Right now we forcibly clear ASPM state on all devices if the BIOS indicates that the feature isn't supported. Based on the Microsoft presentation "PCI Express In Depth for Windows Vista and Beyond", I'm starting to think that this may be an error. The implication is that unless the platform grants full control via _OSC, Windows will not touch any PCIe features - including ASPM. In that case clearing ASPM state would be an error unless the platform has granted us that control. This patch reworks the ASPM disabling code such that the actual clearing of state is triggered by a successful handoff of PCIe control to the OS. The general ASPM code undergoes some changes in order to ensure that the ability to clear the bits isn't overridden by ASPM having already been disabled. Further, this theoretically now allows for situations where only a subset of PCIe roots hand over control, leaving the others in the BIOS state. It's difficult to know for sure that this is the right thing to do - there's zero public documentation on the interaction between all of these components. But enough vendors enable ASPM on platforms and then set this bit that it seems likely that they're expecting the OS to leave them alone. Measured to save around 5W on an idle Thinkpad X220. Signed-off-by: Matthew Garrett <mjg@redhat.com> Signed-off-by: Jesse Barnes <jbarnes@virtuousgeek.org>
408 lines
10 KiB
C
408 lines
10 KiB
C
/*
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* File: pci-acpi.c
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* Purpose: Provide PCI support in ACPI
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*
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* Copyright (C) 2005 David Shaohua Li <shaohua.li@intel.com>
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* Copyright (C) 2004 Tom Long Nguyen <tom.l.nguyen@intel.com>
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* Copyright (C) 2004 Intel Corp.
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*/
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#include <linux/delay.h>
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#include <linux/init.h>
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#include <linux/pci.h>
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#include <linux/module.h>
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#include <linux/pci-aspm.h>
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#include <acpi/acpi.h>
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#include <acpi/acpi_bus.h>
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#include <linux/pci-acpi.h>
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#include <linux/pm_runtime.h>
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#include "pci.h"
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static DEFINE_MUTEX(pci_acpi_pm_notify_mtx);
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/**
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* pci_acpi_wake_bus - Wake-up notification handler for root buses.
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* @handle: ACPI handle of a device the notification is for.
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* @event: Type of the signaled event.
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* @context: PCI root bus to wake up devices on.
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*/
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static void pci_acpi_wake_bus(acpi_handle handle, u32 event, void *context)
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{
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struct pci_bus *pci_bus = context;
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if (event == ACPI_NOTIFY_DEVICE_WAKE && pci_bus)
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pci_pme_wakeup_bus(pci_bus);
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}
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/**
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* pci_acpi_wake_dev - Wake-up notification handler for PCI devices.
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* @handle: ACPI handle of a device the notification is for.
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* @event: Type of the signaled event.
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* @context: PCI device object to wake up.
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*/
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static void pci_acpi_wake_dev(acpi_handle handle, u32 event, void *context)
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{
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struct pci_dev *pci_dev = context;
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if (event == ACPI_NOTIFY_DEVICE_WAKE && pci_dev) {
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if (pci_dev->pme_poll)
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pci_dev->pme_poll = false;
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pci_wakeup_event(pci_dev);
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pci_check_pme_status(pci_dev);
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pm_runtime_resume(&pci_dev->dev);
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if (pci_dev->subordinate)
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pci_pme_wakeup_bus(pci_dev->subordinate);
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}
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}
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/**
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* add_pm_notifier - Register PM notifier for given ACPI device.
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* @dev: ACPI device to add the notifier for.
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* @context: PCI device or bus to check for PME status if an event is signaled.
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*
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* NOTE: @dev need not be a run-wake or wake-up device to be a valid source of
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* PM wake-up events. For example, wake-up events may be generated for bridges
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* if one of the devices below the bridge is signaling PME, even if the bridge
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* itself doesn't have a wake-up GPE associated with it.
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*/
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static acpi_status add_pm_notifier(struct acpi_device *dev,
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acpi_notify_handler handler,
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void *context)
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{
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acpi_status status = AE_ALREADY_EXISTS;
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mutex_lock(&pci_acpi_pm_notify_mtx);
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if (dev->wakeup.flags.notifier_present)
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goto out;
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status = acpi_install_notify_handler(dev->handle,
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ACPI_SYSTEM_NOTIFY,
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handler, context);
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if (ACPI_FAILURE(status))
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goto out;
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dev->wakeup.flags.notifier_present = true;
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out:
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mutex_unlock(&pci_acpi_pm_notify_mtx);
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return status;
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}
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/**
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* remove_pm_notifier - Unregister PM notifier from given ACPI device.
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* @dev: ACPI device to remove the notifier from.
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*/
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static acpi_status remove_pm_notifier(struct acpi_device *dev,
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acpi_notify_handler handler)
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{
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acpi_status status = AE_BAD_PARAMETER;
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mutex_lock(&pci_acpi_pm_notify_mtx);
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if (!dev->wakeup.flags.notifier_present)
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goto out;
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status = acpi_remove_notify_handler(dev->handle,
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ACPI_SYSTEM_NOTIFY,
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handler);
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if (ACPI_FAILURE(status))
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goto out;
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dev->wakeup.flags.notifier_present = false;
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out:
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mutex_unlock(&pci_acpi_pm_notify_mtx);
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return status;
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}
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/**
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* pci_acpi_add_bus_pm_notifier - Register PM notifier for given PCI bus.
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* @dev: ACPI device to add the notifier for.
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* @pci_bus: PCI bus to walk checking for PME status if an event is signaled.
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*/
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acpi_status pci_acpi_add_bus_pm_notifier(struct acpi_device *dev,
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struct pci_bus *pci_bus)
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{
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return add_pm_notifier(dev, pci_acpi_wake_bus, pci_bus);
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}
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/**
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* pci_acpi_remove_bus_pm_notifier - Unregister PCI bus PM notifier.
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* @dev: ACPI device to remove the notifier from.
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*/
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acpi_status pci_acpi_remove_bus_pm_notifier(struct acpi_device *dev)
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{
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return remove_pm_notifier(dev, pci_acpi_wake_bus);
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}
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/**
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* pci_acpi_add_pm_notifier - Register PM notifier for given PCI device.
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* @dev: ACPI device to add the notifier for.
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* @pci_dev: PCI device to check for the PME status if an event is signaled.
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*/
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acpi_status pci_acpi_add_pm_notifier(struct acpi_device *dev,
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struct pci_dev *pci_dev)
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{
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return add_pm_notifier(dev, pci_acpi_wake_dev, pci_dev);
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}
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/**
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* pci_acpi_remove_pm_notifier - Unregister PCI device PM notifier.
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* @dev: ACPI device to remove the notifier from.
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*/
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acpi_status pci_acpi_remove_pm_notifier(struct acpi_device *dev)
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{
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return remove_pm_notifier(dev, pci_acpi_wake_dev);
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}
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/*
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* _SxD returns the D-state with the highest power
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* (lowest D-state number) supported in the S-state "x".
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*
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* If the devices does not have a _PRW
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* (Power Resources for Wake) supporting system wakeup from "x"
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* then the OS is free to choose a lower power (higher number
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* D-state) than the return value from _SxD.
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*
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* But if _PRW is enabled at S-state "x", the OS
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* must not choose a power lower than _SxD --
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* unless the device has an _SxW method specifying
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* the lowest power (highest D-state number) the device
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* may enter while still able to wake the system.
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*
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* ie. depending on global OS policy:
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*
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* if (_PRW at S-state x)
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* choose from highest power _SxD to lowest power _SxW
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* else // no _PRW at S-state x
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* choose highest power _SxD or any lower power
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*/
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static pci_power_t acpi_pci_choose_state(struct pci_dev *pdev)
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{
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int acpi_state;
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acpi_state = acpi_pm_device_sleep_state(&pdev->dev, NULL);
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if (acpi_state < 0)
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return PCI_POWER_ERROR;
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switch (acpi_state) {
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case ACPI_STATE_D0:
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return PCI_D0;
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case ACPI_STATE_D1:
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return PCI_D1;
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case ACPI_STATE_D2:
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return PCI_D2;
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case ACPI_STATE_D3:
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return PCI_D3hot;
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case ACPI_STATE_D3_COLD:
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return PCI_D3cold;
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}
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return PCI_POWER_ERROR;
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}
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static bool acpi_pci_power_manageable(struct pci_dev *dev)
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{
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acpi_handle handle = DEVICE_ACPI_HANDLE(&dev->dev);
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return handle ? acpi_bus_power_manageable(handle) : false;
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}
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static int acpi_pci_set_power_state(struct pci_dev *dev, pci_power_t state)
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{
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acpi_handle handle = DEVICE_ACPI_HANDLE(&dev->dev);
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acpi_handle tmp;
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static const u8 state_conv[] = {
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[PCI_D0] = ACPI_STATE_D0,
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[PCI_D1] = ACPI_STATE_D1,
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[PCI_D2] = ACPI_STATE_D2,
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[PCI_D3hot] = ACPI_STATE_D3,
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[PCI_D3cold] = ACPI_STATE_D3
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};
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int error = -EINVAL;
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/* If the ACPI device has _EJ0, ignore the device */
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if (!handle || ACPI_SUCCESS(acpi_get_handle(handle, "_EJ0", &tmp)))
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return -ENODEV;
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switch (state) {
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case PCI_D0:
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case PCI_D1:
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case PCI_D2:
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case PCI_D3hot:
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case PCI_D3cold:
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error = acpi_bus_set_power(handle, state_conv[state]);
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}
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if (!error)
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dev_printk(KERN_INFO, &dev->dev,
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"power state changed by ACPI to D%d\n", state);
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return error;
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}
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static bool acpi_pci_can_wakeup(struct pci_dev *dev)
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{
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acpi_handle handle = DEVICE_ACPI_HANDLE(&dev->dev);
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return handle ? acpi_bus_can_wakeup(handle) : false;
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}
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static void acpi_pci_propagate_wakeup_enable(struct pci_bus *bus, bool enable)
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{
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while (bus->parent) {
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if (!acpi_pm_device_sleep_wake(&bus->self->dev, enable))
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return;
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bus = bus->parent;
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}
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/* We have reached the root bus. */
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if (bus->bridge)
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acpi_pm_device_sleep_wake(bus->bridge, enable);
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}
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static int acpi_pci_sleep_wake(struct pci_dev *dev, bool enable)
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{
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if (acpi_pci_can_wakeup(dev))
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return acpi_pm_device_sleep_wake(&dev->dev, enable);
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acpi_pci_propagate_wakeup_enable(dev->bus, enable);
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return 0;
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}
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/**
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* acpi_dev_run_wake - Enable/disable wake-up for given device.
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* @phys_dev: Device to enable/disable the platform to wake-up the system for.
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* @enable: Whether enable or disable the wake-up functionality.
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*
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* Find the ACPI device object corresponding to @pci_dev and try to
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* enable/disable the GPE associated with it.
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*/
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static int acpi_dev_run_wake(struct device *phys_dev, bool enable)
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{
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struct acpi_device *dev;
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acpi_handle handle;
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if (!device_run_wake(phys_dev))
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return -EINVAL;
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handle = DEVICE_ACPI_HANDLE(phys_dev);
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if (!handle || ACPI_FAILURE(acpi_bus_get_device(handle, &dev))) {
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dev_dbg(phys_dev, "ACPI handle has no context in %s!\n",
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__func__);
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return -ENODEV;
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}
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if (enable) {
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acpi_enable_wakeup_device_power(dev, ACPI_STATE_S0);
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acpi_enable_gpe(dev->wakeup.gpe_device, dev->wakeup.gpe_number);
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} else {
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acpi_disable_gpe(dev->wakeup.gpe_device, dev->wakeup.gpe_number);
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acpi_disable_wakeup_device_power(dev);
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}
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return 0;
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}
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static void acpi_pci_propagate_run_wake(struct pci_bus *bus, bool enable)
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{
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while (bus->parent) {
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struct pci_dev *bridge = bus->self;
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if (bridge->pme_interrupt)
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return;
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if (!acpi_dev_run_wake(&bridge->dev, enable))
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return;
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bus = bus->parent;
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}
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/* We have reached the root bus. */
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if (bus->bridge)
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acpi_dev_run_wake(bus->bridge, enable);
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}
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static int acpi_pci_run_wake(struct pci_dev *dev, bool enable)
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{
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if (dev->pme_interrupt)
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return 0;
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if (!acpi_dev_run_wake(&dev->dev, enable))
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return 0;
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acpi_pci_propagate_run_wake(dev->bus, enable);
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return 0;
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}
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static struct pci_platform_pm_ops acpi_pci_platform_pm = {
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.is_manageable = acpi_pci_power_manageable,
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.set_state = acpi_pci_set_power_state,
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.choose_state = acpi_pci_choose_state,
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.can_wakeup = acpi_pci_can_wakeup,
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.sleep_wake = acpi_pci_sleep_wake,
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.run_wake = acpi_pci_run_wake,
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};
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/* ACPI bus type */
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static int acpi_pci_find_device(struct device *dev, acpi_handle *handle)
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{
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struct pci_dev * pci_dev;
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u64 addr;
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pci_dev = to_pci_dev(dev);
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/* Please ref to ACPI spec for the syntax of _ADR */
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addr = (PCI_SLOT(pci_dev->devfn) << 16) | PCI_FUNC(pci_dev->devfn);
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*handle = acpi_get_child(DEVICE_ACPI_HANDLE(dev->parent), addr);
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if (!*handle)
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return -ENODEV;
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return 0;
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}
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static int acpi_pci_find_root_bridge(struct device *dev, acpi_handle *handle)
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{
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int num;
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unsigned int seg, bus;
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/*
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* The string should be the same as root bridge's name
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* Please look at 'pci_scan_bus_parented'
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*/
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num = sscanf(dev_name(dev), "pci%04x:%02x", &seg, &bus);
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if (num != 2)
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return -ENODEV;
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*handle = acpi_get_pci_rootbridge_handle(seg, bus);
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if (!*handle)
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return -ENODEV;
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return 0;
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}
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static struct acpi_bus_type acpi_pci_bus = {
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.bus = &pci_bus_type,
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.find_device = acpi_pci_find_device,
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.find_bridge = acpi_pci_find_root_bridge,
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};
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static int __init acpi_pci_init(void)
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{
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int ret;
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if (acpi_gbl_FADT.boot_flags & ACPI_FADT_NO_MSI) {
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printk(KERN_INFO"ACPI FADT declares the system doesn't support MSI, so disable it\n");
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pci_no_msi();
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}
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if (acpi_gbl_FADT.boot_flags & ACPI_FADT_NO_ASPM) {
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printk(KERN_INFO"ACPI FADT declares the system doesn't support PCIe ASPM, so disable it\n");
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pcie_no_aspm();
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}
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ret = register_acpi_bus_type(&acpi_pci_bus);
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if (ret)
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return 0;
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pci_set_platform_pm(&acpi_pci_platform_pm);
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return 0;
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}
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arch_initcall(acpi_pci_init);
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