appledisplay.c

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/*
 * Apple Cinema Display driver
 *
 * Copyright (C) 2006  Michael Hanselmann ([email protected])
 *
 * Thanks to Caskey L. Dickson for his work with acdctl.
 *
 * 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., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
 */

#include <linux/kernel.h>
#include <linux/errno.h>
#include <linux/init.h>
#include <linux/module.h>
#include <linux/slab.h>
#include <linux/usb.h>
#include <linux/backlight.h>
#include <linux/timer.h>
#include <linux/workqueue.h>
#include <linux/atomic.h>

#define APPLE_VENDOR_ID     0x05AC

#define USB_REQ_GET_REPORT  0x01
#define USB_REQ_SET_REPORT  0x09

#define ACD_USB_TIMEOUT     250

#define ACD_USB_EDID        0x0302
#define ACD_USB_BRIGHTNESS  0x0310

#define ACD_BTN_NONE        0
#define ACD_BTN_BRIGHT_UP   3
#define ACD_BTN_BRIGHT_DOWN 4

#define ACD_URB_BUFFER_LEN  2
#define ACD_MSG_BUFFER_LEN  2

#define APPLEDISPLAY_DEVICE(prod)               \
    .match_flags = USB_DEVICE_ID_MATCH_DEVICE |     \
               USB_DEVICE_ID_MATCH_INT_CLASS |      \
               USB_DEVICE_ID_MATCH_INT_PROTOCOL,    \
    .idVendor = APPLE_VENDOR_ID,                \
    .idProduct = (prod),                    \
    .bInterfaceClass = USB_CLASS_HID,           \
    .bInterfaceProtocol = 0x00

/* table of devices that work with this driver */
static const struct usb_device_id appledisplay_table[] = {
    { APPLEDISPLAY_DEVICE(0x9218) },
    { APPLEDISPLAY_DEVICE(0x9219) },
    { APPLEDISPLAY_DEVICE(0x921c) },
    { APPLEDISPLAY_DEVICE(0x921d) },

    /* Terminating entry */
    { }
};
MODULE_DEVICE_TABLE(usb, appledisplay_table);

/* Structure to hold all of our device specific stuff */
struct appledisplay {
    struct usb_device *udev;    /* usb device */
    struct urb *urb;        /* usb request block */
    struct backlight_device *bd;    /* backlight device */
    u8 *urbdata;            /* interrupt URB data buffer */
    u8 *msgdata;            /* control message data buffer */

    struct delayed_work work;
    int button_pressed;
    spinlock_t lock;
};

static atomic_t count_displays = ATOMIC_INIT(0);
static struct workqueue_struct *wq;

static void appledisplay_complete(struct urb *urb)
{
    struct appledisplay *pdata = urb->context;
    struct device *dev = &pdata->udev->dev;
    unsigned long flags;
    int status = urb->status;
    int retval;

    switch (status) {
    case 0:
        /* success */
        break;
    case -EOVERFLOW:
        dev_err(dev,
            "OVERFLOW with data length %d, actual length is %d\n",
            ACD_URB_BUFFER_LEN, pdata->urb->actual_length);
    case -ECONNRESET:
    case -ENOENT:
    case -ESHUTDOWN:
        /* This urb is terminated, clean up */
        dev_dbg(dev, "%s - urb shuttingdown with status: %d\n",
            __func__, status);
        return;
    default:
        dev_dbg(dev, "%s - nonzero urb status received: %d/n",
            __func__, status);
        goto exit;
    }

    spin_lock_irqsave(&pdata->lock, flags);

    switch(pdata->urbdata[1]) {
    case ACD_BTN_BRIGHT_UP:
    case ACD_BTN_BRIGHT_DOWN:
        pdata->button_pressed = 1;
        queue_delayed_work(wq, &pdata->work, 0);
        break;
    case ACD_BTN_NONE:
    default:
        pdata->button_pressed = 0;
        break;
    }

    spin_unlock_irqrestore(&pdata->lock, flags);

exit:
    retval = usb_submit_urb(pdata->urb, GFP_ATOMIC);
    if (retval) {
        dev_err(dev, "%s - usb_submit_urb failed with result %d\n",
            __func__, retval);
    }
}

static int appledisplay_bl_update_status(struct backlight_device *bd)
{
    struct appledisplay *pdata = bl_get_data(bd);
    int retval;

    pdata->msgdata[0] = 0x10;
    pdata->msgdata[1] = bd->props.brightness;

    retval = usb_control_msg(
        pdata->udev,
        usb_sndctrlpipe(pdata->udev, 0),
        USB_REQ_SET_REPORT,
        USB_DIR_OUT | USB_TYPE_CLASS | USB_RECIP_INTERFACE,
        ACD_USB_BRIGHTNESS,
        0,
        pdata->msgdata, 2,
        ACD_USB_TIMEOUT);

    return retval;
}

static int appledisplay_bl_get_brightness(struct backlight_device *bd)
{
    struct appledisplay *pdata = bl_get_data(bd);
    int retval;

    retval = usb_control_msg(
        pdata->udev,
        usb_rcvctrlpipe(pdata->udev, 0),
        USB_REQ_GET_REPORT,
        USB_DIR_IN | USB_TYPE_CLASS | USB_RECIP_INTERFACE,
        ACD_USB_BRIGHTNESS,
        0,
        pdata->msgdata, 2,
        ACD_USB_TIMEOUT);

    if (retval < 0)
        return retval;
    else
        return pdata->msgdata[1];
}

static const struct backlight_ops appledisplay_bl_data = {
    .get_brightness = appledisplay_bl_get_brightness,
    .update_status  = appledisplay_bl_update_status,
};

static void appledisplay_work(struct work_struct *work)
{
    struct appledisplay *pdata =
        container_of(work, struct appledisplay, work.work);
    int retval;

    retval = appledisplay_bl_get_brightness(pdata->bd);
    if (retval >= 0)
        pdata->bd->props.brightness = retval;

    /* Poll again in about 125ms if there's still a button pressed */
    if (pdata->button_pressed)
        schedule_delayed_work(&pdata->work, HZ / 8);
}

static int appledisplay_probe(struct usb_interface *iface,
    const struct usb_device_id *id)
{
    struct backlight_properties props;
    struct appledisplay *pdata;
    struct usb_device *udev = interface_to_usbdev(iface);
    struct usb_host_interface *iface_desc;
    struct usb_endpoint_descriptor *endpoint;
    int int_in_endpointAddr = 0;
    int i, retval = -ENOMEM, brightness;
    char bl_name[20];

    /* set up the endpoint information */
    /* use only the first interrupt-in endpoint */
    iface_desc = iface->cur_altsetting;
    for (i = 0; i < iface_desc->desc.bNumEndpoints; i++) {
        endpoint = &iface_desc->endpoint[i].desc;
        if (!int_in_endpointAddr && usb_endpoint_is_int_in(endpoint)) {
            /* we found an interrupt in endpoint */
            int_in_endpointAddr = endpoint->bEndpointAddress;
            break;
        }
    }
    if (!int_in_endpointAddr) {
        dev_err(&iface->dev, "Could not find int-in endpoint\n");
        return -EIO;
    }

    /* allocate memory for our device state and initialize it */
    pdata = kzalloc(sizeof(struct appledisplay), GFP_KERNEL);
    if (!pdata) {
        retval = -ENOMEM;
        dev_err(&iface->dev, "Out of memory\n");
        goto error;
    }

    pdata->udev = udev;

    spin_lock_init(&pdata->lock);
    INIT_DELAYED_WORK(&pdata->work, appledisplay_work);

    /* Allocate buffer for control messages */
    pdata->msgdata = kmalloc(ACD_MSG_BUFFER_LEN, GFP_KERNEL);
    if (!pdata->msgdata) {
        retval = -ENOMEM;
        dev_err(&iface->dev,
            "Allocating buffer for control messages failed\n");
        goto error;
    }

    /* Allocate interrupt URB */
    pdata->urb = usb_alloc_urb(0, GFP_KERNEL);
    if (!pdata->urb) {
        retval = -ENOMEM;
        dev_err(&iface->dev, "Allocating URB failed\n");
        goto error;
    }

    /* Allocate buffer for interrupt data */
    pdata->urbdata = usb_alloc_coherent(pdata->udev, ACD_URB_BUFFER_LEN,
        GFP_KERNEL, &pdata->urb->transfer_dma);
    if (!pdata->urbdata) {
        retval = -ENOMEM;
        dev_err(&iface->dev, "Allocating URB buffer failed\n");
        goto error;
    }

    /* Configure interrupt URB */
    usb_fill_int_urb(pdata->urb, udev,
        usb_rcvintpipe(udev, int_in_endpointAddr),
        pdata->urbdata, ACD_URB_BUFFER_LEN, appledisplay_complete,
        pdata, 1);
    if (usb_submit_urb(pdata->urb, GFP_KERNEL)) {
        retval = -EIO;
        dev_err(&iface->dev, "Submitting URB failed\n");
        goto error;
    }

    /* Register backlight device */
    snprintf(bl_name, sizeof(bl_name), "appledisplay%d",
        atomic_inc_return(&count_displays) - 1);
    memset(&props, 0, sizeof(struct backlight_properties));
    props.type = BACKLIGHT_RAW;
    props.max_brightness = 0xff;
    pdata->bd = backlight_device_register(bl_name, NULL, pdata,
                          &appledisplay_bl_data, &props);
    if (IS_ERR(pdata->bd)) {
        dev_err(&iface->dev, "Backlight registration failed\n");
        retval = PTR_ERR(pdata->bd);
        goto error;
    }

    /* Try to get brightness */
    brightness = appledisplay_bl_get_brightness(pdata->bd);

    if (brightness < 0) {
        retval = brightness;
        dev_err(&iface->dev,
            "Error while getting initial brightness: %d\n", retval);
        goto error;
    }

    /* Set brightness in backlight device */
    pdata->bd->props.brightness = brightness;

    /* save our data pointer in the interface device */
    usb_set_intfdata(iface, pdata);

    printk(KERN_INFO "appledisplay: Apple Cinema Display connected\n");

    return 0;

error:
    if (pdata) {
        if (pdata->urb) {
            usb_kill_urb(pdata->urb);
            if (pdata->urbdata)
                usb_free_coherent(pdata->udev, ACD_URB_BUFFER_LEN,
                    pdata->urbdata, pdata->urb->transfer_dma);
            usb_free_urb(pdata->urb);
        }
        if (pdata->bd && !IS_ERR(pdata->bd))
            backlight_device_unregister(pdata->bd);
        kfree(pdata->msgdata);
    }
    usb_set_intfdata(iface, NULL);
    kfree(pdata);
    return retval;
}

static void appledisplay_disconnect(struct usb_interface *iface)
{
    struct appledisplay *pdata = usb_get_intfdata(iface);

    if (pdata) {
        usb_kill_urb(pdata->urb);
        cancel_delayed_work(&pdata->work);
        backlight_device_unregister(pdata->bd);
        usb_free_coherent(pdata->udev, ACD_URB_BUFFER_LEN,
            pdata->urbdata, pdata->urb->transfer_dma);
        usb_free_urb(pdata->urb);
        kfree(pdata->msgdata);
        kfree(pdata);
    }

    printk(KERN_INFO "appledisplay: Apple Cinema Display disconnected\n");
}

static struct usb_driver appledisplay_driver = {
    .name       = "appledisplay",
    .probe      = appledisplay_probe,
    .disconnect = appledisplay_disconnect,
    .id_table   = appledisplay_table,
};

static int __init appledisplay_init(void)
{
    wq = create_singlethread_workqueue("appledisplay");
    if (!wq) {
        printk(KERN_ERR "appledisplay: Could not create work queue\n");
        return -ENOMEM;
    }

    return usb_register(&appledisplay_driver);
}

static void __exit appledisplay_exit(void)
{
    flush_workqueue(wq);
    destroy_workqueue(wq);
    usb_deregister(&appledisplay_driver);
}

MODULE_AUTHOR("Michael Hanselmann");
MODULE_DESCRIPTION("Apple Cinema Display driver");
MODULE_LICENSE("GPL");

module_init(appledisplay_init);
module_exit(appledisplay_exit);