[linux-2.6-block.git] / drivers / tty / hvc / hvc_dcc.c

/* Copyright (c) 2010, 2014 The Linux Foundation. All rights reserved.
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 and
 * only version 2 as published by the Free Software Foundation.
 *
 * 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.
 */

#include <linux/init.h>

#include <asm/dcc.h>
#include <asm/processor.h>

#include "hvc_console.h"

/* DCC Status Bits */
#define DCC_STATUS_RX		(1 << 30)
#define DCC_STATUS_TX		(1 << 29)

static int hvc_dcc_put_chars(uint32_t vt, const char *buf, int count)
{
	int i;

	for (i = 0; i < count; i++) {
		while (__dcc_getstatus() & DCC_STATUS_TX)
			cpu_relax();

		__dcc_putchar(buf[i]);
	}

	return count;
}

static int hvc_dcc_get_chars(uint32_t vt, char *buf, int count)
{
	int i;

	for (i = 0; i < count; ++i)
		if (__dcc_getstatus() & DCC_STATUS_RX)
			buf[i] = __dcc_getchar();
		else
			break;

	return i;
}

static bool hvc_dcc_check(void)
{
	unsigned long time = jiffies + (HZ / 10);

	/* Write a test character to check if it is handled */
	__dcc_putchar('\n');

	while (time_is_after_jiffies(time)) {
		if (!(__dcc_getstatus() & DCC_STATUS_TX))
			return true;
	}

	return false;
}

static const struct hv_ops hvc_dcc_get_put_ops = {
	.get_chars = hvc_dcc_get_chars,
	.put_chars = hvc_dcc_put_chars,
};

static int __init hvc_dcc_console_init(void)
{
	int ret;

	if (!hvc_dcc_check())
		return -ENODEV;

	/* Returns -1 if error */
	ret = hvc_instantiate(0, 0, &hvc_dcc_get_put_ops);

	return ret < 0 ? -ENODEV : 0;
}
console_initcall(hvc_dcc_console_init);

static int __init hvc_dcc_init(void)
{
	struct hvc_struct *p;

	if (!hvc_dcc_check())
		return -ENODEV;

	p = hvc_alloc(0, 0, &hvc_dcc_get_put_ops, 128);

	return PTR_ERR_OR_ZERO(p);
}
device_initcall(hvc_dcc_init);
Commit	Line	Data
4061f498	1	/* Copyright (c) 2010, 2014 The Linux Foundation. All rights reserved.
16c63f8e DW	2	*
	3	* This program is free software; you can redistribute it and/or modify
	4	* it under the terms of the GNU General Public License version 2 and
	5	* only version 2 as published by the Free Software Foundation.
	6	*
	7	* This program is distributed in the hope that it will be useful,
	8	* but WITHOUT ANY WARRANTY; without even the implied warranty of
	9	* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
	10	* GNU General Public License for more details.
16c63f8e DW	11	*/
16c63f8e DW	12
16c63f8e	13	#include <linux/init.h>
16c63f8e	14
4061f498	15	#include <asm/dcc.h>
16c63f8e DW	16	#include <asm/processor.h>
	17
	18	#include "hvc_console.h"
	19
	20	/* DCC Status Bits */
	21	#define DCC_STATUS_RX (1 << 30)
	22	#define DCC_STATUS_TX (1 << 29)
	23
16c63f8e DW	24	static int hvc_dcc_put_chars(uint32_t vt, const char *buf, int count)
	25	{
	26	int i;
	27
	28	for (i = 0; i < count; i++) {
	29	while (__dcc_getstatus() & DCC_STATUS_TX)
	30	cpu_relax();
	31
bf73bd35	32	__dcc_putchar(buf[i]);
16c63f8e DW	33	}
	34
	35	return count;
	36	}
	37
	38	static int hvc_dcc_get_chars(uint32_t vt, char *buf, int count)
	39	{
	40	int i;
	41
bf73bd35	42	for (i = 0; i < count; ++i)
16c63f8e	43	if (__dcc_getstatus() & DCC_STATUS_RX)
bf73bd35 SB	44	buf[i] = __dcc_getchar();
bf73bd35 SB	45	else
16c63f8e	46	break;
16c63f8e DW	47
	48	return i;
	49	}
	50
f377775d RH	51	static bool hvc_dcc_check(void)
	52	{
	53	unsigned long time = jiffies + (HZ / 10);
	54
	55	/* Write a test character to check if it is handled */
	56	__dcc_putchar('\n');
	57
	58	while (time_is_after_jiffies(time)) {
	59	if (!(__dcc_getstatus() & DCC_STATUS_TX))
	60	return true;
	61	}
	62
	63	return false;
	64	}
	65
16c63f8e DW	66	static const struct hv_ops hvc_dcc_get_put_ops = {
	67	.get_chars = hvc_dcc_get_chars,
	68	.put_chars = hvc_dcc_put_chars,
	69	};
	70
	71	static int __init hvc_dcc_console_init(void)
	72	{
3d270701 TT	73	int ret;
3d270701 TT	74
f377775d RH	75	if (!hvc_dcc_check())
	76	return -ENODEV;
	77
3d270701 TT	78	/* Returns -1 if error */
	79	ret = hvc_instantiate(0, 0, &hvc_dcc_get_put_ops);
	80
	81	return ret < 0 ? -ENODEV : 0;
16c63f8e DW	82	}
	83	console_initcall(hvc_dcc_console_init);
	84
	85	static int __init hvc_dcc_init(void)
	86	{
3d270701 TT	87	struct hvc_struct *p;
3d270701 TT	88
f377775d RH	89	if (!hvc_dcc_check())
	90	return -ENODEV;
	91
3d270701 TT	92	p = hvc_alloc(0, 0, &hvc_dcc_get_put_ops, 128);
	93
	94	return PTR_ERR_OR_ZERO(p);
16c63f8e DW	95	}
16c63f8e DW	96	device_initcall(hvc_dcc_init);