[RFC net-next] net: loopback: Extend netdev features with new loopback modes

[Hariprasad Kelam <hkelam@marvell.com>]

This patch enhances loopback support by exposing new loopback modes
(e.g., MAC, SERDES) to userspace. These new modes are added extension
to the existing netdev features.

This allows users to select the loopback at specific layer.

Below are new modes added:

MAC near end loopback

MAC far end loopback

SERDES loopback

Depending on the feedback will submit ethtool changes.

Signed-off-by: Hariprasad Kelam <hkelam@marvell.com>
---
 Documentation/networking/netdev-features.rst  | 15 +++
 .../ethernet/marvell/octeontx2/nic/otx2_pf.c  | 93 ++++++++++++++++++-
 include/linux/netdev_features.h               |  9 +-
 net/ethtool/common.c                          |  3 +
 4 files changed, 116 insertions(+), 4 deletions(-)

diff --git a/Documentation/networking/netdev-features.rst b/Documentation/networking/netdev-features.rst
index 02bd7536fc0c..dcad5e875f32 100644
--- a/Documentation/networking/netdev-features.rst
+++ b/Documentation/networking/netdev-features.rst
@@ -193,3 +193,18 @@ frames in hardware.
 
 This should be set for devices which support netmem TX. See
 Documentation/networking/netmem.rst
+
+* mac-nearend-loopback
+
+This requests that the NIC enables MAC nearend loopback i.e egress traffic is
+routed back to ingress traffic.
+
+* mac-farend-loopback
+
+This requests that the NIC enables MAC farend loopback i.e ingress traffic is
+routed back to egress traffic.
+
+
+* serdes-loopback
+
+This request that the NIC enables SERDES near end digital loopback.
diff --git a/drivers/net/ethernet/marvell/octeontx2/nic/otx2_pf.c b/drivers/net/ethernet/marvell/octeontx2/nic/otx2_pf.c
index e808995703cf..14be6a9206c8 100644
--- a/drivers/net/ethernet/marvell/octeontx2/nic/otx2_pf.c
+++ b/drivers/net/ethernet/marvell/octeontx2/nic/otx2_pf.c
@@ -1316,6 +1316,84 @@ static int otx2_cgx_config_loopback(struct otx2_nic *pf, bool enable)
 	return err;
 }
 
+static int otx2_cgx_mac_nearend_loopback(struct otx2_nic *pf, bool enable)
+{
+	struct msg_req *msg;
+	int err;
+
+	if (enable && !bitmap_empty(pf->flow_cfg->dmacflt_bmap,
+				    pf->flow_cfg->dmacflt_max_flows))
+		netdev_warn(pf->netdev,
+			    "CGX/RPM nearend loopback might not work as DMAC filters are active\n");
+
+	mutex_lock(&pf->mbox.lock);
+	if (enable)
+		msg = otx2_mbox_alloc_msg_cgx_intlbk_enable(&pf->mbox);
+	else
+		msg = otx2_mbox_alloc_msg_cgx_intlbk_disable(&pf->mbox);
+
+	if (!msg) {
+		mutex_unlock(&pf->mbox.lock);
+		return -ENOMEM;
+	}
+
+	err = otx2_sync_mbox_msg(&pf->mbox);
+	mutex_unlock(&pf->mbox.lock);
+	return err;
+}
+
+static int otx2_cgx_mac_farend_loopback(struct otx2_nic *pf, bool enable)
+{
+	struct msg_req *msg;
+	int err;
+
+	if (enable && !bitmap_empty(pf->flow_cfg->dmacflt_bmap,
+				    pf->flow_cfg->dmacflt_max_flows))
+		netdev_warn(pf->netdev,
+			    "CGX/RPM farend loopback might not work as DMAC filters are active\n");
+
+	mutex_lock(&pf->mbox.lock);
+	if (enable)
+		msg = otx2_mbox_alloc_msg_cgx_intlbk_enable(&pf->mbox);
+	else
+		msg = otx2_mbox_alloc_msg_cgx_intlbk_disable(&pf->mbox);
+
+	if (!msg) {
+		mutex_unlock(&pf->mbox.lock);
+		return -ENOMEM;
+	}
+
+	err = otx2_sync_mbox_msg(&pf->mbox);
+	mutex_unlock(&pf->mbox.lock);
+	return err;
+}
+
+static int otx2_cgx_serdes_loopback(struct otx2_nic *pf, bool enable)
+{
+	struct msg_req *msg;
+	int err;
+
+	if (enable && !bitmap_empty(pf->flow_cfg->dmacflt_bmap,
+				    pf->flow_cfg->dmacflt_max_flows))
+		netdev_warn(pf->netdev,
+			    "CGX/RPM serdes loopback might not work as DMAC filters are active\n");
+
+	mutex_lock(&pf->mbox.lock);
+	if (enable)
+		msg = otx2_mbox_alloc_msg_cgx_intlbk_enable(&pf->mbox);
+	else
+		msg = otx2_mbox_alloc_msg_cgx_intlbk_disable(&pf->mbox);
+
+	if (!msg) {
+		mutex_unlock(&pf->mbox.lock);
+		return -ENOMEM;
+	}
+
+	err = otx2_sync_mbox_msg(&pf->mbox);
+	mutex_unlock(&pf->mbox.lock);
+	return err;
+}
+
 int otx2_set_real_num_queues(struct net_device *netdev,
 			     int tx_queues, int rx_queues)
 {
@@ -2363,6 +2441,18 @@ static int otx2_set_features(struct net_device *netdev,
 		return cn10k_ipsec_ethtool_init(netdev,
 						features & NETIF_F_HW_ESP);
 
+	if ((changed & NETIF_F_MAC_LBK_NE) && netif_running(netdev))
+		return otx2_cgx_mac_nearend_loopback(pf,
+						     features & NETIF_F_MAC_LBK_NE);
+
+	if ((changed & NETIF_F_MAC_LBK_FE) && netif_running(netdev))
+		return otx2_cgx_mac_farend_loopback(pf,
+						    features & NETIF_F_MAC_LBK_FE);
+
+	if ((changed & NETIF_F_SERDES_LBK) && netif_running(netdev))
+		return otx2_cgx_serdes_loopback(pf,
+						features & NETIF_F_SERDES_LBK);
+
 	return otx2_handle_ntuple_tc_features(netdev, features);
 }
 
@@ -3249,7 +3339,8 @@ static int otx2_probe(struct pci_dev *pdev, const struct pci_device_id *id)
 	if (pf->flags & OTX2_FLAG_TC_FLOWER_SUPPORT)
 		netdev->hw_features |= NETIF_F_HW_TC;
 
-	netdev->hw_features |= NETIF_F_LOOPBACK | NETIF_F_RXALL;
+	netdev->hw_features |= NETIF_F_LOOPBACK | NETIF_F_RXALL |
+			       NETIF_F_MAC_LBK_NE | NETIF_F_MAC_LBK_FE | NETIF_F_SERDES_LBK;
 
 	netif_set_tso_max_segs(netdev, OTX2_MAX_GSO_SEGS);
 	netdev->watchdog_timeo = OTX2_TX_TIMEOUT;
diff --git a/include/linux/netdev_features.h b/include/linux/netdev_features.h
index 93e4da7046a1..124f83223361 100644
--- a/include/linux/netdev_features.h
+++ b/include/linux/netdev_features.h
@@ -14,7 +14,7 @@ typedef u64 netdev_features_t;
 enum {
 	NETIF_F_SG_BIT,			/* Scatter/gather IO. */
 	NETIF_F_IP_CSUM_BIT,		/* Can checksum TCP/UDP over IPv4. */
-	__UNUSED_NETIF_F_1,
+	NETIF_F_MAC_LBK_NE_BIT,		/* MAC near end loopback */
 	NETIF_F_HW_CSUM_BIT,		/* Can checksum all the packets. */
 	NETIF_F_IPV6_CSUM_BIT,		/* Can checksum TCP/UDP over IPV6 */
 	NETIF_F_HIGHDMA_BIT,		/* Can DMA to high memory. */
@@ -24,8 +24,8 @@ enum {
 	NETIF_F_HW_VLAN_CTAG_FILTER_BIT,/* Receive filtering on VLAN CTAGs */
 	NETIF_F_VLAN_CHALLENGED_BIT,	/* Device cannot handle VLAN packets */
 	NETIF_F_GSO_BIT,		/* Enable software GSO. */
-	__UNUSED_NETIF_F_12,
-	__UNUSED_NETIF_F_13,
+	NETIF_F_MAC_LBK_FE_BIT,		/* MAC far end loopback */
+	NETIF_F_SERDES_LBK_BIT,		/* SERDES loopback */
 	NETIF_F_GRO_BIT,		/* Generic receive offload */
 	NETIF_F_LRO_BIT,		/* large receive offload */
 
@@ -165,6 +165,9 @@ enum {
 #define NETIF_F_HW_HSR_TAG_RM	__NETIF_F(HW_HSR_TAG_RM)
 #define NETIF_F_HW_HSR_FWD	__NETIF_F(HW_HSR_FWD)
 #define NETIF_F_HW_HSR_DUP	__NETIF_F(HW_HSR_DUP)
+#define NETIF_F_MAC_LBK_NE	__NETIF_F(MAC_LBK_NE)
+#define NETIF_F_MAC_LBK_FE	__NETIF_F(MAC_LBK_FE)
+#define NETIF_F_SERDES_LBK	__NETIF_F(SERDES_LBK)
 
 /* Finds the next feature with the highest number of the range of start-1 till 0.
  */
diff --git a/net/ethtool/common.c b/net/ethtool/common.c
index 55223ebc2a7e..4a6a400a7c69 100644
--- a/net/ethtool/common.c
+++ b/net/ethtool/common.c
@@ -77,6 +77,9 @@ const char netdev_features_strings[NETDEV_FEATURE_COUNT][ETH_GSTRING_LEN] = {
 	[NETIF_F_HW_HSR_TAG_RM_BIT] =	 "hsr-tag-rm-offload",
 	[NETIF_F_HW_HSR_FWD_BIT] =	 "hsr-fwd-offload",
 	[NETIF_F_HW_HSR_DUP_BIT] =	 "hsr-dup-offload",
+	[NETIF_F_MAC_LBK_NE_BIT] =	 "mac-nearend-loopback",
+	[NETIF_F_MAC_LBK_FE_BIT] =	 "mac-farend-loopback",
+	[NETIF_F_SERDES_LBK_BIT] =	 "serdes-loopback",
 };
 
 const char
-- 
2.34.1