net: systemport: Add support for RDMA overflow statistic counter

RDMA overflows can happen if the Ethernet controller does not have
enough bandwidth allocated at the memory controller level, report RDMA
overflows and deal with saturation, similar to the RBUF overflow
counter.

Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>
Link: https://lore.kernel.org/r/20221028222141.3208429-1-f.fainelli@gmail.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

drivers/net/ethernet/broadcom/bcmsysport.c

@@ -295,6 +295,8 @@ static const struct bcm_sysport_stats bcm_sysport_gstrings_stats[] = {
 	/* RBUF misc statistics */
 	STAT_RBUF("rbuf_ovflow_cnt", mib.rbuf_ovflow_cnt, RBUF_OVFL_DISC_CNTR),
 	STAT_RBUF("rbuf_err_cnt", mib.rbuf_err_cnt, RBUF_ERR_PKT_CNTR),
+	/* RDMA misc statistics */
+	STAT_RDMA("rdma_ovflow_cnt", mib.rdma_ovflow_cnt, RDMA_OVFL_DISC_CNTR),
 	STAT_MIB_SOFT("alloc_rx_buff_failed", mib.alloc_rx_buff_failed),
 	STAT_MIB_SOFT("rx_dma_failed", mib.rx_dma_failed),
 	STAT_MIB_SOFT("tx_dma_failed", mib.tx_dma_failed),
@@ -333,6 +335,7 @@ static inline bool bcm_sysport_lite_stat_valid(enum bcm_sysport_stat_type type)
 	case BCM_SYSPORT_STAT_NETDEV64:
 	case BCM_SYSPORT_STAT_RXCHK:
 	case BCM_SYSPORT_STAT_RBUF:
+	case BCM_SYSPORT_STAT_RDMA:
 	case BCM_SYSPORT_STAT_SOFT:
 		return true;
 	default:
@@ -436,6 +439,14 @@ static void bcm_sysport_update_mib_counters(struct bcm_sysport_priv *priv)
 			if (val == ~0)
 				rbuf_writel(priv, 0, s->reg_offset);
 			break;
+		case BCM_SYSPORT_STAT_RDMA:
+			if (!priv->is_lite)
+				continue;
+
+			val = rdma_readl(priv, s->reg_offset);
+			if (val == ~0)
+				rdma_writel(priv, 0, s->reg_offset);
+			break;
 		}
 
 		j += s->stat_sizeof;

drivers/net/ethernet/broadcom/bcmsysport.h

@@ -290,6 +290,7 @@ struct bcm_rsb {
 
 #define RDMA_WRITE_PTR_HI		0x1010
 #define RDMA_WRITE_PTR_LO		0x1014
+#define RDMA_OVFL_DISC_CNTR		0x1018
 #define RDMA_PROD_INDEX			0x1018
 #define  RDMA_PROD_INDEX_MASK		0xffff
 
@@ -565,6 +566,7 @@ struct bcm_sysport_mib {
 	u32 rxchk_other_pkt_disc;
 	u32 rbuf_ovflow_cnt;
 	u32 rbuf_err_cnt;
+	u32 rdma_ovflow_cnt;
 	u32 alloc_rx_buff_failed;
 	u32 rx_dma_failed;
 	u32 tx_dma_failed;
@@ -581,6 +583,7 @@ enum bcm_sysport_stat_type {
 	BCM_SYSPORT_STAT_RUNT,
 	BCM_SYSPORT_STAT_RXCHK,
 	BCM_SYSPORT_STAT_RBUF,
+	BCM_SYSPORT_STAT_RDMA,
 	BCM_SYSPORT_STAT_SOFT,
 };
 
@@ -627,6 +630,14 @@ enum bcm_sysport_stat_type {
 	.reg_offset = ofs, \
 }
 
+#define STAT_RDMA(str, m, ofs) { \
+	.stat_string = str, \
+	.stat_sizeof = sizeof(((struct bcm_sysport_priv *)0)->m), \
+	.stat_offset = offsetof(struct bcm_sysport_priv, m), \
+	.type = BCM_SYSPORT_STAT_RDMA, \
+	.reg_offset = ofs, \
+}
+
 /* TX bytes and packets */
 #define NUM_SYSPORT_TXQ_STAT	2