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
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