[Xen-devel] [PATCH 4/8] [xen/pci] Provide a registration mechanism for the PCI frontend module functions.

[Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>]

This registration mechanism allows us to "hook-up" the PCI frontend
enable/disable MSI/MSI-X calls when the module (or if it is compiled in)
is loaded. If it is not loaded, the caller (next patch) will just
call an empty stub.

Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>
---
 arch/x86/include/asm/xen/pci.h |   45 ++++++++++++++++++++++++++++-----------
 1 files changed, 32 insertions(+), 13 deletions(-)

diff --git a/arch/x86/include/asm/xen/pci.h b/arch/x86/include/asm/xen/pci.h
index 6c022c8..9f0a14b 100644
--- a/arch/x86/include/asm/xen/pci.h
+++ b/arch/x86/include/asm/xen/pci.h
@@ -35,24 +35,43 @@ static inline int xen_setup_msi_irqs(struct pci_dev *dev, 
int nvec, int type)
        return -1;
 }
 #endif
-#if defined(CONFIG_PCI_MSI) && defined(CONFIG_XEN_PCIDEV_FRONTEND)
-/* Defined in drivers/pci/xen-pcifront.c */
-int pci_frontend_enable_msi(struct pci_dev *dev, int **vectors);
-void pci_frontend_disable_msi(struct pci_dev *dev);
-int pci_frontend_enable_msix(struct pci_dev *dev,
-                            int **vectors, int nvec);
-void pci_frontend_disable_msix(struct pci_dev *dev);
-#else
-static inline int pci_frontend_enable_msi(struct pci_dev *dev, int **vectors)
+#if defined(CONFIG_PCI_MSI)
+
+/* The drivers/pci/xen-pcifront.c sets this structure to
+ * its own functions.
+ */
+struct xen_pci_frontend_ops {
+       int (*enable_msi)(struct pci_dev *dev, int **vectors);
+       void (*disable_msi)(struct pci_dev *dev);
+       int (*enable_msix)(struct pci_dev *dev, int **vectors, int nvec);
+       void (*disable_msix)(struct pci_dev *dev);
+};
+
+extern struct xen_pci_frontend_ops *xen_pci_frontend;
+       
+static inline int xen_pci_frontend_enable_msi(struct pci_dev *dev,
+                                             int **vectors)
 {
+       if (xen_pci_frontend && xen_pci_frontend->enable_msi)
+               return xen_pci_frontend->enable_msi(dev, vectors);
        return -1;
 }
-static inline void pci_frontend_disable_msi(struct pci_dev *dev) { }
-static inline int pci_frontend_enable_msix(struct pci_dev *dev,
-                                          int **vectors, int nvec)
+static inline void xen_pci_frontend_disable_msi(struct pci_dev *dev)
 {
+       if (xen_pci_frontend && xen_pci_frontend->disable_msi)
+                       xen_pci_frontend->disable_msi(dev);
+}
+static inline int xen_pci_frontend_enable_msix(struct pci_dev *dev,
+                                              int **vectors, int nvec)
+{
+       if (xen_pci_frontend && xen_pci_frontend->enable_msix)
+               return xen_pci_frontend->enable_msix(dev, vectors, nvec);
        return -1;
 }
-static inline void pci_frontend_disable_msix(struct pci_dev *dev) { }
+static inline void xen_pci_frontend_disable_msix(struct pci_dev *dev)
+{
+       if (xen_pci_frontend && xen_pci_frontend->disable_msix)
+                       xen_pci_frontend->disable_msix(dev);
+}
 #endif
 #endif /* _ASM_X86_XEN_PCI_H */
-- 
1.6.2.5


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