drm/i915/icl: introduce tc_port

Add and enum for TC ports and auxiliary functions to handle them.
Icelake brings a lot of registers and other things that only apply to
the TC ports and are indexed starting from 0, so having an enum for
tc_ports that starts at 0 really helps the indexing.

This patch is based on previous patches written by Dhinakaran Pandiyan
and Mahesh Kumar.

Cc: Dhinakaran Pandiyan <dhinakaran.pandiyan@intel.com>
Cc: Mahesh Kumar <mahesh1.kumar@intel.com>
Reviewed-by: NMahesh Kumar <mahesh1.kumar@intel.com>
Signed-off-by: NPaulo Zanoni <paulo.r.zanoni@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20180522002558.29262-4-paulo.r.zanoni@intel.com

drivers/gpu/drm/i915/intel_display.c

@@ -5869,6 +5869,22 @@ static void i9xx_pfit_enable(struct intel_crtc *crtc)
 	I915_WRITE(BCLRPAT(crtc->pipe), 0);
 }
 
+bool intel_port_is_tc(struct drm_i915_private *dev_priv, enum port port)
+{
+	if (IS_ICELAKE(dev_priv))
+		return port >= PORT_C && port <= PORT_F;
+
+	return false;
+}
+
+enum tc_port intel_port_to_tc(struct drm_i915_private *dev_priv, enum port port)
+{
+	if (!intel_port_is_tc(dev_priv, port))
+		return PORT_TC_NONE;
+
+	return port - PORT_C;
+}
+
 enum intel_display_power_domain intel_port_to_power_domain(enum port port)
 {
 	switch (port) {

drivers/gpu/drm/i915/intel_display.h

@@ -126,6 +126,17 @@ enum port {
 
 #define port_name(p) ((p) + 'A')
 
+enum tc_port {
+	PORT_TC_NONE = -1,
+
+	PORT_TC1 = 0,
+	PORT_TC2,
+	PORT_TC3,
+	PORT_TC4,
+
+	I915_MAX_TC_PORTS
+};
+
 enum dpio_channel {
 	DPIO_CH0,
 	DPIO_CH1

drivers/gpu/drm/i915/intel_drv.h

@@ -1489,6 +1489,9 @@ void intel_connector_attach_encoder(struct intel_connector *connector,
 				    struct intel_encoder *encoder);
 struct drm_display_mode *
 intel_encoder_current_mode(struct intel_encoder *encoder);
+bool intel_port_is_tc(struct drm_i915_private *dev_priv, enum port port);
+enum tc_port intel_port_to_tc(struct drm_i915_private *dev_priv,
+			      enum port port);
 
 enum pipe intel_get_pipe_from_connector(struct intel_connector *connector);
 int intel_get_pipe_from_crtc_id_ioctl(struct drm_device *dev, void *data,