msi.c

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 * single MSI-X irq. A return of zero indicates the successful setup of
 * requested MSI-X entries with allocated irqs or non-zero for otherwise.
 **/
static int msix_capability_init(struct pci_dev *dev,
				struct msix_entry *entries, int nvec)
{
	struct msi_desc *entry;
	int pos, i, j, nr_entries, ret;
	unsigned long phys_addr;
	u32 table_offset;
 	u16 control;
	u8 bir;
	void __iomem *base;

	msix_set_enable(dev, 0);/* Ensure msix is disabled as I set it up */

   	pos = pci_find_capability(dev, PCI_CAP_ID_MSIX);
	/* Request & Map MSI-X table region */
 	pci_read_config_word(dev, msi_control_reg(pos), &control);
	nr_entries = multi_msix_capable(control);

 	pci_read_config_dword(dev, msix_table_offset_reg(pos), &table_offset);
	bir = (u8)(table_offset & PCI_MSIX_FLAGS_BIRMASK);
	table_offset &= ~PCI_MSIX_FLAGS_BIRMASK;
	phys_addr = pci_resource_start (dev, bir) + table_offset;
	base = ioremap_nocache(phys_addr, nr_entries * PCI_MSIX_ENTRY_SIZE);
	if (base == NULL)
		return -ENOMEM;

	/* MSI-X Table Initialization */
	for (i = 0; i < nvec; i++) {
		entry = alloc_msi_entry();
		if (!entry)
			break;

 		j = entries[i].entry;
		entry->msi_attrib.type = PCI_CAP_ID_MSIX;
		entry->msi_attrib.is_64 = 1;
		entry->msi_attrib.entry_nr = j;
		entry->msi_attrib.maskbit = 1;
		entry->msi_attrib.masked = 1;
		entry->msi_attrib.default_irq = dev->irq;
		entry->msi_attrib.pos = pos;
		entry->dev = dev;
		entry->mask_base = base;

		list_add_tail(&entry->list, &dev->msi_list);
	}

	ret = arch_setup_msi_irqs(dev, nvec, PCI_CAP_ID_MSIX);
	if (ret) {
		int avail = 0;
		list_for_each_entry(entry, &dev->msi_list, list) {
			if (entry->irq != 0) {
				avail++;
			}
		}

		msi_free_irqs(dev);

		/* If we had some success report the number of irqs
		 * we succeeded in setting up.
		 */
		if (avail == 0)
			avail = ret;
		return avail;
	}

	i = 0;
	list_for_each_entry(entry, &dev->msi_list, list) {
		entries[i].vector = entry->irq;
		set_irq_msi(entry->irq, entry);
		i++;
	}
	/* Set MSI-X enabled bits */
	pci_intx_for_msi(dev, 0);
	msix_set_enable(dev, 1);
	dev->msix_enabled = 1;

	return 0;
}

/**
 * pci_msi_check_device - check whether MSI may be enabled on a device
 * @dev: pointer to the pci_dev data structure of MSI device function
 * @nvec: how many MSIs have been requested ?
 * @type: are we checking for MSI or MSI-X ?
 *
 * Look at global flags, the device itself, and its parent busses
 * to determine if MSI/-X are supported for the device. If MSI/-X is
 * supported return 0, else return an error code.
 **/
static int pci_msi_check_device(struct pci_dev* dev, int nvec, int type)
{
	struct pci_bus *bus;
	int ret;

	/* MSI must be globally enabled and supported by the device */
	if (!pci_msi_enable || !dev || dev->no_msi)
		return -EINVAL;

	/*
	 * You can't ask to have 0 or less MSIs configured.
	 *  a) it's stupid ..
	 *  b) the list manipulation code assumes nvec >= 1.
	 */
	if (nvec < 1)
		return -ERANGE;

	/* Any bridge which does NOT route MSI transactions from it's
	 * secondary bus to it's primary bus must set NO_MSI flag on
	 * the secondary pci_bus.
	 * We expect only arch-specific PCI host bus controller driver
	 * or quirks for specific PCI bridges to be setting NO_MSI.
	 */
	for (bus = dev->bus; bus; bus = bus->parent)
		if (bus->bus_flags & PCI_BUS_FLAGS_NO_MSI)
			return -EINVAL;

	ret = arch_msi_check_device(dev, nvec, type);
	if (ret)
		return ret;

	if (!pci_find_capability(dev, type))
		return -EINVAL;

	return 0;
}

/**
 * pci_enable_msi - configure device's MSI capability structure
 * @dev: pointer to the pci_dev data structure of MSI device function
 *
 * Setup the MSI capability structure of device function with
 * a single MSI irq upon its software driver call to request for
 * MSI mode enabled on its hardware device function. A return of zero
 * indicates the successful setup of an entry zero with the new MSI
 * irq or non-zero for otherwise.
 **/
int pci_enable_msi(struct pci_dev* dev)
{
	int status;

	status = pci_msi_check_device(dev, 1, PCI_CAP_ID_MSI);
	if (status)
		return status;

	WARN_ON(!!dev->msi_enabled);

	/* Check whether driver already requested for MSI-X irqs */
	if (dev->msix_enabled) {
		printk(KERN_INFO "PCI: %s: Can't enable MSI.  "
			"Device already has MSI-X enabled\n",
			pci_name(dev));
		return -EINVAL;
	}
	status = msi_capability_init(dev);
	return status;
}
EXPORT_SYMBOL(pci_enable_msi);

void pci_disable_msi(struct pci_dev* dev)
{
	struct msi_desc *entry;
	int default_irq;

	if (!pci_msi_enable || !dev || !dev->msi_enabled)
		return;

	msi_set_enable(dev, 0);
	pci_intx_for_msi(dev, 1);
	dev->msi_enabled = 0;

	BUG_ON(list_empty(&dev->msi_list));
	entry = list_entry(dev->msi_list.next, struct msi_desc, list);
	if (!entry->dev || entry->msi_attrib.type != PCI_CAP_ID_MSI) {
		return;
	}

	default_irq = entry->msi_attrib.default_irq;
	msi_free_irqs(dev);

	/* Restore dev->irq to its default pin-assertion irq */
	dev->irq = default_irq;
}
EXPORT_SYMBOL(pci_disable_msi);

static int msi_free_irqs(struct pci_dev* dev)
{
	struct msi_desc *entry, *tmp;

	list_for_each_entry(entry, &dev->msi_list, list) {
		if (entry->irq)
			BUG_ON(irq_has_action(entry->irq));
	}

	arch_teardown_msi_irqs(dev);

	list_for_each_entry_safe(entry, tmp, &dev->msi_list, list) {
		if (entry->msi_attrib.type == PCI_CAP_ID_MSIX) {
			writel(1, entry->mask_base + entry->msi_attrib.entry_nr
				  * PCI_MSIX_ENTRY_SIZE
				  + PCI_MSIX_ENTRY_VECTOR_CTRL_OFFSET);

			if (list_is_last(&entry->list, &dev->msi_list))
				iounmap(entry->mask_base);
		}
		list_del(&entry->list);
		kfree(entry);
	}

	return 0;
}

/**
 * pci_enable_msix - configure device's MSI-X capability structure
 * @dev: pointer to the pci_dev data structure of MSI-X device function
 * @entries: pointer to an array of MSI-X entries
 * @nvec: number of MSI-X irqs requested for allocation by device driver
 *
 * Setup the MSI-X capability structure of device function with the number
 * of requested irqs upon its software driver call to request for
 * MSI-X mode enabled on its hardware device function. A return of zero
 * indicates the successful configuration of MSI-X capability structure
 * with new allocated MSI-X irqs. A return of < 0 indicates a failure.
 * Or a return of > 0 indicates that driver request is exceeding the number
 * of irqs available. Driver should use the returned value to re-send
 * its request.
 **/
int pci_enable_msix(struct pci_dev* dev, struct msix_entry *entries, int nvec)
{
	int status, pos, nr_entries;
	int i, j;
	u16 control;

	if (!entries)
 		return -EINVAL;

	status = pci_msi_check_device(dev, nvec, PCI_CAP_ID_MSIX);
	if (status)
		return status;

	pos = pci_find_capability(dev, PCI_CAP_ID_MSIX);
	pci_read_config_word(dev, msi_control_reg(pos), &control);
	nr_entries = multi_msix_capable(control);
	if (nvec > nr_entries)
		return -EINVAL;

	/* Check for any invalid entries */
	for (i = 0; i < nvec; i++) {
		if (entries[i].entry >= nr_entries)
			return -EINVAL;		/* invalid entry */
		for (j = i + 1; j < nvec; j++) {
			if (entries[i].entry == entries[j].entry)
				return -EINVAL;	/* duplicate entry */
		}
	}
	WARN_ON(!!dev->msix_enabled);

	/* Check whether driver already requested for MSI irq */
   	if (dev->msi_enabled) {
		printk(KERN_INFO "PCI: %s: Can't enable MSI-X.  "
		       "Device already has an MSI irq assigned\n",
		       pci_name(dev));
		return -EINVAL;
	}
	status = msix_capability_init(dev, entries, nvec);
	return status;
}
EXPORT_SYMBOL(pci_enable_msix);

static void msix_free_all_irqs(struct pci_dev *dev)
{
	msi_free_irqs(dev);
}

void pci_disable_msix(struct pci_dev* dev)
{
	if (!pci_msi_enable || !dev || !dev->msix_enabled)
		return;

	msix_set_enable(dev, 0);
	pci_intx_for_msi(dev, 1);
	dev->msix_enabled = 0;

	msix_free_all_irqs(dev);
}
EXPORT_SYMBOL(pci_disable_msix);

/**
 * msi_remove_pci_irq_vectors - reclaim MSI(X) irqs to unused state
 * @dev: pointer to the pci_dev data structure of MSI(X) device function
 *
 * Being called during hotplug remove, from which the device function
 * is hot-removed. All previous assigned MSI/MSI-X irqs, if
 * allocated for this device function, are reclaimed to unused state,
 * which may be used later on.
 **/
void msi_remove_pci_irq_vectors(struct pci_dev* dev)
{
	if (!pci_msi_enable || !dev)
 		return;

	if (dev->msi_enabled)
		msi_free_irqs(dev);

	if (dev->msix_enabled)
		msix_free_all_irqs(dev);
}

void pci_no_msi(void)
{
	pci_msi_enable = 0;
}

void pci_msi_init_pci_dev(struct pci_dev *dev)
{
	INIT_LIST_HEAD(&dev->msi_list);
}


/* Arch hooks */

int __attribute__ ((weak))
arch_msi_check_device(struct pci_dev* dev, int nvec, int type)
{
	return 0;
}

int __attribute__ ((weak))
arch_setup_msi_irq(struct pci_dev *dev, struct msi_desc *entry)
{
	return 0;
}

int __attribute__ ((weak))
arch_setup_msi_irqs(struct pci_dev *dev, int nvec, int type)
{
	struct msi_desc *entry;
	int ret;

	list_for_each_entry(entry, &dev->msi_list, list) {
		ret = arch_setup_msi_irq(dev, entry);
		if (ret)
			return ret;
	}

	return 0;
}

void __attribute__ ((weak)) arch_teardown_msi_irq(unsigned int irq)
{
	return;
}

void __attribute__ ((weak))
arch_teardown_msi_irqs(struct pci_dev *dev)
{
	struct msi_desc *entry;

	list_for_each_entry(entry, &dev->msi_list, list) {
		if (entry->irq != 0)
			arch_teardown_msi_irq(entry->irq);
	}
}