[PATCH v9 1/7] i3c: master: Expose the APIs to support I3C hub

[Lakshay Piplani <lakshay.piplani@nxp.com>]

From: Aman Kumar Pandey <aman.kumarpandey@nxp.com>

The following APIs were already declared in i3c_internals.h but were
missing EXPORT_SYMBOL_GPL() in their implementation, making them
inaccessible to modular drivers such as the I3C hub driver:

1) i3c_dev_enable_ibi_locked()
2) i3c_dev_disable_ibi_locked()
3) i3c_dev_request_ibi_locked()
4) i3c_dev_free_ibi_locked()

i3c_master_reattach_i3c_dev() is declared in include/linux/i3c/master.h
and exported via EXPORT_SYMBOL_GPL() to make it accessible to the I3C
hub driver.

Signed-off-by: Aman Kumar Pandey <aman.kumarpandey@nxp.com>
Signed-off-by: Lakshay Piplani <lakshay.piplani@nxp.com>

---
Changes in v9:
 - No change

Changes in v8:
 - No change

Changes in v7:
 - Fix kernel-doc warnings for *_locked() APIs
 - Clarify API exposure in commit message

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 5cd4e5da2233..d11fe6937ba8 100644
--- a/drivers/i3c/master.c
+++ b/drivers/i3c/master.c
@@ -1652,8 +1652,23 @@ 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;
@@ -1677,6 +1692,7 @@ 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)
 {
@@ -3195,6 +3211,16 @@ 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_locked() - 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;
@@ -3216,7 +3242,22 @@ 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);
@@ -3231,7 +3272,20 @@ 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_locked() - 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)
 {
@@ -3270,7 +3324,18 @@ 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_locked() - 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);
@@ -3301,6 +3366,7 @@ 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