hwtimer.c 4.8 KB

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  1. // SPDX-License-Identifier: BSD-3-Clause OR GPL-2.0
  2. /******************************************************************************
  3. *
  4. * Name: hwtimer.c - ACPI Power Management Timer Interface
  5. *
  6. * Copyright (C) 2000 - 2022, Intel Corp.
  7. *
  8. *****************************************************************************/
  9. #define EXPORT_ACPI_INTERFACES
  10. #include <acpi/acpi.h>
  11. #include "accommon.h"
  12. #define _COMPONENT ACPI_HARDWARE
  13. ACPI_MODULE_NAME("hwtimer")
  14. #if (!ACPI_REDUCED_HARDWARE) /* Entire module */
  15. /******************************************************************************
  16. *
  17. * FUNCTION: acpi_get_timer_resolution
  18. *
  19. * PARAMETERS: resolution - Where the resolution is returned
  20. *
  21. * RETURN: Status and timer resolution
  22. *
  23. * DESCRIPTION: Obtains resolution of the ACPI PM Timer (24 or 32 bits).
  24. *
  25. ******************************************************************************/
  26. acpi_status acpi_get_timer_resolution(u32 * resolution)
  27. {
  28. ACPI_FUNCTION_TRACE(acpi_get_timer_resolution);
  29. if (!resolution) {
  30. return_ACPI_STATUS(AE_BAD_PARAMETER);
  31. }
  32. if ((acpi_gbl_FADT.flags & ACPI_FADT_32BIT_TIMER) == 0) {
  33. *resolution = 24;
  34. } else {
  35. *resolution = 32;
  36. }
  37. return_ACPI_STATUS(AE_OK);
  38. }
  39. ACPI_EXPORT_SYMBOL(acpi_get_timer_resolution)
  40. /******************************************************************************
  41. *
  42. * FUNCTION: acpi_get_timer
  43. *
  44. * PARAMETERS: ticks - Where the timer value is returned
  45. *
  46. * RETURN: Status and current timer value (ticks)
  47. *
  48. * DESCRIPTION: Obtains current value of ACPI PM Timer (in ticks).
  49. *
  50. ******************************************************************************/
  51. acpi_status acpi_get_timer(u32 * ticks)
  52. {
  53. acpi_status status;
  54. u64 timer_value;
  55. ACPI_FUNCTION_TRACE(acpi_get_timer);
  56. if (!ticks) {
  57. return_ACPI_STATUS(AE_BAD_PARAMETER);
  58. }
  59. /* ACPI 5.0A: PM Timer is optional */
  60. if (!acpi_gbl_FADT.xpm_timer_block.address) {
  61. return_ACPI_STATUS(AE_SUPPORT);
  62. }
  63. status = acpi_hw_read(&timer_value, &acpi_gbl_FADT.xpm_timer_block);
  64. if (ACPI_SUCCESS(status)) {
  65. /* ACPI PM Timer is defined to be 32 bits (PM_TMR_LEN) */
  66. *ticks = (u32)timer_value;
  67. }
  68. return_ACPI_STATUS(status);
  69. }
  70. ACPI_EXPORT_SYMBOL(acpi_get_timer)
  71. /******************************************************************************
  72. *
  73. * FUNCTION: acpi_get_timer_duration
  74. *
  75. * PARAMETERS: start_ticks - Starting timestamp
  76. * end_ticks - End timestamp
  77. * time_elapsed - Where the elapsed time is returned
  78. *
  79. * RETURN: Status and time_elapsed
  80. *
  81. * DESCRIPTION: Computes the time elapsed (in microseconds) between two
  82. * PM Timer time stamps, taking into account the possibility of
  83. * rollovers, the timer resolution, and timer frequency.
  84. *
  85. * The PM Timer's clock ticks at roughly 3.6 times per
  86. * _microsecond_, and its clock continues through Cx state
  87. * transitions (unlike many CPU timestamp counters) -- making it
  88. * a versatile and accurate timer.
  89. *
  90. * Note that this function accommodates only a single timer
  91. * rollover. Thus for 24-bit timers, this function should only
  92. * be used for calculating durations less than ~4.6 seconds
  93. * (~20 minutes for 32-bit timers) -- calculations below:
  94. *
  95. * 2**24 Ticks / 3,600,000 Ticks/Sec = 4.66 sec
  96. * 2**32 Ticks / 3,600,000 Ticks/Sec = 1193 sec or 19.88 minutes
  97. *
  98. ******************************************************************************/
  99. acpi_status
  100. acpi_get_timer_duration(u32 start_ticks, u32 end_ticks, u32 *time_elapsed)
  101. {
  102. acpi_status status;
  103. u64 delta_ticks;
  104. u64 quotient;
  105. ACPI_FUNCTION_TRACE(acpi_get_timer_duration);
  106. if (!time_elapsed) {
  107. return_ACPI_STATUS(AE_BAD_PARAMETER);
  108. }
  109. /* ACPI 5.0A: PM Timer is optional */
  110. if (!acpi_gbl_FADT.xpm_timer_block.address) {
  111. return_ACPI_STATUS(AE_SUPPORT);
  112. }
  113. if (start_ticks == end_ticks) {
  114. *time_elapsed = 0;
  115. return_ACPI_STATUS(AE_OK);
  116. }
  117. /*
  118. * Compute Tick Delta:
  119. * Handle (max one) timer rollovers on 24-bit versus 32-bit timers.
  120. */
  121. delta_ticks = end_ticks;
  122. if (start_ticks > end_ticks) {
  123. if ((acpi_gbl_FADT.flags & ACPI_FADT_32BIT_TIMER) == 0) {
  124. /* 24-bit Timer */
  125. delta_ticks |= (u64)1 << 24;
  126. } else {
  127. /* 32-bit Timer */
  128. delta_ticks |= (u64)1 << 32;
  129. }
  130. }
  131. delta_ticks -= start_ticks;
  132. /*
  133. * Compute Duration (Requires a 64-bit multiply and divide):
  134. *
  135. * time_elapsed (microseconds) =
  136. * (delta_ticks * ACPI_USEC_PER_SEC) / ACPI_PM_TIMER_FREQUENCY;
  137. */
  138. status = acpi_ut_short_divide(delta_ticks * ACPI_USEC_PER_SEC,
  139. ACPI_PM_TIMER_FREQUENCY, &quotient, NULL);
  140. *time_elapsed = (u32)quotient;
  141. return_ACPI_STATUS(status);
  142. }
  143. ACPI_EXPORT_SYMBOL(acpi_get_timer_duration)
  144. #endif /* !ACPI_REDUCED_HARDWARE */