net: dsa: tag_sja1105: be dsa_loop-safe

Add support for tag_sja1105 running on non-sja1105 DSA ports, by making
sure that every time we dereference dp->priv, we check the switch's
dsa_switch_ops (otherwise we access a struct sja1105_port structure that
is in fact something else).

This adds an unconditional build-time dependency between sja1105 being
built as module => tag_sja1105 must also be built as module. This was
there only for PTP before.

Some sane defaults must also take place when not running on sja1105
hardware. These are:

- sja1105_xmit_tpid: the sja1105 driver uses different VLAN protocols
  depending on VLAN awareness and switch revision (when an encapsulated
  VLAN must be sent). Default to 0x8100.

- sja1105_rcv_meta_state_machine: this aggregates PTP frames with their
  metadata timestamp frames. When running on non-sja1105 hardware, don't
  do that and accept all frames unmodified.

- sja1105_defer_xmit: calls sja1105_port_deferred_xmit in sja1105_main.c
  which writes a management route over SPI. When not running on sja1105
  hardware, bypass the SPI write and send the frame as-is.

Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 2 insertions, 3 deletions

diff --git a/drivers/net/dsa/sja1105/sja1105_main.c b/drivers/net/dsa/sja1105/sja1105_main.c
index fe894dc18335..05ba65042b5f 100644
--- a/drivers/net/dsa/sja1105/sja1105_main.c
+++ b/drivers/net/dsa/sja1105/sja1105_main.c
@@ -28,8 +28,6 @@
 #define SJA1105_UNKNOWN_MULTICAST	0x010000000000ull
 #define SJA1105_DEFAULT_VLAN		(VLAN_N_VID - 1)
 
-static const struct dsa_switch_ops sja1105_switch_ops;
-
 static void sja1105_hw_reset(struct gpio_desc *gpio, unsigned int pulse_len,
 			     unsigned int startup_delay)
 {
@@ -3100,7 +3098,7 @@ static void sja1105_teardown(struct dsa_switch *ds)
 	sja1105_static_config_free(&priv->static_config);
 }
 
-static const struct dsa_switch_ops sja1105_switch_ops = {
+const struct dsa_switch_ops sja1105_switch_ops = {
 	.get_tag_protocol	= sja1105_get_tag_protocol,
 	.setup			= sja1105_setup,
 	.teardown		= sja1105_teardown,
@@ -3149,6 +3147,7 @@ static const struct dsa_switch_ops sja1105_switch_ops = {
 	.port_bridge_tx_fwd_offload = dsa_tag_8021q_bridge_tx_fwd_offload,
 	.port_bridge_tx_fwd_unoffload = dsa_tag_8021q_bridge_tx_fwd_unoffload,
 };
+EXPORT_SYMBOL_GPL(sja1105_switch_ops);
 
 static const struct of_device_id sja1105_dt_ids[];