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

Lakshay Piplani
2026-03-10T06:57:37Z

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

--
2.25.1