hid-primax.c

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/*
 * HID driver for primax and similar keyboards with in-band modifiers
 *
 * Copyright 2011 Google Inc. All Rights Reserved
 *
 * Author:
 *  Terry Lambert <[email protected]>
 *
 * This software is licensed under the terms of the GNU General Public
 * License version 2, as published by the Free Software Foundation, and
 * may be copied, distributed, and modified under those terms.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 */

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

#include "hid-ids.h"

static int px_raw_event(struct hid_device *hid, struct hid_report *report,
     u8 *data, int size)
{
    int idx = size;

    switch (report->id) {
    case 0:     /* keyboard input */
        /*
         * Convert in-band modifier key values into out of band
         * modifier bits and pull the key strokes from the report.
         * Thus a report data set which looked like:
         *
         * [00][00][E0][30][00][00][00][00]
         * (no modifier bits + "Left Shift" key + "1" key)
         *
         * Would be converted to:
         *
         * [01][00][00][30][00][00][00][00]
         * (Left Shift modifier bit + "1" key)
         *
         * As long as it's in the size range, the upper level
         * drivers don't particularly care if there are in-band
         * 0-valued keys, so they don't stop parsing.
         */
        while (--idx > 1) {
            if (data[idx] < 0xE0 || data[idx] > 0xE7)
                continue;
            data[0] |= (1 << (data[idx] - 0xE0));
            data[idx] = 0;
        }
        hid_report_raw_event(hid, HID_INPUT_REPORT, data, size, 0);
        return 1;

    default:    /* unknown report */
        /* Unknown report type; pass upstream */
        hid_info(hid, "unknown report type %d\n", report->id);
        break;
    }

    return 0;
}

static const struct hid_device_id px_devices[] = {
    { HID_USB_DEVICE(USB_VENDOR_ID_PRIMAX, USB_DEVICE_ID_PRIMAX_KEYBOARD) },
    { }
};
MODULE_DEVICE_TABLE(hid, px_devices);

static struct hid_driver px_driver = {
    .name = "primax",
    .id_table = px_devices,
    .raw_event = px_raw_event,
};

static int __init px_init(void)
{
    return hid_register_driver(&px_driver);
}

static void __exit px_exit(void)
{
    hid_unregister_driver(&px_driver);
}

module_init(px_init);
module_exit(px_exit);
MODULE_AUTHOR("Terry Lambert <[email protected]>");
MODULE_LICENSE("GPL");