arch/sparc/prom/printf.c

   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 }