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/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, &param);
 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);