[PATCH net-next 3/5] net: ipqess: Add out-of-band DSA tagging support

[Maxime Chevallier <maxime.chevallier@bootlin.com>]

On the IPQ4019, there's an 5 ports switch connected to the CPU through
the IPQESS Ethernet controller. The way the DSA tag is sent-out to that
switch is through the DMA descriptor, due to how tightly it is
integrated with the switch.

This commit uses the out-of-band tagging protocol to get the outgoing
port index for each SKB, and reports it back in the skb->shinfo on the
RX side based on information located in the descriptor.

Signed-off-by: Maxime Chevallier <maxime.chevallier@bootlin.com>
---
 drivers/net/ethernet/qualcomm/ipqess/ipqess.c | 23 +++++++++++++++++++
 1 file changed, 23 insertions(+)

diff --git a/drivers/net/ethernet/qualcomm/ipqess/ipqess.c b/drivers/net/ethernet/qualcomm/ipqess/ipqess.c
index 4ecb8c65417b..32a5cdd1c063 100644
--- a/drivers/net/ethernet/qualcomm/ipqess/ipqess.c
+++ b/drivers/net/ethernet/qualcomm/ipqess/ipqess.c
@@ -20,6 +20,7 @@
 #include <linux/skbuff.h>
 #include <linux/vmalloc.h>
 #include <net/checksum.h>
+#include <net/dsa.h>
 #include <net/ip6_checksum.h>
 
 #include "ipqess.h"
@@ -399,6 +400,11 @@ static int ipqess_rx_poll(struct ipqess_rx_ring *rx_ring, int budget)
 		skb->protocol = eth_type_trans(skb, rx_ring->ess->netdev);
 		skb_record_rx_queue(skb, rx_ring->ring_id);
 
+		if (netdev_uses_dsa(rx_ring->ess->netdev)) {
+			skb_shinfo(skb)->dsa_tag_info.dp =
+				FIELD_GET(IPQESS_RRD_PORT_ID_MASK, rd->rrd1);
+		}
+
 		if (rd->rrd6 & IPQESS_RRD_CSUM_FAIL_MASK)
 			skb_checksum_none_assert(skb);
 		else
@@ -706,6 +712,21 @@ static void ipqess_rollback_tx(struct ipqess *eth,
 	tx_ring->head = start_index;
 }
 
+static void ipqess_process_dsa_tag_sh(struct ipqess *ess, struct sk_buff *skb,
+				      u32 *word3)
+{
+	struct skb_shared_info *shinfo = skb_shinfo(skb);
+	struct dsa_tag_info *tag_info = &shinfo->dsa_tag_info;
+
+	if (!netdev_uses_dsa(ess->netdev) ||
+	    tag_info->proto != DSA_TAG_PROTO_OOB)
+		return;
+
+	*word3 |= tag_info->dp << IPQESS_TPD_PORT_BITMAP_SHIFT;
+	*word3 |= BIT(IPQESS_TPD_FROM_CPU_SHIFT);
+	*word3 |= 0x3e << IPQESS_TPD_PORT_BITMAP_SHIFT;
+}
+
 static int ipqess_tx_map_and_fill(struct ipqess_tx_ring *tx_ring,
 				  struct sk_buff *skb)
 {
@@ -716,6 +737,8 @@ static int ipqess_tx_map_and_fill(struct ipqess_tx_ring *tx_ring,
 	u16 len;
 	int i;
 
+	ipqess_process_dsa_tag_sh(tx_ring->ess, skb, &word3);
+
 	if (skb_is_gso(skb)) {
 		if (skb_shinfo(skb)->gso_type & SKB_GSO_TCPV4) {
 			lso_word1 |= IPQESS_TPD_IPV4_EN;
-- 
2.35.1