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 |
22 | static DEFINE_MUTEX(xen_cpu_lock); |
23 | |
24 | static 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 | |
35 | static 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 | */ |
50 | static 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 | |
73 | static 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: ¶m); |
94 | mutex_unlock(lock: &xen_cpu_lock); |
95 | } |
96 | |
97 | static 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 | |
110 | static 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 | |
125 | static 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 | |
135 | static const struct acpi_device_id pad_device_ids[] = { |
136 | {"ACPI000C" , 0}, |
137 | {"" , 0}, |
138 | }; |
139 | |
140 | static 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 | |
150 | static 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 | } |
162 | subsys_initcall(xen_acpi_pad_init); |
163 | |