From: Sharath Chandra Vurukala Date: Tue, 1 Jun 2021 19:28:34 +0000 (+0530) Subject: docs: networking: Add documentation for MAPv5 X-Git-Tag: microblaze-v5.15~120^2~374^2~2 X-Git-Url: http://git.monstr.eu/?a=commitdiff_plain;h=710b797cf61b318995db6d31767a532162db113d;p=linux-2.6-microblaze.git docs: networking: Add documentation for MAPv5 Adding documentation explaining the new MAPv4/v5 packet formats and the corresponding checksum offload headers. Signed-off-by: Sharath Chandra Vurukala Signed-off-by: David S. Miller --- diff --git a/Documentation/networking/device_drivers/cellular/qualcomm/rmnet.rst b/Documentation/networking/device_drivers/cellular/qualcomm/rmnet.rst index 70643b58de05..4118384cf8eb 100644 --- a/Documentation/networking/device_drivers/cellular/qualcomm/rmnet.rst +++ b/Documentation/networking/device_drivers/cellular/qualcomm/rmnet.rst @@ -27,34 +27,136 @@ these MAP frames and send them to appropriate PDN's. 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:: - 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 - 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. 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. -Reserved bits are usually zeroed out and to be ignored by receiver. +Reserved bits must be zero when sent and ignored when received. -Padding is number of bytes to be added for 4 byte alignment if required by -hardware. +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 (command specific):: +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 +or data packet. Command packet is used for transport level flow control. Data +packets are standard IP packets. + +Next header is used to indicate the presence of another header, currently is +limited to checksum header. + +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. + +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 Bit 32 - 39 40 - 45 46 - 47 48 - 63 Function Command name Reserved Command Type Reserved @@ -74,7 +176,7 @@ Command types 3 is for error during processing of commands = ========================================== -c. Aggregation +f. Aggregation Aggregation is multiple MAP packets (can be data or command) delivered to rmnet in a single linear skb. rmnet will process the individual