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1// SPDX-License-Identifier: GPL-2.0-only2/*3 * xen-acpi-pad.c - Xen pad interface4 *5 * Copyright (c) 2012, Intel Corporation.6 * Author: Liu, Jinsong <jinsong.liu@intel.com>7 */8 9#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt10 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 0x8022static 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);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)43 ?: op.u.core_parking.idle_nums;44}45 46/*47 * Query firmware how many CPUs should be idle48 * return -1 on failure49 */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(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(&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 0, ¶m);94 mutex_unlock(&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->handle,118 ACPI_DEVICE_NOTIFY, acpi_pad_notify, 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(0);129 mutex_unlock(&xen_cpu_lock);130 131 acpi_remove_notify_handler(device->handle,132 ACPI_DEVICE_NOTIFY, 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(4, 2))158 return -ENODEV;159 160 return acpi_bus_register_driver(&acpi_pad_driver);161}162subsys_initcall(xen_acpi_pad_init);163