net: cdc_mbim: Device Service Stream support (9f651cac) · Commits · 戴 / test

MBIM devices can support up to 256 generic streams called Device Service Streams (DSS). The MBIM spec says The format of the Device Service Stream payload depends on the device service (as identified by the corresponding UUID) that is used when opening the data stream. Example use cases are serial AT command interfaces and NMEA data streams. We cannot make any assumptions about these device services. Adding support for Device Service Stream by extending the MBIM session to VLAN mapping scheme, allocating VLAN IDs 256 to 511 for DSS, using the DSS SessionID as the lower 8bit of the VLAN ID. Using a netdev for DSS keeps the device framing intact and allows userspace to do whatever it want with the streams. For example, exporting an AT command interface using DSS session #0 to a PTY for use with a terminal application like minicom: vconfig add wwan0 256 ip link set dev wwan0 up ip link set dev wwan0.256 up socat INTERFACE:wwan0.256,type=2 PTY:,echo=0,link=/tmp/modem Device configuration must be done using MBIM control commands over the /dev/cdc-wdmx device. The userspace management application should coordinate host VLAN configuration and the device MBIM configuration using the device capabilities to find out if it needs to set up PTY mappings etc. Signed-off-by:

Bjørn Mork <bjorn@mork.no> Signed-off-by:

David S. Miller <davem@davemloft.net>

drivers/net/usb/cdc_mbim.c

+35 −23

Original line number	Diff line number	Diff line
		@@ -149,12 +149,27 @@ static struct sk_buff cdc_mbim_tx_fixup(struct usbnet dev, struct sk_buff *skb
		/* mapping VLANs to MBIM sessions:
		* no tag => IPS session <0>
		* 1 - 255 => IPS session <vlanid>
		* 256 - 4095 => unsupported, drop
		* 256 - 511 => DSS session <vlanid - 256>
		* 512 - 4095 => unsupported, drop
		*/
		vlan_get_tag(skb, &tci);

		switch (tci & 0x0f00) {
		case 0x0000: /* VLAN ID 0 - 255 */
		/* verify that datagram is IPv4 or IPv6 */
		skb_reset_mac_header(skb);
		switch (eth_hdr(skb)->h_proto) {
		case htons(ETH_P_IP):
		case htons(ETH_P_IPV6):
		break;
		default:
		goto error;
		}
		c = (u8 *)&sign;
		c[3] = tci;
		break;
		case 0x0100: /* VLAN ID 256 - 511 */
		sign = cpu_to_le32(USB_CDC_MBIM_NDP16_DSS_SIGN);
		c = (u8 *)&sign;
		c[3] = tci;
		break;
		@@ -163,16 +178,7 @@ static struct sk_buff cdc_mbim_tx_fixup(struct usbnet dev, struct sk_buff *skb
		"unsupported tci=0x%04x\n", tci);
		goto error;
		}

		skb_reset_mac_header(skb);
		switch (eth_hdr(skb)->h_proto) {
		case htons(ETH_P_IP):
		case htons(ETH_P_IPV6):
		skb_pull(skb, ETH_HLEN);
		break;
		default:
		goto error;
		}
		}

		spin_lock_bh(&ctx->mtx);
		@@ -189,9 +195,10 @@ error:

		static struct sk_buff cdc_mbim_process_dgram(struct usbnet dev, u8 *buf, size_t len, u16 tci)
		{
		__be16 proto;
		__be16 proto = htons(ETH_P_802_3);
		struct sk_buff *skb = NULL;

		if (tci < 256) { /* IPS session? */
		if (len < sizeof(struct iphdr))
		goto err;

		@@ -205,6 +212,7 @@ static struct sk_buff cdc_mbim_process_dgram(struct usbnet dev, u8 *buf, size_
		default:
		goto err;
		}
		}

		skb = netdev_alloc_skb_ip_align(dev->net, len + ETH_HLEN);
		if (!skb)
		@@ -259,6 +267,10 @@ next_ndp:
		c = (u8 *)&ndp16->dwSignature;
		tci = c[3];
		break;
		case cpu_to_le32(USB_CDC_MBIM_NDP16_DSS_SIGN):
		c = (u8 *)&ndp16->dwSignature;
		tci = c[3] + 256;
		break;
		default:
		netif_dbg(dev, rx_err, dev->net,
		"unsupported NDP signature <0x%08x>\n",

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