Decoupled locking DMA architecture

1. A system comprising:

a solid state drive (SSD) controller configured to manage flash memory, the SSD controller including:

a read direct memory access (DMA) controller coupled between a first buffer memory and a function unit, the first buffer memory configured to receive data from a host device;

a write DMA controller coupled between the function unit and a second buffer memory, the second buffer memory configured to provide data to the flash memory;

the read DMA controller configured to send to the function unit a header based on a read DMA command followed by data read from the first buffer memory based on the read DMA command, the data read from the first buffer memory being data received from the host device for storage to the flash memory, the header comprising function unit control information that controls the operation of the function unit and a length field specifying a length of the data read from the first buffer memory and sent to the function unit;

the function unit configured to process the header to determine a cryptographic key indicated by the function unit control information of a plurality of cryptographic keys and to perform a cryptographic transform of the data read from the first buffer memory using the cryptographic key indicated by the function unit control information, the cryptographic transform further compressing the data read from the first buffer memory for storage to the flash memory; and

the write DMA controller configured to write the transformed data from the function unit into the second buffer memory.

2. The system of claim 1 , wherein the transformed data from the function unit has a different length than the data read from the first buffer memory.

3. The system of claim 2 , wherein the function unit is further operable to send a modified header to the write DMA controller, the modified header having the length field specifying a length of the transformed data.

4. The system of claim 3 , wherein the write DMA controller is configured to write an amount of data into the second buffer memory corresponding to the length specified by the length field of the modified header.

5. The system of claim 1 , wherein the write DMA controller writes the transformed data in accordance with a write DMA command associated with an operation tag.

6. The system of claim 5 , wherein the operation tag associated with the write DMA command is also associated with the read DMA command.

7. The system of claim 5 , wherein the operation tag associated with the write DMA command is different than an operation tag associated with the read DMA command.

8. The system of claim 6 , wherein the read DMA controller and the write DMA controller are configured to be programmed with the read DMA command and the write DMA command at different times and by different software agents.

9. The system of claim 8 , wherein the read of the data read from the first buffer memory, the transformation of the data transformed by the function unit, and write of the data written to the second buffer memory, are decoupled sub-operations of a same DMA operation.

10. The system of claim 9 , wherein the data read from the first buffer memory, the data transformed by the function unit, and data written to the second buffer memory, selectively according to the data read exceeding a data frame size, are each decomposed into a plurality of data frames that share a same operation tag and are different portions of the same DMA operation.

11. The system of claim 10 , wherein the plurality of data frames sharing the same operation tag are enabled to be processed out-of-order.

12. A method comprising:

reading data from a first buffer memory by a read DMA controller of a solid state drive (SSD) controller configured to manage flash memory based on with a read DMA command, the first buffer memory configured to receive data from a host device;

sending to a function unit of the SSD controller, based on the read DMA command, a header followed by the data, the header comprising function unit control information that controls the operation of the function unit;

processing, by the function unit, the header to determine a cryptographic key indicated by the function unit control information of a plurality of cryptographic keys;

cryptographically transforming the data, by the function unit, using the cryptographic key indicated by the function unit control information comprised in the header, the cryptographic transforming further compressing the data read from the first buffer memory for storage to the flash memory; and

writing the transformed data from the function unit into a second buffer memory by a write DMA controller based on a write DMA command, the second buffer memory configured to provide data to the flash memory.

13. The method of claim 12 , further comprising:

programming the read DMA command independently of programming the write DMA command.

14. The method of claim 12 , further comprising:

associating the read DMA command with a source operation tag;

associating the write DMA command with a receive operation tag; and

wherein the source operation tag and the receive operation tag are different.

15. The method of claim 12 , wherein the read DMA command is associated with a source operation tag, the write DMA command is associated with a receive operation tag, and

the source operation tag and the receive operation tag are identical.

16. The method of claim 12 , further comprising:

respectively performing the reading, sending, transforming, and writing in data frame sized units as different portions of a same DMA operation.

17. The method of claim 16 , further comprising:

processing out-of-order data frame sized units of the same DMA operation.

18. The method of claim 16 , wherein data frame sized units of the same DMA operation all share the same operation tag.

19. The method of claim 12 , wherein the transformed data from the function unit has a different length than the data read from the first buffer memory.

20. An apparatus comprising:

a solid state drive (SSD) controller configured to manage flash memory, the SSD controller including:

a read direct memory access (DMA) controller of the SSD controller coupled between a first buffer memory and a function unit, the first buffer memory configured to receive data from a host device;

a write DMA controller of the SSD controller coupled between the function unit and a second buffer memory, the second buffer memory configured to provide data to the flash memory;

the read DMA controller configured to send to the function unit a header based on a read DMA command followed by data read from the first buffer memory based on the read DMA command, the header comprising function unit control information that controls the operation of the function unit and a length field specifying a length of the data read from the first buffer memory and sent to the function unit;

the function unit configured to perform a cryptographic transform of the data read from the first buffer memory using a cryptographic key indicated by the function unit control information of a plurality of cryptographic keys, the cryptographic transform further compressing the data read from the first buffer memory for storage to the flash memory; and

the write DMA controller configured to write the transformed data from the function unit into the second buffer memory.