arch/h8300/kernel/sim-console.c

   1 /*
   2  * arch/h8300/kernel/early_printk.c
   3  *
   4  *  Copyright (C) 2009 Yoshinori Sato <ysato@users.sourceforge.jp>
   5  *
   6  * This file is subject to the terms and conditions of the GNU General Public
   7  * License.  See the file "COPYING" in the main directory of this archive
   8  * for more details.
   9  */
  10 #include <linux/console.h>
  11 #include <linux/tty.h>
  12 #include <linux/init.h>
  13 #include <linux/io.h>
  14 #include <linux/platform_device.h>
  15
  16 static void sim_write(struct console *co, const char *ptr,
  17                                  unsigned len)
  18 {
  19         register const int fd __asm__("er0") = 1; /* stdout */
  20         register const char *_ptr __asm__("er1") = ptr;
  21         register const unsigned _len __asm__("er2") = len;
  22
  23         __asm__(".byte 0x5e,0x00,0x00,0xc7\n\t" /* jsr @0xc7 (sys_write) */
  24                 : : "g"(fd), "g"(_ptr), "g"(_len));
  25 }
  26
  27 static struct console sim_console = {
  28         .name           = "sim_console",
  29         .write          = sim_write,
  30         .setup          = NULL,
  31         .flags          = CON_PRINTBUFFER,
  32         .index          = -1,
  33 };
  34
  35 static char sim_console_buf[32];
  36
  37 static int sim_probe(struct platform_device *pdev)
  38 {
  39         if (sim_console.data)
  40                 return -EEXIST;
  41
  42         if (!strstr(sim_console_buf, "keep"))
  43                 sim_console.flags |= CON_BOOT;
  44
  45         register_console(&sim_console);
  46         return 0;
  47 }
  48
  49 static int sim_remove(struct platform_device *pdev)
  50 {
  51         return 0;
  52 }
  53
  54 static struct platform_driver sim_driver = {
  55         .probe          = sim_probe,
  56         .remove         = sim_remove,
  57         .driver         = {
  58                 .name   = "h8300-sim",
  59                 .owner  = THIS_MODULE,
  60         },
  61 };
  62
  63 early_platform_init_buffer("earlyprintk", &sim_driver,
  64                            sim_console_buf, ARRAY_SIZE(sim_console_buf));
  65
  66 static struct platform_device sim_console_device = {
  67         .name           = "h8300-sim",
  68         .id             = 0,
  69 };
  70
  71 static struct platform_device *devices[] __initdata = {
  72         &sim_console_device,
  73 };
  74
  75 void __init sim_console_register(void)
  76 {
  77         early_platform_add_devices(devices,
  78                                    ARRAY_SIZE(devices));
  79 }