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 aa4ad987510d58fc58527320d239864df5c20d10..b58f4a4d14bb2c0560aee2b924c4789a26ded5f4 100644 (file)
--- 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 76507ab13bebafe2ab9138bde1df1ea069048fb4..bd18ecf74c55d07eceaf7a214511f72717df38e1 100644 (file)
--- 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 0b6e76604068043d9c261ddb9461757d4e64c279..4ab719826dd70e3d4f36550746252d48d99f5fde 100644 (file)
--- 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 86dcf006adccb8004f42fe36696e472ff9021525..cf6125ba649d440af7f24a4284b080d8aca4e810 100644 (file)
--- 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);