drivers/acpi/acpica/hwtimer.c

File Facts

System

Linux kernel

Corpus path

drivers/acpi/acpica/hwtimer.c

Extension

.c

Size

4911 bytes

Lines

176

Domain

Driver Families

Bucket

drivers/acpi

Inferred role

Driver Families: exported/initcall integration point

Status

integration implementation candidate

Why This File Exists

Repeatable hardware-adapter layer. Deep compatibility for every driver is out of scope; this atlas records patterns, probe lifecycles, bus glue, IRQ/DMA usage, and links back to core abstractions.

• Repeatable hardware-adapter layer. Deep compatibility for every driver is out of scope; this atlas records patterns, probe lifecycles, bus glue, IRQ/DMA usage, and links back to core abstractions.
• Exports symbols or registers init work; inspect boot/module ordering and who consumes the exported contract.

Dependency Surface

• acpi/acpi.h
• accommon.h

Detected Declarations

• function Copyright
• function acpi_get_timer
• function transitions

Annotated Snippet

if ((acpi_gbl_FADT.flags & ACPI_FADT_32BIT_TIMER) == 0) {

			/* 24-bit Timer */

			delta_ticks |= (u64)1 << 24;
		} else {
			/* 32-bit Timer */

			delta_ticks |= (u64)1 << 32;
		}
	}
	delta_ticks -= start_ticks;

	/*
	 * Compute Duration (Requires a 64-bit multiply and divide):
	 *
	 * time_elapsed (microseconds) =
	 *  (delta_ticks * ACPI_USEC_PER_SEC) / ACPI_PM_TIMER_FREQUENCY;
	 */
	status = acpi_ut_short_divide(delta_ticks * ACPI_USEC_PER_SEC,
				      ACPI_PM_TIMER_FREQUENCY, &quotient, NULL);

	*time_elapsed = (u32)quotient;
	return_ACPI_STATUS(status);
}

ACPI_EXPORT_SYMBOL(acpi_get_timer_duration)
#endif				/* !ACPI_REDUCED_HARDWARE */

Annotation

• Immediate include surface: `acpi/acpi.h`, `accommon.h`.
• Detected declarations: `function Copyright`, `function acpi_get_timer`, `function transitions`.
• Atlas domain: Driver Families / drivers/acpi.
• Implementation status: integration implementation candidate.

Implementation Notes

• This generated page is the file-by-file coverage layer; curated subsystem chapters should link here when they synthesize a multi-file control flow.
• Core OS pages should be promoted from atlas-only to deep-reviewed when they explain data structures, invariants, locking, lifecycle, and C implementation snippets.
• Driver-family pages are intentionally pattern-oriented unless they are part of the selected PCIe/NVMe representative device path.