[PATCH v5 2/8] media: v4l2-fwnode: Add common helper library for 1-to-1 subdev registration

[Frank.Li@oss.nxp.com]

From: Frank Li <Frank.Li@nxp.com>

Many V4L2 subdev drivers implement the same registration and media pad
setup logic for simple pipelines consisting of a single sink pad and a
single source pad. As a result, the same boilerplate code is duplicated
across multiple drivers.

Introduce a common helper library for 1-to-1 subdevs to encapsulate the
registration, media entity initialization, and cleanup paths. Drivers
can embed a struct v4l2_subdev_1to1 instance and use the provided helper
APIs instead of open-coding the setup sequence.

This reduces code duplication and simplifies the implementation of
simple bridge and converter drivers.

In 1TO1 subdev driver:

struct your_device {
	v4l2_subdev_1to1 sd_1to1; // instead of v4l2_subdev sd;
	...
}
...
your_device_probe()
{
	v4l2_subdev_init(&sd_1to1->sd, &dw_mipi_csi2rx_ops);
	...
	media_async_register_subdev_1to1(sd_1to1);
}

...
your_device_remove()
{
	media_async_subdev_1to1_cleanup();
}

Signed-off-by: Frank Li <Frank.Li@nxp.com>
---
change in v5
- new patch
---
 drivers/media/v4l2-core/Kconfig     |   3 +
 drivers/media/v4l2-core/Makefile    |   1 +
 drivers/media/v4l2-core/v4l2-1to1.c | 117 ++++++++++++++++++++++++++++++++++++
 include/media/v4l2-device-1to1.h    |  72 ++++++++++++++++++++++
 4 files changed, 193 insertions(+)

diff --git a/drivers/media/v4l2-core/Kconfig b/drivers/media/v4l2-core/Kconfig
index d50ccac9733cc..532375cae7947 100644
--- a/drivers/media/v4l2-core/Kconfig
+++ b/drivers/media/v4l2-core/Kconfig
@@ -74,6 +74,9 @@ config V4L2_FWNODE
 config V4L2_ASYNC
 	tristate
 
+config V4L2_1TO1
+	tristate
+
 config V4L2_CCI
 	tristate
 
diff --git a/drivers/media/v4l2-core/Makefile b/drivers/media/v4l2-core/Makefile
index 329f0eadce994..55bf0e6bf2e33 100644
--- a/drivers/media/v4l2-core/Makefile
+++ b/drivers/media/v4l2-core/Makefile
@@ -24,6 +24,7 @@ videodev-$(CONFIG_VIDEO_V4L2_I2C) += v4l2-i2c.o
 # Please keep it alphabetically sorted by Kconfig name
 # (e. g. LC_ALL=C sort Makefile)
 
+obj-$(CONFIG_V4L2_1TO1) += v4l2-1to1.o
 obj-$(CONFIG_V4L2_ASYNC) += v4l2-async.o
 obj-$(CONFIG_V4L2_CCI) += v4l2-cci.o
 obj-$(CONFIG_V4L2_FLASH_LED_CLASS) += v4l2-flash-led-class.o
diff --git a/drivers/media/v4l2-core/v4l2-1to1.c b/drivers/media/v4l2-core/v4l2-1to1.c
new file mode 100644
index 0000000000000..9f23dccece704
--- /dev/null
+++ b/drivers/media/v4l2-core/v4l2-1to1.c
@@ -0,0 +1,117 @@
+// SPDX-License-Identifier: GPL-2.0-only
+
+#include <linux/property.h>
+
+#include <media/v4l2-async.h>
+#include <media/v4l2-device-1to1.h>
+#include <media/v4l2-fwnode.h>
+#include <media/v4l2-mc.h>
+#include <media/v4l2-subdev.h>
+
+static int v4l2_1to1_notifier_bound(struct v4l2_async_notifier *notifier,
+				    struct v4l2_subdev *sd,
+				    struct v4l2_async_connection *asd)
+{
+	struct v4l2_subdev_1to1 *sd_1to1 = v4l2_sd_to_1to1_device(notifier->sd);
+	struct media_pad *sink_pad = &sd_1to1->pads[V4L2_SUBDEV_1TO1_PADS_SINK];
+	int ret;
+
+	ret = v4l2_create_fwnode_links_to_pad(sd, sink_pad, MEDIA_LNK_FL_ENABLED);
+	if (ret) {
+		dev_err(sd_1to1->sd.dev, "failed to link source pad of %s\n", sd->name);
+		return ret;
+	}
+
+	return 0;
+}
+
+static const struct v4l2_async_notifier_operations v4l2_1to1_notifier_ops = {
+	.bound = v4l2_1to1_notifier_bound,
+};
+
+static int
+v4l2_async_nf_parse_fwnode_1to1(struct device *dev, struct v4l2_async_notifier *notifier)
+{
+	struct v4l2_subdev *sd = notifier->sd;
+	struct v4l2_subdev_1to1 *sd_1to1 = v4l2_sd_to_1to1_device(sd);
+	struct v4l2_fwnode_endpoint *vep = &sd_1to1->vep;
+	struct v4l2_async_connection *asd;
+	int ret;
+
+	struct fwnode_handle *ep __free(fwnode_handle) =
+		fwnode_graph_get_endpoint_by_id(dev_fwnode(dev), 0, 0, 0);
+	if (!ep)
+		return dev_err_probe(dev, -ENODEV, "failed to get endpoint\n");
+
+	ret = v4l2_fwnode_endpoint_parse(ep, vep);
+	if (ret)
+		return dev_err_probe(dev, ret, "failed to parse endpoint\n");
+
+	if (!(BIT(vep->bus_type) & sd_1to1->remote_bustype_cap_mask))
+		return dev_err_probe(dev, -EINVAL,
+				     "invalid bus type %d of endpoint\n",
+				     vep->bus_type);
+
+	notifier->ops = &v4l2_1to1_notifier_ops;
+
+	asd = v4l2_async_nf_add_fwnode_remote(notifier, ep,
+					      struct v4l2_async_connection);
+	if (IS_ERR(asd))
+		return dev_err_probe(dev, PTR_ERR(asd),
+				     "failed to add notifier\n");
+
+	return 0;
+}
+
+void media_async_subdev_1to1_cleanup(struct v4l2_subdev_1to1 *sd_1to1)
+{
+	struct v4l2_subdev *sd = &sd_1to1->sd;
+
+	v4l2_async_unregister_subdev(sd);
+	v4l2_subdev_cleanup(sd);
+	media_entity_cleanup(&sd->entity);
+	v4l2_async_nf_unregister(sd->subdev_notifier);
+	v4l2_async_nf_cleanup(sd->subdev_notifier);
+
+	kfree(sd->subdev_notifier);
+}
+EXPORT_SYMBOL_GPL(media_async_subdev_1to1_cleanup);
+
+int __media_async_register_subdev_1to1(struct v4l2_subdev_1to1 *sd_1to1, struct module *module)
+{
+	struct media_pad *pads = sd_1to1->pads;
+	int ret;
+
+	pads[V4L2_SUBDEV_1TO1_PADS_SINK].flags = MEDIA_PAD_FL_SINK |
+					       MEDIA_PAD_FL_MUST_CONNECT;
+	pads[V4L2_SUBDEV_1TO1_PADS_SOURCE].flags = MEDIA_PAD_FL_SOURCE |
+						 MEDIA_PAD_FL_MUST_CONNECT;
+
+	ret = media_entity_pads_init(&sd_1to1->sd.entity, V4L2_SUBDEV_1TO1_PADS_TOTAL, pads);
+	if (ret)
+		return ret;
+
+	ret = v4l2_subdev_init_finalize(&sd_1to1->sd);
+	if (ret)
+		goto err_entity_cleanup;
+
+	ret = __v4l2_async_register_subdev_fwnode(&sd_1to1->sd,
+						  v4l2_async_nf_parse_fwnode_1to1,
+						  module);
+	if (ret)
+		goto err_subdev_cleanup;
+
+	return 0;
+
+err_subdev_cleanup:
+	v4l2_subdev_cleanup(&sd_1to1->sd);
+err_entity_cleanup:
+	media_entity_cleanup(&sd_1to1->sd.entity);
+
+	return ret;
+}
+EXPORT_SYMBOL_GPL(__media_async_register_subdev_1to1);
+
+MODULE_DESCRIPTION("V4L2 subdev 1to1 helper library");
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Frank.Li@kernel.org");
diff --git a/include/media/v4l2-device-1to1.h b/include/media/v4l2-device-1to1.h
new file mode 100644
index 0000000000000..a1256767b4d4c
--- /dev/null
+++ b/include/media/v4l2-device-1to1.h
@@ -0,0 +1,72 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+#ifndef __V4L2_SUBDEV_1TO1__
+#define __V4L2_SUBDEV_1TO1__
+
+#include <media/media-entity.h>
+#include <media/v4l2-fwnode.h>
+#include <media/v4l2-subdev.h>
+
+enum v4l2_subdev_1to1_pads {
+	V4L2_SUBDEV_1TO1_PADS_SINK,
+	V4L2_SUBDEV_1TO1_PADS_SOURCE,
+	V4L2_SUBDEV_1TO1_PADS_TOTAL,
+};
+
+/**
+ * struct v4l2_subdev_1to1 - 1to1 sub-device
+ *
+ * @sd:         sub-device that registered the notifier, NULL otherwise
+ * @pads:	media pads(the first one is sink, the second one is source)
+ * @vep:	The V4L2 fwnode data structure for remote node.
+ * @remote_bustype_cap_mask:  Bit mask for required remote node v4l2_mbus_type.
+ */
+struct v4l2_subdev_1to1 {
+	struct v4l2_subdev sd;
+	struct media_pad pads[V4L2_SUBDEV_1TO1_PADS_TOTAL];
+	struct v4l2_fwnode_endpoint vep;
+	/* bit masks for enum v4l2_mbus_type*/
+	u32 remote_bustype_cap_mask;
+};
+
+static inline struct v4l2_subdev_1to1 *
+v4l2_sd_to_1to1_device(struct v4l2_subdev *sd)
+{
+	return container_of(sd, struct v4l2_subdev_1to1, sd);
+}
+
+/**
+ * media_async_register_subdev_1to1 - registers a 1to1 sub-device to the
+ *                                    asynchronous sub-device framework and
+ *                                    parse set up common 1to1 related
+ *                                    devices
+ *
+ * @sd_1to1: pointer to struct &v4l2_subdev_1to1
+ *
+ * This function is just like v4l2_async_register_subdev() with the exception
+ * that calling it will also parse firmware interfaces for remote references
+ * using v4l2_async_nf_parse_fwnode_sensor() and registers the
+ * async sub-devices.
+ *
+ * This function also init media_pads.
+ *
+ * The sub-device is similarly unregistered and cleanup by
+ * media_async_subdev_1to1_cleanup()
+ *
+ * While registered, the subdev module is marked as in-use.
+ *
+ * An error is returned if the module is no longer loaded on any attempts
+ * to register it.
+ */
+#define media_async_register_subdev_1to1(sd_1to1) \
+	__media_async_register_subdev_1to1(sd_1to1, THIS_MODULE)
+
+int __media_async_register_subdev_1to1(struct v4l2_subdev_1to1 *sd_1to1, struct module *module);
+
+/**
+ * media_async_subdev_1to1_cleanup - unregistered and cleanup subdev and media
+ *				     pads
+ * @sd_1to1: pointer to struct &v4l2_subdev_1to1
+ */
+void media_async_subdev_1to1_cleanup(struct v4l2_subdev_1to1 *sd_1to1);
+
+#endif

-- 
2.43.0