Adding upstream version 5.10.209.upstream/5.10.209

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 929 insertions, 0 deletions

diff --git a/drivers/misc/ti-st/st_core.c b/drivers/misc/ti-st/st_core.c
new file mode 100644
index 000000000..ca115f344
--- /dev/null
+++ b/drivers/misc/ti-st/st_core.c
@@ -0,0 +1,929 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ *  Shared Transport Line discipline driver Core
+ *	This hooks up ST KIM driver and ST LL driver
+ *  Copyright (C) 2009-2010 Texas Instruments
+ *  Author: Pavan Savoy <pavan_savoy@ti.com>
+ */
+
+#define pr_fmt(fmt)	"(stc): " fmt
+#include <linux/module.h>
+#include <linux/kernel.h>
+#include <linux/tty.h>
+
+#include <linux/seq_file.h>
+#include <linux/skbuff.h>
+
+#include <linux/ti_wilink_st.h>
+#include <linux/netdevice.h>
+
+extern void st_kim_recv(void *, const unsigned char *, long);
+void st_int_recv(void *, const unsigned char *, long);
+/*
+ * function pointer pointing to either,
+ * st_kim_recv during registration to receive fw download responses
+ * st_int_recv after registration to receive proto stack responses
+ */
+static void (*st_recv) (void *, const unsigned char *, long);
+
+/********************************************************************/
+static void add_channel_to_table(struct st_data_s *st_gdata,
+		struct st_proto_s *new_proto)
+{
+	pr_info("%s: id %d\n", __func__, new_proto->chnl_id);
+	/* list now has the channel id as index itself */
+	st_gdata->list[new_proto->chnl_id] = new_proto;
+	st_gdata->is_registered[new_proto->chnl_id] = true;
+}
+
+static void remove_channel_from_table(struct st_data_s *st_gdata,
+		struct st_proto_s *proto)
+{
+	pr_info("%s: id %d\n", __func__, proto->chnl_id);
+/*	st_gdata->list[proto->chnl_id] = NULL; */
+	st_gdata->is_registered[proto->chnl_id] = false;
+}
+
+/*
+ * called from KIM during firmware download.
+ *
+ * This is a wrapper function to tty->ops->write_room.
+ * It returns number of free space available in
+ * uart tx buffer.
+ */
+int st_get_uart_wr_room(struct st_data_s *st_gdata)
+{
+	struct tty_struct *tty;
+	if (unlikely(st_gdata == NULL || st_gdata->tty == NULL)) {
+		pr_err("tty unavailable to perform write");
+		return -1;
+	}
+	tty = st_gdata->tty;
+	return tty->ops->write_room(tty);
+}
+
+/*
+ * can be called in from
+ * -- KIM (during fw download)
+ * -- ST Core (during st_write)
+ *
+ *  This is the internal write function - a wrapper
+ *  to tty->ops->write
+ */
+int st_int_write(struct st_data_s *st_gdata,
+	const unsigned char *data, int count)
+{
+	struct tty_struct *tty;
+	if (unlikely(st_gdata == NULL || st_gdata->tty == NULL)) {
+		pr_err("tty unavailable to perform write");
+		return -EINVAL;
+	}
+	tty = st_gdata->tty;
+#ifdef VERBOSE
+	print_hex_dump(KERN_DEBUG, "<out<", DUMP_PREFIX_NONE,
+		16, 1, data, count, 0);
+#endif
+	return tty->ops->write(tty, data, count);
+
+}
+
+/*
+ * push the skb received to relevant
+ * protocol stacks
+ */
+static void st_send_frame(unsigned char chnl_id, struct st_data_s *st_gdata)
+{
+	pr_debug(" %s(prot:%d) ", __func__, chnl_id);
+
+	if (unlikely
+	    (st_gdata == NULL || st_gdata->rx_skb == NULL
+	     || st_gdata->is_registered[chnl_id] == false)) {
+		pr_err("chnl_id %d not registered, no data to send?",
+			   chnl_id);
+		kfree_skb(st_gdata->rx_skb);
+		return;
+	}
+	/*
+	 * this cannot fail
+	 * this shouldn't take long
+	 * - should be just skb_queue_tail for the
+	 *   protocol stack driver
+	 */
+	if (likely(st_gdata->list[chnl_id]->recv != NULL)) {
+		if (unlikely
+			(st_gdata->list[chnl_id]->recv
+			(st_gdata->list[chnl_id]->priv_data, st_gdata->rx_skb)
+			     != 0)) {
+			pr_err(" proto stack %d's ->recv failed", chnl_id);
+			kfree_skb(st_gdata->rx_skb);
+			return;
+		}
+	} else {
+		pr_err(" proto stack %d's ->recv null", chnl_id);
+		kfree_skb(st_gdata->rx_skb);
+	}
+	return;
+}
+
+/*
+ * st_reg_complete - to call registration complete callbacks
+ * of all protocol stack drivers
+ * This function is being called with spin lock held, protocol drivers are
+ * only expected to complete their waits and do nothing more than that.
+ */
+static void st_reg_complete(struct st_data_s *st_gdata, int err)
+{
+	unsigned char i = 0;
+	pr_info(" %s ", __func__);
+	for (i = 0; i < ST_MAX_CHANNELS; i++) {
+		if (likely(st_gdata != NULL &&
+			st_gdata->is_registered[i] == true &&
+				st_gdata->list[i]->reg_complete_cb != NULL)) {
+			st_gdata->list[i]->reg_complete_cb
+				(st_gdata->list[i]->priv_data, err);
+			pr_info("protocol %d's cb sent %d\n", i, err);
+			if (err) { /* cleanup registered protocol */
+				st_gdata->is_registered[i] = false;
+				if (st_gdata->protos_registered)
+					st_gdata->protos_registered--;
+			}
+		}
+	}
+}
+
+static inline int st_check_data_len(struct st_data_s *st_gdata,
+	unsigned char chnl_id, int len)
+{
+	int room = skb_tailroom(st_gdata->rx_skb);
+
+	pr_debug("len %d room %d", len, room);
+
+	if (!len) {
+		/*
+		 * Received packet has only packet header and
+		 * has zero length payload. So, ask ST CORE to
+		 * forward the packet to protocol driver (BT/FM/GPS)
+		 */
+		st_send_frame(chnl_id, st_gdata);
+
+	} else if (len > room) {
+		/*
+		 * Received packet's payload length is larger.
+		 * We can't accommodate it in created skb.
+		 */
+		pr_err("Data length is too large len %d room %d", len,
+			   room);
+		kfree_skb(st_gdata->rx_skb);
+	} else {
+		/*
+		 * Packet header has non-zero payload length and
+		 * we have enough space in created skb. Lets read
+		 * payload data */
+		st_gdata->rx_state = ST_W4_DATA;
+		st_gdata->rx_count = len;
+		return len;
+	}
+
+	/* Change ST state to continue to process next packet */
+	st_gdata->rx_state = ST_W4_PACKET_TYPE;
+	st_gdata->rx_skb = NULL;
+	st_gdata->rx_count = 0;
+	st_gdata->rx_chnl = 0;
+
+	return 0;
+}
+
+/*
+ * st_wakeup_ack - internal function for action when wake-up ack
+ *	received
+ */
+static inline void st_wakeup_ack(struct st_data_s *st_gdata,
+	unsigned char cmd)
+{
+	struct sk_buff *waiting_skb;
+	unsigned long flags = 0;
+
+	spin_lock_irqsave(&st_gdata->lock, flags);
+	/*
+	 * de-Q from waitQ and Q in txQ now that the
+	 * chip is awake
+	 */
+	while ((waiting_skb = skb_dequeue(&st_gdata->tx_waitq)))
+		skb_queue_tail(&st_gdata->txq, waiting_skb);
+
+	/* state forwarded to ST LL */
+	st_ll_sleep_state(st_gdata, (unsigned long)cmd);
+	spin_unlock_irqrestore(&st_gdata->lock, flags);
+
+	/* wake up to send the recently copied skbs from waitQ */
+	st_tx_wakeup(st_gdata);
+}
+
+/*
+ * st_int_recv - ST's internal receive function.
+ *	Decodes received RAW data and forwards to corresponding
+ *	client drivers (Bluetooth,FM,GPS..etc).
+ *	This can receive various types of packets,
+ *	HCI-Events, ACL, SCO, 4 types of HCI-LL PM packets
+ *	CH-8 packets from FM, CH-9 packets from GPS cores.
+ */
+void st_int_recv(void *disc_data,
+	const unsigned char *data, long count)
+{
+	char *ptr;
+	struct st_proto_s *proto;
+	unsigned short payload_len = 0;
+	int len = 0;
+	unsigned char type = 0;
+	unsigned char *plen;
+	struct st_data_s *st_gdata = (struct st_data_s *)disc_data;
+	unsigned long flags;
+
+	ptr = (char *)data;
+	/* tty_receive sent null ? */
+	if (unlikely(ptr == NULL) || (st_gdata == NULL)) {
+		pr_err(" received null from TTY ");
+		return;
+	}
+
+	pr_debug("count %ld rx_state %ld"
+		   "rx_count %ld", count, st_gdata->rx_state,
+		   st_gdata->rx_count);
+
+	spin_lock_irqsave(&st_gdata->lock, flags);
+	/* Decode received bytes here */
+	while (count) {
+		if (st_gdata->rx_count) {
+			len = min_t(unsigned int, st_gdata->rx_count, count);
+			skb_put_data(st_gdata->rx_skb, ptr, len);
+			st_gdata->rx_count -= len;
+			count -= len;
+			ptr += len;
+
+			if (st_gdata->rx_count)
+				continue;
+
+			/* Check ST RX state machine , where are we? */
+			switch (st_gdata->rx_state) {
+			/* Waiting for complete packet ? */
+			case ST_W4_DATA:
+				pr_debug("Complete pkt received");
+				/*
+				 * Ask ST CORE to forward
+				 * the packet to protocol driver
+				 */
+				st_send_frame(st_gdata->rx_chnl, st_gdata);
+
+				st_gdata->rx_state = ST_W4_PACKET_TYPE;
+				st_gdata->rx_skb = NULL;
+				continue;
+			/* parse the header to know details */
+			case ST_W4_HEADER:
+				proto = st_gdata->list[st_gdata->rx_chnl];
+				plen =
+				&st_gdata->rx_skb->data
+				[proto->offset_len_in_hdr];
+				pr_debug("plen pointing to %x\n", *plen);
+				if (proto->len_size == 1) /* 1 byte len field */
+					payload_len = *(unsigned char *)plen;
+				else if (proto->len_size == 2)
+					payload_len =
+					__le16_to_cpu(*(unsigned short *)plen);
+				else
+					pr_info("%s: invalid length "
+					"for id %d\n",
+					__func__, proto->chnl_id);
+				st_check_data_len(st_gdata, proto->chnl_id,
+						payload_len);
+				pr_debug("off %d, pay len %d\n",
+					proto->offset_len_in_hdr, payload_len);
+				continue;
+			}	/* end of switch rx_state */
+		}
+
+		/* end of if rx_count */
+
+		/*
+		 * Check first byte of packet and identify module
+		 * owner (BT/FM/GPS)
+		 */
+		switch (*ptr) {
+		case LL_SLEEP_IND:
+		case LL_SLEEP_ACK:
+		case LL_WAKE_UP_IND:
+			pr_debug("PM packet");
+			/*
+			 * this takes appropriate action based on
+			 * sleep state received --
+			 */
+			st_ll_sleep_state(st_gdata, *ptr);
+			/*
+			 * if WAKEUP_IND collides copy from waitq to txq
+			 * and assume chip awake
+			 */
+			spin_unlock_irqrestore(&st_gdata->lock, flags);
+			if (st_ll_getstate(st_gdata) == ST_LL_AWAKE)
+				st_wakeup_ack(st_gdata, LL_WAKE_UP_ACK);
+			spin_lock_irqsave(&st_gdata->lock, flags);
+
+			ptr++;
+			count--;
+			continue;
+		case LL_WAKE_UP_ACK:
+			pr_debug("PM packet");
+
+			spin_unlock_irqrestore(&st_gdata->lock, flags);
+			/* wake up ack received */
+			st_wakeup_ack(st_gdata, *ptr);
+			spin_lock_irqsave(&st_gdata->lock, flags);
+
+			ptr++;
+			count--;
+			continue;
+			/* Unknow packet? */
+		default:
+			type = *ptr;
+
+			/*
+			 * Default case means non-HCILL packets,
+			 * possibilities are packets for:
+			 * (a) valid protocol -  Supported Protocols within
+			 *     the ST_MAX_CHANNELS.
+			 * (b) registered protocol - Checked by
+			 *     "st_gdata->list[type] == NULL)" are supported
+			 *     protocols only.
+			 *  Rules out any invalid protocol and
+			 *  unregistered protocols with channel ID < 16.
+			 */
+
+			if ((type >= ST_MAX_CHANNELS) ||
+					(st_gdata->list[type] == NULL)) {
+				pr_err("chip/interface misbehavior: "
+						"dropping frame starting "
+						"with 0x%02x\n", type);
+				goto done;
+			}
+
+			st_gdata->rx_skb = alloc_skb(
+					st_gdata->list[type]->max_frame_size,
+					GFP_ATOMIC);
+			if (st_gdata->rx_skb == NULL) {
+				pr_err("out of memory: dropping\n");
+				goto done;
+			}
+
+			skb_reserve(st_gdata->rx_skb,
+					st_gdata->list[type]->reserve);
+			/* next 2 required for BT only */
+			st_gdata->rx_skb->cb[0] = type; /*pkt_type*/
+			st_gdata->rx_skb->cb[1] = 0; /*incoming*/
+			st_gdata->rx_chnl = *ptr;
+			st_gdata->rx_state = ST_W4_HEADER;
+			st_gdata->rx_count = st_gdata->list[type]->hdr_len;
+			pr_debug("rx_count %ld\n", st_gdata->rx_count);
+		};
+		ptr++;
+		count--;
+	}
+done:
+	spin_unlock_irqrestore(&st_gdata->lock, flags);
+	pr_debug("done %s", __func__);
+	return;
+}
+
+/*
+ * st_int_dequeue - internal de-Q function.
+ *	If the previous data set was not written
+ *	completely, return that skb which has the pending data.
+ *	In normal cases, return top of txq.
+ */
+static struct sk_buff *st_int_dequeue(struct st_data_s *st_gdata)
+{
+	struct sk_buff *returning_skb;
+
+	pr_debug("%s", __func__);
+	if (st_gdata->tx_skb != NULL) {
+		returning_skb = st_gdata->tx_skb;
+		st_gdata->tx_skb = NULL;
+		return returning_skb;
+	}
+	return skb_dequeue(&st_gdata->txq);
+}
+
+/*
+ * st_int_enqueue - internal Q-ing function.
+ *	Will either Q the skb to txq or the tx_waitq
+ *	depending on the ST LL state.
+ *	If the chip is asleep, then Q it onto waitq and
+ *	wakeup the chip.
+ *	txq and waitq needs protection since the other contexts
+ *	may be sending data, waking up chip.
+ */
+static void st_int_enqueue(struct st_data_s *st_gdata, struct sk_buff *skb)
+{
+	unsigned long flags = 0;
+
+	pr_debug("%s", __func__);
+	spin_lock_irqsave(&st_gdata->lock, flags);
+
+	switch (st_ll_getstate(st_gdata)) {
+	case ST_LL_AWAKE:
+		pr_debug("ST LL is AWAKE, sending normally");
+		skb_queue_tail(&st_gdata->txq, skb);
+		break;
+	case ST_LL_ASLEEP_TO_AWAKE:
+		skb_queue_tail(&st_gdata->tx_waitq, skb);
+		break;
+	case ST_LL_AWAKE_TO_ASLEEP:
+		pr_err("ST LL is illegal state(%ld),"
+			   "purging received skb.", st_ll_getstate(st_gdata));
+		dev_kfree_skb_irq(skb);
+		break;
+	case ST_LL_ASLEEP:
+		skb_queue_tail(&st_gdata->tx_waitq, skb);
+		st_ll_wakeup(st_gdata);
+		break;
+	default:
+		pr_err("ST LL is illegal state(%ld),"
+			   "purging received skb.", st_ll_getstate(st_gdata));
+		dev_kfree_skb_irq(skb);
+		break;
+	}
+
+	spin_unlock_irqrestore(&st_gdata->lock, flags);
+	pr_debug("done %s", __func__);
+	return;
+}
+
+/*
+ * internal wakeup function
+ * called from either
+ * - TTY layer when write's finished
+ * - st_write (in context of the protocol stack)
+ */
+static void work_fn_write_wakeup(struct work_struct *work)
+{
+	struct st_data_s *st_gdata = container_of(work, struct st_data_s,
+			work_write_wakeup);
+
+	st_tx_wakeup((void *)st_gdata);
+}
+void st_tx_wakeup(struct st_data_s *st_data)
+{
+	struct sk_buff *skb;
+	unsigned long flags;	/* for irq save flags */
+	pr_debug("%s", __func__);
+	/* check for sending & set flag sending here */
+	if (test_and_set_bit(ST_TX_SENDING, &st_data->tx_state)) {
+		pr_debug("ST already sending");
+		/* keep sending */
+		set_bit(ST_TX_WAKEUP, &st_data->tx_state);
+		return;
+		/* TX_WAKEUP will be checked in another
+		 * context
+		 */
+	}
+	do {			/* come back if st_tx_wakeup is set */
+		/* woke-up to write */
+		clear_bit(ST_TX_WAKEUP, &st_data->tx_state);
+		while ((skb = st_int_dequeue(st_data))) {
+			int len;
+			spin_lock_irqsave(&st_data->lock, flags);
+			/* enable wake-up from TTY */
+			set_bit(TTY_DO_WRITE_WAKEUP, &st_data->tty->flags);
+			len = st_int_write(st_data, skb->data, skb->len);
+			skb_pull(skb, len);
+			/* if skb->len = len as expected, skb->len=0 */
+			if (skb->len) {
+				/* would be the next skb to be sent */
+				st_data->tx_skb = skb;
+				spin_unlock_irqrestore(&st_data->lock, flags);
+				break;
+			}
+			dev_kfree_skb_irq(skb);
+			spin_unlock_irqrestore(&st_data->lock, flags);
+		}
+		/* if wake-up is set in another context- restart sending */
+	} while (test_bit(ST_TX_WAKEUP, &st_data->tx_state));
+
+	/* clear flag sending */
+	clear_bit(ST_TX_SENDING, &st_data->tx_state);
+}
+
+/********************************************************************/
+/* functions called from ST KIM
+*/
+void kim_st_list_protocols(struct st_data_s *st_gdata, void *buf)
+{
+	seq_printf(buf, "[%d]\nBT=%c\nFM=%c\nGPS=%c\n",
+			st_gdata->protos_registered,
+			st_gdata->is_registered[0x04] == true ? 'R' : 'U',
+			st_gdata->is_registered[0x08] == true ? 'R' : 'U',
+			st_gdata->is_registered[0x09] == true ? 'R' : 'U');
+}
+
+/********************************************************************/
+/*
+ * functions called from protocol stack drivers
+ * to be EXPORT-ed
+ */
+long st_register(struct st_proto_s *new_proto)
+{
+	struct st_data_s	*st_gdata;
+	long err = 0;
+	unsigned long flags = 0;
+
+	st_kim_ref(&st_gdata, 0);
+	if (st_gdata == NULL || new_proto == NULL || new_proto->recv == NULL
+	    || new_proto->reg_complete_cb == NULL) {
+		pr_err("gdata/new_proto/recv or reg_complete_cb not ready");
+		return -EINVAL;
+	}
+
+	if (new_proto->chnl_id >= ST_MAX_CHANNELS) {
+		pr_err("chnl_id %d not supported", new_proto->chnl_id);
+		return -EPROTONOSUPPORT;
+	}
+
+	if (st_gdata->is_registered[new_proto->chnl_id] == true) {
+		pr_err("chnl_id %d already registered", new_proto->chnl_id);
+		return -EALREADY;
+	}
+
+	/* can be from process context only */
+	spin_lock_irqsave(&st_gdata->lock, flags);
+
+	if (test_bit(ST_REG_IN_PROGRESS, &st_gdata->st_state)) {
+		pr_info(" ST_REG_IN_PROGRESS:%d ", new_proto->chnl_id);
+		/* fw download in progress */
+
+		add_channel_to_table(st_gdata, new_proto);
+		st_gdata->protos_registered++;
+		new_proto->write = st_write;
+
+		set_bit(ST_REG_PENDING, &st_gdata->st_state);
+		spin_unlock_irqrestore(&st_gdata->lock, flags);
+		return -EINPROGRESS;
+	} else if (st_gdata->protos_registered == ST_EMPTY) {
+		pr_info(" chnl_id list empty :%d ", new_proto->chnl_id);
+		set_bit(ST_REG_IN_PROGRESS, &st_gdata->st_state);
+		st_recv = st_kim_recv;
+
+		/* enable the ST LL - to set default chip state */
+		st_ll_enable(st_gdata);
+
+		/* release lock previously held - re-locked below */
+		spin_unlock_irqrestore(&st_gdata->lock, flags);
+
+		/*
+		 * this may take a while to complete
+		 * since it involves BT fw download
+		 */
+		err = st_kim_start(st_gdata->kim_data);
+		if (err != 0) {
+			clear_bit(ST_REG_IN_PROGRESS, &st_gdata->st_state);
+			if ((st_gdata->protos_registered != ST_EMPTY) &&
+			    (test_bit(ST_REG_PENDING, &st_gdata->st_state))) {
+				pr_err(" KIM failure complete callback ");
+				spin_lock_irqsave(&st_gdata->lock, flags);
+				st_reg_complete(st_gdata, err);
+				spin_unlock_irqrestore(&st_gdata->lock, flags);
+				clear_bit(ST_REG_PENDING, &st_gdata->st_state);
+			}
+			return -EINVAL;
+		}
+
+		spin_lock_irqsave(&st_gdata->lock, flags);
+
+		clear_bit(ST_REG_IN_PROGRESS, &st_gdata->st_state);
+		st_recv = st_int_recv;
+
+		/*
+		 * this is where all pending registration
+		 * are signalled to be complete by calling callback functions
+		 */
+		if ((st_gdata->protos_registered != ST_EMPTY) &&
+		    (test_bit(ST_REG_PENDING, &st_gdata->st_state))) {
+			pr_debug(" call reg complete callback ");
+			st_reg_complete(st_gdata, 0);
+		}
+		clear_bit(ST_REG_PENDING, &st_gdata->st_state);
+
+		/*
+		 * check for already registered once more,
+		 * since the above check is old
+		 */
+		if (st_gdata->is_registered[new_proto->chnl_id] == true) {
+			pr_err(" proto %d already registered ",
+				   new_proto->chnl_id);
+			spin_unlock_irqrestore(&st_gdata->lock, flags);
+			return -EALREADY;
+		}
+
+		add_channel_to_table(st_gdata, new_proto);
+		st_gdata->protos_registered++;
+		new_proto->write = st_write;
+		spin_unlock_irqrestore(&st_gdata->lock, flags);
+		return err;
+	}
+	/* if fw is already downloaded & new stack registers protocol */
+	else {
+		add_channel_to_table(st_gdata, new_proto);
+		st_gdata->protos_registered++;
+		new_proto->write = st_write;
+
+		/* lock already held before entering else */
+		spin_unlock_irqrestore(&st_gdata->lock, flags);
+		return err;
+	}
+}
+EXPORT_SYMBOL_GPL(st_register);
+
+/*
+ * to unregister a protocol -
+ * to be called from protocol stack driver
+ */
+long st_unregister(struct st_proto_s *proto)
+{
+	long err = 0;
+	unsigned long flags = 0;
+	struct st_data_s	*st_gdata;
+
+	pr_debug("%s: %d ", __func__, proto->chnl_id);
+
+	st_kim_ref(&st_gdata, 0);
+	if (!st_gdata || proto->chnl_id >= ST_MAX_CHANNELS) {
+		pr_err(" chnl_id %d not supported", proto->chnl_id);
+		return -EPROTONOSUPPORT;
+	}
+
+	spin_lock_irqsave(&st_gdata->lock, flags);
+
+	if (st_gdata->is_registered[proto->chnl_id] == false) {
+		pr_err(" chnl_id %d not registered", proto->chnl_id);
+		spin_unlock_irqrestore(&st_gdata->lock, flags);
+		return -EPROTONOSUPPORT;
+	}
+
+	if (st_gdata->protos_registered)
+		st_gdata->protos_registered--;
+
+	remove_channel_from_table(st_gdata, proto);
+	spin_unlock_irqrestore(&st_gdata->lock, flags);
+
+	if ((st_gdata->protos_registered == ST_EMPTY) &&
+	    (!test_bit(ST_REG_PENDING, &st_gdata->st_state))) {
+		pr_info(" all chnl_ids unregistered ");
+
+		/* stop traffic on tty */
+		if (st_gdata->tty) {
+			tty_ldisc_flush(st_gdata->tty);
+			stop_tty(st_gdata->tty);
+		}
+
+		/* all chnl_ids now unregistered */
+		st_kim_stop(st_gdata->kim_data);
+		/* disable ST LL */
+		st_ll_disable(st_gdata);
+	}
+	return err;
+}
+
+/*
+ * called in protocol stack drivers
+ * via the write function pointer
+ */
+long st_write(struct sk_buff *skb)
+{
+	struct st_data_s *st_gdata;
+	long len;
+
+	st_kim_ref(&st_gdata, 0);
+	if (unlikely(skb == NULL || st_gdata == NULL
+		|| st_gdata->tty == NULL)) {
+		pr_err("data/tty unavailable to perform write");
+		return -EINVAL;
+	}
+
+	pr_debug("%d to be written", skb->len);
+	len = skb->len;
+
+	/* st_ll to decide where to enqueue the skb */
+	st_int_enqueue(st_gdata, skb);
+	/* wake up */
+	st_tx_wakeup(st_gdata);
+
+	/* return number of bytes written */
+	return len;
+}
+
+/* for protocols making use of shared transport */
+EXPORT_SYMBOL_GPL(st_unregister);
+
+/********************************************************************/
+/*
+ * functions called from TTY layer
+ */
+static int st_tty_open(struct tty_struct *tty)
+{
+	struct st_data_s *st_gdata;
+	pr_info("%s ", __func__);
+
+	st_kim_ref(&st_gdata, 0);
+	st_gdata->tty = tty;
+	tty->disc_data = st_gdata;
+
+	/* don't do an wakeup for now */
+	clear_bit(TTY_DO_WRITE_WAKEUP, &tty->flags);
+
+	/* mem already allocated
+	 */
+	tty->receive_room = 65536;
+	/* Flush any pending characters in the driver and discipline. */
+	tty_ldisc_flush(tty);
+	tty_driver_flush_buffer(tty);
+	/*
+	 * signal to UIM via KIM that -
+	 * installation of N_TI_WL ldisc is complete
+	 */
+	st_kim_complete(st_gdata->kim_data);
+	pr_debug("done %s", __func__);
+
+	return 0;
+}
+
+static void st_tty_close(struct tty_struct *tty)
+{
+	unsigned char i;
+	unsigned long flags;
+	struct	st_data_s *st_gdata = tty->disc_data;
+
+	pr_info("%s ", __func__);
+
+	/*
+	 * TODO:
+	 * if a protocol has been registered & line discipline
+	 * un-installed for some reason - what should be done ?
+	 */
+	spin_lock_irqsave(&st_gdata->lock, flags);
+	for (i = ST_BT; i < ST_MAX_CHANNELS; i++) {
+		if (st_gdata->is_registered[i] == true)
+			pr_err("%d not un-registered", i);
+		st_gdata->list[i] = NULL;
+		st_gdata->is_registered[i] = false;
+	}
+	st_gdata->protos_registered = 0;
+	spin_unlock_irqrestore(&st_gdata->lock, flags);
+	/*
+	 * signal to UIM via KIM that -
+	 * N_TI_WL ldisc is un-installed
+	 */
+	st_kim_complete(st_gdata->kim_data);
+	st_gdata->tty = NULL;
+	/* Flush any pending characters in the driver and discipline. */
+	tty_ldisc_flush(tty);
+	tty_driver_flush_buffer(tty);
+
+	spin_lock_irqsave(&st_gdata->lock, flags);
+	/* empty out txq and tx_waitq */
+	skb_queue_purge(&st_gdata->txq);
+	skb_queue_purge(&st_gdata->tx_waitq);
+	/* reset the TTY Rx states of ST */
+	st_gdata->rx_count = 0;
+	st_gdata->rx_state = ST_W4_PACKET_TYPE;
+	kfree_skb(st_gdata->rx_skb);
+	st_gdata->rx_skb = NULL;
+	spin_unlock_irqrestore(&st_gdata->lock, flags);
+
+	pr_debug("%s: done ", __func__);
+}
+
+static void st_tty_receive(struct tty_struct *tty, const unsigned char *data,
+			   char *tty_flags, int count)
+{
+#ifdef VERBOSE
+	print_hex_dump(KERN_DEBUG, ">in>", DUMP_PREFIX_NONE,
+		16, 1, data, count, 0);
+#endif
+
+	/*
+	 * if fw download is in progress then route incoming data
+	 * to KIM for validation
+	 */
+	st_recv(tty->disc_data, data, count);
+	pr_debug("done %s", __func__);
+}
+
+/*
+ * wake-up function called in from the TTY layer
+ * inside the internal wakeup function will be called
+ */
+static void st_tty_wakeup(struct tty_struct *tty)
+{
+	struct	st_data_s *st_gdata = tty->disc_data;
+	pr_debug("%s ", __func__);
+	/* don't do an wakeup for now */
+	clear_bit(TTY_DO_WRITE_WAKEUP, &tty->flags);
+
+	/*
+	 * schedule the internal wakeup instead of calling directly to
+	 * avoid lockup (port->lock needed in tty->ops->write is
+	 * already taken here
+	 */
+	schedule_work(&st_gdata->work_write_wakeup);
+}
+
+static void st_tty_flush_buffer(struct tty_struct *tty)
+{
+	struct	st_data_s *st_gdata = tty->disc_data;
+	pr_debug("%s ", __func__);
+
+	kfree_skb(st_gdata->tx_skb);
+	st_gdata->tx_skb = NULL;
+
+	tty_driver_flush_buffer(tty);
+	return;
+}
+
+static struct tty_ldisc_ops st_ldisc_ops = {
+	.magic = TTY_LDISC_MAGIC,
+	.name = "n_st",
+	.open = st_tty_open,
+	.close = st_tty_close,
+	.receive_buf = st_tty_receive,
+	.write_wakeup = st_tty_wakeup,
+	.flush_buffer = st_tty_flush_buffer,
+	.owner = THIS_MODULE
+};
+
+/********************************************************************/
+int st_core_init(struct st_data_s **core_data)
+{
+	struct st_data_s *st_gdata;
+	long err;
+
+	err = tty_register_ldisc(N_TI_WL, &st_ldisc_ops);
+	if (err) {
+		pr_err("error registering %d line discipline %ld",
+			   N_TI_WL, err);
+		return err;
+	}
+	pr_debug("registered n_shared line discipline");
+
+	st_gdata = kzalloc(sizeof(struct st_data_s), GFP_KERNEL);
+	if (!st_gdata) {
+		pr_err("memory allocation failed");
+		err = tty_unregister_ldisc(N_TI_WL);
+		if (err)
+			pr_err("unable to un-register ldisc %ld", err);
+		err = -ENOMEM;
+		return err;
+	}
+
+	/* Initialize ST TxQ and Tx waitQ queue head. All BT/FM/GPS module skb's
+	 * will be pushed in this queue for actual transmission.
+	 */
+	skb_queue_head_init(&st_gdata->txq);
+	skb_queue_head_init(&st_gdata->tx_waitq);
+
+	/* Locking used in st_int_enqueue() to avoid multiple execution */
+	spin_lock_init(&st_gdata->lock);
+
+	err = st_ll_init(st_gdata);
+	if (err) {
+		pr_err("error during st_ll initialization(%ld)", err);
+		kfree(st_gdata);
+		err = tty_unregister_ldisc(N_TI_WL);
+		if (err)
+			pr_err("unable to un-register ldisc");
+		return err;
+	}
+
+	INIT_WORK(&st_gdata->work_write_wakeup, work_fn_write_wakeup);
+
+	*core_data = st_gdata;
+	return 0;
+}
+
+void st_core_exit(struct st_data_s *st_gdata)
+{
+	long err;
+	/* internal module cleanup */
+	err = st_ll_deinit(st_gdata);
+	if (err)
+		pr_err("error during deinit of ST LL %ld", err);
+
+	if (st_gdata != NULL) {
+		/* Free ST Tx Qs and skbs */
+		skb_queue_purge(&st_gdata->txq);
+		skb_queue_purge(&st_gdata->tx_waitq);
+		kfree_skb(st_gdata->rx_skb);
+		kfree_skb(st_gdata->tx_skb);
+		/* TTY ldisc cleanup */
+		err = tty_unregister_ldisc(N_TI_WL);
+		if (err)
+			pr_err("unable to un-register ldisc %ld", err);
+		/* free the global data pointer */
+		kfree(st_gdata);
+	}
+}