// SPDX-License-Identifier: GPL-2.0-only
/*
 * Copyright (C) 2020-21 Intel Corporation.
 */

#include "iosm_ipc_mux_codec.h"

/* At the begin of the runtime phase the IP MUX channel shall created. */
static int ipc_mux_channel_create(struct iosm_mux *ipc_mux)
{
        int channel_id;

        channel_id = ipc_imem_channel_alloc(ipc_mux->imem, ipc_mux->instance_id,
                                            IPC_CTYPE_WWAN);

        if (channel_id < 0) {
                dev_err(ipc_mux->dev,
                        "allocation of the MUX channel id failed");
                ipc_mux->state = MUX_S_ERROR;
                ipc_mux->event = MUX_E_NOT_APPLICABLE;
                goto no_channel;
        }

        /* Establish the MUX channel in blocking mode. */
        ipc_mux->channel = ipc_imem_channel_open(ipc_mux->imem, channel_id,
                                                 IPC_HP_NET_CHANNEL_INIT);

        if (!ipc_mux->channel) {
                dev_err(ipc_mux->dev, "ipc_imem_channel_open failed");
                ipc_mux->state = MUX_S_ERROR;
                ipc_mux->event = MUX_E_NOT_APPLICABLE;
                return -ENODEV; /* MUX channel is not available. */
        }

        /* Define the MUX active state properties. */
        ipc_mux->state = MUX_S_ACTIVE;
        ipc_mux->event = MUX_E_NO_ORDERS;

no_channel:
        return channel_id;
}

/* Reset the session/if id state. */
static void ipc_mux_session_free(struct iosm_mux *ipc_mux, int if_id)
{
        struct mux_session *if_entry;

        if_entry = &ipc_mux->session[if_id];
        /* Reset the session state. */
        if_entry->wwan = NULL;
}

/* Create and send the session open command. */
static struct mux_cmd_open_session_resp *
ipc_mux_session_open_send(struct iosm_mux *ipc_mux, int if_id)
{
        struct mux_cmd_open_session_resp *open_session_resp;
        struct mux_acb *acb = &ipc_mux->acb;
        union mux_cmd_param param;

        /* open_session commands to one ACB and start transmission. */
        param.open_session.flow_ctrl = 0;
        param.open_session.ipv4v6_hints = 0;
        param.open_session.reserved2 = 0;
        param.open_session.dl_head_pad_len = cpu_to_le32(IPC_MEM_DL_ETH_OFFSET);

        /* Finish and transfer ACB. The user thread is suspended.
         * It is a blocking function call, until CP responds or timeout.
         */
        acb->wanted_response = MUX_CMD_OPEN_SESSION_RESP;
        if (ipc_mux_dl_acb_send_cmds(ipc_mux, MUX_CMD_OPEN_SESSION, if_id, 0,
                                     &param, sizeof(param.open_session), true,
                                 false) ||
            acb->got_response != MUX_CMD_OPEN_SESSION_RESP) {
                dev_err(ipc_mux->dev, "if_id %d: OPEN_SESSION send failed",
                        if_id);
                return NULL;
        }

        open_session_resp = &ipc_mux->acb.got_param.open_session_resp;
        if (open_session_resp->response != cpu_to_le32(MUX_CMD_RESP_SUCCESS)) {
                dev_err(ipc_mux->dev,
                        "if_id %d,session open failed,response=%d", if_id,
                        open_session_resp->response);
                return NULL;
        }

        return open_session_resp;
}

/* Open the first IP session. */
static bool ipc_mux_session_open(struct iosm_mux *ipc_mux,
                                 struct mux_session_open *session_open)
{
        struct mux_cmd_open_session_resp *open_session_resp;
        int if_id;

        /* Search for a free session interface id. */
        if_id = le32_to_cpu(session_open->if_id);
        if (if_id < 0 || if_id >= ipc_mux->nr_sessions) {
                dev_err(ipc_mux->dev, "invalid interface id=%d", if_id);
                return false;
        }

        /* Create and send the session open command.
         * It is a blocking function call, until CP responds or timeout.
         */
        open_session_resp = ipc_mux_session_open_send(ipc_mux, if_id);
        if (!open_session_resp) {
                ipc_mux_session_free(ipc_mux, if_id);
                session_open->if_id = cpu_to_le32(-1);
                return false;
        }

        /* Initialize the uplink skb accumulator. */
        skb_queue_head_init(&ipc_mux->session[if_id].ul_list);

        ipc_mux->session[if_id].dl_head_pad_len = IPC_MEM_DL_ETH_OFFSET;
        ipc_mux->session[if_id].ul_head_pad_len =
                le32_to_cpu(open_session_resp->ul_head_pad_len);
        ipc_mux->session[if_id].wwan = ipc_mux->wwan;

        /* Reset the flow ctrl stats of the session */
        ipc_mux->session[if_id].flow_ctl_en_cnt = 0;
        ipc_mux->session[if_id].flow_ctl_dis_cnt = 0;
        ipc_mux->session[if_id].ul_flow_credits = 0;
        ipc_mux->session[if_id].net_tx_stop = false;
        ipc_mux->session[if_id].flow_ctl_mask = 0;

        /* Save and return the assigned if id. */
        session_open->if_id = cpu_to_le32(if_id);

        return true;
}

/* Free pending session UL packet. */
static void ipc_mux_session_reset(struct iosm_mux *ipc_mux, int if_id)
{
        /* Reset the session/if id state. */
        ipc_mux_session_free(ipc_mux, if_id);

        /* Empty the uplink skb accumulator. */
        skb_queue_purge(&ipc_mux->session[if_id].ul_list);
}

static void ipc_mux_session_close(struct iosm_mux *ipc_mux,
                                  struct mux_session_close *msg)
{
        int if_id;

        /* Copy the session interface id. */
        if_id = le32_to_cpu(msg->if_id);

        if (if_id < 0 || if_id >= ipc_mux->nr_sessions) {
                dev_err(ipc_mux->dev, "invalid session id %d", if_id);
                return;
        }

        /* Create and send the session close command.
         * It is a blocking function call, until CP responds or timeout.
         */
        if (ipc_mux_dl_acb_send_cmds(ipc_mux, MUX_CMD_CLOSE_SESSION, if_id, 0,
                                     NULL, 0, true, false))
                dev_err(ipc_mux->dev, "if_id %d: CLOSE_SESSION send failed",
                        if_id);

        /* Reset the flow ctrl stats of the session */
        ipc_mux->session[if_id].flow_ctl_en_cnt = 0;
        ipc_mux->session[if_id].flow_ctl_dis_cnt = 0;
        ipc_mux->session[if_id].flow_ctl_mask = 0;

        ipc_mux_session_reset(ipc_mux, if_id);
}

static void ipc_mux_channel_close(struct iosm_mux *ipc_mux,
                                  struct mux_channel_close *channel_close_p)
{
        int i;

        /* Free pending session UL packet. */
        for (i = 0; i < ipc_mux->nr_sessions; i++)
                if (ipc_mux->session[i].wwan)
                        ipc_mux_session_reset(ipc_mux, i);

        ipc_imem_channel_close(ipc_mux->imem, ipc_mux->channel_id);

        /* Reset the MUX object. */
        ipc_mux->state = MUX_S_INACTIVE;
        ipc_mux->event = MUX_E_INACTIVE;
}

/* CP has interrupted AP. If AP is in IP MUX mode, execute the pending ops. */
static int ipc_mux_schedule(struct iosm_mux *ipc_mux, union mux_msg *msg)
{
        enum mux_event order;
        bool success;
        int ret = -EIO;

        if (!ipc_mux->initialized) {
                ret = -EAGAIN;
                goto out;
        }

        order = msg->common.event;

        switch (ipc_mux->state) {
        case MUX_S_INACTIVE:
                if (order != MUX_E_MUX_SESSION_OPEN)
                        goto out; /* Wait for the request to open a session */

                if (ipc_mux->event == MUX_E_INACTIVE)
                        /* Establish the MUX channel and the new state. */
                        ipc_mux->channel_id = ipc_mux_channel_create(ipc_mux);

                if (ipc_mux->state != MUX_S_ACTIVE) {
                        ret = ipc_mux->channel_id; /* Missing the MUX channel */
                        goto out;
                }

                /* Disable the TD update timer and open the first IP session. */
                ipc_imem_td_update_timer_suspend(ipc_mux->imem, true);
                ipc_mux->event = MUX_E_MUX_SESSION_OPEN;
                success = ipc_mux_session_open(ipc_mux, &msg->session_open);

                ipc_imem_td_update_timer_suspend(ipc_mux->imem, false);
                if (success)
                        ret = ipc_mux->channel_id;
                goto out;

        case MUX_S_ACTIVE:
                switch (order) {
                case MUX_E_MUX_SESSION_OPEN:
                        /* Disable the TD update timer and open a session */
                        ipc_imem_td_update_timer_suspend(ipc_mux->imem, true);
                        ipc_mux->event = MUX_E_MUX_SESSION_OPEN;
                        success = ipc_mux_session_open(ipc_mux,
                                                       &msg->session_open);
                        ipc_imem_td_update_timer_suspend(ipc_mux->imem, false);
                        if (success)
                                ret = ipc_mux->channel_id;
                        goto out;

                case MUX_E_MUX_SESSION_CLOSE:
                        /* Release an IP session. */
                        ipc_mux->event = MUX_E_MUX_SESSION_CLOSE;
                        ipc_mux_session_close(ipc_mux, &msg->session_close);
                        ret = ipc_mux->channel_id;
                        goto out;

                case MUX_E_MUX_CHANNEL_CLOSE:
                        /* Close the MUX channel pipes. */
                        ipc_mux->event = MUX_E_MUX_CHANNEL_CLOSE;
                        ipc_mux_channel_close(ipc_mux, &msg->channel_close);
                        ret = ipc_mux->channel_id;
                        goto out;

                default:
                        /* Invalid order. */
                        goto out;
                }

        default:
                dev_err(ipc_mux->dev,
                        "unexpected MUX transition: state=%d, event=%d",
                        ipc_mux->state, ipc_mux->event);
        }
out:
        return ret;
}

struct iosm_mux *ipc_mux_init(struct ipc_mux_config *mux_cfg,
                              struct iosm_imem *imem)
{
        struct iosm_mux *ipc_mux = kzalloc(sizeof(*ipc_mux), GFP_KERNEL);
        int i, ul_tds, ul_td_size;
        struct sk_buff_head *free_list;
        struct sk_buff *skb;

        if (!ipc_mux)
                return NULL;

        ipc_mux->protocol = mux_cfg->protocol;
        ipc_mux->ul_flow = mux_cfg->ul_flow;
        ipc_mux->nr_sessions = mux_cfg->nr_sessions;
        ipc_mux->instance_id = mux_cfg->instance_id;
        ipc_mux->wwan_q_offset = 0;

        ipc_mux->pcie = imem->pcie;
        ipc_mux->imem = imem;
        ipc_mux->ipc_protocol = imem->ipc_protocol;
        ipc_mux->dev = imem->dev;
        ipc_mux->wwan = imem->wwan;

        /* Get the reference to the UL ADB list. */
        free_list = &ipc_mux->ul_adb.free_list;

        /* Initialize the list with free ADB. */
        skb_queue_head_init(free_list);

        ul_td_size = IPC_MEM_MAX_DL_MUX_LITE_BUF_SIZE;

        ul_tds = IPC_MEM_MAX_TDS_MUX_LITE_UL;

        ipc_mux->ul_adb.dest_skb = NULL;

        ipc_mux->initialized = true;
        ipc_mux->adb_prep_ongoing = false;
        ipc_mux->size_needed = 0;
        ipc_mux->ul_data_pend_bytes = 0;
        ipc_mux->state = MUX_S_INACTIVE;
        ipc_mux->ev_mux_net_transmit_pending = false;
        ipc_mux->tx_transaction_id = 0;
        ipc_mux->rr_next_session = 0;
        ipc_mux->event = MUX_E_INACTIVE;
        ipc_mux->channel_id = -1;
        ipc_mux->channel = NULL;

        /* Allocate the list of UL ADB. */
        for (i = 0; i < ul_tds; i++) {
                dma_addr_t mapping;

                skb = ipc_pcie_alloc_skb(ipc_mux->pcie, ul_td_size, GFP_ATOMIC,
                                         &mapping, DMA_TO_DEVICE, 0);
                if (!skb) {
                        ipc_mux_deinit(ipc_mux);
                        return NULL;
                }
                /* Extend the UL ADB list. */
                skb_queue_tail(free_list, skb);
        }

        return ipc_mux;
}

/* Informs the network stack to restart transmission for all opened session if
 * Flow Control is not ON for that session.
 */
static void ipc_mux_restart_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;

                /* If flow control of the session is OFF and if there was tx
                 * stop then restart. Inform the network interface to restart
                 * sending data.
                 */
                if (session->flow_ctl_mask == 0) {
                        session->net_tx_stop = false;
                        ipc_mux_netif_tx_flowctrl(session, idx, false);
                }
        }
}

/* Informs the network stack to stop sending further pkt for all opened
 * sessions
 */
static void ipc_mux_stop_netif_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;

                ipc_mux_netif_tx_flowctrl(session, session->if_id, true);
        }
}

void ipc_mux_check_n_restart_tx(struct iosm_mux *ipc_mux)
{
        if (ipc_mux->ul_flow == MUX_UL) {
                int low_thresh = IPC_MEM_MUX_UL_FLOWCTRL_LOW_B;

                if (ipc_mux->ul_data_pend_bytes < low_thresh)
                        ipc_mux_restart_tx_for_all_sessions(ipc_mux);
        }
}

int ipc_mux_get_max_sessions(struct iosm_mux *ipc_mux)
{
        return ipc_mux ? ipc_mux->nr_sessions : -EFAULT;
}

enum ipc_mux_protocol ipc_mux_get_active_protocol(struct iosm_mux *ipc_mux)
{
        return ipc_mux ? ipc_mux->protocol : MUX_UNKNOWN;
}

int ipc_mux_open_session(struct iosm_mux *ipc_mux, int session_nr)
{
        struct mux_session_open *session_open;
        union mux_msg mux_msg;

        session_open = &mux_msg.session_open;
        session_open->event = MUX_E_MUX_SESSION_OPEN;

        session_open->if_id = cpu_to_le32(session_nr);
        ipc_mux->session[session_nr].flags |= IPC_MEM_WWAN_MUX;
        return ipc_mux_schedule(ipc_mux, &mux_msg);
}

int ipc_mux_close_session(struct iosm_mux *ipc_mux, int session_nr)
{
        struct mux_session_close *session_close;
        union mux_msg mux_msg;
        int ret_val;

        session_close = &mux_msg.session_close;
        session_close->event = MUX_E_MUX_SESSION_CLOSE;

        session_close->if_id = cpu_to_le32(session_nr);
        ret_val = ipc_mux_schedule(ipc_mux, &mux_msg);
        ipc_mux->session[session_nr].flags &= ~IPC_MEM_WWAN_MUX;

        return ret_val;
}

void ipc_mux_deinit(struct iosm_mux *ipc_mux)
{
        struct mux_channel_close *channel_close;
        struct sk_buff_head *free_list;
        union mux_msg mux_msg;
        struct sk_buff *skb;

        if (!ipc_mux->initialized)
                return;
        ipc_mux_stop_netif_for_all_sessions(ipc_mux);

        channel_close = &mux_msg.channel_close;
        channel_close->event = MUX_E_MUX_CHANNEL_CLOSE;
        ipc_mux_schedule(ipc_mux, &mux_msg);

        /* Empty the ADB free list. */
        free_list = &ipc_mux->ul_adb.free_list;

        /* Remove from the head of the downlink queue. */
        while ((skb = skb_dequeue(free_list)))
                ipc_pcie_kfree_skb(ipc_mux->pcie, skb);

        if (ipc_mux->channel) {
                ipc_mux->channel->ul_pipe.is_open = false;
                ipc_mux->channel->dl_pipe.is_open = false;
        }

        kfree(ipc_mux);
}