path: root/drivers/pci/hotplug/pnv_php.c

// SPDX-License-Identifier: GPL-2.0+
/*
 * PCI Hotplug Driver for PowerPC PowerNV platform.
 *
 * Copyright Gavin Shan, IBM Corporation 2016.
 */

#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"

#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_disable_irq(struct pnv_php_slot *php_slot,
				bool disable_device)
{
	struct pci_dev *pdev = php_slot->pdev;
	int irq = php_slot->irq;
	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 (php_slot->wq) {
		destroy_workqueue(php_slot->wq);
		php_slot->wq = NULL;
	}

	if (disable_device || irq > 0) {
		if (pdev->msix_enabled)
			pci_disable_msix(pdev);
		else if (pdev->msi_enabled)
			pci_disable_msi(pdev);

		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);
	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;