of/pci: Add of_pci_parse_bus_range() function

This function can be used to parse a bus-range property as specified by
device nodes representing PCI bridges.

Signed-off-by: Thierry Reding <thierry.reding@avionic-design.de>
Signed-off-by: Jason Cooper <jason@lakedaemon.net>

2 files changed, 26 insertions, 0 deletions

diff --git a/drivers/of/of_pci.c b/drivers/of/of_pci.c
index 4dd7b9b80076..42c687a820ac 100644
--- a/drivers/of/of_pci.c
+++ b/drivers/of/of_pci.c
@@ -64,3 +64,28 @@ int of_pci_get_devfn(struct device_node *np)
         return (be32_to_cpup(reg) >> 8) & 0xff;
 }
 EXPORT_SYMBOL_GPL(of_pci_get_devfn);
+
+/**
+ * of_pci_parse_bus_range() - parse the bus-range property of a PCI device
+ * @node: device node
+ * @res: address to a struct resource to return the bus-range
+ *
+ * Returns 0 on success or a negative error-code on failure.
+ */
+int of_pci_parse_bus_range(struct device_node *node, struct resource *res)
+{
+        const __be32 *values;
+        int len;
+
+        values = of_get_property(node, "bus-range", &len);
+        if (!values || len < sizeof(*values) * 2)
+                return -EINVAL;
+
+        res->name = node->name;
+        res->start = be32_to_cpup(values++);
+        res->end = be32_to_cpup(values);
+        res->flags = IORESOURCE_BUS;
+
+        return 0;
+}
+EXPORT_SYMBOL_GPL(of_pci_parse_bus_range);
diff --git a/include/linux/of_pci.h b/include/linux/of_pci.h
index 91ec484e0045..7a04826018c0 100644
--- a/include/linux/of_pci.h
+++ b/include/linux/of_pci.h
@@ -11,5 +11,6 @@ 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);
+int of_pci_parse_bus_range(struct device_node *node, struct resource *res);
 
 #endif