net: dsa: Provide additional RMON statistics

Display sw_in_discards, sw_in_filtered, and sw_out_filtered for chips
supported by mv88e6123_61_65 and mv88e6352 drivers.

The variables are provided in port registers, not the normal status registers.
Mark by adding 0x100 to the register offset and add special handling code
to mv88e6xxx_get_ethtool_stats.

Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/dsa/mv88e6123_61_65.c

@@ -433,6 +433,9 @@ static struct mv88e6xxx_hw_stat mv88e6123_61_65_hw_stats[] = {
 	{ "hist_256_511bytes", 4, 0x0b, },
 	{ "hist_512_1023bytes", 4, 0x0c, },
 	{ "hist_1024_max_bytes", 4, 0x0d, },
+	{ "sw_in_discards", 4, 0x110, },
+	{ "sw_in_filtered", 2, 0x112, },
+	{ "sw_out_filtered", 2, 0x113, },
 };
 
 static void

drivers/net/dsa/mv88e6352.c

@@ -539,6 +539,9 @@ static struct mv88e6xxx_hw_stat mv88e6352_hw_stats[] = {
 	{ "hist_256_511bytes", 4, 0x0b, },
 	{ "hist_512_1023bytes", 4, 0x0c, },
 	{ "hist_1024_max_bytes", 4, 0x0d, },
+	{ "sw_in_discards", 4, 0x110, },
+	{ "sw_in_filtered", 2, 0x112, },
+	{ "sw_out_filtered", 2, 0x113, },
 };
 
 static int mv88e6352_read_eeprom_word(struct dsa_switch *ds, int addr)

drivers/net/dsa/mv88e6xxx.c

@@ -485,17 +485,33 @@ void mv88e6xxx_get_ethtool_stats(struct dsa_switch *ds,
 	for (i = 0; i < nr_stats; i++) {
 		struct mv88e6xxx_hw_stat *s = stats + i;
 		u32 low;
-		u32 high;
+		u32 high = 0;
 
+		if (s->reg >= 0x100) {
+			int ret;
+
+			ret = mv88e6xxx_reg_read(ds, REG_PORT(port),
+						 s->reg - 0x100);
+			if (ret < 0)
+				goto error;
+			low = ret;
+			if (s->sizeof_stat == 4) {
+				ret = mv88e6xxx_reg_read(ds, REG_PORT(port),
+							 s->reg - 0x100 + 1);
+				if (ret < 0)
+					goto error;
+				high = ret;
+			}
+			data[i] = (((u64)high) << 16) | low;
+			continue;
+		}
 		mv88e6xxx_stats_read(ds, s->reg, &low);
 		if (s->sizeof_stat == 8)
 			mv88e6xxx_stats_read(ds, s->reg + 1, &high);
-		else
-			high = 0;
 
 		data[i] = (((u64)high) << 32) | low;
 	}
-
+error:
 	mutex_unlock(&ps->stats_mutex);
 }