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authorVladimir Oltean <vladimir.oltean@nxp.com>2021-06-11 22:01:31 +0300
committerDavid S. Miller <davem@davemloft.net>2021-06-11 22:45:38 +0300
commit566b18c8b752f67c4e82f0eb4563dd71f84a8799 (patch)
treedf88850d3135345ad762c298afa385b9b88eb198 /net/dsa
parent30b73242e679fb6cdee9f00aac6e05278fef48ca (diff)
downloadlinux-566b18c8b752f67c4e82f0eb4563dd71f84a8799.tar.xz
net: dsa: sja1105: implement TX timestamping for SJA1110
The TX timestamping procedure for SJA1105 is a bit unconventional because the transmit procedure itself is unconventional. Control packets (and therefore PTP as well) are transmitted to a specific port in SJA1105 using "management routes" which must be written over SPI to the switch. These are one-shot rules that match by destination MAC address on traffic coming from the CPU port, and select the precise destination port for that packet. So to transmit a packet from NET_TX softirq context, we actually need to defer to a process context so that we can perform that SPI write before we send the packet. The DSA master dev_queue_xmit() runs in process context, and we poll until the switch confirms it took the TX timestamp, then we annotate the skb clone with that TX timestamp. This is why the sja1105 driver does not need an skb queue for TX timestamping. But the SJA1110 is a bit (not much!) more conventional, and you can request 2-step TX timestamping through the DSA header, as well as give the switch a cookie (timestamp ID) which it will give back to you when it has the timestamp. So now we do need a queue for keeping the skb clones until their TX timestamps become available. The interesting part is that the metadata frames from SJA1105 haven't disappeared completely. On SJA1105 they were used as follow-ups which contained RX timestamps, but on SJA1110 they are actually TX completion packets, which contain a variable (up to 32) array of timestamps. Why an array? Because: - not only is the TX timestamp on the egress port being communicated, but also the RX timestamp on the CPU port. Nice, but we don't care about that, so we ignore it. - because a packet could be multicast to multiple egress ports, each port takes its own timestamp, and the TX completion packet contains the individual timestamps on each port. This is unconventional because switches typically have a timestamping FIFO and raise an interrupt, but this one doesn't. So the tagger needs to detect and parse meta frames, and call into the main switch driver, which pairs the timestamps with the skbs in the TX timestamping queue which are waiting for one. Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/dsa')
-rw-r--r--net/dsa/tag_sja1105.c52
1 files changed, 52 insertions, 0 deletions
diff --git a/net/dsa/tag_sja1105.c b/net/dsa/tag_sja1105.c
index 37e1d64e07c6..9c2df9ece01b 100644
--- a/net/dsa/tag_sja1105.c
+++ b/net/dsa/tag_sja1105.c
@@ -25,6 +25,9 @@
#define SJA1110_RX_TRAILER_SWITCH_ID(x) (((x) & GENMASK(7, 4)) >> 4)
#define SJA1110_RX_TRAILER_SRC_PORT(x) ((x) & GENMASK(3, 0))
+/* Meta frame format (for 2-step TX timestamps) */
+#define SJA1110_RX_HEADER_N_TS(x) (((x) & GENMASK(8, 4)) >> 4)
+
/* TX header */
#define SJA1110_TX_HEADER_UPDATE_TC BIT(14)
#define SJA1110_TX_HEADER_TAKE_TS BIT(13)
@@ -43,6 +46,8 @@
#define SJA1110_TX_TRAILER_SWITCHID(x) (((x) << 12) & GENMASK(15, 12))
#define SJA1110_TX_TRAILER_DESTPORTS(x) (((x) << 1) & GENMASK(11, 1))
+#define SJA1110_META_TSTAMP_SIZE 10
+
#define SJA1110_HEADER_LEN 4
#define SJA1110_RX_TRAILER_LEN 13
#define SJA1110_TX_TRAILER_LEN 4
@@ -184,6 +189,7 @@ static struct sk_buff *sja1105_xmit(struct sk_buff *skb,
static struct sk_buff *sja1110_xmit(struct sk_buff *skb,
struct net_device *netdev)
{
+ struct sk_buff *clone = SJA1105_SKB_CB(skb)->clone;
struct dsa_port *dp = dsa_slave_to_port(netdev);
u16 tx_vid = dsa_8021q_tx_vid(dp->ds, dp->index);
u16 queue_mapping = skb_get_queue_mapping(skb);
@@ -221,6 +227,12 @@ static struct sk_buff *sja1110_xmit(struct sk_buff *skb,
*tx_trailer = cpu_to_be32(SJA1110_TX_TRAILER_PRIO(pcp) |
SJA1110_TX_TRAILER_SWITCHID(dp->ds->index) |
SJA1110_TX_TRAILER_DESTPORTS(BIT(dp->index)));
+ if (clone) {
+ u8 ts_id = SJA1105_SKB_CB(clone)->ts_id;
+
+ *tx_header |= htons(SJA1110_TX_HEADER_TAKE_TS);
+ *tx_trailer |= cpu_to_be32(SJA1110_TX_TRAILER_TSTAMP_ID(ts_id));
+ }
return skb;
}
@@ -423,6 +435,43 @@ static struct sk_buff *sja1105_rcv(struct sk_buff *skb,
is_meta);
}
+static struct sk_buff *sja1110_rcv_meta(struct sk_buff *skb, u16 rx_header)
+{
+ int switch_id = SJA1110_RX_HEADER_SWITCH_ID(rx_header);
+ int n_ts = SJA1110_RX_HEADER_N_TS(rx_header);
+ struct net_device *master = skb->dev;
+ struct dsa_port *cpu_dp;
+ u8 *buf = skb->data + 2;
+ struct dsa_switch *ds;
+ int i;
+
+ cpu_dp = master->dsa_ptr;
+ ds = dsa_switch_find(cpu_dp->dst->index, switch_id);
+ if (!ds) {
+ net_err_ratelimited("%s: cannot find switch id %d\n",
+ master->name, switch_id);
+ return NULL;
+ }
+
+ for (i = 0; i <= n_ts; i++) {
+ u8 ts_id, source_port, dir;
+ u64 tstamp;
+
+ ts_id = buf[0];
+ source_port = (buf[1] & GENMASK(7, 4)) >> 4;
+ dir = (buf[1] & BIT(3)) >> 3;
+ tstamp = be64_to_cpu(*(__be64 *)(buf + 2));
+
+ sja1110_process_meta_tstamp(ds, source_port, ts_id, dir,
+ tstamp);
+
+ buf += SJA1110_META_TSTAMP_SIZE;
+ }
+
+ /* Discard the meta frame, we've consumed the timestamps it contained */
+ return NULL;
+}
+
static struct sk_buff *sja1110_rcv_inband_control_extension(struct sk_buff *skb,
int *source_port,
int *switch_id)
@@ -439,6 +488,9 @@ static struct sk_buff *sja1110_rcv_inband_control_extension(struct sk_buff *skb,
*/
rx_header = ntohs(*(__be16 *)skb->data);
+ if (rx_header & SJA1110_RX_HEADER_IS_METADATA)
+ return sja1110_rcv_meta(skb, rx_header);
+
/* Timestamp frame, we have a trailer */
if (rx_header & SJA1110_RX_HEADER_HAS_TRAILER) {
int start_of_padding = SJA1110_RX_HEADER_TRAILER_POS(rx_header);