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 #include <linux/kernel.h>
  18 #include <linux/types.h>
  19 #include <acpi/acpi_bus.h>
  20 #include <acpi/acpi_drivers.h>
  21 #include <asm/xen/hypercall.h>
  22 #include <xen/interface/version.h>
  23 #include <xen/xen-ops.h>
  24
  25 #define ACPI_PROCESSOR_AGGREGATOR_CLASS "acpi_pad"
  26 #define ACPI_PROCESSOR_AGGREGATOR_DEVICE_NAME "Processor Aggregator"
  27 #define ACPI_PROCESSOR_AGGREGATOR_NOTIFY 0x80
  28 static DEFINE_MUTEX(xen_cpu_lock);
  29
  30 static int xen_acpi_pad_idle_cpus(unsigned int idle_nums)
  31 {
  32         struct xen_platform_op op;
  33
  34         op.cmd = XENPF_core_parking;
  35         op.u.core_parking.type = XEN_CORE_PARKING_SET;
  36         op.u.core_parking.idle_nums = idle_nums;
  37
  38         return HYPERVISOR_dom0_op(&op);
  39 }
  40
  41 static int xen_acpi_pad_idle_cpus_num(void)
  42 {
  43         struct xen_platform_op op;
  44
  45         op.cmd = XENPF_core_parking;
  46         op.u.core_parking.type = XEN_CORE_PARKING_GET;
  47
  48         return HYPERVISOR_dom0_op(&op)
  49                ?: op.u.core_parking.idle_nums;
  50 }
  51
  52 /*
  53  * Query firmware how many CPUs should be idle
  54  * return -1 on failure
  55  */
  56 static int acpi_pad_pur(acpi_handle handle)
  57 {
  58         struct acpi_buffer buffer = {ACPI_ALLOCATE_BUFFER, NULL};
  59         union acpi_object *package;
  60         int num = -1;
  61
  62         if (ACPI_FAILURE(acpi_evaluate_object(handle, "_PUR", NULL, &buffer)))
  63                 return num;
  64
  65         if (!buffer.length || !buffer.pointer)
  66                 return num;
  67
  68         package = buffer.pointer;
  69
  70         if (package->type == ACPI_TYPE_PACKAGE &&
  71                 package->package.count == 2 &&
  72                 package->package.elements[0].integer.value == 1) /* rev 1 */
  73                 num = package->package.elements[1].integer.value;
  74
  75         kfree(buffer.pointer);
  76         return num;
  77 }
  78
  79 /* Notify firmware how many CPUs are idle */
  80 static void acpi_pad_ost(acpi_handle handle, int stat,
  81         uint32_t idle_nums)
  82 {
  83         union acpi_object params[3] = {
  84                 {.type = ACPI_TYPE_INTEGER,},
  85                 {.type = ACPI_TYPE_INTEGER,},
  86                 {.type = ACPI_TYPE_BUFFER,},
  87         };
  88         struct acpi_object_list arg_list = {3, params};
  89
  90         params[0].integer.value = ACPI_PROCESSOR_AGGREGATOR_NOTIFY;
  91         params[1].integer.value =  stat;
  92         params[2].buffer.length = 4;
  93         params[2].buffer.pointer = (void *)&idle_nums;
  94         acpi_evaluate_object(handle, "_OST", &arg_list, NULL);
  95 }
  96
  97 static void acpi_pad_handle_notify(acpi_handle handle)
  98 {
  99         int idle_nums;
 100
 101         mutex_lock(&xen_cpu_lock);
 102         idle_nums = acpi_pad_pur(handle);
 103         if (idle_nums < 0) {
 104                 mutex_unlock(&xen_cpu_lock);
 105                 return;
 106         }
 107
 108         idle_nums = xen_acpi_pad_idle_cpus(idle_nums)
 109                     ?: xen_acpi_pad_idle_cpus_num();
 110         if (idle_nums >= 0)
 111                 acpi_pad_ost(handle, 0, idle_nums);
 112         mutex_unlock(&xen_cpu_lock);
 113 }
 114
 115 static void acpi_pad_notify(acpi_handle handle, u32 event,
 116         void *data)
 117 {
 118         switch (event) {
 119         case ACPI_PROCESSOR_AGGREGATOR_NOTIFY:
 120                 acpi_pad_handle_notify(handle);
 121                 break;
 122         default:
 123                 pr_warn("Unsupported event [0x%x]\n", event);
 124                 break;
 125         }
 126 }
 127
 128 static int acpi_pad_add(struct acpi_device *device)
 129 {
 130         acpi_status status;
 131
 132         strcpy(acpi_device_name(device), ACPI_PROCESSOR_AGGREGATOR_DEVICE_NAME);
 133         strcpy(acpi_device_class(device), ACPI_PROCESSOR_AGGREGATOR_CLASS);
 134
 135         status = acpi_install_notify_handler(device->handle,
 136                 ACPI_DEVICE_NOTIFY, acpi_pad_notify, device);
 137         if (ACPI_FAILURE(status))
 138                 return -ENODEV;
 139
 140         return 0;
 141 }
 142
 143 static int acpi_pad_remove(struct acpi_device *device)
 144 {
 145         mutex_lock(&xen_cpu_lock);
 146         xen_acpi_pad_idle_cpus(0);
 147         mutex_unlock(&xen_cpu_lock);
 148
 149         acpi_remove_notify_handler(device->handle,
 150                 ACPI_DEVICE_NOTIFY, acpi_pad_notify);
 151         return 0;
 152 }
 153
 154 static const struct acpi_device_id pad_device_ids[] = {
 155         {"ACPI000C", 0},
 156         {"", 0},
 157 };
 158
 159 static struct acpi_driver acpi_pad_driver = {
 160         .name = "processor_aggregator",
 161         .class = ACPI_PROCESSOR_AGGREGATOR_CLASS,
 162         .ids = pad_device_ids,
 163         .ops = {
 164                 .add = acpi_pad_add,
 165                 .remove = acpi_pad_remove,
 166         },
 167 };
 168
 169 static int __init xen_acpi_pad_init(void)
 170 {
 171         /* Only DOM0 is responsible for Xen acpi pad */
 172         if (!xen_initial_domain())
 173                 return -ENODEV;
 174
 175         /* Only Xen4.2 or later support Xen acpi pad */
 176         if (!xen_running_on_version_or_later(4, 2))
 177                 return -ENODEV;
 178
 179         return acpi_bus_register_driver(&acpi_pad_driver);
 180 }
 181 subsys_initcall(xen_acpi_pad_init);