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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