mirror of
https://github.com/torvalds/linux.git
synced 2024-12-25 04:11:49 +00:00
ceed73a2cf
RmNet driver provides a transport agnostic MAP (multiplexing and aggregation protocol) support in embedded module. Module provides virtual network devices which can be attached to any IP-mode physical device. This will be used to provide all MAP functionality on future hardware in a single consistent location. Signed-off-by: Subash Abhinov Kasiviswanathan <subashab@codeaurora.org> Signed-off-by: David S. Miller <davem@davemloft.net>
83 lines
3.0 KiB
Plaintext
83 lines
3.0 KiB
Plaintext
1. Introduction
|
|
|
|
rmnet driver is used for supporting the Multiplexing and aggregation
|
|
Protocol (MAP). This protocol is used by all recent chipsets using Qualcomm
|
|
Technologies, Inc. modems.
|
|
|
|
This driver can be used to register onto any physical network device in
|
|
IP mode. Physical transports include USB, HSIC, PCIe and IP accelerator.
|
|
|
|
Multiplexing allows for creation of logical netdevices (rmnet devices) to
|
|
handle multiple private data networks (PDN) like a default internet, tethering,
|
|
multimedia messaging service (MMS) or IP media subsystem (IMS). Hardware sends
|
|
packets with MAP headers to rmnet. Based on the multiplexer id, rmnet
|
|
routes to the appropriate PDN after removing the MAP header.
|
|
|
|
Aggregation is required to achieve high data rates. This involves hardware
|
|
sending aggregated bunch of MAP frames. rmnet driver will de-aggregate
|
|
these MAP frames and send them to appropriate PDN's.
|
|
|
|
2. Packet format
|
|
|
|
a. MAP packet (data / control)
|
|
|
|
MAP header has the same endianness of the IP packet.
|
|
|
|
Packet format -
|
|
|
|
Bit 0 1 2-7 8 - 15 16 - 31
|
|
Function Command / Data Reserved Pad Multiplexer ID Payload length
|
|
Bit 32 - x
|
|
Function Raw Bytes
|
|
|
|
Command (1)/ Data (0) bit value is to indicate if the packet is a MAP command
|
|
or data packet. Control packet is used for transport level flow control. Data
|
|
packets are standard IP packets.
|
|
|
|
Reserved bits are usually zeroed out and to be ignored by receiver.
|
|
|
|
Padding is number of bytes to be added for 4 byte alignment if required by
|
|
hardware.
|
|
|
|
Multiplexer ID is to indicate the PDN on which data has to be sent.
|
|
|
|
Payload length includes the padding length but does not include MAP header
|
|
length.
|
|
|
|
b. MAP packet (command specific)
|
|
|
|
Bit 0 1 2-7 8 - 15 16 - 31
|
|
Function Command Reserved Pad Multiplexer ID Payload length
|
|
Bit 32 - 39 40 - 45 46 - 47 48 - 63
|
|
Function Command name Reserved Command Type Reserved
|
|
Bit 64 - 95
|
|
Function Transaction ID
|
|
Bit 96 - 127
|
|
Function Command data
|
|
|
|
Command 1 indicates disabling flow while 2 is enabling flow
|
|
|
|
Command types -
|
|
0 for MAP command request
|
|
1 is to acknowledge the receipt of a command
|
|
2 is for unsupported commands
|
|
3 is for error during processing of commands
|
|
|
|
c. Aggregation
|
|
|
|
Aggregation is multiple MAP packets (can be data or command) delivered to
|
|
rmnet in a single linear skb. rmnet will process the individual
|
|
packets and either ACK the MAP command or deliver the IP packet to the
|
|
network stack as needed
|
|
|
|
MAP header|IP Packet|Optional padding|MAP header|IP Packet|Optional padding....
|
|
MAP header|IP Packet|Optional padding|MAP header|Command Packet|Optional pad...
|
|
|
|
3. Userspace configuration
|
|
|
|
rmnet userspace configuration is done through netlink library librmnetctl
|
|
and command line utility rmnetcli. Utility is hosted in codeaurora forum git.
|
|
The driver uses rtnl_link_ops for communication.
|
|
|
|
https://source.codeaurora.org/quic/la/platform/vendor/qcom-opensource/dataservices/tree/rmnetctl
|