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
29 static struct hvc_struct *hvc_rtas_dev;
30 
31 static int rtascons_put_char_token = RTAS_UNKNOWN_SERVICE;
32 static int rtascons_get_char_token = RTAS_UNKNOWN_SERVICE;
33 
hvc_rtas_write_console(uint32_t vtermno,const u8 * buf,size_t count)34 static 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 
hvc_rtas_read_console(uint32_t vtermno,u8 * buf,size_t count)47 static 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 
62 static 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 
hvc_rtas_init(void)67 static 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, 0, &hvc_rtas_get_put_ops, 16);
86 	if (IS_ERR(hp))
87 		return PTR_ERR(hp);
88 
89 	hvc_rtas_dev = hp;
90 
91 	return 0;
92 }
93 device_initcall(hvc_rtas_init);
94 
95 /* This will happen prior to module init.  There is no tty at this time? */
hvc_rtas_console_init(void)96 static 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, 0, &hvc_rtas_get_put_ops);
107 	add_preferred_console("hvc", 0, NULL);
108 
109 	return 0;
110 }
111 console_initcall(hvc_rtas_console_init);
112