drivers/char/hvc_lguest.c

/* Simple console for lguest.
 *
 * Copyright (C) 2006 Rusty Russell, IBM Corporation
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 */
#include <linux/err.h>
#include <linux/init.h>
#include <linux/lguest_bus.h>
#include "hvc_console.h"

static char inbuf[256];
static struct lguest_dma cons_input = { .used_len = 0,
					.addr[0] = __pa(inbuf),
					.len[0] = sizeof(inbuf),
					.len[1] = 0 };

static int put_chars(u32 vtermno, const char *buf, int count)
{
	struct lguest_dma dma;

	/* FIXME: what if it's over a page boundary? */
	dma.len[0] = count;
	dma.len[1] = 0;
	dma.addr[0] = __pa(buf);

	lguest_send_dma(LGUEST_CONSOLE_DMA_KEY, &dma);
	return count;
}

static int get_chars(u32 vtermno, char *buf, int count)
{
	static int cons_offset;

	if (!cons_input.used_len)
		return 0;

	if (cons_input.used_len - cons_offset < count)
		count = cons_input.used_len - cons_offset;

	memcpy(buf, inbuf + cons_offset, count);
	cons_offset += count;
	if (cons_offset == cons_input.used_len) {
		cons_offset = 0;
		cons_input.used_len = 0;
	}
	return count;
}

static struct hv_ops lguest_cons = {
	.get_chars = get_chars,
	.put_chars = put_chars,
};

static int __init cons_init(void)
{
	if (strcmp(paravirt_ops.name, "lguest") != 0)
		return 0;

	return hvc_instantiate(0, 0, &lguest_cons);
}
console_initcall(cons_init);

static int lguestcons_probe(struct lguest_device *lgdev)
{
	int err;

	lgdev->private = hvc_alloc(0, lgdev_irq(lgdev), &lguest_cons, 256);
	if (IS_ERR(lgdev->private))
		return PTR_ERR(lgdev->private);

	err = lguest_bind_dma(LGUEST_CONSOLE_DMA_KEY, &cons_input, 1,
			      lgdev_irq(lgdev));
	if (err)
		printk("lguest console: failed to bind buffer.\n");
	return err;
}

static struct lguest_driver lguestcons_drv = {
	.name = "lguestcons",
	.owner = THIS_MODULE,
	.device_type = LGUEST_DEVICE_T_CONSOLE,
	.probe = lguestcons_probe,
};

static int __init hvc_lguest_init(void)
{
	return register_lguest_driver(&lguestcons_drv);
}
module_init(hvc_lguest_init);