drm/i915: Introduce a get_aux_send_ctl() vfunc

We need a bit more flexibility here in the future, bits get shuffled
around.

v2: more descriptive commit message (Jani Nikula)
Reviewed-by: Jani Nikula <jani.nikula@intel.com>
Signed-off-by: Damien Lespiau <damien.lespiau@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

drivers/gpu/drm/i915/intel_dp.c

@@ -493,10 +493,10 @@ intel_dp_aux_ch(struct intel_dp *intel_dp,
 	}
 
 	while ((aux_clock_divider = intel_dp->get_aux_clock_divider(intel_dp, clock++))) {
-		u32 send_ctl = i9xx_get_aux_send_ctl(intel_dp,
-						     has_aux_irq,
-						     send_bytes,
-						     aux_clock_divider);
+		u32 send_ctl = intel_dp->get_aux_send_ctl(intel_dp,
+							  has_aux_irq,
+							  send_bytes,
+							  aux_clock_divider);
 
 		/* Must try at least 3 times according to DP spec */
 		for (try = 0; try < 5; try++) {
@@ -3724,6 +3724,8 @@ intel_dp_init_connector(struct intel_digital_port *intel_dig_port,
 	else
 		intel_dp->get_aux_clock_divider = i9xx_get_aux_clock_divider;
 
+	intel_dp->get_aux_send_ctl = i9xx_get_aux_send_ctl;
+
 	/* Preserve the current hw state. */
 	intel_dp->DP = I915_READ(intel_dp->output_reg);
 	intel_dp->attached_connector = intel_connector;

drivers/gpu/drm/i915/intel_drv.h

@@ -495,6 +495,14 @@ struct intel_dp {
 	struct intel_connector *attached_connector;
 
 	uint32_t (*get_aux_clock_divider)(struct intel_dp *dp, int index);
+	/*
+	 * This function returns the value we have to program the AUX_CTL
+	 * register with to kick off an AUX transaction.
+	 */
+	uint32_t (*get_aux_send_ctl)(struct intel_dp *dp,
+				     bool has_aux_irq,
+				     int send_bytes,
+				     uint32_t aux_clock_divider);
 };
 
 struct intel_digital_port {