PCI/hotplug: PowerPC PowerNV PCI hotplug driver

This adds standalone driver to support PCI hotplug for PowerPC PowerNV
platform that runs on top of skiboot firmware. The firmware identifies
hotpluggable slots and marked their device tree node with proper
"ibm,slot-pluggable" and "ibm,reset-by-firmware". The driver scans
device tree nodes to create/register PCI hotplug slot accordingly.

The PCI slots are organized in fashion of tree, which means one
PCI slot might have parent PCI slot and parent PCI slot possibly
contains multiple child PCI slots. At the plugging time, the parent
PCI slot is populated before its children. The child PCI slots are
removed before their parent PCI slot can be removed from the system.

If the skiboot firmware doesn't support slot status retrieval, the PCI
slot device node shouldn't have property "ibm,reset-by-firmware". In
that case, none of valid PCI slots will be detected from device tree.
The skiboot firmware doesn't export the capability to access attention
LEDs yet and it's something for TBD.

Signed-off-by: Gavin Shan <[e-mail]>
Acked-by: Bjorn Helgaas <[e-mail]>
Signed-off-by: Michael Ellerman <[e-mail]>

MAINTAINERS

···
 F:	drivers/crypto/vmx/
 F:	drivers/net/ethernet/ibm/ibmveth.*
 F:	drivers/net/ethernet/ibm/ibmvnic.*
+F:	drivers/pci/hotplug/pnv_php.c
 F:	drivers/pci/hotplug/rpa*
 F:	drivers/scsi/ibmvscsi/
 N:	opal

drivers/pci/hotplug/Kconfig

···
 
 	  When in doubt, say N.
 
+config HOTPLUG_PCI_POWERNV
+	tristate "PowerPC PowerNV PCI Hotplug driver"
+	depends on PPC_POWERNV && EEH
+	select OF_DYNAMIC
+	help
+	  Say Y here if you run PowerPC PowerNV platform that supports
+	  PCI Hotplug
+
+	  To compile this driver as a module, choose M here: the
+	  module will be called pnv-php.
+
+	  When in doubt, say N.
+
 config HOTPLUG_PCI_RPA
 	tristate "RPA PCI Hotplug driver"
 	depends on PPC_PSERIES && EEH

drivers/pci/hotplug/Makefile

···
 obj-$(CONFIG_HOTPLUG_PCI_CPCI_ZT5550)	+= cpcihp_zt5550.o
 obj-$(CONFIG_HOTPLUG_PCI_CPCI_GENERIC)	+= cpcihp_generic.o
 obj-$(CONFIG_HOTPLUG_PCI_SHPC)		+= shpchp.o
+obj-$(CONFIG_HOTPLUG_PCI_POWERNV)	+= pnv-php.o
 obj-$(CONFIG_HOTPLUG_PCI_RPA)		+= rpaphp.o
 obj-$(CONFIG_HOTPLUG_PCI_RPA_DLPAR)	+= rpadlpar_io.o
 obj-$(CONFIG_HOTPLUG_PCI_SGI)		+= sgi_hotplug.o
···
 
 acpiphp-objs		:=	acpiphp_core.o	\
 				acpiphp_glue.o
+
+pnv-php-objs		:=	pnv_php.o
 
 rpaphp-objs		:=	rpaphp_core.o	\
 				rpaphp_pci.o	\

drivers/pci/hotplug/pnv_php.c

···
+/*
+ * PCI Hotplug Driver for PowerPC PowerNV platform.
+ *
+ * Copyright Gavin Shan, IBM Corporation 2016.
+ *
+ * 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.
+ */
+
+#include <linux/libfdt.h>
+#include <linux/module.h>
+#include <linux/pci.h>
+#include <linux/pci_hotplug.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"
+
+struct pnv_php_slot {
+	struct hotplug_slot		slot;
+	struct hotplug_slot_info	slot_info;
+	uint64_t			id;
+	char				*name;
+	int				slot_no;
+	struct kref			kref;
+#define PNV_PHP_STATE_INITIALIZED	0
+#define PNV_PHP_STATE_REGISTERED	1
+#define PNV_PHP_STATE_POPULATED		2
+#define PNV_PHP_STATE_OFFLINE		3
+	int				state;
+	struct device_node		*dn;
+	struct pci_dev			*pdev;
+	struct pci_bus			*bus;
+	bool				power_state_check;
+	void				*fdt;
+	void				*dt;
+	struct of_changeset		ocs;
+	struct pnv_php_slot		*parent;
+	struct list_head		children;
+	struct list_head		link;
+};
+
+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_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));
+	kfree(php_slot->name);
+	kfree(php_slot);
+}
+
+static inline void pnv_php_put_slot(struct pnv_php_slot *php_slot)
+{
+
+	if (WARN_ON(!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;
+}
+
+static 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;
+}
+
+/*
+ * 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;
+	int refcount;
+
+	for_each_child_of_node(parent, dn) {
+		pnv_php_detach_device_nodes(dn);
+
+		of_node_put(dn);
+		refcount = atomic_read(&dn->kobj.kref.refcount);
+		if (unlikely(refcount != 1))
+			pr_warn("Invalid refcount %d on <%s>\n",
+				refcount, of_node_full_name(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 (unlikely(ret))
+			break;
+
+		ret = pnv_php_populate_changeset(ocs, child);
+		if (unlikely(ret))
+			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 (unlikely(!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 (unlikely(!fdt1)) {
+		ret = -ENOMEM;
+		dev_warn(&php_slot->pdev->dev, "Cannot alloc FDT blob\n");
+		goto out;
+	}
+
+	ret = pnv_pci_get_device_tree(php_slot->dn->phandle, fdt1, 0x10000);
+	if (unlikely(ret)) {
+		dev_warn(&php_slot->pdev->dev, "Error %d getting FDT blob\n",
+			 ret);
+		goto free_fdt1;
+	}
+
+	fdt = kzalloc(fdt_totalsize(fdt1), GFP_KERNEL);
+	if (unlikely(!fdt)) {
+		ret = -ENOMEM;
+		dev_warn(&php_slot->pdev->dev, "Cannot %d bytes memory\n",
+			 fdt_totalsize(fdt1));
+		goto free_fdt1;
+	}
+
+	/* Unflatten device tree blob */
+	memcpy(fdt, fdt1, fdt_totalsize(fdt1));
+	dt = of_fdt_unflatten_tree(fdt, php_slot->dn, NULL);
+	if (unlikely(!dt)) {
+		ret = -EINVAL;
+		dev_warn(&php_slot->pdev->dev, "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 (unlikely(ret)) {
+		pnv_php_reverse_nodes(php_slot->dn);
+		dev_warn(&php_slot->pdev->dev, "Error %d populating changeset\n",
+			 ret);
+		goto free_dt;
+	}
+
+	php_slot->dn->child = NULL;
+	ret = of_changeset_apply(&php_slot->ocs);
+	if (unlikely(ret)) {
+		dev_warn(&php_slot->pdev->dev, "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 int pnv_php_set_slot_power_state(struct hotplug_slot *slot,
+					uint8_t state)
+{
+	struct pnv_php_slot *php_slot = slot->private;
+	struct opal_msg msg;
+	int ret;
+
+	ret = pnv_pci_set_power_state(php_slot->id, state, &msg);
+	if (likely(ret > 0)) {
+		if (be64_to_cpu(msg.params[1]) != php_slot->dn->phandle	||
+		    be64_to_cpu(msg.params[2]) != state			||
+		    be64_to_cpu(msg.params[3]) != OPAL_SUCCESS) {
+			dev_warn(&php_slot->pdev->dev, "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;
+		}
+	} else if (unlikely(ret < 0)) {
+		dev_warn(&php_slot->pdev->dev, "Error %d powering %s\n",
+			 ret, (state == OPAL_PCI_SLOT_POWER_ON) ? "on" : "off");
+		return ret;
+	}
+
+	if (state == OPAL_PCI_SLOT_POWER_OFF)
+		pnv_php_rmv_devtree(php_slot);
+	else
+		ret = pnv_php_add_devtree(php_slot);
+
+	return ret;
+}
+
+static int pnv_php_get_power_state(struct hotplug_slot *slot, u8 *state)
+{
+	struct pnv_php_slot *php_slot = slot->private;
+	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 (unlikely(ret)) {
+		dev_warn(&php_slot->pdev->dev, "Error %d getting power status\n",
+			 ret);
+	} else {
+		*state = power_state;
+		slot->info->power_status = power_state;
+	}
+
+	return 0;
+}
+
+static int pnv_php_get_adapter_state(struct hotplug_slot *slot, u8 *state)
+{
+	struct pnv_php_slot *php_slot = slot->private;
+	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 (likely(ret >= 0)) {
+		*state = presence;
+		slot->info->adapter_status = presence;
+		ret = 0;
+	} else {
+		dev_warn(&php_slot->pdev->dev, "Error %d getting presence\n",
+			 ret);
+	}
+
+	return ret;
+}
+
+static int pnv_php_set_attention_state(struct hotplug_slot *slot, u8 state)
+{
+	/* FIXME: Make it real once firmware supports it */
+	slot->info->attention_status = state;
+
+	return 0;
+}
+
+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 (unlikely(ret))
+		return ret;
+
+	/* Proceed if there have nothing behind the slot */
+	if (presence == OPAL_PCI_SLOT_EMPTY)
+		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 (unlikely(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 (unlikely(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_set_slot_power_state(slot, OPAL_PCI_SLOT_POWER_ON);
+	if (unlikely(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_enable_slot(struct hotplug_slot *slot)
+{
+	struct pnv_php_slot *php_slot = container_of(slot,
+						     struct pnv_php_slot, slot);
+
+	return pnv_php_enable(php_slot, true);
+}
+
+static int pnv_php_disable_slot(struct hotplug_slot *slot)
+{
+	struct pnv_php_slot *php_slot = slot->private;
+	int ret;
+
+	if (php_slot->state != PNV_PHP_STATE_POPULATED)
+		return 0;
+
+	/* 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 struct hotplug_slot_ops php_slot_ops = {
+	.get_power_status	= pnv_php_get_power_state,
+	.get_adapter_status	= pnv_php_get_adapter_state,
+	.set_attention_status	= pnv_php_set_attention_state,
+	.enable_slot		= pnv_php_enable_slot,
+	.disable_slot		= pnv_php_disable_slot,
+};
+
+static void pnv_php_release(struct hotplug_slot *slot)
+{
+	struct pnv_php_slot *php_slot = slot->private;
+	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;
+
+	label = of_get_property(dn, "ibm,slot-label", NULL);
+	if (unlikely(!label))
+		return NULL;
+
+	if (pnv_pci_get_slot_id(dn, &id))
+		return NULL;
+
+	bus = pci_find_bus_by_node(dn);
+	if (unlikely(!bus))
+		return NULL;
+
+	php_slot = kzalloc(sizeof(*php_slot), GFP_KERNEL);
+	if (unlikely(!php_slot))
+		return NULL;
+
+	php_slot->name = kstrdup(label, GFP_KERNEL);
+	if (unlikely(!php_slot->name)) {
+		kfree(php_slot);
+		return NULL;
+	}
+
+	if (likely(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;
+	php_slot->slot.info             = &php_slot->slot_info;
+	php_slot->slot.release          = pnv_php_release;
+	php_slot->slot.private          = php_slot;
+
+	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 (unlikely(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 (unlikely(ret)) {
+		dev_warn(&php_slot->pdev->dev, "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_register_one(struct device_node *dn)
+{
+	struct pnv_php_slot *php_slot;
+	const __be32 *prop32;
+	int ret;
+
+	/* Check if it's hotpluggable slot */
+	prop32 = of_get_property(dn, "ibm,slot-pluggable", NULL);
+	if (!prop32 || !of_read_number(prop32, 1))
+		return -ENXIO;
+
+	prop32 = of_get_property(dn, "ibm,reset-by-firmware", NULL);
+	if (!prop32 || !of_read_number(prop32, 1))
+		return -ENXIO;
+
+	php_slot = pnv_php_alloc_slot(dn);
+	if (unlikely(!php_slot))
+		return -ENODEV;
+
+	ret = pnv_php_register_slot(php_slot);
+	if (unlikely(ret))
+		goto free_slot;
+
+	ret = pnv_php_enable(php_slot, false);
+	if (unlikely(ret))
+		goto unregister_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;
+	pnv_php_put_slot(php_slot);
+	pci_hp_deregister(&php_slot->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);
+
+	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);
+}
+
+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);