Re: [PATCH v5 1/5] i3c: master: Expose the APIs to support I3C hub

[Frank Li <Frank.li@nxp.com>]

On Fri, Feb 06, 2026 at 02:01:17PM +0200, Aman Kumar Pandey wrote:
> Expose i3c_master_send_ccc_cmd(), i3c_master_supports_ccc_cmd(),
> i3c_master_reattach_i3c_dev(), i3c_master_direct_attach_i3c_dev(),
> and i3c_master_direct_detach_i3c_dev() to support I3C hub.
>
> Signed-off-by: Aman Kumar Pandey <aman.kumarpandey@nxp.com>
>
> ---
> Changes in v5:
>  - No change
>
> Changes in v4:
>  - Updated I3C master to handle hub support
> ---
> ---
>  drivers/i3c/master.c       | 123 ++++++++++++++++++++++++++++++++++++-
>  include/linux/i3c/master.h |  11 ++++
>  2 files changed, 132 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/i3c/master.c b/drivers/i3c/master.c
> index 7f606c871648..c92152ff795f 100644
> --- a/drivers/i3c/master.c
> +++ b/drivers/i3c/master.c
> @@ -1544,8 +1544,76 @@ static int i3c_master_attach_i3c_dev(struct i3c_master_controller *master,
>  	return 0;
>  }
>
> -static int i3c_master_reattach_i3c_dev(struct i3c_dev_desc *dev,
> -				       u8 old_dyn_addr)
> +/**
> + * i3c_master_direct_attach_i3c_dev() - attach an I3C device to a master
> + * @master: I3C master controller to attach the device to
> + * @dev: I3C device descriptor representing the device
> + *
> + * This function attaches an I3C device to its master controller once the
> + * device has a valid address on the bus. Devices without
> + * an assigned address are ignored. The master device itself is never
> + * attached through this bus.
> + *
> + * Return: 0 on success, or a negative error code if the attach operation
> + *         fails in the master controller driver.
> + */
> +int i3c_master_direct_attach_i3c_dev(struct i3c_master_controller *master,
> +				     struct i3c_dev_desc *dev)
> +{
> +	int ret = 0;
> +
> +	/*
> +	 * We don't attach devices to the controller until they are
> +	 * addressable on the bus.
> +	 */
> +
> +	if (!dev->info.static_addr && !dev->info.dyn_addr)
> +		return 0;

AI: - Silent success on invalid input is questionable - should this be -EINVAL?

> +
> +	/* Do not attach the master device itself. */
> +	if (master->this != dev && master->ops->attach_i3c_dev)
> +		ret = master->ops->attach_i3c_dev(dev);
> +
> +	return ret;
> +}
> +EXPORT_SYMBOL_GPL(i3c_master_direct_attach_i3c_dev);
> +
> +/**
> + * i3c_master_direct_detach_i3c_dev - Detach an I3C device from its master
> + * @dev: I3C device descriptor to be detached
> + *
> + * This function detaches an I3C device from its master controller.
> + * It ensures that the master itself is not detached. If the device is not
> + * the master and the master controller provides a detach operation,
> + * the detach callback is invoked to perform the actual removal.
> + */
> +void i3c_master_direct_detach_i3c_dev(struct i3c_dev_desc *dev)
> +{
> +	struct i3c_master_controller *master = i3c_dev_get_master(dev);
> +
> +	/* Do not detach the master device itself. */
> +	if (master->this != dev && master->ops->detach_i3c_dev)
> +		master->ops->detach_i3c_dev(dev);
> +}
> +EXPORT_SYMBOL_GPL(i3c_master_direct_detach_i3c_dev);

Can you create two patch,
- change existed static function to API.
- add new APIs.

Frank
> +
> +/**
> + * i3c_master_reattach_i3c_dev() - reattach an I3C device with a new address
> + * @dev: I3C device descriptor to reattach
> + * @old_dyn_addr: previous dynamic address of the device
> + *
> + * This function reattaches an existing I3C device to the bus when its dynamic
> + * address has changed. It updates the bus address slot status accordingly:
> + * - Marks the new dynamic address as occupied by an I3C device.
> + * - Frees the old dynamic address slot if applicable.
> + *
> + * This function must be called with the bus lock held in write mode.
> + *
> + * Return: 0 on success, or a negative error code if reattachment fails
> + *         (e.g. -EBUSY if the new address slot is not free).
> + */
> +int i3c_master_reattach_i3c_dev(struct i3c_dev_desc *dev,
> +				u8 old_dyn_addr)
>  {
>  	struct i3c_master_controller *master = i3c_dev_get_master(dev);
>  	int ret;
> @@ -1569,6 +1637,7 @@ static int i3c_master_reattach_i3c_dev(struct i3c_dev_desc *dev,
>
>  	return 0;
>  }
> +EXPORT_SYMBOL_GPL(i3c_master_reattach_i3c_dev);
>
>  static void i3c_master_detach_i3c_dev(struct i3c_dev_desc *dev)
>  {
> @@ -1692,6 +1761,56 @@ i3c_master_register_new_i3c_devs(struct i3c_master_controller *master)
>  	}
>  }
>
> +/**
> + * i3c_master_supports_ccc_cmd() - check CCC command support
> + * @master: I3C master controller
> + * @cmd: CCC command to verify
> + *
> + * This function verifies whether the given I3C master controller supports
> + * the specified Common Command Code (CCC).
> + *
> + * Return: 0 if the CCC command is supported and executed successfully,
> + *         -EINVAL if arguments are invalid,
> + *         -EOPNOTSUPP if the master does not support CCC commands,
> + *         or another negative error code from the master's operation.
> + */
> +int i3c_master_supports_ccc_cmd(struct i3c_master_controller *master,
> +				const struct i3c_ccc_cmd *cmd)
> +{
> +	if (!cmd || !master)
> +		return -EINVAL;
> +
> +	if (!master->ops->supports_ccc_cmd)
> +		return -EOPNOTSUPP;
> +
> +	return master->ops->supports_ccc_cmd(master, cmd);
> +}
> +EXPORT_SYMBOL_GPL(i3c_master_supports_ccc_cmd);
> +
> +/**
> + * i3c_master_send_ccc_cmd() - send a CCC command
> + * @master: I3C master controller issuing the command
> + * @cmd: CCC command to be sent
> + *
> + * This function sends a Common Command Code (CCC) command to devices on the
> + * I3C bus. It acquires the bus maintenance lock, executes the command, and
> + * then releases the lock to ensure safe access to the bus.
> + *
> + * Return: 0 on success, or a negative error code on failure.
> + */
> +int i3c_master_send_ccc_cmd(struct i3c_master_controller *master,
> +			    struct i3c_ccc_cmd *cmd)
> +{
> +	int ret;
> +
> +	i3c_bus_maintenance_lock(&master->bus);
> +	ret = i3c_master_send_ccc_cmd_locked(master, cmd);
> +	i3c_bus_maintenance_unlock(&master->bus);
> +
> +	return ret;
> +}
> +EXPORT_SYMBOL_GPL(i3c_master_send_ccc_cmd);
> +
>  /**
>   * i3c_master_do_daa() - do a DAA (Dynamic Address Assignment)
>   * @master: master doing the DAA
> diff --git a/include/linux/i3c/master.h b/include/linux/i3c/master.h
> index 58d01ed4cce7..b059da7777d7 100644
> --- a/include/linux/i3c/master.h
> +++ b/include/linux/i3c/master.h
> @@ -602,6 +602,17 @@ void i3c_master_dma_unmap_single(struct i3c_dma *dma_xfer);
>  DEFINE_FREE(i3c_master_dma_unmap_single, void *,
>  	    if (_T) i3c_master_dma_unmap_single(_T))
>
> +int i3c_master_send_ccc_cmd(struct i3c_master_controller *master,
> +			    struct i3c_ccc_cmd *cmd);
> +
> +int i3c_master_supports_ccc_cmd(struct i3c_master_controller *master,
> +				const struct i3c_ccc_cmd *cmd);
> +
> +int i3c_master_reattach_i3c_dev(struct i3c_dev_desc *dev,
> +				u8 old_dyn_addr);
> +int i3c_master_direct_attach_i3c_dev(struct i3c_master_controller *master,
> +				     struct i3c_dev_desc *dev);
> +void i3c_master_direct_detach_i3c_dev(struct i3c_dev_desc *dev);
>  int i3c_master_set_info(struct i3c_master_controller *master,
>  			const struct i3c_device_info *info);
>
> --
> 2.25.1
>