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    Subject[PATCH 20/60] microblaze_v4: early_printk support
    Date
    From: Michal Simek <monstr@monstr.eu>


    Signed-off-by: Michal Simek <monstr@monstr.eu>
    ---
    arch/microblaze/kernel/early_printk.c | 130 +++++++++++++++++++++++++++++++++
    1 files changed, 130 insertions(+), 0 deletions(-)
    create mode 100644 arch/microblaze/kernel/early_printk.c

    diff --git a/arch/microblaze/kernel/early_printk.c b/arch/microblaze/kernel/early_printk.c
    new file mode 100644
    index 0000000..6da0fd9
    --- /dev/null
    +++ b/arch/microblaze/kernel/early_printk.c
    @@ -0,0 +1,130 @@
    +/*
    + * Early printk support for Microblaze.
    + *
    + * Copyright (C) 2007-2008 Michal Simek <monstr@monstr.eu>
    + * Copyright (C) 2003-2006 Yasushi SHOJI <yashi@atmark-techno.com>
    + *
    + * This file is subject to the terms and conditions of the GNU General Public
    + * License. See the file "COPYING" in the main directory of this archive
    + * for more details.
    + */
    +
    +/* FIXME Once we got some system without uart light, we need to refactor */
    +
    +#include <linux/console.h>
    +#include <linux/kernel.h>
    +#include <linux/init.h>
    +#include <linux/string.h>
    +#include <linux/tty.h>
    +#include <asm/io.h>
    +#include <asm/processor.h>
    +#include <asm/fcntl.h>
    +#include <asm/setup.h>
    +
    +#ifdef CONFIG_EARLY_PRINTK
    +#define BASE_ADDR ((unsigned char *)CONFIG_EARLY_PRINTK_UARTLITE_ADDRESS)
    +
    +#define RX_FIFO BASE_ADDR
    +#define TX_FIFO ((unsigned long *)(BASE_ADDR + 4))
    +#define STATUS ((unsigned long *)(BASE_ADDR + 8))
    +#define CONTROL ((unsigned long *)(BASE_ADDR + 12))
    +
    +static void early_printk_putc(char c)
    +{
    + /*
    + * Limit how many times we'll spin waiting for TX FIFO status.
    + * This will prevent lockups if the base address is incorrectly
    + * set, or any other issue on the UARTLITE.
    + * This limit is pretty arbitrary, unless we are at about 10 baud
    + * we'll never timeout on a working UART.
    + */
    +
    + unsigned retries = 10000;
    + while (retries-- && (ioread32(STATUS) & (1<<3)))
    + ;
    +
    + /* Only attempt the iowrite if we didn't timeout */
    + if (retries)
    + iowrite32((c & 0xff), TX_FIFO);
    +}
    +
    +static void early_printk_write(struct console *unused,
    + const char *s, unsigned n)
    +{
    + while (*s && n-- > 0) {
    + early_printk_putc(*s);
    + if (*s == '\n')
    + early_printk_putc('\r');
    + s++;
    + }
    +}
    +
    +static struct console early_serial_console = {
    + .name = "earlyser",
    + .write = early_printk_write,
    + .flags = CON_PRINTBUFFER,
    + .index = -1,
    +};
    +
    +/* Direct interface for emergencies */
    +static struct console *early_console = &early_serial_console;
    +static int early_console_initialized;
    +
    +void early_printk(const char *fmt, ...)
    +{
    + char buf[512];
    + int n;
    + va_list ap;
    +
    + if (early_console_initialized) {
    + va_start(ap, fmt);
    + n = vscnprintf(buf, 512, fmt, ap);
    + early_console->write(early_console, buf, n);
    + va_end(ap);
    + }
    +}
    +
    +static int __initdata keep_early;
    +
    +int __init setup_early_printk(char *opt)
    +{
    + char *space;
    + char buf[256];
    +
    + if (early_console_initialized)
    + return 1;
    +
    + strlcpy(buf, opt, sizeof(buf));
    + space = strchr(buf, ' ');
    + if (space)
    + *space = 0;
    +
    + if (strstr(buf, "keep"))
    + keep_early = 1;
    +
    + early_console = &early_serial_console;
    + early_console_initialized = 1;
    + register_console(early_console);
    + return 0;
    +}
    +#if 0
    +static void __init disable_early_printk(void)
    +{
    + if (!early_console_initialized || !early_console)
    + return;
    + if (!keep_early) {
    + printk(KERN_INFO "disabling early console\n");
    + unregister_console(early_console);
    + early_console_initialized = 0;
    + } else
    + printk(KERN_INFO "keeping early console\n");
    +}
    +#endif
    +
    +__setup("earlyprintk=", setup_early_printk);
    +
    +#else
    +void early_printk(const char *fmt, ...)
    +{
    +}
    +#endif
    --
    1.5.4.GIT


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