drm/exynos: Implement lvds bridge discovery to DP driver

This patch implements the lvds bridge discovery and connector pre-emption
code to the dp driver.

Signed-off-by: Sean Paul <seanpaul@chromium.org>
Signed-off-by: Inki Dae <inki.dae@samsung.com>

drivers/gpu/drm/exynos/exynos_dp_core.c

@@ -25,13 +25,19 @@
 #include <drm/drmP.h>
 #include <drm/drm_crtc.h>
 #include <drm/drm_crtc_helper.h>
+#include <drm/bridge/ptn3460.h>
 
 #include "exynos_drm_drv.h"
 #include "exynos_dp_core.h"
 
 #define ctx_from_connector(c)	container_of(c, struct exynos_dp_device, \
 					connector)
 
+struct bridge_init {
+	struct i2c_client *client;
+	struct device_node *node;
+};
+
 static int exynos_dp_init_dp(struct exynos_dp_device *dp)
 {
 	exynos_dp_reset(dp);
@@ -973,6 +979,35 @@ static int exynos_dp_initialize(struct exynos_drm_display *display,
 	return 0;
 }
 
+static bool find_bridge(const char *compat, struct bridge_init *bridge)
+{
+	bridge->client = NULL;
+	bridge->node = of_find_compatible_node(NULL, NULL, compat);
+	if (!bridge->node)
+		return false;
+
+	bridge->client = of_find_i2c_device_by_node(bridge->node);
+	if (!bridge->client)
+		return false;
+
+	return true;
+}
+
+/* returns the number of bridges attached */
+static int exynos_drm_attach_lcd_bridge(struct drm_device *dev,
+		struct drm_encoder *encoder)
+{
+	struct bridge_init bridge;
+	int ret;
+
+	if (find_bridge("nxp,ptn3460", &bridge)) {
+		ret = ptn3460_init(dev, encoder, bridge.client, bridge.node);
+		if (!ret)
+			return 1;
+	}
+	return 0;
+}
+
 static int exynos_dp_create_connector(struct exynos_drm_display *display,
 				struct drm_encoder *encoder)
 {
@@ -981,6 +1016,12 @@ static int exynos_dp_create_connector(struct exynos_drm_display *display,
 	int ret;
 
 	dp->encoder = encoder;
+
+	/* Pre-empt DP connector creation if there's a bridge */
+	ret = exynos_drm_attach_lcd_bridge(dp->drm_dev, encoder);
+	if (ret)
+		return 0;
+
 	connector->polled = DRM_CONNECTOR_POLL_HPD;
 
 	ret = drm_connector_init(dp->drm_dev, connector,