mei: bus: add me client device list infrastructure

Instead of holding the list of host clients (me_cl)
we want to keep the list me client devices (mei_cl_device)
This way we can create host to me client connection only when needed.
Add list head to mei_cl_device and cl_bus_lock
Add bus_added flag to the me client (mei_me_client) to track if
the appropriate mei_cl_device was already created and is_added
flag to mei_cl_device to track if it was already added to the device
list across the bus rescans

Signed-off-by: Tomas Winkler <tomas.winkler@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/misc/mei/bus.c

@@ -657,6 +657,7 @@ struct mei_cl_device *mei_cl_add_device(struct mei_device *bus,
 	cldev->dev.bus = &mei_cl_bus_type;
 	cldev->dev.type = &mei_cl_device_type;
 	cldev->bus      = mei_dev_bus_get(bus);
+	INIT_LIST_HEAD(&cldev->bus_list);
 
 	strlcpy(cldev->name, name, sizeof(cldev->name));
 

drivers/misc/mei/init.c

@@ -390,6 +390,7 @@ void mei_device_init(struct mei_device *dev,
 	INIT_LIST_HEAD(&dev->me_clients);
 	mutex_init(&dev->device_lock);
 	init_rwsem(&dev->me_clients_rwsem);
+	mutex_init(&dev->cl_bus_lock);
 	init_waitqueue_head(&dev->wait_hw_ready);
 	init_waitqueue_head(&dev->wait_pg);
 	init_waitqueue_head(&dev->wait_hbm_start);

drivers/misc/mei/mei_dev.h

@@ -178,7 +178,7 @@ struct mei_fw_status {
  * @client_id: me client id
  * @mei_flow_ctrl_creds: flow control credits
  * @connect_count: number connections to this client
- * @reserved: reserved
+ * @bus_added: added to bus
  */
 struct mei_me_client {
 	struct list_head list;
@@ -187,7 +187,7 @@ struct mei_me_client {
 	u8 client_id;
 	u8 mei_flow_ctrl_creds;
 	u8 connect_count;
-	u8 reserved;
+	u8 bus_added;
 };
 
 
@@ -447,6 +447,7 @@ const char *mei_pg_state_str(enum mei_pg_state state);
  * @reset_work  : work item for the device reset
  *
  * @device_list : mei client bus list
+ * @cl_bus_lock : client bus list lock
  *
  * @dbgfs_dir   : debugfs mei root directory
  *
@@ -543,6 +544,7 @@ struct mei_device {
 
 	/* List of bus devices */
 	struct list_head device_list;
+	struct mutex cl_bus_lock;
 
 #if IS_ENABLED(CONFIG_DEBUG_FS)
 	struct dentry *dbgfs_dir;

include/linux/mei_cl_bus.h

@@ -18,6 +18,7 @@ typedef void (*mei_cl_event_cb_t)(struct mei_cl_device *device,
  * Drivers for MEI devices will get an mei_cl_device pointer
  * when being probed and shall use it for doing ME bus I/O.
  *
+ * @bus_list: device on the bus list
  * @bus: parent mei device
  * @dev: linux driver model device pointer
  * @me_cl: me client
@@ -28,9 +29,11 @@ typedef void (*mei_cl_event_cb_t)(struct mei_cl_device *device,
  *	events (e.g. Rx buffer pending) notifications.
  * @event_context: event callback run context
  * @events: Events bitmask sent to the driver.
+ * @is_added: device is already scanned
  * @priv_data: client private data
  */
 struct mei_cl_device {
+	struct list_head bus_list;
 	struct mei_device *bus;
 	struct device dev;
 
@@ -42,6 +45,7 @@ struct mei_cl_device {
 	mei_cl_event_cb_t event_cb;
 	void *event_context;
 	unsigned long events;
+	unsigned int is_added:1;
 
 	void *priv_data;
 };