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![Vladimir Oltean](/assets/img/avatar_default.png)
This is a preparation patch for the tc-taprio offload (and potentially for other future offloads such as tc-mqprio). Instead of looking directly at skb->priority during xmit, let's get the netdev queue and the queue-to-traffic-class mapping, and put the resulting traffic class into the dsa_8021q PCP field. The switch is configured with a 1-to-1 PCP-to-ingress-queue-to-egress-queue mapping (see vlan_pmap in sja1105_main.c), so the effect is that we can inject into a front-panel's egress traffic class through VLAN tagging from Linux, completely transparently. Unfortunately the switch doesn't look at the VLAN PCP in the case of management traffic to/from the CPU (link-local frames at 01-80-C2-xx-xx-xx or 01-1B-19-xx-xx-xx) so we can't alter the transmission queue of this type of traffic on a frame-by-frame basis. It is only selected through the "hostprio" setting which ATM is harcoded in the driver to 7. Signed-off-by: Vladimir Oltean <olteanv@gmail.com> Reviewed-by: Florian Fainelli <f.fainelli@gmail.com> Signed-off-by: David S. Miller <davem@davemloft.net>
298 lines
8.6 KiB
C
298 lines
8.6 KiB
C
// SPDX-License-Identifier: GPL-2.0
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/* Copyright (c) 2019, Vladimir Oltean <olteanv@gmail.com>
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*/
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#include <linux/if_vlan.h>
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#include <linux/dsa/sja1105.h>
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#include <linux/dsa/8021q.h>
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#include <linux/packing.h>
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#include "dsa_priv.h"
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/* Similar to is_link_local_ether_addr(hdr->h_dest) but also covers PTP */
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static inline bool sja1105_is_link_local(const struct sk_buff *skb)
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{
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const struct ethhdr *hdr = eth_hdr(skb);
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u64 dmac = ether_addr_to_u64(hdr->h_dest);
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if (ntohs(hdr->h_proto) == ETH_P_SJA1105_META)
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return false;
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if ((dmac & SJA1105_LINKLOCAL_FILTER_A_MASK) ==
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SJA1105_LINKLOCAL_FILTER_A)
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return true;
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if ((dmac & SJA1105_LINKLOCAL_FILTER_B_MASK) ==
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SJA1105_LINKLOCAL_FILTER_B)
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return true;
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return false;
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}
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struct sja1105_meta {
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u64 tstamp;
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u64 dmac_byte_4;
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u64 dmac_byte_3;
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u64 source_port;
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u64 switch_id;
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};
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static void sja1105_meta_unpack(const struct sk_buff *skb,
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struct sja1105_meta *meta)
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{
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u8 *buf = skb_mac_header(skb) + ETH_HLEN;
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/* UM10944.pdf section 4.2.17 AVB Parameters:
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* Structure of the meta-data follow-up frame.
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* It is in network byte order, so there are no quirks
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* while unpacking the meta frame.
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*
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* Also SJA1105 E/T only populates bits 23:0 of the timestamp
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* whereas P/Q/R/S does 32 bits. Since the structure is the
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* same and the E/T puts zeroes in the high-order byte, use
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* a unified unpacking command for both device series.
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*/
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packing(buf, &meta->tstamp, 31, 0, 4, UNPACK, 0);
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packing(buf + 4, &meta->dmac_byte_4, 7, 0, 1, UNPACK, 0);
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packing(buf + 5, &meta->dmac_byte_3, 7, 0, 1, UNPACK, 0);
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packing(buf + 6, &meta->source_port, 7, 0, 1, UNPACK, 0);
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packing(buf + 7, &meta->switch_id, 7, 0, 1, UNPACK, 0);
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}
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static inline bool sja1105_is_meta_frame(const struct sk_buff *skb)
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{
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const struct ethhdr *hdr = eth_hdr(skb);
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u64 smac = ether_addr_to_u64(hdr->h_source);
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u64 dmac = ether_addr_to_u64(hdr->h_dest);
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if (smac != SJA1105_META_SMAC)
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return false;
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if (dmac != SJA1105_META_DMAC)
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return false;
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if (ntohs(hdr->h_proto) != ETH_P_SJA1105_META)
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return false;
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return true;
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}
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/* This is the first time the tagger sees the frame on RX.
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* Figure out if we can decode it.
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*/
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static bool sja1105_filter(const struct sk_buff *skb, struct net_device *dev)
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{
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if (!dsa_port_is_vlan_filtering(dev->dsa_ptr))
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return true;
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if (sja1105_is_link_local(skb))
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return true;
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if (sja1105_is_meta_frame(skb))
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return true;
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return false;
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}
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static struct sk_buff *sja1105_xmit(struct sk_buff *skb,
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struct net_device *netdev)
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{
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struct dsa_port *dp = dsa_slave_to_port(netdev);
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struct dsa_switch *ds = dp->ds;
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u16 tx_vid = dsa_8021q_tx_vid(ds, dp->index);
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u16 queue_mapping = skb_get_queue_mapping(skb);
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u8 pcp = netdev_txq_to_tc(netdev, queue_mapping);
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/* Transmitting management traffic does not rely upon switch tagging,
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* but instead SPI-installed management routes. Part 2 of this
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* is the .port_deferred_xmit driver callback.
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*/
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if (unlikely(sja1105_is_link_local(skb)))
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return dsa_defer_xmit(skb, netdev);
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/* If we are under a vlan_filtering bridge, IP termination on
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* switch ports based on 802.1Q tags is simply too brittle to
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* be passable. So just defer to the dsa_slave_notag_xmit
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* implementation.
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*/
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if (dsa_port_is_vlan_filtering(dp))
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return skb;
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return dsa_8021q_xmit(skb, netdev, ETH_P_SJA1105,
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((pcp << VLAN_PRIO_SHIFT) | tx_vid));
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}
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static void sja1105_transfer_meta(struct sk_buff *skb,
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const struct sja1105_meta *meta)
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{
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struct ethhdr *hdr = eth_hdr(skb);
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hdr->h_dest[3] = meta->dmac_byte_3;
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hdr->h_dest[4] = meta->dmac_byte_4;
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SJA1105_SKB_CB(skb)->meta_tstamp = meta->tstamp;
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}
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/* This is a simple state machine which follows the hardware mechanism of
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* generating RX timestamps:
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*
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* After each timestampable skb (all traffic for which send_meta1 and
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* send_meta0 is true, aka all MAC-filtered link-local traffic) a meta frame
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* containing a partial timestamp is immediately generated by the switch and
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* sent as a follow-up to the link-local frame on the CPU port.
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*
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* The meta frames have no unique identifier (such as sequence number) by which
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* one may pair them to the correct timestampable frame.
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* Instead, the switch has internal logic that ensures no frames are sent on
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* the CPU port between a link-local timestampable frame and its corresponding
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* meta follow-up. It also ensures strict ordering between ports (lower ports
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* have higher priority towards the CPU port). For this reason, a per-port
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* data structure is not needed/desirable.
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*
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* This function pairs the link-local frame with its partial timestamp from the
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* meta follow-up frame. The full timestamp will be reconstructed later in a
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* work queue.
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*/
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static struct sk_buff
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*sja1105_rcv_meta_state_machine(struct sk_buff *skb,
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struct sja1105_meta *meta,
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bool is_link_local,
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bool is_meta)
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{
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struct sja1105_port *sp;
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struct dsa_port *dp;
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dp = dsa_slave_to_port(skb->dev);
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sp = dp->priv;
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/* Step 1: A timestampable frame was received.
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* Buffer it until we get its meta frame.
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*/
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if (is_link_local && sp->data->hwts_rx_en) {
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spin_lock(&sp->data->meta_lock);
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/* Was this a link-local frame instead of the meta
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* that we were expecting?
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*/
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if (sp->data->stampable_skb) {
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dev_err_ratelimited(dp->ds->dev,
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"Expected meta frame, is %12llx "
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"in the DSA master multicast filter?\n",
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SJA1105_META_DMAC);
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kfree_skb(sp->data->stampable_skb);
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}
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/* Hold a reference to avoid dsa_switch_rcv
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* from freeing the skb.
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*/
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sp->data->stampable_skb = skb_get(skb);
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spin_unlock(&sp->data->meta_lock);
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/* Tell DSA we got nothing */
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return NULL;
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/* Step 2: The meta frame arrived.
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* Time to take the stampable skb out of the closet, annotate it
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* with the partial timestamp, and pretend that we received it
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* just now (basically masquerade the buffered frame as the meta
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* frame, which serves no further purpose).
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*/
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} else if (is_meta) {
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struct sk_buff *stampable_skb;
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spin_lock(&sp->data->meta_lock);
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stampable_skb = sp->data->stampable_skb;
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sp->data->stampable_skb = NULL;
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/* Was this a meta frame instead of the link-local
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* that we were expecting?
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*/
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if (!stampable_skb) {
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dev_err_ratelimited(dp->ds->dev,
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"Unexpected meta frame\n");
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spin_unlock(&sp->data->meta_lock);
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return NULL;
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}
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if (stampable_skb->dev != skb->dev) {
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dev_err_ratelimited(dp->ds->dev,
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"Meta frame on wrong port\n");
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spin_unlock(&sp->data->meta_lock);
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return NULL;
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}
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/* Free the meta frame and give DSA the buffered stampable_skb
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* for further processing up the network stack.
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*/
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kfree_skb(skb);
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skb = stampable_skb;
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sja1105_transfer_meta(skb, meta);
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spin_unlock(&sp->data->meta_lock);
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}
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return skb;
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}
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static struct sk_buff *sja1105_rcv(struct sk_buff *skb,
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struct net_device *netdev,
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struct packet_type *pt)
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{
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struct sja1105_meta meta = {0};
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int source_port, switch_id;
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struct vlan_ethhdr *hdr;
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u16 tpid, vid, tci;
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bool is_link_local;
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bool is_tagged;
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bool is_meta;
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hdr = vlan_eth_hdr(skb);
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tpid = ntohs(hdr->h_vlan_proto);
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is_tagged = (tpid == ETH_P_SJA1105);
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is_link_local = sja1105_is_link_local(skb);
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is_meta = sja1105_is_meta_frame(skb);
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skb->offload_fwd_mark = 1;
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if (is_tagged) {
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/* Normal traffic path. */
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tci = ntohs(hdr->h_vlan_TCI);
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vid = tci & VLAN_VID_MASK;
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source_port = dsa_8021q_rx_source_port(vid);
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switch_id = dsa_8021q_rx_switch_id(vid);
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skb->priority = (tci & VLAN_PRIO_MASK) >> VLAN_PRIO_SHIFT;
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} else if (is_link_local) {
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/* Management traffic path. Switch embeds the switch ID and
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* port ID into bytes of the destination MAC, courtesy of
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* the incl_srcpt options.
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*/
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source_port = hdr->h_dest[3];
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switch_id = hdr->h_dest[4];
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/* Clear the DMAC bytes that were mangled by the switch */
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hdr->h_dest[3] = 0;
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hdr->h_dest[4] = 0;
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} else if (is_meta) {
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sja1105_meta_unpack(skb, &meta);
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source_port = meta.source_port;
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switch_id = meta.switch_id;
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} else {
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return NULL;
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}
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skb->dev = dsa_master_find_slave(netdev, switch_id, source_port);
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if (!skb->dev) {
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netdev_warn(netdev, "Couldn't decode source port\n");
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return NULL;
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}
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/* Delete/overwrite fake VLAN header, DSA expects to not find
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* it there, see dsa_switch_rcv: skb_push(skb, ETH_HLEN).
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*/
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if (is_tagged)
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skb = dsa_8021q_remove_header(skb);
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return sja1105_rcv_meta_state_machine(skb, &meta, is_link_local,
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is_meta);
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}
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static struct dsa_device_ops sja1105_netdev_ops = {
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.name = "sja1105",
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.proto = DSA_TAG_PROTO_SJA1105,
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.xmit = sja1105_xmit,
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.rcv = sja1105_rcv,
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.filter = sja1105_filter,
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.overhead = VLAN_HLEN,
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};
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MODULE_LICENSE("GPL v2");
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MODULE_ALIAS_DSA_TAG_DRIVER(DSA_TAG_PROTO_SJA1105);
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module_dsa_tag_driver(sja1105_netdev_ops);
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