drivers/net/mhi_net.c

Source file repositories/reference/linux-study-clean/drivers/net/mhi_net.c

File Facts

System
Linux kernel
Corpus path
drivers/net/mhi_net.c
Extension
.c
Size
11140 bytes
Lines
414
Domain
Driver Families
Bucket
drivers/net
Inferred role
Driver Families: operation-table or driver-model contract
Status
pattern implementation candidate

Why This File Exists

Repeatable hardware-adapter layer. Deep compatibility for every driver is out of scope; this atlas records patterns, probe lifecycles, bus glue, IRQ/DMA usage, and links back to core abstractions.

Dependency Surface

Detected Declarations

Annotated Snippet

static const struct net_device_ops mhi_netdev_ops = {
	.ndo_open               = mhi_ndo_open,
	.ndo_stop               = mhi_ndo_stop,
	.ndo_start_xmit         = mhi_ndo_xmit,
	.ndo_get_stats64	= mhi_ndo_get_stats64,
};

static void mhi_net_setup(struct net_device *ndev)
{
	ndev->header_ops = NULL;  /* No header */
	ndev->type = ARPHRD_RAWIP;
	ndev->hard_header_len = 0;
	ndev->addr_len = 0;
	ndev->flags = IFF_POINTOPOINT | IFF_NOARP;
	ndev->netdev_ops = &mhi_netdev_ops;
	ndev->mtu = MHI_NET_DEFAULT_MTU;
	ndev->min_mtu = MHI_NET_MIN_MTU;
	ndev->max_mtu = MHI_NET_MAX_MTU;
	ndev->tx_queue_len = 1000;
}

static struct sk_buff *mhi_net_skb_agg(struct mhi_net_dev *mhi_netdev,
				       struct sk_buff *skb)
{
	struct sk_buff *head = mhi_netdev->skbagg_head;
	struct sk_buff *tail = mhi_netdev->skbagg_tail;

	/* This is non-paged skb chaining using frag_list */
	if (!head) {
		mhi_netdev->skbagg_head = skb;
		return skb;
	}

	if (!skb_shinfo(head)->frag_list)
		skb_shinfo(head)->frag_list = skb;
	else
		tail->next = skb;

	head->len += skb->len;
	head->data_len += skb->len;
	head->truesize += skb->truesize;

	mhi_netdev->skbagg_tail = skb;

	return mhi_netdev->skbagg_head;
}

static void mhi_net_dl_callback(struct mhi_device *mhi_dev,
				struct mhi_result *mhi_res)
{
	struct mhi_net_dev *mhi_netdev = dev_get_drvdata(&mhi_dev->dev);
	struct sk_buff *skb = mhi_res->buf_addr;
	int free_desc_count;

	free_desc_count = mhi_get_free_desc_count(mhi_dev, DMA_FROM_DEVICE);

	if (unlikely(mhi_res->transaction_status)) {
		switch (mhi_res->transaction_status) {
		case -EOVERFLOW:
			/* Packet can not fit in one MHI buffer and has been
			 * split over multiple MHI transfers, do re-aggregation.
			 * That usually means the device side MTU is larger than
			 * the host side MTU/MRU. Since this is not optimal,
			 * print a warning (once).
			 */
			netdev_warn_once(mhi_netdev->ndev,
					 "Fragmented packets received, fix MTU?\n");
			skb_put(skb, mhi_res->bytes_xferd);
			mhi_net_skb_agg(mhi_netdev, skb);
			break;
		case -ENOTCONN:
			/* MHI layer stopping/resetting the DL channel */
			dev_kfree_skb_any(skb);
			return;
		default:
			/* Unknown error, simply drop */
			dev_kfree_skb_any(skb);
			u64_stats_update_begin(&mhi_netdev->stats.rx_syncp);
			u64_stats_inc(&mhi_netdev->stats.rx_errors);
			u64_stats_update_end(&mhi_netdev->stats.rx_syncp);
		}
	} else {
		skb_put(skb, mhi_res->bytes_xferd);

		if (mhi_netdev->skbagg_head) {
			/* Aggregate the final fragment */
			skb = mhi_net_skb_agg(mhi_netdev, skb);
			mhi_netdev->skbagg_head = NULL;
		}

Annotation

Implementation Notes