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/xen.h>
23#include <xen/interface/version.h>
24#include <xen/xen-ops.h>
25#include <asm/xen/hypercall.h>
26
27#define ACPI_PROCESSOR_AGGREGATOR_CLASS "acpi_pad"
28#define ACPI_PROCESSOR_AGGREGATOR_DEVICE_NAME "Processor Aggregator"
29#define ACPI_PROCESSOR_AGGREGATOR_NOTIFY 0x80
30static DEFINE_MUTEX(xen_cpu_lock);
31
32static int xen_acpi_pad_idle_cpus(unsigned int idle_nums)
33{
34 struct xen_platform_op op;
35
36 op.cmd = XENPF_core_parking;
37 op.u.core_parking.type = XEN_CORE_PARKING_SET;
38 op.u.core_parking.idle_nums = idle_nums;
39
40 return HYPERVISOR_platform_op(&op);
41}
42
43static int xen_acpi_pad_idle_cpus_num(void)
44{
45 struct xen_platform_op op;
46
47 op.cmd = XENPF_core_parking;
48 op.u.core_parking.type = XEN_CORE_PARKING_GET;
49
50 return HYPERVISOR_platform_op(&op)
51 ?: op.u.core_parking.idle_nums;
52}
53
54/*
55 * Query firmware how many CPUs should be idle
56 * return -1 on failure
57 */
58static int acpi_pad_pur(acpi_handle handle)
59{
60 struct acpi_buffer buffer = {ACPI_ALLOCATE_BUFFER, NULL};
61 union acpi_object *package;
62 int num = -1;
63
64 if (ACPI_FAILURE(acpi_evaluate_object(handle, "_PUR", NULL, &buffer)))
65 return num;
66
67 if (!buffer.length || !buffer.pointer)
68 return num;
69
70 package = buffer.pointer;
71
72 if (package->type == ACPI_TYPE_PACKAGE &&
73 package->package.count == 2 &&
74 package->package.elements[0].integer.value == 1) /* rev 1 */
75 num = package->package.elements[1].integer.value;
76
77 kfree(buffer.pointer);
78 return num;
79}
80
81static void acpi_pad_handle_notify(acpi_handle handle)
82{
83 int idle_nums;
84 struct acpi_buffer param = {
85 .length = 4,
86 .pointer = (void *)&idle_nums,
87 };
88
89
90 mutex_lock(&xen_cpu_lock);
91 idle_nums = acpi_pad_pur(handle);
92 if (idle_nums < 0) {
93 mutex_unlock(&xen_cpu_lock);
94 return;
95 }
96
97 idle_nums = xen_acpi_pad_idle_cpus(idle_nums)
98 ?: xen_acpi_pad_idle_cpus_num();
99 if (idle_nums >= 0)
100 acpi_evaluate_ost(handle, ACPI_PROCESSOR_AGGREGATOR_NOTIFY,
101 0, &param);
102 mutex_unlock(&xen_cpu_lock);
103}
104
105static void acpi_pad_notify(acpi_handle handle, u32 event,
106 void *data)
107{
108 switch (event) {
109 case ACPI_PROCESSOR_AGGREGATOR_NOTIFY:
110 acpi_pad_handle_notify(handle);
111 break;
112 default:
113 pr_warn("Unsupported event [0x%x]\n", event);
114 break;
115 }
116}
117
118static int acpi_pad_add(struct acpi_device *device)
119{
120 acpi_status status;
121
122 strcpy(acpi_device_name(device), ACPI_PROCESSOR_AGGREGATOR_DEVICE_NAME);
123 strcpy(acpi_device_class(device), ACPI_PROCESSOR_AGGREGATOR_CLASS);
124
125 status = acpi_install_notify_handler(device->handle,
126 ACPI_DEVICE_NOTIFY, acpi_pad_notify, device);
127 if (ACPI_FAILURE(status))
128 return -ENODEV;
129
130 return 0;
131}
132
133static int acpi_pad_remove(struct acpi_device *device)
134{
135 mutex_lock(&xen_cpu_lock);
136 xen_acpi_pad_idle_cpus(0);
137 mutex_unlock(&xen_cpu_lock);
138
139 acpi_remove_notify_handler(device->handle,
140 ACPI_DEVICE_NOTIFY, acpi_pad_notify);
141 return 0;
142}
143
144static const struct acpi_device_id pad_device_ids[] = {
145 {"ACPI000C", 0},
146 {"", 0},
147};
148
149static struct acpi_driver acpi_pad_driver = {
150 .name = "processor_aggregator",
151 .class = ACPI_PROCESSOR_AGGREGATOR_CLASS,
152 .ids = pad_device_ids,
153 .ops = {
154 .add = acpi_pad_add,
155 .remove = acpi_pad_remove,
156 },
157};
158
159static int __init xen_acpi_pad_init(void)
160{
161 /* Only DOM0 is responsible for Xen acpi pad */
162 if (!xen_initial_domain())
163 return -ENODEV;
164
165 /* Only Xen4.2 or later support Xen acpi pad */
166 if (!xen_running_on_version_or_later(4, 2))
167 return -ENODEV;
168
169 return acpi_bus_register_driver(&acpi_pad_driver);
170}
171subsys_initcall(xen_acpi_pad_init);
172