Asus eee-top touch screen

[Gabriele Turchi]

Hi all.

I've done some tests to use the touch screen included in the Asus 
eee-top PC under Fedora 10/11. From the first results, the touch screen 
was detected, but only the mouse button events are generated. I've 
googled around a bit to find a solution, but found nothing.

Looking into kernel and X sources, the more viable solution for me was 
to write a little kernel module, to modify a bit the event's stream to 
make them compatible with X needs.

My module is attached, even if I fully understand that this module could 
be the worst conceived and worst written ever... :-)

To be serious: my choice was to make the less invasive solution, and 
this module appear to reach the goal: my touch screen works well now. 
Maybe mine was the wrong approach, but I've found so little 
documentation on how to make a better one. I'll obviously accept any 
useful suggestion.

I hope this could be useful.

Gabriele Turchi

P.S.: Please CC me, I'm not subscribed, and my apologies for my horrible 
English.




/*
 *  HID driver for TouchPack touchscreen
 *  (ASUS eee top touch screen)
 *
 *  Copyright (c) 2009 Gabriele Turchi - gabriele.turchi@xxxxxxxx
 */

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

#include "hid-ids.h"

static int tp_input_mapping(struct hid_device *device, struct hid_input *hi,
		struct hid_field *field, struct hid_usage *usage,
		unsigned long **bit, int *max)
{
	/* This is needed for evdev compatibility: these events are (apparently) never generated, but
         * X11 evdev driver goes mad with it.
         */

	if ( (usage->hid & HID_USAGE_PAGE) == HID_UP_DIGITIZER) {
		printk(KERN_INFO "tp_input_mapping: discard HID_UP_DIGITIZER => 0x%04X\n", usage->hid);
		return -1;
	}

	return 0;
}

static int tp_event(struct hid_device *device, struct hid_field *field, struct hid_usage *usage, __s32 value)
{
	/* "Somewere" the right axis number is changed with the wrong one.
         * Here we restore the correct values.
         */

	if ( (usage->code == 0x02) || (usage->code == 0x03) )
		usage->code -= 2;
	return 0;
}


static const struct hid_device_id tp_devices[] = {
	{ HID_USB_DEVICE( 0x1bfd, 0x1688) },
	{ }
};
MODULE_DEVICE_TABLE(hid, tp_devices);

static struct hid_driver tp_driver = {
	.name = "touchpack",
	.id_table = tp_devices,
	.input_mapping = tp_input_mapping,
	.event = tp_event,
};

static int tp_init(void)
{
	return hid_register_driver(&tp_driver);
}

static void tp_exit(void)
{
	hid_unregister_driver(&tp_driver);
}

module_init(tp_init);
module_exit(tp_exit);
MODULE_LICENSE("GPL");

HID_COMPAT_LOAD_DRIVER(touchpack);

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