early_printk.c

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/*
 * 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);