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87d0f2a553
This addresses deadlocks in these common cases in hierarchies containing
two switches:
- All involved ports are runtime suspended and they are unplugged. This
can happen easily if the drivers involved automatically enable runtime
PM (xHCI for example does that).
- System is suspended (e.g., closing the lid on a laptop) with a dock +
something else connected, and the dock is unplugged while suspended.
These cases lead to the following deadlock:
INFO: task irq/126-pciehp:198 blocked for more than 120 seconds.
irq/126-pciehp D 0 198 2 0x80000000
Call Trace:
schedule+0x2c/0x80
schedule_timeout+0x246/0x350
wait_for_completion+0xb7/0x140
kthread_stop+0x49/0x110
free_irq+0x32/0x70
pcie_shutdown_notification+0x2f/0x50
pciehp_remove+0x27/0x50
pcie_port_remove_service+0x36/0x50
device_release_driver+0x12/0x20
bus_remove_device+0xec/0x160
device_del+0x13b/0x350
device_unregister+0x1a/0x60
remove_iter+0x1e/0x30
device_for_each_child+0x56/0x90
pcie_port_device_remove+0x22/0x40
pcie_portdrv_remove+0x20/0x60
pci_device_remove+0x3e/0xc0
device_release_driver_internal+0x18c/0x250
device_release_driver+0x12/0x20
pci_stop_bus_device+0x6f/0x90
pci_stop_bus_device+0x31/0x90
pci_stop_and_remove_bus_device+0x12/0x20
pciehp_unconfigure_device+0x88/0x140
pciehp_disable_slot+0x6a/0x110
pciehp_handle_presence_or_link_change+0x263/0x400
pciehp_ist+0x1c9/0x1d0
irq_thread_fn+0x24/0x60
irq_thread+0xeb/0x190
kthread+0x120/0x140
INFO: task irq/190-pciehp:2288 blocked for more than 120 seconds.
irq/190-pciehp D 0 2288 2 0x80000000
Call Trace:
__schedule+0x2a2/0x880
schedule+0x2c/0x80
schedule_preempt_disabled+0xe/0x10
mutex_lock+0x2c/0x30
pci_lock_rescan_remove+0x15/0x20
pciehp_unconfigure_device+0x4d/0x140
pciehp_disable_slot+0x6a/0x110
pciehp_handle_presence_or_link_change+0x263/0x400
pciehp_ist+0x1c9/0x1d0
irq_thread_fn+0x24/0x60
irq_thread+0xeb/0x190
kthread+0x120/0x140
What happens here is that the whole hierarchy is runtime resumed and the
parent PCIe downstream port, which got the hot-remove event, starts
removing devices below it, taking pci_lock_rescan_remove() lock. When the
child PCIe port is runtime resumed it calls pciehp_check_presence() which
ends up calling pciehp_card_present() and pciehp_check_link_active(). Both
of these use pcie_capability_read_word(), which notices that the underlying
device is already gone and returns PCIBIOS_DEVICE_NOT_FOUND with the
capability value set to 0. When pciehp gets this value it thinks that its
child device is also hot-removed and schedules its IRQ thread to handle the
event.
The deadlock happens when the child's IRQ thread runs and tries to acquire
pci_lock_rescan_remove() which is already taken by the parent and the
parent waits for the child's IRQ thread to finish.
Prevent this from happening by checking the return value of
pcie_capability_read_word() and if it is PCIBIOS_DEVICE_NOT_FOUND stop
performing any hot-removal activities.
[bhelgaas: add common scenarios to commit log]
Link: https://lore.kernel.org/r/20191029170022.57528-2-mika.westerberg@linux.intel.com
Tested-by: Kai-Heng Feng <kai.heng.feng@canonical.com>
Signed-off-by: Mika Westerberg <mika.westerberg@linux.intel.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
201 lines
8.0 KiB
C
201 lines
8.0 KiB
C
/* SPDX-License-Identifier: GPL-2.0+ */
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/*
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* PCI Express Hot Plug Controller Driver
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*
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* Copyright (C) 1995,2001 Compaq Computer Corporation
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* Copyright (C) 2001 Greg Kroah-Hartman (greg@kroah.com)
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* Copyright (C) 2001 IBM Corp.
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* Copyright (C) 2003-2004 Intel Corporation
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*
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* All rights reserved.
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*
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* Send feedback to <greg@kroah.com>, <kristen.c.accardi@intel.com>
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*
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*/
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#ifndef _PCIEHP_H
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#define _PCIEHP_H
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#include <linux/types.h>
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#include <linux/pci.h>
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#include <linux/pci_hotplug.h>
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#include <linux/delay.h>
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#include <linux/mutex.h>
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#include <linux/rwsem.h>
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#include <linux/workqueue.h>
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#include "../pcie/portdrv.h"
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extern bool pciehp_poll_mode;
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extern int pciehp_poll_time;
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/*
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* Set CONFIG_DYNAMIC_DEBUG=y and boot with 'dyndbg="file pciehp* +p"' to
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* enable debug messages.
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*/
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#define ctrl_dbg(ctrl, format, arg...) \
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pci_dbg(ctrl->pcie->port, format, ## arg)
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#define ctrl_err(ctrl, format, arg...) \
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pci_err(ctrl->pcie->port, format, ## arg)
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#define ctrl_info(ctrl, format, arg...) \
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pci_info(ctrl->pcie->port, format, ## arg)
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#define ctrl_warn(ctrl, format, arg...) \
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pci_warn(ctrl->pcie->port, format, ## arg)
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#define SLOT_NAME_SIZE 10
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/**
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* struct controller - PCIe hotplug controller
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* @pcie: pointer to the controller's PCIe port service device
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* @slot_cap: cached copy of the Slot Capabilities register
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* @slot_ctrl: cached copy of the Slot Control register
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* @ctrl_lock: serializes writes to the Slot Control register
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* @cmd_started: jiffies when the Slot Control register was last written;
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* the next write is allowed 1 second later, absent a Command Completed
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* interrupt (PCIe r4.0, sec 6.7.3.2)
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* @cmd_busy: flag set on Slot Control register write, cleared by IRQ handler
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* on reception of a Command Completed event
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* @queue: wait queue to wake up on reception of a Command Completed event,
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* used for synchronous writes to the Slot Control register
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* @pending_events: used by the IRQ handler to save events retrieved from the
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* Slot Status register for later consumption by the IRQ thread
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* @notification_enabled: whether the IRQ was requested successfully
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* @power_fault_detected: whether a power fault was detected by the hardware
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* that has not yet been cleared by the user
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* @poll_thread: thread to poll for slot events if no IRQ is available,
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* enabled with pciehp_poll_mode module parameter
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* @state: current state machine position
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* @state_lock: protects reads and writes of @state;
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* protects scheduling, execution and cancellation of @button_work
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* @button_work: work item to turn the slot on or off after 5 seconds
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* in response to an Attention Button press
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* @hotplug_slot: structure registered with the PCI hotplug core
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* @reset_lock: prevents access to the Data Link Layer Link Active bit in the
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* Link Status register and to the Presence Detect State bit in the Slot
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* Status register during a slot reset which may cause them to flap
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* @ist_running: flag to keep user request waiting while IRQ thread is running
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* @request_result: result of last user request submitted to the IRQ thread
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* @requester: wait queue to wake up on completion of user request,
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* used for synchronous slot enable/disable request via sysfs
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*
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* PCIe hotplug has a 1:1 relationship between controller and slot, hence
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* unlike other drivers, the two aren't represented by separate structures.
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*/
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struct controller {
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struct pcie_device *pcie;
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u32 slot_cap; /* capabilities and quirks */
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u16 slot_ctrl; /* control register access */
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struct mutex ctrl_lock;
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unsigned long cmd_started;
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unsigned int cmd_busy:1;
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wait_queue_head_t queue;
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atomic_t pending_events; /* event handling */
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unsigned int notification_enabled:1;
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unsigned int power_fault_detected;
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struct task_struct *poll_thread;
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u8 state; /* state machine */
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struct mutex state_lock;
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struct delayed_work button_work;
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struct hotplug_slot hotplug_slot; /* hotplug core interface */
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struct rw_semaphore reset_lock;
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unsigned int ist_running;
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int request_result;
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wait_queue_head_t requester;
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};
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/**
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* DOC: Slot state
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*
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* @OFF_STATE: slot is powered off, no subordinate devices are enumerated
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* @BLINKINGON_STATE: slot will be powered on after the 5 second delay,
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* Power Indicator is blinking
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* @BLINKINGOFF_STATE: slot will be powered off after the 5 second delay,
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* Power Indicator is blinking
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* @POWERON_STATE: slot is currently powering on
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* @POWEROFF_STATE: slot is currently powering off
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* @ON_STATE: slot is powered on, subordinate devices have been enumerated
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*/
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#define OFF_STATE 0
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#define BLINKINGON_STATE 1
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#define BLINKINGOFF_STATE 2
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#define POWERON_STATE 3
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#define POWEROFF_STATE 4
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#define ON_STATE 5
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/**
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* DOC: Flags to request an action from the IRQ thread
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*
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* These are stored together with events read from the Slot Status register,
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* hence must be greater than its 16-bit width.
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*
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* %DISABLE_SLOT: Disable the slot in response to a user request via sysfs or
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* an Attention Button press after the 5 second delay
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* %RERUN_ISR: Used by the IRQ handler to inform the IRQ thread that the
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* hotplug port was inaccessible when the interrupt occurred, requiring
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* that the IRQ handler is rerun by the IRQ thread after it has made the
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* hotplug port accessible by runtime resuming its parents to D0
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*/
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#define DISABLE_SLOT (1 << 16)
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#define RERUN_ISR (1 << 17)
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#define ATTN_BUTTN(ctrl) ((ctrl)->slot_cap & PCI_EXP_SLTCAP_ABP)
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#define POWER_CTRL(ctrl) ((ctrl)->slot_cap & PCI_EXP_SLTCAP_PCP)
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#define MRL_SENS(ctrl) ((ctrl)->slot_cap & PCI_EXP_SLTCAP_MRLSP)
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#define ATTN_LED(ctrl) ((ctrl)->slot_cap & PCI_EXP_SLTCAP_AIP)
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#define PWR_LED(ctrl) ((ctrl)->slot_cap & PCI_EXP_SLTCAP_PIP)
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#define HP_SUPR_RM(ctrl) ((ctrl)->slot_cap & PCI_EXP_SLTCAP_HPS)
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#define EMI(ctrl) ((ctrl)->slot_cap & PCI_EXP_SLTCAP_EIP)
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#define NO_CMD_CMPL(ctrl) ((ctrl)->slot_cap & PCI_EXP_SLTCAP_NCCS)
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#define PSN(ctrl) (((ctrl)->slot_cap & PCI_EXP_SLTCAP_PSN) >> 19)
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void pciehp_request(struct controller *ctrl, int action);
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void pciehp_handle_button_press(struct controller *ctrl);
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void pciehp_handle_disable_request(struct controller *ctrl);
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void pciehp_handle_presence_or_link_change(struct controller *ctrl, u32 events);
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int pciehp_configure_device(struct controller *ctrl);
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void pciehp_unconfigure_device(struct controller *ctrl, bool presence);
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void pciehp_queue_pushbutton_work(struct work_struct *work);
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struct controller *pcie_init(struct pcie_device *dev);
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int pcie_init_notification(struct controller *ctrl);
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void pcie_shutdown_notification(struct controller *ctrl);
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void pcie_clear_hotplug_events(struct controller *ctrl);
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void pcie_enable_interrupt(struct controller *ctrl);
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void pcie_disable_interrupt(struct controller *ctrl);
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int pciehp_power_on_slot(struct controller *ctrl);
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void pciehp_power_off_slot(struct controller *ctrl);
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void pciehp_get_power_status(struct controller *ctrl, u8 *status);
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#define INDICATOR_NOOP -1 /* Leave indicator unchanged */
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void pciehp_set_indicators(struct controller *ctrl, int pwr, int attn);
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void pciehp_get_latch_status(struct controller *ctrl, u8 *status);
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int pciehp_query_power_fault(struct controller *ctrl);
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int pciehp_card_present(struct controller *ctrl);
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int pciehp_card_present_or_link_active(struct controller *ctrl);
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int pciehp_check_link_status(struct controller *ctrl);
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int pciehp_check_link_active(struct controller *ctrl);
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void pciehp_release_ctrl(struct controller *ctrl);
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int pciehp_sysfs_enable_slot(struct hotplug_slot *hotplug_slot);
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int pciehp_sysfs_disable_slot(struct hotplug_slot *hotplug_slot);
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int pciehp_reset_slot(struct hotplug_slot *hotplug_slot, int probe);
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int pciehp_get_attention_status(struct hotplug_slot *hotplug_slot, u8 *status);
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int pciehp_set_raw_indicator_status(struct hotplug_slot *h_slot, u8 status);
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int pciehp_get_raw_indicator_status(struct hotplug_slot *h_slot, u8 *status);
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static inline const char *slot_name(struct controller *ctrl)
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{
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return hotplug_slot_name(&ctrl->hotplug_slot);
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}
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static inline struct controller *to_ctrl(struct hotplug_slot *hotplug_slot)
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{
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return container_of(hotplug_slot, struct controller, hotplug_slot);
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}
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#endif /* _PCIEHP_H */
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