Merge branch 'iosm-driver'

M Chetan Kumar says:

====================
net: iosm: PCIe Driver for Intel M.2 Modem

The IOSM (IPC over Shared Memory) driver is a PCIe host driver implemented
for linux or chrome platform for data exchange over PCIe interface between
Host platform & Intel M.2 Modem. The driver exposes interface conforming to
the MBIM protocol. Any front end application ( eg: Modem Manager) could
easily manage the MBIM interface to enable data communication towards WWAN.

Intel M.2 modem uses 2 BAR regions. The first region is dedicated to Doorbell
register for IRQs and the second region is used as scratchpad area for book
keeping modem execution stage details along with host system shared memory
region context details. The upper edge of the driver exposes the control and
data channels for user space application interaction. At lower edge these data
and control channels are associated to pipes. The pipes are lowest level
interfaces used over PCIe as a logical channel for message exchange. A single
channel maps to UL and DL pipe and are initialized on device open.

On UL path, driver copies application sent data to SKBs associate it with
transfer descriptor and puts it on to ring buffer for DMA transfer. Once
information has been updated in shared memory region, host gives a Doorbell
to modem to perform DMA and modem uses MSI to communicate back to host.
For receiving data in DL path, SKBs are pre-allocated during pipe open and
transfer descriptors are given to modem for DMA transfer.

The driver exposes two types of ports, namely "wwan0mbim0", a char device node
which is used for MBIM control operation and "wwan0-x",(x = 0,1,2..7) network
interfaces for IP data communication.
1) MBIM Control Interface:
This node exposes an interface between modem and application using char device
exposed by "IOSM" driver to establish and manage the MBIM data communication
with PCIe based Intel M.2 Modems.

2) MBIM Data Interface:
The IOSM driver exposes IP link interface "wwan0-x" of type "wwan" for IP traffic.
Iproute network utility is used for creating "wwan0-x" network interface and for
associating it with MBIM IP session. The Driver supports upto 8 IP sessions for
simultaneous IP communication.

This applies on top of WWAN core rtnetlink series posted here:
https://lore.kernel.org/netdev/1623486057-13075-1-git-send-email-loic.poulain@linaro.org/

Also driver has been compiled and tested on top of netdev net-next tree.
https://git.kernel.org/pub/scm/linux/kernel/git/netdev/net-next.git/
====================

Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 910 insertions, 0 deletions

diff --git a/drivers/net/wwan/iosm/iosm_ipc_mux_codec.c b/drivers/net/wwan/iosm/iosm_ipc_mux_codec.c
new file mode 100644
index 000000000000..fbf3cab3394c
--- /dev/null
+++ b/drivers/net/wwan/iosm/iosm_ipc_mux_codec.c
@@ -0,0 +1,910 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright (C) 2020-21 Intel Corporation.
+ */
+
+#include <linux/nospec.h>
+
+#include "iosm_ipc_imem_ops.h"
+#include "iosm_ipc_mux_codec.h"
+#include "iosm_ipc_task_queue.h"
+
+/* Test the link power state and send a MUX command in blocking mode. */
+static int ipc_mux_tq_cmd_send(struct iosm_imem *ipc_imem, int arg, void *msg,
+			       size_t size)
+{
+	struct iosm_mux *ipc_mux = ipc_imem->mux;
+	const struct mux_acb *acb = msg;
+
+	skb_queue_tail(&ipc_mux->channel->ul_list, acb->skb);
+	ipc_imem_ul_send(ipc_mux->imem);
+
+	return 0;
+}
+
+static int ipc_mux_acb_send(struct iosm_mux *ipc_mux, bool blocking)
+{
+	struct completion *completion = &ipc_mux->channel->ul_sem;
+	int ret = ipc_task_queue_send_task(ipc_mux->imem, ipc_mux_tq_cmd_send,
+					   0, &ipc_mux->acb,
+					   sizeof(ipc_mux->acb), false);
+	if (ret) {
+		dev_err(ipc_mux->dev, "unable to send mux command");
+		return ret;
+	}
+
+	/* if blocking, suspend the app and wait for irq in the flash or
+	 * crash phase. return false on timeout to indicate failure.
+	 */
+	if (blocking) {
+		u32 wait_time_milliseconds = IPC_MUX_CMD_RUN_DEFAULT_TIMEOUT;
+
+		reinit_completion(completion);
+
+		if (wait_for_completion_interruptible_timeout
+		   (completion, msecs_to_jiffies(wait_time_milliseconds)) ==
+		   0) {
+			dev_err(ipc_mux->dev, "ch[%d] timeout",
+				ipc_mux->channel_id);
+			ipc_uevent_send(ipc_mux->imem->dev, UEVENT_MDM_TIMEOUT);
+			return -ETIMEDOUT;
+		}
+	}
+
+	return 0;
+}
+
+/* Prepare mux Command */
+static struct mux_lite_cmdh *ipc_mux_lite_add_cmd(struct iosm_mux *ipc_mux,
+						  u32 cmd, struct mux_acb *acb,
+						  void *param, u32 param_size)
+{
+	struct mux_lite_cmdh *cmdh = (struct mux_lite_cmdh *)acb->skb->data;
+
+	cmdh->signature = cpu_to_le32(MUX_SIG_CMDH);
+	cmdh->command_type = cpu_to_le32(cmd);
+	cmdh->if_id = acb->if_id;
+
+	acb->cmd = cmd;
+
+	cmdh->cmd_len = cpu_to_le16(offsetof(struct mux_lite_cmdh, param) +
+				    param_size);
+	cmdh->transaction_id = cpu_to_le32(ipc_mux->tx_transaction_id++);
+
+	if (param)
+		memcpy(&cmdh->param, param, param_size);
+
+	skb_put(acb->skb, le16_to_cpu(cmdh->cmd_len));
+
+	return cmdh;
+}
+
+static int ipc_mux_acb_alloc(struct iosm_mux *ipc_mux)
+{
+	struct mux_acb *acb = &ipc_mux->acb;
+	struct sk_buff *skb;
+	dma_addr_t mapping;
+
+	/* Allocate skb memory for the uplink buffer. */
+	skb = ipc_pcie_alloc_skb(ipc_mux->pcie, MUX_MAX_UL_ACB_BUF_SIZE,
+				 GFP_ATOMIC, &mapping, DMA_TO_DEVICE, 0);
+	if (!skb)
+		return -ENOMEM;
+
+	/* Save the skb address. */
+	acb->skb = skb;
+
+	memset(skb->data, 0, MUX_MAX_UL_ACB_BUF_SIZE);
+
+	return 0;
+}
+
+int ipc_mux_dl_acb_send_cmds(struct iosm_mux *ipc_mux, u32 cmd_type, u8 if_id,
+			     u32 transaction_id, union mux_cmd_param *param,
+			     size_t res_size, bool blocking, bool respond)
+{
+	struct mux_acb *acb = &ipc_mux->acb;
+	struct mux_lite_cmdh *ack_lite;
+	int ret = 0;
+
+	acb->if_id = if_id;
+	ret = ipc_mux_acb_alloc(ipc_mux);
+	if (ret)
+		return ret;
+
+	ack_lite = ipc_mux_lite_add_cmd(ipc_mux, cmd_type, acb, param,
+					res_size);
+	if (respond)
+		ack_lite->transaction_id = cpu_to_le32(transaction_id);
+
+	ret = ipc_mux_acb_send(ipc_mux, blocking);
+
+	return ret;
+}
+
+void ipc_mux_netif_tx_flowctrl(struct mux_session *session, int idx, bool on)
+{
+	/* Inform the network interface to start/stop flow ctrl */
+	ipc_wwan_tx_flowctrl(session->wwan, idx, on);
+}
+
+static int ipc_mux_dl_cmdresps_decode_process(struct iosm_mux *ipc_mux,
+					      struct mux_lite_cmdh *cmdh)
+{
+	struct mux_acb *acb = &ipc_mux->acb;
+
+	switch (le32_to_cpu(cmdh->command_type)) {
+	case MUX_CMD_OPEN_SESSION_RESP:
+	case MUX_CMD_CLOSE_SESSION_RESP:
+		/* Resume the control application. */
+		acb->got_param = cmdh->param;
+		break;
+
+	case MUX_LITE_CMD_FLOW_CTL_ACK:
+		/* This command type is not expected as response for
+		 * Aggregation version of the protocol. So return non-zero.
+		 */
+		if (ipc_mux->protocol != MUX_LITE)
+			return -EINVAL;
+
+		dev_dbg(ipc_mux->dev, "if %u FLOW_CTL_ACK %u received",
+			cmdh->if_id, le32_to_cpu(cmdh->transaction_id));
+		break;
+
+	default:
+		return -EINVAL;
+	}
+
+	acb->wanted_response = MUX_CMD_INVALID;
+	acb->got_response = le32_to_cpu(cmdh->command_type);
+	complete(&ipc_mux->channel->ul_sem);
+
+	return 0;
+}
+
+static int ipc_mux_dl_dlcmds_decode_process(struct iosm_mux *ipc_mux,
+					    struct mux_lite_cmdh *cmdh)
+{
+	union mux_cmd_param *param = &cmdh->param;
+	struct mux_session *session;
+	int new_size;
+
+	dev_dbg(ipc_mux->dev, "if_id[%d]: dlcmds decode process %d",
+		cmdh->if_id, le32_to_cpu(cmdh->command_type));
+
+	switch (le32_to_cpu(cmdh->command_type)) {
+	case MUX_LITE_CMD_FLOW_CTL:
+
+		if (cmdh->if_id >= ipc_mux->nr_sessions) {
+			dev_err(ipc_mux->dev, "if_id [%d] not valid",
+				cmdh->if_id);
+			return -EINVAL; /* No session interface id. */
+		}
+
+		session = &ipc_mux->session[cmdh->if_id];
+
+		new_size = offsetof(struct mux_lite_cmdh, param) +
+			   sizeof(param->flow_ctl);
+		if (param->flow_ctl.mask == cpu_to_le32(0xFFFFFFFF)) {
+			/* Backward Compatibility */
+			if (cmdh->cmd_len == cpu_to_le16(new_size))
+				session->flow_ctl_mask =
+					le32_to_cpu(param->flow_ctl.mask);
+			else
+				session->flow_ctl_mask = ~0;
+			/* if CP asks for FLOW CTRL Enable
+			 * then set our internal flow control Tx flag
+			 * to limit uplink session queueing
+			 */
+			session->net_tx_stop = true;
+			/* Update the stats */
+			session->flow_ctl_en_cnt++;
+		} else if (param->flow_ctl.mask == 0) {
+			/* Just reset the Flow control mask and let
+			 * mux_flow_ctrl_low_thre_b take control on
+			 * our internal Tx flag and enabling kernel
+			 * flow control
+			 */
+			/* Backward Compatibility */
+			if (cmdh->cmd_len == cpu_to_le16(new_size))
+				session->flow_ctl_mask =
+					le32_to_cpu(param->flow_ctl.mask);
+			else
+				session->flow_ctl_mask = 0;
+			/* Update the stats */
+			session->flow_ctl_dis_cnt++;
+		} else {
+			break;
+		}
+
+		dev_dbg(ipc_mux->dev, "if[%u] FLOW CTRL 0x%08X", cmdh->if_id,
+			le32_to_cpu(param->flow_ctl.mask));
+		break;
+
+	case MUX_LITE_CMD_LINK_STATUS_REPORT:
+		break;
+
+	default:
+		return -EINVAL;
+	}
+	return 0;
+}
+
+/* Decode and Send appropriate response to a command block. */
+static void ipc_mux_dl_cmd_decode(struct iosm_mux *ipc_mux, struct sk_buff *skb)
+{
+	struct mux_lite_cmdh *cmdh = (struct mux_lite_cmdh *)skb->data;
+	__le32 trans_id = cmdh->transaction_id;
+
+	if (ipc_mux_dl_cmdresps_decode_process(ipc_mux, cmdh)) {
+		/* Unable to decode command response indicates the cmd_type
+		 * may be a command instead of response. So try to decoding it.
+		 */
+		if (!ipc_mux_dl_dlcmds_decode_process(ipc_mux, cmdh)) {
+			/* Decoded command may need a response. Give the
+			 * response according to the command type.
+			 */
+			union mux_cmd_param *mux_cmd = NULL;
+			size_t size = 0;
+			u32 cmd = MUX_LITE_CMD_LINK_STATUS_REPORT_RESP;
+
+			if (cmdh->command_type ==
+			    cpu_to_le32(MUX_LITE_CMD_LINK_STATUS_REPORT)) {
+				mux_cmd = &cmdh->param;
+				mux_cmd->link_status_resp.response =
+					cpu_to_le32(MUX_CMD_RESP_SUCCESS);
+				/* response field is u32 */
+				size = sizeof(u32);
+			} else if (cmdh->command_type ==
+				   cpu_to_le32(MUX_LITE_CMD_FLOW_CTL)) {
+				cmd = MUX_LITE_CMD_FLOW_CTL_ACK;
+			} else {
+				return;
+			}
+
+			if (ipc_mux_dl_acb_send_cmds(ipc_mux, cmd, cmdh->if_id,
+						     le32_to_cpu(trans_id),
+						     mux_cmd, size, false,
+						     true))
+				dev_err(ipc_mux->dev,
+					"if_id %d: cmd send failed",
+					cmdh->if_id);
+		}
+	}
+}
+
+/* Pass the DL packet to the netif layer. */
+static int ipc_mux_net_receive(struct iosm_mux *ipc_mux, int if_id,
+			       struct iosm_wwan *wwan, u32 offset,
+			       u8 service_class, struct sk_buff *skb)
+{
+	struct sk_buff *dest_skb = skb_clone(skb, GFP_ATOMIC);
+
+	if (!dest_skb)
+		return -ENOMEM;
+
+	skb_pull(dest_skb, offset);
+	skb_set_tail_pointer(dest_skb, dest_skb->len);
+	/* Pass the packet to the netif layer. */
+	dest_skb->priority = service_class;
+
+	return ipc_wwan_receive(wwan, dest_skb, false, if_id + 1);
+}
+
+/* Decode Flow Credit Table in the block */
+static void ipc_mux_dl_fcth_decode(struct iosm_mux *ipc_mux,
+				   unsigned char *block)
+{
+	struct ipc_mem_lite_gen_tbl *fct = (struct ipc_mem_lite_gen_tbl *)block;
+	struct iosm_wwan *wwan;
+	int ul_credits;
+	int if_id;
+
+	if (fct->vfl_length != sizeof(fct->vfl.nr_of_bytes)) {
+		dev_err(ipc_mux->dev, "unexpected FCT length: %d",
+			fct->vfl_length);
+		return;
+	}
+
+	if_id = fct->if_id;
+	if (if_id >= ipc_mux->nr_sessions) {
+		dev_err(ipc_mux->dev, "not supported if_id: %d", if_id);
+		return;
+	}
+
+	/* Is the session active ? */
+	if_id = array_index_nospec(if_id, ipc_mux->nr_sessions);
+	wwan = ipc_mux->session[if_id].wwan;
+	if (!wwan) {
+		dev_err(ipc_mux->dev, "session Net ID is NULL");
+		return;
+	}
+
+	ul_credits = fct->vfl.nr_of_bytes;
+
+	dev_dbg(ipc_mux->dev, "Flow_Credit:: if_id[%d] Old: %d Grants: %d",
+		if_id, ipc_mux->session[if_id].ul_flow_credits, ul_credits);
+
+	/* Update the Flow Credit information from ADB */
+	ipc_mux->session[if_id].ul_flow_credits += ul_credits;
+
+	/* Check whether the TX can be started */
+	if (ipc_mux->session[if_id].ul_flow_credits > 0) {
+		ipc_mux->session[if_id].net_tx_stop = false;
+		ipc_mux_netif_tx_flowctrl(&ipc_mux->session[if_id],
+					  ipc_mux->session[if_id].if_id, false);
+	}
+}
+
+/* Decode non-aggregated datagram */
+static void ipc_mux_dl_adgh_decode(struct iosm_mux *ipc_mux,
+				   struct sk_buff *skb)
+{
+	u32 pad_len, packet_offset;
+	struct iosm_wwan *wwan;
+	struct mux_adgh *adgh;
+	u8 *block = skb->data;
+	int rc = 0;
+	u8 if_id;
+
+	adgh = (struct mux_adgh *)block;
+
+	if (adgh->signature != cpu_to_le32(MUX_SIG_ADGH)) {
+		dev_err(ipc_mux->dev, "invalid ADGH signature received");
+		return;
+	}
+
+	if_id = adgh->if_id;
+	if (if_id >= ipc_mux->nr_sessions) {
+		dev_err(ipc_mux->dev, "invalid if_id while decoding %d", if_id);
+		return;
+	}
+
+	/* Is the session active ? */
+	if_id = array_index_nospec(if_id, ipc_mux->nr_sessions);
+	wwan = ipc_mux->session[if_id].wwan;
+	if (!wwan) {
+		dev_err(ipc_mux->dev, "session Net ID is NULL");
+		return;
+	}
+
+	/* Store the pad len for the corresponding session
+	 * Pad bytes as negotiated in the open session less the header size
+	 * (see session management chapter for details).
+	 * If resulting padding is zero or less, the additional head padding is
+	 * omitted. For e.g., if HEAD_PAD_LEN = 16 or less, this field is
+	 * omitted if HEAD_PAD_LEN = 20, then this field will have 4 bytes
+	 * set to zero
+	 */
+	pad_len =
+		ipc_mux->session[if_id].dl_head_pad_len - IPC_MEM_DL_ETH_OFFSET;
+	packet_offset = sizeof(*adgh) + pad_len;
+
+	if_id += ipc_mux->wwan_q_offset;
+
+	/* Pass the packet to the netif layer */
+	rc = ipc_mux_net_receive(ipc_mux, if_id, wwan, packet_offset,
+				 adgh->service_class, skb);
+	if (rc) {
+		dev_err(ipc_mux->dev, "mux adgh decoding error");
+		return;
+	}
+	ipc_mux->session[if_id].flush = 1;
+}
+
+void ipc_mux_dl_decode(struct iosm_mux *ipc_mux, struct sk_buff *skb)
+{
+	u32 signature;
+
+	if (!skb->data)
+		return;
+
+	/* Decode the MUX header type. */
+	signature = le32_to_cpup((__le32 *)skb->data);
+
+	switch (signature) {
+	case MUX_SIG_ADGH:
+		ipc_mux_dl_adgh_decode(ipc_mux, skb);
+		break;
+
+	case MUX_SIG_FCTH:
+		ipc_mux_dl_fcth_decode(ipc_mux, skb->data);
+		break;
+
+	case MUX_SIG_CMDH:
+		ipc_mux_dl_cmd_decode(ipc_mux, skb);
+		break;
+
+	default:
+		dev_err(ipc_mux->dev, "invalid ABH signature");
+	}
+
+	ipc_pcie_kfree_skb(ipc_mux->pcie, skb);
+}
+
+static int ipc_mux_ul_skb_alloc(struct iosm_mux *ipc_mux,
+				struct mux_adb *ul_adb, u32 type)
+{
+	/* Take the first element of the free list. */
+	struct sk_buff *skb = skb_dequeue(&ul_adb->free_list);
+	int qlt_size;
+
+	if (!skb)
+		return -EBUSY; /* Wait for a free ADB skb. */
+
+	/* Mark it as UL ADB to select the right free operation. */
+	IPC_CB(skb)->op_type = (u8)UL_MUX_OP_ADB;
+
+	switch (type) {
+	case MUX_SIG_ADGH:
+		/* Save the ADB memory settings. */
+		ul_adb->dest_skb = skb;
+		ul_adb->buf = skb->data;
+		ul_adb->size = IPC_MEM_MAX_DL_MUX_LITE_BUF_SIZE;
+		/* reset statistic counter */
+		ul_adb->if_cnt = 0;
+		ul_adb->payload_size = 0;
+		ul_adb->dg_cnt_total = 0;
+
+		ul_adb->adgh = (struct mux_adgh *)skb->data;
+		memset(ul_adb->adgh, 0, sizeof(struct mux_adgh));
+		break;
+
+	case MUX_SIG_QLTH:
+		qlt_size = offsetof(struct ipc_mem_lite_gen_tbl, vfl) +
+			   (MUX_QUEUE_LEVEL * sizeof(struct mux_lite_vfl));
+
+		if (qlt_size > IPC_MEM_MAX_DL_MUX_LITE_BUF_SIZE) {
+			dev_err(ipc_mux->dev,
+				"can't support. QLT size:%d SKB size: %d",
+				qlt_size, IPC_MEM_MAX_DL_MUX_LITE_BUF_SIZE);
+			return -ERANGE;
+		}
+
+		ul_adb->qlth_skb = skb;
+		memset((ul_adb->qlth_skb)->data, 0, qlt_size);
+		skb_put(skb, qlt_size);
+		break;
+	}
+
+	return 0;
+}
+
+static void ipc_mux_ul_adgh_finish(struct iosm_mux *ipc_mux)
+{
+	struct mux_adb *ul_adb = &ipc_mux->ul_adb;
+	u16 adgh_len;
+	long long bytes;
+	char *str;
+
+	if (!ul_adb || !ul_adb->dest_skb) {
+		dev_err(ipc_mux->dev, "no dest skb");
+		return;
+	}
+
+	adgh_len = le16_to_cpu(ul_adb->adgh->length);
+	skb_put(ul_adb->dest_skb, adgh_len);
+	skb_queue_tail(&ipc_mux->channel->ul_list, ul_adb->dest_skb);
+	ul_adb->dest_skb = NULL;
+
+	if (ipc_mux->ul_flow == MUX_UL_ON_CREDITS) {
+		struct mux_session *session;
+
+		session = &ipc_mux->session[ul_adb->adgh->if_id];
+		str = "available_credits";
+		bytes = (long long)session->ul_flow_credits;
+
+	} else {
+		str = "pend_bytes";
+		bytes = ipc_mux->ul_data_pend_bytes;
+		ipc_mux->ul_data_pend_bytes = ipc_mux->ul_data_pend_bytes +
+					      adgh_len;
+	}
+
+	dev_dbg(ipc_mux->dev, "UL ADGH: size=%u, if_id=%d, payload=%d, %s=%lld",
+		adgh_len, ul_adb->adgh->if_id, ul_adb->payload_size,
+		str, bytes);
+}
+
+/* Allocates an ADB from the free list and initializes it with ADBH  */
+static bool ipc_mux_ul_adb_allocate(struct iosm_mux *ipc_mux,
+				    struct mux_adb *adb, int *size_needed,
+				    u32 type)
+{
+	bool ret_val = false;
+	int status;
+
+	if (!adb->dest_skb) {
+		/* Allocate memory for the ADB including of the
+		 * datagram table header.
+		 */
+		status = ipc_mux_ul_skb_alloc(ipc_mux, adb, type);
+		if (status)
+			/* Is a pending ADB available ? */
+			ret_val = true; /* None. */
+
+		/* Update size need to zero only for new ADB memory */
+		*size_needed = 0;
+	}
+
+	return ret_val;
+}
+
+/* Informs the network stack to stop sending further packets for all opened
+ * sessions
+ */
+static void ipc_mux_stop_tx_for_all_sessions(struct iosm_mux *ipc_mux)
+{
+	struct mux_session *session;
+	int idx;
+
+	for (idx = 0; idx < ipc_mux->nr_sessions; idx++) {
+		session = &ipc_mux->session[idx];
+
+		if (!session->wwan)
+			continue;
+
+		session->net_tx_stop = true;
+	}
+}
+
+/* Sends Queue Level Table of all opened sessions */
+static bool ipc_mux_lite_send_qlt(struct iosm_mux *ipc_mux)
+{
+	struct ipc_mem_lite_gen_tbl *qlt;
+	struct mux_session *session;
+	bool qlt_updated = false;
+	int i;
+	int qlt_size;
+
+	if (!ipc_mux->initialized || ipc_mux->state != MUX_S_ACTIVE)
+		return qlt_updated;
+
+	qlt_size = offsetof(struct ipc_mem_lite_gen_tbl, vfl) +
+		   MUX_QUEUE_LEVEL * sizeof(struct mux_lite_vfl);
+
+	for (i = 0; i < ipc_mux->nr_sessions; i++) {
+		session = &ipc_mux->session[i];
+
+		if (!session->wwan || session->flow_ctl_mask)
+			continue;
+
+		if (ipc_mux_ul_skb_alloc(ipc_mux, &ipc_mux->ul_adb,
+					 MUX_SIG_QLTH)) {
+			dev_err(ipc_mux->dev,
+				"no reserved mem to send QLT of if_id: %d", i);
+			break;
+		}
+
+		/* Prepare QLT */
+		qlt = (struct ipc_mem_lite_gen_tbl *)(ipc_mux->ul_adb.qlth_skb)
+			      ->data;
+		qlt->signature = cpu_to_le32(MUX_SIG_QLTH);
+		qlt->length = cpu_to_le16(qlt_size);
+		qlt->if_id = i;
+		qlt->vfl_length = MUX_QUEUE_LEVEL * sizeof(struct mux_lite_vfl);
+		qlt->reserved[0] = 0;
+		qlt->reserved[1] = 0;
+
+		qlt->vfl.nr_of_bytes = session->ul_list.qlen;
+
+		/* Add QLT to the transfer list. */
+		skb_queue_tail(&ipc_mux->channel->ul_list,
+			       ipc_mux->ul_adb.qlth_skb);
+
+		qlt_updated = true;
+		ipc_mux->ul_adb.qlth_skb = NULL;
+	}
+
+	if (qlt_updated)
+		/* Updates the TDs with ul_list */
+		(void)ipc_imem_ul_write_td(ipc_mux->imem);
+
+	return qlt_updated;
+}
+
+/* Checks the available credits for the specified session and returns
+ * number of packets for which credits are available.
+ */
+static int ipc_mux_ul_bytes_credits_check(struct iosm_mux *ipc_mux,
+					  struct mux_session *session,
+					  struct sk_buff_head *ul_list,
+					  int max_nr_of_pkts)
+{
+	int pkts_to_send = 0;
+	struct sk_buff *skb;
+	int credits = 0;
+
+	if (ipc_mux->ul_flow == MUX_UL_ON_CREDITS) {
+		credits = session->ul_flow_credits;
+		if (credits <= 0) {
+			dev_dbg(ipc_mux->dev,
+				"FC::if_id[%d] Insuff.Credits/Qlen:%d/%u",
+				session->if_id, session->ul_flow_credits,
+				session->ul_list.qlen); /* nr_of_bytes */
+			return 0;
+		}
+	} else {
+		credits = IPC_MEM_MUX_UL_FLOWCTRL_HIGH_B -
+			  ipc_mux->ul_data_pend_bytes;
+		if (credits <= 0) {
+			ipc_mux_stop_tx_for_all_sessions(ipc_mux);
+
+			dev_dbg(ipc_mux->dev,
+				"if_id[%d] encod. fail Bytes: %llu, thresh: %d",
+				session->if_id, ipc_mux->ul_data_pend_bytes,
+				IPC_MEM_MUX_UL_FLOWCTRL_HIGH_B);
+			return 0;
+		}
+	}
+
+	/* Check if there are enough credits/bytes available to send the
+	 * requested max_nr_of_pkts. Otherwise restrict the nr_of_pkts
+	 * depending on available credits.
+	 */
+	skb_queue_walk(ul_list, skb)
+	{
+		if (!(credits >= skb->len && pkts_to_send < max_nr_of_pkts))
+			break;
+		credits -= skb->len;
+		pkts_to_send++;
+	}
+
+	return pkts_to_send;
+}
+
+/* Encode the UL IP packet according to Lite spec. */
+static int ipc_mux_ul_adgh_encode(struct iosm_mux *ipc_mux, int session_id,
+				  struct mux_session *session,
+				  struct sk_buff_head *ul_list,
+				  struct mux_adb *adb, int nr_of_pkts)
+{
+	int offset = sizeof(struct mux_adgh);
+	int adb_updated = -EINVAL;
+	struct sk_buff *src_skb;
+	int aligned_size = 0;
+	int nr_of_skb = 0;
+	u32 pad_len = 0;
+
+	/* Re-calculate the number of packets depending on number of bytes to be
+	 * processed/available credits.
+	 */
+	nr_of_pkts = ipc_mux_ul_bytes_credits_check(ipc_mux, session, ul_list,
+						    nr_of_pkts);
+
+	/* If calculated nr_of_pkts from available credits is <= 0
+	 * then nothing to do.
+	 */
+	if (nr_of_pkts <= 0)
+		return 0;
+
+	/* Read configured UL head_pad_length for session.*/
+	if (session->ul_head_pad_len > IPC_MEM_DL_ETH_OFFSET)
+		pad_len = session->ul_head_pad_len - IPC_MEM_DL_ETH_OFFSET;
+
+	/* Process all pending UL packets for this session
+	 * depending on the allocated datagram table size.
+	 */
+	while (nr_of_pkts > 0) {
+		/* get destination skb allocated */
+		if (ipc_mux_ul_adb_allocate(ipc_mux, adb, &ipc_mux->size_needed,
+					    MUX_SIG_ADGH)) {
+			dev_err(ipc_mux->dev, "no reserved memory for ADGH");
+			return -ENOMEM;
+		}
+
+		/* Peek at the head of the list. */
+		src_skb = skb_peek(ul_list);
+		if (!src_skb) {
+			dev_err(ipc_mux->dev,
+				"skb peek return NULL with count : %d",
+				nr_of_pkts);
+			break;
+		}
+
+		/* Calculate the memory value. */
+		aligned_size = ALIGN((pad_len + src_skb->len), 4);
+
+		ipc_mux->size_needed = sizeof(struct mux_adgh) + aligned_size;
+
+		if (ipc_mux->size_needed > adb->size) {
+			dev_dbg(ipc_mux->dev, "size needed %d, adgh size %d",
+				ipc_mux->size_needed, adb->size);
+			/* Return 1 if any IP packet is added to the transfer
+			 * list.
+			 */
+			return nr_of_skb ? 1 : 0;
+		}
+
+		/* Add buffer (without head padding to next pending transfer) */
+		memcpy(adb->buf + offset + pad_len, src_skb->data,
+		       src_skb->len);
+
+		adb->adgh->signature = cpu_to_le32(MUX_SIG_ADGH);
+		adb->adgh->if_id = session_id;
+		adb->adgh->length =
+			cpu_to_le16(sizeof(struct mux_adgh) + pad_len +
+				    src_skb->len);
+		adb->adgh->service_class = src_skb->priority;
+		adb->adgh->next_count = --nr_of_pkts;
+		adb->dg_cnt_total++;
+		adb->payload_size += src_skb->len;
+
+		if (ipc_mux->ul_flow == MUX_UL_ON_CREDITS)
+			/* Decrement the credit value as we are processing the
+			 * datagram from the UL list.
+			 */
+			session->ul_flow_credits -= src_skb->len;
+
+		/* Remove the processed elements and free it. */
+		src_skb = skb_dequeue(ul_list);
+		dev_kfree_skb(src_skb);
+		nr_of_skb++;
+
+		ipc_mux_ul_adgh_finish(ipc_mux);
+	}
+
+	if (nr_of_skb) {
+		/* Send QLT info to modem if pending bytes > high watermark
+		 * in case of mux lite
+		 */
+		if (ipc_mux->ul_flow == MUX_UL_ON_CREDITS ||
+		    ipc_mux->ul_data_pend_bytes >=
+			    IPC_MEM_MUX_UL_FLOWCTRL_LOW_B)
+			adb_updated = ipc_mux_lite_send_qlt(ipc_mux);
+		else
+			adb_updated = 1;
+
+		/* Updates the TDs with ul_list */
+		(void)ipc_imem_ul_write_td(ipc_mux->imem);
+	}
+
+	return adb_updated;
+}
+
+bool ipc_mux_ul_data_encode(struct iosm_mux *ipc_mux)
+{
+	struct sk_buff_head *ul_list;
+	struct mux_session *session;
+	int updated = 0;
+	int session_id;
+	int dg_n;
+	int i;
+
+	if (!ipc_mux || ipc_mux->state != MUX_S_ACTIVE ||
+	    ipc_mux->adb_prep_ongoing)
+		return false;
+
+	ipc_mux->adb_prep_ongoing = true;
+
+	for (i = 0; i < ipc_mux->nr_sessions; i++) {
+		session_id = ipc_mux->rr_next_session;
+		session = &ipc_mux->session[session_id];
+
+		/* Go to next handle rr_next_session overflow */
+		ipc_mux->rr_next_session++;
+		if (ipc_mux->rr_next_session >= ipc_mux->nr_sessions)
+			ipc_mux->rr_next_session = 0;
+
+		if (!session->wwan || session->flow_ctl_mask ||
+		    session->net_tx_stop)
+			continue;
+
+		ul_list = &session->ul_list;
+
+		/* Is something pending in UL and flow ctrl off */
+		dg_n = skb_queue_len(ul_list);
+		if (dg_n > MUX_MAX_UL_DG_ENTRIES)
+			dg_n = MUX_MAX_UL_DG_ENTRIES;
+
+		if (dg_n == 0)
+			/* Nothing to do for ipc_mux session
+			 * -> try next session id.
+			 */
+			continue;
+
+		updated = ipc_mux_ul_adgh_encode(ipc_mux, session_id, session,
+						 ul_list, &ipc_mux->ul_adb,
+						 dg_n);
+	}
+
+	ipc_mux->adb_prep_ongoing = false;
+	return updated == 1;
+}
+
+void ipc_mux_ul_encoded_process(struct iosm_mux *ipc_mux, struct sk_buff *skb)
+{
+	struct mux_adgh *adgh;
+	u16 adgh_len;
+
+	adgh = (struct mux_adgh *)skb->data;
+	adgh_len = le16_to_cpu(adgh->length);
+
+	if (adgh->signature == cpu_to_le32(MUX_SIG_ADGH) &&
+	    ipc_mux->ul_flow == MUX_UL)
+		ipc_mux->ul_data_pend_bytes = ipc_mux->ul_data_pend_bytes -
+					      adgh_len;
+
+	if (ipc_mux->ul_flow == MUX_UL)
+		dev_dbg(ipc_mux->dev, "ul_data_pend_bytes: %lld",
+			ipc_mux->ul_data_pend_bytes);
+
+	/* Reset the skb settings. */
+	skb->tail = 0;
+	skb->len = 0;
+
+	/* Add the consumed ADB to the free list. */
+	skb_queue_tail((&ipc_mux->ul_adb.free_list), skb);
+}
+
+/* Start the NETIF uplink send transfer in MUX mode. */
+static int ipc_mux_tq_ul_trigger_encode(struct iosm_imem *ipc_imem, int arg,
+					void *msg, size_t size)
+{
+	struct iosm_mux *ipc_mux = ipc_imem->mux;
+	bool ul_data_pend = false;
+
+	/* Add session UL data to a ADB and ADGH */
+	ul_data_pend = ipc_mux_ul_data_encode(ipc_mux);
+	if (ul_data_pend)
+		/* Delay the doorbell irq */
+		ipc_imem_td_update_timer_start(ipc_mux->imem);
+
+	/* reset the debounce flag */
+	ipc_mux->ev_mux_net_transmit_pending = false;
+
+	return 0;
+}
+
+int ipc_mux_ul_trigger_encode(struct iosm_mux *ipc_mux, int if_id,
+			      struct sk_buff *skb)
+{
+	struct mux_session *session = &ipc_mux->session[if_id];
+	int ret = -EINVAL;
+
+	if (ipc_mux->channel &&
+	    ipc_mux->channel->state != IMEM_CHANNEL_ACTIVE) {
+		dev_err(ipc_mux->dev,
+			"channel state is not IMEM_CHANNEL_ACTIVE");
+		goto out;
+	}
+
+	if (!session->wwan) {
+		dev_err(ipc_mux->dev, "session net ID is NULL");
+		ret = -EFAULT;
+		goto out;
+	}
+
+	/* Session is under flow control.
+	 * Check if packet can be queued in session list, if not
+	 * suspend net tx
+	 */
+	if (skb_queue_len(&session->ul_list) >=
+	    (session->net_tx_stop ?
+		     IPC_MEM_MUX_UL_SESS_FCON_THRESHOLD :
+		     (IPC_MEM_MUX_UL_SESS_FCON_THRESHOLD *
+		      IPC_MEM_MUX_UL_SESS_FCOFF_THRESHOLD_FACTOR))) {
+		ipc_mux_netif_tx_flowctrl(session, session->if_id, true);
+		ret = -EBUSY;
+		goto out;
+	}
+
+	/* Add skb to the uplink skb accumulator. */
+	skb_queue_tail(&session->ul_list, skb);
+
+	/* Inform the IPC kthread to pass uplink IP packets to CP. */
+	if (!ipc_mux->ev_mux_net_transmit_pending) {
+		ipc_mux->ev_mux_net_transmit_pending = true;
+		ret = ipc_task_queue_send_task(ipc_mux->imem,
+					       ipc_mux_tq_ul_trigger_encode, 0,
+					       NULL, 0, false);
+		if (ret)
+			goto out;
+	}
+	dev_dbg(ipc_mux->dev, "mux ul if[%d] qlen=%d/%u, len=%d/%d, prio=%d",
+		if_id, skb_queue_len(&session->ul_list), session->ul_list.qlen,
+		skb->len, skb->truesize, skb->priority);
+	ret = 0;
+out:
+	return ret;
+}