MBIM protocol makes the mhi network interface asymmetric, ingress data
received from MHI is MBIM protocol, possibly containing multiple
aggregated IP packets, while egress data received from network stack is
IP protocol.
This changes allows a 'protocol' to specify its own MRU, that when
specified is used to allocate MHI RX buffers (skb).
For MBIM, Set the default MTU to 1500, which is the usual network MTU
for WWAN IP packets, and MRU to 3.5K (for allocation efficiency),
allowing skb to fit in an usual 4K page (including padding,
skb_shared_info, ...).
Signed-off-by: Loic Poulain <loic.poulain@linaro.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
MBIM has initially been specified by USB-IF for transporting data (IP)
between a modem and a host over USB. However some modern modems also
support MBIM over PCIe (via MHI). In the same way as QMAP(rmnet), it
allows to aggregate IP packets and to perform context multiplexing.
This change adds minimal MBIM data transport support to MHI, allowing
to support MBIM only modems. MBIM being based on USB NCM, it reuses
and copy some helpers/functions from the USB stack (cdc-ncm, cdc-mbim).
Note that is a subset of the CDC-MBIM specification, supporting only
transport of network data (IP), there is no support for DSS. Moreover
the multi-session (for multi-pdn) is not supported in this initial
version, but will be added latter, and aligned with the cdc-mbim
solution (VLAN tags).
This code has been inspired from the mhi_mbim downstream implementation
(Carl Yin <carl.yin@quectel.com>).
Signed-off-by: Loic Poulain <loic.poulain@linaro.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
This can be used by proto when packet len is incorrect.
Signed-off-by: Loic Poulain <loic.poulain@linaro.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
Move mhi-net shared structures to mhi header, that will be used by
upcoming proto(s).
Signed-off-by: Loic Poulain <loic.poulain@linaro.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
Loic Poulain