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); 48