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 inline int hvc_rtas_write_console(uint32_t vtermno, const char *buf,
35		int count)
36{
37	int 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 int hvc_rtas_read_console(uint32_t vtermno, char *buf, int count)
48{
49	int i, c;
50
51	for (i = 0; i < count; i++) {
52		if (rtas_call(rtascons_get_char_token, 0, 2, &c))
53			break;
54
55		buf[i] = c;
56	}
57
58	return i;
59}
60
61static const struct hv_ops hvc_rtas_get_put_ops = {
62	.get_chars = hvc_rtas_read_console,
63	.put_chars = hvc_rtas_write_console,
64};
65
66static int __init hvc_rtas_init(void)
67{
68	struct hvc_struct *hp;
69
70	if (rtascons_put_char_token == RTAS_UNKNOWN_SERVICE)
71		rtascons_put_char_token = rtas_token("put-term-char");
72	if (rtascons_put_char_token == RTAS_UNKNOWN_SERVICE)
73		return -EIO;
74
75	if (rtascons_get_char_token == RTAS_UNKNOWN_SERVICE)
76		rtascons_get_char_token = rtas_token("get-term-char");
77	if (rtascons_get_char_token == RTAS_UNKNOWN_SERVICE)
78		return -EIO;
79
80	BUG_ON(hvc_rtas_dev);
81
82	/* Allocate an hvc_struct for the console device we instantiated
83	 * earlier.  Save off hp so that we can return it on exit */
84	hp = hvc_alloc(hvc_rtas_cookie, 0, &hvc_rtas_get_put_ops, 16);
85	if (IS_ERR(hp))
86		return PTR_ERR(hp);
87
88	hvc_rtas_dev = hp;
89
90	return 0;
91}
92device_initcall(hvc_rtas_init);
93
94/* This will happen prior to module init.  There is no tty at this time? */
95static int __init hvc_rtas_console_init(void)
96{
97	rtascons_put_char_token = rtas_token("put-term-char");
98	if (rtascons_put_char_token == RTAS_UNKNOWN_SERVICE)
99		return -EIO;
100
101	rtascons_get_char_token = rtas_token("get-term-char");
102	if (rtascons_get_char_token == RTAS_UNKNOWN_SERVICE)
103		return -EIO;
104
105	hvc_instantiate(hvc_rtas_cookie, 0, &hvc_rtas_get_put_ops);
106	add_preferred_console("hvc", 0, NULL);
107
108	return 0;
109}
110console_initcall(hvc_rtas_console_init);
111