net: dsa: felix: create a template for the DSA tags on xmit

With this patch we try to kill 2 birds with 1 stone.

First of all, some switches that use tag_ocelot.c don't have the exact
same bitfield layout for the DSA tags. The destination ports field is
different for Seville VSC9953 for example. So the choices are to either
duplicate tag_ocelot.c into a new tag_seville.c (sub-optimal) or somehow
take into account a supposed ocelot->dest_ports_offset when packing this
field into the DSA injection header (again not ideal).

Secondly, tag_ocelot.c already needs to memset a 128-bit area to zero
and call some packing() functions of dubious performance in the
fastpath. And most of the values it needs to pack are pretty much
constant (BYPASS=1, SRC_PORT=CPU, DEST=port index). So it would be good
if we could improve that.

The proposed solution is to allocate a memory area per port at probe
time, initialize that with the statically defined bits as per chip
hardware revision, and just perform a simpler memcpy in the fastpath.

Other alternatives have been analyzed, such as:
- Create a separate tag_seville.c: too much code duplication for just 1
  bit field difference.
- Create a separate DSA_TAG_PROTO_SEVILLE under tag_ocelot.c, just like
  tag_brcm.c, which would have a separate .xmit function. Again, too
  much code duplication for just 1 bit field difference.
- Allocate the template from the init function of the tag_ocelot.c
  module, instead of from the driver: couldn't figure out a method of
  accessing the correct port template corresponding to the correct
  tagger in the .xmit function.

Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Reviewed-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 13 insertions, 0 deletions

diff --git a/drivers/net/dsa/ocelot/felix.c b/drivers/net/dsa/ocelot/felix.c
index 4b255ed614e4..b9981d8c4c98 100644
--- a/drivers/net/dsa/ocelot/felix.c
+++ b/drivers/net/dsa/ocelot/felix.c
@@ -522,6 +522,7 @@ static int felix_init_structs(struct felix *felix, int num_phys_ports)
 	for (port = 0; port < num_phys_ports; port++) {
 		struct ocelot_port *ocelot_port;
 		struct regmap *target;
+		u8 *template;
 
 		ocelot_port = devm_kzalloc(ocelot->dev,
 					   sizeof(struct ocelot_port),
@@ -547,10 +548,22 @@ static int felix_init_structs(struct felix *felix, int num_phys_ports)
 			return PTR_ERR(target);
 		}
 
+		template = devm_kzalloc(ocelot->dev, OCELOT_TAG_LEN,
+					GFP_KERNEL);
+		if (!template) {
+			dev_err(ocelot->dev,
+				"Failed to allocate memory for DSA tag\n");
+			kfree(port_phy_modes);
+			return -ENOMEM;
+		}
+
 		ocelot_port->phy_mode = port_phy_modes[port];
 		ocelot_port->ocelot = ocelot;
 		ocelot_port->target = target;
+		ocelot_port->xmit_template = template;
 		ocelot->ports[port] = ocelot_port;
+
+		felix->info->xmit_template_populate(ocelot, port);
 	}
 
 	kfree(port_phy_modes);