eth: fbnic: Add basic Rx handling

Handle Rx packets with basic csum and Rx hash offloads.

NIC writes back to the completion ring a head buffer descriptor
(data buffer allocated from header pages), variable number of payload
descriptors (data buffers in payload pages), an optional metadata
descriptor (type 2) and finally the primary metadata descriptor
(type 3).

This format makes scatter support fairly easy - start gathering
the pages when we see head page, gather until we see the primary
metadata descriptor, do the processing. Use XDP infra to collect
the packet fragments as we traverse the descriptors. XDP itself
is not supported yet, but it will be soon.

Signed-off-by: Alexander Duyck <alexanderduyck@fb.com>
Link: https://patch.msgid.link/172079942839.1778861.10509071985738726125.stgit@ahduyck-xeon-server.home.arpa
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

Author: ahduyck

drivers/net/ethernet/meta/fbnic/fbnic_csr.h

@@ -121,6 +121,69 @@ enum {
 #define FBNIC_BD_PAGE_ID_MASK \
 	(FBNIC_BD_DESC_ID_MASK & ~FBNIC_BD_FRAG_ID_MASK)
 
+/* Rx Completion Queue Descriptors */
+#define FBNIC_RCD_TYPE_MASK			DESC_GENMASK(62, 61)
+enum {
+	FBNIC_RCD_TYPE_HDR_AL	= 0,
+	FBNIC_RCD_TYPE_PAY_AL	= 1,
+	FBNIC_RCD_TYPE_OPT_META	= 2,
+	FBNIC_RCD_TYPE_META	= 3,
+};
+
+#define FBNIC_RCD_DONE				DESC_BIT(63)
+
+/* Address/Length Completion Descriptors */
+#define FBNIC_RCD_AL_BUFF_ID_MASK		DESC_GENMASK(15, 0)
+#define FBNIC_RCD_AL_BUFF_FRAG_MASK		(FBNIC_BD_FRAG_COUNT - 1)
+#define FBNIC_RCD_AL_BUFF_PAGE_MASK \
+	(FBNIC_RCD_AL_BUFF_ID_MASK & ~FBNIC_RCD_AL_BUFF_FRAG_MASK)
+#define FBNIC_RCD_AL_BUFF_LEN_MASK		DESC_GENMASK(28, 16)
+#define FBNIC_RCD_AL_BUFF_OFF_MASK		DESC_GENMASK(43, 32)
+#define FBNIC_RCD_AL_PAGE_FIN			DESC_BIT(60)
+
+/* Header AL specific values */
+#define FBNIC_RCD_HDR_AL_OVERFLOW		DESC_BIT(53)
+#define FBNIC_RCD_HDR_AL_DMA_HINT_MASK		DESC_GENMASK(59, 54)
+enum {
+	FBNIC_RCD_HDR_AL_DMA_HINT_NONE  = 0,
+	FBNIC_RCD_HDR_AL_DMA_HINT_L2	= 1,
+	FBNIC_RCD_HDR_AL_DMA_HINT_L3	= 2,
+	FBNIC_RCD_HDR_AL_DMA_HINT_L4	= 4,
+};
+
+/* Optional Metadata Completion Descriptors */
+#define FBNIC_RCD_OPT_META_TS_MASK		DESC_GENMASK(39, 0)
+#define FBNIC_RCD_OPT_META_ACTION_MASK		DESC_GENMASK(45, 40)
+#define FBNIC_RCD_OPT_META_ACTION		DESC_BIT(57)
+#define FBNIC_RCD_OPT_META_TS			DESC_BIT(58)
+#define FBNIC_RCD_OPT_META_TYPE_MASK		DESC_GENMASK(60, 59)
+
+/* Metadata Completion Descriptors */
+#define FBNIC_RCD_META_RSS_HASH_MASK		DESC_GENMASK(31, 0)
+#define FBNIC_RCD_META_L2_CSUM_MASK		DESC_GENMASK(47, 32)
+#define FBNIC_RCD_META_L3_TYPE_MASK		DESC_GENMASK(49, 48)
+enum {
+	FBNIC_RCD_META_L3_TYPE_OTHER	= 0,
+	FBNIC_RCD_META_L3_TYPE_IPV4	= 1,
+	FBNIC_RCD_META_L3_TYPE_IPV6	= 2,
+	FBNIC_RCD_META_L3_TYPE_V6V6	= 3,
+};
+
+#define FBNIC_RCD_META_L4_TYPE_MASK		DESC_GENMASK(51, 50)
+enum {
+	FBNIC_RCD_META_L4_TYPE_OTHER	= 0,
+	FBNIC_RCD_META_L4_TYPE_TCP	= 1,
+	FBNIC_RCD_META_L4_TYPE_UDP	= 2,
+};
+
+#define FBNIC_RCD_META_L4_CSUM_UNNECESSARY	DESC_BIT(52)
+#define FBNIC_RCD_META_ERR_MAC_EOP		DESC_BIT(53)
+#define FBNIC_RCD_META_ERR_TRUNCATED_FRAME	DESC_BIT(54)
+#define FBNIC_RCD_META_ERR_PARSER		DESC_BIT(55)
+#define FBNIC_RCD_META_UNCORRECTABLE_ERR_MASK	\
+	(FBNIC_RCD_META_ERR_MAC_EOP | FBNIC_RCD_META_ERR_TRUNCATED_FRAME)
+#define FBNIC_RCD_META_ECN			DESC_BIT(60)
+
 /* Register Definitions
  *
  * The registers are laid as indexes into an le32 array. As such the actual

drivers/net/ethernet/meta/fbnic/fbnic_netdev.c

@@ -171,8 +171,10 @@ struct net_device *fbnic_netdev_alloc(struct fbnic_dev *fbd)
 	fbnic_reset_queues(fbn, default_queues, default_queues);
 
 	netdev->features |=
+		NETIF_F_RXHASH |
 		NETIF_F_SG |
-		NETIF_F_HW_CSUM;
+		NETIF_F_HW_CSUM |
+		NETIF_F_RXCSUM;
 
 	netdev->hw_features |= netdev->features;
 	netdev->vlan_features |= netdev->features;

drivers/net/ethernet/meta/fbnic/fbnic_pci.c

@@ -195,6 +195,9 @@ static void fbnic_service_task(struct work_struct *work)
 
 	fbnic_health_check(fbd);
 
+	if (netif_carrier_ok(fbd->netdev))
+		fbnic_napi_depletion_check(fbd->netdev);
+
 	if (netif_running(fbd->netdev))
 		schedule_delayed_work(&fbd->service_task, HZ);