linux-kernel - Re: [PATCH v2 04/10] serdev: Add an API to find the serdev controller associated with the devicetree node

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Message-ID: <CAMRc=MeOfpFME0LL+WDSM3ZVUOiqTCHQN-E3=PZ_qTMLWDKaKQ@mail.gmail.com>
Date: Thu, 27 Nov 2025 07:52:58 -0600
From: Bartosz Golaszewski <brgl@...ev.pl>
To: manivannan.sadhasivam@....qualcomm.com
Cc: Manivannan Sadhasivam via B4 Relay <devnull+manivannan.sadhasivam.oss.qualcomm.com@...nel.org>, 
	linux-serial@...r.kernel.org, linux-kernel@...r.kernel.org, 
	linux-kbuild@...r.kernel.org, platform-driver-x86@...r.kernel.org, 
	linux-pci@...r.kernel.org, devicetree@...r.kernel.org, 
	linux-arm-msm@...r.kernel.org, linux-bluetooth@...r.kernel.org, 
	linux-pm@...r.kernel.org, Stephan Gerhold <stephan.gerhold@...aro.org>, 
	Dmitry Baryshkov <dmitry.baryshkov@....qualcomm.com>, Rob Herring <robh@...nel.org>, 
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>, Jiri Slaby <jirislaby@...nel.org>, 
	Nathan Chancellor <nathan@...nel.org>, Nicolas Schier <nicolas.schier@...ux.dev>, 
	Hans de Goede <hansg@...nel.org>, Ilpo Järvinen <ilpo.jarvinen@...ux.intel.com>, 
	Mark Pearson <mpearson-lenovo@...ebb.ca>, "Derek J. Clark" <derekjohn.clark@...il.com>, 
	Manivannan Sadhasivam <mani@...nel.org>, Krzysztof Kozlowski <krzk+dt@...nel.org>, Conor Dooley <conor+dt@...nel.org>, 
	Marcel Holtmann <marcel@...tmann.org>, Luiz Augusto von Dentz <luiz.dentz@...il.com>, 
	Bartosz Golaszewski <brgl@...ev.pl>
Subject: Re: [PATCH v2 04/10] serdev: Add an API to find the serdev controller
 associated with the devicetree node

On Tue, 25 Nov 2025 15:45:08 +0100, Manivannan Sadhasivam via B4 Relay
<devnull+manivannan.sadhasivam.oss.qualcomm.com@...nel.org> said:
> From: Manivannan Sadhasivam <manivannan.sadhasivam@....qualcomm.com>
>
> Add of_find_serdev_controller_by_node() API to find the serdev controller
> device associated with the devicetree node.
>
> Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@....qualcomm.com>
> ---
>  drivers/tty/serdev/core.c | 16 ++++++++++++++++
>  include/linux/serdev.h    |  9 +++++++++
>  2 files changed, 25 insertions(+)
>
> diff --git a/drivers/tty/serdev/core.c b/drivers/tty/serdev/core.c
> index 76b89dd0720f..f90095cb778f 100644
> --- a/drivers/tty/serdev/core.c
> +++ b/drivers/tty/serdev/core.c
> @@ -530,6 +530,22 @@ struct serdev_controller *serdev_controller_alloc(struct device *host,
>  }
>  EXPORT_SYMBOL_GPL(serdev_controller_alloc);
>
> +/**
> + * 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.
> + */
> +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);
> +
>  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 ffc6eb13f44b..fa235c92592a 100644
> --- a/include/linux/serdev.h
> +++ b/include/linux/serdev.h
> @@ -337,4 +337,13 @@ static inline bool serdev_acpi_get_uart_resource(struct acpi_resource *ares,
>  }
>  #endif /* CONFIG_ACPI */
>
> +#ifdef CONFIG_OF

You can make it independent from OF if you base the code on fwnode like:

struct serdev_controller find_serdev_controller_by_fwnode(struct
fwnode_handle *fwnode);
{
	struct device *dev = bus_find_device_by_fwnode(&serdev_bus_type, node);

	(...)
}

Users can always convert OF nodes to firmware nodes.

Bart

> +struct serdev_controller *of_find_serdev_controller_by_node(struct device_node *node);
> +#else
> +struct serdev_controller *of_find_serdev_controller_by_node(struct device_node *node)
> +{
> +	return NULL;
> +}
> +#endif /* CONFIG_OF */
> +
>  #endif /*_LINUX_SERDEV_H */
>
> --
> 2.48.1
>
>