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// SPDX-License-Identifier: GPL-2.0-only
/*
* xen-acpi-pad.c - Xen pad interface
*
* Copyright (c) 2012, Intel Corporation.
* Author: Liu, Jinsong <jinsong.liu@intel.com>
*/
#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
#include <linux/kernel.h>
#include <linux/types.h>
#include <linux/acpi.h>
#include <xen/xen.h>
#include <xen/interface/version.h>
#include <xen/xen-ops.h>
#include <asm/xen/hypercall.h>
#define ACPI_PROCESSOR_AGGREGATOR_CLASS "acpi_pad"
#define ACPI_PROCESSOR_AGGREGATOR_DEVICE_NAME "Processor Aggregator"
#define ACPI_PROCESSOR_AGGREGATOR_NOTIFY 0x80
static DEFINE_MUTEX(xen_cpu_lock);
static int xen_acpi_pad_idle_cpus(unsigned int idle_nums)
{
struct xen_platform_op op;
op.cmd = XENPF_core_parking;
op.u.core_parking.type = XEN_CORE_PARKING_SET;
op.u.core_parking.idle_nums = idle_nums;
return HYPERVISOR_platform_op(&op);
}
static int xen_acpi_pad_idle_cpus_num(void)
{
struct xen_platform_op op;
op.cmd = XENPF_core_parking;
op.u.core_parking.type = XEN_CORE_PARKING_GET;
return HYPERVISOR_platform_op(&op)
?: op.u.core_parking.idle_nums;
}
/*
* Query firmware how many CPUs should be idle
* return -1 on failure
*/
static int acpi_pad_pur(acpi_handle handle)
{
struct acpi_buffer buffer = {ACPI_ALLOCATE_BUFFER, NULL};
union acpi_object *package;
int num = -1;
if (ACPI_FAILURE(acpi_evaluate_object(handle, "_PUR", NULL, &buffer)))
return num;
if (!buffer.length || !buffer.pointer)
return num;
package = buffer.pointer;
if (package->type == ACPI_TYPE_PACKAGE &&
package->package.count == 2 &&
package->package.elements[0].integer.value == 1) /* rev 1 */
num = package->package.elements[1].integer.value;
kfree(buffer.pointer);
return num;
}
static void acpi_pad_handle_notify(acpi_handle handle)
{
int idle_nums;
struct acpi_buffer param = {
.length = 4,
.pointer = (void *)&idle_nums,
};
mutex_lock(&xen_cpu_lock);
idle_nums = acpi_pad_pur(handle);
if (idle_nums < 0) {
mutex_unlock(&xen_cpu_lock);
return;
}
idle_nums = xen_acpi_pad_idle_cpus(idle_nums)
?: xen_acpi_pad_idle_cpus_num();
if (idle_nums >= 0)
acpi_evaluate_ost(handle, ACPI_PROCESSOR_AGGREGATOR_NOTIFY,
0, ¶m);
mutex_unlock(&xen_cpu_lock);
}
static void acpi_pad_notify(acpi_handle handle, u32 event,
void *data)
{
switch (event) {
case ACPI_PROCESSOR_AGGREGATOR_NOTIFY:
acpi_pad_handle_notify(handle);
break;
default:
pr_warn("Unsupported event [0x%x]\n", event);
break;
}
}
static int acpi_pad_add(struct acpi_device *device)
{
acpi_status status;
strcpy(acpi_device_name(device), ACPI_PROCESSOR_AGGREGATOR_DEVICE_NAME);
strcpy(acpi_device_class(device), ACPI_PROCESSOR_AGGREGATOR_CLASS);
status = acpi_install_notify_handler(device->handle,
ACPI_DEVICE_NOTIFY, acpi_pad_notify, device);
if (ACPI_FAILURE(status))
return -ENODEV;
return 0;
}
static void acpi_pad_remove(struct acpi_device *device)
{
mutex_lock(&xen_cpu_lock);
xen_acpi_pad_idle_cpus(0);
mutex_unlock(&xen_cpu_lock);
acpi_remove_notify_handler(device->handle,
ACPI_DEVICE_NOTIFY, acpi_pad_notify);
}
static const struct acpi_device_id pad_device_ids[] = {
{"ACPI000C", 0},
{"", 0},
};
static struct acpi_driver acpi_pad_driver = {
.name = "processor_aggregator",
.class = ACPI_PROCESSOR_AGGREGATOR_CLASS,
.ids = pad_device_ids,
.ops = {
.add = acpi_pad_add,
.remove = acpi_pad_remove,
},
};
static int __init xen_acpi_pad_init(void)
{
/* Only DOM0 is responsible for Xen acpi pad */
if (!xen_initial_domain())
return -ENODEV;
/* Only Xen4.2 or later support Xen acpi pad */
if (!xen_running_on_version_or_later(4, 2))
return -ENODEV;
return acpi_bus_register_driver(&acpi_pad_driver);
}
subsys_initcall(xen_acpi_pad_init);
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