[PATCH v2 net-next 20/22] net: dsa: sja1105: Reject unsupported link modes for AN

[Vladimir Oltean <olteanv@gmail.com>]

Ethernet flow control:

The switch MAC does not consume, nor does it emit pause frames. It
simply forwards them as any other Ethernet frame (and since the DMAC is,
per IEEE spec, 01-80-C2-00-00-01, it means they are filtered as
link-local traffic and forwarded to the CPU, which can't do anything
useful with them).

Duplex:

There is no duplex setting in the SJA1105 MAC. It is known to forward
traffic at line rate on the same port in both directions. Therefore it
must be that it only supports full duplex.

Signed-off-by: Vladimir Oltean <olteanv@gmail.com>
---
Changes in v2:
Patch is new.

 drivers/net/dsa/sja1105/sja1105_main.c | 31 ++++++++++++++++++++++++++
 1 file changed, 31 insertions(+)

diff --git a/drivers/net/dsa/sja1105/sja1105_main.c b/drivers/net/dsa/sja1105/sja1105_main.c
index 04fdca788a87..6dca2036f910 100644
--- a/drivers/net/dsa/sja1105/sja1105_main.c
+++ b/drivers/net/dsa/sja1105/sja1105_main.c
@@ -11,6 +11,7 @@
 #include <linux/spi/spi.h>
 #include <linux/errno.h>
 #include <linux/gpio/consumer.h>
+#include <linux/phylink.h>
 #include <linux/of.h>
 #include <linux/of_net.h>
 #include <linux/of_mdio.h>
@@ -747,6 +748,35 @@ static void sja1105_adjust_link(struct dsa_switch *ds, int port,
 		sja1105_adjust_port_config(priv, port, phydev->speed, true);
 }
 
+static void sja1105_phylink_validate(struct dsa_switch *ds, int port,
+				     unsigned long *supported,
+				     struct phylink_link_state *state)
+{
+	/* Construct a new mask which exhaustively contains all link features
+	 * supported by the MAC, and then apply that (logical AND) to what will
+	 * be sent to the PHY for "marketing".
+	 */
+	__ETHTOOL_DECLARE_LINK_MODE_MASK(mask) = { 0, };
+	struct sja1105_private *priv = ds->priv;
+	struct sja1105_xmii_params_entry *mii;
+
+	mii = priv->static_config.tables[BLK_IDX_XMII_PARAMS].entries;
+
+	/* The MAC does not support pause frames, and also doesn't
+	 * support half-duplex traffic modes.
+	 */
+	phylink_set(mask, Autoneg);
+	phylink_set(mask, MII);
+	phylink_set(mask, 10baseT_Full);
+	phylink_set(mask, 100baseT_Full);
+	if (mii->xmii_mode[port] == XMII_MODE_RGMII)
+		phylink_set(mask, 1000baseT_Full);
+
+	bitmap_and(supported, supported, mask, __ETHTOOL_LINK_MODE_MASK_NBITS);
+	bitmap_and(state->advertising, state->advertising, mask,
+		   __ETHTOOL_LINK_MODE_MASK_NBITS);
+}
+
 #define fdb(bin, index) \
 	((bin) * SJA1105ET_FDB_BIN_SIZE + (index))
 #define is_bin_index_valid(i) \
@@ -1482,6 +1512,7 @@ static const struct dsa_switch_ops sja1105_switch_ops = {
 	.get_tag_protocol	= sja1105_get_tag_protocol,
 	.setup			= sja1105_setup,
 	.adjust_link		= sja1105_adjust_link,
+	.phylink_validate	= sja1105_phylink_validate,
 	.get_strings		= sja1105_get_strings,
 	.get_ethtool_stats	= sja1105_get_ethtool_stats,
 	.get_sset_count		= sja1105_get_sset_count,
-- 
2.17.1