// SPDX-License-Identifier: (GPL-2.0 OR BSD-3-Clause)
/*
 * sisusb - usb kernel driver for SiS315(E) based USB2VGA dongles
 *
 * VGA text mode console part
 *
 * Copyright (C) 2005 by Thomas Winischhofer, Vienna, Austria
 *
 * If distributed as part of the Linux kernel, this code is licensed under the
 * terms of the GPL v2.
 *
 * Otherwise, the following license terms apply:
 *
 * * 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.
 * * 3) The name of the author may not be used to endorse or promote products
 * *    derived from this software without specific psisusbr written permission.
 * *
 * * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESSED 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.
 *
 * Author: Thomas Winischhofer <thomas@winischhofer.net>
 *
 * Portions based on vgacon.c which are
 *      Created 28 Sep 1997 by Geert Uytterhoeven
 *      Rewritten by Martin Mares <mj@ucw.cz>, July 1998
 *      based on code Copyright (C) 1991, 1992  Linus Torvalds
 *                          1995  Jay Estabrook
 *
 * A note on using in_atomic() in here: We can't handle console
 * calls from non-schedulable context due to our USB-dependend
 * nature. For now, this driver just ignores any calls if it
 * detects this state.
 *
 */

#include <linux/mutex.h>
#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/signal.h>
#include <linux/fs.h>
#include <linux/usb.h>
#include <linux/tty.h>
#include <linux/console.h>
#include <linux/string.h>
#include <linux/kd.h>
#include <linux/init.h>
#include <linux/vt_kern.h>
#include <linux/selection.h>
#include <linux/spinlock.h>
#include <linux/kref.h>
#include <linux/ioport.h>
#include <linux/interrupt.h>
#include <linux/vmalloc.h>

#include "sisusb.h"
#include "sisusb_init.h"

/* vc_data -> sisusb conversion table */
static struct sisusb_usb_data *mysisusbs[MAX_NR_CONSOLES];

/* Forward declaration */
static const struct consw sisusb_con;

static inline void
sisusbcon_memsetw(u16 *s, u16 c, unsigned int count)
{
        memset16(s, c, count / 2);
}

static inline void
sisusb_initialize(struct sisusb_usb_data *sisusb)
{
        /* Reset cursor and start address */
        if (sisusb_setidxreg(sisusb, SISCR, 0x0c, 0x00))
                return;
        if (sisusb_setidxreg(sisusb, SISCR, 0x0d, 0x00))
                return;
        if (sisusb_setidxreg(sisusb, SISCR, 0x0e, 0x00))
                return;
        sisusb_setidxreg(sisusb, SISCR, 0x0f, 0x00);
}

static inline void
sisusbcon_set_start_address(struct sisusb_usb_data *sisusb, struct vc_data *c)
{
        sisusb->cur_start_addr = (c->vc_visible_origin - sisusb->scrbuf) / 2;

        sisusb_setidxreg(sisusb, SISCR, 0x0c, (sisusb->cur_start_addr >> 8));
        sisusb_setidxreg(sisusb, SISCR, 0x0d, (sisusb->cur_start_addr & 0xff));
}

void
sisusb_set_cursor(struct sisusb_usb_data *sisusb, unsigned int location)
{
        if (sisusb->sisusb_cursor_loc == location)
                return;

        sisusb->sisusb_cursor_loc = location;

        /* Hardware bug: Text cursor appears twice or not at all
         * at some positions. Work around it with the cursor skew
         * bits.
         */

        if ((location & 0x0007) == 0x0007) {
                sisusb->bad_cursor_pos = 1;
                location--;
                if (sisusb_setidxregandor(sisusb, SISCR, 0x0b, 0x1f, 0x20))
                        return;
        } else if (sisusb->bad_cursor_pos) {
                if (sisusb_setidxregand(sisusb, SISCR, 0x0b, 0x1f))
                        return;
                sisusb->bad_cursor_pos = 0;
        }

        if (sisusb_setidxreg(sisusb, SISCR, 0x0e, (location >> 8)))
                return;
        sisusb_setidxreg(sisusb, SISCR, 0x0f, (location & 0xff));
}

static inline struct sisusb_usb_data *
sisusb_get_sisusb(unsigned short console)
{
        return mysisusbs[console];
}

static inline int
sisusb_sisusb_valid(struct sisusb_usb_data *sisusb)
{
        if (!sisusb->present || !sisusb->ready || !sisusb->sisusb_dev)
                return 0;

        return 1;
}

static struct sisusb_usb_data *
sisusb_get_sisusb_lock_and_check(unsigned short console)
{
        struct sisusb_usb_data *sisusb;

        /* We can't handle console calls in non-schedulable
         * context due to our locks and the USB transport.
         * So we simply ignore them. This should only affect
         * some calls to printk.
         */
        if (in_atomic())
                return NULL;

        sisusb = sisusb_get_sisusb(console);
        if (!sisusb)
                return NULL;

        mutex_lock(&sisusb->lock);

        if (!sisusb_sisusb_valid(sisusb) ||
            !sisusb->havethisconsole[console]) {
                mutex_unlock(&sisusb->lock);
                return NULL;
        }

        return sisusb;
}

static int
sisusb_is_inactive(struct vc_data *c, struct sisusb_usb_data *sisusb)
{
        if (sisusb->is_gfx ||
            sisusb->textmodedestroyed ||
            c->vc_mode != KD_TEXT)
                return 1;

        return 0;
}

/* con_startup console interface routine */
static const char *
sisusbcon_startup(void)
{
        return "SISUSBCON";
}

/* con_init console interface routine */
static void
sisusbcon_init(struct vc_data *c, int init)
{
        struct sisusb_usb_data *sisusb;
        int cols, rows;

        /* This is called by do_take_over_console(),
         * ie by us/under our control. It is
         * only called after text mode and fonts
         * are set up/restored.
         */

        sisusb = sisusb_get_sisusb(c->vc_num);
        if (!sisusb)
                return;

        mutex_lock(&sisusb->lock);

        if (!sisusb_sisusb_valid(sisusb)) {
                mutex_unlock(&sisusb->lock);
                return;
        }

        c->vc_can_do_color = 1;

        c->vc_complement_mask = 0x7700;

        c->vc_hi_font_mask = sisusb->current_font_512 ? 0x0800 : 0;

        sisusb->haveconsole = 1;

        sisusb->havethisconsole[c->vc_num] = 1;

        /* We only support 640x400 */
        c->vc_scan_lines = 400;

        c->vc_font.height = sisusb->current_font_height;

        /* We only support width = 8 */
        cols = 80;
        rows = c->vc_scan_lines / c->vc_font.height;

        /* Increment usage count for our sisusb.
         * Doing so saves us from upping/downing
         * the disconnect semaphore; we can't
         * lose our sisusb until this is undone
         * in con_deinit. For all other console
         * interface functions, it suffices to
         * use sisusb->lock and do a quick check
         * of sisusb for device disconnection.
         */
        kref_get(&sisusb->kref);

        if (!*c->vc_uni_pagedir_loc)
                con_set_default_unimap(c);

        mutex_unlock(&sisusb->lock);

        if (init) {
                c->vc_cols = cols;
                c->vc_rows = rows;
        } else
                vc_resize(c, cols, rows);
}

/* con_deinit console interface routine */
static void
sisusbcon_deinit(struct vc_data *c)
{
        struct sisusb_usb_data *sisusb;
        int i;

        /* This is called by do_take_over_console()
         * and others, ie not under our control.
         */

        sisusb = sisusb_get_sisusb(c->vc_num);
        if (!sisusb)
                return;

        mutex_lock(&sisusb->lock);

        /* Clear ourselves in mysisusbs */
        mysisusbs[c->vc_num] = NULL;

        sisusb->havethisconsole[c->vc_num] = 0;

        /* Free our font buffer if all consoles are gone */
        if (sisusb->font_backup) {
                for(i = 0; i < MAX_NR_CONSOLES; i++) {
                        if (sisusb->havethisconsole[c->vc_num])
                                break;
                }
                if (i == MAX_NR_CONSOLES) {
                        vfree(sisusb->font_backup);
                        sisusb->font_backup = NULL;
                }
        }

        mutex_unlock(&sisusb->lock);

        /* decrement the usage count on our sisusb */
        kref_put(&sisusb->kref, sisusb_delete);
}

/* interface routine */
static u8
sisusbcon_build_attr(struct vc_data *c, u8 color, u8 intensity,
                            u8 blink, u8 underline, u8 reverse, u8 unused)
{
        u8 attr = color;

        if (underline)
                attr = (attr & 0xf0) | c->vc_ulcolor;
        else if (intensity == 0)
                attr = (attr & 0xf0) | c->vc_halfcolor;

        if (reverse)
                attr = ((attr) & 0x88) |
                       ((((attr) >> 4) |
                       ((attr) << 4)) & 0x77);

        if (blink)
                attr ^= 0x80;

        if (intensity == 2)
                attr ^= 0x08;

        return attr;
}

/* Interface routine */
static void
sisusbcon_invert_region(struct vc_data *vc, u16 *p, int count)
{
        /* Invert a region. This is called with a pointer
         * to the console's internal screen buffer. So we
         * simply do the inversion there and rely on
         * a call to putc(s) to update the real screen.
         */

        while (count--) {
                u16 a = *p;

                *p++ = ((a) & 0x88ff)        |
                       (((a) & 0x7000) >> 4) |
                       (((a) & 0x0700) << 4);
        }
}

static inline void *sisusb_vaddr(const struct sisusb_usb_data *sisusb,
                const struct vc_data *c, unsigned int x, unsigned int y)
{
        return (u16 *)c->vc_origin + y * sisusb->sisusb_num_columns + x;
}

static inline unsigned long sisusb_haddr(const struct sisusb_usb_data *sisusb,
              const struct vc_data *c, unsigned int x, unsigned int y)
{
        unsigned long offset = c->vc_origin - sisusb->scrbuf;

        /* 2 bytes per each character */
        offset += 2 * (y * sisusb->sisusb_num_columns + x);

        return sisusb->vrambase + offset;
}

/* Interface routine */
static void
sisusbcon_putc(struct vc_data *c, int ch, int y, int x)
{
        struct sisusb_usb_data *sisusb;

        sisusb = sisusb_get_sisusb_lock_and_check(c->vc_num);
        if (!sisusb)
                return;

        /* sisusb->lock is down */
        if (sisusb_is_inactive(c, sisusb)) {
                mutex_unlock(&sisusb->lock);
                return;
        }

        sisusb_copy_memory(sisusb, sisusb_vaddr(sisusb, c, x, y),
                                sisusb_haddr(sisusb, c, x, y), 2);

        mutex_unlock(&sisusb->lock);
}

/* Interface routine */
static void
sisusbcon_putcs(struct vc_data *c, const unsigned short *s,
                         int count, int y, int x)
{
        struct sisusb_usb_data *sisusb;

        sisusb = sisusb_get_sisusb_lock_and_check(c->vc_num);
        if (!sisusb)
                return;

        /* sisusb->lock is down */

        /* Need to put the characters into the buffer ourselves,
         * because the vt does this AFTER calling us.
         */

        memcpy(sisusb_vaddr(sisusb, c, x, y), s, count * 2);

        if (sisusb_is_inactive(c, sisusb)) {
                mutex_unlock(&sisusb->lock);
                return;
        }

        sisusb_copy_memory(sisusb, sisusb_vaddr(sisusb, c, x, y),
                        sisusb_haddr(sisusb, c, x, y), count * 2);

        mutex_unlock(&sisusb->lock);
}

/* Interface routine */
static void
sisusbcon_clear(struct vc_data *c, int y, int x, int height, int width)
{
        struct sisusb_usb_data *sisusb;
        u16 eattr = c->vc_video_erase_char;
        int i, length, cols;
        u16 *dest;

        if (width <= 0 || height <= 0)
                return;

        sisusb = sisusb_get_sisusb_lock_and_check(c->vc_num);
        if (!sisusb)
                return;

        /* sisusb->lock is down */

        /* Need to clear buffer ourselves, because the vt does
         * this AFTER calling us.
         */

        dest = sisusb_vaddr(sisusb, c, x, y);

        cols = sisusb->sisusb_num_columns;

        if (width > cols)
                width = cols;

        if (x == 0 && width >= c->vc_cols) {

                sisusbcon_memsetw(dest, eattr, height * cols * 2);

        } else {

                for (i = height; i > 0; i--, dest += cols)
                        sisusbcon_memsetw(dest, eattr, width * 2);

        }

        if (sisusb_is_inactive(c, sisusb)) {
                mutex_unlock(&sisusb->lock);
                return;
        }

        length = ((height * cols) - x - (cols - width - x)) * 2;


        sisusb_copy_memory(sisusb, sisusb_vaddr(sisusb, c, x, y),
                        sisusb_haddr(sisusb, c, x, y), length);

        mutex_unlock(&sisusb->lock);
}

/* interface routine */
static int
sisusbcon_switch(struct vc_data *c)
{
        struct sisusb_usb_data *sisusb;
        int length;

        /* Returnvalue 0 means we have fully restored screen,
         *      and vt doesn't need to call do_update_region().
         * Returnvalue != 0 naturally means the opposite.
         */

        sisusb = sisusb_get_sisusb_lock_and_check(c->vc_num);
        if (!sisusb)
                return 0;

        /* sisusb->lock is down */

        /* Don't write to screen if in gfx mode */
        if (sisusb_is_inactive(c, sisusb)) {
                mutex_unlock(&sisusb->lock);
                return 0;
        }

        /* That really should not happen. It would mean we are
         * being called while the vc is using its private buffer
         * as origin.
         */
        if (c->vc_origin == (unsigned long)c->vc_screenbuf) {
                mutex_unlock(&sisusb->lock);
                dev_dbg(&sisusb->sisusb_dev->dev, "ASSERT ORIGIN != SCREENBUF!\n");
                return 0;
        }

        /* Check that we don't copy too much */
        length = min((int)c->vc_screenbuf_size,
                        (int)(sisusb->scrbuf + sisusb->scrbuf_size - c->vc_origin));

        /* Restore the screen contents */
        memcpy((u16 *)c->vc_origin, (u16 *)c->vc_screenbuf, length);

        sisusb_copy_memory(sisusb, (char *)c->vc_origin,
                        sisusb_haddr(sisusb, c, 0, 0), length);

        mutex_unlock(&sisusb->lock);

        return 0;
}

/* interface routine */
static void
sisusbcon_save_screen(struct vc_data *c)
{
        struct sisusb_usb_data *sisusb;
        int length;

        /* Save the current screen contents to vc's private
         * buffer.
         */

        sisusb = sisusb_get_sisusb_lock_and_check(c->vc_num);
        if (!sisusb)
                return;

        /* sisusb->lock is down */

        if (sisusb_is_inactive(c, sisusb)) {
                mutex_unlock(&sisusb->lock);
                return;
        }

        /* Check that we don't copy too much */
        length = min((int)c->vc_screenbuf_size,
                        (int)(sisusb->scrbuf + sisusb->scrbuf_size - c->vc_origin));

        /* Save the screen contents to vc's private buffer */
        memcpy((u16 *)c->vc_screenbuf, (u16 *)c->vc_origin, length);

        mutex_unlock(&sisusb->lock);
}

/* interface routine */
static void
sisusbcon_set_palette(struct vc_data *c, const unsigned char *table)
{
        struct sisusb_usb_data *sisusb;
        int i, j;

        /* Return value not used by vt */

        if (!con_is_visible(c))
                return;

        sisusb = sisusb_get_sisusb_lock_and_check(c->vc_num);
        if (!sisusb)
                return;

        /* sisusb->lock is down */

        if (sisusb_is_inactive(c, sisusb)) {
                mutex_unlock(&sisusb->lock);
                return;
        }

        for (i = j = 0; i < 16; i++) {
                if (sisusb_setreg(sisusb, SISCOLIDX, table[i]))
                        break;
                if (sisusb_setreg(sisusb, SISCOLDATA, c->vc_palette[j++] >> 2))
                        break;
                if (sisusb_setreg(sisusb, SISCOLDATA, c->vc_palette[j++] >> 2))
                        break;
                if (sisusb_setreg(sisusb, SISCOLDATA, c->vc_palette[j++] >> 2))
                        break;
        }

        mutex_unlock(&sisusb->lock);
}

/* interface routine */
static int
sisusbcon_blank(struct vc_data *c, int blank, int mode_switch)
{
        struct sisusb_usb_data *sisusb;
        u8 sr1, cr17, pmreg, cr63;
        int ret = 0;

        sisusb = sisusb_get_sisusb_lock_and_check(c->vc_num);
        if (!sisusb)
                return 0;

        /* sisusb->lock is down */

        if (mode_switch)
                sisusb->is_gfx = blank ? 1 : 0;

        if (sisusb_is_inactive(c, sisusb)) {
                mutex_unlock(&sisusb->lock);
                return 0;
        }

        switch (blank) {

        case 1:         /* Normal blanking: Clear screen */
        case -1:
                sisusbcon_memsetw((u16 *)c->vc_origin,
                                c->vc_video_erase_char,
                                c->vc_screenbuf_size);
                sisusb_copy_memory(sisusb, (char *)c->vc_origin,
                                sisusb_haddr(sisusb, c, 0, 0),
                                c->vc_screenbuf_size);
                sisusb->con_blanked = 1;
                ret = 1;
                break;

        default:        /* VESA blanking */
                switch (blank) {
                case 0: /* Unblank */
                        sr1   = 0x00;
                        cr17  = 0x80;
                        pmreg = 0x00;
                        cr63  = 0x00;
                        ret = 1;
                        sisusb->con_blanked = 0;
                        break;
                case VESA_VSYNC_SUSPEND + 1:
                        sr1   = 0x20;
                        cr17  = 0x80;
                        pmreg = 0x80;
                        cr63  = 0x40;
                        break;
                case VESA_HSYNC_SUSPEND + 1:
                        sr1   = 0x20;
                        cr17  = 0x80;
                        pmreg = 0x40;
                        cr63  = 0x40;
                        break;
                case VESA_POWERDOWN + 1:
                        sr1   = 0x20;
                        cr17  = 0x00;
                        pmreg = 0xc0;
                        cr63  = 0x40;
                        break;
                default:
                        mutex_unlock(&sisusb->lock);
                        return -EINVAL;
                }

                sisusb_setidxregandor(sisusb, SISSR, 0x01, ~0x20, sr1);
                sisusb_setidxregandor(sisusb, SISCR, 0x17, 0x7f, cr17);
                sisusb_setidxregandor(sisusb, SISSR, 0x1f, 0x3f, pmreg);
                sisusb_setidxregandor(sisusb, SISCR, 0x63, 0xbf, cr63);

        }

        mutex_unlock(&sisusb->lock);

        return ret;
}

/* interface routine */
static void
sisusbcon_scrolldelta(struct vc_data *c, int lines)
{
        struct sisusb_usb_data *sisusb;

        sisusb = sisusb_get_sisusb_lock_and_check(c->vc_num);
        if (!sisusb)
                return;

        /* sisusb->lock is down */

        if (sisusb_is_inactive(c, sisusb)) {
                mutex_unlock(&sisusb->lock);
                return;
        }

        vc_scrolldelta_helper(c, lines, sisusb->con_rolled_over,
                        (void *)sisusb->scrbuf, sisusb->scrbuf_size);

        sisusbcon_set_start_address(sisusb, c);

        mutex_unlock(&sisusb->lock);
}

/* Interface routine */
static void
sisusbcon_cursor(struct vc_data *c, int mode)
{
        struct sisusb_usb_data *sisusb;
        int from, to, baseline;

        sisusb = sisusb_get_sisusb_lock_and_check(c->vc_num);
        if (!sisusb)
                return;

        /* sisusb->lock is down */

        if (sisusb_is_inactive(c, sisusb)) {
                mutex_unlock(&sisusb->lock);
                return;
        }

        if (c->vc_origin != c->vc_visible_origin) {
                c->vc_visible_origin = c->vc_origin;
                sisusbcon_set_start_address(sisusb, c);
        }

        if (mode == CM_ERASE) {
                sisusb_setidxregor(sisusb, SISCR, 0x0a, 0x20);
                sisusb->sisusb_cursor_size_to = -1;
                mutex_unlock(&sisusb->lock);
                return;
        }

        sisusb_set_cursor(sisusb, (c->vc_pos - sisusb->scrbuf) / 2);

        baseline = c->vc_font.height - (c->vc_font.height < 10 ? 1 : 2);

        switch (c->vc_cursor_type & 0x0f) {
                case CUR_BLOCK:         from = 1;
                                        to   = c->vc_font.height;
                                        break;
                case CUR_TWO_THIRDS:    from = c->vc_font.height / 3;
                                        to   = baseline;
                                        break;
                case CUR_LOWER_HALF:    from = c->vc_font.height / 2;
                                        to   = baseline;
                                        break;
                case CUR_LOWER_THIRD:   from = (c->vc_font.height * 2) / 3;
                                        to   = baseline;
                                        break;
                case CUR_NONE:          from = 31;
                                        to = 30;
                                        break;
                default:
                case CUR_UNDERLINE:     from = baseline - 1;
                                        to   = baseline;
                                        break;
        }

        if (sisusb->sisusb_cursor_size_from != from ||
            sisusb->sisusb_cursor_size_to != to) {

                sisusb_setidxreg(sisusb, SISCR, 0x0a, from);
                sisusb_setidxregandor(sisusb, SISCR, 0x0b, 0xe0, to);

                sisusb->sisusb_cursor_size_from = from;
                sisusb->sisusb_cursor_size_to   = to;
        }

        mutex_unlock(&sisusb->lock);
}

static bool
sisusbcon_scroll_area(struct vc_data *c, struct sisusb_usb_data *sisusb,
                unsigned int t, unsigned int b, enum con_scroll dir,
                unsigned int lines)
{
        int cols = sisusb->sisusb_num_columns;
        int length = ((b - t) * cols) * 2;
        u16 eattr = c->vc_video_erase_char;

        /* sisusb->lock is down */

        /* Scroll an area which does not match the
         * visible screen's dimensions. This needs
         * to be done separately, as it does not
         * use hardware panning.
         */

        switch (dir) {

                case SM_UP:
                        memmove(sisusb_vaddr(sisusb, c, 0, t),
                                           sisusb_vaddr(sisusb, c, 0, t + lines),
                                           (b - t - lines) * cols * 2);
                        sisusbcon_memsetw(sisusb_vaddr(sisusb, c, 0, b - lines),
                                        eattr, lines * cols * 2);
                        break;

                case SM_DOWN:
                        memmove(sisusb_vaddr(sisusb, c, 0, t + lines),
                                           sisusb_vaddr(sisusb, c, 0, t),
                                           (b - t - lines) * cols * 2);
                        sisusbcon_memsetw(sisusb_vaddr(sisusb, c, 0, t), eattr,
                                          lines * cols * 2);
                        break;
        }

        sisusb_copy_memory(sisusb, sisusb_vaddr(sisusb, c, 0, t),
                        sisusb_haddr(sisusb, c, 0, t), length);

        mutex_unlock(&sisusb->lock);

        return true;
}

/* Interface routine */
static bool
sisusbcon_scroll(struct vc_data *c, unsigned int t, unsigned int b,
                enum con_scroll dir, unsigned int lines)
{
        struct sisusb_usb_data *sisusb;
        u16 eattr = c->vc_video_erase_char;
        int copyall = 0;
        unsigned long oldorigin;
        unsigned int delta = lines * c->vc_size_row;

        /* Returning != 0 means we have done the scrolling successfully.
         * Returning 0 makes vt do the scrolling on its own.
         * Note that con_scroll is only called if the console is
         * visible. In that case, the origin should be our buffer,
         * not the vt's private one.
         */

        if (!lines)
                return true;

        sisusb = sisusb_get_sisusb_lock_and_check(c->vc_num);
        if (!sisusb)
                return false;

        /* sisusb->lock is down */

        if (sisusb_is_inactive(c, sisusb)) {
                mutex_unlock(&sisusb->lock);
                return false;
        }

        /* Special case */
        if (t || b != c->vc_rows)
                return sisusbcon_scroll_area(c, sisusb, t, b, dir, lines);

        if (c->vc_origin != c->vc_visible_origin) {
                c->vc_visible_origin = c->vc_origin;
                sisusbcon_set_start_address(sisusb, c);
        }

        /* limit amount to maximum realistic size */
        if (lines > c->vc_rows)
                lines = c->vc_rows;

        oldorigin = c->vc_origin;

        switch (dir) {

        case SM_UP:

                if (c->vc_scr_end + delta >=
                                sisusb->scrbuf + sisusb->scrbuf_size) {
                        memcpy((u16 *)sisusb->scrbuf,
                                          (u16 *)(oldorigin + delta),
                                          c->vc_screenbuf_size - delta);
                        c->vc_origin = sisusb->scrbuf;
                        sisusb->con_rolled_over = oldorigin - sisusb->scrbuf;
                        copyall = 1;
                } else
                        c->vc_origin += delta;

                sisusbcon_memsetw(
                        (u16 *)(c->vc_origin + c->vc_screenbuf_size - delta),
                                        eattr, delta);

                break;

        case SM_DOWN:

                if (oldorigin - delta < sisusb->scrbuf) {
                        memmove((void *)sisusb->scrbuf + sisusb->scrbuf_size -
                                        c->vc_screenbuf_size + delta,
                                        (u16 *)oldorigin,
                                        c->vc_screenbuf_size - delta);
                        c->vc_origin = sisusb->scrbuf +
                                        sisusb->scrbuf_size -
                                        c->vc_screenbuf_size;
                        sisusb->con_rolled_over = 0;
                        copyall = 1;
                } else
                        c->vc_origin -= delta;

                c->vc_scr_end = c->vc_origin + c->vc_screenbuf_size;

                scr_memsetw((u16 *)(c->vc_origin), eattr, delta);

                break;
        }

        if (copyall)
                sisusb_copy_memory(sisusb,
                        (char *)c->vc_origin,
                        sisusb_haddr(sisusb, c, 0, 0),
                        c->vc_screenbuf_size);
        else if (dir == SM_UP)
                sisusb_copy_memory(sisusb,
                        (char *)c->vc_origin + c->vc_screenbuf_size - delta,
                        sisusb_haddr(sisusb, c, 0, 0) +
                                        c->vc_screenbuf_size - delta,
                        delta);
        else
                sisusb_copy_memory(sisusb,
                        (char *)c->vc_origin,
                        sisusb_haddr(sisusb, c, 0, 0),
                        delta);

        c->vc_scr_end = c->vc_origin + c->vc_screenbuf_size;
        c->vc_visible_origin = c->vc_origin;

        sisusbcon_set_start_address(sisusb, c);

        c->vc_pos = c->vc_pos - oldorigin + c->vc_origin;

        mutex_unlock(&sisusb->lock);

        return true;
}

/* Interface routine */
static int
sisusbcon_set_origin(struct vc_data *c)
{
        struct sisusb_usb_data *sisusb;

        /* Returning != 0 means we were successful.
         * Returning 0 will vt make to use its own
         *      screenbuffer as the origin.
         */

        sisusb = sisusb_get_sisusb_lock_and_check(c->vc_num);
        if (!sisusb)
                return 0;

        /* sisusb->lock is down */

        if (sisusb_is_inactive(c, sisusb) || sisusb->con_blanked) {
                mutex_unlock(&sisusb->lock);
                return 0;
        }

        c->vc_origin = c->vc_visible_origin = sisusb->scrbuf;

        sisusbcon_set_start_address(sisusb, c);

        sisusb->con_rolled_over = 0;

        mutex_unlock(&sisusb->lock);

        return true;
}

/* Interface routine */
static int
sisusbcon_resize(struct vc_data *c, unsigned int newcols, unsigned int newrows,
                 unsigned int user)
{
        struct sisusb_usb_data *sisusb;
        int fh;

        sisusb = sisusb_get_sisusb_lock_and_check(c->vc_num);
        if (!sisusb)
                return -ENODEV;

        fh = sisusb->current_font_height;

        mutex_unlock(&sisusb->lock);

        /* We are quite unflexible as regards resizing. The vt code
         * handles sizes where the line length isn't equal the pitch
         * quite badly. As regards the rows, our panning tricks only
         * work well if the number of rows equals the visible number
         * of rows.
         */

        if (newcols != 80 || c->vc_scan_lines / fh != newrows)
                return -EINVAL;

        return 0;
}

int
sisusbcon_do_font_op(struct sisusb_usb_data *sisusb, int set, int slot,
                        u8 *arg, int cmapsz, int ch512, int dorecalc,
                        struct vc_data *c, int fh, int uplock)
{
        int font_select = 0x00, i, err = 0;
        u32 offset = 0;
        u8 dummy;

        /* sisusb->lock is down */

        /*

         * The default font is kept in slot 0.
         * A user font is loaded in slot 2 (256 ch)
         * or 2+3 (512 ch).
         */

        if ((slot != 0 && slot != 2) || !fh) {
                if (uplock)
                        mutex_unlock(&sisusb->lock);
                return -EINVAL;
        }

        if (set)
                sisusb->font_slot = slot;

        /* Default font is always 256 */
        if (slot == 0)
                ch512 = 0;
        else
                offset = 4 * cmapsz;

        font_select = (slot == 0) ? 0x00 : (ch512 ? 0x0e : 0x0a);

        err |= sisusb_setidxreg(sisusb, SISSR, 0x00, 0x01); /* Reset */
        err |= sisusb_setidxreg(sisusb, SISSR, 0x02, 0x04); /* Write to plane 2 */
        err |= sisusb_setidxreg(sisusb, SISSR, 0x04, 0x07); /* Memory mode a0-bf */
        err |= sisusb_setidxreg(sisusb, SISSR, 0x00, 0x03); /* Reset */

        if (err)
                goto font_op_error;

        err |= sisusb_setidxreg(sisusb, SISGR, 0x04, 0x03); /* Select plane read 2 */
        err |= sisusb_setidxreg(sisusb, SISGR, 0x05, 0x00); /* Disable odd/even */
        err |= sisusb_setidxreg(sisusb, SISGR, 0x06, 0x00); /* Address range a0-bf */

        if (err)
                goto font_op_error;

        if (arg) {
                if (set)
                        for (i = 0; i < cmapsz; i++) {
                                err |= sisusb_writeb(sisusb,
                                        sisusb->vrambase + offset + i,
                                        arg[i]);
                                if (err)
                                        break;
                        }
                else
                        for (i = 0; i < cmapsz; i++) {
                                err |= sisusb_readb(sisusb,
                                        sisusb->vrambase + offset + i,
                                        &arg[i]);
                                if (err)
                                        break;
                        }

                /*
                 * In 512-character mode, the character map is not contiguous if
                 * we want to remain EGA compatible -- which we do
                 */

                if (ch512) {
                        if (set)
                                for (i = 0; i < cmapsz; i++) {
                                        err |= sisusb_writeb(sisusb,
                                                sisusb->vrambase + offset +
                                                        (2 * cmapsz) + i,
                                                arg[cmapsz + i]);
                                        if (err)
                                                break;
                                }
                        else
                                for (i = 0; i < cmapsz; i++) {
                                        err |= sisusb_readb(sisusb,
                                                sisusb->vrambase + offset +
                                                        (2 * cmapsz) + i,
                                                &arg[cmapsz + i]);
                                        if (err)
                                                break;
                                }
                }
        }

        if (err)
                goto font_op_error;

        err |= sisusb_setidxreg(sisusb, SISSR, 0x00, 0x01); /* Reset */
        err |= sisusb_setidxreg(sisusb, SISSR, 0x02, 0x03); /* Write to planes 0+1 */
        err |= sisusb_setidxreg(sisusb, SISSR, 0x04, 0x03); /* Memory mode a0-bf */
        if (set)
                sisusb_setidxreg(sisusb, SISSR, 0x03, font_select);
        err |= sisusb_setidxreg(sisusb, SISSR, 0x00, 0x03); /* Reset end */

        if (err)
                goto font_op_error;

        err |= sisusb_setidxreg(sisusb, SISGR, 0x04, 0x00); /* Select plane read 0 */
        err |= sisusb_setidxreg(sisusb, SISGR, 0x05, 0x10); /* Enable odd/even */
        err |= sisusb_setidxreg(sisusb, SISGR, 0x06, 0x06); /* Address range b8-bf */

        if (err)
                goto font_op_error;

        if ((set) && (ch512 != sisusb->current_font_512)) {

                /* Font is shared among all our consoles.
                 * And so is the hi_font_mask.
                 */
                for (i = 0; i < MAX_NR_CONSOLES; i++) {
                        struct vc_data *d = vc_cons[i].d;
                        if (d && d->vc_sw == &sisusb_con)
                                d->vc_hi_font_mask = ch512 ? 0x0800 : 0;
                }

                sisusb->current_font_512 = ch512;

                /* color plane enable register:
                        256-char: enable intensity bit
                        512-char: disable intensity bit */
                sisusb_getreg(sisusb, SISINPSTAT, &dummy);
                sisusb_setreg(sisusb, SISAR, 0x12);
                sisusb_setreg(sisusb, SISAR, ch512 ? 0x07 : 0x0f);

                sisusb_getreg(sisusb, SISINPSTAT, &dummy);
                sisusb_setreg(sisusb, SISAR, 0x20);
                sisusb_getreg(sisusb, SISINPSTAT, &dummy);
        }

        if (dorecalc) {

                /*
                 * Adjust the screen to fit a font of a certain height
                 */

                unsigned char ovr, vde, fsr;
                int rows = 0, maxscan = 0;

                if (c) {

                        /* Number of video rows */
                        rows = c->vc_scan_lines / fh;
                        /* Scan lines to actually display-1 */
                        maxscan = rows * fh - 1;

                        /*printk(KERN_DEBUG "sisusb recalc rows %d maxscan %d fh %d sl %d\n",
                                rows, maxscan, fh, c->vc_scan_lines);*/

                        sisusb_getidxreg(sisusb, SISCR, 0x07, &ovr);
                        vde = maxscan & 0xff;
                        ovr = (ovr & 0xbd) |
                              ((maxscan & 0x100) >> 7) |
                              ((maxscan & 0x200) >> 3);
                        sisusb_setidxreg(sisusb, SISCR, 0x07, ovr);
                        sisusb_setidxreg(sisusb, SISCR, 0x12, vde);

                }

                sisusb_getidxreg(sisusb, SISCR, 0x09, &fsr);
                fsr = (fsr & 0xe0) | (fh - 1);
                sisusb_setidxreg(sisusb, SISCR, 0x09, fsr);
                sisusb->current_font_height = fh;

                sisusb->sisusb_cursor_size_from = -1;
                sisusb->sisusb_cursor_size_to   = -1;

        }

        if (uplock)
                mutex_unlock(&sisusb->lock);

        if (dorecalc && c) {
                int rows = c->vc_scan_lines / fh;

                /* Now adjust our consoles' size */

                for (i = 0; i < MAX_NR_CONSOLES; i++) {
                        struct vc_data *vc = vc_cons[i].d;

                        if (vc && vc->vc_sw == &sisusb_con) {
                                if (con_is_visible(vc)) {
                                        vc->vc_sw->con_cursor(vc, CM_DRAW);
                                }
                                vc->vc_font.height = fh;
                                vc_resize(vc, 0, rows);
                        }
                }
        }

        return 0;

font_op_error:
        if (uplock)
                mutex_unlock(&sisusb->lock);

        return -EIO;
}

/* Interface routine */
static int
sisusbcon_font_set(struct vc_data *c, struct console_font *font,
                   unsigned int flags)
{
        struct sisusb_usb_data *sisusb;
        unsigned charcount = font->charcount;

        if (font->width != 8 || (charcount != 256 && charcount != 512))
                return -EINVAL;

        sisusb = sisusb_get_sisusb_lock_and_check(c->vc_num);
        if (!sisusb)
                return -ENODEV;

        /* sisusb->lock is down */

        /* Save the user-provided font into a buffer. This
         * is used for restoring text mode after quitting
         * from X and for the con_getfont routine.
         */
        if (sisusb->font_backup) {
                if (sisusb->font_backup_size < charcount) {
                        vfree(sisusb->font_backup);
                        sisusb->font_backup = NULL;
                }
        }

        if (!sisusb->font_backup)
                sisusb->font_backup = vmalloc(array_size(charcount, 32));

        if (sisusb->font_backup) {
                memcpy(sisusb->font_backup, font->data, charcount * 32);
                sisusb->font_backup_size = charcount;
                sisusb->font_backup_height = font->height;
                sisusb->font_backup_512 = (charcount == 512) ? 1 : 0;
        }

        /* do_font_op ups sisusb->lock */

        return sisusbcon_do_font_op(sisusb, 1, 2, font->data,
                        8192, (charcount == 512),
                        (!(flags & KD_FONT_FLAG_DONT_RECALC)) ? 1 : 0,
                        c, font->height, 1);
}

/* Interface routine */
static int
sisusbcon_font_get(struct vc_data *c, struct console_font *font)
{
        struct sisusb_usb_data *sisusb;

        sisusb = sisusb_get_sisusb_lock_and_check(c->vc_num);
        if (!sisusb)
                return -ENODEV;

        /* sisusb->lock is down */

        font->width = 8;
        font->height = c->vc_font.height;
        font->charcount = 256;

        if (!font->data) {
                mutex_unlock(&sisusb->lock);
                return 0;
        }

        if (!sisusb->font_backup) {
                mutex_unlock(&sisusb->lock);
                return -ENODEV;
        }

        /* Copy 256 chars only, like vgacon */
        memcpy(font->data, sisusb->font_backup, 256 * 32);

        mutex_unlock(&sisusb->lock);

        return 0;
}

/*
 *  The console `switch' structure for the sisusb console
 */

static const struct consw sisusb_con = {
        .owner =                THIS_MODULE,
        .con_startup =          sisusbcon_startup,
        .con_init =             sisusbcon_init,
        .con_deinit =           sisusbcon_deinit,
        .con_clear =            sisusbcon_clear,
        .con_putc =             sisusbcon_putc,
        .con_putcs =            sisusbcon_putcs,
        .con_cursor =           sisusbcon_cursor,
        .con_scroll =           sisusbcon_scroll,
        .con_switch =           sisusbcon_switch,
        .con_blank =            sisusbcon_blank,
        .con_font_set =         sisusbcon_font_set,
        .con_font_get =         sisusbcon_font_get,
        .con_set_palette =      sisusbcon_set_palette,
        .con_scrolldelta =      sisusbcon_scrolldelta,
        .con_build_attr =       sisusbcon_build_attr,
        .con_invert_region =    sisusbcon_invert_region,
        .con_set_origin =       sisusbcon_set_origin,
        .con_save_screen =      sisusbcon_save_screen,
        .con_resize =           sisusbcon_resize,
};

/* Our very own dummy console driver */

static const char *sisusbdummycon_startup(void)
{
    return "SISUSBVGADUMMY";
}

static void sisusbdummycon_init(struct vc_data *vc, int init)
{
    vc->vc_can_do_color = 1;
    if (init) {
        vc->vc_cols = 80;
        vc->vc_rows = 25;
    } else
        vc_resize(vc, 80, 25);
}

static void sisusbdummycon_deinit(struct vc_data *vc) { }
static void sisusbdummycon_clear(struct vc_data *vc, int sy, int sx,
                                 int height, int width) { }
static void sisusbdummycon_putc(struct vc_data *vc, int c, int ypos,
                                int xpos) { }
static void sisusbdummycon_putcs(struct vc_data *vc, const unsigned short *s,
                                 int count, int ypos, int xpos) { }
static void sisusbdummycon_cursor(struct vc_data *vc, int mode) { }

static bool sisusbdummycon_scroll(struct vc_data *vc, unsigned int top,
                                  unsigned int bottom, enum con_scroll dir,
                                  unsigned int lines)
{
        return false;
}

static int sisusbdummycon_switch(struct vc_data *vc)
{
        return 0;
}

static int sisusbdummycon_blank(struct vc_data *vc, int blank, int mode_switch)
{
        return 0;
}

static int sisusbdummycon_font_set(struct vc_data *vc,
                                   struct console_font *font,
                                   unsigned int flags)
{
        return 0;
}

static int sisusbdummycon_font_default(struct vc_data *vc,
                                       struct console_font *font, char *name)
{
        return 0;
}

static int sisusbdummycon_font_copy(struct vc_data *vc, int con)
{
        return 0;
}

static const struct consw sisusb_dummy_con = {
        .owner =                THIS_MODULE,
        .con_startup =          sisusbdummycon_startup,
        .con_init =             sisusbdummycon_init,
        .con_deinit =           sisusbdummycon_deinit,
        .con_clear =            sisusbdummycon_clear,
        .con_putc =             sisusbdummycon_putc,
        .con_putcs =            sisusbdummycon_putcs,
        .con_cursor =           sisusbdummycon_cursor,
        .con_scroll =           sisusbdummycon_scroll,
        .con_switch =           sisusbdummycon_switch,
        .con_blank =            sisusbdummycon_blank,
        .con_font_set =         sisusbdummycon_font_set,
        .con_font_default =     sisusbdummycon_font_default,
        .con_font_copy =        sisusbdummycon_font_copy,
};

int
sisusb_console_init(struct sisusb_usb_data *sisusb, int first, int last)
{
        int i, ret;

        mutex_lock(&sisusb->lock);

        /* Erm.. that should not happen */
        if (sisusb->haveconsole || !sisusb->SiS_Pr) {
                mutex_unlock(&sisusb->lock);
                return 1;
        }

        sisusb->con_first = first;
        sisusb->con_last  = last;

        if (first > last ||
            first > MAX_NR_CONSOLES ||
            last > MAX_NR_CONSOLES) {
                mutex_unlock(&sisusb->lock);
                return 1;
        }

        /* If gfxcore not initialized or no consoles given, quit graciously */
        if (!sisusb->gfxinit || first < 1 || last < 1) {
                mutex_unlock(&sisusb->lock);
                return 0;
        }

        sisusb->sisusb_cursor_loc       = -1;
        sisusb->sisusb_cursor_size_from = -1;
        sisusb->sisusb_cursor_size_to   = -1;

        /* Set up text mode (and upload  default font) */
        if (sisusb_reset_text_mode(sisusb, 1)) {
                mutex_unlock(&sisusb->lock);
                dev_err(&sisusb->sisusb_dev->dev, "Failed to set up text mode\n");
                return 1;
        }

        /* Initialize some gfx registers */
        sisusb_initialize(sisusb);

        for (i = first - 1; i <= last - 1; i++) {
                /* Save sisusb for our interface routines */
                mysisusbs[i] = sisusb;
        }

        /* Initial console setup */
        sisusb->sisusb_num_columns = 80;

        /* Use a 32K buffer (matches b8000-bffff area) */
        sisusb->scrbuf_size = 32 * 1024;

        /* Allocate screen buffer */
        if (!(sisusb->scrbuf = (unsigned long)vmalloc(sisusb->scrbuf_size))) {
                mutex_unlock(&sisusb->lock);
                dev_err(&sisusb->sisusb_dev->dev, "Failed to allocate screen buffer\n");
                return 1;
        }

        mutex_unlock(&sisusb->lock);

        /* Now grab the desired console(s) */
        console_lock();
        ret = do_take_over_console(&sisusb_con, first - 1, last - 1, 0);
        console_unlock();
        if (!ret)
                sisusb->haveconsole = 1;
        else {
                for (i = first - 1; i <= last - 1; i++)
                        mysisusbs[i] = NULL;
        }

        return ret;
}

void
sisusb_console_exit(struct sisusb_usb_data *sisusb)
{
        int i;

        /* This is called if the device is disconnected
         * and while disconnect and lock semaphores
         * are up. This should be save because we
         * can't lose our sisusb any other way but by
         * disconnection (and hence, the disconnect
         * sema is for protecting all other access
         * functions from disconnection, not the
         * other way round).
         */

        /* Now what do we do in case of disconnection:
         * One alternative would be to simply call
         * give_up_console(). Nah, not a good idea.
         * give_up_console() is obviously buggy as it
         * only discards the consw pointer from the
         * driver_map, but doesn't adapt vc->vc_sw
         * of the affected consoles. Hence, the next
         * call to any of the console functions will
         * eventually take a trip to oops county.
         * Also, give_up_console for some reason
         * doesn't decrement our module refcount.
         * Instead, we switch our consoles to a private
         * dummy console. This, of course, keeps our
         * refcount up as well, but it works perfectly.
         */

        if (sisusb->haveconsole) {
                for (i = 0; i < MAX_NR_CONSOLES; i++)
                        if (sisusb->havethisconsole[i]) {
                                console_lock();
                                do_take_over_console(&sisusb_dummy_con, i, i, 0);
                                console_unlock();
                                /* At this point, con_deinit for all our
                                 * consoles is executed by do_take_over_console().
                                 */
                        }
                sisusb->haveconsole = 0;
        }

        vfree((void *)sisusb->scrbuf);
        sisusb->scrbuf = 0;

        vfree(sisusb->font_backup);
        sisusb->font_backup = NULL;
}

void __init sisusb_init_concode(void)
{
        int i;

        for (i = 0; i < MAX_NR_CONSOLES; i++)
                mysisusbs[i] = NULL;
}