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1// SPDX-License-Identifier: GPL-2.0
2/* Copyright (c) 2010, 2014 The Linux Foundation. All rights reserved. */
3
4#include <linux/console.h>
5#include <linux/init.h>
6#include <linux/serial.h>
7#include <linux/serial_core.h>
8
9#include <asm/dcc.h>
10#include <asm/processor.h>
11
12#include "hvc_console.h"
13
14/* DCC Status Bits */
15#define DCC_STATUS_RX (1 << 30)
16#define DCC_STATUS_TX (1 << 29)
17
18static void dcc_uart_console_putchar(struct uart_port *port, int ch)
19{
20 while (__dcc_getstatus() & DCC_STATUS_TX)
21 cpu_relax();
22
23 __dcc_putchar(ch);
24}
25
26static void dcc_early_write(struct console *con, const char *s, unsigned n)
27{
28 struct earlycon_device *dev = con->data;
29
30 uart_console_write(&dev->port, s, n, dcc_uart_console_putchar);
31}
32
33static int __init dcc_early_console_setup(struct earlycon_device *device,
34 const char *opt)
35{
36 device->con->write = dcc_early_write;
37
38 return 0;
39}
40
41EARLYCON_DECLARE(dcc, dcc_early_console_setup);
42
43static int hvc_dcc_put_chars(uint32_t vt, const char *buf, int count)
44{
45 int i;
46
47 for (i = 0; i < count; i++) {
48 while (__dcc_getstatus() & DCC_STATUS_TX)
49 cpu_relax();
50
51 __dcc_putchar(buf[i]);
52 }
53
54 return count;
55}
56
57static int hvc_dcc_get_chars(uint32_t vt, char *buf, int count)
58{
59 int i;
60
61 for (i = 0; i < count; ++i)
62 if (__dcc_getstatus() & DCC_STATUS_RX)
63 buf[i] = __dcc_getchar();
64 else
65 break;
66
67 return i;
68}
69
70static bool hvc_dcc_check(void)
71{
72 unsigned long time = jiffies + (HZ / 10);
73
74 /* Write a test character to check if it is handled */
75 __dcc_putchar('\n');
76
77 while (time_is_after_jiffies(time)) {
78 if (!(__dcc_getstatus() & DCC_STATUS_TX))
79 return true;
80 }
81
82 return false;
83}
84
85static const struct hv_ops hvc_dcc_get_put_ops = {
86 .get_chars = hvc_dcc_get_chars,
87 .put_chars = hvc_dcc_put_chars,
88};
89
90static int __init hvc_dcc_console_init(void)
91{
92 int ret;
93
94 if (!hvc_dcc_check())
95 return -ENODEV;
96
97 /* Returns -1 if error */
98 ret = hvc_instantiate(0, 0, &hvc_dcc_get_put_ops);
99
100 return ret < 0 ? -ENODEV : 0;
101}
102console_initcall(hvc_dcc_console_init);
103
104static int __init hvc_dcc_init(void)
105{
106 struct hvc_struct *p;
107
108 if (!hvc_dcc_check())
109 return -ENODEV;
110
111 p = hvc_alloc(0, 0, &hvc_dcc_get_put_ops, 128);
112
113 return PTR_ERR_OR_ZERO(p);
114}
115device_initcall(hvc_dcc_init);
1/* Copyright (c) 2010, Code Aurora Forum. All rights reserved.
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.
11 *
12 * You should have received a copy of the GNU General Public License
13 * along with this program; if not, write to the Free Software
14 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
15 * 02110-1301, USA.
16 */
17
18#include <linux/console.h>
19#include <linux/delay.h>
20#include <linux/err.h>
21#include <linux/init.h>
22#include <linux/moduleparam.h>
23#include <linux/types.h>
24
25#include <asm/processor.h>
26
27#include "hvc_console.h"
28
29/* DCC Status Bits */
30#define DCC_STATUS_RX (1 << 30)
31#define DCC_STATUS_TX (1 << 29)
32
33static inline u32 __dcc_getstatus(void)
34{
35 u32 __ret;
36 asm volatile("mrc p14, 0, %0, c0, c1, 0 @ read comms ctrl reg"
37 : "=r" (__ret) : : "cc");
38
39 return __ret;
40}
41
42
43static inline char __dcc_getchar(void)
44{
45 char __c;
46
47 asm volatile("mrc p14, 0, %0, c0, c5, 0 @ read comms data reg"
48 : "=r" (__c));
49 isb();
50
51 return __c;
52}
53
54static inline void __dcc_putchar(char c)
55{
56 asm volatile("mcr p14, 0, %0, c0, c5, 0 @ write a char"
57 : /* no output register */
58 : "r" (c));
59 isb();
60}
61
62static int hvc_dcc_put_chars(uint32_t vt, const char *buf, int count)
63{
64 int i;
65
66 for (i = 0; i < count; i++) {
67 while (__dcc_getstatus() & DCC_STATUS_TX)
68 cpu_relax();
69
70 __dcc_putchar(buf[i]);
71 }
72
73 return count;
74}
75
76static int hvc_dcc_get_chars(uint32_t vt, char *buf, int count)
77{
78 int i;
79
80 for (i = 0; i < count; ++i)
81 if (__dcc_getstatus() & DCC_STATUS_RX)
82 buf[i] = __dcc_getchar();
83 else
84 break;
85
86 return i;
87}
88
89static bool hvc_dcc_check(void)
90{
91 unsigned long time = jiffies + (HZ / 10);
92
93 /* Write a test character to check if it is handled */
94 __dcc_putchar('\n');
95
96 while (time_is_after_jiffies(time)) {
97 if (!(__dcc_getstatus() & DCC_STATUS_TX))
98 return true;
99 }
100
101 return false;
102}
103
104static const struct hv_ops hvc_dcc_get_put_ops = {
105 .get_chars = hvc_dcc_get_chars,
106 .put_chars = hvc_dcc_put_chars,
107};
108
109static int __init hvc_dcc_console_init(void)
110{
111 if (!hvc_dcc_check())
112 return -ENODEV;
113
114 hvc_instantiate(0, 0, &hvc_dcc_get_put_ops);
115 return 0;
116}
117console_initcall(hvc_dcc_console_init);
118
119static int __init hvc_dcc_init(void)
120{
121 if (!hvc_dcc_check())
122 return -ENODEV;
123
124 hvc_alloc(0, 0, &hvc_dcc_get_put_ops, 128);
125 return 0;
126}
127device_initcall(hvc_dcc_init);