[PATCH 1/9 v2] pci:msi: add weak function for returning msi region info

[Bharat Bhushan <r65777@freescale.com>]

In Aperture type of IOMMU (like FSL PAMU), VFIO-iommu system need to know
the MSI region to map its window in h/w. This patch just defines the
required weak functions only and will be used by followup patches.

Signed-off-by: Bharat Bhushan <bharat.bhushan@freescale.com>
---
v1->v2
 - Added description on "struct msi_region" 

 drivers/pci/msi.c   |   22 ++++++++++++++++++++++
 include/linux/msi.h |   14 ++++++++++++++
 2 files changed, 36 insertions(+), 0 deletions(-)

diff --git a/drivers/pci/msi.c b/drivers/pci/msi.c
index d5f90d6..2643a29 100644
--- a/drivers/pci/msi.c
+++ b/drivers/pci/msi.c
@@ -67,6 +67,28 @@ int __weak arch_msi_check_device(struct pci_dev *dev, int nvec, int type)
 	return chip->check_device(chip, dev, nvec, type);
 }
 
+int __weak arch_msi_get_region_count(void)
+{
+	return 0;
+}
+
+int __weak arch_msi_get_region(int region_num, struct msi_region *region)
+{
+	return 0;
+}
+
+int msi_get_region_count(void)
+{
+	return arch_msi_get_region_count();
+}
+EXPORT_SYMBOL(msi_get_region_count);
+
+int msi_get_region(int region_num, struct msi_region *region)
+{
+	return arch_msi_get_region(region_num, region);
+}
+EXPORT_SYMBOL(msi_get_region);
+
 int __weak arch_setup_msi_irqs(struct pci_dev *dev, int nvec, int type)
 {
 	struct msi_desc *entry;
diff --git a/include/linux/msi.h b/include/linux/msi.h
index b17ead8..ade1480 100644
--- a/include/linux/msi.h
+++ b/include/linux/msi.h
@@ -51,6 +51,18 @@ struct msi_desc {
 };
 
 /*
+ * This structure is used to get
+ * - physical address
+ * - size
+ * of a msi region
+ */
+struct msi_region {
+	int region_num; /* MSI region number */
+	dma_addr_t addr; /* Address of MSI region */
+	size_t size; /* Size of MSI region */
+};
+
+/*
  * The arch hooks to setup up msi irqs. Those functions are
  * implemented as weak symbols so that they /can/ be overriden by
  * architecture specific code if needed.
@@ -64,6 +76,8 @@ void arch_restore_msi_irqs(struct pci_dev *dev, int irq);
 
 void default_teardown_msi_irqs(struct pci_dev *dev);
 void default_restore_msi_irqs(struct pci_dev *dev, int irq);
+int arch_msi_get_region_count(void);
+int arch_msi_get_region(int region_num, struct msi_region *region);
 
 struct msi_chip {
 	struct module *owner;
-- 
1.7.0.4