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early_printk.c

/*
 * File:         arch/blackfin/kernel/early_printk.c
 * Based on:     arch/x86_64/kernel/early_printk.c
 * Author:       Robin Getz <rgetz@blackfin.uclinux.org
 *
 * Created:      14Aug2007
 * Description:  allow a console to be used for early printk
 *
 * Modified:
 *               Copyright 2004-2007 Analog Devices Inc.
 *
 * Bugs:         Enter bugs at http://blackfin.uclinux.org/
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 */

#include <linux/kernel.h>
#include <linux/init.h>
#include <linux/serial_core.h>
#include <linux/console.h>
#include <linux/string.h>
#include <asm/blackfin.h>
#include <asm/irq_handler.h>
#include <asm/early_printk.h>

#ifdef CONFIG_SERIAL_BFIN
extern struct console *bfin_earlyserial_init(unsigned int port,
                                    unsigned int cflag);
#endif

static struct console *early_console;

/* Default console */
#define DEFAULT_PORT 0
#define DEFAULT_CFLAG CS8|B57600

/* Default console for early crashes */
#define DEFAULT_EARLY_PORT "serial,uart0,57600"

#ifdef CONFIG_SERIAL_CORE
/* What should get here is "0,57600" */
static struct console * __init earlyserial_init(char *buf)
{
      int baud, bit;
      char parity;
      unsigned int serial_port = DEFAULT_PORT;
      unsigned int cflag = DEFAULT_CFLAG;

      serial_port = simple_strtoul(buf, &buf, 10);
      buf++;

      cflag = 0;
      baud = simple_strtoul(buf, &buf, 10);
      switch (baud) {
      case 1200:
            cflag |= B1200;
            break;
      case 2400:
            cflag |= B2400;
            break;
      case 4800:
            cflag |= B4800;
            break;
      case 9600:
            cflag |= B9600;
            break;
      case 19200:
            cflag |= B19200;
            break;
      case 38400:
            cflag |= B38400;
            break;
      case 115200:
            cflag |= B115200;
            break;
      default:
            cflag |= B57600;
      }

      parity = buf[0];
      buf++;
      switch (parity) {
      case 'e':
            cflag |= PARENB;
            break;
      case 'o':
            cflag |= PARODD;
            break;
      }

      bit = simple_strtoul(buf, &buf, 10);
      switch (bit) {
      case 5:
            cflag |= CS5;
            break;
      case 6:
            cflag |= CS5;
            break;
      case 7:
            cflag |= CS5;
            break;
      default:
            cflag |= CS8;
      }

#ifdef CONFIG_SERIAL_BFIN
      return bfin_earlyserial_init(serial_port, cflag);
#else
      return NULL;
#endif

}
#endif

int __init setup_early_printk(char *buf)
{

      /* Crashing in here would be really bad, so check both the var
         and the pointer before we start using it
       */
      if (!buf)
            return 0;

      if (!*buf)
            return 0;

      if (early_console != NULL)
            return 0;

#ifdef CONFIG_SERIAL_BFIN
      /* Check for Blackfin Serial */
      if (!strncmp(buf, "serial,uart", 11)) {
            buf += 11;
            early_console = earlyserial_init(buf);
      }
#endif
#ifdef CONFIG_FB
            /* TODO: add framebuffer console support */
#endif

      if (likely(early_console)) {
            early_console->flags |= CON_BOOT;

            register_console(early_console);
            printk(KERN_INFO "early printk enabled on %s%d\n",
                  early_console->name,
                  early_console->index);
      }

      return 0;
}

/*
 * Set up a temporary Event Vector Table, so if something bad happens before
 * the kernel is fully started, it doesn't vector off into somewhere we don't
 * know
 */

asmlinkage void __init init_early_exception_vectors(void)
{
      SSYNC();

      /* cannot program in software:
       * evt0 - emulation (jtag)
       * evt1 - reset
       */
      bfin_write_EVT2(early_trap);
      bfin_write_EVT3(early_trap);
      bfin_write_EVT5(early_trap);
      bfin_write_EVT6(early_trap);
      bfin_write_EVT7(early_trap);
      bfin_write_EVT8(early_trap);
      bfin_write_EVT9(early_trap);
      bfin_write_EVT10(early_trap);
      bfin_write_EVT11(early_trap);
      bfin_write_EVT12(early_trap);
      bfin_write_EVT13(early_trap);
      bfin_write_EVT14(early_trap);
      bfin_write_EVT15(early_trap);
      CSYNC();

      /* Set all the return from interupt, exception, NMI to a known place
       * so if we do a RETI, RETX or RETN by mistake - we go somewhere known
       * Note - don't change RETS - we are in a subroutine, or
       * RETE - since it might screw up if emulator is attached
       */
      asm("\tRETI = %0; RETX = %0; RETN = %0;\n"
            : : "p"(early_trap));

}

asmlinkage void __init early_trap_c(struct pt_regs *fp, void *retaddr)
{
      /* This can happen before the uart is initialized, so initialize
       * the UART now
       */
      if (likely(early_console == NULL))
            setup_early_printk(DEFAULT_EARLY_PORT);

      dump_bfin_mem((void *)fp->retx);
      show_regs(fp);
      dump_bfin_trace_buffer();

      panic("Died early");
}

early_param("earlyprintk", setup_early_printk);

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