`DMA`

DMA Facilities Interface

Work with DMA-able host memory and DMA descriptors: allocate and free buffers, translate between CPU and bus addresses, fill or edit buffers, and build or dump DMA vectors (DVs) and descriptors (DCBs). It is a tool for driver debugging; it does not start DMA transfers by itself. Sub-command keywords must be typed in full (any case).

Results are stored in shell variables ($dma_laddr, $dma_paddr, $dma_size, $dma_count, $dma_bytes, $dma_shorts, $dma_words, $dma_dv_laddr, $dma_dcb_laddr, $dma_dcb_count, $dma_dcb_size) and used as defaults by later sub-commands.

Warning

Addresses are pointers inside the syncd process. fill, load, edit, free, dvfree and dcbdump on an address that was not allocated with dma alloc/dma dvalloc can corrupt syncd’s packet buffers or crash it.

Unvalidated — Allocate 64 words, show the bus address, free them

drivshell> dma alloc w 64 test
drivshell> dma l2p
drivshell> dma free

DMA alloc [b|h|w] <count> [<name>]

Allocate DMA-able memory of <count> bytes, half-words or words and print its address (Allocated <n> bytes of DMA-able memory at address <p>). Sets $dma_laddr and the size variables.

Unvalidated

drivshell> dma alloc b 256

DMA fill [b|h|w] <laddr> <count> <value>

Fill a buffer with a value. dma load <laddr> <hex data> copies hex bytes into it; dma edit edits it interactively; flush/inval maintain the CPU cache for a region.

Unvalidated

drivshell> dma fill w $dma_laddr 64 0

DMA dvalloc [r|t] <dcb_count>

Allocate an RX (r) or TX (t) DMA vector with <dcb_count> descriptors. dma addrx <dv_laddr> <buf_laddr> <bytes> adds an RX descriptor, dma dcbdump [r|t] <dcb_laddr> decodes a descriptor and dma dvfree <dv_laddr> frees the vector.

Unvalidated

drivshell> dma dvalloc r 4
drivshell> dma dcbdump r $dma_dcb_laddr
drivshell> dma dvfree $dma_dv_laddr

Built-in help

Usages:

      dma alloc [b|h|w] <count> [name]
                Allocate DMA-able memory (you can add region name)
      dma free  [<laddr>]
                Free DMA-able memory
      dma l2p   [<laddr>]
                Convert logical (CPU) address into a physical (bus) address
      dma p2l   [<paddr>]
                Convert physical (bus) address into a logical (CPU) address
      dma flush [b|h|w] [<laddr> [<count>]]
                Flush the cache corresponding to the DMA-able memory region
      dma inval [b|h|w] [<laddr> [<count>]]
                Invalidate the cache corresponding to the DMA-able memory region
      dma load  <laddr> <hex data>
                Fill DMA-able memory with provided hex data
      dma fill  [b|h|w] <laddr> <count> <value>
                Fill DMA-able memory with provided value
      dma edit  [b|h|w] [<laddr>]
                Interactive memory editing
      dma dvalloc [r|t] <dcb_count>
                Allocate a DMA Vector (DV) with dcb_count DCBs
      dma dvfree dv_addr
                Free a DV together with the allocated DCBs
      dma addrx <dv_laddr> <buf_laddr> <bytes>
                Add an RX DCB to the DV chain
      dma dcbdump [r|t] $dcb_laddr
                Dump the memory as a DCB

Note:
    The following variables contain the results of the subcommands and
    be used as default arguments:
        $dma_laddr     -- the logical  address of DMA-able memory
        $dma_paddr     -- the physical address of DMA-able memory
        $dma_size     -- the size of the element (b, h, or w)
        $dma_count     -- the number of elements (bytes, shorts, words)
        $dma_bytes     -- number of bytes in the allocated region
        $dma_shorts     -- number of shorts in the allocated region
        $dma_words     -- number of words in the allocated region
        $dma_dv_laddr     -- the logical address of the allocated
                    DMA vector (DV)
        $dma_dcb_laddr     -- the logical address of allocated DCB chain
        $dma_dcb_count     -- number of DCBs in the allocated chain
        $dma_dcb_size     -- the size of a single DCB in bytes

DMA

`DMA`