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linux-next/drivers/pci/hotplug/pciehp.h
Lukas Wunner 80696f9914 PCI: pciehp: Tolerate Presence Detect hardwired to zero 
The WiGig Bus Extension (WBE) specification allows tunneling PCIe over
IEEE 802.11.  A product implementing this spec is the wil6210 from
Wilocity (now part of Qualcomm Atheros).  It integrates a PCIe switch
with a wireless network adapter:

  00.0-+              [1ae9:0101]  Upstream Port
       +-00.0-+       [1ae9:0200]  Downstream Port
       |      +-00.0  [168c:0034]  Atheros AR9462 Wireless Network Adapter
       +-02.0         [1ae9:0201]  Downstream Port
       +-03.0         [1ae9:0201]  Downstream Port

Wirelessly attached devices presumably appear below the hotplug ports
with device ID [1ae9:0201].  Oddly, the Downstream Port [1ae9:0200]
leading to the wireless network adapter is likewise Hotplug Capable,
but has its Presence Detect State bit hardwired to zero.  Even if the
Link Active bit is set, Presence Detect is zero, so this cannot be
caused by in-band presence detection but only by broken hardware.

pciehp assumes an empty slot if Presence Detect State is zero,
regardless of Link Active being one.  Consequently, up until v4.18 it
removes the wireless network adapter in pciehp_resume().  From v4.19 it
already does so in pciehp_probe().

Be lenient towards broken hardware and assume the slot is occupied if
Link Active is set:  Introduce pciehp_card_present_or_link_active()
and use it in lieu of pciehp_get_adapter_status() everywhere, except
in pciehp_handle_presence_or_link_change() whose log messages depend
on which of Presence Detect State or Link Active is set.

Remove the Presence Detect State check from __pciehp_enable_slot()
because it is only called if either of Presence Detect State or Link
Active is set.

Caution: There is a possibility that broken hardware exists which has
working Presence Detect but hardwires Link Active to one.  On such
hardware the slot will now incorrectly be considered always occupied.
If such hardware is discovered, this commit can be rolled back and a
quirk can be added which sets is_hotplug_bridge = 0 for [1ae9:0200].

Link: https://bugzilla.kernel.org/show_bug.cgi?id=200839
Reported-and-tested-by: David Yang <mmyangfl@gmail.com>
Signed-off-by: Lukas Wunner <lukas@wunner.de>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Cc: Rajat Jain <rajatja@google.com>
Cc: Ashok Raj <ashok.raj@intel.com>
2018-09-18 17:52:15 -05:00

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/* SPDX-License-Identifier: GPL-2.0+ */
/*
* PCI Express Hot Plug Controller Driver
*
* Copyright (C) 1995,2001 Compaq Computer Corporation
* Copyright (C) 2001 Greg Kroah-Hartman (greg@kroah.com)
* Copyright (C) 2001 IBM Corp.
* Copyright (C) 2003-2004 Intel Corporation
*
* All rights reserved.
*
* Send feedback to <greg@kroah.com>, <kristen.c.accardi@intel.com>
*
*/
#ifndef _PCIEHP_H
#define _PCIEHP_H
#include <linux/types.h>
#include <linux/pci.h>
#include <linux/pci_hotplug.h>
#include <linux/delay.h>
#include <linux/mutex.h>
#include <linux/rwsem.h>
#include <linux/workqueue.h>
#include "../pcie/portdrv.h"
#define MY_NAME "pciehp"
extern bool pciehp_poll_mode;
extern int pciehp_poll_time;
extern bool pciehp_debug;
#define dbg(format, arg...) \
do { \
if (pciehp_debug) \
printk(KERN_DEBUG "%s: " format, MY_NAME, ## arg); \
} while (0)
#define err(format, arg...) \
printk(KERN_ERR "%s: " format, MY_NAME, ## arg)
#define info(format, arg...) \
printk(KERN_INFO "%s: " format, MY_NAME, ## arg)
#define warn(format, arg...) \
printk(KERN_WARNING "%s: " format, MY_NAME, ## arg)
#define ctrl_dbg(ctrl, format, arg...) \
do { \
if (pciehp_debug) \
dev_printk(KERN_DEBUG, &ctrl->pcie->device, \
format, ## arg); \
} while (0)
#define ctrl_err(ctrl, format, arg...) \
dev_err(&ctrl->pcie->device, format, ## arg)
#define ctrl_info(ctrl, format, arg...) \
dev_info(&ctrl->pcie->device, format, ## arg)
#define ctrl_warn(ctrl, format, arg...) \
dev_warn(&ctrl->pcie->device, format, ## arg)
#define SLOT_NAME_SIZE 10
/**
* struct slot - PCIe hotplug slot
* @state: current state machine position
* @ctrl: pointer to the slot's controller structure
* @hotplug_slot: pointer to the structure registered with the PCI hotplug core
* @work: work item to turn the slot on or off after 5 seconds in response to
* an Attention Button press
* @lock: protects reads and writes of @state;
* protects scheduling, execution and cancellation of @work
*/
struct slot {
u8 state;
struct controller *ctrl;
struct hotplug_slot *hotplug_slot;
struct delayed_work work;
struct mutex lock;
};
/**
* struct controller - PCIe hotplug controller
* @ctrl_lock: serializes writes to the Slot Control register
* @pcie: pointer to the controller's PCIe port service device
* @reset_lock: prevents access to the Data Link Layer Link Active bit in the
* Link Status register and to the Presence Detect State bit in the Slot
* Status register during a slot reset which may cause them to flap
* @slot: pointer to the controller's slot structure
* @queue: wait queue to wake up on reception of a Command Completed event,
* used for synchronous writes to the Slot Control register
* @slot_cap: cached copy of the Slot Capabilities register
* @slot_ctrl: cached copy of the Slot Control register
* @poll_thread: thread to poll for slot events if no IRQ is available,
* enabled with pciehp_poll_mode module parameter
* @cmd_started: jiffies when the Slot Control register was last written;
* the next write is allowed 1 second later, absent a Command Completed
* interrupt (PCIe r4.0, sec 6.7.3.2)
* @cmd_busy: flag set on Slot Control register write, cleared by IRQ handler
* on reception of a Command Completed event
* @link_active_reporting: cached copy of Data Link Layer Link Active Reporting
* Capable bit in Link Capabilities register; if this bit is zero, the
* Data Link Layer Link Active bit in the Link Status register will never
* be set and the driver is thus confined to wait 1 second before assuming
* the link to a hotplugged device is up and accessing it
* @notification_enabled: whether the IRQ was requested successfully
* @power_fault_detected: whether a power fault was detected by the hardware
* that has not yet been cleared by the user
* @pending_events: used by the IRQ handler to save events retrieved from the
* Slot Status register for later consumption by the IRQ thread
* @request_result: result of last user request submitted to the IRQ thread
* @requester: wait queue to wake up on completion of user request,
* used for synchronous slot enable/disable request via sysfs
*/
struct controller {
struct mutex ctrl_lock;
struct pcie_device *pcie;
struct rw_semaphore reset_lock;
struct slot *slot;
wait_queue_head_t queue;
u32 slot_cap;
u16 slot_ctrl;
struct task_struct *poll_thread;
unsigned long cmd_started; /* jiffies */
unsigned int cmd_busy:1;
unsigned int link_active_reporting:1;
unsigned int notification_enabled:1;
unsigned int power_fault_detected;
atomic_t pending_events;
int request_result;
wait_queue_head_t requester;
};
/**
* DOC: Slot state
*
* @OFF_STATE: slot is powered off, no subordinate devices are enumerated
* @BLINKINGON_STATE: slot will be powered on after the 5 second delay,
* green led is blinking
* @BLINKINGOFF_STATE: slot will be powered off after the 5 second delay,
* green led is blinking
* @POWERON_STATE: slot is currently powering on
* @POWEROFF_STATE: slot is currently powering off
* @ON_STATE: slot is powered on, subordinate devices have been enumerated
*/
#define OFF_STATE 0
#define BLINKINGON_STATE 1
#define BLINKINGOFF_STATE 2
#define POWERON_STATE 3
#define POWEROFF_STATE 4
#define ON_STATE 5
/**
* DOC: Flags to request an action from the IRQ thread
*
* These are stored together with events read from the Slot Status register,
* hence must be greater than its 16-bit width.
*
* %DISABLE_SLOT: Disable the slot in response to a user request via sysfs or
* an Attention Button press after the 5 second delay
* %RERUN_ISR: Used by the IRQ handler to inform the IRQ thread that the
* hotplug port was inaccessible when the interrupt occurred, requiring
* that the IRQ handler is rerun by the IRQ thread after it has made the
* hotplug port accessible by runtime resuming its parents to D0
*/
#define DISABLE_SLOT (1 << 16)
#define RERUN_ISR (1 << 17)
#define ATTN_BUTTN(ctrl) ((ctrl)->slot_cap & PCI_EXP_SLTCAP_ABP)
#define POWER_CTRL(ctrl) ((ctrl)->slot_cap & PCI_EXP_SLTCAP_PCP)
#define MRL_SENS(ctrl) ((ctrl)->slot_cap & PCI_EXP_SLTCAP_MRLSP)
#define ATTN_LED(ctrl) ((ctrl)->slot_cap & PCI_EXP_SLTCAP_AIP)
#define PWR_LED(ctrl) ((ctrl)->slot_cap & PCI_EXP_SLTCAP_PIP)
#define HP_SUPR_RM(ctrl) ((ctrl)->slot_cap & PCI_EXP_SLTCAP_HPS)
#define EMI(ctrl) ((ctrl)->slot_cap & PCI_EXP_SLTCAP_EIP)
#define NO_CMD_CMPL(ctrl) ((ctrl)->slot_cap & PCI_EXP_SLTCAP_NCCS)
#define PSN(ctrl) (((ctrl)->slot_cap & PCI_EXP_SLTCAP_PSN) >> 19)
void pciehp_request(struct controller *ctrl, int action);
void pciehp_handle_button_press(struct slot *slot);
void pciehp_handle_disable_request(struct slot *slot);
void pciehp_handle_presence_or_link_change(struct slot *slot, u32 events);
int pciehp_configure_device(struct slot *p_slot);
void pciehp_unconfigure_device(struct slot *p_slot, bool presence);
void pciehp_queue_pushbutton_work(struct work_struct *work);
struct controller *pcie_init(struct pcie_device *dev);
int pcie_init_notification(struct controller *ctrl);
void pcie_shutdown_notification(struct controller *ctrl);
void pcie_clear_hotplug_events(struct controller *ctrl);
int pciehp_power_on_slot(struct slot *slot);
void pciehp_power_off_slot(struct slot *slot);
void pciehp_get_power_status(struct slot *slot, u8 *status);
void pciehp_set_attention_status(struct slot *slot, u8 status);
void pciehp_get_latch_status(struct slot *slot, u8 *status);
int pciehp_query_power_fault(struct slot *slot);
void pciehp_green_led_on(struct slot *slot);
void pciehp_green_led_off(struct slot *slot);
void pciehp_green_led_blink(struct slot *slot);
bool pciehp_card_present(struct controller *ctrl);
bool pciehp_card_present_or_link_active(struct controller *ctrl);
int pciehp_check_link_status(struct controller *ctrl);
bool pciehp_check_link_active(struct controller *ctrl);
void pciehp_release_ctrl(struct controller *ctrl);
int pciehp_sysfs_enable_slot(struct hotplug_slot *hotplug_slot);
int pciehp_sysfs_disable_slot(struct hotplug_slot *hotplug_slot);
int pciehp_reset_slot(struct hotplug_slot *hotplug_slot, int probe);
int pciehp_get_attention_status(struct hotplug_slot *hotplug_slot, u8 *status);
int pciehp_set_raw_indicator_status(struct hotplug_slot *h_slot, u8 status);
int pciehp_get_raw_indicator_status(struct hotplug_slot *h_slot, u8 *status);
static inline const char *slot_name(struct slot *slot)
{
return hotplug_slot_name(slot->hotplug_slot);
}
#endif /* _PCIEHP_H */
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