drm: xlnx: zynqmp_dpsub: Parse DT to find connected ports

To prepare for live video input support, parse the device tree to find
the connected ports. Warn about unsupported configurations, and error
out when invalid.
Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>

drivers/gpu/drm/xlnx/zynqmp_dpsub.c

@@ -12,6 +12,7 @@
 #include <linux/clk.h>
 #include <linux/dma-mapping.h>
 #include <linux/module.h>
+#include <linux/of_graph.h>
 #include <linux/of_reserved_mem.h>
 #include <linux/platform_device.h>
 #include <linux/pm_runtime.h>
@@ -142,6 +143,55 @@ static int zynqmp_dpsub_init_clocks(struct zynqmp_dpsub *dpsub)
 	return 0;
 }
 
+static int zynqmp_dpsub_parse_dt(struct zynqmp_dpsub *dpsub)
+{
+	struct device_node *np;
+	unsigned int i;
+
+	/*
+	 * For backward compatibility with old device trees that don't contain
+	 * ports, consider that only the DP output port is connected if no
+	 * ports child no exists.
+	 */
+	np = of_get_child_by_name(dpsub->dev->of_node, "ports");
+	of_node_put(np);
+	if (!np) {
+		dev_warn(dpsub->dev, "missing ports, update DT bindings\n");
+		dpsub->connected_ports = BIT(ZYNQMP_DPSUB_PORT_OUT_DP);
+		return 0;
+	}
+
+	/* Check which ports are connected. */
+	for (i = 0; i < ZYNQMP_DPSUB_NUM_PORTS; ++i) {
+		struct device_node *np;
+
+		np = of_graph_get_remote_node(dpsub->dev->of_node, i, -1);
+		if (np) {
+			dpsub->connected_ports |= BIT(i);
+			of_node_put(np);
+		}
+	}
+
+	/* Sanity checks. */
+	if ((dpsub->connected_ports & BIT(ZYNQMP_DPSUB_PORT_LIVE_VIDEO)) ||
+	    (dpsub->connected_ports & BIT(ZYNQMP_DPSUB_PORT_LIVE_GFX)))
+		dev_warn(dpsub->dev, "live video unsupported, ignoring\n");
+
+	if (dpsub->connected_ports & BIT(ZYNQMP_DPSUB_PORT_LIVE_AUDIO))
+		dev_warn(dpsub->dev, "live audio unsupported, ignoring\n");
+
+	if ((dpsub->connected_ports & BIT(ZYNQMP_DPSUB_PORT_OUT_VIDEO)) ||
+	    (dpsub->connected_ports & BIT(ZYNQMP_DPSUB_PORT_OUT_AUDIO)))
+		dev_warn(dpsub->dev, "output to PL unsupported, ignoring\n");
+
+	if (!(dpsub->connected_ports & BIT(ZYNQMP_DPSUB_PORT_OUT_DP))) {
+		dev_err(dpsub->dev, "DP output port not connected\n");
+		return -EINVAL;
+	}
+
+	return 0;
+}
+
 void zynqmp_dpsub_release(struct zynqmp_dpsub *dpsub)
 {
 	kfree(dpsub->disp);
@@ -171,6 +221,10 @@ static int zynqmp_dpsub_probe(struct platform_device *pdev)
 	if (ret < 0)
 		goto err_mem;
 
+	ret = zynqmp_dpsub_parse_dt(dpsub);
+	if (ret < 0)
+		goto err_mem;
+
 	pm_runtime_enable(&pdev->dev);
 
 	/*

drivers/gpu/drm/xlnx/zynqmp_dpsub.h

@@ -22,6 +22,16 @@ struct zynqmp_dpsub_drm;
 
 #define ZYNQMP_DPSUB_NUM_LAYERS				2
 
+enum zynqmp_dpsub_port {
+	ZYNQMP_DPSUB_PORT_LIVE_VIDEO,
+	ZYNQMP_DPSUB_PORT_LIVE_GFX,
+	ZYNQMP_DPSUB_PORT_LIVE_AUDIO,
+	ZYNQMP_DPSUB_PORT_OUT_VIDEO,
+	ZYNQMP_DPSUB_PORT_OUT_AUDIO,
+	ZYNQMP_DPSUB_PORT_OUT_DP,
+	ZYNQMP_DPSUB_NUM_PORTS,
+};
+
 enum zynqmp_dpsub_format {
 	ZYNQMP_DPSUB_FORMAT_RGB,
 	ZYNQMP_DPSUB_FORMAT_YCRCB444,
@@ -37,6 +47,7 @@ enum zynqmp_dpsub_format {
  * @vid_clk_from_ps: True of the video clock comes from PS, false from PL
  * @aud_clk: Audio clock
  * @aud_clk_from_ps: True of the audio clock comes from PS, false from PL
+ * @connected_ports: Bitmask of connected ports in the device tree
  * @drm: The DRM/KMS device data
  * @bridge: The DP encoder bridge
  * @disp: The display controller
@@ -52,6 +63,8 @@ struct zynqmp_dpsub {
 	struct clk *aud_clk;
 	bool aud_clk_from_ps;
 
+	unsigned int connected_ports;
+
 	struct zynqmp_dpsub_drm *drm;
 	struct drm_bridge *bridge;