arch/sh/kernel/early_printk.c

   1 /*
   2  * arch/sh/kernel/early_printk.c
   3  *
   4  *  Copyright (C) 1999, 2000  Niibe Yutaka
   5  *  Copyright (C) 2002  M. R. Brown
   6  *  Copyright (C) 2004 - 2007  Paul Mundt
   7  *
   8  * This file is subject to the terms and conditions of the GNU General Public
   9  * License.  See the file "COPYING" in the main directory of this archive
  10  * for more details.
  11  */
  12 #include <linux/console.h>
  13 #include <linux/tty.h>
  14 #include <linux/init.h>
  15 #include <linux/io.h>
  16 #include <linux/delay.h>
  17
  18 #include <asm/sh_bios.h>
  19
  20 /*
  21  *      Print a string through the BIOS
  22  */
  23 static void sh_console_write(struct console *co, const char *s,
  24                                  unsigned count)
  25 {
  26         sh_bios_console_write(s, count);
  27 }
  28
  29 /*
  30  *      Setup initial baud/bits/parity. We do two things here:
  31  *      - construct a cflag setting for the first rs_open()
  32  *      - initialize the serial port
  33  *      Return non-zero if we didn't find a serial port.
  34  */
  35 static int __init sh_console_setup(struct console *co, char *options)
  36 {
  37         int     cflag = CREAD | HUPCL | CLOCAL;
  38
  39         /*
  40          *      Now construct a cflag setting.
  41          *      TODO: this is a totally bogus cflag, as we have
  42          *      no idea what serial settings the BIOS is using, or
  43          *      even if its using the serial port at all.
  44          */
  45         cflag |= B115200 | CS8 | /*no parity*/0;
  46
  47         co->cflag = cflag;
  48
  49         return 0;
  50 }
  51
  52 static struct console bios_console = {
  53         .name           = "bios",
  54         .write          = sh_console_write,
  55         .setup          = sh_console_setup,
  56         .flags          = CON_PRINTBUFFER,
  57         .index          = -1,
  58 };
  59
  60 static struct console *early_console;
  61
  62 static int __init setup_early_printk(char *buf)
  63 {
  64         int keep_early = 0;
  65
  66         if (!buf)
  67                 return 0;
  68
  69         if (strstr(buf, "keep"))
  70                 keep_early = 1;
  71
  72         if (!strncmp(buf, "bios", 4))
  73                 early_console = &bios_console;
  74
  75         if (likely(early_console)) {
  76                 if (keep_early)
  77                         early_console->flags &= ~CON_BOOT;
  78                 else
  79                         early_console->flags |= CON_BOOT;
  80                 register_console(early_console);
  81         }
  82
  83         return 0;
  84 }
  85 early_param("earlyprintk", setup_early_printk);