drivers/xen/xen-acpi-pad.c

   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, &param);
 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);