/arch/mips/lib/delay.c

http://github.com/mirrors/linux · C · 69 lines · 39 code · 10 blank · 20 comment · 0 complexity · 06d74bf9021541ecadd407ee710a8111 MD5 · raw file

  1. /*
  2. * This file is subject to the terms and conditions of the GNU General Public
  3. * License. See the file "COPYING" in the main directory of this archive
  4. * for more details.
  5. *
  6. * Copyright (C) 1994 by Waldorf Electronics
  7. * Copyright (C) 1995 - 2000, 01, 03 by Ralf Baechle
  8. * Copyright (C) 1999, 2000 Silicon Graphics, Inc.
  9. * Copyright (C) 2007, 2014 Maciej W. Rozycki
  10. */
  11. #include <linux/delay.h>
  12. #include <linux/export.h>
  13. #include <linux/param.h>
  14. #include <linux/smp.h>
  15. #include <linux/stringify.h>
  16. #include <asm/asm.h>
  17. #include <asm/compiler.h>
  18. #include <asm/war.h>
  19. #ifndef CONFIG_CPU_DADDI_WORKAROUNDS
  20. #define GCC_DADDI_IMM_ASM() "I"
  21. #else
  22. #define GCC_DADDI_IMM_ASM() "r"
  23. #endif
  24. #ifndef CONFIG_HAVE_PLAT_DELAY
  25. void __delay(unsigned long loops)
  26. {
  27. __asm__ __volatile__ (
  28. " .set noreorder \n"
  29. " .align 3 \n"
  30. "1: bnez %0, 1b \n"
  31. " " __stringify(LONG_SUBU) " %0, %1 \n"
  32. " .set reorder \n"
  33. : "=r" (loops)
  34. : GCC_DADDI_IMM_ASM() (1), "0" (loops));
  35. }
  36. EXPORT_SYMBOL(__delay);
  37. /*
  38. * Division by multiplication: you don't have to worry about
  39. * loss of precision.
  40. *
  41. * Use only for very small delays ( < 1 msec). Should probably use a
  42. * lookup table, really, as the multiplications take much too long with
  43. * short delays. This is a "reasonable" implementation, though (and the
  44. * first constant multiplications gets optimized away if the delay is
  45. * a constant)
  46. */
  47. void __udelay(unsigned long us)
  48. {
  49. unsigned int lpj = raw_current_cpu_data.udelay_val;
  50. __delay((us * 0x000010c7ull * HZ * lpj) >> 32);
  51. }
  52. EXPORT_SYMBOL(__udelay);
  53. void __ndelay(unsigned long ns)
  54. {
  55. unsigned int lpj = raw_current_cpu_data.udelay_val;
  56. __delay((ns * 0x00000005ull * HZ * lpj) >> 32);
  57. }
  58. EXPORT_SYMBOL(__ndelay);
  59. #endif