drivers/acpi/processor_idle.c

Source file repositories/reference/linux-study-clean/drivers/acpi/processor_idle.c

File Facts

System
Linux kernel
Corpus path
drivers/acpi/processor_idle.c
Extension
.c
Size
37586 bytes
Lines
1471
Domain
Driver Families
Bucket
drivers/acpi
Inferred role
Driver Families: implementation source
Status
source 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.

Dependency Surface

Detected Declarations

Annotated Snippet

struct acpi_lpi_states_array {
	unsigned int size;
	unsigned int composite_states_size;
	struct acpi_lpi_state *entries;
	struct acpi_lpi_state *composite_states[ACPI_PROCESSOR_MAX_POWER];
};

static int obj_get_integer(union acpi_object *obj, u32 *value)
{
	if (obj->type != ACPI_TYPE_INTEGER)
		return -EINVAL;

	*value = obj->integer.value;
	return 0;
}

static int acpi_processor_evaluate_lpi(acpi_handle handle,
				       struct acpi_lpi_states_array *info)
{
	acpi_status status;
	int ret = 0;
	int pkg_count, state_idx = 1, loop;
	struct acpi_buffer buffer = { ACPI_ALLOCATE_BUFFER, NULL };
	union acpi_object *lpi_data;
	struct acpi_lpi_state *lpi_state;

	status = acpi_evaluate_object(handle, "_LPI", NULL, &buffer);
	if (ACPI_FAILURE(status)) {
		acpi_handle_debug(handle, "No _LPI, giving up\n");
		return -ENODEV;
	}

	lpi_data = buffer.pointer;

	/* There must be at least 4 elements = 3 elements + 1 package */
	if (!lpi_data || lpi_data->type != ACPI_TYPE_PACKAGE ||
	    lpi_data->package.count < 4) {
		pr_debug("not enough elements in _LPI\n");
		ret = -ENODATA;
		goto end;
	}

	pkg_count = lpi_data->package.elements[2].integer.value;

	/* Validate number of power states. */
	if (pkg_count < 1 || pkg_count != lpi_data->package.count - 3) {
		pr_debug("count given by _LPI is not valid\n");
		ret = -ENODATA;
		goto end;
	}

	lpi_state = kzalloc_objs(*lpi_state, pkg_count);
	if (!lpi_state) {
		ret = -ENOMEM;
		goto end;
	}

	info->size = pkg_count;
	info->entries = lpi_state;

	/* LPI States start at index 3 */
	for (loop = 3; state_idx <= pkg_count; loop++, state_idx++, lpi_state++) {
		union acpi_object *element, *pkg_elem, *obj;

		element = &lpi_data->package.elements[loop];
		if (element->type != ACPI_TYPE_PACKAGE || element->package.count < 7)
			continue;

		pkg_elem = element->package.elements;

		obj = pkg_elem + 6;
		if (obj->type == ACPI_TYPE_BUFFER) {
			struct acpi_power_register *reg;

			reg = (struct acpi_power_register *)obj->buffer.pointer;
			if (reg->space_id != ACPI_ADR_SPACE_SYSTEM_IO &&
			    reg->space_id != ACPI_ADR_SPACE_FIXED_HARDWARE)
				continue;

			lpi_state->address = reg->address;
			lpi_state->entry_method =
				reg->space_id == ACPI_ADR_SPACE_FIXED_HARDWARE ?
				ACPI_CSTATE_FFH : ACPI_CSTATE_SYSTEMIO;
		} else if (obj->type == ACPI_TYPE_INTEGER) {
			lpi_state->entry_method = ACPI_CSTATE_INTEGER;
			lpi_state->address = obj->integer.value;
		} else {
			pr_debug("Entry method of state-%d is invalid, disable it.\n",
				 state_idx);
			continue;

Annotation

Implementation Notes