net: systemport: fix software maintained statistics

Commit 60b4ea1 ("net: systemport: log RX buffer allocation and RX/TX DMA
failures") added a few software maintained statistics using
BCM_SYSPORT_STAT_MIB_RX and BCM_SYSPORT_STAT_MIB_TX. These statistics are read
from the hardware MIB counters, such that bcm_sysport_update_mib_counters() was
trying to read from a non-existing MIB offset for these counters.

Fix this by introducing a special type: BCM_SYSPORT_STAT_SOFT, similar to
BCM_SYSPORT_STAT_NETDEV, such that bcm_sysport_get_ethtool_stats will read from
the software mib.

Fixes: 60b4ea1 ("net: systemport: log RX buffer allocation and RX/TX DMA failures")
Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/broadcom/bcmsysport.c

@@ -274,9 +274,9 @@ 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),
-	STAT_MIB_RX("alloc_rx_buff_failed", mib.alloc_rx_buff_failed),
-	STAT_MIB_RX("rx_dma_failed", mib.rx_dma_failed),
-	STAT_MIB_TX("tx_dma_failed", mib.tx_dma_failed),
+	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),
 };
 
 #define BCM_SYSPORT_STATS_LEN	ARRAY_SIZE(bcm_sysport_gstrings_stats)
@@ -345,6 +345,7 @@ static void bcm_sysport_update_mib_counters(struct bcm_sysport_priv *priv)
 		s = &bcm_sysport_gstrings_stats[i];
 		switch (s->type) {
 		case BCM_SYSPORT_STAT_NETDEV:
+		case BCM_SYSPORT_STAT_SOFT:
 			continue;
 		case BCM_SYSPORT_STAT_MIB_RX:
 		case BCM_SYSPORT_STAT_MIB_TX:

drivers/net/ethernet/broadcom/bcmsysport.h

@@ -570,6 +570,7 @@ enum bcm_sysport_stat_type {
 	BCM_SYSPORT_STAT_RUNT,
 	BCM_SYSPORT_STAT_RXCHK,
 	BCM_SYSPORT_STAT_RBUF,
+	BCM_SYSPORT_STAT_SOFT,
 };
 
 /* Macros to help define ethtool statistics */
@@ -590,6 +591,7 @@ enum bcm_sysport_stat_type {
 #define STAT_MIB_RX(str, m) STAT_MIB(str, m, BCM_SYSPORT_STAT_MIB_RX)
 #define STAT_MIB_TX(str, m) STAT_MIB(str, m, BCM_SYSPORT_STAT_MIB_TX)
 #define STAT_RUNT(str, m) STAT_MIB(str, m, BCM_SYSPORT_STAT_RUNT)
+#define STAT_MIB_SOFT(str, m) STAT_MIB(str, m, BCM_SYSPORT_STAT_SOFT)
 
 #define STAT_RXCHK(str, m, ofs) { \
 	.stat_string = str, \