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PCI/MSI: Add pci_msix_vec_count()

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This creates an MSI-X counterpart for pci_msi_vec_count().  Device drivers
can use this function to obtain maximum number of MSI-X interrupts the
device supports and use that number in a subsequent call to
pci_enable_msix().

pci_msix_vec_count() supersedes pci_msix_table_size() and returns a
negative errno if device does not support MSI-X interrupts.  After this
update, callers must always check the returned value.

The only user of pci_msix_table_size() was the PCI-Express port driver,
which is also updated by this change.

Signed-off-by: Alexander Gordeev <agordeev@redhat.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Reviewed-by: Tejun Heo <tj@kernel.org>
This commit is contained in:
Alexander Gordeev 2013-12-30 08:28:15 +01:00 committed by Bjorn Helgaas
parent 7b92b4f61e
commit ff1aa430a2
4 changed files with 33 additions and 11 deletions
repo.diff.show_diff_stats Download patch file Download diff file Expand all files Collapse all files

13
Documentation/PCI/MSI-HOWTO.txt
View file

@ -243,6 +243,19 @@ MSI-X Table. This address is mapped by the PCI subsystem, and should not
be accessed directly by the device driver. If the driver wishes to
mask or unmask an interrupt, it should call disable_irq() / enable_irq().
4.3.4 pci_msix_vec_count
int pci_msix_vec_count(struct pci_dev *dev)
This function could be used to retrieve number of entries in the device
MSI-X table.
If this function returns a negative number, it indicates the device is
not capable of sending MSI-Xs.
If this function returns a positive number, it indicates the maximum
number of MSI-X interrupt vectors that could be allocated.
4.4 Handling devices implementing both MSI and MSI-X capabilities
If a device implements both MSI and MSI-X capabilities, it can

18
drivers/pci/msi.c
View file

@ -948,19 +948,25 @@ void pci_disable_msi(struct pci_dev *dev)
EXPORT_SYMBOL(pci_disable_msi);
/**
* pci_msix_table_size - return the number of device's MSI-X table entries
* pci_msix_vec_count - return the number of device's MSI-X table entries
* @dev: pointer to the pci_dev data structure of MSI-X device function
*/
int pci_msix_table_size(struct pci_dev *dev)
* This function returns the number of device's MSI-X table entries and
* therefore the number of MSI-X vectors device is capable of sending.
* It returns a negative errno if the device is not capable of sending MSI-X
* interrupts.
**/
int pci_msix_vec_count(struct pci_dev *dev)
{
u16 control;
if (!dev->msix_cap)
return 0;
return -EINVAL;
pci_read_config_word(dev, dev->msix_cap + PCI_MSIX_FLAGS, &control);
return msix_table_size(control);
}
EXPORT_SYMBOL(pci_msix_vec_count);
/**
* pci_enable_msix - configure device's MSI-X capability structure
@ -989,7 +995,9 @@ int pci_enable_msix(struct pci_dev *dev, struct msix_entry *entries, int nvec)
if (status)
return status;
nr_entries = pci_msix_table_size(dev);
nr_entries = pci_msix_vec_count(dev);
if (nr_entries < 0)
return nr_entries;
if (nvec > nr_entries)
return nr_entries;

7
drivers/pci/pcie/portdrv_core.c
View file

@ -79,9 +79,10 @@ static int pcie_port_enable_msix(struct pci_dev *dev, int *vectors, int mask)
u16 reg16;
u32 reg32;
nr_entries = pci_msix_table_size(dev);
if (!nr_entries)
return -EINVAL;
nr_entries = pci_msix_vec_count(dev);
if (nr_entries < 0)
return nr_entries;
BUG_ON(!nr_entries);
if (nr_entries > PCIE_PORT_MAX_MSIX_ENTRIES)
nr_entries = PCIE_PORT_MAX_MSIX_ENTRIES;

6
include/linux/pci.h
View file

@ -1169,9 +1169,9 @@ static inline void pci_msi_shutdown(struct pci_dev *dev)
static inline void pci_disable_msi(struct pci_dev *dev)
{ }
static inline int pci_msix_table_size(struct pci_dev *dev)
static inline int pci_msix_vec_count(struct pci_dev *dev)
{
return 0;
return -ENOSYS;
}
static inline int pci_enable_msix(struct pci_dev *dev,
struct msix_entry *entries, int nvec)
@ -1198,7 +1198,7 @@ int pci_msi_vec_count(struct pci_dev *dev);
int pci_enable_msi_block(struct pci_dev *dev, int nvec);
void pci_msi_shutdown(struct pci_dev *dev);
void pci_disable_msi(struct pci_dev *dev);
int pci_msix_table_size(struct pci_dev *dev);
int pci_msix_vec_count(struct pci_dev *dev);
int pci_enable_msix(struct pci_dev *dev, struct msix_entry *entries, int nvec);
void pci_msix_shutdown(struct pci_dev *dev);
void pci_disable_msix(struct pci_dev *dev);