1// SPDX-License-Identifier: GPL-2.0+
2/*
3 * IBM RTAS driver interface to hvc_console.c
4 *
5 * (C) Copyright IBM Corporation 2001-2005
6 * (C) Copyright Red Hat, Inc. 2005
7 *
8 * Author(s): Maximino Augilar <IBM STI Design Center>
9 * : Ryan S. Arnold <rsa@us.ibm.com>
10 * : Utz Bacher <utz.bacher@de.ibm.com>
11 * : David Woodhouse <dwmw2@infradead.org>
12 *
13 * inspired by drivers/char/hvc_console.c
14 * written by Anton Blanchard and Paul Mackerras
15 */
16
17#include <linux/console.h>
18#include <linux/delay.h>
19#include <linux/err.h>
20#include <linux/init.h>
21#include <linux/moduleparam.h>
22#include <linux/types.h>
23
24#include <asm/irq.h>
25#include <asm/rtas.h>
26#include "hvc_console.h"
27
28#define hvc_rtas_cookie 0x67781e15
29static struct hvc_struct *hvc_rtas_dev;
30
31static int rtascons_put_char_token = RTAS_UNKNOWN_SERVICE;
32static int rtascons_get_char_token = RTAS_UNKNOWN_SERVICE;
33
34static ssize_t hvc_rtas_write_console(uint32_t vtermno, const u8 *buf,
35 size_t count)
36{
37 size_t i;
38
39 for (i = 0; i < count; i++) {
40 if (rtas_call(rtascons_put_char_token, 1, 1, NULL, buf[i]))
41 break;
42 }
43
44 return i;
45}
46
47static ssize_t hvc_rtas_read_console(uint32_t vtermno, u8 *buf, size_t count)
48{
49 size_t i;
50 int c;
51
52 for (i = 0; i < count; i++) {
53 if (rtas_call(rtascons_get_char_token, 0, 2, &c))
54 break;
55
56 buf[i] = c;
57 }
58
59 return i;
60}
61
62static const struct hv_ops hvc_rtas_get_put_ops = {
63 .get_chars = hvc_rtas_read_console,
64 .put_chars = hvc_rtas_write_console,
65};
66
67static int __init hvc_rtas_init(void)
68{
69 struct hvc_struct *hp;
70
71 if (rtascons_put_char_token == RTAS_UNKNOWN_SERVICE)
72 rtascons_put_char_token = rtas_token("put-term-char");
73 if (rtascons_put_char_token == RTAS_UNKNOWN_SERVICE)
74 return -EIO;
75
76 if (rtascons_get_char_token == RTAS_UNKNOWN_SERVICE)
77 rtascons_get_char_token = rtas_token("get-term-char");
78 if (rtascons_get_char_token == RTAS_UNKNOWN_SERVICE)
79 return -EIO;
80
81 BUG_ON(hvc_rtas_dev);
82
83 /* Allocate an hvc_struct for the console device we instantiated
84 * earlier. Save off hp so that we can return it on exit */
85 hp = hvc_alloc(hvc_rtas_cookie, data: 0, ops: &hvc_rtas_get_put_ops, outbuf_size: 16);
86 if (IS_ERR(ptr: hp))
87 return PTR_ERR(ptr: hp);
88
89 hvc_rtas_dev = hp;
90
91 return 0;
92}
93device_initcall(hvc_rtas_init);
94
95/* This will happen prior to module init. There is no tty at this time? */
96static int __init hvc_rtas_console_init(void)
97{
98 rtascons_put_char_token = rtas_token("put-term-char");
99 if (rtascons_put_char_token == RTAS_UNKNOWN_SERVICE)
100 return -EIO;
101
102 rtascons_get_char_token = rtas_token("get-term-char");
103 if (rtascons_get_char_token == RTAS_UNKNOWN_SERVICE)
104 return -EIO;
105
106 hvc_instantiate(hvc_rtas_cookie, index: 0, ops: &hvc_rtas_get_put_ops);
107 add_preferred_console(name: "hvc", idx: 0, NULL);
108
109 return 0;
110}
111console_initcall(hvc_rtas_console_init);
112

source code of linux/drivers/tty/hvc/hvc_rtas.c