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[net-next,v4,1/3] docs: networking: Add documentation for MAPv5

Message ID 1619121731-17782-2-git-send-email-sharathv@codeaurora.org (mailing list archive)
State Superseded
Delegated to: Netdev Maintainers
Headers show
Series net: qualcomm: rmnet: Enable Mapv5 | expand

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Commit Message

Sharath Chandra Vurukala April 22, 2021, 8:02 p.m. UTC 
Adding documentation explaining the new MAPv4/v5 packet formats
and the corresponding checksum offload headers.

Signed-off-by: Sharath Chandra Vurukala <sharathv@codeaurora.org>
---
 .../device_drivers/cellular/qualcomm/rmnet.rst     | 126 +++++++++++++++++++--
 1 file changed, 114 insertions(+), 12 deletions(-)

Comments

Alex Elder April 23, 2021, 12:32 p.m. UTC | #1 
On 4/22/21 3:02 PM, Sharath Chandra Vurukala wrote:
> Adding documentation explaining the new MAPv4/v5 packet formats
> and the corresponding checksum offload headers.
> 
> Signed-off-by: Sharath Chandra Vurukala <sharathv@codeaurora.org>


Thank you for updating this document, and in particular
for adding documentation for QMAPv4.

While I might suggest minor changes here or there to
wording, I think the document does a good enough job
of describing RMNet data structures.

My main interest right now is enabling inline checksum
offload functionality, so for now I'm content to just
acknowledge this patch.

Acked-by: Alex Elder <elder@linaro.org>

> ---
>   .../device_drivers/cellular/qualcomm/rmnet.rst     | 126 +++++++++++++++++++--
>   1 file changed, 114 insertions(+), 12 deletions(-)
> 
> diff --git a/Documentation/networking/device_drivers/cellular/qualcomm/rmnet.rst b/Documentation/networking/device_drivers/cellular/qualcomm/rmnet.rst
> index 70643b5..4118384 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
>
diff mbox series

Patch

diff --git a/Documentation/networking/device_drivers/cellular/qualcomm/rmnet.rst b/Documentation/networking/device_drivers/cellular/qualcomm/rmnet.rst
index 70643b5..4118384 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