On Tue, Dec 17, 2024 at 01:25:28PM -0500, admiyo@os.amperecomputing.com wrote:

From: Adam Young <redacted>

Implementation of network driver for
Management Control Transport Protocol(MCTP) over
Platform Communication Channel(PCC)

DMTF DSP:0292
https://www.dmtf.org/sites/default/files/standards/documents/DSP0292_1.0.0WIP50.pdf

MCTP devices are specified by entries in DSDT/SDST and
reference channels specified in the PCCT.

Communication with other devices use the PCC based
doorbell mechanism.

Signed-off-by: Adam Young <redacted>
---
 drivers/net/mctp/Kconfig    |  13 ++
 drivers/net/mctp/Makefile   |   1 +
 drivers/net/mctp/mctp-pcc.c | 320 ++++++++++++++++++++++++++++++++++++
 3 files changed, 334 insertions(+)
 create mode 100644 drivers/net/mctp/mctp-pcc.c

[...]
 

[...]

+static void mctp_pcc_client_rx_callback(struct mbox_client *c, void *buffer)
+{
+	struct mctp_pcc_ndev *mctp_pcc_ndev;
+	struct mctp_pcc_hdr mctp_pcc_hdr;
+	struct pcpu_dstats *dstats;
+	struct mctp_skb_cb *cb;
+	struct sk_buff *skb;
+	void *skb_buf;
+	u32 data_len;
+
+	mctp_pcc_ndev = container_of(c, struct mctp_pcc_ndev, inbox.client);
+	memcpy_fromio(&mctp_pcc_hdr, mctp_pcc_ndev->inbox.chan->shmem,
+		      sizeof(struct mctp_pcc_hdr));
+	data_len = mctp_pcc_hdr.length + MCTP_HEADER_LENGTH;
+	skb = netdev_alloc_skb(mctp_pcc_ndev->mdev.dev, data_len);
+
+	dstats = this_cpu_ptr(mctp_pcc_ndev->mdev.dev->dstats);
+	u64_stats_update_begin(&dstats->syncp);
+	if (data_len > mctp_pcc_ndev->mdev.dev->mtu) {
+		u64_stats_inc(&dstats->rx_drops);
+		u64_stats_inc(&dstats->rx_drops);

Double counting rx_drops ?

+		u64_stats_update_end(&dstats->syncp);
+		return;
+	}
+	if (!skb) {
+		u64_stats_inc(&dstats->rx_drops);
+		u64_stats_update_end(&dstats->syncp);
+		return;
+	}
+	u64_stats_inc(&dstats->rx_packets);
+	u64_stats_add(&dstats->rx_bytes, data_len);
+	u64_stats_update_end(&dstats->syncp);

I suspect what Jeremy meant (but please feel free to correct me if
I'm mistaken, Jeremy) was that you may want to use the helpers in:

include/linux/netdevice.h

e.g. 

  dev_dstats_rx_add(mctp_pcc_ndev->mdev.dev, data_len);
  dev_dstats_rx_dropped(mctp_pcc_ndev->mdev.dev);

etc.

[...]

+
+static netdev_tx_t mctp_pcc_tx(struct sk_buff *skb, struct net_device *ndev)
+{
+	struct mctp_pcc_ndev *mpnd = netdev_priv(ndev);
+	struct mctp_pcc_hdr  *mctp_pcc_header;
+	struct pcpu_dstats *dstats;
+	void __iomem *buffer;
+	unsigned long flags;
+	int len = skb->len;
+
+	dstats = this_cpu_ptr(ndev->dstats);
+	u64_stats_update_begin(&dstats->syncp);
+	u64_stats_inc(&dstats->tx_packets);
+	u64_stats_add(&dstats->tx_bytes, skb->len);
+	u64_stats_update_end(&dstats->syncp);

Likewise, as above with the helpers from include/linux/netdevice.h:

  dev_dstats_tx_add( ... );
  dev_dstats_tx_dropped( ... );

But, I'll let Jeremy weigh-in to make sure I've not misspoken.

[...]

+
+static void  mctp_pcc_setup(struct net_device *ndev)

              ^^  nit: double space ?

[...]

+static acpi_status lookup_pcct_indices(struct acpi_resource *ares,
+				       void *context)
+{
+	struct  mctp_pcc_lookup_context *luc = context;

              ^^ nit: double space?

[...]

+static int mctp_pcc_driver_add(struct acpi_device *acpi_dev)
+{

[...]

+
+	rc =  devm_add_action_or_reset(dev, mctp_cleanup_netdev, ndev);

            ^^ nit: double space