// SPDX-License-Identifier: GPL-2.0+
/*
 * PCI Hotplug Driver for PowerPC PowerNV platform.
 *
 * Copyright Gavin Shan, IBM Corporation 2016.
 * Copyright (C) 2025 Raptor Engineering, LLC
 * Copyright (C) 2025 Raptor Computing Systems, LLC
 */

#include <linux/bitfield.h>
#include <linux/libfdt.h>
#include <linux/module.h>
#include <linux/pci.h>
#include <linux/delay.h>
#include <linux/pci_hotplug.h>
#include <linux/of_fdt.h>

#include <asm/opal.h>
#include <asm/pnv-pci.h>
#include <asm/ppc-pci.h>

#define DRIVER_VERSION  "0.1"
#define DRIVER_AUTHOR   "Gavin Shan, IBM Corporation"
#define DRIVER_DESC     "PowerPC PowerNV PCI Hotplug Driver"

#define SLOT_WARN(sl, x...) \
        ((sl)->pdev ? pci_warn((sl)->pdev, x) : dev_warn(&(sl)->bus->dev, x))

struct pnv_php_event {
        bool                    added;
        struct pnv_php_slot     *php_slot;
        struct work_struct      work;
};

static LIST_HEAD(pnv_php_slot_list);
static DEFINE_SPINLOCK(pnv_php_lock);

static void pnv_php_register(struct device_node *dn);
static void pnv_php_unregister_one(struct device_node *dn);
static void pnv_php_unregister(struct device_node *dn);

static void pnv_php_enable_irq(struct pnv_php_slot *php_slot);

static void pnv_php_disable_irq(struct pnv_php_slot *php_slot,
                                bool disable_device, bool disable_msi)
{
        struct pci_dev *pdev = php_slot->pdev;
        u16 ctrl;

        if (php_slot->irq > 0) {
                pcie_capability_read_word(pdev, PCI_EXP_SLTCTL, &ctrl);
                ctrl &= ~(PCI_EXP_SLTCTL_HPIE |
                          PCI_EXP_SLTCTL_PDCE |
                          PCI_EXP_SLTCTL_DLLSCE);
                pcie_capability_write_word(pdev, PCI_EXP_SLTCTL, ctrl);

                free_irq(php_slot->irq, php_slot);
                php_slot->irq = 0;
        }

        if (disable_device || disable_msi) {
                if (pdev->msix_enabled)
                        pci_disable_msix(pdev);
                else if (pdev->msi_enabled)
                        pci_disable_msi(pdev);
        }

        if (disable_device)
                pci_disable_device(pdev);
}

static void pnv_php_free_slot(struct kref *kref)
{
        struct pnv_php_slot *php_slot = container_of(kref,
                                        struct pnv_php_slot, kref);

        WARN_ON(!list_empty(&php_slot->children));
        pnv_php_disable_irq(php_slot, false, false);
        destroy_workqueue(php_slot->wq);
        kfree(php_slot->name);
        kfree(php_slot);
}

static inline void pnv_php_put_slot(struct pnv_php_slot *php_slot)
{

        if (!php_slot)
                return;

        kref_put(&php_slot->kref, pnv_php_free_slot);
}

static struct pnv_php_slot *pnv_php_match(struct device_node *dn,
                                          struct pnv_php_slot *php_slot)
{
        struct pnv_php_slot *target, *tmp;

        if (php_slot->dn == dn) {
                kref_get(&php_slot->kref);
                return php_slot;
        }

        list_for_each_entry(tmp, &php_slot->children, link) {
                target = pnv_php_match(dn, tmp);
                if (target)
                        return target;
        }

        return NULL;
}

struct pnv_php_slot *pnv_php_find_slot(struct device_node *dn)
{
        struct pnv_php_slot *php_slot, *tmp;
        unsigned long flags;

        spin_lock_irqsave(&pnv_php_lock, flags);
        list_for_each_entry(tmp, &pnv_php_slot_list, link) {
                php_slot = pnv_php_match(dn, tmp);
                if (php_slot) {
                        spin_unlock_irqrestore(&pnv_php_lock, flags);
                        return php_slot;
                }
        }
        spin_unlock_irqrestore(&pnv_php_lock, flags);

        return NULL;
}
EXPORT_SYMBOL_GPL(pnv_php_find_slot);

/*
 * Remove pdn for all children of the indicated device node.
 * The function should remove pdn in a depth-first manner.
 */
static void pnv_php_rmv_pdns(struct device_node *dn)
{
        struct device_node *child;

        for_each_child_of_node(dn, child) {
                pnv_php_rmv_pdns(child);

                pci_remove_device_node_info(child);
        }
}

/*
 * Detach all child nodes of the indicated device nodes. The
 * function should handle device nodes in depth-first manner.
 *
 * We should not invoke of_node_release() as the memory for
 * individual device node is part of large memory block. The
 * large block is allocated from memblock (system bootup) or
 * kmalloc() when unflattening the device tree by OF changeset.
 * We can not free the large block allocated from memblock. For
 * later case, it should be released at once.
 */
static void pnv_php_detach_device_nodes(struct device_node *parent)
{
        struct device_node *dn;

        for_each_child_of_node(parent, dn) {
                pnv_php_detach_device_nodes(dn);

                of_node_put(dn);
                of_detach_node(dn);
        }
}

static void pnv_php_rmv_devtree(struct pnv_php_slot *php_slot)
{
        pnv_php_rmv_pdns(php_slot->dn);

        /*
         * Decrease the refcount if the device nodes were created
         * through OF changeset before detaching them.
         */
        if (php_slot->fdt)
                of_changeset_destroy(&php_slot->ocs);
        pnv_php_detach_device_nodes(php_slot->dn);

        if (php_slot->fdt) {
                kfree(php_slot->dt);
                kfree(php_slot->fdt);
                php_slot->dt        = NULL;
                php_slot->dn->child = NULL;
                php_slot->fdt       = NULL;
        }
}

/*
 * As the nodes in OF changeset are applied in reverse order, we
 * need revert the nodes in advance so that we have correct node
 * order after the changeset is applied.
 */
static void pnv_php_reverse_nodes(struct device_node *parent)
{
        struct device_node *child, *next;

        /* In-depth first */
        for_each_child_of_node(parent, child)
                pnv_php_reverse_nodes(child);

        /* Reverse the nodes in the child list */
        child = parent->child;
        parent->child = NULL;
        while (child) {
                next = child->sibling;

                child->sibling = parent->child;
                parent->child = child;
                child = next;
        }
}

static int pnv_php_populate_changeset(struct of_changeset *ocs,
                                      struct device_node *dn)
{
        int ret;

        for_each_child_of_node_scoped(dn, child) {
                ret = of_changeset_attach_node(ocs, child);
                if (ret)
                        return ret;

                ret = pnv_php_populate_changeset(ocs, child);
                if (ret)
                        return ret;
        }

        return 0;
}

static void *pnv_php_add_one_pdn(struct device_node *dn, void *data)
{
        struct pci_controller *hose = (struct pci_controller *)data;
        struct pci_dn *pdn;

        pdn = pci_add_device_node_info(hose, dn);
        if (!pdn)
                return ERR_PTR(-ENOMEM);

        return NULL;
}

static void pnv_php_add_pdns(struct pnv_php_slot *slot)
{
        struct pci_controller *hose = pci_bus_to_host(slot->bus);

        pci_traverse_device_nodes(slot->dn, pnv_php_add_one_pdn, hose);
}

static int pnv_php_add_devtree(struct pnv_php_slot *php_slot)
{
        void *fdt, *fdt1, *dt;
        int ret;

        /* We don't know the FDT blob size. We try to get it through
         * maximal memory chunk and then copy it to another chunk that
         * fits the real size.
         */
        fdt1 = kzalloc(0x10000, GFP_KERNEL);
        if (!fdt1) {
                ret = -ENOMEM;
                goto out;
        }

        ret = pnv_pci_get_device_tree(php_slot->dn->phandle, fdt1, 0x10000);
        if (ret) {
                SLOT_WARN(php_slot, "Error %d getting FDT blob\n", ret);
                goto free_fdt1;
        }

        fdt = kmemdup(fdt1, fdt_totalsize(fdt1), GFP_KERNEL);
        if (!fdt) {
                ret = -ENOMEM;
                goto free_fdt1;
        }

        /* Unflatten device tree blob */
        dt = of_fdt_unflatten_tree(fdt, php_slot->dn, NULL);
        if (!dt) {
                ret = -EINVAL;
                SLOT_WARN(php_slot, "Cannot unflatten FDT\n");
                goto free_fdt;
        }

        /* Initialize and apply the changeset */
        of_changeset_init(&php_slot->ocs);
        pnv_php_reverse_nodes(php_slot->dn);
        ret = pnv_php_populate_changeset(&php_slot->ocs, php_slot->dn);
        if (ret) {
                pnv_php_reverse_nodes(php_slot->dn);
                SLOT_WARN(php_slot, "Error %d populating changeset\n",
                          ret);
                goto free_dt;
        }

        php_slot->dn->child = NULL;
        ret = of_changeset_apply(&php_slot->ocs);
        if (ret) {
                SLOT_WARN(php_slot, "Error %d applying changeset\n", ret);
                goto destroy_changeset;
        }

        /* Add device node firmware data */
        pnv_php_add_pdns(php_slot);
        php_slot->fdt = fdt;
        php_slot->dt  = dt;
        kfree(fdt1);
        goto out;

destroy_changeset:
        of_changeset_destroy(&php_slot->ocs);
free_dt:
        kfree(dt);
        php_slot->dn->child = NULL;
free_fdt:
        kfree(fdt);
free_fdt1:
        kfree(fdt1);
out:
        return ret;
}

static inline struct pnv_php_slot *to_pnv_php_slot(struct hotplug_slot *slot)
{
        return container_of(slot, struct pnv_php_slot, slot);
}

int pnv_php_set_slot_power_state(struct hotplug_slot *slot,
                                 uint8_t state)
{
        struct pnv_php_slot *php_slot = to_pnv_php_slot(slot);
        struct opal_msg msg;
        int ret;

        ret = pnv_pci_set_power_state(php_slot->id, state, &msg);
        if (ret > 0) {
                if (be64_to_cpu(msg.params[1]) != php_slot->dn->phandle ||
                    be64_to_cpu(msg.params[2]) != state) {
                        SLOT_WARN(php_slot, "Wrong msg (%lld, %lld, %lld)\n",
                                  be64_to_cpu(msg.params[1]),
                                  be64_to_cpu(msg.params[2]),
                                  be64_to_cpu(msg.params[3]));
                        return -ENOMSG;
                }
                if (be64_to_cpu(msg.params[3]) != OPAL_SUCCESS) {
                        ret = -ENODEV;
                        goto error;
                }
        } else if (ret < 0) {
                goto error;
        }

        if (state == OPAL_PCI_SLOT_POWER_OFF || state == OPAL_PCI_SLOT_OFFLINE)
                pnv_php_rmv_devtree(php_slot);
        else
                ret = pnv_php_add_devtree(php_slot);

        return ret;

error:
        SLOT_WARN(php_slot, "Error %d powering %s\n",
                  ret, (state == OPAL_PCI_SLOT_POWER_ON) ? "on" : "off");
        return ret;
}
EXPORT_SYMBOL_GPL(pnv_php_set_slot_power_state);

static int pnv_php_get_power_state(struct hotplug_slot *slot, u8 *state)
{
        struct pnv_php_slot *php_slot = to_pnv_php_slot(slot);
        uint8_t power_state = OPAL_PCI_SLOT_POWER_ON;
        int ret;

        /*
         * Retrieve power status from firmware. If we fail
         * getting that, the power status fails back to
         * be on.
         */
        ret = pnv_pci_get_power_state(php_slot->id, &power_state);
        if (ret) {
                SLOT_WARN(php_slot, "Error %d getting power status\n",
                          ret);
        } else {
                *state = power_state;
        }

        return 0;
}

static int pcie_check_link_active(struct pci_dev *pdev)
{
        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);

        return ret;
}

static int pnv_php_get_adapter_state(struct hotplug_slot *slot, u8 *state)
{
        struct pnv_php_slot *php_slot = to_pnv_php_slot(slot);
        uint8_t presence = OPAL_PCI_SLOT_EMPTY;
        int ret;

        /*
         * Retrieve presence status from firmware. If we can't
         * get that, it will fail back to be empty.
         */
        ret = pnv_pci_get_presence_state(php_slot->id, &presence);
        if (ret >= 0) {
                if (pci_pcie_type(php_slot->pdev) == PCI_EXP_TYPE_DOWNSTREAM &&
                        presence == OPAL_PCI_SLOT_EMPTY) {
                        /*
                         * Similar to pciehp_hpc, check whether the Link Active
                         * bit is set to account for broken downstream bridges
                         * that don't properly assert Presence Detect State, as
                         * was observed on the Microsemi Switchtec PM8533 PFX
                         * [11f8:8533].
                         */
                        if (pcie_check_link_active(php_slot->pdev) > 0)
                                presence = OPAL_PCI_SLOT_PRESENT;
                }

                *state = presence;
                ret = 0;
        } else {
                SLOT_WARN(php_slot, "Error %d getting presence\n", ret);
        }

        return ret;
}

static int pnv_php_get_raw_indicator_status(struct hotplug_slot *slot, u8 *state)
{
        struct pnv_php_slot *php_slot = to_pnv_php_slot(slot);
        struct pci_dev *bridge = php_slot->pdev;
        u16 status;

        pcie_capability_read_word(bridge, PCI_EXP_SLTCTL, &status);
        *state = (status & (PCI_EXP_SLTCTL_AIC | PCI_EXP_SLTCTL_PIC)) >> 6;
        return 0;
}


static int pnv_php_get_attention_state(struct hotplug_slot *slot, u8 *state)
{
        struct pnv_php_slot *php_slot = to_pnv_php_slot(slot);

        pnv_php_get_raw_indicator_status(slot, &php_slot->attention_state);
        *state = php_slot->attention_state;
        return 0;
}

static int pnv_php_set_attention_state(struct hotplug_slot *slot, u8 state)
{
        struct pnv_php_slot *php_slot = to_pnv_php_slot(slot);
        struct pci_dev *bridge = php_slot->pdev;
        u16 new, mask;

        php_slot->attention_state = state;
        if (!bridge)
                return 0;

        mask = PCI_EXP_SLTCTL_AIC;

        if (state)
                new = FIELD_PREP(PCI_EXP_SLTCTL_AIC, state);
        else
                new = PCI_EXP_SLTCTL_ATTN_IND_OFF;

        pcie_capability_clear_and_set_word(bridge, PCI_EXP_SLTCTL, mask, new);

        return 0;
}

static int pnv_php_activate_slot(struct pnv_php_slot *php_slot,
                                 struct hotplug_slot *slot)
{
        int ret, i;

        /*
         * Issue initial slot activation command to firmware
         *
         * Firmware will power slot on, attempt to train the link, and
         * discover any downstream devices. If this process fails, firmware
         * will return an error code and an invalid device tree. Failure
         * can be caused for multiple reasons, including a faulty
         * downstream device, poor connection to the downstream device, or
         * a previously latched PHB fence.  On failure, issue fundamental
         * reset up to three times before aborting.
         */
        ret = pnv_php_set_slot_power_state(slot, OPAL_PCI_SLOT_POWER_ON);
        if (ret) {
                SLOT_WARN(
                        php_slot,
                        "PCI slot activation failed with error code %d, possible frozen PHB",
                        ret);
                SLOT_WARN(
                        php_slot,
                        "Attempting complete PHB reset before retrying slot activation\n");
                for (i = 0; i < 3; i++) {
                        /*
                         * Slot activation failed, PHB may be fenced from a
                         * prior device failure.
                         *
                         * Use the OPAL fundamental reset call to both try a
                         * device reset and clear any potentially active PHB
                         * fence / freeze.
                         */
                        SLOT_WARN(php_slot, "Try %d...\n", i + 1);
                        pci_set_pcie_reset_state(php_slot->pdev,
                                                 pcie_warm_reset);
                        msleep(250);
                        pci_set_pcie_reset_state(php_slot->pdev,
                                                 pcie_deassert_reset);

                        ret = pnv_php_set_slot_power_state(
                                slot, OPAL_PCI_SLOT_POWER_ON);
                        if (!ret)
                                break;
                }

                if (i >= 3)
                        SLOT_WARN(php_slot,
                                  "Failed to bring slot online, aborting!\n");
        }

        return ret;
}

static int pnv_php_enable(struct pnv_php_slot *php_slot, bool rescan)
{
        struct hotplug_slot *slot = &php_slot->slot;
        uint8_t presence = OPAL_PCI_SLOT_EMPTY;
        uint8_t power_status = OPAL_PCI_SLOT_POWER_ON;
        int ret;

        /* Check if the slot has been configured */
        if (php_slot->state != PNV_PHP_STATE_REGISTERED)
                return 0;

        /* Retrieve slot presence status */
        ret = pnv_php_get_adapter_state(slot, &presence);
        if (ret)
                return ret;

        /*
         * Proceed if there have nothing behind the slot. However,
         * we should leave the slot in registered state at the
         * beginning. Otherwise, the PCI devices inserted afterwards
         * won't be probed and populated.
         */
        if (presence == OPAL_PCI_SLOT_EMPTY) {
                if (!php_slot->power_state_check) {
                        php_slot->power_state_check = true;

                        return 0;
                }

                goto scan;
        }

        /*
         * If the power supply to the slot is off, we can't detect
         * adapter presence state. That means we have to turn the
         * slot on before going to probe slot's presence state.
         *
         * On the first time, we don't change the power status to
         * boost system boot with assumption that the firmware
         * supplies consistent slot power status: empty slot always
         * has its power off and non-empty slot has its power on.
         */
        if (!php_slot->power_state_check) {
                php_slot->power_state_check = true;

                ret = pnv_php_get_power_state(slot, &power_status);
                if (ret)
                        return ret;

                if (power_status != OPAL_PCI_SLOT_POWER_ON)
                        return 0;
        }

        /* Check the power status. Scan the slot if it is already on */
        ret = pnv_php_get_power_state(slot, &power_status);
        if (ret)
                return ret;

        if (power_status == OPAL_PCI_SLOT_POWER_ON)
                goto scan;

        /* Power is off, turn it on and then scan the slot */
        ret = pnv_php_activate_slot(php_slot, slot);
        if (ret)
                return ret;

scan:
        if (presence == OPAL_PCI_SLOT_PRESENT) {
                if (rescan) {
                        pci_lock_rescan_remove();
                        pci_hp_add_devices(php_slot->bus);
                        pci_unlock_rescan_remove();
                }

                /* Rescan for child hotpluggable slots */
                php_slot->state = PNV_PHP_STATE_POPULATED;
                if (rescan)
                        pnv_php_register(php_slot->dn);
        } else {
                php_slot->state = PNV_PHP_STATE_POPULATED;
        }

        return 0;
}

static int pnv_php_reset_slot(struct hotplug_slot *slot, bool probe)
{
        struct pnv_php_slot *php_slot = to_pnv_php_slot(slot);
        struct pci_dev *bridge = php_slot->pdev;
        uint16_t sts;

        /*
         * The CAPI folks want pnv_php to drive OpenCAPI slots
         * which don't have a bridge. Only claim to support
         * reset_slot() if we have a bridge device (for now...)
         */
        if (probe)
                return !bridge;

        /* mask our interrupt while resetting the bridge */
        if (php_slot->irq > 0)
                disable_irq(php_slot->irq);

        pci_bridge_secondary_bus_reset(bridge);

        /* clear any state changes that happened due to the reset */
        pcie_capability_read_word(php_slot->pdev, PCI_EXP_SLTSTA, &sts);
        sts &= (PCI_EXP_SLTSTA_PDC | PCI_EXP_SLTSTA_DLLSC);
        pcie_capability_write_word(php_slot->pdev, PCI_EXP_SLTSTA, sts);

        if (php_slot->irq > 0)
                enable_irq(php_slot->irq);

        return 0;
}

static int pnv_php_enable_slot(struct hotplug_slot *slot)
{
        struct pnv_php_slot *php_slot = to_pnv_php_slot(slot);
        u32 prop32;
        int ret;

        ret = pnv_php_enable(php_slot, true);
        if (ret)
                return ret;

        /* (Re-)enable interrupt if the slot supports surprise hotplug */
        ret = of_property_read_u32(php_slot->dn, "ibm,slot-surprise-pluggable",
                                   &prop32);
        if (!ret && prop32)
                pnv_php_enable_irq(php_slot);

        return 0;
}

/*
 * Disable any hotplug interrupts for all slots on the provided bus, as well as
 * all downstream slots in preparation for a hot unplug.
 */
static int pnv_php_disable_all_irqs(struct pci_bus *bus)
{
        struct pci_bus *child_bus;
        struct pci_slot *slot;

        /* First go down child buses */
        list_for_each_entry(child_bus, &bus->children, node)
                pnv_php_disable_all_irqs(child_bus);

        /* Disable IRQs for all pnv_php slots on this bus */
        list_for_each_entry(slot, &bus->slots, list) {
                struct pnv_php_slot *php_slot = to_pnv_php_slot(slot->hotplug);

                pnv_php_disable_irq(php_slot, false, true);
        }

        return 0;
}

/*
 * Disable any hotplug interrupts for all downstream slots on the provided
 * bus in preparation for a hot unplug.
 */
static int pnv_php_disable_all_downstream_irqs(struct pci_bus *bus)
{
        struct pci_bus *child_bus;

        /* Go down child buses, recursively deactivating their IRQs */
        list_for_each_entry(child_bus, &bus->children, node)
                pnv_php_disable_all_irqs(child_bus);

        return 0;
}

static int pnv_php_disable_slot(struct hotplug_slot *slot)
{
        struct pnv_php_slot *php_slot = to_pnv_php_slot(slot);
        int ret;

        /*
         * Allow to disable a slot already in the registered state to
         * cover cases where the slot couldn't be enabled and never
         * reached the populated state
         */
        if (php_slot->state != PNV_PHP_STATE_POPULATED &&
            php_slot->state != PNV_PHP_STATE_REGISTERED)
                return 0;

        /*
         * Free all IRQ resources from all child slots before remove.
         * Note that we do not disable the root slot IRQ here as that
         * would also deactivate the slot hot (re)plug interrupt!
         */
        pnv_php_disable_all_downstream_irqs(php_slot->bus);

        /* Remove all devices behind the slot */
        pci_lock_rescan_remove();
        pci_hp_remove_devices(php_slot->bus);
        pci_unlock_rescan_remove();

        /* Detach the child hotpluggable slots */
        pnv_php_unregister(php_slot->dn);

        /* Notify firmware and remove device nodes */
        ret = pnv_php_set_slot_power_state(slot, OPAL_PCI_SLOT_POWER_OFF);

        php_slot->state = PNV_PHP_STATE_REGISTERED;
        return ret;
}

static const struct hotplug_slot_ops php_slot_ops = {
        .get_power_status       = pnv_php_get_power_state,
        .get_adapter_status     = pnv_php_get_adapter_state,
        .get_attention_status   = pnv_php_get_attention_state,
        .set_attention_status   = pnv_php_set_attention_state,
        .enable_slot            = pnv_php_enable_slot,
        .disable_slot           = pnv_php_disable_slot,
        .reset_slot             = pnv_php_reset_slot,
};

static void pnv_php_release(struct pnv_php_slot *php_slot)
{
        unsigned long flags;

        /* Remove from global or child list */
        spin_lock_irqsave(&pnv_php_lock, flags);
        list_del(&php_slot->link);
        spin_unlock_irqrestore(&pnv_php_lock, flags);

        /* Detach from parent */
        pnv_php_put_slot(php_slot);
        pnv_php_put_slot(php_slot->parent);
}

static struct pnv_php_slot *pnv_php_alloc_slot(struct device_node *dn)
{
        struct pnv_php_slot *php_slot;
        struct pci_bus *bus;
        const char *label;
        uint64_t id;
        int ret;

        ret = of_property_read_string(dn, "ibm,slot-label", &label);
        if (ret)
                return NULL;

        if (pnv_pci_get_slot_id(dn, &id))
                return NULL;

        bus = pci_find_bus_by_node(dn);
        if (!bus)
                return NULL;

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

        php_slot->name = kstrdup(label, GFP_KERNEL);
        if (!php_slot->name) {
                kfree(php_slot);
                return NULL;
        }

        /* Allocate workqueue for this slot's interrupt handling */
        php_slot->wq = alloc_workqueue("pciehp-%s", WQ_PERCPU, 0, php_slot->name);
        if (!php_slot->wq) {
                SLOT_WARN(php_slot, "Cannot alloc workqueue\n");
                kfree(php_slot->name);
                kfree(php_slot);
                return NULL;
        }

        if (dn->child && PCI_DN(dn->child))
                php_slot->slot_no = PCI_SLOT(PCI_DN(dn->child)->devfn);
        else
                php_slot->slot_no = -1;   /* Placeholder slot */

        kref_init(&php_slot->kref);
        php_slot->state                 = PNV_PHP_STATE_INITIALIZED;
        php_slot->dn                    = dn;
        php_slot->pdev                  = bus->self;
        php_slot->bus                   = bus;
        php_slot->id                    = id;
        php_slot->power_state_check     = false;
        php_slot->slot.ops              = &php_slot_ops;

        INIT_LIST_HEAD(&php_slot->children);
        INIT_LIST_HEAD(&php_slot->link);

        return php_slot;
}

static int pnv_php_register_slot(struct pnv_php_slot *php_slot)
{
        struct pnv_php_slot *parent;
        struct device_node *dn = php_slot->dn;
        unsigned long flags;
        int ret;

        /* Check if the slot is registered or not */
        parent = pnv_php_find_slot(php_slot->dn);
        if (parent) {
                pnv_php_put_slot(parent);
                return -EEXIST;
        }

        /* Register PCI slot */
        ret = pci_hp_register(&php_slot->slot, php_slot->bus,
                              php_slot->slot_no, php_slot->name);
        if (ret) {
                SLOT_WARN(php_slot, "Error %d registering slot\n", ret);
                return ret;
        }

        /* Attach to the parent's child list or global list */
        while ((dn = of_get_parent(dn))) {
                if (!PCI_DN(dn)) {
                        of_node_put(dn);
                        break;
                }

                parent = pnv_php_find_slot(dn);
                if (parent) {
                        of_node_put(dn);
                        break;
                }

                of_node_put(dn);
        }

        spin_lock_irqsave(&pnv_php_lock, flags);
        php_slot->parent = parent;
        if (parent)
                list_add_tail(&php_slot->link, &parent->children);
        else
                list_add_tail(&php_slot->link, &pnv_php_slot_list);
        spin_unlock_irqrestore(&pnv_php_lock, flags);

        php_slot->state = PNV_PHP_STATE_REGISTERED;
        return 0;
}

static int pnv_php_enable_msix(struct pnv_php_slot *php_slot)
{
        struct pci_dev *pdev = php_slot->pdev;
        struct msix_entry entry;
        int nr_entries, ret;
        u16 pcie_flag;

        /* Get total number of MSIx entries */
        nr_entries = pci_msix_vec_count(pdev);
        if (nr_entries < 0)
                return nr_entries;

        /* Check hotplug MSIx entry is in range */
        pcie_capability_read_word(pdev, PCI_EXP_FLAGS, &pcie_flag);
        entry.entry = FIELD_GET(PCI_EXP_FLAGS_IRQ, pcie_flag);
        if (entry.entry >= nr_entries)
                return -ERANGE;

        /* Enable MSIx */
        ret = pci_enable_msix_exact(pdev, &entry, 1);
        if (ret) {
                SLOT_WARN(php_slot, "Error %d enabling MSIx\n", ret);
                return ret;
        }

        return entry.vector;
}

static void
pnv_php_detect_clear_suprise_removal_freeze(struct pnv_php_slot *php_slot)
{
        struct pci_dev *pdev = php_slot->pdev;
        struct eeh_dev *edev;
        struct eeh_pe *pe;
        int i, rc;

        /*
         * When a device is surprise removed from a downstream bridge slot,
         * the upstream bridge port can still end up frozen due to related EEH
         * events, which will in turn block the MSI interrupts for slot hotplug
         * detection.
         *
         * Detect and thaw any frozen upstream PE after slot deactivation.
         */
        edev = pci_dev_to_eeh_dev(pdev);
        pe = edev ? edev->pe : NULL;
        rc = eeh_pe_get_state(pe);
        if ((rc == -ENODEV) || (rc == -ENOENT)) {
                SLOT_WARN(
                        php_slot,
                        "Upstream bridge PE state unknown, hotplug detect may fail\n");
        } else {
                if (pe->state & EEH_PE_ISOLATED) {
                        SLOT_WARN(
                                php_slot,
                                "Upstream bridge PE %02x frozen, thawing...\n",
                                pe->addr);
                        for (i = 0; i < 3; i++)
                                if (!eeh_unfreeze_pe(pe))
                                        break;
                        if (i >= 3)
                                SLOT_WARN(
                                        php_slot,
                                        "Unable to thaw PE %02x, hotplug detect will fail!\n",
                                        pe->addr);
                        else
                                SLOT_WARN(php_slot,
                                          "PE %02x thawed successfully\n",
                                          pe->addr);
                }
        }
}

static void pnv_php_event_handler(struct work_struct *work)
{
        struct pnv_php_event *event =
                container_of(work, struct pnv_php_event, work);
        struct pnv_php_slot *php_slot = event->php_slot;

        if (event->added) {
                pnv_php_enable_slot(&php_slot->slot);
        } else {
                pnv_php_disable_slot(&php_slot->slot);
                pnv_php_detect_clear_suprise_removal_freeze(php_slot);
        }

        kfree(event);
}

static irqreturn_t pnv_php_interrupt(int irq, void *data)
{
        struct pnv_php_slot *php_slot = data;
        struct pci_dev *pchild, *pdev = php_slot->pdev;
        struct eeh_dev *edev;
        struct eeh_pe *pe;
        struct pnv_php_event *event;
        u16 sts, lsts;
        u8 presence;
        bool added;
        unsigned long flags;
        int ret;

        pcie_capability_read_word(pdev, PCI_EXP_SLTSTA, &sts);
        sts &= (PCI_EXP_SLTSTA_PDC | PCI_EXP_SLTSTA_DLLSC);
        pcie_capability_write_word(pdev, PCI_EXP_SLTSTA, sts);

        pci_dbg(pdev, "PCI slot [%s]: HP int! DLAct: %d, PresDet: %d\n",
                        php_slot->name,
                        !!(sts & PCI_EXP_SLTSTA_DLLSC),
                        !!(sts & PCI_EXP_SLTSTA_PDC));

        if (sts & PCI_EXP_SLTSTA_DLLSC) {
                pcie_capability_read_word(pdev, PCI_EXP_LNKSTA, &lsts);
                added = !!(lsts & PCI_EXP_LNKSTA_DLLLA);
        } else if (!(php_slot->flags & PNV_PHP_FLAG_BROKEN_PDC) &&
                   (sts & PCI_EXP_SLTSTA_PDC)) {
                ret = pnv_pci_get_presence_state(php_slot->id, &presence);
                if (ret) {
                        SLOT_WARN(php_slot,
                                  "PCI slot [%s] error %d getting presence (0x%04x), to retry the operation.\n",
                                  php_slot->name, ret, sts);
                        return IRQ_HANDLED;
                }

                added = !!(presence == OPAL_PCI_SLOT_PRESENT);
        } else {
                pci_dbg(pdev, "PCI slot [%s]: Spurious IRQ?\n", php_slot->name);
                return IRQ_NONE;
        }

        /* Freeze the removed PE to avoid unexpected error reporting */
        if (!added) {
                pchild = list_first_entry_or_null(&php_slot->bus->devices,
                                                  struct pci_dev, bus_list);
                edev = pchild ? pci_dev_to_eeh_dev(pchild) : NULL;
                pe = edev ? edev->pe : NULL;
                if (pe) {
                        eeh_serialize_lock(&flags);
                        eeh_pe_mark_isolated(pe);
                        eeh_serialize_unlock(flags);
                        eeh_pe_set_option(pe, EEH_OPT_FREEZE_PE);
                }
        }

        /*
         * The PE is left in frozen state if the event is missed. It's
         * fine as the PCI devices (PE) aren't functional any more.
         */
        event = kzalloc_obj(*event, GFP_ATOMIC);
        if (!event) {
                SLOT_WARN(php_slot,
                          "PCI slot [%s] missed hotplug event 0x%04x\n",
                          php_slot->name, sts);
                return IRQ_HANDLED;
        }

        pci_info(pdev, "PCI slot [%s] %s (IRQ: %d)\n",
                 php_slot->name, added ? "added" : "removed", irq);
        INIT_WORK(&event->work, pnv_php_event_handler);
        event->added = added;
        event->php_slot = php_slot;
        queue_work(php_slot->wq, &event->work);

        return IRQ_HANDLED;
}

static void pnv_php_init_irq(struct pnv_php_slot *php_slot, int irq)
{
        struct pci_dev *pdev = php_slot->pdev;
        u32 broken_pdc = 0;
        u16 sts, ctrl;
        int ret;

        /* Check PDC (Presence Detection Change) is broken or not */
        ret = of_property_read_u32(php_slot->dn, "ibm,slot-broken-pdc",
                                   &broken_pdc);
        if (!ret && broken_pdc)
                php_slot->flags |= PNV_PHP_FLAG_BROKEN_PDC;

        /* Clear pending interrupts */
        pcie_capability_read_word(pdev, PCI_EXP_SLTSTA, &sts);
        if (php_slot->flags & PNV_PHP_FLAG_BROKEN_PDC)
                sts |= PCI_EXP_SLTSTA_DLLSC;
        else
                sts |= (PCI_EXP_SLTSTA_PDC | PCI_EXP_SLTSTA_DLLSC);
        pcie_capability_write_word(pdev, PCI_EXP_SLTSTA, sts);

        /* Request the interrupt */
        ret = request_irq(irq, pnv_php_interrupt, IRQF_SHARED,
                          php_slot->name, php_slot);
        if (ret) {
                pnv_php_disable_irq(php_slot, true, true);
                SLOT_WARN(php_slot, "Error %d enabling IRQ %d\n", ret, irq);
                return;
        }

        /* Enable the interrupts */
        pcie_capability_read_word(pdev, PCI_EXP_SLTCTL, &ctrl);
        if (php_slot->flags & PNV_PHP_FLAG_BROKEN_PDC) {
                ctrl &= ~PCI_EXP_SLTCTL_PDCE;
                ctrl |= (PCI_EXP_SLTCTL_HPIE |
                         PCI_EXP_SLTCTL_DLLSCE);
        } else {
                ctrl |= (PCI_EXP_SLTCTL_HPIE |
                         PCI_EXP_SLTCTL_PDCE |
                         PCI_EXP_SLTCTL_DLLSCE);
        }
        pcie_capability_write_word(pdev, PCI_EXP_SLTCTL, ctrl);

        /* The interrupt is initialized successfully when @irq is valid */
        php_slot->irq = irq;
}

static void pnv_php_enable_irq(struct pnv_php_slot *php_slot)
{
        struct pci_dev *pdev = php_slot->pdev;
        int irq, ret;

        /*
         * The MSI/MSIx interrupt might have been occupied by other
         * drivers. Don't populate the surprise hotplug capability
         * in that case.
         */
        if (pci_dev_msi_enabled(pdev))
                return;

        ret = pci_enable_device(pdev);
        if (ret) {
                SLOT_WARN(php_slot, "Error %d enabling device\n", ret);
                return;
        }

        pci_set_master(pdev);

        /* Enable MSIx interrupt */
        irq = pnv_php_enable_msix(php_slot);
        if (irq > 0) {
                pnv_php_init_irq(php_slot, irq);
                return;
        }

        /*
         * Use MSI if MSIx doesn't work. Fail back to legacy INTx
         * if MSI doesn't work either
         */
        ret = pci_enable_msi(pdev);
        if (!ret || pdev->irq) {
                irq = pdev->irq;
                pnv_php_init_irq(php_slot, irq);
        }
}

static int pnv_php_register_one(struct device_node *dn)
{
        struct pnv_php_slot *php_slot;
        u32 prop32;
        int ret;

        /* Check if it's hotpluggable slot */
        ret = of_property_read_u32(dn, "ibm,slot-pluggable", &prop32);
        if (ret || !prop32)
                return -ENXIO;

        ret = of_property_read_u32(dn, "ibm,reset-by-firmware", &prop32);
        if (ret || !prop32)
                return -ENXIO;

        php_slot = pnv_php_alloc_slot(dn);
        if (!php_slot)
                return -ENODEV;

        ret = pnv_php_register_slot(php_slot);
        if (ret)
                goto free_slot;

        ret = pnv_php_enable(php_slot, false);
        if (ret)
                goto unregister_slot;

        /* Enable interrupt if the slot supports surprise hotplug */
        ret = of_property_read_u32(dn, "ibm,slot-surprise-pluggable", &prop32);
        if (!ret && prop32)
                pnv_php_enable_irq(php_slot);

        return 0;

unregister_slot:
        pnv_php_unregister_one(php_slot->dn);
free_slot:
        pnv_php_put_slot(php_slot);
        return ret;
}

static void pnv_php_register(struct device_node *dn)
{
        struct device_node *child;

        /*
         * The parent slots should be registered before their
         * child slots.
         */
        for_each_child_of_node(dn, child) {
                pnv_php_register_one(child);
                pnv_php_register(child);
        }
}

static void pnv_php_unregister_one(struct device_node *dn)
{
        struct pnv_php_slot *php_slot;

        php_slot = pnv_php_find_slot(dn);
        if (!php_slot)
                return;

        php_slot->state = PNV_PHP_STATE_OFFLINE;
        pci_hp_deregister(&php_slot->slot);
        pnv_php_release(php_slot);
        pnv_php_put_slot(php_slot);
}

static void pnv_php_unregister(struct device_node *dn)
{
        struct device_node *child;

        /* The child slots should go before their parent slots */
        for_each_child_of_node(dn, child) {
                pnv_php_unregister(child);
                pnv_php_unregister_one(child);
        }
}

static int __init pnv_php_init(void)
{
        struct device_node *dn;

        pr_info(DRIVER_DESC " version: " DRIVER_VERSION "\n");
        for_each_compatible_node(dn, NULL, "ibm,ioda2-phb")
                pnv_php_register(dn);

        for_each_compatible_node(dn, NULL, "ibm,ioda3-phb")
                pnv_php_register(dn);

        for_each_compatible_node(dn, NULL, "ibm,ioda2-npu2-opencapi-phb")
                pnv_php_register_one(dn); /* slot directly under the PHB */
        return 0;
}

static void __exit pnv_php_exit(void)
{
        struct device_node *dn;

        for_each_compatible_node(dn, NULL, "ibm,ioda2-phb")
                pnv_php_unregister(dn);

        for_each_compatible_node(dn, NULL, "ibm,ioda3-phb")
                pnv_php_unregister(dn);

        for_each_compatible_node(dn, NULL, "ibm,ioda2-npu2-opencapi-phb")
                pnv_php_unregister_one(dn); /* slot directly under the PHB */
}

module_init(pnv_php_init);
module_exit(pnv_php_exit);

MODULE_VERSION(DRIVER_VERSION);
MODULE_LICENSE("GPL v2");
MODULE_AUTHOR(DRIVER_AUTHOR);
MODULE_DESCRIPTION(DRIVER_DESC);