[PATCH v6 5/6] media: sun6i-csi: Detect the availability of the ISP

[Paul Kocialkowski <paul.kocialkowski@xxxxxxxxxxx>]

Add a helper to detect whether the ISP is available and connected
and store the indication in a driver-wide variable.

Signed-off-by: Paul Kocialkowski <paul.kocialkowski@xxxxxxxxxxx>
---
 .../platform/sunxi/sun6i-csi/sun6i_csi.c      | 33 +++++++++++++++++++
 .../platform/sunxi/sun6i-csi/sun6i_csi.h      |  3 ++
 2 files changed, 36 insertions(+)

diff --git a/drivers/media/platform/sunxi/sun6i-csi/sun6i_csi.c b/drivers/media/platform/sunxi/sun6i-csi/sun6i_csi.c
index 00521f966cee..b16166cba2ef 100644
--- a/drivers/media/platform/sunxi/sun6i-csi/sun6i_csi.c
+++ b/drivers/media/platform/sunxi/sun6i-csi/sun6i_csi.c
@@ -24,6 +24,35 @@
 #include "sun6i_csi_capture.h"
 #include "sun6i_csi_reg.h"
 
+/* ISP */
+
+static bool sun6i_csi_isp_detect(struct sun6i_csi_device *csi_dev)
+{
+	struct device *dev = csi_dev->dev;
+	struct fwnode_handle *handle = NULL;
+
+	/* ISP is not available if disabled in kernel config. */
+	if (!IS_ENABLED(CONFIG_VIDEO_SUN6I_ISP))
+		return 0;
+
+	/*
+	 * ISP is not available if not connected via fwnode graph.
+	 * This weill also check that the remote parent node is available.
+	 */
+	handle = fwnode_graph_get_endpoint_by_id(dev_fwnode(dev),
+						 SUN6I_CSI_PORT_ISP, 0,
+						 FWNODE_GRAPH_ENDPOINT_NEXT);
+	if (!handle)
+		return 0;
+
+	fwnode_handle_put(handle);
+
+	dev_info(dev, "ISP link is available\n");
+	csi_dev->isp_available = true;
+
+	return 0;
+}
+
 /* Media */
 
 static const struct media_device_ops sun6i_csi_media_ops = {
@@ -290,6 +319,10 @@ static int sun6i_csi_probe(struct platform_device *platform_dev)
 	if (ret)
 		return ret;
 
+	ret = sun6i_csi_isp_detect(csi_dev);
+	if (ret)
+		goto error_resources;
+
 	ret = sun6i_csi_v4l2_setup(csi_dev);
 	if (ret)
 		goto error_resources;
diff --git a/drivers/media/platform/sunxi/sun6i-csi/sun6i_csi.h b/drivers/media/platform/sunxi/sun6i-csi/sun6i_csi.h
index e611bdd6e9b2..8e232cd91ebe 100644
--- a/drivers/media/platform/sunxi/sun6i-csi/sun6i_csi.h
+++ b/drivers/media/platform/sunxi/sun6i-csi/sun6i_csi.h
@@ -21,6 +21,7 @@
 enum sun6i_csi_port {
 	SUN6I_CSI_PORT_PARALLEL		= 0,
 	SUN6I_CSI_PORT_MIPI_CSI2	= 1,
+	SUN6I_CSI_PORT_ISP		= 2,
 };
 
 struct sun6i_csi_buffer {
@@ -44,6 +45,8 @@ struct sun6i_csi_device {
 	struct clk			*clock_mod;
 	struct clk			*clock_ram;
 	struct reset_control		*reset;
+
+	bool				isp_available;
 };
 
 struct sun6i_csi_variant {
-- 
2.37.1