net: airoha: Add the capability to allocate hfwd descriptors in SRAM

In order to improve packet processing and packet forwarding
performances, EN7581 SoC supports consuming SRAM instead of DRAM for
hw forwarding descriptors queue.
For downlink hw accelerated traffic request to consume SRAM memory
for hw forwarding descriptors queue.

Signed-off-by: Lorenzo Bianconi <lorenzo@kernel.org>
Reviewed-by: Simon Horman <horms@kernel.org>
Link: https://patch.msgid.link/20250521-airopha-desc-sram-v3-4-a6e9b085b4f0@kernel.org
Signed-off-by: Paolo Abeni <pabeni@redhat.com>

Author: LorenzoBianconi

drivers/net/ethernet/airoha/airoha_eth.c

@@ -71,15 +71,6 @@ static void airoha_qdma_irq_disable(struct airoha_irq_bank *irq_bank,
 	airoha_qdma_set_irqmask(irq_bank, index, mask, 0);
 }
 
-static bool airhoa_is_lan_gdm_port(struct airoha_gdm_port *port)
-{
-	/* GDM1 port on EN7581 SoC is connected to the lan dsa switch.
-	 * GDM{2,3,4} can be used as wan port connected to an external
-	 * phy module.
-	 */
-	return port->id == 1;
-}
-
 static void airoha_set_macaddr(struct airoha_gdm_port *port, const u8 *addr)
 {
 	struct airoha_eth *eth = port->qdma->eth;
@@ -1124,7 +1115,7 @@ static int airoha_qdma_init_hfwd_queues(struct airoha_qdma *qdma)
 			LMGR_INIT_START | LMGR_SRAM_MODE_MASK |
 			HW_FWD_DESC_NUM_MASK,
 			FIELD_PREP(HW_FWD_DESC_NUM_MASK, HW_DSCP_NUM) |
-			LMGR_INIT_START);
+			LMGR_INIT_START | LMGR_SRAM_MODE_MASK);
 
 	return read_poll_timeout(airoha_qdma_rr, status,
 				 !(status & LMGR_INIT_START), USEC_PER_MSEC,

drivers/net/ethernet/airoha/airoha_eth.h

@@ -597,6 +597,15 @@ u32 airoha_rmw(void __iomem *base, u32 offset, u32 mask, u32 val);
 #define airoha_qdma_clear(qdma, offset, val)			\
 	airoha_rmw((qdma)->regs, (offset), (val), 0)
 
+static inline bool airhoa_is_lan_gdm_port(struct airoha_gdm_port *port)
+{
+	/* GDM1 port on EN7581 SoC is connected to the lan dsa switch.
+	 * GDM{2,3,4} can be used as wan port connected to an external
+	 * phy module.
+	 */
+	return port->id == 1;
+}
+
 bool airoha_is_valid_gdm_port(struct airoha_eth *eth,
 			      struct airoha_gdm_port *port);
 

drivers/net/ethernet/airoha/airoha_ppe.c

@@ -251,6 +251,12 @@ static int airoha_ppe_foe_entry_prepare(struct airoha_eth *eth,
 		else
 			pse_port = 2; /* uplink relies on GDM2 loopback */
 		val |= FIELD_PREP(AIROHA_FOE_IB2_PSE_PORT, pse_port);
+
+		/* For downlink traffic consume SRAM memory for hw forwarding
+		 * descriptors queue.
+		 */
+		if (airhoa_is_lan_gdm_port(port))
+			val |= AIROHA_FOE_IB2_FAST_PATH;
 	}
 
 	if (is_multicast_ether_addr(data->eth.h_dest))