Changes between Version 2 and Version 3 of Component/Vci Chbuf Dma


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Timestamp:
Jan 13, 2015, 11:46:58 AM (9 years ago)
Author:
alain
Comment:

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  • Component/Vci Chbuf Dma

    v2 v3  
    2020This DMA controller implements two mode to scan the SRC and DST chbufs:
    2121 * '''IN_ORDER_FIFO''': Both the source chained buffers and the destination chained buffers are accessed in strict order, as defined by the SRC and DST chbuf descriptors. The access is blocking until the expected buffer is available. If the buffer is not available, the delay before retry is defined by the software addressable register CHBUF_PERIOD. This register must be non zero to activate this mode.
    22  * '''OUT_OF_ORDER''': The arc and DST chbuf descriptors are scanned. The first full SRC buffer found is read, and the first empty DST buffer found is written, with a round robin priority. This mode is activated when the CHBUF_PERIOD value is zero (default value).
     22 * '''OUT_OF_ORDER''': The SRC and DST chbuf descriptors are scanned with a round robin priority. The first full SRC buffer found is read, and the first empty DST buffer found is written. This mode is activated when the CHBUF_PERIOD value is zero (default value).
    2323
    24 This component supports both 32 bits and 64 bits VCI RDATA & WDATA fields.
     24This component supports both 32 bits and 64 bits VCI RDATA & WDATA fields, and supports VCI addresses up to 64 bits.
     25In order to support multiple simultaneous transactions, the channel index is transmited in the VCI TRDID field.   
    2526
    2627The number of channels and the max burst size are constructor parameters:
    2728 * The number of channels (simultaneous transfers) cannot be larger than 8.
    28  * The burst length (in bytes) must be a power of 2 no larger than 64, and is typically equal to the system cache line width.
     29 * The burst length (in bytes) must be a power of 2 no larger than 64, and is typically equal to the system cache line width. If the source and destinat aligned on a burst boundary, the DMA controler split the burst in two VCI transactions.
    2930
    30 Each channel k has 5 memory-mapped registers :
    31  * '''CHBUF_SRC[k]The chbuf descriptor address (CHBUF_DESC), and the number of chained
    32 //  buffers (CHBUF_NBUFS), as well as the elementary buffer size (BUF_SIZE)
    33 //  are software parameters that must be  written in addressable registers
    34 //  when launching a transfer between two chbufs.
    35 //
    36 // 
    37 //  - The elementary buffer size and all buffers base addresses must be multiple
    38 //    of 4 bytes. If the source and destination buffers are not aligned on a burst
    39 //    boundary, the DMA controler split the burst in two VCI transactions.
    40 //
    41 //  In order to support various protection mechanisms, for each channel,
    42 //  the channel addressable registers takes 4K bytes in the address space.
    43 //  Only 8 address bits are decoded .
    44 //  - The 5 bits ADDRESS[4:Ø] define the target register (see chbuf_dma.h)
    45 //  - The 3 bits ADDRESS[14:12] define the selected channel.
    46 //
     31Each channel [k] has 10 memory-mapped 32 bits registers:
     32 * CHBUF_RUN[k]       (write-only) : channel activated when writing a non-zero value
     33 * CHBUF_STATUS[k]    (read-only)  : channel status
     34 * CHBUF_SRC_DESC[k]  (read/write) : SRC chbuf descriptor 32 LSB bits physical address
     35 * CHBUF_DST_DESC[k]  (read/write) : DST chbuf descriptor 32 LSB bits physical address
     36 * CHBUF_SRC_NBUFS[k] (read/write) : SRC chbuf number of buffers
     37 * CHBUF_DST_NBUFS[k] (read/write) : DST chbuf number of buffers,
     38 * CHBUF_BUF_SIZE[k]  (read/write) : buffer size for both source & destination 
     39 * CHBUF_PERIOD[k]    (read/write) : number of cycles between two status polling
     40 * CHBUF_SRC_EXT[k]   (read/write) : SRC chbuf descriptor 32 MSB bits physical address
     41 * CHBUF_DST_EXT[k]   (read/write) : DST chbuf descriptor 32 MSB bits physical address
     42For extensibility issues, you should access the DMA using globally-defined offsets, and you should include file `soclib/chbuf_dma.h` in your software.
     43In order to support various protection mechanisms, for each channel, the channel addressable registers takes 4K bytes in the address space.
     44The following address bits are decoded .
     45 * The 5 bits ADDRESS[4:0] define the target register.
     46 * The 3 bits ADDRESS[14:12] define the selected channel.
    4747
    48 For each channel, the relevant values for the channel status are:
    49  * CHANNEL_IDLE           :    channel not running
    50  * CHANNEL_SRC_DESC_ERROR :    bus error accessing SRC CHBUF descriptor
    51  * CHANNEL_DST_DESC_ERROR :    bus error accessing DST CHBUF descriptor
    52  * CHANNEL_SRC_DATA_ERROR :    bus error accessing SRC CHBUF data
    53  * CHANNEL_DST_DATA_ERROR :    bus error accessing DST CHBUF data
    54  * CHANNEL_BUSY           :    channel running
     48For each channel, the relevant values for the channel status are the following:
     49 || Channel Status         || value ||                                           ||
     50 || CHANNEL_IDLE           || 0     || channel not running                       ||
     51 || CHANNEL_SRC_DESC_ERROR || 1     || bus error accessing SRC CHBUF descriptor  ||
     52 || CHANNEL_DST_DESC_ERROR || 2     || bus error accessing DST CHBUF descriptor  ||
     53 || CHANNEL_SRC_DATA_ERROR || 3     || bus error accessing SRC CHBUF data        ||
     54 || CHANNEL_DST_DATA_ERROR || 4     || bus error accessing DST CHBUF data        ||
     55 || CHANNEL_BUSY           || >4    || channel running                           ||
    5556
    5657There is one private IRQ line for each channel, that is only used for bus error signaling, and is activated when channel[k] enters
    57 n error state. The channel can be reset by writing a nul value in register CHBUF_RUN[k], focing channel[k] to IDLE state.
    58 //
    59 //  In order to support multiple simultaneous transactions, the channel
    60 //  index is transmited in the VCI TRDID field.   
    61 As the !VciDma component, this component  moves data from
    62 a source memory buffer to a destination memory buffer.
    63 It is both a target and an initiator.
    64  * It is addressed as a target to be configured for a transfer.
    65  * It is acting as an initiator to do the transfer.
     58an error state. The channel can be reset by writing a nul value in register CHBUF_RUN[k], focing channel[k] to IDLE state.
    6659
    67 The !VciMultiDma component supports up to 8 simultaneous DMA transfers,
    68 corresponding to 8 independant DMA channels. As there is only one VCI initiator port, the general arbitration policy between the active channels is round-robin.
    69 
    70 The number of channels (CHANNELS) and the burst length (MAX_BURST_LENGTH) are constructor parameters. The burst length parameter must be multiple of 4 bytes.
    71 
    72 This component makes the assumption that the VCI RDATA & WDATA fiels have 32 bits.
    73 The source buffer base address, the destination buffer base address and the buffer length
    74 mus be multiple of 4 bytes. The buffer length is not constrained to be a multiple of
    75 the burst length.
    76 
    77 Each channel has its own set of memory mapped registers, and for each
    78 channel a specific IRQ can be optionally asserted when transfer is completed.
    79 
    80 
    81 
    82  * '''DMA_SRC[k]''' (Read / Write)
    83 It defines the physical address of the source buffer.
    84 
    85  * '''DMA_DST[k]''' (Read / Write)
    86 It defines the physical address of the destination buffer.
    87 
    88  * '''DMA_LEN[k]''' (Read / Write)
    89 A write access defines the length of the transfer (in bytes), and starts the transfer.
    90 A read access returns the DMA channel status. The relevant values for the status are:
    91    || Cnannel Status || Value ||
    92    ||DMA_IDLE        ||  2    ||
    93    ||DMA_SUCCESS     ||  0    ||
    94    ||DMA_READ_ERROR  ||  1    ||
    95    ||DMA_WRITE_ERROR ||  3    ||
    96    ||DMA_BUSY        ||  >3   ||
    97 
    98  * '''DMA_RESET[k]''' (Write-only)
    99 Writing any value into this pseudo-register makes a clean re-initialisation of the DMA coprocessor:
    100 The on-going VCI transaction is completed before the coprocessor returns the IDLE state.
    101 This write access must be used by the software ISR to aknowledge the DMA IRQ.
    102 
    103  * '''DMA_IRQ_DISABLED[k]''' (Read / Write)
    104 A non zero value disables the IRQ line. The RESET value is zero.
    105 
    106 In order to support various protection mechanisms, each channel akes 4K bytes in the address space. The segment size is 32 K bytes, and the segment associated to this peripheral must be aligned on a 32K bytes boundary. Only 8 address bits are decoded :
    107  * The five bits ADDRESS[4:0] define the target register.
    108  * The three bits ADDRESS[14:12] define the channel index.
    109 
    110 For extensibility issues, you should access the DMA using globally-defined offsets, and
    111 you should include file `soclib/dma.h` in your software, it
    112 defines `DMA_SRC`, `DMA_DST`, `DMA_LEN`, `DMA_RESET`, `DMA_IRQ_DISABLED`.
    113 
    114 This hardware component checks for segmentation violation, and can be used
    115 as a default target.
     60This hardware component checks for segmentation violation, and can be used as a default target.
    11661
    11762== 2) Component definition & usage ==