1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * xen-acpi-pad.c - Xen pad interface
4 *
5 * Copyright (c) 2012, Intel Corporation.
6 * Author: Liu, Jinsong <jinsong.liu@intel.com>
7 */
8
9#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
10
11#include <linux/kernel.h>
12#include <linux/types.h>
13#include <linux/acpi.h>
14#include <xen/xen.h>
15#include <xen/interface/version.h>
16#include <xen/xen-ops.h>
17#include <asm/xen/hypercall.h>
18
19#define ACPI_PROCESSOR_AGGREGATOR_CLASS "acpi_pad"
20#define ACPI_PROCESSOR_AGGREGATOR_DEVICE_NAME "Processor Aggregator"
21#define ACPI_PROCESSOR_AGGREGATOR_NOTIFY 0x80
22static DEFINE_MUTEX(xen_cpu_lock);
23
24static int xen_acpi_pad_idle_cpus(unsigned int idle_nums)
25{
26 struct xen_platform_op op;
27
28 op.cmd = XENPF_core_parking;
29 op.u.core_parking.type = XEN_CORE_PARKING_SET;
30 op.u.core_parking.idle_nums = idle_nums;
31
32 return HYPERVISOR_platform_op(op: &op);
33}
34
35static int xen_acpi_pad_idle_cpus_num(void)
36{
37 struct xen_platform_op op;
38
39 op.cmd = XENPF_core_parking;
40 op.u.core_parking.type = XEN_CORE_PARKING_GET;
41
42 return HYPERVISOR_platform_op(op: &op)
43 ?: op.u.core_parking.idle_nums;
44}
45
46/*
47 * Query firmware how many CPUs should be idle
48 * return -1 on failure
49 */
50static int acpi_pad_pur(acpi_handle handle)
51{
52 struct acpi_buffer buffer = {ACPI_ALLOCATE_BUFFER, NULL};
53 union acpi_object *package;
54 int num = -1;
55
56 if (ACPI_FAILURE(acpi_evaluate_object(handle, "_PUR", NULL, &buffer)))
57 return num;
58
59 if (!buffer.length || !buffer.pointer)
60 return num;
61
62 package = buffer.pointer;
63
64 if (package->type == ACPI_TYPE_PACKAGE &&
65 package->package.count == 2 &&
66 package->package.elements[0].integer.value == 1) /* rev 1 */
67 num = package->package.elements[1].integer.value;
68
69 kfree(objp: buffer.pointer);
70 return num;
71}
72
73static void acpi_pad_handle_notify(acpi_handle handle)
74{
75 int idle_nums;
76 struct acpi_buffer param = {
77 .length = 4,
78 .pointer = (void *)&idle_nums,
79 };
80
81
82 mutex_lock(&xen_cpu_lock);
83 idle_nums = acpi_pad_pur(handle);
84 if (idle_nums < 0) {
85 mutex_unlock(lock: &xen_cpu_lock);
86 return;
87 }
88
89 idle_nums = xen_acpi_pad_idle_cpus(idle_nums)
90 ?: xen_acpi_pad_idle_cpus_num();
91 if (idle_nums >= 0)
92 acpi_evaluate_ost(handle, ACPI_PROCESSOR_AGGREGATOR_NOTIFY,
93 status_code: 0, status_buf: &param);
94 mutex_unlock(lock: &xen_cpu_lock);
95}
96
97static void acpi_pad_notify(acpi_handle handle, u32 event,
98 void *data)
99{
100 switch (event) {
101 case ACPI_PROCESSOR_AGGREGATOR_NOTIFY:
102 acpi_pad_handle_notify(handle);
103 break;
104 default:
105 pr_warn("Unsupported event [0x%x]\n", event);
106 break;
107 }
108}
109
110static int acpi_pad_add(struct acpi_device *device)
111{
112 acpi_status status;
113
114 strcpy(acpi_device_name(device), ACPI_PROCESSOR_AGGREGATOR_DEVICE_NAME);
115 strcpy(acpi_device_class(device), ACPI_PROCESSOR_AGGREGATOR_CLASS);
116
117 status = acpi_install_notify_handler(device: device->handle,
118 ACPI_DEVICE_NOTIFY, handler: acpi_pad_notify, context: device);
119 if (ACPI_FAILURE(status))
120 return -ENODEV;
121
122 return 0;
123}
124
125static void acpi_pad_remove(struct acpi_device *device)
126{
127 mutex_lock(&xen_cpu_lock);
128 xen_acpi_pad_idle_cpus(idle_nums: 0);
129 mutex_unlock(lock: &xen_cpu_lock);
130
131 acpi_remove_notify_handler(device: device->handle,
132 ACPI_DEVICE_NOTIFY, handler: acpi_pad_notify);
133}
134
135static const struct acpi_device_id pad_device_ids[] = {
136 {"ACPI000C", 0},
137 {"", 0},
138};
139
140static struct acpi_driver acpi_pad_driver = {
141 .name = "processor_aggregator",
142 .class = ACPI_PROCESSOR_AGGREGATOR_CLASS,
143 .ids = pad_device_ids,
144 .ops = {
145 .add = acpi_pad_add,
146 .remove = acpi_pad_remove,
147 },
148};
149
150static int __init xen_acpi_pad_init(void)
151{
152 /* Only DOM0 is responsible for Xen acpi pad */
153 if (!xen_initial_domain())
154 return -ENODEV;
155
156 /* Only Xen4.2 or later support Xen acpi pad */
157 if (!xen_running_on_version_or_later(major: 4, minor: 2))
158 return -ENODEV;
159
160 return acpi_bus_register_driver(driver: &acpi_pad_driver);
161}
162subsys_initcall(xen_acpi_pad_init);
163

source code of linux/drivers/xen/xen-acpi-pad.c