[PATCH net-next 2/2] net: dsa: microchip: implement microchip,no-tag-protocol flag

[vtpieter@gmail.com]

From: Pieter Van Trappen <pieter.van.trappen@cern.ch>

Implement microchip,no-tag-protocol flag to allow disabling the
switch' tagging protocol. For cases where the CPU MAC does not support
MTU size > 1500 such as the Zynq GEM.

This code was tested with a KSZ8794 chip.

Signed-off-by: Pieter Van Trappen <pieter.van.trappen@cern.ch>
---
 drivers/net/dsa/microchip/ksz8795.c      |  2 +-
 drivers/net/dsa/microchip/ksz9477.c      |  2 +-
 drivers/net/dsa/microchip/ksz_common.c   | 11 ++++++++---
 drivers/net/dsa/microchip/ksz_common.h   |  1 +
 drivers/net/dsa/microchip/lan937x_main.c |  2 +-
 5 files changed, 12 insertions(+), 6 deletions(-)

diff --git a/drivers/net/dsa/microchip/ksz8795.c b/drivers/net/dsa/microchip/ksz8795.c
index d27b9c36d73f..0442341d6d0f 100644
--- a/drivers/net/dsa/microchip/ksz8795.c
+++ b/drivers/net/dsa/microchip/ksz8795.c
@@ -1604,7 +1604,7 @@ void ksz8_config_cpu_port(struct dsa_switch *ds)
 	masks = dev->info->masks;
 	regs = dev->info->regs;
 
-	ksz_cfg(dev, regs[S_TAIL_TAG_CTRL], masks[SW_TAIL_TAG_ENABLE], true);
+	ksz_cfg(dev, regs[S_TAIL_TAG_CTRL], masks[SW_TAIL_TAG_ENABLE], !dev->no_tag_proto);
 
 	ksz8_port_setup(dev, dev->cpu_port, true);
 
diff --git a/drivers/net/dsa/microchip/ksz9477.c b/drivers/net/dsa/microchip/ksz9477.c
index 425e20daf1e9..a3c68751f258 100644
--- a/drivers/net/dsa/microchip/ksz9477.c
+++ b/drivers/net/dsa/microchip/ksz9477.c
@@ -1195,7 +1195,7 @@ void ksz9477_port_setup(struct ksz_device *dev, int port, bool cpu_port)
 	/* enable tag tail for host port */
 	if (cpu_port)
 		ksz_port_cfg(dev, port, REG_PORT_CTRL_0, PORT_TAIL_TAG_ENABLE,
-			     true);
+			     !dev->no_tag_proto);
 
 	ksz9477_port_queue_split(dev, port);
 
diff --git a/drivers/net/dsa/microchip/ksz_common.c b/drivers/net/dsa/microchip/ksz_common.c
index b074b4bb0629..fbbf26e940bc 100644
--- a/drivers/net/dsa/microchip/ksz_common.c
+++ b/drivers/net/dsa/microchip/ksz_common.c
@@ -2882,9 +2882,7 @@ static enum dsa_tag_protocol ksz_get_tag_protocol(struct dsa_switch *ds,
 	struct ksz_device *dev = ds->priv;
 	enum dsa_tag_protocol proto = DSA_TAG_PROTO_NONE;
 
-	if (dev->chip_id == KSZ8795_CHIP_ID ||
-	    dev->chip_id == KSZ8794_CHIP_ID ||
-	    dev->chip_id == KSZ8765_CHIP_ID)
+	if (ksz_is_ksz87xx(dev))
 		proto = DSA_TAG_PROTO_KSZ8795;
 
 	if (dev->chip_id == KSZ8830_CHIP_ID ||
@@ -2903,6 +2901,9 @@ static enum dsa_tag_protocol ksz_get_tag_protocol(struct dsa_switch *ds,
 	if (is_lan937x(dev))
 		proto = DSA_TAG_PROTO_LAN937X;
 
+	if (dev->no_tag_proto)
+		proto = DSA_TAG_PROTO_NONE;
+
 	return proto;
 }
 
@@ -2912,6 +2913,8 @@ static int ksz_connect_tag_protocol(struct dsa_switch *ds,
 	struct ksz_tagger_data *tagger_data;
 
 	switch (proto) {
+	case DSA_TAG_PROTO_NONE:
+		return 0;
 	case DSA_TAG_PROTO_KSZ8795:
 		return 0;
 	case DSA_TAG_PROTO_KSZ9893:
@@ -4459,6 +4462,8 @@ int ksz_switch_register(struct ksz_device *dev)
 
 		dev->wakeup_source = of_property_read_bool(dev->dev->of_node,
 							   "wakeup-source");
+		dev->no_tag_proto = of_property_read_bool(dev->dev->of_node,
+							  "microchip,no-tag-protocol");
 	}
 
 	ret = dsa_register_switch(dev->ds);
diff --git a/drivers/net/dsa/microchip/ksz_common.h b/drivers/net/dsa/microchip/ksz_common.h
index 5f0a628b9849..19cc0dd0ac03 100644
--- a/drivers/net/dsa/microchip/ksz_common.h
+++ b/drivers/net/dsa/microchip/ksz_common.h
@@ -174,6 +174,7 @@ struct ksz_device {
 	bool synclko_125;
 	bool synclko_disable;
 	bool wakeup_source;
+	bool no_tag_proto;
 
 	struct vlan_table *vlan_cache;
 
diff --git a/drivers/net/dsa/microchip/lan937x_main.c b/drivers/net/dsa/microchip/lan937x_main.c
index 824d9309a3d3..a9345da31ef5 100644
--- a/drivers/net/dsa/microchip/lan937x_main.c
+++ b/drivers/net/dsa/microchip/lan937x_main.c
@@ -182,7 +182,7 @@ void lan937x_port_setup(struct ksz_device *dev, int port, bool cpu_port)
 	/* enable tag tail for host port */
 	if (cpu_port)
 		lan937x_port_cfg(dev, port, REG_PORT_CTRL_0,
-				 PORT_TAIL_TAG_ENABLE, true);
+				 PORT_TAIL_TAG_ENABLE, !dev->no_tag_proto);
 
 	/* Enable the Port Queue split */
 	ksz9477_port_queue_split(dev, port);
-- 
2.43.0