igc: set the RX packet buffer size for TSN mode

Author: Faizal Rahim <faizal.abdul.rahim@linux.intel.com>

In preparation for supporting frame preemption, when entering TSN mode,
set the receive packet buffer to 15KB for the Express MAC, 15KB for
the Preemptible MAC and 2KB for the BMC.

References:
I225/I226 SW User Manual, Section 4.7.9, Section 7.1.3.2, Section 8.3.1

The newly introduced macros follow the naming from the i226 SW User Manual
for easy reference.

Co-developed-by: Vinicius Costa Gomes <vinicius.gomes@intel.com>
Signed-off-by: Vinicius Costa Gomes <vinicius.gomes@intel.com>
Signed-off-by: Faizal Rahim <faizal.abdul.rahim@linux.intel.com>
Tested-by: Mor Bar-Gabay <morx.bar.gabay@intel.com>
Signed-off-by: Tony Nguyen <anthony.l.nguyen@intel.com>
(cherry picked from commit 7663370)
JIRA: https://issues.redhat.com/browse/RHEL-83575
Signed-off-by: Corinna Vinschen <vinschen@redhat.com>

Author: github-cygwin

drivers/net/ethernet/intel/igc/igc_defines.h

@@ -399,17 +399,22 @@
 /* Mask for RX packet buffer size */
 #define IGC_RXPBSIZE_EXP_MASK		GENMASK(5, 0)
 #define IGC_BMC2OSPBSIZE_MASK		GENMASK(11, 6)
+#define IGC_RXPBSIZE_BE_MASK		GENMASK(17, 12)
 /* Mask for timestamp in RX buffer */
 #define IGC_RXPBS_CFG_TS_EN_MASK	GENMASK(31, 31)
 /* High-priority RX packet buffer size (KB). Used for Express traffic when preemption is enabled */
 #define IGC_RXPBSIZE_EXP(x)		FIELD_PREP(IGC_RXPBSIZE_EXP_MASK, (x))
 /* BMC to OS packet buffer size in KB */
 #define IGC_BMC2OSPBSIZE(x)		FIELD_PREP(IGC_BMC2OSPBSIZE_MASK, (x))
+/* Low-priority RX packet buffer size (KB). Used for BE traffic when preemption is enabled */
+#define IGC_RXPBSIZE_BE(x)		FIELD_PREP(IGC_RXPBSIZE_BE_MASK, (x))
 /* Enable RX packet buffer for timestamp descriptor, saving 16 bytes per packet if set */
 #define IGC_RXPBS_CFG_TS_EN		FIELD_PREP(IGC_RXPBS_CFG_TS_EN_MASK, 1)
 /* Default value following I225/I226 SW User Manual Section 8.3.1 */
 #define IGC_RXPBSIZE_EXP_BMC_DEFAULT ( \
 	IGC_RXPBSIZE_EXP(34) | IGC_BMC2OSPBSIZE(2))
+#define IGC_RXPBSIZE_EXP_BMC_BE_TSN ( \
+	IGC_RXPBSIZE_EXP(15) | IGC_BMC2OSPBSIZE(2) | IGC_RXPBSIZE_BE(15))
 
 /* Mask for TX packet buffer size */
 #define IGC_TXPB0SIZE_MASK		GENMASK(5, 0)

drivers/net/ethernet/intel/igc/igc_tsn.c

@@ -125,6 +125,29 @@ static void igc_tsn_tx_arb(struct igc_adapter *adapter, u16 *queue_per_tc)
 	wr32(IGC_TXARB, txarb);
 }
 
+/**
+ * igc_tsn_set_rxpbsize - Set the receive packet buffer size
+ * @adapter: Pointer to the igc_adapter structure
+ * @rxpbs_exp_bmc_be: Value to set the receive packet buffer size, including
+ *                    express buffer, BMC buffer, and Best Effort buffer
+ *
+ * The IGC_RXPBS register value may include allocations for the Express buffer,
+ * BMC buffer, Best Effort buffer, and the timestamp descriptor buffer
+ * (IGC_RXPBS_CFG_TS_EN).
+ */
+static void igc_tsn_set_rxpbsize(struct igc_adapter *adapter,
+				 u32 rxpbs_exp_bmc_be)
+{
+	struct igc_hw *hw = &adapter->hw;
+	u32 rxpbs = rd32(IGC_RXPBS);
+
+	rxpbs &= ~(IGC_RXPBSIZE_EXP_MASK | IGC_BMC2OSPBSIZE_MASK |
+		   IGC_RXPBSIZE_BE_MASK);
+	rxpbs |= rxpbs_exp_bmc_be;
+
+	wr32(IGC_RXPBS, rxpbs);
+}
+
 /* Returns the TSN specific registers to their default values after
  * the adapter is reset.
  */
@@ -139,6 +162,8 @@ static int igc_tsn_disable_offload(struct igc_adapter *adapter)
 	wr32(IGC_TXPBS, IGC_TXPBSIZE_DEFAULT);
 	wr32(IGC_DTXMXPKTSZ, IGC_DTXMXPKTSZ_DEFAULT);
 
+	igc_tsn_set_rxpbsize(adapter, IGC_RXPBSIZE_EXP_BMC_DEFAULT);
+
 	if (igc_is_device_id_i226(hw))
 		igc_tsn_restore_retx_default(adapter);
 
@@ -202,6 +227,8 @@ static int igc_tsn_enable_offload(struct igc_adapter *adapter)
 	wr32(IGC_DTXMXPKTSZ, IGC_DTXMXPKTSZ_TSN);
 	wr32(IGC_TXPBS, IGC_TXPBSIZE_TSN);
 
+	igc_tsn_set_rxpbsize(adapter, IGC_RXPBSIZE_EXP_BMC_BE_TSN);
+
 	if (igc_is_device_id_i226(hw))
 		igc_tsn_set_retx_qbvfullthreshold(adapter);