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 
23 void *gdb_vbr_vector = NULL;
24 
sh_bios_call(long func,long arg0,long arg1,long arg2,long arg3)25 static 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 
sh_bios_console_write(const char * buf,unsigned int len)43 void 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 
sh_bios_gdb_detach(void)48 void sh_bios_gdb_detach(void)
49 {
50 	sh_bios_call(BIOS_CALL_GDB_DETACH, 0, 0, 0, 0);
51 }
52 EXPORT_SYMBOL_GPL(sh_bios_gdb_detach);
53 
sh_bios_get_node_addr(unsigned char * node_addr)54 void 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 }
58 EXPORT_SYMBOL_GPL(sh_bios_get_node_addr);
59 
sh_bios_shutdown(unsigned int how)60 void 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  */
sh_bios_vbr_init(void)70 void 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  */
sh_bios_vbr_reload(void)93 void 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  */
sh_console_write(struct console * co,const char * s,unsigned count)108 static 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  */
sh_console_setup(struct console * co,char * options)120 static 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 
137 static 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 
setup_early_printk(char * buf)145 static 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 }
168 early_param("earlyprintk", setup_early_printk);
169 #endif
170