[PATCH 1/2] PCI/MSI: Introduce pci_msix_table_size()

["Rafael J. Wysocki" <rjw@xxxxxxx>]

From: Rafael J. Wysocki <rjw@xxxxxxx>

Introduce new function pci_msix_table_size() returning the size of
the MSI-X table of given PCI device or 0 if the device doesn't
support MSI-X.

Signed-off-by: Rafael J. Wysocki <rjw@xxxxxxx>
Reviewed-by: Hidetoshi Seto <seto.hidetoshi@xxxxxxxxxxxxxx>
---
 drivers/pci/msi.c   |   24 +++++++++++++++++++-----
 include/linux/pci.h |    5 +++++
 2 files changed, 24 insertions(+), 5 deletions(-)

Index: linux-2.6/drivers/pci/msi.c
===================================================================
--- linux-2.6.orig/drivers/pci/msi.c
+++ linux-2.6/drivers/pci/msi.c
@@ -670,6 +670,23 @@ static int msi_free_irqs(struct pci_dev*
 }
 
 /**
+ * pci_msix_table_size - 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)
+{
+	int pos;
+	u16 control;
+
+	pos = pci_find_capability(dev, PCI_CAP_ID_MSIX);
+	if (!pos)
+		return 0;
+
+	pci_read_config_word(dev, msi_control_reg(pos), &control);
+	return multi_msix_capable(control);
+}
+
+/**
  * pci_enable_msix - configure device's MSI-X capability structure
  * @dev: pointer to the pci_dev data structure of MSI-X device function
  * @entries: pointer to an array of MSI-X entries
@@ -686,9 +703,8 @@ static int msi_free_irqs(struct pci_dev*
  **/
 int pci_enable_msix(struct pci_dev* dev, struct msix_entry *entries, int nvec)
 {
-	int status, pos, nr_entries;
+	int status, nr_entries;
 	int i, j;
-	u16 control;
 
 	if (!entries)
  		return -EINVAL;
@@ -697,9 +713,7 @@ int pci_enable_msix(struct pci_dev* dev,
 	if (status)
 		return status;
 
-	pos = pci_find_capability(dev, PCI_CAP_ID_MSIX);
-	pci_read_config_word(dev, msi_control_reg(pos), &control);
-	nr_entries = multi_msix_capable(control);
+	nr_entries = pci_msix_table_size(dev);
 	if (nvec > nr_entries)
 		return -EINVAL;
 
Index: linux-2.6/include/linux/pci.h
===================================================================
--- linux-2.6.orig/include/linux/pci.h
+++ linux-2.6/include/linux/pci.h
@@ -799,6 +799,10 @@ static inline void pci_msi_shutdown(stru
 static inline void pci_disable_msi(struct pci_dev *dev)
 { }
 
+static inline int pci_msix_table_size(struct pci_dev *dev)
+{
+	return 0;
+}
 static inline int pci_enable_msix(struct pci_dev *dev,
 				  struct msix_entry *entries, int nvec)
 {
@@ -823,6 +827,7 @@ static inline int pci_msi_enabled(void)
 extern int pci_enable_msi(struct pci_dev *dev);
 extern void pci_msi_shutdown(struct pci_dev *dev);
 extern void pci_disable_msi(struct pci_dev *dev);
+extern int pci_msix_table_size(struct pci_dev *dev);
 extern int pci_enable_msix(struct pci_dev *dev,
 	struct msix_entry *entries, int nvec);
 extern void pci_msix_shutdown(struct pci_dev *dev);

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