printf.c 1.7 KB

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  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. #include <linux/kernel.h>
  17. #include <linux/compiler.h>
  18. #include <linux/spinlock.h>
  19. #include <asm/openprom.h>
  20. #include <asm/oplib.h>
  21. #define CONSOLE_WRITE_BUF_SIZE 1024
  22. static char ppbuf[1024];
  23. static char console_write_buf[CONSOLE_WRITE_BUF_SIZE];
  24. static DEFINE_RAW_SPINLOCK(console_write_lock);
  25. void notrace prom_write(const char *buf, unsigned int n)
  26. {
  27. unsigned int dest_len;
  28. unsigned long flags;
  29. char *dest;
  30. dest = console_write_buf;
  31. raw_spin_lock_irqsave(&console_write_lock, flags);
  32. dest_len = 0;
  33. while (n-- != 0) {
  34. char ch = *buf++;
  35. if (ch == '\n') {
  36. *dest++ = '\r';
  37. dest_len++;
  38. }
  39. *dest++ = ch;
  40. dest_len++;
  41. if (dest_len >= CONSOLE_WRITE_BUF_SIZE - 1) {
  42. prom_console_write_buf(console_write_buf, dest_len);
  43. dest = console_write_buf;
  44. dest_len = 0;
  45. }
  46. }
  47. if (dest_len)
  48. prom_console_write_buf(console_write_buf, dest_len);
  49. raw_spin_unlock_irqrestore(&console_write_lock, flags);
  50. }
  51. void notrace prom_printf(const char *fmt, ...)
  52. {
  53. va_list args;
  54. int i;
  55. va_start(args, fmt);
  56. i = vscnprintf(ppbuf, sizeof(ppbuf), fmt, args);
  57. va_end(args);
  58. prom_write(ppbuf, i);
  59. }