// SPDX-License-Identifier: GPL-2.0-only

#include <linux/string.h>

#include <drm/drm_drv.h>
#include <drm/drm_edid.h>
#include <drm/drm_print.h>

#include "udl_drv.h"
#include "udl_edid.h"

static int udl_read_edid_block(void *data, u8 *buf, unsigned int block, size_t len)
{
        struct udl_device *udl = data;
        struct drm_device *dev = &udl->drm;
        struct usb_device *udev = udl_to_usb_device(udl);
        u8 *read_buff;
        int idx, ret;
        size_t i;

        read_buff = kmalloc(2, GFP_KERNEL);
        if (!read_buff)
                return -ENOMEM;

        if (!drm_dev_enter(dev, &idx)) {
                ret = -ENODEV;
                goto err_kfree;
        }

        for (i = 0; i < len; i++) {
                int bval = (i + block * EDID_LENGTH) << 8;

                ret = usb_control_msg(udev, usb_rcvctrlpipe(udev, 0),
                                      0x02, (0x80 | (0x02 << 5)), bval,
                                      0xA1, read_buff, 2, USB_CTRL_GET_TIMEOUT);
                if (ret < 0) {
                        drm_err(dev, "Read EDID byte %zu failed err %x\n", i, ret);
                        goto err_drm_dev_exit;
                } else if (ret < 1) {
                        ret = -EIO;
                        drm_err(dev, "Read EDID byte %zu failed\n", i);
                        goto err_drm_dev_exit;
                }

                buf[i] = read_buff[1];
        }

        drm_dev_exit(idx);
        kfree(read_buff);

        return 0;

err_drm_dev_exit:
        drm_dev_exit(idx);
err_kfree:
        kfree(read_buff);
        return ret;
}

bool udl_probe_edid(struct udl_device *udl)
{
        u8 hdr[8];
        int ret;

        ret = udl_read_edid_block(udl, hdr, 0, sizeof(hdr));
        if (ret)
                return false;

        /*
         * The adapter sends all-zeros if no monitor has been
         * connected. We consider anything else a connection.
         */
        return !mem_is_zero(hdr, sizeof(hdr));
}

const struct drm_edid *udl_edid_read(struct drm_connector *connector)
{
        struct udl_device *udl = to_udl(connector->dev);

        return drm_edid_read_custom(connector, udl_read_edid_block, udl);
}