xsc: Add eth reception data path

rx data path:
1. The hardware writes incoming packets into the RQ ring buffer and
generates a event queue entry
2. The event handler function(xsc_eth_completion_event in
xsc_eth_events.c) is triggered, invokes napi_schedule() to schedule
a softirq.
3. The kernel triggers the softirq handler net_rx_action, which calls
the driver's NAPI poll function (xsc_eth_napi_poll in xsc_eth_txrx.c).
The driver retrieves CQEs from the Completion Queue (CQ) via
xsc_poll_rx_cq.
4. xsc_eth_build_rx_skb constructs an sk_buff structure, and submits the
SKB to the kernel network stack via napi_gro_receive
5. The driver recycles the RX buffer and notifies the NIC via
xsc_eth_post_rx_wqes to prepare for new packets.

Co-developed-by: Honggang Wei <weihg@yunsilicon.com>
Signed-off-by: Honggang Wei <weihg@yunsilicon.com>
Co-developed-by: Lei Yan <jacky@yunsilicon.com>
Signed-off-by: Lei Yan <jacky@yunsilicon.com>
Signed-off-by: Xin Tian <tianx@yunsilicon.com>
Signed-off-by: NipaLocal <nipa@local>

Author: tianx666

drivers/net/ethernet/yunsilicon/xsc/net/xsc_eth_common.h

@@ -22,6 +22,8 @@
 #define XSC_SW2HW_RX_PKT_LEN(mtu)	\
 	((mtu) + ETH_HLEN + XSC_ETH_RX_MAX_HEAD_ROOM)
 
+#define XSC_RX_MAX_HEAD			(256)
+
 #define XSC_QPN_SQN_STUB		1025
 #define XSC_QPN_RQN_STUB		1024
 
@@ -186,4 +188,12 @@ union xsc_send_doorbell {
 	u32 send_data;
 };
 
+union xsc_recv_doorbell {
+	struct{
+		s32  next_pid : 13;
+		u32 qp_num : 15;
+	};
+	u32 recv_data;
+};
+
 #endif