// 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);
}

/* 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 = le32_to_cpu(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->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 = cpu_to_le32(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;
}