Commit 710b797c authored by Sharath Chandra Vurukala's avatar Sharath Chandra Vurukala Committed by David S. Miller

docs: networking: Add documentation for MAPv5

Adding documentation explaining the new MAPv4/v5 packet formats
and the corresponding checksum offload headers.
Signed-off-by: default avatarSharath Chandra Vurukala <sharathv@codeaurora.org>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent e0ae757c
...@@ -27,32 +27,134 @@ these MAP frames and send them to appropriate PDN's. ...@@ -27,32 +27,134 @@ these MAP frames and send them to appropriate PDN's.
2. Packet format 2. Packet format
================ ================
a. MAP packet (data / control) a. MAP packet v1 (data / control)
MAP header has the same endianness of the IP packet. MAP header fields are in big endian format.
Packet format:: Packet format::
Bit 0 1 2-7 8 - 15 16 - 31 Bit 0 1 2-7 8-15 16-31
Function Command / Data Reserved Pad Multiplexer ID Payload length Function Command / Data Reserved Pad Multiplexer ID Payload length
Bit 32 - x
Function Raw Bytes 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. Command packet is used for transport level flow control. Data
packets are standard IP packets.
Reserved bits must be zero when sent and ignored when received.
Padding is the number of bytes to be appended to the payload to
ensure 4 byte alignment.
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 v4 (data / control)
MAP header fields are in big endian format.
Packet format::
Bit 0 1 2-7 8-15 16-31
Function Command / Data Reserved Pad Multiplexer ID Payload length
Bit 32-(x-33) (x-32)-x
Function Raw bytes Checksum offload header
Command (1)/ Data (0) bit value is to indicate if the packet is a MAP command
or data packet. Command packet is used for transport level flow control. Data
packets are standard IP packets.
Reserved bits must be zero when sent and ignored when received.
Padding is the number of bytes to be appended to the payload to
ensure 4 byte alignment.
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.
Checksum offload header, has the information about the checksum processing done
by the hardware.Checksum offload header fields are in big endian format.
Packet format::
Bit 0-14 15 16-31
Function Reserved Valid Checksum start offset
Bit 31-47 48-64
Function Checksum length Checksum value
Reserved bits must be zero when sent and ignored when received.
Valid bit indicates whether the partial checksum is calculated and is valid.
Set to 1, if its is valid. Set to 0 otherwise.
Padding is the number of bytes to be appended to the payload to
ensure 4 byte alignment.
Checksum start offset, Indicates the offset in bytes from the beginning of the
IP header, from which modem computed checksum.
Checksum length is the Length in bytes starting from CKSUM_START_OFFSET,
over which checksum is computed.
Checksum value, indicates the checksum computed.
c. MAP packet v5 (data / control)
MAP header fields are in big endian format.
Packet format::
Bit 0 1 2-7 8-15 16-31
Function Command / Data Next header 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 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 or data packet. Command packet is used for transport level flow control. Data
packets are standard IP packets. packets are standard IP packets.
Reserved bits are usually zeroed out and to be ignored by receiver. Next header is used to indicate the presence of another header, currently is
limited to checksum header.
Padding is number of bytes to be added for 4 byte alignment if required by Padding is the number of bytes to be appended to the payload to
hardware. ensure 4 byte alignment.
Multiplexer ID is to indicate the PDN on which data has to be sent. 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 Payload length includes the padding length but does not include MAP header
length. length.
b. MAP packet (command specific):: d. Checksum offload header v5
Checksum offload header fields are in big endian format.
Bit 0 - 6 7 8-15 16-31
Function Header Type Next Header Checksum Valid Reserved
Header Type is to indicate the type of header, this usually is set to CHECKSUM
Header types
= ==========================================
0 Reserved
1 Reserved
2 checksum header
Checksum Valid is to indicate whether the header checksum is valid. Value of 1
implies that checksum is calculated on this packet and is valid, value of 0
indicates that the calculated packet checksum is invalid.
Reserved bits must be zero when sent and ignored when received.
e. MAP packet v1/v5 (command specific)::
Bit 0 1 2-7 8 - 15 16 - 31 Bit 0 1 2-7 8 - 15 16 - 31
Function Command Reserved Pad Multiplexer ID Payload length Function Command Reserved Pad Multiplexer ID Payload length
...@@ -74,7 +176,7 @@ Command types ...@@ -74,7 +176,7 @@ Command types
3 is for error during processing of commands 3 is for error during processing of commands
= ========================================== = ==========================================
c. Aggregation f. Aggregation
Aggregation is multiple MAP packets (can be data or command) delivered to Aggregation is multiple MAP packets (can be data or command) delivered to
rmnet in a single linear skb. rmnet will process the individual rmnet in a single linear skb. rmnet will process the individual
......
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