Commit 4fe0d154 authored by Christoph Hellwig's avatar Christoph Hellwig Committed by Bjorn Helgaas
Browse files

PCI: Use positive flags in pci_alloc_irq_vectors() 



Instead of passing negative flags like PCI_IRQ_NOMSI to prevent use of
certain interrupt types, pass positive flags like PCI_IRQ_LEGACY,
PCI_IRQ_MSI, etc., to specify the acceptable interrupt types.

This is based on a number of pending driver conversions that just happend
to be a whole more obvious to read this way, and given that we have no
users in the tree yet it can still easily be done.

I've also added a PCI_IRQ_ALL_TYPES catchall to keep the case of accepting
all interrupt types very simple.

[bhelgaas: changelog, fix PCI_IRQ_AFFINITY doc typo, remove mention of
PCI_IRQ_NOLEGACY]
Signed-off-by: default avatarChristoph Hellwig <hch@lst.de>
Signed-off-by: default avatarBjorn Helgaas <bhelgaas@google.com>
Reviewed-by: default avatarAlexander Gordeev <agordeev@redhat.com>
parent 8b078c60

Documentation/PCI/MSI-HOWTO.txt

+10 −14
Original line number Diff line number Diff line
@@ -94,14 +94,11 @@ has a requirements for a minimum number of vectors the driver can pass a 
min_vecs argument set to this limit, and the PCI core will return -ENOSPC

if it can't meet the minimum number of vectors.



The flags argument should normally be set to 0, but can be used to pass the

PCI_IRQ_NOMSI and PCI_IRQ_NOMSIX flag in case a device claims to support

MSI or MSI-X, but the support is broken, or to pass PCI_IRQ_NOLEGACY in

case the device does not support legacy interrupt lines.



By default this function will spread the interrupts around the available

CPUs, but this feature can be disabled by passing the PCI_IRQ_NOAFFINITY

flag.

The flags argument is used to specify which type of interrupt can be used

by the device and the driver (PCI_IRQ_LEGACY, PCI_IRQ_MSI, PCI_IRQ_MSIX).

A convenient short-hand (PCI_IRQ_ALL_TYPES) is also available to ask for

any possible kind of interrupt.  If the PCI_IRQ_AFFINITY flag is set,

pci_alloc_irq_vectors() will spread the interrupts around the available CPUs.



To get the Linux IRQ numbers passed to request_irq() and free_irq() and the

vectors, use the following function:
@@ -131,7 +128,7 @@ larger than the number supported by the device it will automatically be 
capped to the supported limit, so there is no need to query the number of

vectors supported beforehand:



	nvec = pci_alloc_irq_vectors(pdev, 1, nvec, 0);

	nvec = pci_alloc_irq_vectors(pdev, 1, nvec, PCI_IRQ_ALL_TYPES)

	if (nvec < 0)

		goto out_err;
@@ -140,7 +137,7 @@ interrupts it can request a particular number of interrupts by passing that 
number to pci_alloc_irq_vectors() function as both 'min_vecs' and

'max_vecs' parameters:



	ret = pci_alloc_irq_vectors(pdev, nvec, nvec, 0);

	ret = pci_alloc_irq_vectors(pdev, nvec, nvec, PCI_IRQ_ALL_TYPES);

	if (ret < 0)

		goto out_err;
@@ -148,15 +145,14 @@ The most notorious example of the request type described above is enabling 
the single MSI mode for a device.  It could be done by passing two 1s as

'min_vecs' and 'max_vecs':



	ret = pci_alloc_irq_vectors(pdev, 1, 1, 0);

	ret = pci_alloc_irq_vectors(pdev, 1, 1, PCI_IRQ_ALL_TYPES);

	if (ret < 0)

		goto out_err;



Some devices might not support using legacy line interrupts, in which case

the PCI_IRQ_NOLEGACY flag can be used to fail the request if the platform

can't provide MSI or MSI-X interrupts:

the driver can specify that only MSI or MSI-X is acceptable:



	nvec = pci_alloc_irq_vectors(pdev, 1, nvec, PCI_IRQ_NOLEGACY);

	nvec = pci_alloc_irq_vectors(pdev, 1, nvec, PCI_IRQ_MSI | PCI_IRQ_MSIX);

	if (nvec < 0)

		goto out_err;

drivers/pci/msi.c

+7 −8
Original line number Diff line number Diff line
@@ -1069,7 +1069,7 @@ static int __pci_enable_msi_range(struct pci_dev *dev, int minvec, int maxvec, 
		nvec = maxvec;



	for (;;) {

		if (!(flags & PCI_IRQ_NOAFFINITY)) {

		if (flags & PCI_IRQ_AFFINITY) {

			dev->irq_affinity = irq_create_affinity_mask(&nvec);

			if (nvec < minvec)

				return -ENOSPC;
@@ -1105,7 +1105,7 @@ static int __pci_enable_msi_range(struct pci_dev *dev, int minvec, int maxvec, 
 **/

int pci_enable_msi_range(struct pci_dev *dev, int minvec, int maxvec)

{

	return __pci_enable_msi_range(dev, minvec, maxvec, PCI_IRQ_NOAFFINITY);

	return __pci_enable_msi_range(dev, minvec, maxvec, 0);

}

EXPORT_SYMBOL(pci_enable_msi_range);
@@ -1120,7 +1120,7 @@ static int __pci_enable_msix_range(struct pci_dev *dev, 
		return -ERANGE;



	for (;;) {

		if (!(flags & PCI_IRQ_NOAFFINITY)) {

		if (flags & PCI_IRQ_AFFINITY) {

			dev->irq_affinity = irq_create_affinity_mask(&nvec);

			if (nvec < minvec)

				return -ENOSPC;
@@ -1160,8 +1160,7 @@ static int __pci_enable_msix_range(struct pci_dev *dev, 
int pci_enable_msix_range(struct pci_dev *dev, struct msix_entry *entries,

		int minvec, int maxvec)

{

	return __pci_enable_msix_range(dev, entries, minvec, maxvec,

			PCI_IRQ_NOAFFINITY);

	return __pci_enable_msix_range(dev, entries, minvec, maxvec, 0);

}

EXPORT_SYMBOL(pci_enable_msix_range);
@@ -1187,21 +1186,21 @@ int pci_alloc_irq_vectors(struct pci_dev *dev, unsigned int min_vecs, 
{

	int vecs = -ENOSPC;



	if (!(flags & PCI_IRQ_NOMSIX)) {

	if (flags & PCI_IRQ_MSIX) {

		vecs = __pci_enable_msix_range(dev, NULL, min_vecs, max_vecs,

				flags);

		if (vecs > 0)

			return vecs;

	}



	if (!(flags & PCI_IRQ_NOMSI)) {

	if (flags & PCI_IRQ_MSI) {

		vecs = __pci_enable_msi_range(dev, min_vecs, max_vecs, flags);

		if (vecs > 0)

			return vecs;

	}



	/* use legacy irq if allowed */

	if (!(flags & PCI_IRQ_NOLEGACY) && min_vecs == 1)

	if ((flags & PCI_IRQ_LEGACY) && min_vecs == 1)

		return 1;

	return vecs;

}

include/linux/pci.h

+6 −4
Original line number Diff line number Diff line
@@ -1251,10 +1251,12 @@ resource_size_t pcibios_iov_resource_alignment(struct pci_dev *dev, int resno); 
int pci_set_vga_state(struct pci_dev *pdev, bool decode,

		      unsigned int command_bits, u32 flags);



#define PCI_IRQ_NOLEGACY	(1 << 0) /* don't use legacy interrupts */

#define PCI_IRQ_NOMSI		(1 << 1) /* don't use MSI interrupts */

#define PCI_IRQ_NOMSIX		(1 << 2) /* don't use MSI-X interrupts */

#define PCI_IRQ_NOAFFINITY	(1 << 3) /* don't auto-assign affinity */

#define PCI_IRQ_LEGACY		(1 << 0) /* allow legacy interrupts */

#define PCI_IRQ_MSI		(1 << 1) /* allow MSI interrupts */

#define PCI_IRQ_MSIX		(1 << 2) /* allow MSI-X interrupts */

#define PCI_IRQ_AFFINITY	(1 << 3) /* auto-assign affinity */

#define PCI_IRQ_ALL_TYPES \

	(PCI_IRQ_LEGACY | PCI_IRQ_MSI | PCI_IRQ_MSIX)



/* kmem_cache style wrapper around pci_alloc_consistent() */

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