early_printk.c revision 54ebae7166275a618f0228138e67ff7d10a3b9d0 
1/*
2 * File:         arch/blackfin/kernel/early_printk.c
3 * Based on:     arch/x86_64/kernel/early_printk.c
4 * Author:       Robin Getz <rgetz@blackfin.uclinux.org
5 *
6 * Created:      14Aug2007
7 * Description:  allow a console to be used for early printk
8 *
9 * Modified:
10 *               Copyright 2004-2007 Analog Devices Inc.
11 *
12 * Bugs:         Enter bugs at http://blackfin.uclinux.org/
13 *
14 * This program is free software; you can redistribute it and/or modify
15 * it under the terms of the GNU General Public License as published by
16 * the Free Software Foundation; either version 2 of the License, or
17 * (at your option) any later version.
18 *
19 * This program is distributed in the hope that it will be useful,
20 * but WITHOUT ANY WARRANTY; without even the implied warranty of
21 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
22 * GNU General Public License for more details.
23 */
24
25#include <linux/kernel.h>
26#include <linux/init.h>
27#include <linux/serial_core.h>
28#include <linux/console.h>
29#include <linux/string.h>
30#include <asm/blackfin.h>
31#include <asm/irq_handler.h>
32#include <asm/early_printk.h>
33
34#ifdef CONFIG_SERIAL_BFIN
35extern struct console *bfin_earlyserial_init(unsigned int port,
36						unsigned int cflag);
37#endif
38#ifdef CONFIG_BFIN_JTAG_COMM
39extern struct console *bfin_jc_early_init(void);
40#endif
41
42static struct console *early_console;
43
44/* Default console */
45#define DEFAULT_PORT 0
46#define DEFAULT_CFLAG CS8|B57600
47
48/* Default console for early crashes */
49#define DEFAULT_EARLY_PORT "serial,uart0,57600"
50
51#ifdef CONFIG_SERIAL_CORE
52/* What should get here is "0,57600" */
53static struct console * __init earlyserial_init(char *buf)
54{
55	int baud, bit;
56	char parity;
57	unsigned int serial_port = DEFAULT_PORT;
58	unsigned int cflag = DEFAULT_CFLAG;
59
60	serial_port = simple_strtoul(buf, &buf, 10);
61	buf++;
62
63	cflag = 0;
64	baud = simple_strtoul(buf, &buf, 10);
65	switch (baud) {
66	case 1200:
67		cflag |= B1200;
68		break;
69	case 2400:
70		cflag |= B2400;
71		break;
72	case 4800:
73		cflag |= B4800;
74		break;
75	case 9600:
76		cflag |= B9600;
77		break;
78	case 19200:
79		cflag |= B19200;
80		break;
81	case 38400:
82		cflag |= B38400;
83		break;
84	case 115200:
85		cflag |= B115200;
86		break;
87	default:
88		cflag |= B57600;
89	}
90
91	parity = buf[0];
92	buf++;
93	switch (parity) {
94	case 'e':
95		cflag |= PARENB;
96		break;
97	case 'o':
98		cflag |= PARODD;
99		break;
100	}
101
102	bit = simple_strtoul(buf, &buf, 10);
103	switch (bit) {
104	case 5:
105		cflag |= CS5;
106		break;
107	case 6:
108		cflag |= CS6;
109		break;
110	case 7:
111		cflag |= CS7;
112		break;
113	default:
114		cflag |= CS8;
115	}
116
117#ifdef CONFIG_SERIAL_BFIN
118	return bfin_earlyserial_init(serial_port, cflag);
119#else
120	return NULL;
121#endif
122
123}
124#endif
125
126int __init setup_early_printk(char *buf)
127{
128
129	/* Crashing in here would be really bad, so check both the var
130	   and the pointer before we start using it
131	 */
132	if (!buf)
133		return 0;
134
135	if (!*buf)
136		return 0;
137
138	if (early_console != NULL)
139		return 0;
140
141#ifdef CONFIG_SERIAL_BFIN
142	/* Check for Blackfin Serial */
143	if (!strncmp(buf, "serial,uart", 11)) {
144		buf += 11;
145		early_console = earlyserial_init(buf);
146	}
147#endif
148
149#ifdef CONFIG_BFIN_JTAG_COMM
150	/* Check for Blackfin JTAG */
151	if (!strncmp(buf, "jtag", 4)) {
152		buf += 4;
153		early_console = bfin_jc_early_init();
154	}
155#endif
156
157#ifdef CONFIG_FB
158		/* TODO: add framebuffer console support */
159#endif
160
161	if (likely(early_console)) {
162		early_console->flags |= CON_BOOT;
163
164		register_console(early_console);
165		printk(KERN_INFO "early printk enabled on %s%d\n",
166			early_console->name,
167			early_console->index);
168	}
169
170	return 0;
171}
172
173/*
174 * Set up a temporary Event Vector Table, so if something bad happens before
175 * the kernel is fully started, it doesn't vector off into somewhere we don't
176 * know
177 */
178
179asmlinkage void __init init_early_exception_vectors(void)
180{
181	u32 evt;
182	SSYNC();
183
184	/* cannot program in software:
185	 * evt0 - emulation (jtag)
186	 * evt1 - reset
187	 */
188	for (evt = EVT2; evt <= EVT15; evt += 4)
189		bfin_write32(evt, early_trap);
190	CSYNC();
191
192	/* Set all the return from interrupt, exception, NMI to a known place
193	 * so if we do a RETI, RETX or RETN by mistake - we go somewhere known
194	 * Note - don't change RETS - we are in a subroutine, or
195	 * RETE - since it might screw up if emulator is attached
196	 */
197	asm("\tRETI = %0; RETX = %0; RETN = %0;\n"
198		: : "p"(early_trap));
199
200}
201
202asmlinkage void __init early_trap_c(struct pt_regs *fp, void *retaddr)
203{
204	/* This can happen before the uart is initialized, so initialize
205	 * the UART now (but only if we are running on the processor we think
206	 * we are compiled for - otherwise we write to MMRs that don't exist,
207	 * and cause other problems. Nothing comes out the UART, but it does
208	 * end up in the __buf_log.
209	 */
210	if (likely(early_console == NULL) && CPUID == bfin_cpuid())
211		setup_early_printk(DEFAULT_EARLY_PORT);
212
213	printk(KERN_EMERG "Early panic\n");
214	dump_bfin_mem(fp);
215	show_regs(fp);
216	dump_bfin_trace_buffer();
217
218	panic("Died early");
219}
220
221early_param("earlyprintk", setup_early_printk);
222