octeontx2-af: Adjust Tx credits when MCS external bypass is disabled

When MCS external bypass is disabled, MCS returns additional
2 credits(32B) for every packet Tx'ed on LMAC. To account for
these extra credits, NIX_AF_TX_LINKX_NORM_CREDIT.CC_MCS_CNT
needs to be configured as otherwise NIX Tx credits would overflow
and will never be returned to idle state credit count
causing issues with credit control and MTU change.

This patch fixes the same by configuring CC_MCS_CNT at probe
time for MCS enabled SoC's

Fixes: bd69476 ("octeontx2-af: cn10k: mcs: Install a default TCAM for normal traffic")
Signed-off-by: Nithin Dabilpuram <[email protected]>
Signed-off-by: Geetha sowjanya <[email protected]>
Signed-off-by: Sunil Goutham <[email protected]>
Reviewed-by: Wojciech Drewek <[email protected]>
Signed-off-by: Paolo Abeni <[email protected]>

Author: nithind1988

drivers/net/ethernet/marvell/octeontx2/af/mcs.c

@@ -1219,6 +1219,17 @@ struct mcs *mcs_get_pdata(int mcs_id)
 	return NULL;
 }
 
+bool is_mcs_bypass(int mcs_id)
+{
+	struct mcs *mcs_dev;
+
+	list_for_each_entry(mcs_dev, &mcs_list, mcs_list) {
+		if (mcs_dev->mcs_id == mcs_id)
+			return mcs_dev->bypass;
+	}
+	return true;
+}
+
 void mcs_set_port_cfg(struct mcs *mcs, struct mcs_port_cfg_set_req *req)
 {
 	u64 val = 0;
@@ -1436,7 +1447,7 @@ static int mcs_x2p_calibration(struct mcs *mcs)
 	return err;
 }
 
-static void mcs_set_external_bypass(struct mcs *mcs, u8 bypass)
+static void mcs_set_external_bypass(struct mcs *mcs, bool bypass)
 {
 	u64 val;
 
@@ -1447,6 +1458,7 @@ static void mcs_set_external_bypass(struct mcs *mcs, u8 bypass)
 	else
 		val &= ~BIT_ULL(6);
 	mcs_reg_write(mcs, MCSX_MIL_GLOBAL, val);
+	mcs->bypass = bypass;
 }
 
 static void mcs_global_cfg(struct mcs *mcs)

drivers/net/ethernet/marvell/octeontx2/af/mcs.h

@@ -149,6 +149,7 @@ struct mcs {
 	u16			num_vec;
 	void			*rvu;
 	u16			*tx_sa_active;
+	bool                      bypass;
 };
 
 struct mcs_ops {
@@ -206,6 +207,7 @@ void mcs_get_custom_tag_cfg(struct mcs *mcs, struct mcs_custom_tag_cfg_get_req *
 int mcs_alloc_ctrlpktrule(struct rsrc_bmap *rsrc, u16 *pf_map, u16 offset, u16 pcifunc);
 int mcs_free_ctrlpktrule(struct mcs *mcs, struct mcs_free_ctrl_pkt_rule_req *req);
 int mcs_ctrlpktrule_write(struct mcs *mcs, struct mcs_ctrl_pkt_rule_write_req *req);
+bool is_mcs_bypass(int mcs_id);
 
 /* CN10K-B APIs */
 void cn10kb_mcs_set_hw_capabilities(struct mcs *mcs);

drivers/net/ethernet/marvell/octeontx2/af/rvu.h

@@ -345,6 +345,7 @@ struct nix_hw {
 	struct nix_txvlan txvlan;
 	struct nix_ipolicer *ipolicer;
 	u64    *tx_credits;
+	u8	cc_mcs_cnt;
 };
 
 /* RVU block's capabilities or functionality,

drivers/net/ethernet/marvell/octeontx2/af/rvu_nix.c

@@ -12,6 +12,7 @@
 #include "rvu_reg.h"
 #include "rvu.h"
 #include "npc.h"
+#include "mcs.h"
 #include "cgx.h"
 #include "lmac_common.h"
 #include "rvu_npc_hash.h"
@@ -4389,6 +4390,12 @@ static void nix_link_config(struct rvu *rvu, int blkaddr,
 			    SDP_HW_MAX_FRS << 16 | NIC_HW_MIN_FRS);
 	}
 
+	/* Get MCS external bypass status for CN10K-B */
+	if (mcs_get_blkcnt() == 1) {
+		/* Adjust for 2 credits when external bypass is disabled */
+		nix_hw->cc_mcs_cnt = is_mcs_bypass(0) ? 0 : 2;
+	}
+
 	/* Set credits for Tx links assuming max packet length allowed.
 	 * This will be reconfigured based on MTU set for PF/VF.
 	 */
@@ -4412,6 +4419,7 @@ static void nix_link_config(struct rvu *rvu, int blkaddr,
 			tx_credits = (lmac_fifo_len - lmac_max_frs) / 16;
 			/* Enable credits and set credit pkt count to max allowed */
 			cfg =  (tx_credits << 12) | (0x1FF << 2) | BIT_ULL(1);
+			cfg |= FIELD_PREP(NIX_AF_LINKX_MCS_CNT_MASK, nix_hw->cc_mcs_cnt);
 
 			link = iter + slink;
 			nix_hw->tx_credits[link] = tx_credits;

drivers/net/ethernet/marvell/octeontx2/af/rvu_reg.h

@@ -437,6 +437,7 @@
 
 #define NIX_AF_LINKX_BASE_MASK		GENMASK_ULL(11, 0)
 #define NIX_AF_LINKX_RANGE_MASK		GENMASK_ULL(19, 16)
+#define NIX_AF_LINKX_MCS_CNT_MASK	GENMASK_ULL(33, 32)
 
 /* SSO */
 #define SSO_AF_CONST			(0x1000)