// SPDX-License-Identifier: GPL-2.0-only
/* Copyright (c) 2013-2018, The Linux Foundation. All rights reserved.
 */

#include <linux/netdevice.h>
#include "rmnet_config.h"
#include "rmnet_map.h"
#include "rmnet_private.h"
#include "rmnet_vnd.h"

static u8 rmnet_map_do_flow_control(struct sk_buff *skb,
                                    struct rmnet_port *port,
                                    int enable)
{
        struct rmnet_map_header *map_header = (void *)skb->data;
        struct rmnet_endpoint *ep;
        struct net_device *vnd;
        u8 mux_id;
        int r;

        mux_id = map_header->mux_id;

        if (mux_id >= RMNET_MAX_LOGICAL_EP) {
                kfree_skb(skb);
                return RX_HANDLER_CONSUMED;
        }

        ep = rmnet_get_endpoint(port, mux_id);
        if (!ep) {
                kfree_skb(skb);
                return RX_HANDLER_CONSUMED;
        }

        vnd = ep->egress_dev;

        /* Ignore the ip family and pass the sequence number for both v4 and v6
         * sequence. User space does not support creating dedicated flows for
         * the 2 protocols
         */
        r = rmnet_vnd_do_flow_control(vnd, enable);
        if (r) {
                kfree_skb(skb);
                return RMNET_MAP_COMMAND_UNSUPPORTED;
        } else {
                return RMNET_MAP_COMMAND_ACK;
        }
}

static void rmnet_map_send_ack(struct sk_buff *skb,
                               unsigned char type,
                               struct rmnet_port *port)
{
        struct rmnet_map_header *map_header = (void *)skb->data;
        struct rmnet_map_control_command *cmd;
        struct net_device *dev = skb->dev;

        if (port->data_format & RMNET_FLAGS_INGRESS_MAP_CKSUMV4)
                skb_trim(skb,
                         skb->len - sizeof(struct rmnet_map_dl_csum_trailer));

        skb->protocol = htons(ETH_P_MAP);

        /* Command data immediately follows the MAP header */
        cmd = (struct rmnet_map_control_command *)(map_header + 1);
        cmd->cmd_type = type & 0x03;

        netif_tx_lock(dev);
        dev->netdev_ops->ndo_start_xmit(skb, dev);
        netif_tx_unlock(dev);
}

/* Process MAP command frame and send N/ACK message as appropriate. Message cmd
 * name is decoded here and appropriate handler is called.
 */
void rmnet_map_command(struct sk_buff *skb, struct rmnet_port *port)
{
        struct rmnet_map_header *map_header = (void *)skb->data;
        struct rmnet_map_control_command *cmd;
        unsigned char command_name;
        unsigned char rc = 0;

        /* Command data immediately follows the MAP header */
        cmd = (struct rmnet_map_control_command *)(map_header + 1);
        command_name = cmd->command_name;

        switch (command_name) {
        case RMNET_MAP_COMMAND_FLOW_ENABLE:
                rc = rmnet_map_do_flow_control(skb, port, 1);
                break;

        case RMNET_MAP_COMMAND_FLOW_DISABLE:
                rc = rmnet_map_do_flow_control(skb, port, 0);
                break;

        default:
                rc = RMNET_MAP_COMMAND_UNSUPPORTED;
                kfree_skb(skb);
                break;
        }
        if (rc == RMNET_MAP_COMMAND_ACK)
                rmnet_map_send_ack(skb, rc, port);
}