igc: add preemptible queue support in taprio

Changes:
1. Introduce tx_enabled flag to control preemptible queue. tx_enabled
   is set via mmsv module based on multiple factors, including link
   up/down status, to determine if FPE is active or inactive.
2. Add priority field to TXDCTL for express queue to improve data
   fetch performance.
3. Block preemptible queue setup in taprio unless reverse-tsn-txq-prio
   private flag is set. Encourages adoption of standard queue priority
   scheme for new features.
4. Hardware-padded frames from preemptible queues result in incorrect
   mCRC values, as padding bytes are excluded from the computation. Pad
   frames to at least 60 bytes using skb_padto() before transmission to
   ensure the hardware includes padding in the mCRC calculation.

Tested preemption with taprio by:
1. Enable FPE:
   ethtool --set-mm enp1s0 pmac-enabled on tx-enabled on verify-enabled on
2. Enable private flag to reverse TX queue priority:
   ethtool --set-priv-flags enp1s0 reverse-txq-prio on
3. Enable preemptible queue in taprio:
   taprio num_tc 4 map 0 1 2 3 0 0 0 0 0 0 0 0 0 0 0 0 \
   queues 1@0 1@1 1@2 1@3 \
   fp P P P E

Reviewed-by: Aleksandr Loktionov <aleksandr.loktionov@intel.com>
Co-developed-by: Chwee-Lin Choong <chwee.lin.choong@intel.com>
Signed-off-by: Chwee-Lin Choong <chwee.lin.choong@intel.com>
Signed-off-by: Faizal Rahim <faizal.abdul.rahim@linux.intel.com>
Reviewed-by: Simon Horman <horms@kernel.org>
Tested-by: Mor Bar-Gabay <morx.bar.gabay@intel.com>
Signed-off-by: Tony Nguyen <anthony.l.nguyen@intel.com>

1 files changed, 4 insertions, 0 deletions

diff --git a/drivers/net/ethernet/intel/igc/igc_tsn.h b/drivers/net/ethernet/intel/igc/igc_tsn.h
index c2a77229207b..f2e8bfef4871 100644
--- a/drivers/net/ethernet/intel/igc/igc_tsn.h
+++ b/drivers/net/ethernet/intel/igc/igc_tsn.h
@@ -4,6 +4,8 @@
 #ifndef _IGC_TSN_H_
 #define _IGC_TSN_H_
 
+#include <net/pkt_sched.h>
+
 #define IGC_RX_MIN_FRAG_SIZE		60
 #define SMD_FRAME_SIZE			60
 
@@ -15,6 +17,8 @@ enum igc_txd_popts_type {
 DECLARE_STATIC_KEY_FALSE(igc_fpe_enabled);
 
 void igc_fpe_init(struct igc_adapter *adapter);
+void igc_fpe_save_preempt_queue(struct igc_adapter *adapter,
+				const struct tc_mqprio_qopt_offload *mqprio);
 u32 igc_fpe_get_supported_frag_size(u32 frag_size);
 int igc_tsn_offload_apply(struct igc_adapter *adapter);
 int igc_tsn_reset(struct igc_adapter *adapter);