// SPDX-License-Identifier: GPL-2.0+
/*
 * PCI Express PCI Hot Plug 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>
 */

#define dev_fmt(fmt) "pciehp: " fmt

#include <linux/bitfield.h>
#include <linux/dmi.h>
#include <linux/kernel.h>
#include <linux/types.h>
#include <linux/jiffies.h>
#include <linux/kthread.h>
#include <linux/pci.h>
#include <linux/pm_runtime.h>
#include <linux/interrupt.h>
#include <linux/slab.h>

#include "../pci.h"
#include "pciehp.h"

static const struct dmi_system_id inband_presence_disabled_dmi_table[] = {
        /*
         * Match all Dell systems, as some Dell systems have inband
         * presence disabled on NVMe slots (but don't support the bit to
         * report it). Setting inband presence disabled should have no
         * negative effect, except on broken hotplug slots that never
         * assert presence detect--and those will still work, they will
         * just have a bit of extra delay before being probed.
         */
        {
                .ident = "Dell System",
                .matches = {
                        DMI_MATCH(DMI_OEM_STRING, "Dell System"),
                },
        },
        {}
};

static inline struct pci_dev *ctrl_dev(struct controller *ctrl)
{
        return ctrl->pcie->port;
}

static irqreturn_t pciehp_isr(int irq, void *dev_id);
static irqreturn_t pciehp_ist(int irq, void *dev_id);
static int pciehp_poll(void *data);

static inline int pciehp_request_irq(struct controller *ctrl)
{
        int retval, irq = ctrl->pcie->irq;

        if (pciehp_poll_mode) {
                ctrl->poll_thread = kthread_run(&pciehp_poll, ctrl,
                                                "pciehp_poll-%s",
                                                slot_name(ctrl));
                return PTR_ERR_OR_ZERO(ctrl->poll_thread);
        }

        /* Installs the interrupt handler */
        retval = request_threaded_irq(irq, pciehp_isr, pciehp_ist,
                                      IRQF_SHARED, "pciehp", ctrl);
        if (retval)
                ctrl_err(ctrl, "Cannot get irq %d for the hotplug controller\n",
                         irq);
        return retval;
}

static inline void pciehp_free_irq(struct controller *ctrl)
{
        if (pciehp_poll_mode)
                kthread_stop(ctrl->poll_thread);
        else
                free_irq(ctrl->pcie->irq, ctrl);
}

static int pcie_poll_cmd(struct controller *ctrl, int timeout)
{
        struct pci_dev *pdev = ctrl_dev(ctrl);
        u16 slot_status;

        do {
                pcie_capability_read_word(pdev, PCI_EXP_SLTSTA, &slot_status);
                if (PCI_POSSIBLE_ERROR(slot_status)) {
                        ctrl_info(ctrl, "%s: no response from device\n",
                                  __func__);
                        return 0;
                }

                if (slot_status & PCI_EXP_SLTSTA_CC) {
                        pcie_capability_write_word(pdev, PCI_EXP_SLTSTA,
                                                   PCI_EXP_SLTSTA_CC);
                        ctrl->cmd_busy = 0;
                        smp_mb();
                        return 1;
                }
                msleep(10);
                timeout -= 10;
        } while (timeout >= 0);
        return 0;       /* timeout */
}

static void pcie_wait_cmd(struct controller *ctrl)
{
        unsigned int msecs = pciehp_poll_mode ? 2500 : 1000;
        unsigned long duration = msecs_to_jiffies(msecs);
        unsigned long cmd_timeout = ctrl->cmd_started + duration;
        unsigned long now, timeout;
        int rc;

        /*
         * If the controller does not generate notifications for command
         * completions, we never need to wait between writes.
         */
        if (NO_CMD_CMPL(ctrl))
                return;

        if (!ctrl->cmd_busy)
                return;

        /*
         * Even if the command has already timed out, we want to call
         * pcie_poll_cmd() so it can clear PCI_EXP_SLTSTA_CC.
         */
        now = jiffies;
        if (time_before_eq(cmd_timeout, now))
                timeout = 1;
        else
                timeout = cmd_timeout - now;

        if (ctrl->slot_ctrl & PCI_EXP_SLTCTL_HPIE &&
            ctrl->slot_ctrl & PCI_EXP_SLTCTL_CCIE)
                rc = wait_event_timeout(ctrl->queue, !ctrl->cmd_busy, timeout);
        else
                rc = pcie_poll_cmd(ctrl, jiffies_to_msecs(timeout));

        if (!rc)
                ctrl_info(ctrl, "Timeout on hotplug command %#06x (issued %u msec ago)\n",
                          ctrl->slot_ctrl,
                          jiffies_to_msecs(jiffies - ctrl->cmd_started));
}

#define CC_ERRATUM_MASK         (PCI_EXP_SLTCTL_PCC |   \
                                 PCI_EXP_SLTCTL_PIC |   \
                                 PCI_EXP_SLTCTL_AIC |   \
                                 PCI_EXP_SLTCTL_EIC)

static void pcie_do_write_cmd(struct controller *ctrl, u16 cmd,
                              u16 mask, bool wait)
{
        struct pci_dev *pdev = ctrl_dev(ctrl);
        u16 slot_ctrl_orig, slot_ctrl;

        mutex_lock(&ctrl->ctrl_lock);

        /*
         * Always wait for any previous command that might still be in progress
         */
        pcie_wait_cmd(ctrl);

        pcie_capability_read_word(pdev, PCI_EXP_SLTCTL, &slot_ctrl);
        if (PCI_POSSIBLE_ERROR(slot_ctrl)) {
                ctrl_info(ctrl, "%s: no response from device\n", __func__);
                goto out;
        }

        slot_ctrl_orig = slot_ctrl;
        slot_ctrl &= ~mask;
        slot_ctrl |= (cmd & mask);
        ctrl->cmd_busy = 1;
        smp_mb();
        ctrl->slot_ctrl = slot_ctrl;
        pcie_capability_write_word(pdev, PCI_EXP_SLTCTL, slot_ctrl);
        ctrl->cmd_started = jiffies;

        /*
         * Controllers with the Intel CF118 and similar errata advertise
         * Command Completed support, but they only set Command Completed
         * if we change the "Control" bits for power, power indicator,
         * attention indicator, or interlock.  If we only change the
         * "Enable" bits, they never set the Command Completed bit.
         */
        if (pdev->broken_cmd_compl &&
            (slot_ctrl_orig & CC_ERRATUM_MASK) == (slot_ctrl & CC_ERRATUM_MASK))
                ctrl->cmd_busy = 0;

        /*
         * Optionally wait for the hardware to be ready for a new command,
         * indicating completion of the above issued command.
         */
        if (wait)
                pcie_wait_cmd(ctrl);

out:
        mutex_unlock(&ctrl->ctrl_lock);
}

/**
 * pcie_write_cmd - Issue controller command
 * @ctrl: controller to which the command is issued
 * @cmd:  command value written to slot control register
 * @mask: bitmask of slot control register to be modified
 */
static void pcie_write_cmd(struct controller *ctrl, u16 cmd, u16 mask)
{
        pcie_do_write_cmd(ctrl, cmd, mask, true);
}

/* Same as above without waiting for the hardware to latch */
static void pcie_write_cmd_nowait(struct controller *ctrl, u16 cmd, u16 mask)
{
        pcie_do_write_cmd(ctrl, cmd, mask, false);
}

/**
 * pciehp_check_link_active() - Is the link active
 * @ctrl: PCIe hotplug controller
 *
 * Check whether the downstream link is currently active. Note it is
 * possible that the card is removed immediately after this so the
 * caller may need to take it into account.
 *
 * If the hotplug controller itself is not available anymore returns
 * %-ENODEV.
 */
int pciehp_check_link_active(struct controller *ctrl)
{
        struct pci_dev *pdev = ctrl_dev(ctrl);
        u16 lnk_status;
        int ret;

        ret = pcie_capability_read_word(pdev, PCI_EXP_LNKSTA, &lnk_status);
        if (ret == PCIBIOS_DEVICE_NOT_FOUND || PCI_POSSIBLE_ERROR(lnk_status))
                return -ENODEV;

        ret = !!(lnk_status & PCI_EXP_LNKSTA_DLLLA);
        ctrl_dbg(ctrl, "%s: lnk_status = %x\n", __func__, lnk_status);

        return ret;
}

static bool pci_bus_check_dev(struct pci_bus *bus, int devfn)
{
        u32 l;
        int count = 0;
        int delay = 1000, step = 20;
        bool found = false;

        do {
                found = pci_bus_read_dev_vendor_id(bus, devfn, &l, 0);
                count++;

                if (found)
                        break;

                msleep(step);
                delay -= step;
        } while (delay > 0);

        if (count > 1)
                pr_debug("pci %04x:%02x:%02x.%d id reading try %d times with interval %d ms to get %08x\n",
                        pci_domain_nr(bus), bus->number, PCI_SLOT(devfn),
                        PCI_FUNC(devfn), count, step, l);

        return found;
}

static void pcie_wait_for_presence(struct pci_dev *pdev)
{
        int timeout = 1250;
        u16 slot_status;

        do {
                pcie_capability_read_word(pdev, PCI_EXP_SLTSTA, &slot_status);
                if (slot_status & PCI_EXP_SLTSTA_PDS)
                        return;
                msleep(10);
                timeout -= 10;
        } while (timeout > 0);
}

int pciehp_check_link_status(struct controller *ctrl)
{
        struct pci_dev *pdev = ctrl_dev(ctrl);
        bool found;
        u16 lnk_status, linksta2;

        if (!pcie_wait_for_link(pdev, true)) {
                ctrl_info(ctrl, "Slot(%s): No link\n", slot_name(ctrl));
                return -1;
        }

        if (ctrl->inband_presence_disabled)
                pcie_wait_for_presence(pdev);

        found = pci_bus_check_dev(ctrl->pcie->port->subordinate,
                                        PCI_DEVFN(0, 0));

        /* ignore link or presence changes up to this point */
        if (found)
                atomic_and(~(PCI_EXP_SLTSTA_DLLSC | PCI_EXP_SLTSTA_PDC),
                           &ctrl->pending_events);

        pcie_capability_read_word(pdev, PCI_EXP_LNKSTA, &lnk_status);
        ctrl_dbg(ctrl, "%s: lnk_status = %x\n", __func__, lnk_status);
        if ((lnk_status & PCI_EXP_LNKSTA_LT) ||
            !(lnk_status & PCI_EXP_LNKSTA_NLW)) {
                ctrl_info(ctrl, "Slot(%s): Cannot train link: status %#06x\n",
                          slot_name(ctrl), lnk_status);
                return -1;
        }

        pcie_capability_read_word(pdev, PCI_EXP_LNKSTA2, &linksta2);
        __pcie_update_link_speed(ctrl->pcie->port->subordinate, PCIE_HOTPLUG,
                                 lnk_status, linksta2);

        if (!found) {
                ctrl_info(ctrl, "Slot(%s): No device found\n",
                          slot_name(ctrl));
                return -1;
        }

        return 0;
}

static int __pciehp_link_set(struct controller *ctrl, bool enable)
{
        struct pci_dev *pdev = ctrl_dev(ctrl);

        pcie_capability_clear_and_set_word(pdev, PCI_EXP_LNKCTL,
                                           PCI_EXP_LNKCTL_LD,
                                           enable ? 0 : PCI_EXP_LNKCTL_LD);

        return 0;
}

static int pciehp_link_enable(struct controller *ctrl)
{
        return __pciehp_link_set(ctrl, true);
}

int pciehp_get_raw_indicator_status(struct hotplug_slot *hotplug_slot,
                                    u8 *status)
{
        struct controller *ctrl = to_ctrl(hotplug_slot);
        struct pci_dev *pdev = ctrl_dev(ctrl);
        u16 slot_ctrl;

        pci_config_pm_runtime_get(pdev);
        pcie_capability_read_word(pdev, PCI_EXP_SLTCTL, &slot_ctrl);
        pci_config_pm_runtime_put(pdev);
        *status = (slot_ctrl & (PCI_EXP_SLTCTL_AIC | PCI_EXP_SLTCTL_PIC)) >> 6;
        return 0;
}

int pciehp_get_attention_status(struct hotplug_slot *hotplug_slot, u8 *status)
{
        struct controller *ctrl = to_ctrl(hotplug_slot);
        struct pci_dev *pdev = ctrl_dev(ctrl);
        u16 slot_ctrl;

        pci_config_pm_runtime_get(pdev);
        pcie_capability_read_word(pdev, PCI_EXP_SLTCTL, &slot_ctrl);
        pci_config_pm_runtime_put(pdev);
        ctrl_dbg(ctrl, "%s: SLOTCTRL %x, value read %x\n", __func__,
                 pci_pcie_cap(ctrl->pcie->port) + PCI_EXP_SLTCTL, slot_ctrl);

        switch (slot_ctrl & PCI_EXP_SLTCTL_AIC) {
        case PCI_EXP_SLTCTL_ATTN_IND_ON:
                *status = 1;    /* On */
                break;
        case PCI_EXP_SLTCTL_ATTN_IND_BLINK:
                *status = 2;    /* Blink */
                break;
        case PCI_EXP_SLTCTL_ATTN_IND_OFF:
                *status = 0;    /* Off */
                break;
        default:
                *status = 0xFF;
                break;
        }

        return 0;
}

void pciehp_get_power_status(struct controller *ctrl, u8 *status)
{
        struct pci_dev *pdev = ctrl_dev(ctrl);
        u16 slot_ctrl;

        pcie_capability_read_word(pdev, PCI_EXP_SLTCTL, &slot_ctrl);
        ctrl_dbg(ctrl, "%s: SLOTCTRL %x value read %x\n", __func__,
                 pci_pcie_cap(ctrl->pcie->port) + PCI_EXP_SLTCTL, slot_ctrl);

        switch (slot_ctrl & PCI_EXP_SLTCTL_PCC) {
        case PCI_EXP_SLTCTL_PWR_ON:
                *status = 1;    /* On */
                break;
        case PCI_EXP_SLTCTL_PWR_OFF:
                *status = 0;    /* Off */
                break;
        default:
                *status = 0xFF;
                break;
        }
}

void pciehp_get_latch_status(struct controller *ctrl, u8 *status)
{
        struct pci_dev *pdev = ctrl_dev(ctrl);
        u16 slot_status;

        pcie_capability_read_word(pdev, PCI_EXP_SLTSTA, &slot_status);
        *status = !!(slot_status & PCI_EXP_SLTSTA_MRLSS);
}

/**
 * pciehp_card_present() - Is the card present
 * @ctrl: PCIe hotplug controller
 *
 * Function checks whether the card is currently present in the slot and
 * in that case returns true. Note it is possible that the card is
 * removed immediately after the check so the caller may need to take
 * this into account.
 *
 * If the hotplug controller itself is not available anymore returns
 * %-ENODEV.
 */
int pciehp_card_present(struct controller *ctrl)
{
        struct pci_dev *pdev = ctrl_dev(ctrl);
        u16 slot_status;
        int ret;

        ret = pcie_capability_read_word(pdev, PCI_EXP_SLTSTA, &slot_status);
        if (ret == PCIBIOS_DEVICE_NOT_FOUND || PCI_POSSIBLE_ERROR(slot_status))
                return -ENODEV;

        return !!(slot_status & PCI_EXP_SLTSTA_PDS);
}

/**
 * pciehp_card_present_or_link_active() - whether given slot is occupied
 * @ctrl: PCIe hotplug controller
 *
 * Unlike pciehp_card_present(), which determines presence solely from the
 * Presence Detect State bit, this helper also returns true if the Link Active
 * bit is set.  This is a concession to broken hotplug ports which hardwire
 * Presence Detect State to zero, such as Wilocity's [1ae9:0200].
 *
 * Returns: %1 if the slot is occupied and %0 if it is not. If the hotplug
 *          port is not present anymore returns %-ENODEV.
 */
int pciehp_card_present_or_link_active(struct controller *ctrl)
{
        int ret;

        ret = pciehp_card_present(ctrl);
        if (ret)
                return ret;

        return pciehp_check_link_active(ctrl);
}

int pciehp_query_power_fault(struct controller *ctrl)
{
        struct pci_dev *pdev = ctrl_dev(ctrl);
        u16 slot_status;

        pcie_capability_read_word(pdev, PCI_EXP_SLTSTA, &slot_status);
        return !!(slot_status & PCI_EXP_SLTSTA_PFD);
}

int pciehp_set_raw_indicator_status(struct hotplug_slot *hotplug_slot,
                                    u8 status)
{
        struct controller *ctrl = to_ctrl(hotplug_slot);
        struct pci_dev *pdev = ctrl_dev(ctrl);

        pci_config_pm_runtime_get(pdev);

        /* Attention and Power Indicator Control bits are supported */
        pcie_write_cmd_nowait(ctrl, FIELD_PREP(PCI_EXP_SLTCTL_AIC | PCI_EXP_SLTCTL_PIC, status),
                              PCI_EXP_SLTCTL_AIC | PCI_EXP_SLTCTL_PIC);
        pci_config_pm_runtime_put(pdev);
        return 0;
}

/**
 * pciehp_set_indicators() - set attention indicator, power indicator, or both
 * @ctrl: PCIe hotplug controller
 * @pwr: one of:
 *      PCI_EXP_SLTCTL_PWR_IND_ON
 *      PCI_EXP_SLTCTL_PWR_IND_BLINK
 *      PCI_EXP_SLTCTL_PWR_IND_OFF
 * @attn: one of:
 *      PCI_EXP_SLTCTL_ATTN_IND_ON
 *      PCI_EXP_SLTCTL_ATTN_IND_BLINK
 *      PCI_EXP_SLTCTL_ATTN_IND_OFF
 *
 * Either @pwr or @attn can also be INDICATOR_NOOP to leave that indicator
 * unchanged.
 */
void pciehp_set_indicators(struct controller *ctrl, int pwr, int attn)
{
        u16 cmd = 0, mask = 0;

        if (PWR_LED(ctrl) && pwr != INDICATOR_NOOP) {
                cmd |= (pwr & PCI_EXP_SLTCTL_PIC);
                mask |= PCI_EXP_SLTCTL_PIC;
        }

        if (ATTN_LED(ctrl) && attn != INDICATOR_NOOP) {
                cmd |= (attn & PCI_EXP_SLTCTL_AIC);
                mask |= PCI_EXP_SLTCTL_AIC;
        }

        if (cmd) {
                pcie_write_cmd_nowait(ctrl, cmd, mask);
                ctrl_dbg(ctrl, "%s: SLOTCTRL %x write cmd %x\n", __func__,
                         pci_pcie_cap(ctrl->pcie->port) + PCI_EXP_SLTCTL, cmd);
        }
}

int pciehp_power_on_slot(struct controller *ctrl)
{
        struct pci_dev *pdev = ctrl_dev(ctrl);
        u16 slot_status;
        int retval;

        /* Clear power-fault bit from previous power failures */
        pcie_capability_read_word(pdev, PCI_EXP_SLTSTA, &slot_status);
        if (slot_status & PCI_EXP_SLTSTA_PFD)
                pcie_capability_write_word(pdev, PCI_EXP_SLTSTA,
                                           PCI_EXP_SLTSTA_PFD);
        ctrl->power_fault_detected = 0;

        pcie_write_cmd(ctrl, PCI_EXP_SLTCTL_PWR_ON, PCI_EXP_SLTCTL_PCC);
        ctrl_dbg(ctrl, "%s: SLOTCTRL %x write cmd %x\n", __func__,
                 pci_pcie_cap(ctrl->pcie->port) + PCI_EXP_SLTCTL,
                 PCI_EXP_SLTCTL_PWR_ON);

        retval = pciehp_link_enable(ctrl);
        if (retval)
                ctrl_err(ctrl, "%s: Can not enable the link!\n", __func__);

        return retval;
}

void pciehp_power_off_slot(struct controller *ctrl)
{
        pcie_write_cmd(ctrl, PCI_EXP_SLTCTL_PWR_OFF, PCI_EXP_SLTCTL_PCC);
        ctrl_dbg(ctrl, "%s: SLOTCTRL %x write cmd %x\n", __func__,
                 pci_pcie_cap(ctrl->pcie->port) + PCI_EXP_SLTCTL,
                 PCI_EXP_SLTCTL_PWR_OFF);
}

bool pciehp_device_replaced(struct controller *ctrl)
{
        struct pci_dev *pdev __free(pci_dev_put) = NULL;
        u32 reg;

        if (pci_dev_is_disconnected(ctrl->pcie->port))
                return false;

        pdev = pci_get_slot(ctrl->pcie->port->subordinate, PCI_DEVFN(0, 0));
        if (!pdev)
                return true;

        if (pci_read_config_dword(pdev, PCI_VENDOR_ID, &reg) ||
            reg != (pdev->vendor | (pdev->device << 16)) ||
            pci_read_config_dword(pdev, PCI_CLASS_REVISION, &reg) ||
            reg != (pdev->revision | (pdev->class << 8)))
                return true;

        if (pdev->hdr_type == PCI_HEADER_TYPE_NORMAL &&
            (pci_read_config_dword(pdev, PCI_SUBSYSTEM_VENDOR_ID, &reg) ||
             reg != (pdev->subsystem_vendor | (pdev->subsystem_device << 16))))
                return true;

        if (pci_get_dsn(pdev) != ctrl->dsn)
                return true;

        return false;
}

static void pciehp_ignore_link_change(struct controller *ctrl,
                                      struct pci_dev *pdev, int irq,
                                      u16 ignored_events)
{
        /*
         * Ignore link changes which occurred while waiting for DPC recovery.
         * Could be several if DPC triggered multiple times consecutively.
         * Also ignore link changes caused by Secondary Bus Reset, etc.
         */
        synchronize_hardirq(irq);
        atomic_and(~ignored_events, &ctrl->pending_events);
        if (pciehp_poll_mode)
                pcie_capability_write_word(pdev, PCI_EXP_SLTSTA,
                                           ignored_events);
        ctrl_info(ctrl, "Slot(%s): Link Down/Up ignored\n", slot_name(ctrl));

        /*
         * If the link is unexpectedly down after successful recovery,
         * the corresponding link change may have been ignored above.
         * Synthesize it to ensure that it is acted on.
         */
        down_read_nested(&ctrl->reset_lock, ctrl->depth);
        if (!pciehp_check_link_active(ctrl) || pciehp_device_replaced(ctrl))
                pciehp_request(ctrl, ignored_events);
        up_read(&ctrl->reset_lock);
}

static irqreturn_t pciehp_isr(int irq, void *dev_id)
{
        struct controller *ctrl = (struct controller *)dev_id;
        struct pci_dev *pdev = ctrl_dev(ctrl);
        struct device *parent = pdev->dev.parent;
        u16 status, events = 0;

        /*
         * Interrupts only occur in D3hot or shallower and only if enabled
         * in the Slot Control register (PCIe r4.0, sec 6.7.3.4).
         */
        if (pdev->current_state == PCI_D3cold ||
            (!(ctrl->slot_ctrl & PCI_EXP_SLTCTL_HPIE) && !pciehp_poll_mode))
                return IRQ_NONE;

        /*
         * Keep the port accessible by holding a runtime PM ref on its parent.
         * Defer resume of the parent to the IRQ thread if it's suspended.
         * Mask the interrupt until then.
         */
        if (parent) {
                pm_runtime_get_noresume(parent);
                if (!pm_runtime_active(parent)) {
                        pm_runtime_put(parent);
                        disable_irq_nosync(irq);
                        atomic_or(RERUN_ISR, &ctrl->pending_events);
                        return IRQ_WAKE_THREAD;
                }
        }

read_status:
        pcie_capability_read_word(pdev, PCI_EXP_SLTSTA, &status);
        if (PCI_POSSIBLE_ERROR(status)) {
                ctrl_info(ctrl, "%s: no response from device\n", __func__);
                if (parent)
                        pm_runtime_put(parent);
                return IRQ_NONE;
        }

        /*
         * Slot Status contains plain status bits as well as event
         * notification bits; right now we only want the event bits.
         */
        status &= PCI_EXP_SLTSTA_ABP | PCI_EXP_SLTSTA_PFD |
                  PCI_EXP_SLTSTA_PDC | PCI_EXP_SLTSTA_CC |
                  PCI_EXP_SLTSTA_DLLSC;

        /*
         * If we've already reported a power fault, don't report it again
         * until we've done something to handle it.
         */
        if (ctrl->power_fault_detected)
                status &= ~PCI_EXP_SLTSTA_PFD;
        else if (status & PCI_EXP_SLTSTA_PFD)
                ctrl->power_fault_detected = true;

        events |= status;
        if (!events) {
                if (parent)
                        pm_runtime_put(parent);
                return IRQ_NONE;
        }

        if (status) {
                pcie_capability_write_word(pdev, PCI_EXP_SLTSTA, status);

                /*
                 * In MSI mode, all event bits must be zero before the port
                 * will send a new interrupt (PCIe Base Spec r5.0 sec 6.7.3.4).
                 * So re-read the Slot Status register in case a bit was set
                 * between read and write.
                 */
                if (pci_dev_msi_enabled(pdev) && !pciehp_poll_mode)
                        goto read_status;
        }

        ctrl_dbg(ctrl, "pending interrupts %#06x from Slot Status\n", events);
        if (parent)
                pm_runtime_put(parent);

        /*
         * Command Completed notifications are not deferred to the
         * IRQ thread because it may be waiting for their arrival.
         */
        if (events & PCI_EXP_SLTSTA_CC) {
                ctrl->cmd_busy = 0;
                smp_mb();
                wake_up(&ctrl->queue);

                if (events == PCI_EXP_SLTSTA_CC)
                        return IRQ_HANDLED;

                events &= ~PCI_EXP_SLTSTA_CC;
        }

        if (pdev->ignore_hotplug) {
                ctrl_dbg(ctrl, "ignoring hotplug event %#06x\n", events);
                return IRQ_HANDLED;
        }

        /* Save pending events for consumption by IRQ thread. */
        atomic_or(events, &ctrl->pending_events);
        return IRQ_WAKE_THREAD;
}

static irqreturn_t pciehp_ist(int irq, void *dev_id)
{
        struct controller *ctrl = (struct controller *)dev_id;
        struct pci_dev *pdev = ctrl_dev(ctrl);
        irqreturn_t ret;
        u32 events;

        ctrl->ist_running = true;
        pci_config_pm_runtime_get(pdev);

        /* rerun pciehp_isr() if the port was inaccessible on interrupt */
        if (atomic_fetch_and(~RERUN_ISR, &ctrl->pending_events) & RERUN_ISR) {
                ret = pciehp_isr(irq, dev_id);
                enable_irq(irq);
                if (ret != IRQ_WAKE_THREAD)
                        goto out;
        }

        synchronize_hardirq(irq);
        events = atomic_xchg(&ctrl->pending_events, 0);
        if (!events) {
                ret = IRQ_NONE;
                goto out;
        }

        /* Check Attention Button Pressed */
        if (events & PCI_EXP_SLTSTA_ABP)
                pciehp_handle_button_press(ctrl);

        /* Check Power Fault Detected */
        if (events & PCI_EXP_SLTSTA_PFD) {
                ctrl_err(ctrl, "Slot(%s): Power fault\n", slot_name(ctrl));
                pciehp_set_indicators(ctrl, PCI_EXP_SLTCTL_PWR_IND_OFF,
                                      PCI_EXP_SLTCTL_ATTN_IND_ON);
        }

        /*
         * Ignore Link Down/Up events caused by Downstream Port Containment
         * if recovery succeeded, or caused by Secondary Bus Reset,
         * suspend to D3cold, firmware update, FPGA reconfiguration, etc.
         */
        if ((events & (PCI_EXP_SLTSTA_PDC | PCI_EXP_SLTSTA_DLLSC)) &&
            (pci_dpc_recovered(pdev) || pci_hp_spurious_link_change(pdev)) &&
            ctrl->state == ON_STATE) {
                u16 ignored_events = PCI_EXP_SLTSTA_DLLSC;

                if (!ctrl->inband_presence_disabled)
                        ignored_events |= PCI_EXP_SLTSTA_PDC;

                events &= ~ignored_events;
                pciehp_ignore_link_change(ctrl, pdev, irq, ignored_events);
        }

        /*
         * Disable requests have higher priority than Presence Detect Changed
         * or Data Link Layer State Changed events.
         */
        down_read_nested(&ctrl->reset_lock, ctrl->depth);
        if (events & DISABLE_SLOT)
                pciehp_handle_disable_request(ctrl);
        else if (events & (PCI_EXP_SLTSTA_PDC | PCI_EXP_SLTSTA_DLLSC))
                pciehp_handle_presence_or_link_change(ctrl, events);
        up_read(&ctrl->reset_lock);

        ret = IRQ_HANDLED;
out:
        pci_config_pm_runtime_put(pdev);
        ctrl->ist_running = false;
        wake_up(&ctrl->requester);
        return ret;
}

static int pciehp_poll(void *data)
{
        struct controller *ctrl = data;

        schedule_timeout_idle(10 * HZ); /* start with 10 sec delay */

        while (!kthread_should_stop()) {
                /* poll for interrupt events or user requests */
                while (pciehp_isr(IRQ_NOTCONNECTED, ctrl) == IRQ_WAKE_THREAD ||
                       atomic_read(&ctrl->pending_events))
                        pciehp_ist(IRQ_NOTCONNECTED, ctrl);

                if (pciehp_poll_time <= 0 || pciehp_poll_time > 60)
                        pciehp_poll_time = 2; /* clamp to sane value */

                schedule_timeout_idle(pciehp_poll_time * HZ);
        }

        return 0;
}

static void pcie_enable_notification(struct controller *ctrl)
{
        u16 cmd, mask;

        /*
         * TBD: Power fault detected software notification support.
         *
         * Power fault detected software notification is not enabled
         * now, because it caused power fault detected interrupt storm
         * on some machines. On those machines, power fault detected
         * bit in the slot status register was set again immediately
         * when it is cleared in the interrupt service routine, and
         * next power fault detected interrupt was notified again.
         */

        /*
         * Always enable link events: thus link-up and link-down shall
         * always be treated as hotplug and unplug respectively. Enable
         * presence detect only if Attention Button is not present.
         */
        cmd = PCI_EXP_SLTCTL_DLLSCE;
        if (ATTN_BUTTN(ctrl))
                cmd |= PCI_EXP_SLTCTL_ABPE;
        else
                cmd |= PCI_EXP_SLTCTL_PDCE;
        if (!pciehp_poll_mode)
                cmd |= PCI_EXP_SLTCTL_HPIE;
        if (!pciehp_poll_mode && !NO_CMD_CMPL(ctrl))
                cmd |= PCI_EXP_SLTCTL_CCIE;

        mask = (PCI_EXP_SLTCTL_PDCE | PCI_EXP_SLTCTL_ABPE |
                PCI_EXP_SLTCTL_PFDE |
                PCI_EXP_SLTCTL_HPIE | PCI_EXP_SLTCTL_CCIE |
                PCI_EXP_SLTCTL_DLLSCE);

        pcie_write_cmd_nowait(ctrl, cmd, mask);
        ctrl_dbg(ctrl, "%s: SLOTCTRL %x write cmd %x\n", __func__,
                 pci_pcie_cap(ctrl->pcie->port) + PCI_EXP_SLTCTL, cmd);
}

static void pcie_disable_notification(struct controller *ctrl)
{
        u16 mask;

        mask = (PCI_EXP_SLTCTL_PDCE | PCI_EXP_SLTCTL_ABPE |
                PCI_EXP_SLTCTL_MRLSCE | PCI_EXP_SLTCTL_PFDE |
                PCI_EXP_SLTCTL_HPIE | PCI_EXP_SLTCTL_CCIE |
                PCI_EXP_SLTCTL_DLLSCE);
        pcie_write_cmd(ctrl, 0, mask);
        ctrl_dbg(ctrl, "%s: SLOTCTRL %x write cmd %x\n", __func__,
                 pci_pcie_cap(ctrl->pcie->port) + PCI_EXP_SLTCTL, 0);
}

void pcie_clear_hotplug_events(struct controller *ctrl)
{
        pcie_capability_write_word(ctrl_dev(ctrl), PCI_EXP_SLTSTA,
                                   PCI_EXP_SLTSTA_PDC | PCI_EXP_SLTSTA_DLLSC);
}

void pcie_enable_interrupt(struct controller *ctrl)
{
        u16 mask;

        mask = PCI_EXP_SLTCTL_DLLSCE;
        if (!pciehp_poll_mode)
                mask |= PCI_EXP_SLTCTL_HPIE;
        pcie_write_cmd(ctrl, mask, mask);
}

void pcie_disable_interrupt(struct controller *ctrl)
{
        u16 mask;

        /*
         * Mask hot-plug interrupt to prevent it triggering immediately
         * when the link goes inactive (we still get PME when any of the
         * enabled events is detected). Same goes with Link Layer State
         * changed event which generates PME immediately when the link goes
         * inactive so mask it as well.
         */
        mask = PCI_EXP_SLTCTL_HPIE | PCI_EXP_SLTCTL_DLLSCE;
        pcie_write_cmd(ctrl, 0, mask);
}

/**
 * pciehp_slot_reset() - ignore link event caused by error-induced hot reset
 * @dev: PCI Express port service device
 *
 * Called from pcie_portdrv_slot_reset() after AER or DPC initiated a reset
 * further up in the hierarchy to recover from an error.  The reset was
 * propagated down to this hotplug port.  Ignore the resulting link flap.
 * If the link failed to retrain successfully, synthesize the ignored event.
 * Surprise removal during reset is detected through Presence Detect Changed.
 */
int pciehp_slot_reset(struct pcie_device *dev)
{
        struct controller *ctrl = get_service_data(dev);

        if (ctrl->state != ON_STATE)
                return 0;

        pcie_capability_write_word(dev->port, PCI_EXP_SLTSTA,
                                   PCI_EXP_SLTSTA_DLLSC);

        if (!pciehp_check_link_active(ctrl))
                pciehp_request(ctrl, PCI_EXP_SLTSTA_DLLSC);

        return 0;
}

/*
 * pciehp has a 1:1 bus:slot relationship so we ultimately want a secondary
 * bus reset of the bridge, but at the same time we want to ensure that it is
 * not seen as a hot-unplug, followed by the hot-plug of the device. Thus,
 * disable link state notification and presence detection change notification
 * momentarily, if we see that they could interfere. Also, clear any spurious
 * events after.
 */
int pciehp_reset_slot(struct hotplug_slot *hotplug_slot, bool probe)
{
        struct controller *ctrl = to_ctrl(hotplug_slot);
        struct pci_dev *pdev = ctrl_dev(ctrl);
        int rc;

        if (probe)
                return 0;

        down_write_nested(&ctrl->reset_lock, ctrl->depth);

        pci_hp_ignore_link_change(pdev);

        rc = pci_bridge_secondary_bus_reset(ctrl->pcie->port);

        pci_hp_unignore_link_change(pdev);

        up_write(&ctrl->reset_lock);
        return rc;
}

int pcie_init_notification(struct controller *ctrl)
{
        if (pciehp_request_irq(ctrl))
                return -1;
        pcie_enable_notification(ctrl);
        ctrl->notification_enabled = 1;
        return 0;
}

void pcie_shutdown_notification(struct controller *ctrl)
{
        if (ctrl->notification_enabled) {
                pcie_disable_notification(ctrl);
                pciehp_free_irq(ctrl);
                ctrl->notification_enabled = 0;
        }
}

static inline void dbg_ctrl(struct controller *ctrl)
{
        struct pci_dev *pdev = ctrl->pcie->port;
        u16 reg16;

        ctrl_dbg(ctrl, "Slot Capabilities      : 0x%08x\n", ctrl->slot_cap);
        pcie_capability_read_word(pdev, PCI_EXP_SLTSTA, &reg16);
        ctrl_dbg(ctrl, "Slot Status            : 0x%04x\n", reg16);
        pcie_capability_read_word(pdev, PCI_EXP_SLTCTL, &reg16);
        ctrl_dbg(ctrl, "Slot Control           : 0x%04x\n", reg16);
}

#define FLAG(x, y)      (((x) & (y)) ? '+' : '-')

static inline int pcie_hotplug_depth(struct pci_dev *dev)
{
        struct pci_bus *bus = dev->bus;
        int depth = 0;

        while (bus->parent) {
                bus = bus->parent;
                if (bus->self && bus->self->is_pciehp)
                        depth++;
        }

        return depth;
}

struct controller *pcie_init(struct pcie_device *dev)
{
        struct controller *ctrl;
        u32 slot_cap, slot_cap2;
        u8 poweron;
        struct pci_dev *pdev = dev->port;
        struct pci_bus *subordinate = pdev->subordinate;

        ctrl = kzalloc_obj(*ctrl);
        if (!ctrl)
                return NULL;

        ctrl->pcie = dev;
        ctrl->depth = pcie_hotplug_depth(dev->port);
        pcie_capability_read_dword(pdev, PCI_EXP_SLTCAP, &slot_cap);

        if (pdev->hotplug_user_indicators)
                slot_cap &= ~(PCI_EXP_SLTCAP_AIP | PCI_EXP_SLTCAP_PIP);

        /*
         * We assume no Thunderbolt controllers support Command Complete events,
         * but some controllers falsely claim they do.
         */
        if (pdev->is_thunderbolt)
                slot_cap |= PCI_EXP_SLTCAP_NCCS;

        ctrl->slot_cap = slot_cap;
        mutex_init(&ctrl->ctrl_lock);
        mutex_init(&ctrl->state_lock);
        init_rwsem(&ctrl->reset_lock);
        init_waitqueue_head(&ctrl->requester);
        init_waitqueue_head(&ctrl->queue);
        INIT_DELAYED_WORK(&ctrl->button_work, pciehp_queue_pushbutton_work);
        dbg_ctrl(ctrl);

        down_read(&pci_bus_sem);
        ctrl->state = list_empty(&subordinate->devices) ? OFF_STATE : ON_STATE;
        up_read(&pci_bus_sem);

        pcie_capability_read_dword(pdev, PCI_EXP_SLTCAP2, &slot_cap2);
        if (slot_cap2 & PCI_EXP_SLTCAP2_IBPD) {
                pcie_write_cmd_nowait(ctrl, PCI_EXP_SLTCTL_IBPD_DISABLE,
                                      PCI_EXP_SLTCTL_IBPD_DISABLE);
                ctrl->inband_presence_disabled = 1;
        }

        if (dmi_first_match(inband_presence_disabled_dmi_table))
                ctrl->inband_presence_disabled = 1;

        /* Clear all remaining event bits in Slot Status register. */
        pcie_capability_write_word(pdev, PCI_EXP_SLTSTA,
                PCI_EXP_SLTSTA_ABP | PCI_EXP_SLTSTA_PFD |
                PCI_EXP_SLTSTA_MRLSC | PCI_EXP_SLTSTA_CC |
                PCI_EXP_SLTSTA_DLLSC | PCI_EXP_SLTSTA_PDC);

        ctrl_info(ctrl, "Slot #%d AttnBtn%c PwrCtrl%c MRL%c AttnInd%c PwrInd%c HotPlug%c Surprise%c Interlock%c NoCompl%c IbPresDis%c LLActRep%c%s\n",
                FIELD_GET(PCI_EXP_SLTCAP_PSN, slot_cap),
                FLAG(slot_cap, PCI_EXP_SLTCAP_ABP),
                FLAG(slot_cap, PCI_EXP_SLTCAP_PCP),
                FLAG(slot_cap, PCI_EXP_SLTCAP_MRLSP),
                FLAG(slot_cap, PCI_EXP_SLTCAP_AIP),
                FLAG(slot_cap, PCI_EXP_SLTCAP_PIP),
                FLAG(slot_cap, PCI_EXP_SLTCAP_HPC),
                FLAG(slot_cap, PCI_EXP_SLTCAP_HPS),
                FLAG(slot_cap, PCI_EXP_SLTCAP_EIP),
                FLAG(slot_cap, PCI_EXP_SLTCAP_NCCS),
                FLAG(slot_cap2, PCI_EXP_SLTCAP2_IBPD),
                FLAG(pdev->link_active_reporting, true),
                pdev->broken_cmd_compl ? " (with Cmd Compl erratum)" : "");

        /*
         * If empty slot's power status is on, turn power off.  The IRQ isn't
         * requested yet, so avoid triggering a notification with this command.
         */
        if (POWER_CTRL(ctrl)) {
                pciehp_get_power_status(ctrl, &poweron);
                if (!pciehp_card_present_or_link_active(ctrl) && poweron) {
                        pcie_disable_notification(ctrl);
                        pciehp_power_off_slot(ctrl);
                }
        }

        pdev = pci_get_slot(subordinate, PCI_DEVFN(0, 0));
        if (pdev)
                ctrl->dsn = pci_get_dsn(pdev);
        pci_dev_put(pdev);

        return ctrl;
}

void pciehp_release_ctrl(struct controller *ctrl)
{
        cancel_delayed_work_sync(&ctrl->button_work);
        kfree(ctrl);
}

static void quirk_cmd_compl(struct pci_dev *pdev)
{
        u32 slot_cap;

        if (pci_is_pcie(pdev)) {
                pcie_capability_read_dword(pdev, PCI_EXP_SLTCAP, &slot_cap);
                if (slot_cap & PCI_EXP_SLTCAP_HPC &&
                    !(slot_cap & PCI_EXP_SLTCAP_NCCS))
                        pdev->broken_cmd_compl = 1;
        }
}
DECLARE_PCI_FIXUP_CLASS_EARLY(PCI_VENDOR_ID_INTEL, PCI_ANY_ID,
                              PCI_CLASS_BRIDGE_PCI, 8, quirk_cmd_compl);
DECLARE_PCI_FIXUP_CLASS_EARLY(PCI_VENDOR_ID_QCOM, 0x010e,
                              PCI_CLASS_BRIDGE_PCI, 8, quirk_cmd_compl);
DECLARE_PCI_FIXUP_CLASS_EARLY(PCI_VENDOR_ID_QCOM, 0x0110,
                              PCI_CLASS_BRIDGE_PCI, 8, quirk_cmd_compl);
DECLARE_PCI_FIXUP_CLASS_EARLY(PCI_VENDOR_ID_QCOM, 0x0400,
                              PCI_CLASS_BRIDGE_PCI, 8, quirk_cmd_compl);
DECLARE_PCI_FIXUP_CLASS_EARLY(PCI_VENDOR_ID_QCOM, 0x0401,
                              PCI_CLASS_BRIDGE_PCI, 8, quirk_cmd_compl);
DECLARE_PCI_FIXUP_CLASS_EARLY(PCI_VENDOR_ID_HXT, 0x0401,
                              PCI_CLASS_BRIDGE_PCI, 8, quirk_cmd_compl);