1 // SPDX-License-Identifier: GPL-2.0 2 /* 3 * printf.c: Internal prom library printf facility. 4 * 5 * Copyright (C) 1995 David S. Miller (davem@caip.rutgers.edu) 6 * Copyright (C) 1997 Jakub Jelinek (jj@sunsite.mff.cuni.cz) 7 * Copyright (c) 2002 Pete Zaitcev (zaitcev@yahoo.com) 8 * 9 * We used to warn all over the code: DO NOT USE prom_printf(), 10 * and yet people do. Anton's banking code was outputting banks 11 * with prom_printf for most of the 2.4 lifetime. Since an effective 12 * stick is not available, we deployed a carrot: an early printk 13 * through PROM by means of -p boot option. This ought to fix it. 14 * USE printk; if you need, deploy -p. 15 */ 16 17 #include <linux/kernel.h> 18 #include <linux/compiler.h> 19 #include <linux/spinlock.h> 20 21 #include <asm/openprom.h> 22 #include <asm/oplib.h> 23 24 #define CONSOLE_WRITE_BUF_SIZE 1024 25 26 static char ppbuf[1024]; 27 static char console_write_buf[CONSOLE_WRITE_BUF_SIZE]; 28 static DEFINE_RAW_SPINLOCK(console_write_lock); 29 30 void notrace prom_write(const char *buf, unsigned int n) 31 { 32 unsigned int dest_len; 33 unsigned long flags; 34 char *dest; 35 36 dest = console_write_buf; 37 raw_spin_lock_irqsave(&console_write_lock, flags); 38 39 dest_len = 0; 40 while (n-- != 0) { 41 char ch = *buf++; 42 if (ch == '\n') { 43 *dest++ = '\r'; 44 dest_len++; 45 } 46 *dest++ = ch; 47 dest_len++; 48 if (dest_len >= CONSOLE_WRITE_BUF_SIZE - 1) { 49 prom_console_write_buf(console_write_buf, dest_len); 50 dest = console_write_buf; 51 dest_len = 0; 52 } 53 } 54 if (dest_len) 55 prom_console_write_buf(console_write_buf, dest_len); 56 57 raw_spin_unlock_irqrestore(&console_write_lock, flags); 58 } 59 60 void notrace prom_printf(const char *fmt, ...) 61 { 62 va_list args; 63 int i; 64 65 va_start(args, fmt); 66 i = vscnprintf(ppbuf, sizeof(ppbuf), fmt, args); 67 va_end(args); 68 69 prom_write(ppbuf, i); 70 } 71