/*      $NetBSD: udl.c,v 1.35 2024/10/02 17:22:45 tsutsui Exp $ */

/*-
 * Copyright (c) 2009 FUKAUMI Naoki.
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

/*
 * Copyright (c) 2009 Marcus Glocker <mglocker@openbsd.org>
 *
 * Permission to use, copy, modify, and distribute this software for any
 * purpose with or without fee is hereby granted, provided that the above
 * copyright notice and this permission notice appear in all copies.
 *
 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 */

/*
 * Driver for the ``DisplayLink DL-1x0 / DL-1x5'' graphic chips based
 * on the reversed engineered specifications of Florian Echtler
 * <floe at butterbrot dot org>:
 *
 *      http://floe.butterbrot.org/displaylink/doku.php
 *
 * This driver was written by Marcus Glocker for OpenBSD and ported to
 * NetBSD by FUKAUMI Naoki with many modification.
 */

#include <sys/cdefs.h>
__KERNEL_RCSID(0, "$NetBSD: udl.c,v 1.35 2024/10/02 17:22:45 tsutsui Exp $");

#ifdef _KERNEL_OPT
#include "opt_usb.h"
#endif

#include <sys/param.h>
#include <sys/device.h>
#include <sys/kernel.h>
#include <sys/proc.h>
#include <sys/systm.h>
#include <sys/kmem.h>
#include <sys/kthread.h>
#include <sys/condvar.h>

#include <sys/bus.h>
#include <sys/endian.h>

#include <uvm/uvm_extern.h>

#include <dev/usb/usb.h>
#include <dev/usb/usbdi.h>
#include <dev/usb/usbdivar.h>
#include <dev/usb/usbdi_util.h>
#include <dev/usb/usb_mem.h>
#include <dev/usb/usbdevs.h>

#include <dev/firmload.h>

#include <dev/videomode/videomode.h>
#include <dev/videomode/edidvar.h>

#include <dev/wscons/wsconsio.h>
#include <dev/wscons/wsdisplayvar.h>
#include <dev/rasops/rasops.h>

#include <dev/usb/udl.h>
#ifdef notyet
#include <dev/usb/udlio.h>
#endif

/*
 * Defines.
 */
#ifdef UDL_DEBUG
#define DPRINTF(x)      do { if (udl_debug) printf x; } while (0)
#define DPRINTFN(n, x)  do { if (udl_debug >= (n)) printf x; } while (0)
int udl_debug = 1;
#else
#define DPRINTF(x)      do {} while (0)
#define DPRINTFN(n, x)  do {} while (0)
#endif

/*
 * Prototypes.
 */
static int              udl_match(device_t, cfdata_t, void *);
static void             udl_attach(device_t, device_t, void *);
static int              udl_detach(device_t, int);

static int              udl_ioctl(void *, void *, u_long, void *, int,
                            struct lwp *);
static paddr_t          udl_mmap(void *, void *, off_t, int);
static int              udl_alloc_screen(void *, const struct wsscreen_descr *,
                            void **, int *, int *, long *);
static void             udl_free_screen(void *, void *);
static int              udl_show_screen(void *, void *, int,
                            void (*)(void *, int, int), void *);

static void             udl_comp_load(struct udl_softc *);
static void             udl_comp_unload(struct udl_softc *);
static int              udl_fbmem_alloc(struct udl_softc *);
static void             udl_fbmem_free(struct udl_softc *);
static int              udl_cmdq_alloc(struct udl_softc *);
static void             udl_cmdq_free(struct udl_softc *);
static struct udl_cmdq *udl_cmdq_get(struct udl_softc *sc);
static void             udl_cmdq_put(struct udl_softc *sc,
                            struct udl_cmdq *cmdq);
static void             udl_cmdq_flush(struct udl_softc *);

static void             udl_cursor(void *, int, int, int);
static void             udl_putchar(void *, int, int, u_int, long);
static void             udl_copycols(void *, int, int, int, int);
static void             udl_erasecols(void *, int, int, int, long);
static void             udl_copyrows(void *, int, int, int);
static void             udl_eraserows(void *, int, int, long);

static void             udl_restore_char(struct rasops_info *);
static void             udl_draw_char(struct rasops_info *, uint16_t *, u_int,
                            int, int);
static void             udl_copy_rect(struct udl_softc *, int, int, int, int,
                            int, int);
static void             udl_fill_rect(struct udl_softc *, uint16_t, int, int,
                            int, int);
#ifdef notyet
static void             udl_draw_rect(struct udl_softc *,
                            struct udl_ioctl_damage *);
static void             udl_draw_rect_comp(struct udl_softc *,
                            struct udl_ioctl_damage *);
#endif

static inline void      udl_copy_line(struct udl_softc *, int, int, int);
static inline void      udl_fill_line(struct udl_softc *, uint16_t, int, int);
static inline void      udl_draw_line(struct udl_softc *, uint16_t *, int,
                            int);
#ifdef notyet
static inline void      udl_draw_line_comp(struct udl_softc *, uint16_t *, int,
                            int);
#endif

static int              udl_cmd_send(struct udl_softc *);
static void             udl_cmd_send_async(struct udl_softc *);
static void             udl_cmd_send_async_cb(struct usbd_xfer *,
                            void *, usbd_status);

static int              udl_ctrl_msg(struct udl_softc *, uint8_t, uint8_t,
                            uint16_t, uint16_t, uint8_t *, uint16_t);
static int              udl_init(struct udl_softc *);
static void             udl_read_edid(struct udl_softc *);
static void             udl_set_address(struct udl_softc *, int, int, int,
                            int);
static void             udl_blank(struct udl_softc *, int);
static uint16_t         udl_lfsr(uint16_t);
static int              udl_set_resolution(struct udl_softc *,
                            const struct videomode *);
static const struct videomode *udl_videomode_lookup(const char *);
static void             udl_update_thread(void *);
static inline void udl_startstop(struct udl_softc *, bool);

static inline void
udl_cmd_add_1(struct udl_softc *sc, uint8_t val)
{

        *sc->sc_cmd_buf++ = val;
}

static inline void
udl_cmd_add_2(struct udl_softc *sc, uint16_t val)
{

        be16enc(sc->sc_cmd_buf, val);
        sc->sc_cmd_buf += 2;
}

static inline void
udl_cmd_add_3(struct udl_softc *sc, uint32_t val)
{

        udl_cmd_add_2(sc, val >> 8);
        udl_cmd_add_1(sc, val);
}

static inline void
udl_cmd_add_4(struct udl_softc *sc, uint32_t val)
{

        be32enc(sc->sc_cmd_buf, val);
        sc->sc_cmd_buf += 4;
}

static inline void
udl_cmd_add_buf(struct udl_softc *sc, uint16_t *buf, int width)
{
#if BYTE_ORDER == BIG_ENDIAN
        memcpy(sc->sc_cmd_buf, buf, width * 2);
        sc->sc_cmd_buf += width * 2;
#else
        uint16_t *endp;

        endp = buf + width;

        if (((uintptr_t)sc->sc_cmd_buf & 1) == 0) {
                while (buf < endp) {
                        *(uint16_t *)sc->sc_cmd_buf = htobe16(*buf++);
                        sc->sc_cmd_buf += 2;
                }
        } else {
                while (buf < endp) {
                        be16enc(sc->sc_cmd_buf, *buf++);
                        sc->sc_cmd_buf += 2;
                }
        }
#endif
}

static inline void
udl_reg_write_1(struct udl_softc *sc, uint8_t reg, uint8_t val)
{

        udl_cmd_add_4(sc, (UDL_BULK_SOC << 24) |
            (UDL_BULK_CMD_REG_WRITE_1 << 16) | (reg << 8) | val);
}

static inline void
udl_reg_write_2(struct udl_softc *sc, uint8_t reg, uint16_t val)
{

        udl_reg_write_1(sc, reg++, val >> 8);
        udl_reg_write_1(sc, reg, val);
}

static inline void
udl_reg_write_3(struct udl_softc *sc, uint8_t reg, uint32_t val)
{

        udl_reg_write_1(sc, reg++, val >> 16);
        udl_reg_write_1(sc, reg++, val >> 8);
        udl_reg_write_1(sc, reg, val);
}

/* XXX */
static int
firmware_load(const char *dname, const char *iname, uint8_t **ucodep,
    size_t *sizep)
{
        firmware_handle_t fh;
        int error;

        if ((error = firmware_open(dname, iname, &fh)) != 0)
                return error;
        *sizep = firmware_get_size(fh);
        if ((*ucodep = firmware_malloc(*sizep)) == NULL) {
                firmware_close(fh);
                return ENOMEM;
        }
        if ((error = firmware_read(fh, 0, *ucodep, *sizep)) != 0)
                firmware_free(*ucodep, *sizep);
        firmware_close(fh);

        return error;
}

/*
 * Driver glue.
 */
CFATTACH_DECL_NEW(udl, sizeof(struct udl_softc),
        udl_match, udl_attach, udl_detach, NULL);

/*
 * wsdisplay glue.
 */
static struct wsdisplay_accessops udl_accessops = {
        udl_ioctl,
        udl_mmap,
        udl_alloc_screen,
        udl_free_screen,
        udl_show_screen,
        NULL,
        NULL,
        NULL,
};

/*
 * Matching devices.
 */
static const struct usb_devno udl_devs[] = {
        { USB_VENDOR_DISPLAYLINK, USB_PRODUCT_DISPLAYLINK_GUC2020 },
        { USB_VENDOR_DISPLAYLINK, USB_PRODUCT_DISPLAYLINK_LD220 },
        { USB_VENDOR_DISPLAYLINK, USB_PRODUCT_DISPLAYLINK_LD190 },
        { USB_VENDOR_DISPLAYLINK, USB_PRODUCT_DISPLAYLINK_U70 },
        { USB_VENDOR_DISPLAYLINK, USB_PRODUCT_DISPLAYLINK_POLARIS2 },
        { USB_VENDOR_DISPLAYLINK, USB_PRODUCT_DISPLAYLINK_VCUD60 },
        { USB_VENDOR_DISPLAYLINK, USB_PRODUCT_DISPLAYLINK_CONV },
        { USB_VENDOR_DISPLAYLINK, USB_PRODUCT_DISPLAYLINK_DLDVI },
        { USB_VENDOR_DISPLAYLINK, USB_PRODUCT_DISPLAYLINK_USBRGB },
        { USB_VENDOR_DISPLAYLINK, USB_PRODUCT_DISPLAYLINK_LCDUSB7X },
        { USB_VENDOR_DISPLAYLINK, USB_PRODUCT_DISPLAYLINK_LCDUSB10X },
        { USB_VENDOR_DISPLAYLINK, USB_PRODUCT_DISPLAYLINK_VGA10 },
        { USB_VENDOR_DISPLAYLINK, USB_PRODUCT_DISPLAYLINK_WSDVI },
        { USB_VENDOR_DISPLAYLINK, USB_PRODUCT_DISPLAYLINK_EC008 },
        { USB_VENDOR_DISPLAYLINK, USB_PRODUCT_DISPLAYLINK_GXDVIU2 },
        { USB_VENDOR_DISPLAYLINK, USB_PRODUCT_DISPLAYLINK_GXDVIU2B },
        { USB_VENDOR_DISPLAYLINK, USB_PRODUCT_DISPLAYLINK_LCD4300U },
        { USB_VENDOR_DISPLAYLINK, USB_PRODUCT_DISPLAYLINK_LCD8000U },
        { USB_VENDOR_DISPLAYLINK, USB_PRODUCT_DISPLAYLINK_HPDOCK },
        { USB_VENDOR_DISPLAYLINK, USB_PRODUCT_DISPLAYLINK_NL571 },
        { USB_VENDOR_DISPLAYLINK, USB_PRODUCT_DISPLAYLINK_M01061 },
        { USB_VENDOR_DISPLAYLINK, USB_PRODUCT_DISPLAYLINK_NBDOCK },
        { USB_VENDOR_DISPLAYLINK, USB_PRODUCT_DISPLAYLINK_SWDVI },
        { USB_VENDOR_DISPLAYLINK, USB_PRODUCT_DISPLAYLINK_LUM70 },
        { USB_VENDOR_DISPLAYLINK, USB_PRODUCT_DISPLAYLINK_LCD8000UD_DVI },
        { USB_VENDOR_DISPLAYLINK, USB_PRODUCT_DISPLAYLINK_LDEWX015U },
        { USB_VENDOR_DISPLAYLINK, USB_PRODUCT_DISPLAYLINK_KC002N },
        { USB_VENDOR_DISPLAYLINK, USB_PRODUCT_DISPLAYLINK_MIMO },
        { USB_VENDOR_DISPLAYLINK, USB_PRODUCT_DISPLAYLINK_PLUGABLE },
        { USB_VENDOR_DISPLAYLINK, USB_PRODUCT_DISPLAYLINK_LT1421WIDE },
        { USB_VENDOR_DISPLAYLINK, USB_PRODUCT_DISPLAYLINK_SD_U2VDH },
        { USB_VENDOR_DISPLAYLINK, USB_PRODUCT_DISPLAYLINK_UM7X0 },
        { USB_VENDOR_DISPLAYLINK, USB_PRODUCT_DISPLAYLINK_FYDVI },
        { USB_VENDOR_DISPLAYLINK, USB_PRODUCT_DISPLAYLINK_FYDVI2 }
};

static int
udl_match(device_t parent, cfdata_t match, void *aux)
{
        struct usb_attach_arg *uaa = aux;

        if (usb_lookup(udl_devs, uaa->uaa_vendor, uaa->uaa_product) != NULL)
                return UMATCH_VENDOR_PRODUCT;

        return UMATCH_NONE;
}

static void
udl_attach(device_t parent, device_t self, void *aux)
{
        struct udl_softc *sc = device_private(self);
        struct usb_attach_arg *uaa = aux;
        struct wsemuldisplaydev_attach_args aa;
        const struct videomode *vmp;
        usbd_status error;
        char *devinfop;

        aprint_naive("\n");
        aprint_normal("\n");

        sc->sc_dev = self;
        sc->sc_udev = uaa->uaa_device;
        sc->sc_init_state = UDL_INIT_NONE;

        devinfop = usbd_devinfo_alloc(sc->sc_udev, 0);
        aprint_normal_dev(sc->sc_dev, "%s\n", devinfop);
        usbd_devinfo_free(devinfop);

        /*
         * Set device configuration descriptor number.
         */
        error = usbd_set_config_no(sc->sc_udev, 1, 0);
        if (error != USBD_NORMAL_COMPLETION) {
                aprint_error_dev(self, "failed to set configuration"
                    ", err=%s\n", usbd_errstr(error));
                return;
        }

        /*
         * Create device handle to interface descriptor.
         */
        error = usbd_device2interface_handle(sc->sc_udev, 0, &sc->sc_iface);
        if (error != USBD_NORMAL_COMPLETION)
                return;

        /*
         * Open bulk TX pipe.
         */
        error = usbd_open_pipe(sc->sc_iface, 1, USBD_EXCLUSIVE_USE,
            &sc->sc_tx_pipeh);
        if (error != USBD_NORMAL_COMPLETION)
                return;

#ifdef UDL_EVENT_COUNTERS
        evcnt_attach_dynamic(&sc->sc_ev_cmdq_get, EVCNT_TYPE_MISC, NULL,
            device_xname(sc->sc_dev), "udl_cmdq_get");
        evcnt_attach_dynamic(&sc->sc_ev_cmdq_put, EVCNT_TYPE_MISC, NULL,
            device_xname(sc->sc_dev), "udl_cmdq_put");
        evcnt_attach_dynamic(&sc->sc_ev_cmdq_wait, EVCNT_TYPE_MISC, NULL,
            device_xname(sc->sc_dev), "udl_cmdq_wait");
        evcnt_attach_dynamic(&sc->sc_ev_cmdq_timeout, EVCNT_TYPE_MISC, NULL,
            device_xname(sc->sc_dev), "udl_cmdq_timeout");
#endif
        cv_init(&sc->sc_cv, device_xname(sc->sc_dev));
        mutex_init(&sc->sc_mtx, MUTEX_DEFAULT, IPL_TTY); /* XXX for tty_lock */
        sc->sc_init_state = UDL_INIT_MIDWAY;

        /*
         * Allocate bulk command queue.
         */
        if (udl_cmdq_alloc(sc) != 0)
                return;

        if ((sc->sc_cmd_cur = udl_cmdq_get(sc)) == NULL)
                return;
        UDL_CMD_BUFINIT(sc);

        /*
         * Initialize chip.
         */
        if (udl_init(sc) != 0)
                return;

        udl_read_edid(sc);

        /*
         * Initialize resolution.
         */
#ifndef UDL_VIDEOMODE
        if (sc->sc_ei.edid_nmodes != 0 &&
            sc->sc_ei.edid_preferred_mode != NULL)
                vmp = sc->sc_ei.edid_preferred_mode;
        else
#define UDL_VIDEOMODE   "640x480x60"
#endif
                vmp = udl_videomode_lookup(UDL_VIDEOMODE);

        if (vmp == NULL)
                return;

        sc->sc_width = vmp->hdisplay;
        sc->sc_height = vmp->vdisplay;
        sc->sc_offscreen = sc->sc_height * 3 / 2;
        sc->sc_depth = 16;

        if (udl_set_resolution(sc, vmp) != 0)
                return;

        sc->sc_defaultscreen.name = "default";
        sc->sc_screens[0] = &sc->sc_defaultscreen;
        sc->sc_screenlist.nscreens = 1;
        sc->sc_screenlist.screens = sc->sc_screens;

        /*
         * Set initial wsdisplay emulation mode.
         */
        sc->sc_mode = WSDISPLAYIO_MODE_EMUL;

        /*
         * Attach wsdisplay.
         */
        aa.console = 0;
        aa.scrdata = &sc->sc_screenlist;
        aa.accessops = &udl_accessops;
        aa.accesscookie = sc;

        sc->sc_wsdisplay =
            config_found(sc->sc_dev, &aa, wsemuldisplaydevprint, CFARGS_NONE);

        usbd_add_drv_event(USB_EVENT_DRIVER_ATTACH, sc->sc_udev, sc->sc_dev);

        mutex_init(&sc->sc_thread_mtx, MUTEX_DEFAULT, IPL_NONE);
        cv_init(&sc->sc_thread_cv, "udlcv");
        sc->sc_dying = false;
        sc->sc_thread_stop = true;
        kthread_create(PRI_BIO, KTHREAD_MPSAFE | KTHREAD_MUSTJOIN, NULL,
            udl_update_thread, sc, &sc->sc_thread, "udlupd");

        sc->sc_init_state = UDL_INIT_INITED;
}

static int
udl_detach(device_t self, int flags)
{
        struct udl_softc *sc = device_private(self);

        /*
         * Close bulk TX pipe.
         */
        if (sc->sc_tx_pipeh != NULL) {
                usbd_abort_pipe(sc->sc_tx_pipeh);
        }

        if (sc->sc_init_state >= UDL_INIT_MIDWAY) {
                /*
                 * Free command xfer buffers.
                 */
                udl_cmdq_flush(sc);
                udl_cmdq_free(sc);
        }

        if (sc->sc_tx_pipeh != NULL) {
                usbd_close_pipe(sc->sc_tx_pipeh);
        }

        /*
         * Free Huffman table.
         */
        udl_comp_unload(sc);

        if (sc->sc_init_state >= UDL_INIT_INITED) {
                /*
                 * Free framebuffer memory.
                 */
                udl_fbmem_free(sc);

                mutex_enter(&sc->sc_thread_mtx);
                sc->sc_dying = true;
                cv_broadcast(&sc->sc_thread_cv);
                mutex_exit(&sc->sc_thread_mtx);
                kthread_join(sc->sc_thread);
                cv_destroy(&sc->sc_thread_cv);
                mutex_destroy(&sc->sc_thread_mtx);
        }

        if (sc->sc_init_state >= UDL_INIT_MIDWAY) {
                cv_destroy(&sc->sc_cv);
                mutex_destroy(&sc->sc_mtx);
        }

        if (sc->sc_init_state >= UDL_INIT_INITED) {
                /*
                 * Detach wsdisplay.
                 */
                if (sc->sc_wsdisplay != NULL)
                        config_detach(sc->sc_wsdisplay, DETACH_FORCE);

                usbd_add_drv_event(USB_EVENT_DRIVER_DETACH, sc->sc_udev,
                    sc->sc_dev);
        }

        if (sc->sc_init_state >= UDL_INIT_MIDWAY) {
#ifdef UDL_EVENT_COUNTERS
                evcnt_detach(&sc->sc_ev_cmdq_get);
                evcnt_detach(&sc->sc_ev_cmdq_put);
                evcnt_detach(&sc->sc_ev_cmdq_wait);
                evcnt_detach(&sc->sc_ev_cmdq_timeout);
#endif
        }

        return 0;
}

static int
udl_ioctl(void *v, void *vs, u_long cmd, void *data, int flag, struct lwp *l)
{
        struct udl_softc *sc = v;
#ifdef notyet
        struct udl_ioctl_damage *d;
#endif
        struct wsdisplay_fbinfo *wdf;
        u_int mode;

        switch (cmd) {
        case WSDISPLAYIO_GTYPE:
                *(u_int *)data = WSDISPLAY_TYPE_DL;
                return 0;

        case WSDISPLAYIO_GINFO:
                wdf = (struct wsdisplay_fbinfo *)data;
                wdf->height = sc->sc_height;
                wdf->width = sc->sc_width;
                wdf->depth = sc->sc_depth;
                wdf->cmsize = 0;
                return 0;

        case WSDISPLAYIO_GVIDEO:
                *(u_int *)data = sc->sc_blank;
                return 0;

        case WSDISPLAYIO_SVIDEO:
                mode = *(u_int *)data;
                if (mode == sc->sc_blank)
                        return 0;
                switch (mode) {
                case WSDISPLAYIO_VIDEO_OFF:
                        udl_startstop(sc, true);
                        udl_blank(sc, 1);
                        break;
                case WSDISPLAYIO_VIDEO_ON:
                        udl_blank(sc, 0);
                        break;
                default:
                        return EINVAL;
                }
                if (UDL_CMD_BUFSIZE(sc) > 0)
                        udl_cmd_send_async(sc);
                udl_cmdq_flush(sc);
                sc->sc_blank = mode;
                return 0;

        case WSDISPLAYIO_SMODE:
                mode = *(u_int *)data;
                if (mode == sc->sc_mode)
                        return 0;
                switch (mode) {
                case WSDISPLAYIO_MODE_EMUL:
                        udl_startstop(sc, true);
                        /* clear screen */
                        udl_fill_rect(sc, 0, 0, 0, sc->sc_width,
                            sc->sc_height);
                        if (UDL_CMD_BUFSIZE(sc) > 0)
                                udl_cmd_send_async(sc);
                        udl_cmdq_flush(sc);
                        udl_comp_unload(sc);
                        break;
                case WSDISPLAYIO_MODE_DUMBFB:
                        if (UDL_CMD_BUFSIZE(sc) > 0)
                                udl_cmd_send_async(sc);
                        udl_cmdq_flush(sc);
                        udl_comp_load(sc);
                        udl_startstop(sc, false);
                        break;
                default:
                        return EINVAL;
                }
                sc->sc_mode = mode;
                return 0;

        case WSDISPLAYIO_LINEBYTES:
                *(u_int *)data = sc->sc_width * (sc->sc_depth / 8);
                return 0;

#ifdef notyet
        /*
         * XXX
         * OpenBSD allows device specific ioctl()s and use this
         * UDLIO_DAMAGE for the damage extension ops of X servers.
         * Before blindly pulling such interfaces, probably we should
         * discuss how such devices should be handled which have
         * in-direct framebuffer memories that should be transferred
         * per updated rectangle regions via MI wscons APIs.
         */
        case UDLIO_DAMAGE:
                d = (struct udl_ioctl_damage *)data;
                d->status = UDLIO_STATUS_OK;
                if (sc->sc_flags & UDL_COMPRDY)
                        udl_draw_rect_comp(sc, d);
                else
                        udl_draw_rect(sc, d);
                return 0;
#endif
        }

        return EPASSTHROUGH;
}

static paddr_t
udl_mmap(void *v, void *vs, off_t off, int prot)
{
        struct udl_softc *sc = v;
        vaddr_t vaddr;
        paddr_t paddr;
        bool rv __diagused;

        if (off < 0 || off > roundup2(UDL_FBMEM_SIZE(sc), PAGE_SIZE))
                return -1;

        /* allocate framebuffer memory */
        if (udl_fbmem_alloc(sc) != 0)
                return -1;

        udl_startstop(sc, false);

        vaddr = (vaddr_t)sc->sc_fbmem + off;
        rv = pmap_extract(pmap_kernel(), vaddr, &paddr);
        KASSERT(rv);
        paddr += vaddr & PGOFSET;

        /* XXX we need MI paddr_t -> mmap cookie API */
#if defined(__aarch64__)
#define PTOMMAP(paddr)  aarch64_btop((char *)paddr)
#elif defined(__alpha__)
#define PTOMMAP(paddr)  alpha_btop((char *)paddr)
#elif defined(__arm__)
#define PTOMMAP(paddr)  arm_btop((u_long)paddr)
#elif defined(__hppa__)
#define PTOMMAP(paddr)  btop((u_long)paddr)
#elif defined(__i386__) || defined(__x86_64__)
#define PTOMMAP(paddr)  x86_btop(paddr)
#elif defined(__m68k__)
#define PTOMMAP(paddr)  m68k_btop((char *)paddr)
#elif defined(__mips__)
#define PTOMMAP(paddr)  mips_btop(paddr)
#elif defined(__powerpc__)
#define PTOMMAP(paddr)  (paddr)
#elif defined(__riscv__)
#define PTOMMAP(paddr)  riscv_btop(paddr)
#elif defined(__sh__)
#define PTOMMAP(paddr)  sh3_btop(paddr)
#elif defined(__sparc__)
#define PTOMMAP(paddr)  (paddr)
#elif defined(__sparc64__)
#define PTOMMAP(paddr)  atop(paddr)
#elif defined(__vax__)
#define PTOMMAP(paddr)  btop((u_int)paddr)
#endif

        return PTOMMAP(paddr);
}

static int
udl_alloc_screen(void *v, const struct wsscreen_descr *type,
    void **cookiep, int *curxp, int *curyp, long *attrp)
{
        struct udl_softc *sc = v;

        if (sc->sc_nscreens > 0)
                return ENOMEM;

        /*
         * Initialize rasops.
         */
        sc->sc_ri.ri_depth = sc->sc_depth;
        sc->sc_ri.ri_bits = NULL;
        sc->sc_ri.ri_width = sc->sc_width;
        sc->sc_ri.ri_height = sc->sc_height;
        sc->sc_ri.ri_stride = sc->sc_width * (sc->sc_depth / 8);
        sc->sc_ri.ri_hw = sc;
        sc->sc_ri.ri_flg = 0;

        if (sc->sc_depth == 16) {
                sc->sc_ri.ri_rnum = 5;
                sc->sc_ri.ri_gnum = 6;
                sc->sc_ri.ri_bnum = 5;
                sc->sc_ri.ri_rpos = 11;
                sc->sc_ri.ri_gpos = 5;
                sc->sc_ri.ri_bpos = 0;
        }

        rasops_init(&sc->sc_ri, sc->sc_height / 8, sc->sc_width / 8);

        sc->sc_ri.ri_ops.cursor = udl_cursor;
        sc->sc_ri.ri_ops.putchar = udl_putchar;
        sc->sc_ri.ri_ops.copycols = udl_copycols;
        sc->sc_ri.ri_ops.erasecols = udl_erasecols;
        sc->sc_ri.ri_ops.copyrows = udl_copyrows;
        sc->sc_ri.ri_ops.eraserows = udl_eraserows;

        sc->sc_ri.ri_ops.allocattr(&sc->sc_ri, 0, 0, 0, attrp);

        sc->sc_defaultscreen.ncols = sc->sc_ri.ri_cols;
        sc->sc_defaultscreen.nrows = sc->sc_ri.ri_rows;
        sc->sc_defaultscreen.textops = &sc->sc_ri.ri_ops;
        sc->sc_defaultscreen.fontwidth = sc->sc_ri.ri_font->fontwidth;
        sc->sc_defaultscreen.fontheight = sc->sc_ri.ri_font->fontheight;
        sc->sc_defaultscreen.capabilities = sc->sc_ri.ri_caps;

        *cookiep = &sc->sc_ri;
        *curxp = 0;
        *curyp = 0;

        sc->sc_nscreens++;

        return 0;
}

static void
udl_free_screen(void *v, void *cookie)
{
        struct udl_softc *sc = v;

        sc->sc_nscreens--;
}

static int
udl_show_screen(void *v, void *cookie, int waitok,
    void (*cb)(void *, int, int), void *cbarg)
{

        return 0;
}

static inline void
udl_cmd_add_decomptable(struct udl_softc *sc, uint8_t *buf, int len)
{

        udl_cmd_add_2(sc, (UDL_BULK_SOC << 8) | UDL_BULK_CMD_DECOMP);
        udl_cmd_add_4(sc, 0x263871cd);  /* magic number */
        udl_cmd_add_4(sc, 0x00000200);  /* 512 byte chunks */
        memcpy(sc->sc_cmd_buf, buf, len);
        sc->sc_cmd_buf += len;
}

static void
udl_comp_load(struct udl_softc *sc)
{
        struct udl_huffman *h;
        uint8_t *decomp;
        size_t decomp_size;
        int error, i;

        if (!(sc->sc_flags & UDL_DECOMPRDY)) {
                error = firmware_load("udl", "udl-decomp", &decomp,
                    &decomp_size);
                if (error != 0) {
                        aprint_error_dev(sc->sc_dev,
                            "error %d, could not read decomp table %s!\n",
                            error, "udl-decomp");
                        return;
                }
                udl_cmd_add_decomptable(sc, decomp, decomp_size);
                firmware_free(decomp, decomp_size);
                if (udl_cmd_send(sc) != 0)
                        return;
                sc->sc_flags |= UDL_DECOMPRDY;
        }

        if (!(sc->sc_flags & UDL_COMPRDY)) {
                error = firmware_load("udl", "udl-comp", &sc->sc_huffman,
                    &sc->sc_huffman_size);
                if (error != 0) {
                        aprint_error_dev(sc->sc_dev,
                            "error %d, could not read huffman table %s!\n",
                            error, "udl-comp");
                        return;
                }
                h = (struct udl_huffman *)sc->sc_huffman;
                for (i = 0; i < UDL_HUFFMAN_RECORDS; i++)
                        h[i].bit_pattern = be32toh(h[i].bit_pattern);
                sc->sc_huffman_base = sc->sc_huffman + UDL_HUFFMAN_BASE;
                sc->sc_flags |= UDL_COMPRDY;
        }
}

static void
udl_comp_unload(struct udl_softc *sc)
{

        if (sc->sc_flags & UDL_COMPRDY) {
                firmware_free(sc->sc_huffman, sc->sc_huffman_size);
                sc->sc_huffman = NULL;
                sc->sc_huffman_size = 0;
                sc->sc_flags &= ~UDL_COMPRDY;
        }
}

static int
udl_fbmem_alloc(struct udl_softc *sc)
{

        mutex_enter(&sc->sc_thread_mtx);
        if (sc->sc_fbmem == NULL)
                sc->sc_fbmem = kmem_zalloc(UDL_FBMEM_SIZE(sc), KM_SLEEP);
        if (sc->sc_fbmem_prev == NULL)
                sc->sc_fbmem_prev = kmem_zalloc(UDL_FBMEM_SIZE(sc), KM_SLEEP);
        mutex_exit(&sc->sc_thread_mtx);

        return 0;
}

static void
udl_fbmem_free(struct udl_softc *sc)
{

        mutex_enter(&sc->sc_thread_mtx);
        if (sc->sc_fbmem != NULL) {
                kmem_free(sc->sc_fbmem, UDL_FBMEM_SIZE(sc));
                sc->sc_fbmem = NULL;
        }
        if (sc->sc_fbmem_prev != NULL) {
                kmem_free(sc->sc_fbmem_prev, UDL_FBMEM_SIZE(sc));
                sc->sc_fbmem_prev = NULL;
        }
        mutex_exit(&sc->sc_thread_mtx);
}

static int
udl_cmdq_alloc(struct udl_softc *sc)
{
        struct udl_cmdq *cmdq;
        int i;

        TAILQ_INIT(&sc->sc_freecmd);
        TAILQ_INIT(&sc->sc_xfercmd);

        for (i = 0; i < UDL_NCMDQ; i++) {
                cmdq = &sc->sc_cmdq[i];

                cmdq->cq_sc = sc;

                int err = usbd_create_xfer(sc->sc_tx_pipeh,
                    UDL_CMD_BUFFER_SIZE, 0, 0, &cmdq->cq_xfer);
                if (err) {
                        aprint_error_dev(sc->sc_dev,
                            "%s: can't allocate xfer handle!\n", __func__);
                        goto error;
                }

                cmdq->cq_buf = usbd_get_buffer(cmdq->cq_xfer);

                TAILQ_INSERT_TAIL(&sc->sc_freecmd, cmdq, cq_chain);
        }

        return 0;

 error:
        udl_cmdq_free(sc);
        return -1;
}

static void
udl_cmdq_free(struct udl_softc *sc)
{
        struct udl_cmdq *cmdq;
        int i;

        for (i = 0; i < UDL_NCMDQ; i++) {
                cmdq = &sc->sc_cmdq[i];

                if (cmdq->cq_xfer != NULL) {
                        usbd_destroy_xfer(cmdq->cq_xfer);
                        cmdq->cq_xfer = NULL;
                        cmdq->cq_buf = NULL;
                }
        }
}

static struct udl_cmdq *
udl_cmdq_get(struct udl_softc *sc)
{
        struct udl_cmdq *cmdq;

        cmdq = TAILQ_FIRST(&sc->sc_freecmd);
        if (cmdq != NULL) {
                TAILQ_REMOVE(&sc->sc_freecmd, cmdq, cq_chain);
                UDL_EVCNT_INCR(&sc->sc_ev_cmdq_get);
        }

        return cmdq;
}

static void
udl_cmdq_put(struct udl_softc *sc, struct udl_cmdq *cmdq)
{

        TAILQ_INSERT_TAIL(&sc->sc_freecmd, cmdq, cq_chain);
        UDL_EVCNT_INCR(&sc->sc_ev_cmdq_put);
}

static void
udl_cmdq_flush(struct udl_softc *sc)
{

        mutex_enter(&sc->sc_mtx);
        while (TAILQ_FIRST(&sc->sc_xfercmd) != NULL)
                cv_wait(&sc->sc_cv, &sc->sc_mtx);
        mutex_exit(&sc->sc_mtx);
}

static void
udl_cursor(void *cookie, int on, int row, int col)
{
        struct rasops_info *ri = cookie;
        struct udl_softc *sc = ri->ri_hw;
        int x, y, width, height;

        if (ri->ri_flg & RI_CURSOR)
                udl_restore_char(ri);

        ri->ri_crow = row;
        ri->ri_ccol = col;

        if (on != 0) {
                ri->ri_flg |= RI_CURSOR;

                x = col * ri->ri_font->fontwidth;
                y = row * ri->ri_font->fontheight;
                width = ri->ri_font->fontwidth;
                height = ri->ri_font->fontheight;

                /* save the last character block to off-screen */
                udl_copy_rect(sc, x, y, 0, sc->sc_offscreen, width, height);

                /* draw cursor */
                udl_fill_rect(sc, 0xffff, x, y, width, 1);
                udl_fill_rect(sc, 0xffff, x, y + 1, 1, height - 2);
                udl_fill_rect(sc, 0xffff, x + width - 1, y + 1, 1, height - 2);
                udl_fill_rect(sc, 0xffff, x, y + height - 1, width, 1);

                udl_cmd_send_async(sc);
        } else
                ri->ri_flg &= ~RI_CURSOR;
}

static void
udl_putchar(void *cookie, int row, int col, u_int uc, long attr)
{
        struct rasops_info *ri = cookie;
        struct udl_softc *sc = ri->ri_hw;
        uint16_t rgb16[2];
        int fg, bg, underline, x, y, width, height;

        rasops_unpack_attr(attr, &fg, &bg, &underline);
        rgb16[1] = (uint16_t)ri->ri_devcmap[fg];
        rgb16[0] = (uint16_t)ri->ri_devcmap[bg];

        x = col * ri->ri_font->fontwidth;
        y = row * ri->ri_font->fontheight;
        width = ri->ri_font->fontwidth;
        height = ri->ri_font->fontheight;

        if (uc == ' ') {
                /*
                 * Writing a block for the space character instead rendering
                 * it from font bits is more slim.
                 */
                udl_fill_rect(sc, rgb16[0], x, y, width, height);
        } else {
                /* render a character from font bits */
                udl_draw_char(ri, rgb16, uc, x, y);
        }

        if (underline != 0)
                udl_fill_rect(sc, rgb16[1], x, y + height - 1, width, 1);

#if 0
        udl_cmd_send_async(sc);
#endif
}

static void
udl_copycols(void *cookie, int row, int src, int dst, int num)
{
        struct rasops_info *ri = cookie;
        struct udl_softc *sc = ri->ri_hw;
        int sx, dx, y, width, height;

        sx = src * ri->ri_font->fontwidth;
        dx = dst * ri->ri_font->fontwidth;
        y = row * ri->ri_font->fontheight;
        width = num * ri->ri_font->fontwidth;
        height = ri->ri_font->fontheight;

        /* copy row block to off-screen first to fix overlay-copy problem */
        udl_copy_rect(sc, sx, y, 0, sc->sc_offscreen, width, height);

        /* copy row block back from off-screen now */
        udl_copy_rect(sc, 0, sc->sc_offscreen, dx, y, width, height);
#if 0
        udl_cmd_send_async(sc);
#endif
}

static void
udl_erasecols(void *cookie, int row, int col, int num, long attr)
{
        struct rasops_info *ri = cookie;
        struct udl_softc *sc = ri->ri_hw;
        uint16_t rgb16;
        int fg, bg, x, y, width, height;

        rasops_unpack_attr(attr, &fg, &bg, NULL);
        rgb16 = (uint16_t)ri->ri_devcmap[bg];

        x = col * ri->ri_font->fontwidth;
        y = row * ri->ri_font->fontheight;
        width = num * ri->ri_font->fontwidth;
        height = ri->ri_font->fontheight;

        udl_fill_rect(sc, rgb16, x, y, width, height);
#if 0
        udl_cmd_send_async(sc);
#endif
}

static void
udl_copyrows(void *cookie, int src, int dst, int num)
{
        struct rasops_info *ri = cookie;
        struct udl_softc *sc = ri->ri_hw;
        int sy, ey, dy, width, height;

        width = ri->ri_emuwidth;
        height = ri->ri_font->fontheight;

        if (dst < src) {
                sy = src * height;
                ey = (src + num) * height;
                dy = dst * height;

                while (sy < ey) {
                        udl_copy_rect(sc, 0, sy, 0, dy, width, height);
                        sy += height;
                        dy += height;
                }
        } else {
                sy = (src + num) * height;
                ey = src * height;
                dy = (dst + num) * height;

                while (sy > ey) {
                        sy -= height;
                        dy -= height;
                        udl_copy_rect(sc, 0, sy, 0, dy, width, height);
                }
        }
#if 0
        udl_cmd_send_async(sc);
#endif
}

static void
udl_eraserows(void *cookie, int row, int num, long attr)
{
        struct rasops_info *ri = cookie;
        struct udl_softc *sc = ri->ri_hw;
        uint16_t rgb16;
        int fg, bg, y, width, height;

        rasops_unpack_attr(attr, &fg, &bg, NULL);
        rgb16 = (uint16_t)ri->ri_devcmap[bg];

        y = row * ri->ri_font->fontheight;
        width = ri->ri_emuwidth;
        height = num * ri->ri_font->fontheight;

        udl_fill_rect(sc, rgb16, 0, y, width, height);
#if 0
        udl_cmd_send_async(sc);
#endif
}

static void
udl_restore_char(struct rasops_info *ri)
{
        struct udl_softc *sc = ri->ri_hw;
        int x, y, width, height;

        x = ri->ri_ccol * ri->ri_font->fontwidth;
        y = ri->ri_crow * ri->ri_font->fontheight;
        width = ri->ri_font->fontwidth;
        height = ri->ri_font->fontheight;

        /* restore the last saved character from off-screen */
        udl_copy_rect(sc, 0, sc->sc_offscreen, x, y, width, height);
}

static void
udl_draw_char(struct rasops_info *ri, uint16_t *rgb16, u_int uc, int x, int y)
{
        struct udl_softc *sc = ri->ri_hw;
        struct wsdisplay_font *font = ri->ri_font;
        uint32_t fontbits;
        uint16_t pixels[32];
        uint8_t *fontbase;
        int i, soff, eoff;

        soff = y * sc->sc_width + x;
        eoff = (y + font->fontheight) * sc->sc_width + x;
        fontbase = (uint8_t *)font->data + (uc - font->firstchar) *
            ri->ri_fontscale;

        while (soff < eoff) {
                fontbits = 0;
                switch (font->stride) {
                case 4:
                        fontbits |= fontbase[3];
                        /* FALLTHROUGH */
                case 3:
                        fontbits |= fontbase[2] << 8;
                        /* FALLTHROUGH */
                case 2:
                        fontbits |= fontbase[1] << 16;
                        /* FALLTHROUGH */
                case 1:
                        fontbits |= fontbase[0] << 24;
                }
                fontbase += font->stride;

                for (i = 0; i < font->fontwidth; i++) {
                        pixels[i] = rgb16[(fontbits >> 31) & 1];
                        fontbits <<= 1;
                }

                udl_draw_line(sc, pixels, soff, font->fontwidth);
                soff += sc->sc_width;
        }
}

static void
udl_copy_rect(struct udl_softc *sc, int sx, int sy, int dx, int dy, int width,
    int height)
{
        int sbase, soff, ebase, eoff, dbase, doff, width_cur;

        sbase = sy * sc->sc_width;
        ebase = (sy + height) * sc->sc_width;
        dbase = dy * sc->sc_width;

        while (width > 0) {
                soff = sbase + sx;
                eoff = ebase + sx;
                doff = dbase + dx;

                if (width >= UDL_CMD_WIDTH_MAX)
                        width_cur = UDL_CMD_WIDTH_MAX;
                else
                        width_cur = width;

                while (soff < eoff) {
                        udl_copy_line(sc, soff, doff, width_cur);
                        soff += sc->sc_width;
                        doff += sc->sc_width;
                }

                sx += width_cur;
                dx += width_cur;
                width -= width_cur;
        }
}

static void
udl_fill_rect(struct udl_softc *sc, uint16_t rgb16, int x, int y, int width,
    int height)
{
        int sbase, soff, ebase, eoff, width_cur;

        sbase = y * sc->sc_width;
        ebase = (y + height) * sc->sc_width;

        while (width > 0) {
                soff = sbase + x;
                eoff = ebase + x;

                if (width >= UDL_CMD_WIDTH_MAX)
                        width_cur = UDL_CMD_WIDTH_MAX;
                else
                        width_cur = width;

                while (soff < eoff) {
                        udl_fill_line(sc, rgb16, soff, width_cur);
                        soff += sc->sc_width;
                }

                x += width_cur;
                width -= width_cur;
        }
}

#ifdef notyet
static void
udl_draw_rect(struct udl_softc *sc, struct udl_ioctl_damage *d)
{
        int sbase, soff, ebase, eoff, x, y, width, width_cur, height;

        x = d->x1;
        y = d->y1;
        width = d->x2 - d->x1;
        height = d->y2 - d->y1;
        sbase = y * sc->sc_width;
        ebase = (y + height) * sc->sc_width;

        while (width > 0) {
                soff = sbase + x;
                eoff = ebase + x;

                if (width >= UDL_CMD_WIDTH_MAX)
                        width_cur = UDL_CMD_WIDTH_MAX;
                else
                        width_cur = width;

                while (soff < eoff) {
                        udl_draw_line(sc, (uint16_t *)sc->sc_fbmem + soff,
                            soff, width_cur);
                        soff += sc->sc_width;
                }

                x += width_cur;
                width -= width_cur;
        }

        udl_cmd_send_async(sc);
}

static void
udl_draw_rect_comp(struct udl_softc *sc, struct udl_ioctl_damage *d)
{
        int soff, eoff, x, y, width, height;

        x = d->x1;
        y = d->y1;
        width = d->x2 - d->x1;
        height = d->y2 - d->y1;
        soff = y * sc->sc_width + x;
        eoff = (y + height) * sc->sc_width + x;

        udl_reg_write_1(sc, UDL_REG_SYNC, 0xff);
        sc->sc_cmd_cblen = 4;

        while (soff < eoff) {
                udl_draw_line_comp(sc, (uint16_t *)sc->sc_fbmem + soff, soff,
                    width);
                soff += sc->sc_width;
        }

        udl_cmd_send_async(sc);
}
#endif

static inline void
udl_copy_line(struct udl_softc *sc, int soff, int doff, int width)
{

        if (__predict_false((UDL_CMD_BUFSIZE(sc) + UDL_CMD_COPY_SIZE + 2) >
            UDL_CMD_BUFFER_SIZE))
                udl_cmd_send_async(sc);

        udl_cmd_add_2(sc, (UDL_BULK_SOC << 8) | UDL_BULK_CMD_FB_COPY16);
        udl_cmd_add_4(sc, ((doff * 2) << 8) | (width & 0xff));

        udl_cmd_add_3(sc, soff * 2);
}

static inline void
udl_fill_line(struct udl_softc *sc, uint16_t rgb16, int off, int width)
{

        if (__predict_false((UDL_CMD_BUFSIZE(sc) + UDL_CMD_FILL_SIZE + 2) >
            UDL_CMD_BUFFER_SIZE))
                udl_cmd_send_async(sc);

        udl_cmd_add_2(sc, (UDL_BULK_SOC << 8) | UDL_BULK_CMD_FB_RLE16);
        udl_cmd_add_4(sc, ((off * 2) << 8) | (width & 0xff));

        udl_cmd_add_1(sc, width);
        udl_cmd_add_2(sc, rgb16);
}

static inline void
udl_draw_line(struct udl_softc *sc, uint16_t *buf, int off, int width)
{

        if (__predict_false(
            (UDL_CMD_BUFSIZE(sc) + UDL_CMD_DRAW_SIZE(width) + 2) >
            UDL_CMD_BUFFER_SIZE))
                udl_cmd_send_async(sc);

        udl_cmd_add_2(sc, (UDL_BULK_SOC << 8) | UDL_BULK_CMD_FB_WRITE16);
        udl_cmd_add_4(sc, ((off * 2) << 8) | (width & 0xff));

        udl_cmd_add_buf(sc, buf, width);
}

#ifdef notyet
static inline int
udl_cmd_add_buf_comp(struct udl_softc *sc, uint16_t *buf, int width)
{
        struct udl_huffman *h;
        uint16_t *startp, *endp;
        uint32_t bit_pattern;
        uint16_t prev;
        int16_t diff;
        uint8_t bit_count, bit_pos, bit_rem, curlen;

        startp = buf;
        if (width >= UDL_CMD_WIDTH_MAX)
                endp = buf + UDL_CMD_WIDTH_MAX;
        else
                endp = buf + width;

        prev = bit_pos = *sc->sc_cmd_buf = 0;
        bit_rem = 8;

        /*
         * Generate a sub-block with maximal 256 pixels compressed data.
         */
        while (buf < endp) {
                /* get difference between current and previous pixel */
                diff = *buf - prev;

                /* get the huffman difference bit sequence */
                h = (struct udl_huffman *)sc->sc_huffman_base + diff;
                bit_count = h->bit_count;
                bit_pattern = h->bit_pattern;

                curlen = (bit_pos + bit_count + 7) / 8;
                if (__predict_false((sc->sc_cmd_cblen + curlen + 1) >
                    UDL_CMD_COMP_BLOCK_SIZE))
                        break;

                /* generate one pixel compressed data */
                while (bit_count >= bit_rem) {
                        *sc->sc_cmd_buf++ |=
                            (bit_pattern & ((1 << bit_rem) - 1)) << bit_pos;
                        *sc->sc_cmd_buf = 0;
                        sc->sc_cmd_cblen++;
                        bit_count -= bit_rem;
                        bit_pattern >>= bit_rem;
                        bit_pos = 0;
                        bit_rem = 8;
                }

                if (bit_count > 0) {
                        *sc->sc_cmd_buf |=
                            (bit_pattern & ((1 << bit_count) - 1)) << bit_pos;
                        bit_pos += bit_count;
                        bit_rem -= bit_count;
                }

                prev = *buf++;
        }

        /*
         * If we have bits left in our last byte, round up to the next
         * byte, so we don't overwrite them.
         */
        if (bit_pos > 0) {
                sc->sc_cmd_buf++;
                sc->sc_cmd_cblen++;
        }

        /* return how many pixels we have compressed */
        return buf - startp;
}

static inline void
udl_draw_line_comp(struct udl_softc *sc, uint16_t *buf, int off, int width)
{
        uint8_t *widthp;
        int width_cur;

        while (width > 0) {
                if (__predict_false(
                    (sc->sc_cmd_cblen + UDL_CMD_COMP_MIN_SIZE + 1) >
                    UDL_CMD_COMP_BLOCK_SIZE)) {
                        if (UDL_CMD_BUFSIZE(sc) < UDL_CMD_COMP_THRESHOLD) {
                                while (sc->sc_cmd_cblen <
                                    UDL_CMD_COMP_BLOCK_SIZE) {
                                        *sc->sc_cmd_buf++ = 0;
                                        sc->sc_cmd_cblen++;
                                }
                        } else
                                udl_cmd_send_async(sc);
                        udl_reg_write_1(sc, UDL_REG_SYNC, 0xff);
                        sc->sc_cmd_cblen = 4;
                }

                udl_cmd_add_2(sc, (UDL_BULK_SOC << 8) |
                    (UDL_BULK_CMD_FB_WRITE16 | UDL_BULK_CMD_FB_COMP));
                udl_cmd_add_4(sc, (off * 2) << 8);

                widthp = sc->sc_cmd_buf - 1;

                sc->sc_cmd_cblen += UDL_CMD_HEADER_SIZE;

                width_cur = udl_cmd_add_buf_comp(sc, buf, width);

                *widthp = width_cur;
                buf += width_cur;
                off += width_cur;
                width -= width_cur;
        }
}
#endif

static int
udl_cmd_send(struct udl_softc *sc)
{
        struct udl_cmdq *cmdq;
        usbd_status error;
        uint32_t len;

        cmdq = sc->sc_cmd_cur;

        /* mark end of command stack */
        udl_cmd_add_2(sc, (UDL_BULK_SOC << 8) | UDL_BULK_CMD_EOC);

        len = UDL_CMD_BUFSIZE(sc);

        /* do xfer */
        error = usbd_bulk_transfer(cmdq->cq_xfer, sc->sc_tx_pipeh, 0,
            USBD_NO_TIMEOUT, cmdq->cq_buf, &len);

        UDL_CMD_BUFINIT(sc);

        if (error != USBD_NORMAL_COMPLETION) {
                aprint_error_dev(sc->sc_dev, "%s: %s!\n", __func__,
                    usbd_errstr(error));
                return -1;
        }

        return 0;
}

static void
udl_cmd_send_async(struct udl_softc *sc)
{
        struct udl_cmdq *cmdq;
        usbd_status error;
        uint32_t len;

#if 1
        /*
         * XXX
         * All tty ops for wsemul are called with tty_lock spin mutex held,
         * so we can't call cv_wait(9) here to acquire a free buffer.
         * For now, all commands and data for wsemul ops are discarded
         * if there is no free command buffer, and then screen text might
         * be corrupted on large scroll ops etc.
         *
         * Probably we have to reorganize the giant tty_lock mutex, or
         * change wsdisplay APIs (especially wsdisplaystart()) to return
         * a number of actually handled characters as OpenBSD does, but
         * the latter one requires whole API changes around rasops(9) etc.
         */
        if (sc->sc_mode == WSDISPLAYIO_MODE_EMUL) {
                if (TAILQ_FIRST(&sc->sc_freecmd) == NULL) {
                        UDL_CMD_BUFINIT(sc);
                        return;
                }
        }
#endif

        cmdq = sc->sc_cmd_cur;

        /* mark end of command stack */
        udl_cmd_add_2(sc, (UDL_BULK_SOC << 8) | UDL_BULK_CMD_EOC);

        len = UDL_CMD_BUFSIZE(sc);

        /* do xfer */
        mutex_enter(&sc->sc_mtx);
        usbd_setup_xfer(cmdq->cq_xfer, cmdq, cmdq->cq_buf,
            len, 0, USBD_NO_TIMEOUT, udl_cmd_send_async_cb);
        mutex_exit(&sc->sc_mtx);
        error = usbd_transfer(cmdq->cq_xfer);
        mutex_enter(&sc->sc_mtx);
        if (error != USBD_NORMAL_COMPLETION && error != USBD_IN_PROGRESS) {
                aprint_error_dev(sc->sc_dev, "%s: %s!\n", __func__,
                    usbd_errstr(error));
                mutex_exit(&sc->sc_mtx);
                goto end;
        }

        TAILQ_INSERT_TAIL(&sc->sc_xfercmd, cmdq, cq_chain);
        cmdq = udl_cmdq_get(sc);
        mutex_exit(&sc->sc_mtx);
        while (cmdq == NULL) {
                int err;
                UDL_EVCNT_INCR(&sc->sc_ev_cmdq_wait);
                mutex_enter(&sc->sc_mtx);
                err = cv_timedwait(&sc->sc_cv, &sc->sc_mtx,
                    mstohz(100) /* XXX is this needed? */);
                if (err != 0) {
                        DPRINTF(("%s: %s: cv timeout (error = %d)\n",
                            device_xname(sc->sc_dev), __func__, err));
                        UDL_EVCNT_INCR(&sc->sc_ev_cmdq_timeout);
                }
                cmdq = udl_cmdq_get(sc);
                mutex_exit(&sc->sc_mtx);
        }
        sc->sc_cmd_cur = cmdq;
 end:
        UDL_CMD_BUFINIT(sc);
}

static void
udl_cmd_send_async_cb(struct usbd_xfer *xfer, void * priv,
    usbd_status status)
{
        struct udl_cmdq *cmdq = priv;
        struct udl_softc *sc = cmdq->cq_sc;

        if (status != USBD_NORMAL_COMPLETION) {
                aprint_error_dev(sc->sc_dev, "%s: %s!\n", __func__,
                    usbd_errstr(status));

                if (status == USBD_NOT_STARTED || status == USBD_CANCELLED)
                        return;
                if (status == USBD_STALLED)
                        usbd_clear_endpoint_stall_async(sc->sc_tx_pipeh);
        }

        mutex_enter(&sc->sc_mtx);
        TAILQ_REMOVE(&sc->sc_xfercmd, cmdq, cq_chain);
        udl_cmdq_put(sc, cmdq);

        /* signal xfer op that sleeps for a free xfer buffer */
        cv_signal(&sc->sc_cv);
        mutex_exit(&sc->sc_mtx);
}

static int
udl_ctrl_msg(struct udl_softc *sc, uint8_t rt, uint8_t r, uint16_t index,
    uint16_t value, uint8_t *buf, uint16_t len)
{
        usb_device_request_t req;
        usbd_status error;

        req.bmRequestType = rt;
        req.bRequest = r;
        USETW(req.wIndex, index);
        USETW(req.wValue, value);
        USETW(req.wLength, len);

        error = usbd_do_request(sc->sc_udev, &req, buf);
        if (error != USBD_NORMAL_COMPLETION) {
                aprint_error_dev(sc->sc_dev, "%s: %s!\n", __func__,
                    usbd_errstr(error));
                return -1;
        }

        return 0;
}

static int
udl_init(struct udl_softc *sc)
{
        static uint8_t key[16] = {
            0x57, 0xcd, 0xdc, 0xa7, 0x1c, 0x88, 0x5e, 0x15,
            0x60, 0xfe, 0xc6, 0x97, 0x16, 0x3d, 0x47, 0xf2
        };
        uint8_t status[4], val;

        if (udl_ctrl_msg(sc, UT_READ_VENDOR_DEVICE, UDL_CTRL_CMD_READ_STATUS,
            0x0000, 0x0000, status, sizeof(status)) != 0)
                return -1;

        if (udl_ctrl_msg(sc, UT_READ_VENDOR_DEVICE, UDL_CTRL_CMD_READ_1,
            0xc484, 0x0000, &val, 1) != 0)
                return -1;

        val = 1;
        if (udl_ctrl_msg(sc, UT_WRITE_VENDOR_DEVICE, UDL_CTRL_CMD_WRITE_1,
            0xc41f, 0x0000, &val, 1) != 0)
                return -1;

        if (udl_ctrl_msg(sc, UT_WRITE_VENDOR_DEVICE, UDL_CTRL_CMD_SET_KEY,
            0x0000, 0x0000, key, sizeof(key)) != 0)
                return -1;

        val = 0;
        if (udl_ctrl_msg(sc, UT_WRITE_VENDOR_DEVICE, UDL_CTRL_CMD_WRITE_1,
            0xc40b, 0x0000, &val, 1) != 0)
                return -1;

        return 0;
}

static void
udl_read_edid(struct udl_softc *sc)
{
        uint8_t buf[64], edid[128];
        int offset;

        memset(&sc->sc_ei, 0, sizeof(struct edid_info));

        offset = 0;
        if (udl_ctrl_msg(sc, UT_READ_VENDOR_DEVICE, UDL_CTRL_CMD_READ_EDID,
            0x00a1, (offset << 8), buf, 64) != 0)
                return;
        if (buf[0] != 0)
                return;
        memcpy(&edid[offset], &buf[1], 63);
        offset += 63;

        if (udl_ctrl_msg(sc, UT_READ_VENDOR_DEVICE, UDL_CTRL_CMD_READ_EDID,
            0x00a1, (offset << 8), buf, 64) != 0)
                return;
        if (buf[0] != 0)
                return;
        memcpy(&edid[offset], &buf[1], 63);
        offset += 63;

        if (udl_ctrl_msg(sc, UT_READ_VENDOR_DEVICE, UDL_CTRL_CMD_READ_EDID,
            0x00a1, (offset << 8), buf, 3) != 0)
                return;
        if (buf[0] != 0)
                return;
        memcpy(&edid[offset], &buf[1], 2);

        if (edid_parse(edid, &sc->sc_ei) == 0) {
#ifdef UDL_DEBUG
                edid_print(&sc->sc_ei);
#endif
        }
}

static void
udl_set_address(struct udl_softc *sc, int start16, int stride16, int start8,
    int stride8)
{
        udl_reg_write_1(sc, UDL_REG_SYNC, 0x00);
        udl_reg_write_3(sc, UDL_REG_ADDR_START16, start16);
        udl_reg_write_3(sc, UDL_REG_ADDR_STRIDE16, stride16);
        udl_reg_write_3(sc, UDL_REG_ADDR_START8, start8);
        udl_reg_write_3(sc, UDL_REG_ADDR_STRIDE8, stride8);
        udl_reg_write_1(sc, UDL_REG_SYNC, 0xff);
}

static void
udl_blank(struct udl_softc *sc, int blank)
{

        if (blank != 0)
                udl_reg_write_1(sc, UDL_REG_BLANK, UDL_REG_BLANK_ON);
        else
                udl_reg_write_1(sc, UDL_REG_BLANK, UDL_REG_BLANK_OFF);
        udl_reg_write_1(sc, UDL_REG_SYNC, 0xff);
}

static uint16_t
udl_lfsr(uint16_t count)
{
        uint16_t val = 0xffff;

        while (count > 0) {
                val = (uint16_t)(val << 1) | ((uint16_t)(
                    (uint16_t)(val << 0) ^
                    (uint16_t)(val << 11) ^
                    (uint16_t)(val << 13) ^
                    (uint16_t)(val << 14)
                    ) >> 15);
                count--;
        }

        return val;
}

static int
udl_set_resolution(struct udl_softc *sc, const struct videomode *vmp)
{
        uint16_t val;
        int start16, stride16, start8, stride8;

        /* set video memory offsets */
        start16 = 0;
        stride16 = sc->sc_width * 2;
        start8 = stride16 * sc->sc_height;
        stride8 = sc->sc_width;
        udl_set_address(sc, start16, stride16, start8, stride8);

        /* write resolution values */
        udl_reg_write_1(sc, UDL_REG_SYNC, 0x00);
        udl_reg_write_1(sc, UDL_REG_COLORDEPTH, UDL_REG_COLORDEPTH_16);
        val = vmp->htotal - vmp->hsync_start;
        udl_reg_write_2(sc, UDL_REG_XDISPLAYSTART, udl_lfsr(val));
        val += vmp->hdisplay;
        udl_reg_write_2(sc, UDL_REG_XDISPLAYEND, udl_lfsr(val));
        val = vmp->vtotal - vmp->vsync_start;
        udl_reg_write_2(sc, UDL_REG_YDISPLAYSTART, udl_lfsr(val));
        val += vmp->vdisplay;
        udl_reg_write_2(sc, UDL_REG_YDISPLAYEND, udl_lfsr(val));
        val = vmp->htotal - 1;
        udl_reg_write_2(sc, UDL_REG_XENDCOUNT, udl_lfsr(val));
        val = vmp->hsync_end - vmp->hsync_start + 1;
        if (vmp->flags & VID_PHSYNC) {
                udl_reg_write_2(sc, UDL_REG_HSYNCSTART, udl_lfsr(1));
                udl_reg_write_2(sc, UDL_REG_HSYNCEND, udl_lfsr(val));
        } else {
                udl_reg_write_2(sc, UDL_REG_HSYNCSTART, udl_lfsr(val));
                udl_reg_write_2(sc, UDL_REG_HSYNCEND, udl_lfsr(1));
        }
        val = vmp->hdisplay;
        udl_reg_write_2(sc, UDL_REG_HPIXELS, val);
        val = vmp->vtotal;
        udl_reg_write_2(sc, UDL_REG_YENDCOUNT, udl_lfsr(val));
        val = vmp->vsync_end - vmp->vsync_start;
        if (vmp->flags & VID_PVSYNC) {
                udl_reg_write_2(sc, UDL_REG_VSYNCSTART, udl_lfsr(0));
                udl_reg_write_2(sc, UDL_REG_VSYNCEND, udl_lfsr(val));
        } else {
                udl_reg_write_2(sc, UDL_REG_VSYNCSTART, udl_lfsr(val));
                udl_reg_write_2(sc, UDL_REG_VSYNCEND, udl_lfsr(0));
        }
        val = vmp->vdisplay;
        udl_reg_write_2(sc, UDL_REG_VPIXELS, val);
        val = vmp->dot_clock / 5;
        udl_reg_write_2(sc, UDL_REG_PIXELCLOCK5KHZ, bswap16(val));
        udl_reg_write_1(sc, UDL_REG_SYNC, 0xff);

        if (udl_cmd_send(sc) != 0)
                return -1;

        /* clear screen */
        udl_fill_rect(sc, 0, 0, 0, sc->sc_width, sc->sc_height);

        if (udl_cmd_send(sc) != 0)
                return -1;

        /* show framebuffer content */
        udl_blank(sc, 0);

        if (udl_cmd_send(sc) != 0)
                return -1;

        sc->sc_blank = WSDISPLAYIO_VIDEO_ON;

        return 0;
}

static const struct videomode *
udl_videomode_lookup(const char *name)
{
        int i;

        for (i = 0; i < videomode_count; i++)
                if (strcmp(name, videomode_list[i].name) == 0)
                        return &videomode_list[i];

        return NULL;
}

static void
udl_update_thread(void *v)
{
        struct udl_softc *sc = v;
        uint16_t *fb, *fbcopy;
        int offs, stride, count = 0;

        mutex_enter(&sc->sc_thread_mtx);

        for (;;) {
                if (sc->sc_dying == true) {
                        mutex_exit(&sc->sc_thread_mtx);
                        kthread_exit(0);
                }

                if (sc->sc_thread_stop == true || sc->sc_fbmem == NULL ||
                    sc->sc_fbmem_prev == NULL || sc->sc_width <= 0)
                        goto thread_wait;

                if (sc->sc_clear == true)
                        count = 0;
                sc->sc_clear = false;

                stride = uimin(sc->sc_width, UDL_CMD_WIDTH_MAX - 8);
                stride /= 8;
                fb = (uint16_t *)sc->sc_fbmem;
                fbcopy = (uint16_t *)sc->sc_fbmem_prev;
                for (offs = 0; offs < (sc->sc_height * sc->sc_width) - stride;
                    offs += stride) {
                        if (count % (hz / 5) == 0 || memcmp(&fb[offs],
                            &fbcopy[offs], stride * sizeof(uint16_t)) != 0) {
                                udl_draw_line(sc, &fb[offs], offs, stride);
                                memcpy(&fbcopy[offs], &fb[offs], stride *
                                   sizeof(uint16_t));
                        }
                }
                count++;

                kpause("udlslp", false, 1, &sc->sc_thread_mtx);
                continue;

thread_wait:
                cv_wait(&sc->sc_thread_cv, &sc->sc_thread_mtx);
        }
}

static inline void
udl_startstop(struct udl_softc *sc, bool stop)
{
        mutex_enter(&sc->sc_thread_mtx);
        sc->sc_thread_stop = stop;
        if (!stop) {
                sc->sc_clear = true;
                cv_broadcast(&sc->sc_thread_cv);
        }
        mutex_exit(&sc->sc_thread_mtx);
}