aboutsummaryrefslogtreecommitdiffstats
path: root/drivers/char/hvc_dcc.c
blob: 6470f63deb4b29f2ee5a29136ba351ce7fe86e7f (plain) (blame)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
/* Copyright (c) 2010, Code Aurora Forum. 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.
 *
 * 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., 51 Franklin Street, Fifth Floor, Boston, MA
 * 02110-1301, USA.
 */

#include <linux/console.h>
#include <linux/delay.h>
#include <linux/err.h>
#include <linux/init.h>
#include <linux/moduleparam.h>
#include <linux/types.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 inline u32 __dcc_getstatus(void)
{
	u32 __ret;

	asm("mrc p14, 0, %0, c0, c1, 0	@ read comms ctrl reg"
		: "=r" (__ret) : : "cc");

	return __ret;
}


#if defined(CONFIG_CPU_V7)
static inline char __dcc_getchar(void)
{
	char __c;

	asm("get_wait:	mrc p14, 0, pc, c0, c1, 0                          \n\
			bne get_wait                                       \n\
			mrc p14, 0, %0, c0, c5, 0	@ read comms data reg"
		: "=r" (__c) : : "cc");

	return __c;
}
#else
static inline char __dcc_getchar(void)
{
	char __c;

	asm("mrc p14, 0, %0, c0, c5, 0	@ read comms data reg"
		: "=r" (__c));

	return __c;
}
#endif

#if defined(CONFIG_CPU_V7)
static inline void __dcc_putchar(char c)
{
	asm("put_wait:	mrc p14, 0, pc, c0, c1, 0                 \n\
			bcs put_wait                              \n\
			mcr p14, 0, %0, c0, c5, 0                   "
	: : "r" (c) : "cc");
}
#else
static inline void __dcc_putchar(char c)
{
	asm("mcr p14, 0, %0, c0, c5, 0	@ write a char"
		: /* no output register */
		: "r" (c));
}
#endif

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((char)(buf[i] & 0xFF));
	}

	return count;
}

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

	for (i = 0; i < count; ++i) {
		int c = -1;

		if (__dcc_getstatus() & DCC_STATUS_RX)
			c = __dcc_getchar();
		if (c < 0)
			break;
		buf[i] = c;
	}

	return i;
}

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)
{
	hvc_instantiate(0, 0, &hvc_dcc_get_put_ops);
	return 0;
}
console_initcall(hvc_dcc_console_init);

static int __init hvc_dcc_init(void)
{
	hvc_alloc(0, 0, &hvc_dcc_get_put_ops, 128);
	return 0;
}
device_initcall(hvc_dcc_init);