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 30 static DEFINE_MUTEX(xen_cpu_lock); 31 32 static 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 43 static 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 */ 58 static 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 81 static 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, ¶m); 102 mutex_unlock(&xen_cpu_lock); 103 } 104 105 static 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 } 117 118 static 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 } 132 133 static 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 } 143 144 static const struct acpi_device_id pad_device_ids[] = { 145 {"ACPI000C", 0}, 146 {"", 0}, 147 }; 148 149 static 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 }; 158 159 static 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 } 171 subsys_initcall(xen_acpi_pad_init); 172