// SPDX-License-Identifier: GPL-2.0

  /*
   * printf.c:  Internal prom library printf facility.
   *
   * Copyright (C) 1995 David S. Miller (davem@caip.rutgers.edu)
   * Copyright (C) 1997 Jakub Jelinek (jj@sunsite.mff.cuni.cz)
   * Copyright (c) 2002 Pete Zaitcev (zaitcev@yahoo.com)
   *
   * We used to warn all over the code: DO NOT USE prom_printf(),
   * and yet people do. Anton's banking code was outputting banks
   * with prom_printf for most of the 2.4 lifetime. Since an effective
   * stick is not available, we deployed a carrot: an early printk
   * through PROM by means of -p boot option. This ought to fix it.
   * USE printk; if you need, deploy -p.
   */
  
  #include <linux/kernel.h>

  #include <linux/compiler.h>

  #include <linux/spinlock.h>

  
  #include <asm/openprom.h>
  #include <asm/oplib.h>

  #define CONSOLE_WRITE_BUF_SIZE	1024

  static char ppbuf[1024];

  static char console_write_buf[CONSOLE_WRITE_BUF_SIZE];
  static DEFINE_RAW_SPINLOCK(console_write_lock);

  void notrace prom_write(const char *buf, unsigned int n)

  {

  	unsigned int dest_len;
  	unsigned long flags;
  	char *dest;
  
  	dest = console_write_buf;
  	raw_spin_lock_irqsave(&console_write_lock, flags);
  
  	dest_len = 0;

  	while (n-- != 0) {

  		char ch = *buf++;

  		if (ch == '
  ') {

  			*dest++ = '\r';
  			dest_len++;
  		}
  		*dest++ = ch;
  		dest_len++;
  		if (dest_len >= CONSOLE_WRITE_BUF_SIZE - 1) {
  			prom_console_write_buf(console_write_buf, dest_len);
  			dest = console_write_buf;
  			dest_len = 0;

  		}

  	}

  	if (dest_len)
  		prom_console_write_buf(console_write_buf, dest_len);
  
  	raw_spin_unlock_irqrestore(&console_write_lock, flags);

  }

  void notrace prom_printf(const char *fmt, ...)

  {
  	va_list args;
  	int i;
  
  	va_start(args, fmt);
  	i = vscnprintf(ppbuf, sizeof(ppbuf), fmt, args);
  	va_end(args);
  
  	prom_write(ppbuf, i);
  }