drm/i915: add enumeration for DDI ports

There are 5 DDI ports on Haswell. Port A is always enabled, and is the one
connected to eDP, and Port E is the one that can be connected to the PCH
using FDI protocol.  Ports B, C, D and E can be used for digital outputs.

Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: Eugeni Dodonov <eugeni.dodonov@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

drivers/gpu/drm/i915/i915_drv.h

@@ -63,6 +63,16 @@ enum plane {
 };
 #define plane_name(p) ((p) + 'A')
 
+enum port {
+	PORT_A = 0,
+	PORT_B,
+	PORT_C,
+	PORT_D,
+	PORT_E,
+	I915_MAX_PORTS
+};
+#define port_name(p) ((p) + 'A')
+
 #define I915_GEM_GPU_DOMAINS	(~(I915_GEM_DOMAIN_CPU | I915_GEM_DOMAIN_GTT))
 
 #define for_each_pipe(p) for ((p) = 0; (p) < dev_priv->num_pipe; (p)++)

drivers/gpu/drm/i915/i915_reg.h

@@ -27,6 +27,8 @@
 
 #define _PIPE(pipe, a, b) ((a) + (pipe)*((b)-(a)))
 
+#define _PORT(port, a, b) ((a) + (port)*((b)-(a)))
+
 /*
  * The Bridge device's PCI config space has information about the
  * fb aperture size and the amount of pre-reserved memory.