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delay.S

delay.S 1.3 KB
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  1. /*
    2. 

  2.  *  linux/arch/arm/lib/delay.S
    3. 

  3.  *
    4. 

  4.  *  Copyright (C) 1995, 1996 Russell King
    5. 

  5.  *
    6. 

  6.  * This program is free software; you can redistribute it and/or modify
    7. 

  7.  * it under the terms of the GNU General Public License version 2 as
    8. 

  8.  * published by the Free Software Foundation.
    9. 

  9.  */
    10. 

  10. #include <linux/linkage.h>
    11. 

  11. #include <asm/assembler.h>
    12. 

  12. #include <asm/param.h>
    13. 

  13. 		.text
    14. 

  14. 

  15. .LC0:		.word	loops_per_jiffy
    16. 

  16. .LC1:		.word	(2199023*HZ)>>11
    17. 

  17. 

  18. /*
    19. 

  19.  * r0  <= 2000
    20. 

  20.  * lpj <= 0x01ffffff (max. 3355 bogomips)
    21. 

  21.  * HZ  <= 1000
    22. 

  22.  */
    23. 

  23. 

  24. ENTRY(__udelay)
    25. 

  25. 		ldr	r2, .LC1
    26. 

  26. 		mul	r0, r2, r0
    27. 

  27. ENTRY(__const_udelay)				@ 0 <= r0 <= 0x7fffff06
    28. 

  28. 		mov	r1, #-1
    29. 

  29. 		ldr	r2, .LC0
    30. 

  30. 		ldr	r2, [r2]		@ max = 0x01ffffff
    31. 

  31. 		add	r0, r0, r1, lsr #32-14
    32. 

  32. 		mov	r0, r0, lsr #14		@ max = 0x0001ffff
    33. 

  33. 		add	r2, r2, r1, lsr #32-10
    34. 

  34. 		mov	r2, r2, lsr #10		@ max = 0x00007fff
    35. 

  35. 		mul	r0, r2, r0		@ max = 2^32-1
    36. 

  36. 		add	r0, r0, r1, lsr #32-6
    37. 

  37. 		movs	r0, r0, lsr #6
    38. 

  38. 		moveq	pc, lr
    39. 

  39. 

  40. /*
    41. 

  41.  * loops = r0 * HZ * loops_per_jiffy / 1000000
    42. 

  42.  *
    43. 

  43.  * Oh, if only we had a cycle counter...
    44. 

  44.  */
    45. 

  45. 

  46. @ Delay routine
    47. 

  47. ENTRY(__delay)
    48. 

  48. 		subs	r0, r0, #1
    49. 

  49. #if 0
    50. 

  50. 		movls	pc, lr
    51. 

  51. 		subs	r0, r0, #1
    52. 

  52. 		movls	pc, lr
    53. 

  53. 		subs	r0, r0, #1
    54. 

  54. 		movls	pc, lr
    55. 

  55. 		subs	r0, r0, #1
    56. 

  56. 		movls	pc, lr
    57. 

  57. 		subs	r0, r0, #1
    58. 

  58. 		movls	pc, lr
    59. 

  59. 		subs	r0, r0, #1
    60. 

  60. 		movls	pc, lr
    61. 

  61. 		subs	r0, r0, #1
    62. 

  62. 		movls	pc, lr
    63. 

  63. 		subs	r0, r0, #1
    64. 

  64. #endif
    65. 

  65. 		bhi	__delay
    66. 

  66. 		mov	pc, lr
    67. 

  67. ENDPROC(__udelay)
    68. 

  68. ENDPROC(__const_udelay)
    69. 

  69. ENDPROC(__delay)
    70. 

  70.