Re: [PATCH v5 2/9] serdev: Add an API to find the serdev controller associated with the devicetree node

[Bartosz Golaszewski <brgl@kernel.org>]

On Tue, 24 Feb 2026 06:30:48 +0100, Manivannan Sadhasivam via B4 Relay
<devnull+manivannan.sadhasivam.oss.qualcomm.com@kernel.org> said:
> From: Manivannan Sadhasivam <manivannan.sadhasivam@oss.qualcomm.com>
>
> Add of_find_serdev_controller_by_node() API to find the serdev controller
> device associated with the devicetree node.
>
> Tested-by: Hans de Goede <johannes.goede@oss.qualcomm.com> # ThinkPad T14s gen6 (arm64)
> Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@oss.qualcomm.com>
> ---
>  drivers/tty/serdev/core.c | 19 +++++++++++++++++++
>  include/linux/serdev.h    |  9 +++++++++
>  2 files changed, 28 insertions(+)
>
> diff --git a/drivers/tty/serdev/core.c b/drivers/tty/serdev/core.c
> index 8f25510f89b6..bf88b95f7458 100644
> --- a/drivers/tty/serdev/core.c
> +++ b/drivers/tty/serdev/core.c
> @@ -514,6 +514,25 @@ struct serdev_controller *serdev_controller_alloc(struct device *host,
>  }
>  EXPORT_SYMBOL_GPL(serdev_controller_alloc);
>
> +#ifdef CONFIG_OF
> +/**
> + * of_find_serdev_controller_by_node() - Find the serdev controller associated
> + *					 with the devicetree node
> + * @node:	Devicetree node
> + *
> + * Return: Pointer to the serdev controller associated with the node. NULL if
> + * the controller is not found. Caller is responsible for calling
> + * serdev_controller_put() to drop the reference.
> + */
> +struct serdev_controller *of_find_serdev_controller_by_node(struct device_node *node)
> +{
> +	struct device *dev = bus_find_device_by_of_node(&serdev_bus_type, node);
> +
> +	return (dev && dev->type == &serdev_ctrl_type) ? to_serdev_controller(dev) : NULL;
> +}
> +EXPORT_SYMBOL_GPL(of_find_serdev_controller_by_node);

I'm not sure if I commented on it before but there's no reason for this to be
OF-centric. It would work equally well as (I think the same should keep the
"serdev" prefix too for correct namespacing):

struct serdev_controller *serdev_find_controller_by_fwnode(struct
fwnode_handle *fwnode)
{
	struct device *dev = bus_find_device_by_fwnode();

	...
}

It would be more flexible and users can always use to_of_node().

Bart

> +#endif
> +
>  static int of_serdev_register_devices(struct serdev_controller *ctrl)
>  {
>  	struct device_node *node;
> diff --git a/include/linux/serdev.h b/include/linux/serdev.h
> index 0c7d3c27d1f8..188c0ba62d50 100644
> --- a/include/linux/serdev.h
> +++ b/include/linux/serdev.h
> @@ -334,4 +334,13 @@ static inline bool serdev_acpi_get_uart_resource(struct acpi_resource *ares,
>  }
>  #endif /* CONFIG_ACPI */
>
> +#ifdef CONFIG_OF
> +struct serdev_controller *of_find_serdev_controller_by_node(struct device_node *node);
> +#else
> +static inline struct serdev_controller *of_find_serdev_controller_by_node(struct device_node *node)
> +{
> +	return NULL;
> +}
> +#endif /* CONFIG_OF */
> +
>  #endif /*_LINUX_SERDEV_H */
>
> --
> 2.51.0
>
>
>