arch/h8300/kernel/sim-console.c

   1 /*
   2  * arch/h8300/kernel/sim-console.c
   3  *
   4  *  Copyright (C) 2015 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/init.h>
  12 #include <linux/serial_core.h>
  13
  14 static void sim_write(struct console *con, const char *s, unsigned n)
  15 {
  16         register const char *_ptr __asm__("er1") = s;
  17         register const unsigned _len __asm__("er2") = n;
  18
  19         __asm__("sub.l er0,er0\n\t"             /* er0 = 1 (stdout) */
  20                 "inc.l #1,er0\n\t"
  21                 ".byte 0x5e,0x00,0x00,0xc7\n\t" /* jsr @0xc7 (sys_write) */
  22                 : : "g"(_ptr), "g"(_len):"er0");
  23 }
  24
  25 static int __init sim_setup(struct earlycon_device *device, const char *opt)
  26 {
  27         device->con->write = sim_write;
  28         return 0;
  29 }
  30
  31 EARLYCON_DECLARE(h8sim, sim_setup);