path: root/drivers/usb/misc/sisusbvga/sisusb_con.c

// 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 */