UPSTREAM: of/pci: Add helper function to parse max-link-speed from dt

[firefly-linux-kernel-4.4.55.git] / drivers / of / of_pci.c

diff --git a/drivers/of/of_pci.c b/drivers/of/of_pci.c
index b1449f71601cb257f1057b77c217a943da92cab8..038c0ec1b0c523b6d2a191f1476d9684efc270c7 100644 (file)
--- a/drivers/of/of_pci.c
+++ b/drivers/of/of_pci.c
@@ -118,6 +118,27 @@ int of_get_pci_domain_nr(struct device_node *node)
 }
 EXPORT_SYMBOL_GPL(of_get_pci_domain_nr);
 
+/**
+ * This function will try to find the limitation of link speed by finding
+ * a property called "max-link-speed" of the given device node.
+ *
+ * @node: device tree node with the max link speed information
+ *
+ * Returns the associated max link speed from DT, or a negative value if the
+ * required property is not found or is invalid.
+ */
+int of_pci_get_max_link_speed(struct device_node *node)
+{
+       u32 max_link_speed;
+
+       if (of_property_read_u32(node, "max-link-speed", &max_link_speed) ||
+           max_link_speed > 4)
+               return -EINVAL;
+
+       return max_link_speed;
+}
+EXPORT_SYMBOL_GPL(of_pci_get_max_link_speed);
+
 /**
  * of_pci_check_probe_only - Setup probe only mode if linux,pci-probe-only
  *                           is present and valid