/*
 * PCI Error Recovery Driver for RPA-compliant PPC64 platform.
 * Copyright IBM Corp. 2004 2005
 * Copyright Linas Vepstas <linas@linas.org> 2004, 2005
 *
 * All rights reserved.
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or (at
 * your option) any later version.
 *
 * This program is distributed in the hope that it will be useful, but
 * WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE, GOOD TITLE or
 * NON INFRINGEMENT.  See the GNU General Public License for more
 * details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
 *
 * Send comments and feedback to Linas Vepstas <linas@austin.ibm.com>
 */
#include <linux/delay.h>
#include <linux/interrupt.h>
#include <linux/irq.h>
#include <linux/module.h>
#include <linux/pci.h>
#include <linux/pci_hotplug.h>
#include <asm/eeh.h>
#include <asm/eeh_event.h>
#include <asm/ppc-pci.h>
#include <asm/pci-bridge.h>
#include <asm/prom.h>
#include <asm/rtas.h>

struct eeh_rmv_data {
        struct list_head removed_vf_list;
        int removed_dev_count;
};

static int eeh_result_priority(enum pci_ers_result result)
{
        switch (result) {
        case PCI_ERS_RESULT_NONE:
                return 1;
        case PCI_ERS_RESULT_NO_AER_DRIVER:
                return 2;
        case PCI_ERS_RESULT_RECOVERED:
                return 3;
        case PCI_ERS_RESULT_CAN_RECOVER:
                return 4;
        case PCI_ERS_RESULT_DISCONNECT:
                return 5;
        case PCI_ERS_RESULT_NEED_RESET:
                return 6;
        default:
                WARN_ONCE(1, "Unknown pci_ers_result value: %d\n", (int)result);
                return 0;
        }
};

static const char *pci_ers_result_name(enum pci_ers_result result)
{
        switch (result) {
        case PCI_ERS_RESULT_NONE:
                return "none";
        case PCI_ERS_RESULT_CAN_RECOVER:
                return "can recover";
        case PCI_ERS_RESULT_NEED_RESET:
                return "need reset";
        case PCI_ERS_RESULT_DISCONNECT:
                return "disconnect";
        case PCI_ERS_RESULT_RECOVERED:
                return "recovered";
        case PCI_ERS_RESULT_NO_AER_DRIVER:
                return "no AER driver";
        default:
                WARN_ONCE(1, "Unknown result type: %d\n", (int)result);
                return "unknown";
        }
};

static enum pci_ers_result pci_ers_merge_result(enum pci_ers_result old,
                                                enum pci_ers_result new)
{
        if (eeh_result_priority(new) > eeh_result_priority(old))
                return new;
        return old;
}

static bool eeh_dev_removed(struct eeh_dev *edev)
{
        return !edev || (edev->mode & EEH_DEV_REMOVED);
}

static bool eeh_edev_actionable(struct eeh_dev *edev)
{
        if (!edev->pdev)
                return false;
        if (edev->pdev->error_state == pci_channel_io_perm_failure)
                return false;
        if (eeh_dev_removed(edev))
                return false;
        if (eeh_pe_passed(edev->pe))
                return false;

        return true;
}

/**
 * eeh_pcid_get - Get the PCI device driver
 * @pdev: PCI device
 *
 * The function is used to retrieve the PCI device driver for
 * the indicated PCI device. Besides, we will increase the reference
 * of the PCI device driver to prevent that being unloaded on
 * the fly. Otherwise, kernel crash would be seen.
 */
static inline struct pci_driver *eeh_pcid_get(struct pci_dev *pdev)
{
        if (!pdev || !pdev->driver)
                return NULL;

        if (!try_module_get(pdev->driver->driver.owner))
                return NULL;

        return pdev->driver;
}

/**
 * eeh_pcid_put - Dereference on the PCI device driver
 * @pdev: PCI device
 *
 * The function is called to do dereference on the PCI device
 * driver of the indicated PCI device.
 */
static inline void eeh_pcid_put(struct pci_dev *pdev)
{
        if (!pdev || !pdev->driver)
                return;

        module_put(pdev->driver->driver.owner);
}

/**
 * eeh_disable_irq - Disable interrupt for the recovering device
 * @dev: PCI device
 *
 * This routine must be called when reporting temporary or permanent
 * error to the particular PCI device to disable interrupt of that
 * device. If the device has enabled MSI or MSI-X interrupt, we needn't
 * do real work because EEH should freeze DMA transfers for those PCI
 * devices encountering EEH errors, which includes MSI or MSI-X.
 */
static void eeh_disable_irq(struct eeh_dev *edev)
{
        /* Don't disable MSI and MSI-X interrupts. They are
         * effectively disabled by the DMA Stopped state
         * when an EEH error occurs.
         */
        if (edev->pdev->msi_enabled || edev->pdev->msix_enabled)
                return;

        if (!irq_has_action(edev->pdev->irq))
                return;

        edev->mode |= EEH_DEV_IRQ_DISABLED;
        disable_irq_nosync(edev->pdev->irq);
}

/**
 * eeh_enable_irq - Enable interrupt for the recovering device
 * @dev: PCI device
 *
 * This routine must be called to enable interrupt while failed
 * device could be resumed.
 */
static void eeh_enable_irq(struct eeh_dev *edev)
{
        if ((edev->mode) & EEH_DEV_IRQ_DISABLED) {
                edev->mode &= ~EEH_DEV_IRQ_DISABLED;
                /*
                 * FIXME !!!!!
                 *
                 * This is just ass backwards. This maze has
                 * unbalanced irq_enable/disable calls. So instead of
                 * finding the root cause it works around the warning
                 * in the irq_enable code by conditionally calling
                 * into it.
                 *
                 * That's just wrong.The warning in the core code is
                 * there to tell people to fix their asymmetries in
                 * their own code, not by abusing the core information
                 * to avoid it.
                 *
                 * I so wish that the assymetry would be the other way
                 * round and a few more irq_disable calls render that
                 * shit unusable forever.
                 *
                 *      tglx
                 */
                if (irqd_irq_disabled(irq_get_irq_data(edev->pdev->irq)))
                        enable_irq(edev->pdev->irq);
        }
}

static void eeh_dev_save_state(struct eeh_dev *edev, void *userdata)
{
        struct pci_dev *pdev;

        if (!edev)
                return;

        /*
         * We cannot access the config space on some adapters.
         * Otherwise, it will cause fenced PHB. We don't save
         * the content in their config space and will restore
         * from the initial config space saved when the EEH
         * device is created.
         */
        if (edev->pe && (edev->pe->state & EEH_PE_CFG_RESTRICTED))
                return;

        pdev = eeh_dev_to_pci_dev(edev);
        if (!pdev)
                return;

        pci_save_state(pdev);
}

static void eeh_set_channel_state(struct eeh_pe *root, enum pci_channel_state s)
{
        struct eeh_pe *pe;
        struct eeh_dev *edev, *tmp;

        eeh_for_each_pe(root, pe)
                eeh_pe_for_each_dev(pe, edev, tmp)
                        if (eeh_edev_actionable(edev))
                                edev->pdev->error_state = s;
}

static void eeh_set_irq_state(struct eeh_pe *root, bool enable)
{
        struct eeh_pe *pe;
        struct eeh_dev *edev, *tmp;

        eeh_for_each_pe(root, pe) {
                eeh_pe_for_each_dev(pe, edev, tmp) {
                        if (!eeh_edev_actionable(edev))
                                continue;

                        if (!eeh_pcid_get(edev->pdev))
                                continue;

                        if (enable)
                                eeh_enable_irq(edev);
                        else
                                eeh_disable_irq(edev);

                        eeh_pcid_put(edev->pdev);
                }
        }
}

typedef enum pci_ers_result (*eeh_report_fn)(struct eeh_dev *,
                                             struct pci_dev *,
                                             struct pci_driver *);
static void eeh_pe_report_edev(struct eeh_dev *edev, eeh_report_fn fn,
                               enum pci_ers_result *result)
{
        struct pci_dev *pdev;
        struct pci_driver *driver;
        enum pci_ers_result new_result;

        pci_lock_rescan_remove();
        pdev = edev->pdev;
        if (pdev)
                get_device(&pdev->dev);
        pci_unlock_rescan_remove();
        if (!pdev) {
                eeh_edev_info(edev, "no device");
                return;
        }
        device_lock(&pdev->dev);
        if (eeh_edev_actionable(edev)) {
                driver = eeh_pcid_get(pdev);

                if (!driver)
                        eeh_edev_info(edev, "no driver");
                else if (!driver->err_handler)
                        eeh_edev_info(edev, "driver not EEH aware");
                else if (edev->mode & EEH_DEV_NO_HANDLER)
                        eeh_edev_info(edev, "driver bound too late");
                else {
                        new_result = fn(edev, pdev, driver);
                        eeh_edev_info(edev, "%s driver reports: '%s'",
                                      driver->name,
                                      pci_ers_result_name(new_result));
                        if (result)
                                *result = pci_ers_merge_result(*result,
                                                               new_result);
                }
                if (driver)
                        eeh_pcid_put(pdev);
        } else {
                eeh_edev_info(edev, "not actionable (%d,%d,%d)", !!pdev,
                              !eeh_dev_removed(edev), !eeh_pe_passed(edev->pe));
        }
        device_unlock(&pdev->dev);
        if (edev->pdev != pdev)
                eeh_edev_warn(edev, "Device changed during processing!\n");
        put_device(&pdev->dev);
}

static void eeh_pe_report(const char *name, struct eeh_pe *root,
                          eeh_report_fn fn, enum pci_ers_result *result)
{
        struct eeh_pe *pe;
        struct eeh_dev *edev, *tmp;

        pr_info("EEH: Beginning: '%s'\n", name);
        eeh_for_each_pe(root, pe) eeh_pe_for_each_dev(pe, edev, tmp)
                eeh_pe_report_edev(edev, fn, result);
        if (result)
                pr_info("EEH: Finished:'%s' with aggregate recovery state:'%s'\n",
                        name, pci_ers_result_name(*result));
        else
                pr_info("EEH: Finished:'%s'", name);
}

/**
 * eeh_report_error - Report pci error to each device driver
 * @edev: eeh device
 * @driver: device's PCI driver
 *
 * Report an EEH error to each device driver.
 */
static enum pci_ers_result eeh_report_error(struct eeh_dev *edev,
                                            struct pci_dev *pdev,
                                            struct pci_driver *driver)
{
        enum pci_ers_result rc;

        if (!driver->err_handler->error_detected)
                return PCI_ERS_RESULT_NONE;

        eeh_edev_info(edev, "Invoking %s->error_detected(IO frozen)",
                      driver->name);
        rc = driver->err_handler->error_detected(pdev, pci_channel_io_frozen);

        edev->in_error = true;
        pci_uevent_ers(pdev, PCI_ERS_RESULT_NONE);
        return rc;
}

/**
 * eeh_report_mmio_enabled - Tell drivers that MMIO has been enabled
 * @edev: eeh device
 * @driver: device's PCI driver
 *
 * Tells each device driver that IO ports, MMIO and config space I/O
 * are now enabled.
 */
static enum pci_ers_result eeh_report_mmio_enabled(struct eeh_dev *edev,
                                                   struct pci_dev *pdev,
                                                   struct pci_driver *driver)
{
        if (!driver->err_handler->mmio_enabled)
                return PCI_ERS_RESULT_NONE;
        eeh_edev_info(edev, "Invoking %s->mmio_enabled()", driver->name);
        return driver->err_handler->mmio_enabled(pdev);
}

/**
 * eeh_report_reset - Tell device that slot has been reset
 * @edev: eeh device
 * @driver: device's PCI driver
 *
 * This routine must be called while EEH tries to reset particular
 * PCI device so that the associated PCI device driver could take
 * some actions, usually to save data the driver needs so that the
 * driver can work again while the device is recovered.
 */
static enum pci_ers_result eeh_report_reset(struct eeh_dev *edev,
                                            struct pci_dev *pdev,
                                            struct pci_driver *driver)
{
        if (!driver->err_handler->slot_reset || !edev->in_error)
                return PCI_ERS_RESULT_NONE;
        eeh_edev_info(edev, "Invoking %s->slot_reset()", driver->name);
        return driver->err_handler->slot_reset(pdev);
}

static void eeh_dev_restore_state(struct eeh_dev *edev, void *userdata)
{
        struct pci_dev *pdev;

        if (!edev)
                return;

        /*
         * The content in the config space isn't saved because
         * the blocked config space on some adapters. We have
         * to restore the initial saved config space when the
         * EEH device is created.
         */
        if (edev->pe && (edev->pe->state & EEH_PE_CFG_RESTRICTED)) {
                if (list_is_last(&edev->entry, &edev->pe->edevs))
                        eeh_pe_restore_bars(edev->pe);

                return;
        }

        pdev = eeh_dev_to_pci_dev(edev);
        if (!pdev)
                return;

        pci_restore_state(pdev);
}

/**
 * eeh_report_resume - Tell device to resume normal operations
 * @edev: eeh device
 * @driver: device's PCI driver
 *
 * This routine must be called to notify the device driver that it
 * could resume so that the device driver can do some initialization
 * to make the recovered device work again.
 */
static enum pci_ers_result eeh_report_resume(struct eeh_dev *edev,
                                             struct pci_dev *pdev,
                                             struct pci_driver *driver)
{
        if (!driver->err_handler->resume || !edev->in_error)
                return PCI_ERS_RESULT_NONE;

        eeh_edev_info(edev, "Invoking %s->resume()", driver->name);
        driver->err_handler->resume(pdev);

        pci_uevent_ers(edev->pdev, PCI_ERS_RESULT_RECOVERED);
#ifdef CONFIG_PCI_IOV
        if (eeh_ops->notify_resume && eeh_dev_to_pdn(edev))
                eeh_ops->notify_resume(eeh_dev_to_pdn(edev));
#endif
        return PCI_ERS_RESULT_NONE;
}

/**
 * eeh_report_failure - Tell device driver that device is dead.
 * @edev: eeh device
 * @driver: device's PCI driver
 *
 * This informs the device driver that the device is permanently
 * dead, and that no further recovery attempts will be made on it.
 */
static enum pci_ers_result eeh_report_failure(struct eeh_dev *edev,
                                              struct pci_dev *pdev,
                                              struct pci_driver *driver)
{
        enum pci_ers_result rc;

        if (!driver->err_handler->error_detected)
                return PCI_ERS_RESULT_NONE;

        eeh_edev_info(edev, "Invoking %s->error_detected(permanent failure)",
                      driver->name);
        rc = driver->err_handler->error_detected(pdev,
                                                 pci_channel_io_perm_failure);

        pci_uevent_ers(pdev, PCI_ERS_RESULT_DISCONNECT);
        return rc;
}

static void *eeh_add_virt_device(struct eeh_dev *edev)
{
        struct pci_driver *driver;
        struct pci_dev *dev = eeh_dev_to_pci_dev(edev);

        if (!(edev->physfn)) {
                eeh_edev_warn(edev, "Not for VF\n");
                return NULL;
        }

        driver = eeh_pcid_get(dev);
        if (driver) {
                if (driver->err_handler) {
                        eeh_pcid_put(dev);
                        return NULL;
                }
                eeh_pcid_put(dev);
        }

#ifdef CONFIG_PCI_IOV
        pci_iov_add_virtfn(edev->physfn, eeh_dev_to_pdn(edev)->vf_index);
#endif
        return NULL;
}

static void eeh_rmv_device(struct eeh_dev *edev, void *userdata)
{
        struct pci_driver *driver;
        struct pci_dev *dev = eeh_dev_to_pci_dev(edev);
        struct eeh_rmv_data *rmv_data = (struct eeh_rmv_data *)userdata;

        /*
         * Actually, we should remove the PCI bridges as well.
         * However, that's lots of complexity to do that,
         * particularly some of devices under the bridge might
         * support EEH. So we just care about PCI devices for
         * simplicity here.
         */
        if (!eeh_edev_actionable(edev) ||
            (dev->hdr_type == PCI_HEADER_TYPE_BRIDGE))
                return;

        if (rmv_data) {
                driver = eeh_pcid_get(dev);
                if (driver) {
                        if (driver->err_handler &&
                            driver->err_handler->error_detected &&
                            driver->err_handler->slot_reset) {
                                eeh_pcid_put(dev);
                                return;
                        }
                        eeh_pcid_put(dev);
                }
        }

        /* Remove it from PCI subsystem */
        pr_info("EEH: Removing %s without EEH sensitive driver\n",
                pci_name(dev));
        edev->mode |= EEH_DEV_DISCONNECTED;
        if (rmv_data)
                rmv_data->removed_dev_count++;

        if (edev->physfn) {
#ifdef CONFIG_PCI_IOV
                struct pci_dn *pdn = eeh_dev_to_pdn(edev);

                pci_iov_remove_virtfn(edev->physfn, pdn->vf_index);
                edev->pdev = NULL;

                /*
                 * We have to set the VF PE number to invalid one, which is
                 * required to plug the VF successfully.
                 */
                pdn->pe_number = IODA_INVALID_PE;
#endif
                if (rmv_data)
                        list_add(&edev->rmv_entry, &rmv_data->removed_vf_list);
        } else {
                pci_lock_rescan_remove();
                pci_stop_and_remove_bus_device(dev);
                pci_unlock_rescan_remove();
        }
}

static void *eeh_pe_detach_dev(struct eeh_pe *pe, void *userdata)
{
        struct eeh_dev *edev, *tmp;

        eeh_pe_for_each_dev(pe, edev, tmp) {
                if (!(edev->mode & EEH_DEV_DISCONNECTED))
                        continue;

                edev->mode &= ~(EEH_DEV_DISCONNECTED | EEH_DEV_IRQ_DISABLED);
                eeh_rmv_from_parent_pe(edev);
        }

        return NULL;
}

/*
 * Explicitly clear PE's frozen state for PowerNV where
 * we have frozen PE until BAR restore is completed. It's
 * harmless to clear it for pSeries. To be consistent with
 * PE reset (for 3 times), we try to clear the frozen state
 * for 3 times as well.
 */
static int eeh_clear_pe_frozen_state(struct eeh_pe *root, bool include_passed)
{
        struct eeh_pe *pe;
        int i;

        eeh_for_each_pe(root, pe) {
                if (include_passed || !eeh_pe_passed(pe)) {
                        for (i = 0; i < 3; i++)
                                if (!eeh_unfreeze_pe(pe))
                                        break;
                        if (i >= 3)
                                return -EIO;
                }
        }
        eeh_pe_state_clear(root, EEH_PE_ISOLATED, include_passed);
        return 0;
}

int eeh_pe_reset_and_recover(struct eeh_pe *pe)
{
        int ret;

        /* Bail if the PE is being recovered */
        if (pe->state & EEH_PE_RECOVERING)
                return 0;

        /* Put the PE into recovery mode */
        eeh_pe_state_mark(pe, EEH_PE_RECOVERING);

        /* Save states */
        eeh_pe_dev_traverse(pe, eeh_dev_save_state, NULL);

        /* Issue reset */
        ret = eeh_pe_reset_full(pe, true);
        if (ret) {
                eeh_pe_state_clear(pe, EEH_PE_RECOVERING, true);
                return ret;
        }

        /* Unfreeze the PE */
        ret = eeh_clear_pe_frozen_state(pe, true);
        if (ret) {
                eeh_pe_state_clear(pe, EEH_PE_RECOVERING, true);
                return ret;
        }

        /* Restore device state */
        eeh_pe_dev_traverse(pe, eeh_dev_restore_state, NULL);

        /* Clear recovery mode */
        eeh_pe_state_clear(pe, EEH_PE_RECOVERING, true);

        return 0;
}

/**
 * eeh_reset_device - Perform actual reset of a pci slot
 * @driver_eeh_aware: Does the device's driver provide EEH support?
 * @pe: EEH PE
 * @bus: PCI bus corresponding to the isolcated slot
 * @rmv_data: Optional, list to record removed devices
 *
 * This routine must be called to do reset on the indicated PE.
 * During the reset, udev might be invoked because those affected
 * PCI devices will be removed and then added.
 */
static int eeh_reset_device(struct eeh_pe *pe, struct pci_bus *bus,
                            struct eeh_rmv_data *rmv_data,
                            bool driver_eeh_aware)
{
        time64_t tstamp;
        int cnt, rc;
        struct eeh_dev *edev;
        struct eeh_pe *tmp_pe;
        bool any_passed = false;

        eeh_for_each_pe(pe, tmp_pe)
                any_passed |= eeh_pe_passed(tmp_pe);

        /* pcibios will clear the counter; save the value */
        cnt = pe->freeze_count;
        tstamp = pe->tstamp;

        /*
         * We don't remove the corresponding PE instances because
         * we need the information afterwords. The attached EEH
         * devices are expected to be attached soon when calling
         * into pci_hp_add_devices().
         */
        eeh_pe_state_mark(pe, EEH_PE_KEEP);
        if (any_passed || driver_eeh_aware || (pe->type & EEH_PE_VF)) {
                eeh_pe_dev_traverse(pe, eeh_rmv_device, rmv_data);
        } else {
                pci_lock_rescan_remove();
                pci_hp_remove_devices(bus);
                pci_unlock_rescan_remove();
        }

        /*
         * Reset the pci controller. (Asserts RST#; resets config space).
         * Reconfigure bridges and devices. Don't try to bring the system
         * up if the reset failed for some reason.
         *
         * During the reset, it's very dangerous to have uncontrolled PCI
         * config accesses. So we prefer to block them. However, controlled
         * PCI config accesses initiated from EEH itself are allowed.
         */
        rc = eeh_pe_reset_full(pe, false);
        if (rc)
                return rc;

        pci_lock_rescan_remove();

        /* Restore PE */
        eeh_ops->configure_bridge(pe);
        eeh_pe_restore_bars(pe);

        /* Clear frozen state */
        rc = eeh_clear_pe_frozen_state(pe, false);
        if (rc) {
                pci_unlock_rescan_remove();
                return rc;
        }

        /* Give the system 5 seconds to finish running the user-space
         * hotplug shutdown scripts, e.g. ifdown for ethernet.  Yes,
         * this is a hack, but if we don't do this, and try to bring
         * the device up before the scripts have taken it down,
         * potentially weird things happen.
         */
        if (!driver_eeh_aware || rmv_data->removed_dev_count) {
                pr_info("EEH: Sleep 5s ahead of %s hotplug\n",
                        (driver_eeh_aware ? "partial" : "complete"));
                ssleep(5);

                /*
                 * The EEH device is still connected with its parent
                 * PE. We should disconnect it so the binding can be
                 * rebuilt when adding PCI devices.
                 */
                edev = list_first_entry(&pe->edevs, struct eeh_dev, entry);
                eeh_pe_traverse(pe, eeh_pe_detach_dev, NULL);
                if (pe->type & EEH_PE_VF) {
                        eeh_add_virt_device(edev);
                } else {
                        if (!driver_eeh_aware)
                                eeh_pe_state_clear(pe, EEH_PE_PRI_BUS, true);
                        pci_hp_add_devices(bus);
                }
        }
        eeh_pe_state_clear(pe, EEH_PE_KEEP, true);

        pe->tstamp = tstamp;
        pe->freeze_count = cnt;

        pci_unlock_rescan_remove();
        return 0;
}

/* The longest amount of time to wait for a pci device
 * to come back on line, in seconds.
 */
#define MAX_WAIT_FOR_RECOVERY 300


/* Walks the PE tree after processing an event to remove any stale PEs.
 *
 * NB: This needs to be recursive to ensure the leaf PEs get removed
 * before their parents do. Although this is possible to do recursively
 * we don't since this is easier to read and we need to garantee
 * the leaf nodes will be handled first.
 */
static void eeh_pe_cleanup(struct eeh_pe *pe)
{
        struct eeh_pe *child_pe, *tmp;

        list_for_each_entry_safe(child_pe, tmp, &pe->child_list, child)
                eeh_pe_cleanup(child_pe);

        if (pe->state & EEH_PE_KEEP)
                return;

        if (!(pe->state & EEH_PE_INVALID))
                return;

        if (list_empty(&pe->edevs) && list_empty(&pe->child_list)) {
                list_del(&pe->child);
                kfree(pe);
        }
}

/**
 * eeh_check_slot_presence - Check if a device is still present in a slot
 * @pdev: pci_dev to check
 *
 * This function may return a false positive if we can't determine the slot's
 * presence state. This might happen for for PCIe slots if the PE containing
 * the upstream bridge is also frozen, or the bridge is part of the same PE
 * as the device.
 *
 * This shouldn't happen often, but you might see it if you hotplug a PCIe
 * switch.
 */
static bool eeh_slot_presence_check(struct pci_dev *pdev)
{
        const struct hotplug_slot_ops *ops;
        struct pci_slot *slot;
        u8 state;
        int rc;

        if (!pdev)
                return false;

        if (pdev->error_state == pci_channel_io_perm_failure)
                return false;

        slot = pdev->slot;
        if (!slot || !slot->hotplug)
                return true;

        ops = slot->hotplug->ops;
        if (!ops || !ops->get_adapter_status)
                return true;

        /* set the attention indicator while we've got the slot ops */
        if (ops->set_attention_status)
                ops->set_attention_status(slot->hotplug, 1);

        rc = ops->get_adapter_status(slot->hotplug, &state);
        if (rc)
                return true;

        return !!state;
}

static void eeh_clear_slot_attention(struct pci_dev *pdev)
{
        const struct hotplug_slot_ops *ops;
        struct pci_slot *slot;

        if (!pdev)
                return;

        if (pdev->error_state == pci_channel_io_perm_failure)
                return;

        slot = pdev->slot;
        if (!slot || !slot->hotplug)
                return;

        ops = slot->hotplug->ops;
        if (!ops || !ops->set_attention_status)
                return;

        ops->set_attention_status(slot->hotplug, 0);
}

/**
 * eeh_handle_normal_event - Handle EEH events on a specific PE
 * @pe: EEH PE - which should not be used after we return, as it may
 * have been invalidated.
 *
 * Attempts to recover the given PE.  If recovery fails or the PE has failed
 * too many times, remove the PE.
 *
 * While PHB detects address or data parity errors on particular PCI
 * slot, the associated PE will be frozen. Besides, DMA's occurring
 * to wild addresses (which usually happen due to bugs in device
 * drivers or in PCI adapter firmware) can cause EEH error. #SERR,
 * #PERR or other misc PCI-related errors also can trigger EEH errors.
 *
 * Recovery process consists of unplugging the device driver (which
 * generated hotplug events to userspace), then issuing a PCI #RST to
 * the device, then reconfiguring the PCI config space for all bridges
 * & devices under this slot, and then finally restarting the device
 * drivers (which cause a second set of hotplug events to go out to
 * userspace).
 */
void eeh_handle_normal_event(struct eeh_pe *pe)
{
        struct pci_bus *bus;
        struct eeh_dev *edev, *tmp;
        struct eeh_pe *tmp_pe;
        int rc = 0;
        enum pci_ers_result result = PCI_ERS_RESULT_NONE;
        struct eeh_rmv_data rmv_data =
                {LIST_HEAD_INIT(rmv_data.removed_vf_list), 0};
        int devices = 0;

        bus = eeh_pe_bus_get(pe);
        if (!bus) {
                pr_err("%s: Cannot find PCI bus for PHB#%x-PE#%x\n",
                        __func__, pe->phb->global_number, pe->addr);
                return;
        }

        /*
         * When devices are hot-removed we might get an EEH due to
         * a driver attempting to touch the MMIO space of a removed
         * device. In this case we don't have a device to recover
         * so suppress the event if we can't find any present devices.
         *
         * The hotplug driver should take care of tearing down the
         * device itself.
         */
        eeh_for_each_pe(pe, tmp_pe)
                eeh_pe_for_each_dev(tmp_pe, edev, tmp)
                        if (eeh_slot_presence_check(edev->pdev))
                                devices++;

        if (!devices) {
                pr_debug("EEH: Frozen PHB#%x-PE#%x is empty!\n",
                        pe->phb->global_number, pe->addr);
                goto out; /* nothing to recover */
        }

        /* Log the event */
        if (pe->type & EEH_PE_PHB) {
                pr_err("EEH: PHB#%x failure detected, location: %s\n",
                        pe->phb->global_number, eeh_pe_loc_get(pe));
        } else {
                struct eeh_pe *phb_pe = eeh_phb_pe_get(pe->phb);

                pr_err("EEH: Frozen PHB#%x-PE#%x detected\n",
                       pe->phb->global_number, pe->addr);
                pr_err("EEH: PE location: %s, PHB location: %s\n",
                       eeh_pe_loc_get(pe), eeh_pe_loc_get(phb_pe));
        }

#ifdef CONFIG_STACKTRACE
        /*
         * Print the saved stack trace now that we've verified there's
         * something to recover.
         */
        if (pe->trace_entries) {
                void **ptrs = (void **) pe->stack_trace;
                int i;

                pr_err("EEH: Frozen PHB#%x-PE#%x detected\n",
                       pe->phb->global_number, pe->addr);

                /* FIXME: Use the same format as dump_stack() */
                pr_err("EEH: Call Trace:\n");
                for (i = 0; i < pe->trace_entries; i++)
                        pr_err("EEH: [%pK] %pS\n", ptrs[i], ptrs[i]);

                pe->trace_entries = 0;
        }
#endif /* CONFIG_STACKTRACE */

        eeh_pe_update_time_stamp(pe);
        pe->freeze_count++;
        if (pe->freeze_count > eeh_max_freezes) {
                pr_err("EEH: PHB#%x-PE#%x has failed %d times in the last hour and has been permanently disabled.\n",
                       pe->phb->global_number, pe->addr,
                       pe->freeze_count);
                result = PCI_ERS_RESULT_DISCONNECT;
        }

        eeh_for_each_pe(pe, tmp_pe)
                eeh_pe_for_each_dev(tmp_pe, edev, tmp)
                        edev->mode &= ~EEH_DEV_NO_HANDLER;

        /* Walk the various device drivers attached to this slot through
         * a reset sequence, giving each an opportunity to do what it needs
         * to accomplish the reset.  Each child gets a report of the
         * status ... if any child can't handle the reset, then the entire
         * slot is dlpar removed and added.
         *
         * When the PHB is fenced, we have to issue a reset to recover from
         * the error. Override the result if necessary to have partially
         * hotplug for this case.
         */
        if (result != PCI_ERS_RESULT_DISCONNECT) {
                pr_warn("EEH: This PCI device has failed %d times in the last hour and will be permanently disabled after %d failures.\n",
                        pe->freeze_count, eeh_max_freezes);
                pr_info("EEH: Notify device drivers to shutdown\n");
                eeh_set_channel_state(pe, pci_channel_io_frozen);
                eeh_set_irq_state(pe, false);
                eeh_pe_report("error_detected(IO frozen)", pe,
                              eeh_report_error, &result);
                if ((pe->type & EEH_PE_PHB) &&
                    result != PCI_ERS_RESULT_NONE &&
                    result != PCI_ERS_RESULT_NEED_RESET)
                        result = PCI_ERS_RESULT_NEED_RESET;
        }

        /* Get the current PCI slot state. This can take a long time,
         * sometimes over 300 seconds for certain systems.
         */
        if (result != PCI_ERS_RESULT_DISCONNECT) {
                rc = eeh_wait_state(pe, MAX_WAIT_FOR_RECOVERY*1000);
                if (rc < 0 || rc == EEH_STATE_NOT_SUPPORT) {
                        pr_warn("EEH: Permanent failure\n");
                        result = PCI_ERS_RESULT_DISCONNECT;
                }
        }

        /* Since rtas may enable MMIO when posting the error log,
         * don't post the error log until after all dev drivers
         * have been informed.
         */
        if (result != PCI_ERS_RESULT_DISCONNECT) {
                pr_info("EEH: Collect temporary log\n");
                eeh_slot_error_detail(pe, EEH_LOG_TEMP);
        }

        /* If all device drivers were EEH-unaware, then shut
         * down all of the device drivers, and hope they
         * go down willingly, without panicing the system.
         */
        if (result == PCI_ERS_RESULT_NONE) {
                pr_info("EEH: Reset with hotplug activity\n");
                rc = eeh_reset_device(pe, bus, NULL, false);
                if (rc) {
                        pr_warn("%s: Unable to reset, err=%d\n",
                                __func__, rc);
                        result = PCI_ERS_RESULT_DISCONNECT;
                }

        }

        /* If all devices reported they can proceed, then re-enable MMIO */
        if (result == PCI_ERS_RESULT_CAN_RECOVER) {
                pr_info("EEH: Enable I/O for affected devices\n");
                rc = eeh_pci_enable(pe, EEH_OPT_THAW_MMIO);

                if (rc < 0) {
                        result = PCI_ERS_RESULT_DISCONNECT;
                } else if (rc) {
                        result = PCI_ERS_RESULT_NEED_RESET;
                } else {
                        pr_info("EEH: Notify device drivers to resume I/O\n");
                        eeh_pe_report("mmio_enabled", pe,
                                      eeh_report_mmio_enabled, &result);
                }
        }

        /* If all devices reported they can proceed, then re-enable DMA */
        if (result == PCI_ERS_RESULT_CAN_RECOVER) {
                pr_info("EEH: Enabled DMA for affected devices\n");
                rc = eeh_pci_enable(pe, EEH_OPT_THAW_DMA);

                if (rc < 0) {
                        result = PCI_ERS_RESULT_DISCONNECT;
                } else if (rc) {
                        result = PCI_ERS_RESULT_NEED_RESET;
                } else {
                        /*
                         * We didn't do PE reset for the case. The PE
                         * is still in frozen state. Clear it before
                         * resuming the PE.
                         */
                        eeh_pe_state_clear(pe, EEH_PE_ISOLATED, true);
                        result = PCI_ERS_RESULT_RECOVERED;
                }
        }

        /* If any device called out for a reset, then reset the slot */
        if (result == PCI_ERS_RESULT_NEED_RESET) {
                pr_info("EEH: Reset without hotplug activity\n");
                rc = eeh_reset_device(pe, bus, &rmv_data, true);
                if (rc) {
                        pr_warn("%s: Cannot reset, err=%d\n",
                                __func__, rc);
                        result = PCI_ERS_RESULT_DISCONNECT;
                } else {
                        result = PCI_ERS_RESULT_NONE;
                        eeh_set_channel_state(pe, pci_channel_io_normal);
                        eeh_set_irq_state(pe, true);
                        eeh_pe_report("slot_reset", pe, eeh_report_reset,
                                      &result);
                }
        }

        if ((result == PCI_ERS_RESULT_RECOVERED) ||
            (result == PCI_ERS_RESULT_NONE)) {
                /*
                 * For those hot removed VFs, we should add back them after PF
                 * get recovered properly.
                 */
                list_for_each_entry_safe(edev, tmp, &rmv_data.removed_vf_list,
                                         rmv_entry) {
                        eeh_add_virt_device(edev);
                        list_del(&edev->rmv_entry);
                }

                /* Tell all device drivers that they can resume operations */
                pr_info("EEH: Notify device driver to resume\n");
                eeh_set_channel_state(pe, pci_channel_io_normal);
                eeh_set_irq_state(pe, true);
                eeh_pe_report("resume", pe, eeh_report_resume, NULL);
                eeh_for_each_pe(pe, tmp_pe) {
                        eeh_pe_for_each_dev(tmp_pe, edev, tmp) {
                                edev->mode &= ~EEH_DEV_NO_HANDLER;
                                edev->in_error = false;
                        }
                }

                pr_info("EEH: Recovery successful.\n");
        } else  {
                /*
                 * About 90% of all real-life EEH failures in the field
                 * are due to poorly seated PCI cards. Only 10% or so are
                 * due to actual, failed cards.
                 */
                pr_err("EEH: Unable to recover from failure from PHB#%x-PE#%x.\n"
                       "Please try reseating or replacing it\n",
                        pe->phb->global_number, pe->addr);

                eeh_slot_error_detail(pe, EEH_LOG_PERM);

                /* Notify all devices that they're about to go down. */
                eeh_set_channel_state(pe, pci_channel_io_perm_failure);
                eeh_set_irq_state(pe, false);
                eeh_pe_report("error_detected(permanent failure)", pe,
                              eeh_report_failure, NULL);

                /* Mark the PE to be removed permanently */
                eeh_pe_state_mark(pe, EEH_PE_REMOVED);

                /*
                 * Shut down the device drivers for good. We mark
                 * all removed devices correctly to avoid access
                 * the their PCI config any more.
                 */
                if (pe->type & EEH_PE_VF) {
                        eeh_pe_dev_traverse(pe, eeh_rmv_device, NULL);
                        eeh_pe_dev_mode_mark(pe, EEH_DEV_REMOVED);
                } else {
                        eeh_pe_state_clear(pe, EEH_PE_PRI_BUS, true);
                        eeh_pe_dev_mode_mark(pe, EEH_DEV_REMOVED);

                        pci_lock_rescan_remove();
                        pci_hp_remove_devices(bus);
                        pci_unlock_rescan_remove();
                        /* The passed PE should no longer be used */
                        return;
                }
        }

out:
        /*
         * Clean up any PEs without devices. While marked as EEH_PE_RECOVERYING
         * we don't want to modify the PE tree structure so we do it here.
         */
        eeh_pe_cleanup(pe);

        /* clear the slot attention LED for all recovered devices */
        eeh_for_each_pe(pe, tmp_pe)
                eeh_pe_for_each_dev(tmp_pe, edev, tmp)
                        eeh_clear_slot_attention(edev->pdev);

        eeh_pe_state_clear(pe, EEH_PE_RECOVERING, true);
}

/**
 * eeh_handle_special_event - Handle EEH events without a specific failing PE
 *
 * Called when an EEH event is detected but can't be narrowed down to a
 * specific PE.  Iterates through possible failures and handles them as
 * necessary.
 */
void eeh_handle_special_event(void)
{
        struct eeh_pe *pe, *phb_pe, *tmp_pe;
        struct eeh_dev *edev, *tmp_edev;
        struct pci_bus *bus;
        struct pci_controller *hose;
        unsigned long flags;
        int rc;


        do {
                rc = eeh_ops->next_error(&pe);

                switch (rc) {
                case EEH_NEXT_ERR_DEAD_IOC:
                        /* Mark all PHBs in dead state */
                        eeh_serialize_lock(&flags);

                        /* Purge all events */
                        eeh_remove_event(NULL, true);

                        list_for_each_entry(hose, &hose_list, list_node) {
                                phb_pe = eeh_phb_pe_get(hose);
                                if (!phb_pe) continue;

                                eeh_pe_mark_isolated(phb_pe);
                        }

                        eeh_serialize_unlock(flags);

                        break;
                case EEH_NEXT_ERR_FROZEN_PE:
                case EEH_NEXT_ERR_FENCED_PHB:
                case EEH_NEXT_ERR_DEAD_PHB:
                        /* Mark the PE in fenced state */
                        eeh_serialize_lock(&flags);

                        /* Purge all events of the PHB */
                        eeh_remove_event(pe, true);

                        if (rc != EEH_NEXT_ERR_DEAD_PHB)
                                eeh_pe_state_mark(pe, EEH_PE_RECOVERING);
                        eeh_pe_mark_isolated(pe);

                        eeh_serialize_unlock(flags);

                        break;
                case EEH_NEXT_ERR_NONE:
                        return;
                default:
                        pr_warn("%s: Invalid value %d from next_error()\n",
                                __func__, rc);
                        return;
                }

                /*
                 * For fenced PHB and frozen PE, it's handled as normal
                 * event. We have to remove the affected PHBs for dead
                 * PHB and IOC
                 */
                if (rc == EEH_NEXT_ERR_FROZEN_PE ||
                    rc == EEH_NEXT_ERR_FENCED_PHB) {
                        eeh_pe_state_mark(pe, EEH_PE_RECOVERING);
                        eeh_handle_normal_event(pe);
                } else {
                        pci_lock_rescan_remove();
                        list_for_each_entry(hose, &hose_list, list_node) {
                                phb_pe = eeh_phb_pe_get(hose);
                                if (!phb_pe ||
                                    !(phb_pe->state & EEH_PE_ISOLATED) ||
                                    (phb_pe->state & EEH_PE_RECOVERING))
                                        continue;

                                eeh_for_each_pe(pe, tmp_pe)
                                        eeh_pe_for_each_dev(tmp_pe, edev, tmp_edev)
                                                edev->mode &= ~EEH_DEV_NO_HANDLER;

                                /* Notify all devices to be down */
                                eeh_pe_state_clear(pe, EEH_PE_PRI_BUS, true);
                                eeh_set_channel_state(pe, pci_channel_io_perm_failure);
                                eeh_pe_report(
                                        "error_detected(permanent failure)", pe,
                                        eeh_report_failure, NULL);
                                bus = eeh_pe_bus_get(phb_pe);
                                if (!bus) {
                                        pr_err("%s: Cannot find PCI bus for "
                                               "PHB#%x-PE#%x\n",
                                               __func__,
                                               pe->phb->global_number,
                                               pe->addr);
                                        break;
                                }
                                pci_hp_remove_devices(bus);
                        }
                        pci_unlock_rescan_remove();
                }

                /*
                 * If we have detected dead IOC, we needn't proceed
                 * any more since all PHBs would have been removed
                 */
                if (rc == EEH_NEXT_ERR_DEAD_IOC)
                        break;
        } while (rc != EEH_NEXT_ERR_NONE);
}