of: pci: import of_pci_get_devfn()

Marvell MVEBU PCIe driver requires of_pcie_get_devfn(), import it from
Linux.

Signed-off-by: Sebastian Hesselbarth <sebastian.hesselbarth@gmail.com>
Acked-by: Lucas Stach <l.stach@pengutronix.de>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

drivers/of/Kconfig

@@ -27,6 +27,12 @@ config OF_GPIO
 	depends on OFDEVICE
 	def_bool y
 
+config OF_PCI
+	bool
+	depends on PCI
+	help
+	  OpenFirmware PCI bus accessors
+
 config OF_BAREBOX_DRIVERS
 	depends on OFDEVICE
 	depends on ENV_HANDLING

drivers/of/Makefile

@@ -1,6 +1,7 @@
 obj-y += address.o base.o fdt.o platform.o
 obj-$(CONFIG_OFTREE_MEM_GENERIC) += mem_generic.o
 obj-$(CONFIG_OF_GPIO) += of_gpio.o
+obj-$(CONFIG_OF_PCI) += of_pci.o
 obj-y += partition.o
 obj-y += of_net.o
 obj-$(CONFIG_MTD) += of_mtd.o

drivers/of/of_pci.c

@@ -0,0 +1,27 @@
+#include <common.h>
+#include <errno.h>
+#include <of.h>
+#include <of_pci.h>
+
+/**
+ * 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);

include/of_pci.h

@@ -0,0 +1,17 @@
+#ifndef __OF_PCI_H
+#define __OF_PCI_H
+
+#include <linux/pci.h>
+
+#ifdef CONFIG_OF_PCI
+int of_pci_get_devfn(struct device_node *np);
+
+#else
+static inline int of_pci_get_devfn(struct device_node *np)
+{
+	return -EINVAL;
+}
+
+#endif
+
+#endif