+/**
+ * struct st_data_s - ST core internal structure
+ * @st_state: different states of ST like initializing, registration
+ * in progress, this is mainly used to return relevant err codes
+ * when protocol drivers are registering. It is also used to track
+ * the recv function, as in during fw download only HCI events
+ * can occur , where as during other times other events CH8, CH9
+ * can occur.
+ * @tty: tty provided by the TTY core for line disciplines.
+ * @ldisc_ops: the procedures that this line discipline registers with TTY.
+ * @tx_skb: If for some reason the tty's write returns lesser bytes written
+ * then to maintain the rest of data to be written on next instance.
+ * This needs to be protected, hence the lock inside wakeup func.
+ * @tx_state: if the data is being written onto the TTY and protocol driver
+ * wants to send more, queue up data and mark that there is
+ * more data to send.
+ * @list: the list of protocols registered, only MAX can exist, one protocol
+ * can register only once.
+ * @rx_state: states to be maintained inside st's tty receive
+ * @rx_count: count to be maintained inside st's tty receieve
+ * @rx_skb: the skb where all data for a protocol gets accumulated,
+ * since tty might not call receive when a complete event packet
+ * is received, the states, count and the skb needs to be maintained.
+ * @txq: the list of skbs which needs to be sent onto the TTY.
+ * @tx_waitq: if the chip is not in AWAKE state, the skbs needs to be queued
+ * up in here, PM(WAKEUP_IND) data needs to be sent and then the skbs
+ * from waitq can be moved onto the txq.
+ * Needs locking too.
+ * @lock: the lock to protect skbs, queues, and ST states.
+ * @protos_registered: count of the protocols registered, also when 0 the
+ * chip enable gpio can be toggled, and when it changes to 1 the fw
+ * needs to be downloaded to initialize chip side ST.
+ * @ll_state: the various PM states the chip can be, the states are notified
+ * to us, when the chip sends relevant PM packets(SLEEP_IND, WAKE_IND).
+ * @kim_data: reference to the parent encapsulating structure.
+ *