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early_printk.c

/*
 * allow a console to be used for early printk
 * derived from arch/x86/kernel/early_printk.c
 *
 * Copyright 2007-2009 Analog Devices Inc.
 *
 * Licensed under the GPL-2
 */

#include <linux/kernel.h>
#include <linux/init.h>
#include <linux/serial_core.h>
#include <linux/console.h>
#include <linux/string.h>
#include <linux/reboot.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
#ifdef CONFIG_BFIN_JTAG_COMM
extern struct console *bfin_jc_early_init(void);
#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 |= CS6;
            break;
      case 7:
            cflag |= CS7;
            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_BFIN_JTAG_COMM
      /* Check for Blackfin JTAG */
      if (!strncmp(buf, "jtag", 4)) {
            buf += 4;
            early_console = bfin_jc_early_init();
      }
#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)
{
      u32 evt;
      SSYNC();

      /*
       * This starts up the shadow buffer, incase anything crashes before
       * setup arch
       */
      mark_shadow_error();
      early_shadow_puts(linux_banner);
      early_shadow_stamp();

      if (CPUID != bfin_cpuid()) {
            early_shadow_puts("Running on wrong machine type, expected");
            early_shadow_reg(CPUID, 16);
            early_shadow_puts(", but running on");
            early_shadow_reg(bfin_cpuid(), 16);
            early_shadow_puts("\n");
      }

      /* cannot program in software:
       * evt0 - emulation (jtag)
       * evt1 - reset
       */
      for (evt = EVT2; evt <= EVT15; evt += 4)
            bfin_write32(evt, early_trap);
      CSYNC();

      /* Set all the return from interrupt, 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));

}

__attribute__((__noreturn__))
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 (but only if we are running on the processor we think
       * we are compiled for - otherwise we write to MMRs that don't exist,
       * and cause other problems. Nothing comes out the UART, but it does
       * end up in the __buf_log.
       */
      if (likely(early_console == NULL) && CPUID == bfin_cpuid())
            setup_early_printk(DEFAULT_EARLY_PORT);

      if (!shadow_console_enabled()) {
            /* crap - we crashed before setup_arch() */
            early_shadow_puts("panic before setup_arch\n");
            early_shadow_puts("IPEND:");
            early_shadow_reg(fp->ipend, 16);
            if (fp->seqstat & SEQSTAT_EXCAUSE) {
                  early_shadow_puts("\nEXCAUSE:");
                  early_shadow_reg(fp->seqstat & SEQSTAT_EXCAUSE, 8);
            }
            if (fp->seqstat & SEQSTAT_HWERRCAUSE) {
                  early_shadow_puts("\nHWERRCAUSE:");
                  early_shadow_reg(
                        (fp->seqstat & SEQSTAT_HWERRCAUSE) >> 14, 8);
            }
            early_shadow_puts("\nErr @");
            if (fp->ipend & EVT_EVX)
                  early_shadow_reg(fp->retx, 32);
            else
                  early_shadow_reg(fp->pc, 32);
#ifdef CONFIG_DEBUG_BFIN_HWTRACE_ON
            early_shadow_puts("\nTrace:");
            if (likely(bfin_read_TBUFSTAT() & TBUFCNT)) {
                  while (bfin_read_TBUFSTAT() & TBUFCNT) {
                        early_shadow_puts("\nT  :");
                        early_shadow_reg(bfin_read_TBUF(), 32);
                        early_shadow_puts("\n S :");
                        early_shadow_reg(bfin_read_TBUF(), 32);
                  }
            }
#endif
            early_shadow_puts("\nUse bfin-elf-addr2line to determine "
                  "function names\n");
            /*
             * We should panic(), but we can't - since panic calls printk,
             * and printk uses memcpy.
             * we want to reboot, but if the machine type is different,
             * can't due to machine specific reboot sequences
             */
            if (CPUID == bfin_cpuid()) {
                  early_shadow_puts("Trying to restart\n");
                  machine_restart("");
            }

            early_shadow_puts("Halting, since it is not safe to restart\n");
            while (1)
                  asm volatile ("EMUEXCPT; IDLE;\n");

      } else {
            printk(KERN_EMERG "Early panic\n");
            show_regs(fp);
            dump_bfin_trace_buffer();
      }

      panic("Died early");
}

early_param("earlyprintk", setup_early_printk);

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