1// SPDX-License-Identifier: GPL-2.0
2/*
3 *  C interface for trapping into the standard LinuxSH BIOS.
4 *
5 *  Copyright (C) 2000 Greg Banks, Mitch Davis
6 *  Copyright (C) 1999, 2000  Niibe Yutaka
7 *  Copyright (C) 2002  M. R. Brown
8 *  Copyright (C) 2004 - 2010  Paul Mundt
9 */
10#include <linux/module.h>
11#include <linux/console.h>
12#include <linux/tty.h>
13#include <linux/init.h>
14#include <linux/io.h>
15#include <linux/delay.h>
16#include <asm/sh_bios.h>
17
18#define BIOS_CALL_CONSOLE_WRITE		0
19#define BIOS_CALL_ETH_NODE_ADDR		10
20#define BIOS_CALL_SHUTDOWN		11
21#define BIOS_CALL_GDB_DETACH		0xff
22
23void *gdb_vbr_vector = NULL;
24
25static inline long sh_bios_call(long func, long arg0, long arg1, long arg2,
26				    long arg3)
27{
28	register long r0 __asm__("r0") = func;
29	register long r4 __asm__("r4") = arg0;
30	register long r5 __asm__("r5") = arg1;
31	register long r6 __asm__("r6") = arg2;
32	register long r7 __asm__("r7") = arg3;
33
34	if (!gdb_vbr_vector)
35		return -ENOSYS;
36
37	__asm__ __volatile__("trapa	#0x3f":"=z"(r0)
38			     :"0"(r0), "r"(r4), "r"(r5), "r"(r6), "r"(r7)
39			     :"memory");
40	return r0;
41}
42
43void sh_bios_console_write(const char *buf, unsigned int len)
44{
45	sh_bios_call(BIOS_CALL_CONSOLE_WRITE, (long)buf, (long)len, 0, 0);
46}
47
48void sh_bios_gdb_detach(void)
49{
50	sh_bios_call(BIOS_CALL_GDB_DETACH, 0, 0, 0, 0);
51}
52EXPORT_SYMBOL_GPL(sh_bios_gdb_detach);
53
54void sh_bios_get_node_addr(unsigned char *node_addr)
55{
56	sh_bios_call(BIOS_CALL_ETH_NODE_ADDR, 0, (long)node_addr, 0, 0);
57}
58EXPORT_SYMBOL_GPL(sh_bios_get_node_addr);
59
60void sh_bios_shutdown(unsigned int how)
61{
62	sh_bios_call(BIOS_CALL_SHUTDOWN, how, 0, 0, 0);
63}
64
65/*
66 * Read the old value of the VBR register to initialise the vector
67 * through which debug and BIOS traps are delegated by the Linux trap
68 * handler.
69 */
70void sh_bios_vbr_init(void)
71{
72	unsigned long vbr;
73
74	if (unlikely(gdb_vbr_vector))
75		return;
76
77	__asm__ __volatile__ ("stc vbr, %0" : "=r" (vbr));
78
79	if (vbr) {
80		gdb_vbr_vector = (void *)(vbr + 0x100);
81		printk(KERN_NOTICE "Setting GDB trap vector to %p\n",
82		       gdb_vbr_vector);
83	} else
84		printk(KERN_NOTICE "SH-BIOS not detected\n");
85}
86
87/**
88 * sh_bios_vbr_reload - Re-load the system VBR from the BIOS vector.
89 *
90 * This can be used by save/restore code to reinitialize the system VBR
91 * from the fixed BIOS VBR. A no-op if no BIOS VBR is known.
92 */
93void sh_bios_vbr_reload(void)
94{
95	if (gdb_vbr_vector)
96		__asm__ __volatile__ (
97			"ldc %0, vbr"
98			:
99			: "r" (((unsigned long) gdb_vbr_vector) - 0x100)
100			: "memory"
101		);
102}
103
104#ifdef CONFIG_EARLY_PRINTK
105/*
106 *	Print a string through the BIOS
107 */
108static void sh_console_write(struct console *co, const char *s,
109				 unsigned count)
110{
111	sh_bios_console_write(s, count);
112}
113
114/*
115 *	Setup initial baud/bits/parity. We do two things here:
116 *	- construct a cflag setting for the first rs_open()
117 *	- initialize the serial port
118 *	Return non-zero if we didn't find a serial port.
119 */
120static int __init sh_console_setup(struct console *co, char *options)
121{
122	int	cflag = CREAD | HUPCL | CLOCAL;
123
124	/*
125	 *	Now construct a cflag setting.
126	 *	TODO: this is a totally bogus cflag, as we have
127	 *	no idea what serial settings the BIOS is using, or
128	 *	even if its using the serial port at all.
129	 */
130	cflag |= B115200 | CS8 | /*no parity*/0;
131
132	co->cflag = cflag;
133
134	return 0;
135}
136
137static struct console bios_console = {
138	.name		= "bios",
139	.write		= sh_console_write,
140	.setup		= sh_console_setup,
141	.flags		= CON_PRINTBUFFER,
142	.index		= -1,
143};
144
145static int __init setup_early_printk(char *buf)
146{
147	int keep_early = 0;
148
149	if (!buf)
150		return 0;
151
152	if (strstr(buf, "keep"))
153		keep_early = 1;
154
155	if (!strncmp(buf, "bios", 4))
156		early_console = &bios_console;
157
158	if (likely(early_console)) {
159		if (keep_early)
160			early_console->flags &= ~CON_BOOT;
161		else
162			early_console->flags |= CON_BOOT;
163		register_console(early_console);
164	}
165
166	return 0;
167}
168early_param("earlyprintk", setup_early_printk);
169#endif
170