arch/arm/kernel/early_printk.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  *  linux/arch/arm/kernel/early_printk.c
   4  *
   5  *  Copyright (C) 2009 Sascha Hauer <s.hauer@pengutronix.de>
   6  */
   7
   8 #include <linux/kernel.h>
   9 #include <linux/console.h>
  10 #include <linux/init.h>
  11 #include <linux/string.h>
  12
  13 extern void printascii(const char *);
  14
  15 static void early_write(const char *s, unsigned n)
  16 {
  17         char buf[128];
  18         while (n) {
  19                 unsigned l = min(n, sizeof(buf)-1);
  20                 memcpy(buf, s, l);
  21                 buf[l] = 0;
  22                 s += l;
  23                 n -= l;
  24                 printascii(buf);
  25         }
  26 }
  27
  28 static void early_console_write(struct console *con, const char *s, unsigned n)
  29 {
  30         early_write(s, n);
  31 }
  32
  33 static struct console early_console_dev = {
  34         .name =         "earlycon",
  35         .write =        early_console_write,
  36         .flags =        CON_PRINTBUFFER | CON_BOOT,
  37         .index =        -1,
  38 };
  39
  40 static int __init setup_early_printk(char *buf)
  41 {
  42         early_console = &early_console_dev;
  43         register_console(&early_console_dev);
  44         return 0;
  45 }
  46
  47 early_param("earlyprintk", setup_early_printk);