drivers/hid/hid-speedlink.c

Source file repositories/reference/linux-study-clean/drivers/hid/hid-speedlink.c

File Facts

System
Linux kernel
Corpus path
drivers/hid/hid-speedlink.c
Extension
.c
Size
2203 bytes
Lines
80
Domain
Driver Families
Bucket
drivers/hid
Inferred role
Driver Families: implementation source
Status
source implementation candidate

Why This File Exists

Repeatable hardware-adapter layer. Deep compatibility for every driver is out of scope; this atlas records patterns, probe lifecycles, bus glue, IRQ/DMA usage, and links back to core abstractions.

Dependency Surface

Detected Declarations

Annotated Snippet

// SPDX-License-Identifier: GPL-2.0-or-later
/*
 *  HID driver for Speedlink Vicious and Divine Cezanne (USB mouse).
 *  Fixes "jumpy" cursor and removes nonexistent keyboard LEDS from
 *  the HID descriptor.
 *
 *  Copyright (c) 2011, 2013 Stefan Kriwanek <dev@stefankriwanek.de>
 */

/*
 */

#include <linux/device.h>
#include <linux/hid.h>
#include <linux/module.h>

#include "hid-ids.h"

static const struct hid_device_id speedlink_devices[] = {
	{ HID_USB_DEVICE(USB_VENDOR_ID_X_TENSIONS, USB_DEVICE_ID_SPEEDLINK_VAD_CEZANNE)},
	{ }
};

static int speedlink_input_mapping(struct hid_device *hdev,
		struct hid_input *hi,
		struct hid_field *field, struct hid_usage *usage,
		unsigned long **bit, int *max)
{
	/*
	 * The Cezanne mouse has a second "keyboard" USB endpoint for it is
	 * able to map keyboard events to the button presses.
	 * It sends a standard keyboard report descriptor, though, whose
	 * LEDs we ignore.
	 */
	switch (usage->hid & HID_USAGE_PAGE) {
	case HID_UP_LED:
		return -1;
	}
	return 0;
}

static int speedlink_event(struct hid_device *hdev, struct hid_field *field,
		struct hid_usage *usage, __s32 value)
{
	/* No other conditions due to usage_table. */

	/* This fixes the "jumpy" cursor occuring due to invalid events sent
	 * by the device. Some devices only send them with value==+256, others
	 * don't. However, catching abs(value)>=256 is restrictive enough not
	 * to interfere with devices that were bug-free (has been tested).
	 */
	if (abs(value) >= 256)
		return 1;
	/* Drop useless distance 0 events (on button clicks etc.) as well */
	if (value == 0)
		return 1;

	return 0;
}

MODULE_DEVICE_TABLE(hid, speedlink_devices);

static const struct hid_usage_id speedlink_grabbed_usages[] = {
	{ HID_GD_X, EV_REL, 0 },
	{ HID_GD_Y, EV_REL, 1 },
	{ HID_ANY_ID - 1, HID_ANY_ID - 1, HID_ANY_ID - 1}
};

static struct hid_driver speedlink_driver = {
	.name = "speedlink",
	.id_table = speedlink_devices,
	.usage_table = speedlink_grabbed_usages,
	.input_mapping = speedlink_input_mapping,
	.event = speedlink_event,
};
module_hid_driver(speedlink_driver);

MODULE_DESCRIPTION("HID driver for Speedlink Vicious and Divine Cezanne (USB mouse)");
MODULE_LICENSE("GPL");

Annotation

Implementation Notes