// 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)
{
	struct device_node *child;
	int ret = 0;

	for_each_child_of_node(dn, child) {
		ret = of_changeset_attach_node(ocs, child);
		if (ret) {
			of_node_put(child);
			break;
		}

		ret = pnv_php_populate_changeset(ocs, child);
		if (ret) {
			of_node_put(child);
			break;
		}
	}

	return ret;
}

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(sizeof(*php_slot), GFP_KERNEL);
	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", 0, 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(sizeof(*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);