// SPDX-License-Identifier: GPL-2.0+
/*
 * Apple Cinema Display driver
 *
 * Copyright (C) 2006  Michael Hanselmann (linux-kernel@hansmi.ch)
 *
 * Thanks to Caskey L. Dickson for his work with acdctl.
 */

#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) },
        { APPLEDISPLAY_DEVICE(0x9222) },
        { APPLEDISPLAY_DEVICE(0x9226) },
        { APPLEDISPLAY_DEVICE(0x9236) },

        /* 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;
        struct mutex sysfslock;         /* concurrent read and write */
};

static atomic_t count_displays = ATOMIC_INIT(0);

static void appledisplay_complete(struct urb *urb)
{
        struct appledisplay *pdata = urb->context;
        struct device *dev = &pdata->udev->dev;
        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);
                fallthrough;
        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;
        }

        switch(pdata->urbdata[1]) {
        case ACD_BTN_BRIGHT_UP:
        case ACD_BTN_BRIGHT_DOWN:
                pdata->button_pressed = 1;
                /*
                 * there is a window during which no device
                 * is registered
                 */
                if (pdata->bd )
                        schedule_delayed_work(&pdata->work, 0);
                break;
        case ACD_BTN_NONE:
        default:
                pdata->button_pressed = 0;
                break;
        }

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;

        mutex_lock(&pdata->sysfslock);
        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);
        mutex_unlock(&pdata->sysfslock);

        if (retval < 0)
                return retval;
        else
                return 0;
}

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

        mutex_lock(&pdata->sysfslock);
        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 < 2) {
                if (retval >= 0)
                        retval = -EMSGSIZE;
        } else {
                brightness = pdata->msgdata[1];
        }
        mutex_unlock(&pdata->sysfslock);

        if (retval < 0)
                return retval;
        else
                return brightness;
}

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 backlight_device *backlight;
        struct appledisplay *pdata;
        struct usb_device *udev = interface_to_usbdev(iface);
        struct usb_endpoint_descriptor *endpoint;
        int int_in_endpointAddr = 0;
        int retval, brightness;
        char bl_name[20];

        /* set up the endpoint information */
        /* use only the first interrupt-in endpoint */
        retval = usb_find_int_in_endpoint(iface->cur_altsetting, &endpoint);
        if (retval) {
                dev_err(&iface->dev, "Could not find int-in endpoint\n");
                return retval;
        }

        int_in_endpointAddr = endpoint->bEndpointAddress;

        /* allocate memory for our device state and initialize it */
        pdata = kzalloc_obj(struct appledisplay);
        if (!pdata) {
                retval = -ENOMEM;
                goto error;
        }

        pdata->udev = udev;

        INIT_DELAYED_WORK(&pdata->work, appledisplay_work);
        mutex_init(&pdata->sysfslock);

        /* Allocate buffer for control messages */
        pdata->msgdata = kmalloc(ACD_MSG_BUFFER_LEN, GFP_KERNEL);
        if (!pdata->msgdata) {
                retval = -ENOMEM;
                goto error;
        }

        /* Allocate interrupt URB */
        pdata->urb = usb_alloc_urb(0, GFP_KERNEL);
        if (!pdata->urb) {
                retval = -ENOMEM;
                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);
        pdata->urb->transfer_flags = URB_NO_TRANSFER_DMA_MAP;
        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;
        backlight = backlight_device_register(bl_name, NULL, pdata,
                                              &appledisplay_bl_data, &props);
        if (IS_ERR(backlight)) {
                dev_err(&iface->dev, "Backlight registration failed\n");
                retval = PTR_ERR(backlight);
                goto error;
        }
        pdata->bd = backlight;

        /* 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);
                        cancel_delayed_work_sync(&pdata->work);
                        usb_free_coherent(pdata->udev, ACD_URB_BUFFER_LEN,
                                        pdata->urbdata, pdata->urb->transfer_dma);
                        usb_free_urb(pdata->urb);
                }
                if (!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_sync(&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,
};
module_usb_driver(appledisplay_driver);

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