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authorAlexander Gordeev <agordeev@redhat.com>2013-12-30 08:28:15 +0100
committerBjorn Helgaas <bhelgaas@google.com>2014-01-03 17:17:55 -0700
commitff1aa430a2fa43189e89c7ddd559f0bee2298288 (patch)
tree731237d3f796f92aa31b41a8fda7f0e38c707fbb
parent7b92b4f61ec49cb1a5813298f35258bd7ecd3667 (diff)
PCI/MSI: Add pci_msix_vec_count()
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>
-rw-r--r--Documentation/PCI/MSI-HOWTO.txt13
-rw-r--r--drivers/pci/msi.c18
-rw-r--r--drivers/pci/pcie/portdrv_core.c7
-rw-r--r--include/linux/pci.h6
4 files changed, 33 insertions, 11 deletions
diff --git a/Documentation/PCI/MSI-HOWTO.txt b/Documentation/PCI/MSI-HOWTO.txt
index aa4ad987510d..b58f4a4d14bb 100644
--- a/Documentation/PCI/MSI-HOWTO.txt
+++ b/Documentation/PCI/MSI-HOWTO.txt
@@ -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
diff --git a/drivers/pci/msi.c b/drivers/pci/msi.c
index 76507ab13beb..bd18ecf74c55 100644
--- a/drivers/pci/msi.c
+++ b/drivers/pci/msi.c
@@ -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;
diff --git a/drivers/pci/pcie/portdrv_core.c b/drivers/pci/pcie/portdrv_core.c
index 0b6e76604068..4ab719826dd7 100644
--- a/drivers/pci/pcie/portdrv_core.c
+++ b/drivers/pci/pcie/portdrv_core.c
@@ -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;
diff --git a/include/linux/pci.h b/include/linux/pci.h
index 86dcf006adcc..cf6125ba649d 100644
--- a/include/linux/pci.h
+++ b/include/linux/pci.h
@@ -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);