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/interface/version.h> 23 #include <xen/xen-ops.h> 24 #include <asm/xen/hypercall.h> 25 26 #define ACPI_PROCESSOR_AGGREGATOR_CLASS "acpi_pad" 27 #define ACPI_PROCESSOR_AGGREGATOR_DEVICE_NAME "Processor Aggregator" 28 #define ACPI_PROCESSOR_AGGREGATOR_NOTIFY 0x80 29 static DEFINE_MUTEX(xen_cpu_lock); 30 31 static int xen_acpi_pad_idle_cpus(unsigned int idle_nums) 32 { 33 struct xen_platform_op op; 34 35 op.cmd = XENPF_core_parking; 36 op.u.core_parking.type = XEN_CORE_PARKING_SET; 37 op.u.core_parking.idle_nums = idle_nums; 38 39 return HYPERVISOR_platform_op(&op); 40 } 41 42 static int xen_acpi_pad_idle_cpus_num(void) 43 { 44 struct xen_platform_op op; 45 46 op.cmd = XENPF_core_parking; 47 op.u.core_parking.type = XEN_CORE_PARKING_GET; 48 49 return HYPERVISOR_platform_op(&op) 50 ?: op.u.core_parking.idle_nums; 51 } 52 53 /* 54 * Query firmware how many CPUs should be idle 55 * return -1 on failure 56 */ 57 static int acpi_pad_pur(acpi_handle handle) 58 { 59 struct acpi_buffer buffer = {ACPI_ALLOCATE_BUFFER, NULL}; 60 union acpi_object *package; 61 int num = -1; 62 63 if (ACPI_FAILURE(acpi_evaluate_object(handle, "_PUR", NULL, &buffer))) 64 return num; 65 66 if (!buffer.length || !buffer.pointer) 67 return num; 68 69 package = buffer.pointer; 70 71 if (package->type == ACPI_TYPE_PACKAGE && 72 package->package.count == 2 && 73 package->package.elements[0].integer.value == 1) /* rev 1 */ 74 num = package->package.elements[1].integer.value; 75 76 kfree(buffer.pointer); 77 return num; 78 } 79 80 static void acpi_pad_handle_notify(acpi_handle handle) 81 { 82 int idle_nums; 83 struct acpi_buffer param = { 84 .length = 4, 85 .pointer = (void *)&idle_nums, 86 }; 87 88 89 mutex_lock(&xen_cpu_lock); 90 idle_nums = acpi_pad_pur(handle); 91 if (idle_nums < 0) { 92 mutex_unlock(&xen_cpu_lock); 93 return; 94 } 95 96 idle_nums = xen_acpi_pad_idle_cpus(idle_nums) 97 ?: xen_acpi_pad_idle_cpus_num(); 98 if (idle_nums >= 0) 99 acpi_evaluate_ost(handle, ACPI_PROCESSOR_AGGREGATOR_NOTIFY, 100 0, ¶m); 101 mutex_unlock(&xen_cpu_lock); 102 } 103 104 static void acpi_pad_notify(acpi_handle handle, u32 event, 105 void *data) 106 { 107 switch (event) { 108 case ACPI_PROCESSOR_AGGREGATOR_NOTIFY: 109 acpi_pad_handle_notify(handle); 110 break; 111 default: 112 pr_warn("Unsupported event [0x%x]\n", event); 113 break; 114 } 115 } 116 117 static int acpi_pad_add(struct acpi_device *device) 118 { 119 acpi_status status; 120 121 strcpy(acpi_device_name(device), ACPI_PROCESSOR_AGGREGATOR_DEVICE_NAME); 122 strcpy(acpi_device_class(device), ACPI_PROCESSOR_AGGREGATOR_CLASS); 123 124 status = acpi_install_notify_handler(device->handle, 125 ACPI_DEVICE_NOTIFY, acpi_pad_notify, device); 126 if (ACPI_FAILURE(status)) 127 return -ENODEV; 128 129 return 0; 130 } 131 132 static int acpi_pad_remove(struct acpi_device *device) 133 { 134 mutex_lock(&xen_cpu_lock); 135 xen_acpi_pad_idle_cpus(0); 136 mutex_unlock(&xen_cpu_lock); 137 138 acpi_remove_notify_handler(device->handle, 139 ACPI_DEVICE_NOTIFY, acpi_pad_notify); 140 return 0; 141 } 142 143 static const struct acpi_device_id pad_device_ids[] = { 144 {"ACPI000C", 0}, 145 {"", 0}, 146 }; 147 148 static struct acpi_driver acpi_pad_driver = { 149 .name = "processor_aggregator", 150 .class = ACPI_PROCESSOR_AGGREGATOR_CLASS, 151 .ids = pad_device_ids, 152 .ops = { 153 .add = acpi_pad_add, 154 .remove = acpi_pad_remove, 155 }, 156 }; 157 158 static int __init xen_acpi_pad_init(void) 159 { 160 /* Only DOM0 is responsible for Xen acpi pad */ 161 if (!xen_initial_domain()) 162 return -ENODEV; 163 164 /* Only Xen4.2 or later support Xen acpi pad */ 165 if (!xen_running_on_version_or_later(4, 2)) 166 return -ENODEV; 167 168 return acpi_bus_register_driver(&acpi_pad_driver); 169 } 170 subsys_initcall(xen_acpi_pad_init); 171