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
7 * Description: allow a console to be used for early printk
10 * Copyright 2004-2007 Analog Devices Inc.
12 * Bugs: Enter bugs at http://blackfin.uclinux.org/
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.
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.
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 <linux/reboot.h>
31 #include <asm/blackfin.h>
32 #include <asm/irq_handler.h>
33 #include <asm/early_printk.h>
35 #ifdef CONFIG_SERIAL_BFIN
36 extern struct console *bfin_earlyserial_init(unsigned int port,
39 #ifdef CONFIG_BFIN_JTAG_COMM
40 extern struct console *bfin_jc_early_init(void);
43 static struct console *early_console;
46 #define DEFAULT_PORT 0
47 #define DEFAULT_CFLAG CS8|B57600
49 /* Default console for early crashes */
50 #define DEFAULT_EARLY_PORT "serial,uart0,57600"
52 #ifdef CONFIG_SERIAL_CORE
53 /* What should get here is "0,57600" */
54 static struct console * __init earlyserial_init(char *buf)
58 unsigned int serial_port = DEFAULT_PORT;
59 unsigned int cflag = DEFAULT_CFLAG;
61 serial_port = simple_strtoul(buf, &buf, 10);
65 baud = simple_strtoul(buf, &buf, 10);
103 bit = simple_strtoul(buf, &buf, 10);
118 #ifdef CONFIG_SERIAL_BFIN
119 return bfin_earlyserial_init(serial_port, cflag);
127 int __init setup_early_printk(char *buf)
130 /* Crashing in here would be really bad, so check both the var
131 and the pointer before we start using it
139 if (early_console != NULL)
142 #ifdef CONFIG_SERIAL_BFIN
143 /* Check for Blackfin Serial */
144 if (!strncmp(buf, "serial,uart", 11)) {
146 early_console = earlyserial_init(buf);
150 #ifdef CONFIG_BFIN_JTAG_COMM
151 /* Check for Blackfin JTAG */
152 if (!strncmp(buf, "jtag", 4)) {
154 early_console = bfin_jc_early_init();
159 /* TODO: add framebuffer console support */
162 if (likely(early_console)) {
163 early_console->flags |= CON_BOOT;
165 register_console(early_console);
166 printk(KERN_INFO "early printk enabled on %s%d\n",
168 early_console->index);
175 * Set up a temporary Event Vector Table, so if something bad happens before
176 * the kernel is fully started, it doesn't vector off into somewhere we don't
180 asmlinkage void __init init_early_exception_vectors(void)
186 * This starts up the shadow buffer, incase anything crashes before
190 early_shadow_puts(linux_banner);
191 early_shadow_stamp();
193 if (CPUID != bfin_cpuid()) {
194 early_shadow_puts("Running on wrong machine type, expected");
195 early_shadow_reg(CPUID, 16);
196 early_shadow_puts(", but running on");
197 early_shadow_reg(bfin_cpuid(), 16);
198 early_shadow_puts("\n");
201 /* cannot program in software:
202 * evt0 - emulation (jtag)
205 for (evt = EVT2; evt <= EVT15; evt += 4)
206 bfin_write32(evt, early_trap);
209 /* Set all the return from interrupt, exception, NMI to a known place
210 * so if we do a RETI, RETX or RETN by mistake - we go somewhere known
211 * Note - don't change RETS - we are in a subroutine, or
212 * RETE - since it might screw up if emulator is attached
214 asm("\tRETI = %0; RETX = %0; RETN = %0;\n"
215 : : "p"(early_trap));
219 __attribute__((__noreturn__))
220 asmlinkage void __init early_trap_c(struct pt_regs *fp, void *retaddr)
222 /* This can happen before the uart is initialized, so initialize
223 * the UART now (but only if we are running on the processor we think
224 * we are compiled for - otherwise we write to MMRs that don't exist,
225 * and cause other problems. Nothing comes out the UART, but it does
226 * end up in the __buf_log.
228 if (likely(early_console == NULL) && CPUID == bfin_cpuid())
229 setup_early_printk(DEFAULT_EARLY_PORT);
231 if (!shadow_console_enabled()) {
232 /* crap - we crashed before setup_arch() */
233 early_shadow_puts("panic before setup_arch\n");
234 early_shadow_puts("IPEND:");
235 early_shadow_reg(fp->ipend, 16);
236 if (fp->seqstat & SEQSTAT_EXCAUSE) {
237 early_shadow_puts("\nEXCAUSE:");
238 early_shadow_reg(fp->seqstat & SEQSTAT_EXCAUSE, 8);
240 if (fp->seqstat & SEQSTAT_HWERRCAUSE) {
241 early_shadow_puts("\nHWERRCAUSE:");
243 (fp->seqstat & SEQSTAT_HWERRCAUSE) >> 14, 8);
245 early_shadow_puts("\nErr @");
246 if (fp->ipend & EVT_EVX)
247 early_shadow_reg(fp->retx, 32);
249 early_shadow_reg(fp->pc, 32);
250 #ifdef CONFIG_DEBUG_BFIN_HWTRACE_ON
251 early_shadow_puts("\nTrace:");
252 if (likely(bfin_read_TBUFSTAT() & TBUFCNT)) {
253 while (bfin_read_TBUFSTAT() & TBUFCNT) {
254 early_shadow_puts("\nT :");
255 early_shadow_reg(bfin_read_TBUF(), 32);
256 early_shadow_puts("\n S :");
257 early_shadow_reg(bfin_read_TBUF(), 32);
261 early_shadow_puts("\nUse bfin-elf-addr2line to determine "
264 * We should panic(), but we can't - since panic calls printk,
265 * and printk uses memcpy.
266 * we want to reboot, but if the machine type is different,
267 * can't due to machine specific reboot sequences
269 if (CPUID == bfin_cpuid()) {
270 early_shadow_puts("Trying to restart\n");
274 early_shadow_puts("Halting, since it is not safe to restart\n");
276 asm volatile ("EMUEXCPT; IDLE;\n");
279 printk(KERN_EMERG "Early panic\n");
281 dump_bfin_trace_buffer();
287 early_param("earlyprintk", setup_early_printk);