Linux Kernel  3.7.1
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printf.c
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1 /*
2  * printf.c: Internal prom library printf facility.
3  *
4  * Copyright (C) 1995 David S. Miller ([email protected])
5  * Copyright (C) 1997 Jakub Jelinek ([email protected])
6  * Copyright (c) 2002 Pete Zaitcev ([email protected])
7  *
8  * We used to warn all over the code: DO NOT USE prom_printf(),
9  * and yet people do. Anton's banking code was outputting banks
10  * with prom_printf for most of the 2.4 lifetime. Since an effective
11  * stick is not available, we deployed a carrot: an early printk
12  * through PROM by means of -p boot option. This ought to fix it.
13  * USE printk; if you need, deploy -p.
14  */
15 
16 #include <linux/kernel.h>
17 #include <linux/compiler.h>
18 #include <linux/spinlock.h>
19 
20 #include <asm/openprom.h>
21 #include <asm/oplib.h>
22 
23 #define CONSOLE_WRITE_BUF_SIZE 1024
24 
25 static char ppbuf[1024];
26 static char console_write_buf[CONSOLE_WRITE_BUF_SIZE];
27 static DEFINE_RAW_SPINLOCK(console_write_lock);
28 
29 void notrace prom_write(const char *buf, unsigned int n)
30 {
31  unsigned int dest_len;
32  unsigned long flags;
33  char *dest;
34 
35  dest = console_write_buf;
36  raw_spin_lock_irqsave(&console_write_lock, flags);
37 
38  dest_len = 0;
39  while (n-- != 0) {
40  char ch = *buf++;
41  if (ch == '\n') {
42  *dest++ = '\r';
43  dest_len++;
44  }
45  *dest++ = ch;
46  dest_len++;
47  if (dest_len >= CONSOLE_WRITE_BUF_SIZE - 1) {
48  prom_console_write_buf(console_write_buf, dest_len);
49  dest = console_write_buf;
50  dest_len = 0;
51  }
52  }
53  if (dest_len)
54  prom_console_write_buf(console_write_buf, dest_len);
55 
56  raw_spin_unlock_irqrestore(&console_write_lock, flags);
57 }
58 
59 void notrace prom_printf(const char *fmt, ...)
60 {
61  va_list args;
62  int i;
63 
64  va_start(args, fmt);
65  i = vscnprintf(ppbuf, sizeof(ppbuf), fmt, args);
66  va_end(args);
67 
68  prom_write(ppbuf, i);
69 }