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>
diff --git a/Documentation/PCI/MSI-HOWTO.txt b/Documentation/PCI/MSI-HOWTO.txt
index aa4ad98..b58f4a4 100644
--- a/Documentation/PCI/MSI-HOWTO.txt
+++ b/Documentation/PCI/MSI-HOWTO.txt
@@ -243,6 +243,19 @@
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 76507ab..bd18ecf 100644
--- a/drivers/pci/msi.c
+++ b/drivers/pci/msi.c
@@ -948,19 +948,25 @@
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 @@
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 0b6e766..4ab7198 100644
--- a/drivers/pci/pcie/portdrv_core.c
+++ b/drivers/pci/pcie/portdrv_core.c
@@ -79,9 +79,10 @@
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 86dcf00..cf6125b 100644
--- a/include/linux/pci.h
+++ b/include/linux/pci.h
@@ -1169,9 +1169,9 @@
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_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);
