/*
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* net/dsa/tag_ksz.c - Microchip KSZ Switch tag format handling
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* Copyright (c) 2017 Microchip Technology
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*/
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#include <linux/etherdevice.h>
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#include <linux/list.h>
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#include <linux/slab.h>
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#include <net/dsa.h>
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#include "dsa_priv.h"
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/* For Ingress (Host -> KSZ), 2 bytes are added before FCS.
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* ---------------------------------------------------------------------------
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* DA(6bytes)|SA(6bytes)|....|Data(nbytes)|tag0(1byte)|tag1(1byte)|FCS(4bytes)
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* ---------------------------------------------------------------------------
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* tag0 : Prioritization (not used now)
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* tag1 : each bit represents port (eg, 0x01=port1, 0x02=port2, 0x10=port5)
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*
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* For Egress (KSZ -> Host), 1 byte is added before FCS.
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* ---------------------------------------------------------------------------
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* DA(6bytes)|SA(6bytes)|....|Data(nbytes)|tag0(1byte)|FCS(4bytes)
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* ---------------------------------------------------------------------------
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* tag0 : zero-based value represents port
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* (eg, 0x00=port1, 0x02=port3, 0x06=port7)
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*/
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#define KSZ_INGRESS_TAG_LEN 2
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#define KSZ_EGRESS_TAG_LEN 1
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static struct sk_buff *ksz_xmit(struct sk_buff *skb, struct net_device *dev)
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{
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struct dsa_port *dp = dsa_slave_to_port(dev);
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struct sk_buff *nskb;
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int padlen;
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u8 *tag;
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padlen = (skb->len >= ETH_ZLEN) ? 0 : ETH_ZLEN - skb->len;
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if (skb_tailroom(skb) >= padlen + KSZ_INGRESS_TAG_LEN) {
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/* Let dsa_slave_xmit() free skb */
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if (__skb_put_padto(skb, skb->len + padlen, false))
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return NULL;
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nskb = skb;
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} else {
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nskb = alloc_skb(NET_IP_ALIGN + skb->len +
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padlen + KSZ_INGRESS_TAG_LEN, GFP_ATOMIC);
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if (!nskb)
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return NULL;
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skb_reserve(nskb, NET_IP_ALIGN);
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skb_reset_mac_header(nskb);
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skb_set_network_header(nskb,
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skb_network_header(skb) - skb->head);
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skb_set_transport_header(nskb,
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skb_transport_header(skb) - skb->head);
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skb_copy_and_csum_dev(skb, skb_put(nskb, skb->len));
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/* Let skb_put_padto() free nskb, and let dsa_slave_xmit() free
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* skb
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*/
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if (skb_put_padto(nskb, nskb->len + padlen))
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return NULL;
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consume_skb(skb);
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}
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tag = skb_put(nskb, KSZ_INGRESS_TAG_LEN);
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tag[0] = 0;
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tag[1] = 1 << dp->index; /* destination port */
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return nskb;
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}
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static struct sk_buff *ksz_rcv(struct sk_buff *skb, struct net_device *dev,
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struct packet_type *pt)
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{
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u8 *tag;
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int source_port;
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tag = skb_tail_pointer(skb) - KSZ_EGRESS_TAG_LEN;
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source_port = tag[0] & 7;
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skb->dev = dsa_master_find_slave(dev, 0, source_port);
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if (!skb->dev)
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return NULL;
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pskb_trim_rcsum(skb, skb->len - KSZ_EGRESS_TAG_LEN);
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return skb;
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}
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const struct dsa_device_ops ksz_netdev_ops = {
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.xmit = ksz_xmit,
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.rcv = ksz_rcv,
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};
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