i3c: master: Consolidate Hot-Join DAA work in the core

Three master drivers (dw-i3c-master, i3c-master-cdns, svc-i3c-master)
each carry an essentially identical Hot-Join handler: a struct
work_struct embedded in their private state, a work function that just
calls i3c_master_do_daa() on the embedded i3c_master_controller, plus
matching INIT_WORK()/cancel_work_sync() boilerplate in probe/remove (and
shutdown for dw-i3c). The IBI/ISR paths then queue that work onto
master->wq, which already lives in the core.

Move this pattern into the I3C core:

 - Add struct work_struct hj_work to struct i3c_master_controller and
   initialise it in i3c_master_register() with a core-provided handler
   i3c_master_hj_work_fn() that performs i3c_master_do_daa().
 - Cancel the work in i3c_master_unregister() so all controllers get
   correct teardown ordering against the workqueue for free.
 - Export i3c_master_queue_hotjoin() as the single entry point drivers
   call from their Hot-Join IBI handler.

Convert the three existing users to the new API: drop their private
hj_work fields, work functions, INIT_WORK() and cancel_work_sync()
calls, and replace the queue_work(master->wq, &drv->hj_work) call sites
with i3c_master_queue_hotjoin(&drv->base). The dw-i3c shutdown path
still needs to flush pending Hot-Join work before tearing down the
hardware, so it is updated to cancel master->base.hj_work directly.

No functional change intended: the work is still queued on the same
master->wq, runs the same i3c_master_do_daa(), and is cancelled at
controller teardown.  Future Hot-Join improvements now only need to
be made in one place.

Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
Reviewed-by: Frank Li <Frank.Li@nxp.com>
Link: https://patch.msgid.link/20260608054312.10604-4-adrian.hunter@intel.com
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>

1 files changed, 4 insertions, 0 deletions

diff --git a/include/linux/i3c/master.h b/include/linux/i3c/master.h
index e6112e5f6608..eb5c51608bd7 100644
--- a/include/linux/i3c/master.h
+++ b/include/linux/i3c/master.h
@@ -520,6 +520,8 @@ struct i3c_master_controller_ops {
  *	in a thread context. Typical examples are Hot Join processing which
  *	requires taking the bus lock in maintenance, which in turn, can only
  *	be done from a sleep-able context
+ * @hj_work: work item used to run DAA after a Hot-Join event is detected.
+ *           Queued to @wq by i3c_master_queue_hotjoin()
  * @dev_nack_retry_count: retry count when slave device nack
  *
  * A &struct i3c_master_controller has to be registered to the I3C subsystem
@@ -543,6 +545,7 @@ struct i3c_master_controller {
 	} boardinfo;
 	struct i3c_bus bus;
 	struct workqueue_struct *wq;
+	struct work_struct hj_work;
 	unsigned int dev_nack_retry_count;
 };
 
@@ -623,6 +626,7 @@ int i3c_master_register(struct i3c_master_controller *master,
 void i3c_master_unregister(struct i3c_master_controller *master);
 int i3c_master_enable_hotjoin(struct i3c_master_controller *master);
 int i3c_master_disable_hotjoin(struct i3c_master_controller *master);
+void i3c_master_queue_hotjoin(struct i3c_master_controller *master);
 
 /**
  * i3c_dev_get_master_data() - get master private data attached to an I3C