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); 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) 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(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(&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 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->handle, 118 ACPI_DEVICE_NOTIFY, acpi_pad_notify, 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(0); 129 mutex_unlock(&xen_cpu_lock); 130 131 acpi_remove_notify_handler(device->handle, 132 ACPI_DEVICE_NOTIFY, 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(4, 2)) 158 return -ENODEV; 159 160 return acpi_bus_register_driver(&acpi_pad_driver); 161 } 162 subsys_initcall(xen_acpi_pad_init); 163