hid-emsff.c

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/*
 *  Force feedback support for EMS Trio Linker Plus II
 *
 *  Copyright (c) 2010 Ignaz Forster <[email protected]>
 */

/*
 * 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.
 *
 * 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.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
 */


#include <linux/hid.h>
#include <linux/input.h>
#include <linux/usb.h>
#include <linux/module.h>

#include "hid-ids.h"
#include "usbhid/usbhid.h"

struct emsff_device {
    struct hid_report *report;
};

static int emsff_play(struct input_dev *dev, void *data,
             struct ff_effect *effect)
{
    struct hid_device *hid = input_get_drvdata(dev);
    struct emsff_device *emsff = data;
    int weak, strong;

    weak = effect->u.rumble.weak_magnitude;
    strong = effect->u.rumble.strong_magnitude;

    dbg_hid("called with 0x%04x 0x%04x\n", strong, weak);

    weak = weak * 0xff / 0xffff;
    strong = strong * 0xff / 0xffff;

    emsff->report->field[0]->value[1] = weak;
    emsff->report->field[0]->value[2] = strong;

    dbg_hid("running with 0x%02x 0x%02x\n", strong, weak);
    usbhid_submit_report(hid, emsff->report, USB_DIR_OUT);

    return 0;
}

static int emsff_init(struct hid_device *hid)
{
    struct emsff_device *emsff;
    struct hid_report *report;
    struct hid_input *hidinput = list_first_entry(&hid->inputs,
                        struct hid_input, list);
    struct list_head *report_list =
            &hid->report_enum[HID_OUTPUT_REPORT].report_list;
    struct input_dev *dev = hidinput->input;
    int error;

    if (list_empty(report_list)) {
        hid_err(hid, "no output reports found\n");
        return -ENODEV;
    }

    report = list_first_entry(report_list, struct hid_report, list);
    if (report->maxfield < 1) {
        hid_err(hid, "no fields in the report\n");
        return -ENODEV;
    }

    if (report->field[0]->report_count < 7) {
        hid_err(hid, "not enough values in the field\n");
        return -ENODEV;
    }

    emsff = kzalloc(sizeof(struct emsff_device), GFP_KERNEL);
    if (!emsff)
        return -ENOMEM;

    set_bit(FF_RUMBLE, dev->ffbit);

    error = input_ff_create_memless(dev, emsff, emsff_play);
    if (error) {
        kfree(emsff);
        return error;
    }

    emsff->report = report;
    emsff->report->field[0]->value[0] = 0x01;
    emsff->report->field[0]->value[1] = 0x00;
    emsff->report->field[0]->value[2] = 0x00;
    emsff->report->field[0]->value[3] = 0x00;
    emsff->report->field[0]->value[4] = 0x00;
    emsff->report->field[0]->value[5] = 0x00;
    emsff->report->field[0]->value[6] = 0x00;
    usbhid_submit_report(hid, emsff->report, USB_DIR_OUT);

    hid_info(hid, "force feedback for EMS based devices by Ignaz Forster <[email protected]>\n");

    return 0;
}

static int ems_probe(struct hid_device *hdev, const struct hid_device_id *id)
{
    int ret;

    ret = hid_parse(hdev);
    if (ret) {
        hid_err(hdev, "parse failed\n");
        goto err;
    }

    ret = hid_hw_start(hdev, HID_CONNECT_DEFAULT & ~HID_CONNECT_FF);
    if (ret) {
        hid_err(hdev, "hw start failed\n");
        goto err;
    }

    ret = emsff_init(hdev);
    if (ret) {
        dev_err(&hdev->dev, "force feedback init failed\n");
        hid_hw_stop(hdev);
        goto err;
    }

    return 0;
err:
    return ret;
}

static const struct hid_device_id ems_devices[] = {
    { HID_USB_DEVICE(USB_VENDOR_ID_EMS, USB_DEVICE_ID_EMS_TRIO_LINKER_PLUS_II) },
    { }
};
MODULE_DEVICE_TABLE(hid, ems_devices);

static struct hid_driver ems_driver = {
    .name = "hkems",
    .id_table = ems_devices,
    .probe = ems_probe,
};

static int ems_init(void)
{
    return hid_register_driver(&ems_driver);
}

static void ems_exit(void)
{
    hid_unregister_driver(&ems_driver);
}

module_init(ems_init);
module_exit(ems_exit);
MODULE_LICENSE("GPL");