  = BTN_TL,      // L button
	[6]  = BTN_TR,      // R button
	[7]  = BTN_TL2,     // ZL button
	[8]  = BTN_TR2,     // ZR button
	[9]  = BTN_SELECT,  // - button
	[10] = BTN_START,   // + button
	[11] = BTN_THUMBL,  // left stick press
	[12] = BTN_THUMBR,  // right stick press
	[13] = BTN_MODE,    // home button
	[14] = BTN_C,       // camera button, not sure what else to map this to
};

static int my_mapping(struct hid_device *hdev, struct hid_input *hi,
		struct hid_field *field, struct hid_usage *usage,
		unsigned long **bit, int *max)
{
	if ((usage->hid & HID_USAGE_PAGE) == HID_UP_BUTTON) {
		unsigned int button = usage->hid & HID_USAGE;
		if (button >= ARRAY_SIZE(buttonmap))
			return -1;
		button = buttonmap[button];
		if (button == 0)
			return -1;
		hid_map_usage_clear(hi, usage, bit, max, EV_KEY, button);
		return 1;
	}
	return 0;
}

static struct hid_driver driver = {
	.name = "powera_switch_fix",
	.id_table = hidTable,
	.input_mapping = my_mapping,
};

static int __init my_init(void)
{
	printk(KERN_INFO "%s: module_init\n", driver.name);
	return hid_register_driver(&driver);
}

static void __exit my_exit(void)
{
	printk(KERN_INFO "%s: module_exit\n", driver.name);
	hid_unregister_driver(&driver);
}

module_init(my_init);
module_exit(my_exit);