Re: [PATCH v6 1/7] i3c: master: Expose the APIs to support I3C hub

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

On Tue, Mar 10, 2026 at 12:27:21PM +0530, Lakshay Piplani wrote:
> From: Aman Kumar Pandey <aman.kumarpandey@nxp.com>
>
> Expose the below APIs to support I3C hub.
>
> 1) i3c_dev_enable_ibi_locked()
> 2) i3c_dev_disable_ibi_locked()
> 3) i3c_dev_request_ibi_locked()
> 4) i3c_dev_free_ibi_locked()
> 5) i3c_master_reattach_i3c_dev()
>
> Signed-off-by: Aman Kumar Pandey <aman.kumarpandey@nxp.com>
>
> ---
> Changes in v6:
>  - Split the patch into two parts:
>         1) expose the existing API
>         2) add new APIs.
>
> Changes in v5:
>  - No change
>
> Changes in v4:
>  - Updated I3C master to handle hub support
> ---
> ---
>  drivers/i3c/master.c       | 70 ++++++++++++++++++++++++++++++++++++--
>  include/linux/i3c/master.h |  2 ++
>  2 files changed, 70 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/i3c/master.c b/drivers/i3c/master.c
> index 9e6be49bebb2..886637757c26 100644
> --- a/drivers/i3c/master.c
> +++ b/drivers/i3c/master.c
> @@ -1619,8 +1619,23 @@ 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_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;
> @@ -1644,6 +1659,7 @@ 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)
>  {
> @@ -3168,6 +3184,16 @@ int i3c_dev_do_xfers_locked(struct i3c_dev_desc *dev, struct i3c_xfer *xfers,
>  	return master->ops->i3c_xfers(dev, xfers, nxfers, mode);
>  }
>
> +/**
> + * i3c_dev_disable_ibi() - Disable IBIs coming from a specific device
> + * @dev: device on which IBIs should be disabled
> + *
> + * This function disable IBIs coming from a specific device and wait for
> + * all pending IBIs to be processed.
> + *
> + * Context: Must be called with mutex_lock(&dev->desc->ibi_lock) held.
> + * Return: 0 in case of success, a negative error core otherwise.
> + */
>  int i3c_dev_disable_ibi_locked(struct i3c_dev_desc *dev)
>  {
>  	struct i3c_master_controller *master;
> @@ -3189,7 +3215,22 @@ int i3c_dev_disable_ibi_locked(struct i3c_dev_desc *dev)
>
>  	return 0;
>  }
> +EXPORT_SYMBOL_GPL(i3c_dev_disable_ibi_locked);
>
> +/**
> + * i3c_dev_enable_ibi_locked() - Enable IBIs from a specific device (lock held)
> + * @dev: device on which IBIs should be enabled
> + *
> + * This function enable IBIs coming from a specific device and wait for
> + * all pending IBIs to be processed. This should be called on a device
> + * where i3c_device_request_ibi() has succeeded.
> + *
> + * Note that IBIs from this device might be received before this function
> + * returns to its caller.
> + *
> + * Context: Must be called with mutex_lock(&dev->desc->ibi_lock) held.
> + * Return: 0 on success, or a negative error code on failure.
> + */
>  int i3c_dev_enable_ibi_locked(struct i3c_dev_desc *dev)
>  {
>  	struct i3c_master_controller *master = i3c_dev_get_master(dev);
> @@ -3204,7 +3245,20 @@ int i3c_dev_enable_ibi_locked(struct i3c_dev_desc *dev)
>
>  	return ret;
>  }
> +EXPORT_SYMBOL_GPL(i3c_dev_enable_ibi_locked);
>
> +/**
> + * i3c_dev_request_ibi() - Request an IBI
> + * @dev: device for which we should enable IBIs
> + * @req: setup requested for this IBI
> + *
> + * This function is responsible for pre-allocating all resources needed to
> + * process IBIs coming from @dev. When this function returns, the IBI is not
> + * enabled until i3c_device_enable_ibi() is called.
> + *
> + * Context: Must be called with mutex_lock(&dev->desc->ibi_lock) held.
> + * Return: 0 in case of success, a negative error core otherwise.
> + */
>  int i3c_dev_request_ibi_locked(struct i3c_dev_desc *dev,
>  			       const struct i3c_ibi_setup *req)
>  {
> @@ -3243,7 +3297,18 @@ int i3c_dev_request_ibi_locked(struct i3c_dev_desc *dev,
>
>  	return ret;
>  }
> +EXPORT_SYMBOL_GPL(i3c_dev_request_ibi_locked);
>
> +/**
> + * i3c_dev_free_ibi() - Free all resources needed for IBI handling
> + * @dev: device on which you want to release IBI resources
> + *
> + * This function is responsible for de-allocating resources previously
> + * allocated by i3c_device_request_ibi(). It should be called after disabling
> + * IBIs with i3c_device_disable_ibi().
> + *
> + * Context: Must be called with mutex_lock(&dev->desc->ibi_lock) held.
> + */
>  void i3c_dev_free_ibi_locked(struct i3c_dev_desc *dev)
>  {
>  	struct i3c_master_controller *master = i3c_dev_get_master(dev);
> @@ -3274,6 +3339,7 @@ void i3c_dev_free_ibi_locked(struct i3c_dev_desc *dev)
>  	kfree(dev->ibi);
>  	dev->ibi = NULL;
>  }
> +EXPORT_SYMBOL_GPL(i3c_dev_free_ibi_locked);
>
>  static int __init i3c_init(void)
>  {
> diff --git a/include/linux/i3c/master.h b/include/linux/i3c/master.h
> index 592b646f6134..aeccec171e64 100644
> --- a/include/linux/i3c/master.h
> +++ b/include/linux/i3c/master.h
> @@ -613,6 +613,8 @@ 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_reattach_i3c_dev(struct i3c_dev_desc *dev,
> +				u8 old_dyn_addr);

how about other functions?  such as i3c_dev_request_ibi_locked()? All
export API should in header files.

Frank

>  int i3c_master_set_info(struct i3c_master_controller *master,
>  			const struct i3c_device_info *info);
>
> --
> 2.25.1
>