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Message-ID: <aYYflbET_ZE1QPDT@lizhi-Precision-Tower-5810>
Date: Fri, 6 Feb 2026 12:06:29 -0500
From: Frank Li <Frank.li@....com>
To: Aman Kumar Pandey <aman.kumarpandey@....com>
Cc: linux-kernel@...r.kernel.org, linux-i3c@...ts.infradead.org,
alexandre.belloni@...tlin.com, krzk+dt@...nel.org, robh@...nel.org,
conor+dt@...nel.org, devicetree@...r.kernel.org, broonie@...nel.org,
lee@...nel.org, lgirdwood@...il.com, vikash.bansal@....com,
priyanka.jain@....com, shashank.rebbapragada@....com
Subject: Re: [PATCH v5 1/5] i3c: master: Expose the APIs to support I3C hub
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@....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
>
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