[PATCH v5 03/12] dm: core: Add a helper to retrieve devices through graph endpoints

[Svyatoslav Ryhel]

ср, 26 бер. 2025 р. о 17:01 Miquel Raynal <miquel.raynal at bootlin.com> пише:
>
> There are already several helpers to find a udevice based on its
> position in a device tree, like getting a child or a node pointed by a
> phandle, but there was no support for graph endpoints, which are very
> common in display pipelines.
>
> Add a new helper, named uclass_get_device_by_endpoint() which enters the
> child graph reprensentation, looks for a specific port, then follows the
> remote endpoint, and finally retrieves the first parent of the given
> uclass_id.
>
> This is a very handy and straightforward way to get a bridge or a panel
> handle.
>
> Reviewed-by: Simon Glass <sjg at chromium.org>
> Signed-off-by: Miquel Raynal <miquel.raynal at bootlin.com>
> ---
>  drivers/core/uclass.c | 19 +++++++++++++++++++
>  include/dm/uclass.h   | 24 ++++++++++++++++++++++++
>  2 files changed, 43 insertions(+)
>
> diff --git a/drivers/core/uclass.c b/drivers/core/uclass.c
> index f846a35d6b2537bab56bca158cedfb134b37f477..ce5e61bbaa63a181a1ea6781ad6a7f06be67c7e0 100644
> --- a/drivers/core/uclass.c
> +++ b/drivers/core/uclass.c
> @@ -16,6 +16,7 @@
>  #include <dm/device.h>
>  #include <dm/device-internal.h>
>  #include <dm/lists.h>
> +#include <dm/ofnode_graph.h>
>  #include <dm/uclass.h>
>  #include <dm/uclass-internal.h>
>  #include <dm/util.h>
> @@ -582,6 +583,24 @@ int uclass_get_device_by_phandle(enum uclass_id id, struct udevice *parent,
>         ret = uclass_find_device_by_phandle(id, parent, name, &dev);
>         return uclass_get_device_tail(dev, ret, devp);
>  }
> +
> +int uclass_get_device_by_endpoint(enum uclass_id class_id, struct udevice *dev,
> +                                 int port_idx, int ep_idx, struct udevice **devp)
> +{
> +       ofnode node_source = dev_ofnode(dev);
> +       ofnode node_dest = ofnode_graph_get_remote_node(node_source, port_idx, ep_idx);

You may use dev_ofnode(dev) directly instead of node_source if you
wish, but that is up to you.

> +       struct udevice *target = NULL;
> +       int ret;
> +
> +       if (!ofnode_valid(node_dest))
> +               return -EINVAL;
> +
> +       ret = uclass_find_device_by_ofnode(class_id, node_dest, &target);

You can use uclass_get_device_by_ofnode here and avoid using
uclass_get_device_tail later.

> +       if (ret)
> +               return -ENODEV;
> +
> +       return uclass_get_device_tail(target, 0, devp);
> +}
>  #endif
>
>  /*
> diff --git a/include/dm/uclass.h b/include/dm/uclass.h
> index c279304092352200d5297ad2d17f527173ec506b..8fdd72725119aae6ad2b62f4b0c38866a910389c 100644
> --- a/include/dm/uclass.h
> +++ b/include/dm/uclass.h
> @@ -333,6 +333,30 @@ int uclass_get_device_by_phandle(enum uclass_id id, struct udevice *parent,
>  int uclass_get_device_by_driver(enum uclass_id id, const struct driver *drv,
>                                 struct udevice **devp);
>
> +/**
> + * uclass_get_device_by_endpoint() - Get a uclass device for a remote endpoint
> + *
> + * This searches through the parents of the specified remote endpoint
> + * for the first device matching the uclass. Said otherwise, this helper
> + * goes through the graph (endpoint) representation and searches for
> + * matching devices. Endpoints can be subnodes of the "port" node or
> + * subnodes of ports identified with a reg property, themselves in a
> + * "ports" container.
> + *
> + * The device is probed to activate it ready for use.
> + *
> + * @class_id: uclass ID to look up
> + * @dev: Device to start from
> + * @port_idx: Index of the port to follow, -1 if there is a single 'port'
> + *            node without reg.
> + * @ep_idx: Index of the endpoint to follow, -1 if there is a single 'endpoint'
> + *          node without reg.
> + * @target: Returns pointer to the first device matching the expected uclass.
> + * Return: 0 if OK, -ve on error
> + */
> +int uclass_get_device_by_endpoint(enum uclass_id class_id, struct udevice *dev,
> +                                 int port_idx, int ep_idx, struct udevice **target);
> +
>  /**
>   * uclass_first_device() - Get the first device in a uclass
>   *
>
> --
> 2.48.1
>