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 <acpi/acpi_bus.h> 22 #include <acpi/acpi_drivers.h> 23 #include <asm/xen/hypercall.h> 24 #include <xen/interface/version.h> 25 #include <xen/xen-ops.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_dom0_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_dom0_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 /* Notify firmware how many CPUs are idle */ 82 static void acpi_pad_ost(acpi_handle handle, int stat, 83 uint32_t idle_nums) 84 { 85 union acpi_object params[3] = { 86 {.type = ACPI_TYPE_INTEGER,}, 87 {.type = ACPI_TYPE_INTEGER,}, 88 {.type = ACPI_TYPE_BUFFER,}, 89 }; 90 struct acpi_object_list arg_list = {3, params}; 91 92 params[0].integer.value = ACPI_PROCESSOR_AGGREGATOR_NOTIFY; 93 params[1].integer.value = stat; 94 params[2].buffer.length = 4; 95 params[2].buffer.pointer = (void *)&idle_nums; 96 acpi_evaluate_object(handle, "_OST", &arg_list, NULL); 97 } 98 99 static void acpi_pad_handle_notify(acpi_handle handle) 100 { 101 int idle_nums; 102 103 mutex_lock(&xen_cpu_lock); 104 idle_nums = acpi_pad_pur(handle); 105 if (idle_nums < 0) { 106 mutex_unlock(&xen_cpu_lock); 107 return; 108 } 109 110 idle_nums = xen_acpi_pad_idle_cpus(idle_nums) 111 ?: xen_acpi_pad_idle_cpus_num(); 112 if (idle_nums >= 0) 113 acpi_pad_ost(handle, 0, idle_nums); 114 mutex_unlock(&xen_cpu_lock); 115 } 116 117 static void acpi_pad_notify(acpi_handle handle, u32 event, 118 void *data) 119 { 120 switch (event) { 121 case ACPI_PROCESSOR_AGGREGATOR_NOTIFY: 122 acpi_pad_handle_notify(handle); 123 break; 124 default: 125 pr_warn("Unsupported event [0x%x]\n", event); 126 break; 127 } 128 } 129 130 static int acpi_pad_add(struct acpi_device *device) 131 { 132 acpi_status status; 133 134 strcpy(acpi_device_name(device), ACPI_PROCESSOR_AGGREGATOR_DEVICE_NAME); 135 strcpy(acpi_device_class(device), ACPI_PROCESSOR_AGGREGATOR_CLASS); 136 137 status = acpi_install_notify_handler(device->handle, 138 ACPI_DEVICE_NOTIFY, acpi_pad_notify, device); 139 if (ACPI_FAILURE(status)) 140 return -ENODEV; 141 142 return 0; 143 } 144 145 static int acpi_pad_remove(struct acpi_device *device) 146 { 147 mutex_lock(&xen_cpu_lock); 148 xen_acpi_pad_idle_cpus(0); 149 mutex_unlock(&xen_cpu_lock); 150 151 acpi_remove_notify_handler(device->handle, 152 ACPI_DEVICE_NOTIFY, acpi_pad_notify); 153 return 0; 154 } 155 156 static const struct acpi_device_id pad_device_ids[] = { 157 {"ACPI000C", 0}, 158 {"", 0}, 159 }; 160 161 static struct acpi_driver acpi_pad_driver = { 162 .name = "processor_aggregator", 163 .class = ACPI_PROCESSOR_AGGREGATOR_CLASS, 164 .ids = pad_device_ids, 165 .ops = { 166 .add = acpi_pad_add, 167 .remove = acpi_pad_remove, 168 }, 169 }; 170 171 static int __init xen_acpi_pad_init(void) 172 { 173 /* Only DOM0 is responsible for Xen acpi pad */ 174 if (!xen_initial_domain()) 175 return -ENODEV; 176 177 /* Only Xen4.2 or later support Xen acpi pad */ 178 if (!xen_running_on_version_or_later(4, 2)) 179 return -ENODEV; 180 181 return acpi_bus_register_driver(&acpi_pad_driver); 182 } 183 subsys_initcall(xen_acpi_pad_init); 184