--- /dev/null
+From 45ab9702fb47d18dca116b3a0509efa19fbcb27a Mon Sep 17 00:00:00 2001
+From: Thierry Reding <thierry.reding@avionic-design.de>
+Date: Thu, 16 May 2013 17:55:18 +0200
+Subject: [PATCH] of/pci: Add of_pci_get_devfn() function
+
+commit 45ab9702fb47d18dca116b3a0509efa19fbcb27a upstream.
+
+This function can be used to parse the device and function number from a
+standard 5-cell PCI resource. PCI_SLOT() and PCI_FUNC() can be used on
+the returned value obtain the device and function numbers respectively.
+
+Signed-off-by: Thierry Reding <thierry.reding@avionic-design.de>
+Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
+Signed-off-by: Jason Cooper <jason@lakedaemon.net>
+---
+ drivers/of/of_pci.c | 34 +++++++++++++++++++++++++++++-----
+ include/linux/of_pci.h | 1 +
+ 2 files changed, 30 insertions(+), 5 deletions(-)
+
+--- a/drivers/of/of_pci.c
++++ b/drivers/of/of_pci.c
+@@ -5,14 +5,15 @@
+ #include <asm/prom.h>
+
+ static inline int __of_pci_pci_compare(struct device_node *node,
+- unsigned int devfn)
++ unsigned int data)
+ {
+- unsigned int size;
+- const __be32 *reg = of_get_property(node, "reg", &size);
++ int devfn;
+
+- if (!reg || size < 5 * sizeof(__be32))
++ devfn = of_pci_get_devfn(node);
++ if (devfn < 0)
+ return 0;
+- return ((be32_to_cpup(®[0]) >> 8) & 0xff) == devfn;
++
++ return devfn == data;
+ }
+
+ struct device_node *of_pci_find_child_device(struct device_node *parent,
+@@ -40,3 +41,26 @@ struct device_node *of_pci_find_child_de
+ return NULL;
+ }
+ EXPORT_SYMBOL_GPL(of_pci_find_child_device);
++
++/**
++ * of_pci_get_devfn() - Get device and function numbers for a device node
++ * @np: device node
++ *
++ * Parses a standard 5-cell PCI resource and returns an 8-bit value that can
++ * be passed to the PCI_SLOT() and PCI_FUNC() macros to extract the device
++ * and function numbers respectively. On error a negative error code is
++ * returned.
++ */
++int of_pci_get_devfn(struct device_node *np)
++{
++ unsigned int size;
++ const __be32 *reg;
++
++ reg = of_get_property(np, "reg", &size);
++
++ if (!reg || size < 5 * sizeof(__be32))
++ return -EINVAL;
++
++ return (be32_to_cpup(reg) >> 8) & 0xff;
++}
++EXPORT_SYMBOL_GPL(of_pci_get_devfn);
+--- a/include/linux/of_pci.h
++++ b/include/linux/of_pci.h
+@@ -10,5 +10,6 @@ int of_irq_map_pci(const struct pci_dev
+ struct device_node;
+ struct device_node *of_pci_find_child_device(struct device_node *parent,
+ unsigned int devfn);
++int of_pci_get_devfn(struct device_node *np);
+
+ #endif