[go: nahoru, domu]
1/*
2 * xen-acpi-pad.c - Xen pad interface
3 *
4 * Copyright (c) 2012, Intel Corporation.
5 *    Author: Liu, Jinsong <jinsong.liu@intel.com>
6 *
7 * This program is free software; you can redistribute it and/or modify it
8 * under the terms and conditions of the GNU General Public License,
9 * version 2, as published by the Free Software Foundation.
10 *
11 * This program is distributed in the hope it will be useful, but WITHOUT
12 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
13 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
14 * more details.
15 */
16
17#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
18
19#include <linux/kernel.h>
20#include <linux/types.h>
21#include <linux/acpi.h>
22#include <xen/interface/version.h>
23#include <xen/xen-ops.h>
24#include <asm/xen/hypercall.h>
25
26#define ACPI_PROCESSOR_AGGREGATOR_CLASS	"acpi_pad"
27#define ACPI_PROCESSOR_AGGREGATOR_DEVICE_NAME "Processor Aggregator"
28#define ACPI_PROCESSOR_AGGREGATOR_NOTIFY 0x80
29static DEFINE_MUTEX(xen_cpu_lock);
30
31static int xen_acpi_pad_idle_cpus(unsigned int idle_nums)
32{
33	struct xen_platform_op op;
34
35	op.cmd = XENPF_core_parking;
36	op.u.core_parking.type = XEN_CORE_PARKING_SET;
37	op.u.core_parking.idle_nums = idle_nums;
38
39	return HYPERVISOR_dom0_op(&op);
40}
41
42static int xen_acpi_pad_idle_cpus_num(void)
43{
44	struct xen_platform_op op;
45
46	op.cmd = XENPF_core_parking;
47	op.u.core_parking.type = XEN_CORE_PARKING_GET;
48
49	return HYPERVISOR_dom0_op(&op)
50	       ?: op.u.core_parking.idle_nums;
51}
52
53/*
54 * Query firmware how many CPUs should be idle
55 * return -1 on failure
56 */
57static int acpi_pad_pur(acpi_handle handle)
58{
59	struct acpi_buffer buffer = {ACPI_ALLOCATE_BUFFER, NULL};
60	union acpi_object *package;
61	int num = -1;
62
63	if (ACPI_FAILURE(acpi_evaluate_object(handle, "_PUR", NULL, &buffer)))
64		return num;
65
66	if (!buffer.length || !buffer.pointer)
67		return num;
68
69	package = buffer.pointer;
70
71	if (package->type == ACPI_TYPE_PACKAGE &&
72		package->package.count == 2 &&
73		package->package.elements[0].integer.value == 1) /* rev 1 */
74		num = package->package.elements[1].integer.value;
75
76	kfree(buffer.pointer);
77	return num;
78}
79
80static void acpi_pad_handle_notify(acpi_handle handle)
81{
82	int idle_nums;
83	struct acpi_buffer param = {
84		.length = 4,
85		.pointer = (void *)&idle_nums,
86	};
87
88
89	mutex_lock(&xen_cpu_lock);
90	idle_nums = acpi_pad_pur(handle);
91	if (idle_nums < 0) {
92		mutex_unlock(&xen_cpu_lock);
93		return;
94	}
95
96	idle_nums = xen_acpi_pad_idle_cpus(idle_nums)
97		    ?: xen_acpi_pad_idle_cpus_num();
98	if (idle_nums >= 0)
99		acpi_evaluate_ost(handle, ACPI_PROCESSOR_AGGREGATOR_NOTIFY,
100				  0, &param);
101	mutex_unlock(&xen_cpu_lock);
102}
103
104static void acpi_pad_notify(acpi_handle handle, u32 event,
105	void *data)
106{
107	switch (event) {
108	case ACPI_PROCESSOR_AGGREGATOR_NOTIFY:
109		acpi_pad_handle_notify(handle);
110		break;
111	default:
112		pr_warn("Unsupported event [0x%x]\n", event);
113		break;
114	}
115}
116
117static int acpi_pad_add(struct acpi_device *device)
118{
119	acpi_status status;
120
121	strcpy(acpi_device_name(device), ACPI_PROCESSOR_AGGREGATOR_DEVICE_NAME);
122	strcpy(acpi_device_class(device), ACPI_PROCESSOR_AGGREGATOR_CLASS);
123
124	status = acpi_install_notify_handler(device->handle,
125		ACPI_DEVICE_NOTIFY, acpi_pad_notify, device);
126	if (ACPI_FAILURE(status))
127		return -ENODEV;
128
129	return 0;
130}
131
132static int acpi_pad_remove(struct acpi_device *device)
133{
134	mutex_lock(&xen_cpu_lock);
135	xen_acpi_pad_idle_cpus(0);
136	mutex_unlock(&xen_cpu_lock);
137
138	acpi_remove_notify_handler(device->handle,
139		ACPI_DEVICE_NOTIFY, acpi_pad_notify);
140	return 0;
141}
142
143static const struct acpi_device_id pad_device_ids[] = {
144	{"ACPI000C", 0},
145	{"", 0},
146};
147
148static struct acpi_driver acpi_pad_driver = {
149	.name = "processor_aggregator",
150	.class = ACPI_PROCESSOR_AGGREGATOR_CLASS,
151	.ids = pad_device_ids,
152	.ops = {
153		.add = acpi_pad_add,
154		.remove = acpi_pad_remove,
155	},
156};
157
158static int __init xen_acpi_pad_init(void)
159{
160	/* Only DOM0 is responsible for Xen acpi pad */
161	if (!xen_initial_domain())
162		return -ENODEV;
163
164	/* Only Xen4.2 or later support Xen acpi pad */
165	if (!xen_running_on_version_or_later(4, 2))
166		return -ENODEV;
167
168	return acpi_bus_register_driver(&acpi_pad_driver);
169}
170subsys_initcall(xen_acpi_pad_init);
171