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

#include <linux/etherdevice.h>
#include <linux/if_arp.h>
#include <linux/if_link.h>
#include <linux/rtnetlink.h>
#include <linux/wwan.h>
#include <net/pkt_sched.h>

#include "iosm_ipc_chnl_cfg.h"
#include "iosm_ipc_imem_ops.h"
#include "iosm_ipc_wwan.h"

#define IOSM_IP_TYPE_MASK 0xF0
#define IOSM_IP_TYPE_IPV4 0x40
#define IOSM_IP_TYPE_IPV6 0x60

/**
 * struct iosm_netdev_priv - netdev WWAN driver specific private data
 * @ipc_wwan:   Pointer to iosm_wwan struct
 * @netdev:     Pointer to network interface device structure
 * @if_id:      Interface id for device.
 * @ch_id:      IPC channel number for which interface device is created.
 */
struct iosm_netdev_priv {
        struct iosm_wwan *ipc_wwan;
        struct net_device *netdev;
        int if_id;
        int ch_id;
};

/**
 * struct iosm_wwan - This structure contains information about WWAN root device
 *                    and interface to the IPC layer.
 * @ipc_imem:           Pointer to imem data-struct
 * @sub_netlist:        List of active netdevs
 * @dev:                Pointer device structure
 */
struct iosm_wwan {
        struct iosm_imem *ipc_imem;
        struct iosm_netdev_priv __rcu *sub_netlist[IP_MUX_SESSION_END + 1];
        struct device *dev;
};

/* Bring-up the wwan net link */
static int ipc_wwan_link_open(struct net_device *netdev)
{
        struct iosm_netdev_priv *priv = wwan_netdev_drvpriv(netdev);
        struct iosm_wwan *ipc_wwan = priv->ipc_wwan;
        int if_id = priv->if_id;

        if (if_id < IP_MUX_SESSION_START ||
            if_id >= ARRAY_SIZE(ipc_wwan->sub_netlist))
                return -EINVAL;

        /* get channel id */
        priv->ch_id = ipc_imem_sys_wwan_open(ipc_wwan->ipc_imem, if_id);

        if (priv->ch_id < 0) {
                dev_err(ipc_wwan->dev,
                        "cannot connect wwan0 & id %d to the IPC mem layer",
                        if_id);
                return -ENODEV;
        }

        /* enable tx path, DL data may follow */
        netif_start_queue(netdev);

        dev_dbg(ipc_wwan->dev, "Channel id %d allocated to if_id %d",
                priv->ch_id, priv->if_id);

        return 0;
}

/* Bring-down the wwan net link */
static int ipc_wwan_link_stop(struct net_device *netdev)
{
        struct iosm_netdev_priv *priv = wwan_netdev_drvpriv(netdev);

        netif_stop_queue(netdev);

        ipc_imem_sys_wwan_close(priv->ipc_wwan->ipc_imem, priv->if_id,
                                priv->ch_id);
        priv->ch_id = -1;

        return 0;
}

/* Transmit a packet */
static netdev_tx_t ipc_wwan_link_transmit(struct sk_buff *skb,
                                          struct net_device *netdev)
{
        struct iosm_netdev_priv *priv = wwan_netdev_drvpriv(netdev);
        struct iosm_wwan *ipc_wwan = priv->ipc_wwan;
        unsigned int len = skb->len;
        int if_id = priv->if_id;
        int ret;

        /* Interface IDs from 1 to 8 are for IP data
         * & from 257 to 261 are for non-IP data
         */
        if (if_id < IP_MUX_SESSION_START ||
            if_id >= ARRAY_SIZE(ipc_wwan->sub_netlist))
                return -EINVAL;

        /* Send the SKB to device for transmission */
        ret = ipc_imem_sys_wwan_transmit(ipc_wwan->ipc_imem,
                                         if_id, priv->ch_id, skb);

        /* Return code of zero is success */
        if (ret == 0) {
                netdev->stats.tx_packets++;
                netdev->stats.tx_bytes += len;
                ret = NETDEV_TX_OK;
        } else if (ret == -EBUSY) {
                ret = NETDEV_TX_BUSY;
                dev_err(ipc_wwan->dev, "unable to push packets");
        } else {
                goto exit;
        }

        return ret;

exit:
        /* Log any skb drop */
        if (if_id)
                dev_dbg(ipc_wwan->dev, "skb dropped. IF_ID: %d, ret: %d", if_id,
                        ret);

        dev_kfree_skb_any(skb);
        netdev->stats.tx_dropped++;
        return NETDEV_TX_OK;
}

/* Ops structure for wwan net link */
static const struct net_device_ops ipc_inm_ops = {
        .ndo_open = ipc_wwan_link_open,
        .ndo_stop = ipc_wwan_link_stop,
        .ndo_start_xmit = ipc_wwan_link_transmit,
};

/* Setup function for creating new net link */
static void ipc_wwan_setup(struct net_device *iosm_dev)
{
        iosm_dev->header_ops = NULL;
        iosm_dev->hard_header_len = 0;
        iosm_dev->tx_queue_len = DEFAULT_TX_QUEUE_LEN;

        iosm_dev->type = ARPHRD_NONE;
        iosm_dev->mtu = ETH_DATA_LEN;
        iosm_dev->min_mtu = ETH_MIN_MTU;
        iosm_dev->max_mtu = ETH_MAX_MTU;

        iosm_dev->flags = IFF_POINTOPOINT | IFF_NOARP;
        iosm_dev->needs_free_netdev = true;

        iosm_dev->netdev_ops = &ipc_inm_ops;
}

/* Create new wwan net link */
static int ipc_wwan_newlink(void *ctxt, struct net_device *dev,
                            u32 if_id, struct netlink_ext_ack *extack)
{
        struct iosm_wwan *ipc_wwan = ctxt;
        struct iosm_netdev_priv *priv;
        int err;

        if (if_id < IP_MUX_SESSION_START ||
            if_id >= ARRAY_SIZE(ipc_wwan->sub_netlist))
                return -EINVAL;

        priv = wwan_netdev_drvpriv(dev);
        priv->if_id = if_id;
        priv->netdev = dev;
        priv->ipc_wwan = ipc_wwan;

        if (rcu_access_pointer(ipc_wwan->sub_netlist[if_id]))
                return -EBUSY;

        err = register_netdevice(dev);
        if (err)
                return err;

        rcu_assign_pointer(ipc_wwan->sub_netlist[if_id], priv);
        netif_device_attach(dev);

        return 0;
}

static void ipc_wwan_dellink(void *ctxt, struct net_device *dev,
                             struct list_head *head)
{
        struct iosm_netdev_priv *priv = wwan_netdev_drvpriv(dev);
        struct iosm_wwan *ipc_wwan = ctxt;
        int if_id = priv->if_id;

        if (WARN_ON(if_id < IP_MUX_SESSION_START ||
                    if_id >= ARRAY_SIZE(ipc_wwan->sub_netlist)))
                return;

        if (WARN_ON(rcu_access_pointer(ipc_wwan->sub_netlist[if_id]) != priv))
                return;

        RCU_INIT_POINTER(ipc_wwan->sub_netlist[if_id], NULL);
        /* unregistering includes synchronize_net() */
        unregister_netdevice_queue(dev, head);
}

static const struct wwan_ops iosm_wwan_ops = {
        .priv_size = sizeof(struct iosm_netdev_priv),
        .setup = ipc_wwan_setup,
        .newlink = ipc_wwan_newlink,
        .dellink = ipc_wwan_dellink,
};

int ipc_wwan_receive(struct iosm_wwan *ipc_wwan, struct sk_buff *skb_arg,
                     bool dss, int if_id)
{
        struct sk_buff *skb = skb_arg;
        struct net_device_stats *stats;
        struct iosm_netdev_priv *priv;
        int ret;

        if ((skb->data[0] & IOSM_IP_TYPE_MASK) == IOSM_IP_TYPE_IPV4)
                skb->protocol = htons(ETH_P_IP);
        else if ((skb->data[0] & IOSM_IP_TYPE_MASK) ==
                 IOSM_IP_TYPE_IPV6)
                skb->protocol = htons(ETH_P_IPV6);

        skb->pkt_type = PACKET_HOST;

        if (if_id < IP_MUX_SESSION_START ||
            if_id > IP_MUX_SESSION_END) {
                ret = -EINVAL;
                goto free;
        }

        rcu_read_lock();
        priv = rcu_dereference(ipc_wwan->sub_netlist[if_id]);
        if (!priv) {
                ret = -EINVAL;
                goto unlock;
        }
        skb->dev = priv->netdev;
        stats = &priv->netdev->stats;
        stats->rx_packets++;
        stats->rx_bytes += skb->len;

        ret = netif_rx(skb);
        skb = NULL;
unlock:
        rcu_read_unlock();
free:
        dev_kfree_skb(skb);
        return ret;
}

void ipc_wwan_tx_flowctrl(struct iosm_wwan *ipc_wwan, int if_id, bool on)
{
        struct net_device *netdev;
        struct iosm_netdev_priv *priv;
        bool is_tx_blk;

        rcu_read_lock();
        priv = rcu_dereference(ipc_wwan->sub_netlist[if_id]);
        if (!priv) {
                rcu_read_unlock();
                return;
        }

        netdev = priv->netdev;

        is_tx_blk = netif_queue_stopped(netdev);

        if (on)
                dev_dbg(ipc_wwan->dev, "session id[%d]: flowctrl enable",
                        if_id);

        if (on && !is_tx_blk)
                netif_stop_queue(netdev);
        else if (!on && is_tx_blk)
                netif_wake_queue(netdev);
        rcu_read_unlock();
}

struct iosm_wwan *ipc_wwan_init(struct iosm_imem *ipc_imem, struct device *dev)
{
        struct iosm_wwan *ipc_wwan;

        ipc_wwan = kzalloc_obj(*ipc_wwan);
        if (!ipc_wwan)
                return NULL;

        ipc_wwan->dev = dev;
        ipc_wwan->ipc_imem = ipc_imem;

        /* WWAN core will create a netdev for the default IP MUX channel */
        if (wwan_register_ops(ipc_wwan->dev, &iosm_wwan_ops, ipc_wwan,
                              IP_MUX_SESSION_DEFAULT)) {
                kfree(ipc_wwan);
                return NULL;
        }

        return ipc_wwan;
}

void ipc_wwan_deinit(struct iosm_wwan *ipc_wwan)
{
        /* This call will remove all child netdev(s) */
        wwan_unregister_ops(ipc_wwan->dev);

        kfree(ipc_wwan);
}