drivers/acpi/processor_pdc.c

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

File Facts

System
Linux kernel
Corpus path
drivers/acpi/processor_pdc.c
Extension
.c
Size
2559 bytes
Lines
121
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

// SPDX-License-Identifier: GPL-2.0
/*
 * Copyright (C) 2005 Intel Corporation
 * Copyright (C) 2009 Hewlett-Packard Development Company, L.P.
 *
 *      Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>
 *      - Added _PDC for platforms with Intel CPUs
 */

#define pr_fmt(fmt) "ACPI: " fmt

#include <linux/slab.h>
#include <linux/acpi.h>
#include <acpi/processor.h>

#include "internal.h"

static void acpi_set_pdc_bits(u32 *buf)
{
	buf[0] = ACPI_PDC_REVISION_ID;
	buf[1] = 1;
	buf[2] = 0;

	/* Twiddle arch-specific bits needed for _PDC */
	arch_acpi_set_proc_cap_bits(&buf[2]);
}

static struct acpi_object_list *acpi_processor_alloc_pdc(void)
{
	struct acpi_object_list *obj_list;
	union acpi_object *obj;
	u32 *buf;

	/* allocate and initialize pdc. It will be used later. */
	obj_list = kmalloc_obj(struct acpi_object_list);
	if (!obj_list)
		goto out;

	obj = kmalloc_obj(union acpi_object);
	if (!obj) {
		kfree(obj_list);
		goto out;
	}

	buf = kmalloc(12, GFP_KERNEL);
	if (!buf) {
		kfree(obj);
		kfree(obj_list);
		goto out;
	}

	acpi_set_pdc_bits(buf);

	obj->type = ACPI_TYPE_BUFFER;
	obj->buffer.length = 12;
	obj->buffer.pointer = (u8 *) buf;
	obj_list->count = 1;
	obj_list->pointer = obj;

	return obj_list;
out:
	pr_err("Memory allocation error\n");
	return NULL;
}

/*
 * _PDC is required for a BIOS-OS handshake for most of the newer
 * ACPI processor features.
 */
static acpi_status
acpi_processor_eval_pdc(acpi_handle handle, struct acpi_object_list *pdc_in)
{
	acpi_status status = AE_OK;

	status = acpi_evaluate_object(handle, "_PDC", pdc_in, NULL);

	if (ACPI_FAILURE(status))
		acpi_handle_debug(handle,
		    "Could not evaluate _PDC, using legacy perf control\n");

	return status;
}

void acpi_processor_set_pdc(acpi_handle handle)
{
	struct acpi_object_list *obj_list;

	if (arch_has_acpi_pdc() == false)
		return;

Annotation

Implementation Notes