/*
 * PCI Backend - Provides a Virtual PCI bus (with real devices)
 *               to the frontend
 *
 *   Author: Ryan Wilson <hap9@epoch.ncsc.mil> (vpci.c)
 *   Author: Tristan Gingold <tristan.gingold@bull.net>, from vpci.c
 */

#include <linux/list.h>
#include <linux/slab.h>
#include <linux/pci.h>
#include <linux/spinlock.h>
#include "pciback.h"

/* There are at most 32 slots in a pci bus.  */
#define PCI_SLOT_MAX 32

#define PCI_BUS_NBR 2

struct slot_dev_data {
	/* Access to dev_list must be protected by lock */
	struct pci_dev *slots[PCI_BUS_NBR][PCI_SLOT_MAX];
	spinlock_t lock;
};

struct pci_dev *pciback_get_pci_dev(struct pciback_device *pdev,
				    unsigned int domain, unsigned int bus,
				    unsigned int devfn)
{
	struct pci_dev *dev = NULL;
	struct slot_dev_data *slot_dev = pdev->pci_dev_data;
	unsigned long flags;

	if (domain != 0 || PCI_FUNC(devfn) != 0)
		return NULL;

	if (PCI_SLOT(devfn) >= PCI_SLOT_MAX || bus >= PCI_BUS_NBR)
		return NULL;

	spin_lock_irqsave(&slot_dev->lock, flags);
	dev = slot_dev->slots[bus][PCI_SLOT(devfn)];
	spin_unlock_irqrestore(&slot_dev->lock, flags);

	return dev;
}

int pciback_add_pci_dev(struct pciback_device *pdev, struct pci_dev *dev)
{
	int err = 0, slot, bus;
	struct slot_dev_data *slot_dev = pdev->pci_dev_data;
	unsigned long flags;

	if ((dev->class >> 24) == PCI_BASE_CLASS_BRIDGE) {
		err = -EFAULT;
		xenbus_dev_fatal(pdev->xdev, err,
				 "Can't export bridges on the virtual PCI bus");
		goto out;
	}

	spin_lock_irqsave(&slot_dev->lock, flags);

	/* Assign to a new slot on the virtual PCI bus */
	for (bus = 0; bus < PCI_BUS_NBR; bus++)
		for (slot = 0; slot < PCI_SLOT_MAX; slot++) {
			if (slot_dev->slots[bus][slot] == NULL) {
				printk(KERN_INFO
				       "pciback: slot: %s: assign to virtual slot %d, bus %d\n",
				       pci_name(dev), slot, bus);
				slot_dev->slots[bus][slot] = dev;
				goto unlock;
			}
		}

	err = -ENOMEM;
	xenbus_dev_fatal(pdev->xdev, err,
			 "No more space on root virtual PCI bus");

      unlock:
	spin_unlock_irqrestore(&slot_dev->lock, flags);
      out:
	return err;
}

void pciback_release_pci_dev(struct pciback_device *pdev, struct pci_dev *dev)
{
	int slot, bus;
	struct slot_dev_data *slot_dev = pdev->pci_dev_data;
	struct pci_dev *found_dev = NULL;
	unsigned long flags;

	spin_lock_irqsave(&slot_dev->lock, flags);

	for (bus = 0; bus < PCI_BUS_NBR; bus++)
		for (slot = 0; slot < PCI_SLOT_MAX; slot++) {
			if (slot_dev->slots[bus][slot] == dev) {
				slot_dev->slots[bus][slot] = NULL;
				found_dev = dev;
				goto out;
			}
		}

      out:
	spin_unlock_irqrestore(&slot_dev->lock, flags);

	if (found_dev)
		pcistub_put_pci_dev(found_dev);
}

int pciback_init_devices(struct pciback_device *pdev)
{
	int slot, bus;
	struct slot_dev_data *slot_dev;

	slot_dev = kmalloc(sizeof(*slot_dev), GFP_KERNEL);
	if (!slot_dev)
		return -ENOMEM;

	spin_lock_init(&slot_dev->lock);

	for (bus = 0; bus < PCI_BUS_NBR; bus++)
		for (slot = 0; slot < PCI_SLOT_MAX; slot++)
			slot_dev->slots[bus][slot] = NULL;

	pdev->pci_dev_data = slot_dev;

	return 0;
}

int pciback_publish_pci_roots(struct pciback_device *pdev,
			      publish_pci_root_cb publish_cb)
{
	/* The Virtual PCI bus has only one root */
	return publish_cb(pdev, 0, 0);
}

void pciback_release_devices(struct pciback_device *pdev)
{
	int slot, bus;
	struct slot_dev_data *slot_dev = pdev->pci_dev_data;
	struct pci_dev *dev;

	for (bus = 0; bus < PCI_BUS_NBR; bus++)
		for (slot = 0; slot < PCI_SLOT_MAX; slot++) {
			dev = slot_dev->slots[bus][slot];
			if (dev != NULL)
				pcistub_put_pci_dev(dev);
		}

	kfree(slot_dev);
	pdev->pci_dev_data = NULL;
}