delay-loop.S 1.0 KB

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  1. /* SPDX-License-Identifier: GPL-2.0-only */
  2. /*
  3. * linux/arch/arm/lib/delay.S
  4. *
  5. * Copyright (C) 1995, 1996 Russell King
  6. */
  7. #include <linux/linkage.h>
  8. #include <asm/assembler.h>
  9. #include <asm/delay.h>
  10. .text
  11. .LC0: .word loops_per_jiffy
  12. .LC1: .word UDELAY_MULT
  13. /*
  14. * loops = r0 * HZ * loops_per_jiffy / 1000000
  15. *
  16. * r0 <= 2000
  17. * HZ <= 1000
  18. */
  19. ENTRY(__loop_udelay)
  20. ldr r2, .LC1
  21. mul r0, r2, r0 @ r0 = delay_us * UDELAY_MULT
  22. ENTRY(__loop_const_udelay) @ 0 <= r0 <= 0xfffffaf0
  23. ldr r2, .LC0
  24. ldr r2, [r2]
  25. umull r1, r0, r2, r0 @ r0-r1 = r0 * loops_per_jiffy
  26. adds r1, r1, #0xffffffff @ rounding up ...
  27. adcs r0, r0, r0 @ and right shift by 31
  28. reteq lr
  29. .align 3
  30. @ Delay routine
  31. ENTRY(__loop_delay)
  32. subs r0, r0, #1
  33. #if 0
  34. retls lr
  35. subs r0, r0, #1
  36. retls lr
  37. subs r0, r0, #1
  38. retls lr
  39. subs r0, r0, #1
  40. retls lr
  41. subs r0, r0, #1
  42. retls lr
  43. subs r0, r0, #1
  44. retls lr
  45. subs r0, r0, #1
  46. retls lr
  47. subs r0, r0, #1
  48. #endif
  49. bhi __loop_delay
  50. ret lr
  51. ENDPROC(__loop_udelay)
  52. ENDPROC(__loop_const_udelay)
  53. ENDPROC(__loop_delay)