/* Copyright 2011-2014 Autronica Fire and Security AS
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License as published by the Free
 * Software Foundation; either version 2 of the License, or (at your option)
 * any later version.
 *
 * Author(s):
 *      2011-2014 Arvid Brodin, arvid.brodin@alten.se
 *
 * This file contains device methods for creating, using and destroying
 * virtual HSR devices.
 */

#include <linux/netdevice.h>
#include <linux/skbuff.h>
#include <linux/etherdevice.h>
#include <linux/rtnetlink.h>
#include <linux/pkt_sched.h>
#include "hsr_device.h"
#include "hsr_slave.h"
#include "hsr_framereg.h"
#include "hsr_main.h"
#include "hsr_forward.h"


static bool is_admin_up(struct net_device *dev)
{
        return dev && (dev->flags & IFF_UP);
}

static bool is_slave_up(struct net_device *dev)
{
        return dev && is_admin_up(dev) && netif_oper_up(dev);
}

static void __hsr_set_operstate(struct net_device *dev, int transition)
{
        write_lock_bh(&dev_base_lock);
        if (dev->operstate != transition) {
                dev->operstate = transition;
                write_unlock_bh(&dev_base_lock);
                netdev_state_change(dev);
        } else {
                write_unlock_bh(&dev_base_lock);
        }
}

static void hsr_set_operstate(struct hsr_port *master, bool has_carrier)
{
        if (!is_admin_up(master->dev)) {
                __hsr_set_operstate(master->dev, IF_OPER_DOWN);
                return;
        }

        if (has_carrier)
                __hsr_set_operstate(master->dev, IF_OPER_UP);
        else
                __hsr_set_operstate(master->dev, IF_OPER_LOWERLAYERDOWN);
}

static bool hsr_check_carrier(struct hsr_port *master)
{
        struct hsr_port *port;
        bool has_carrier;

        has_carrier = false;

        rcu_read_lock();
        hsr_for_each_port(master->hsr, port)
                if ((port->type != HSR_PT_MASTER) && is_slave_up(port->dev)) {
                        has_carrier = true;
                        break;
                }
        rcu_read_unlock();

        if (has_carrier)
                netif_carrier_on(master->dev);
        else
                netif_carrier_off(master->dev);

        return has_carrier;
}


static void hsr_check_announce(struct net_device *hsr_dev,
                               unsigned char old_operstate)
{
        struct hsr_priv *hsr;

        hsr = netdev_priv(hsr_dev);

        if ((hsr_dev->operstate == IF_OPER_UP) && (old_operstate != IF_OPER_UP)) {
                /* Went up */
                hsr->announce_count = 0;
                hsr->announce_timer.expires = jiffies +
                                msecs_to_jiffies(HSR_ANNOUNCE_INTERVAL);
                add_timer(&hsr->announce_timer);
        }

        if ((hsr_dev->operstate != IF_OPER_UP) && (old_operstate == IF_OPER_UP))
                /* Went down */
                del_timer(&hsr->announce_timer);
}

void hsr_check_carrier_and_operstate(struct hsr_priv *hsr)
{
        struct hsr_port *master;
        unsigned char old_operstate;
        bool has_carrier;

        master = hsr_port_get_hsr(hsr, HSR_PT_MASTER);
        /* netif_stacked_transfer_operstate() cannot be used here since
         * it doesn't set IF_OPER_LOWERLAYERDOWN (?)
         */
        old_operstate = master->dev->operstate;
        has_carrier = hsr_check_carrier(master);
        hsr_set_operstate(master, has_carrier);
        hsr_check_announce(master->dev, old_operstate);
}

int hsr_get_max_mtu(struct hsr_priv *hsr)
{
        unsigned int mtu_max;
        struct hsr_port *port;

        mtu_max = ETH_DATA_LEN;
        rcu_read_lock();
        hsr_for_each_port(hsr, port)
                if (port->type != HSR_PT_MASTER)
                        mtu_max = min(port->dev->mtu, mtu_max);
        rcu_read_unlock();

        if (mtu_max < HSR_HLEN)
                return 0;
        return mtu_max - HSR_HLEN;
}


static int hsr_dev_change_mtu(struct net_device *dev, int new_mtu)
{
        struct hsr_priv *hsr;
        struct hsr_port *master;

        hsr = netdev_priv(dev);
        master = hsr_port_get_hsr(hsr, HSR_PT_MASTER);

        if (new_mtu > hsr_get_max_mtu(hsr)) {
                netdev_info(master->dev, "A HSR master's MTU cannot be greater than the smallest MTU of its slaves minus the HSR Tag length (%d octets).\n",
                            HSR_HLEN);
                return -EINVAL;
        }

        dev->mtu = new_mtu;

        return 0;
}

static int hsr_dev_open(struct net_device *dev)
{
        struct hsr_priv *hsr;
        struct hsr_port *port;
        char designation;

        hsr = netdev_priv(dev);
        designation = '\0';

        rcu_read_lock();
        hsr_for_each_port(hsr, port) {
                if (port->type == HSR_PT_MASTER)
                        continue;
                switch (port->type) {
                case HSR_PT_SLAVE_A:
                        designation = 'A';
                        break;
                case HSR_PT_SLAVE_B:
                        designation = 'B';
                        break;
                default:
                        designation = '?';
                }
                if (!is_slave_up(port->dev))
                        netdev_warn(dev, "Slave %c (%s) is not up; please bring it up to get a fully working HSR network\n",
                                    designation, port->dev->name);
        }
        rcu_read_unlock();

        if (designation == '\0')
                netdev_warn(dev, "No slave devices configured\n");

        return 0;
}


static int hsr_dev_close(struct net_device *dev)
{
        /* Nothing to do here. */
        return 0;
}


static netdev_features_t hsr_features_recompute(struct hsr_priv *hsr,
                                                netdev_features_t features)
{
        netdev_features_t mask;
        struct hsr_port *port;

        mask = features;

        /* Mask out all features that, if supported by one device, should be
         * enabled for all devices (see NETIF_F_ONE_FOR_ALL).
         *
         * Anything that's off in mask will not be enabled - so only things
         * that were in features originally, and also is in NETIF_F_ONE_FOR_ALL,
         * may become enabled.
         */
        features &= ~NETIF_F_ONE_FOR_ALL;
        hsr_for_each_port(hsr, port)
                features = netdev_increment_features(features,
                                                     port->dev->features,
                                                     mask);

        return features;
}

static netdev_features_t hsr_fix_features(struct net_device *dev,
                                          netdev_features_t features)
{
        struct hsr_priv *hsr = netdev_priv(dev);

        return hsr_features_recompute(hsr, features);
}


static int hsr_dev_xmit(struct sk_buff *skb, struct net_device *dev)
{
        struct hsr_priv *hsr = netdev_priv(dev);
        struct hsr_port *master;

        master = hsr_port_get_hsr(hsr, HSR_PT_MASTER);
        skb->dev = master->dev;
        hsr_forward_skb(skb, master);

        return NETDEV_TX_OK;
}


static const struct header_ops hsr_header_ops = {
        .create  = eth_header,
        .parse   = eth_header_parse,
};


/* HSR:2010 supervision frames should be padded so that the whole frame,
 * including headers and FCS, is 64 bytes (without VLAN).
 */
static int hsr_pad(int size)
{
        const int min_size = ETH_ZLEN - HSR_HLEN - ETH_HLEN;

        if (size >= min_size)
                return size;
        return min_size;
}

static void send_hsr_supervision_frame(struct hsr_port *master, u8 type)
{
        struct sk_buff *skb;
        int hlen, tlen;
        struct hsr_sup_tag *hsr_stag;
        struct hsr_sup_payload *hsr_sp;
        unsigned long irqflags;

        hlen = LL_RESERVED_SPACE(master->dev);
        tlen = master->dev->needed_tailroom;
        skb = alloc_skb(hsr_pad(sizeof(struct hsr_sup_payload)) + hlen + tlen,
                        GFP_ATOMIC);

        if (skb == NULL)
                return;

        skb_reserve(skb, hlen);

        skb->dev = master->dev;
        skb->protocol = htons(ETH_P_PRP);
        skb->priority = TC_PRIO_CONTROL;

        if (dev_hard_header(skb, skb->dev, ETH_P_PRP,
                            master->hsr->sup_multicast_addr,
                            skb->dev->dev_addr, skb->len) <= 0)
                goto out;
        skb_reset_mac_header(skb);

        hsr_stag = (typeof(hsr_stag)) skb_put(skb, sizeof(*hsr_stag));

        set_hsr_stag_path(hsr_stag, 0xf);
        set_hsr_stag_HSR_Ver(hsr_stag, 0);

        spin_lock_irqsave(&master->hsr->seqnr_lock, irqflags);
        hsr_stag->sequence_nr = htons(master->hsr->sequence_nr);
        master->hsr->sequence_nr++;
        spin_unlock_irqrestore(&master->hsr->seqnr_lock, irqflags);

        hsr_stag->HSR_TLV_Type = type;
        hsr_stag->HSR_TLV_Length = 12;

        /* Payload: MacAddressA */
        hsr_sp = (typeof(hsr_sp)) skb_put(skb, sizeof(*hsr_sp));
        ether_addr_copy(hsr_sp->MacAddressA, master->dev->dev_addr);

        hsr_forward_skb(skb, master);
        return;

out:
        WARN_ONCE(1, "HSR: Could not send supervision frame\n");
        kfree_skb(skb);
}


/* Announce (supervision frame) timer function
 */
static void hsr_announce(unsigned long data)
{
        struct hsr_priv *hsr;
        struct hsr_port *master;

        hsr = (struct hsr_priv *) data;

        rcu_read_lock();
        master = hsr_port_get_hsr(hsr, HSR_PT_MASTER);

        if (hsr->announce_count < 3) {
                send_hsr_supervision_frame(master, HSR_TLV_ANNOUNCE);
                hsr->announce_count++;
        } else {
                send_hsr_supervision_frame(master, HSR_TLV_LIFE_CHECK);
        }

        if (hsr->announce_count < 3)
                hsr->announce_timer.expires = jiffies +
                                msecs_to_jiffies(HSR_ANNOUNCE_INTERVAL);
        else
                hsr->announce_timer.expires = jiffies +
                                msecs_to_jiffies(HSR_LIFE_CHECK_INTERVAL);

        if (is_admin_up(master->dev))
                add_timer(&hsr->announce_timer);

        rcu_read_unlock();
}


/* According to comments in the declaration of struct net_device, this function
 * is "Called from unregister, can be used to call free_netdev". Ok then...
 */
static void hsr_dev_destroy(struct net_device *hsr_dev)
{
        struct hsr_priv *hsr;
        struct hsr_port *port;

        hsr = netdev_priv(hsr_dev);

        rtnl_lock();
        hsr_for_each_port(hsr, port)
                hsr_del_port(port);
        rtnl_unlock();

        del_timer_sync(&hsr->prune_timer);
        del_timer_sync(&hsr->announce_timer);

        synchronize_rcu();
        free_netdev(hsr_dev);
}

static const struct net_device_ops hsr_device_ops = {
        .ndo_change_mtu = hsr_dev_change_mtu,
        .ndo_open = hsr_dev_open,
        .ndo_stop = hsr_dev_close,
        .ndo_start_xmit = hsr_dev_xmit,
        .ndo_fix_features = hsr_fix_features,
};

static struct device_type hsr_type = {
        .name = "hsr",
};

void hsr_dev_setup(struct net_device *dev)
{
        random_ether_addr(dev->dev_addr);

        ether_setup(dev);
        dev->header_ops = &hsr_header_ops;
        dev->netdev_ops = &hsr_device_ops;
        SET_NETDEV_DEVTYPE(dev, &hsr_type);
        dev->priv_flags |= IFF_NO_QUEUE;

        dev->destructor = hsr_dev_destroy;

        dev->hw_features = NETIF_F_SG | NETIF_F_FRAGLIST | NETIF_F_HIGHDMA |
                           NETIF_F_GSO_MASK | NETIF_F_HW_CSUM |
                           NETIF_F_HW_VLAN_CTAG_TX;

        dev->features = dev->hw_features;

        /* Prevent recursive tx locking */
        dev->features |= NETIF_F_LLTX;
        /* VLAN on top of HSR needs testing and probably some work on
         * hsr_header_create() etc.
         */
        dev->features |= NETIF_F_VLAN_CHALLENGED;
        /* Not sure about this. Taken from bridge code. netdev_features.h says
         * it means "Does not change network namespaces".
         */
        dev->features |= NETIF_F_NETNS_LOCAL;
}


/* Return true if dev is a HSR master; return false otherwise.
 */
inline bool is_hsr_master(struct net_device *dev)
{
        return (dev->netdev_ops->ndo_start_xmit == hsr_dev_xmit);
}

/* Default multicast address for HSR Supervision frames */
static const unsigned char def_multicast_addr[ETH_ALEN] __aligned(2) = {
        0x01, 0x15, 0x4e, 0x00, 0x01, 0x00
};

int hsr_dev_finalize(struct net_device *hsr_dev, struct net_device *slave[2],
                     unsigned char multicast_spec)
{
        struct hsr_priv *hsr;
        struct hsr_port *port;
        int res;

        hsr = netdev_priv(hsr_dev);
        INIT_LIST_HEAD(&hsr->ports);
        INIT_LIST_HEAD(&hsr->node_db);
        INIT_LIST_HEAD(&hsr->self_node_db);

        ether_addr_copy(hsr_dev->dev_addr, slave[0]->dev_addr);

        /* Make sure we recognize frames from ourselves in hsr_rcv() */
        res = hsr_create_self_node(&hsr->self_node_db, hsr_dev->dev_addr,
                                   slave[1]->dev_addr);
        if (res < 0)
                return res;

        spin_lock_init(&hsr->seqnr_lock);
        /* Overflow soon to find bugs easier: */
        hsr->sequence_nr = HSR_SEQNR_START;

        init_timer(&hsr->announce_timer);
        hsr->announce_timer.function = hsr_announce;
        hsr->announce_timer.data = (unsigned long) hsr;

        init_timer(&hsr->prune_timer);
        hsr->prune_timer.function = hsr_prune_nodes;
        hsr->prune_timer.data = (unsigned long) hsr;

        ether_addr_copy(hsr->sup_multicast_addr, def_multicast_addr);
        hsr->sup_multicast_addr[ETH_ALEN - 1] = multicast_spec;

        /* FIXME: should I modify the value of these?
         *
         * - hsr_dev->flags - i.e.
         *                      IFF_MASTER/SLAVE?
         * - hsr_dev->priv_flags - i.e.
         *                      IFF_EBRIDGE?
         *                      IFF_TX_SKB_SHARING?
         *                      IFF_HSR_MASTER/SLAVE?
         */

        /* Make sure the 1st call to netif_carrier_on() gets through */
        netif_carrier_off(hsr_dev);

        res = hsr_add_port(hsr, hsr_dev, HSR_PT_MASTER);
        if (res)
                return res;

        res = register_netdevice(hsr_dev);
        if (res)
                goto fail;

        res = hsr_add_port(hsr, slave[0], HSR_PT_SLAVE_A);
        if (res)
                goto fail;
        res = hsr_add_port(hsr, slave[1], HSR_PT_SLAVE_B);
        if (res)
                goto fail;

        hsr->prune_timer.expires = jiffies + msecs_to_jiffies(PRUNE_PERIOD);
        add_timer(&hsr->prune_timer);

        return 0;

fail:
        hsr_for_each_port(hsr, port)
                hsr_del_port(port);

        return res;
}