1// SPDX-License-Identifier: GPL-2.0
2/*
3 * Copyright (C) 2005 Intel Corporation
4 * Copyright (C) 2009 Hewlett-Packard Development Company, L.P.
5 *
6 *      Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>
7 *      - Added _PDC for platforms with Intel CPUs
8 */
9
10#define pr_fmt(fmt) "ACPI: " fmt
11
12#include <linux/slab.h>
13#include <linux/acpi.h>
14#include <acpi/processor.h>
15
16#include "internal.h"
17
18static void acpi_set_pdc_bits(u32 *buf)
19{
20	buf[0] = ACPI_PDC_REVISION_ID;
21	buf[1] = 1;
22	buf[2] = 0;
23
24	/* Twiddle arch-specific bits needed for _PDC */
25	arch_acpi_set_proc_cap_bits(&buf[2]);
26}
27
28static struct acpi_object_list *acpi_processor_alloc_pdc(void)
29{
30	struct acpi_object_list *obj_list;
31	union acpi_object *obj;
32	u32 *buf;
33
34	/* allocate and initialize pdc. It will be used later. */
35	obj_list = kmalloc(sizeof(struct acpi_object_list), GFP_KERNEL);
36	if (!obj_list)
37		goto out;
38
39	obj = kmalloc(sizeof(union acpi_object), GFP_KERNEL);
40	if (!obj) {
41		kfree(obj_list);
42		goto out;
43	}
44
45	buf = kmalloc(12, GFP_KERNEL);
46	if (!buf) {
47		kfree(obj);
48		kfree(obj_list);
49		goto out;
50	}
51
52	acpi_set_pdc_bits(buf);
53
54	obj->type = ACPI_TYPE_BUFFER;
55	obj->buffer.length = 12;
56	obj->buffer.pointer = (u8 *) buf;
57	obj_list->count = 1;
58	obj_list->pointer = obj;
59
60	return obj_list;
61out:
62	pr_err("Memory allocation error\n");
63	return NULL;
64}
65
66/*
67 * _PDC is required for a BIOS-OS handshake for most of the newer
68 * ACPI processor features.
69 */
70static acpi_status
71acpi_processor_eval_pdc(acpi_handle handle, struct acpi_object_list *pdc_in)
72{
73	acpi_status status = AE_OK;
74
75	status = acpi_evaluate_object(handle, "_PDC", pdc_in, NULL);
76
77	if (ACPI_FAILURE(status))
78		acpi_handle_debug(handle,
79		    "Could not evaluate _PDC, using legacy perf control\n");
80
81	return status;
82}
83
84void acpi_processor_set_pdc(acpi_handle handle)
85{
86	struct acpi_object_list *obj_list;
87
88	if (arch_has_acpi_pdc() == false)
89		return;
90
91	obj_list = acpi_processor_alloc_pdc();
92	if (!obj_list)
93		return;
94
95	acpi_processor_eval_pdc(handle, obj_list);
96
97	kfree(obj_list->pointer->buffer.pointer);
98	kfree(obj_list->pointer);
99	kfree(obj_list);
100}
101
102static acpi_status __init
103early_init_pdc(acpi_handle handle, u32 lvl, void *context, void **rv)
104{
105	if (processor_physically_present(handle) == false)
106		return AE_OK;
107
108	acpi_processor_set_pdc(handle);
109	return AE_OK;
110}
111
112void __init acpi_early_processor_set_pdc(void)
113{
114	acpi_proc_quirk_mwait_check();
115
116	acpi_walk_namespace(ACPI_TYPE_PROCESSOR, ACPI_ROOT_OBJECT,
117			    ACPI_UINT32_MAX,
118			    early_init_pdc, NULL, NULL, NULL);
119	acpi_get_devices(ACPI_PROCESSOR_DEVICE_HID, early_init_pdc, NULL, NULL);
120}
121