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BDMA API

REVISION HISTORY

Revision No.
Description
 Date
1.0
  • Initial release
    		•  11/18/2024
    1.1
  • update template
    		•  11/25/2025

    1. Overview

    Byte-aligned data transfer DMA engine (byte-aligned data transfer direct memory access controller), referred to as BDMA, is mainly used for high-speed data transmission between peripherals and memory, and between memory and memory, and does not require CPU participation.

    This article mainly introduces the operation of BDMA for data transmission under Rtos and Linux systems.

    2. Hardware functions

    • Memory data transfer (mem copy)

    • Memory data filling (mem pattern fill)

    • Memory data search (mem pattern search)

    • Memory data crc calculation (mem crc)

    • The clock is the same frequency as the MIU clock

    The number of BDMA supported by different chips is as follows

    | **chipname** | **mspi number** |
| ------------- | --------------- |
| iford | 3 |
| souffle | 3 |
| ifado | 2 |
| pcupid | 3 |
| ibopper | 2 |
| ifackel | 2 |

    3. Hardware connection diagram

    4. Rtos usage reference

    4.1. Rtos Config configuration

    Rtos uses BDMA, which requires configuration:

    CONFIG_BDMA_SUPPORT=y

    Enter the rtos/proj directory,make menuconfig select config as follows:

    BSP Driver Options  --->
    [*] Support BDMA driver

    4.2. Rtos SYS configuration

    4.2.1. bdma node configuration

    <bdma0>
    [camclk_u16] CAMCLK_VOID;
    [interrupts_u8] INT_IRQ_BDMA;
    [regs_u32] 0x1F200400;
    Attribute Description Remark
    camclk_u16 Used to specify the clock source of BDMA No need to modify
    interrupts_u8 Used to specify the interrupt number of BDMA No need to modify
    regs_u32 Used to specify the address of the BDMA register bank No need to modify

    5. Linux usage reference

    5.1. Linux Config configuration

    Linux uses BDMA, which requires configuration:

    CONFIG_SSTAR_BDMA=y

    Enter the kernel directory,make menuconfig select config as follows:

    Device Drivers  --->
    [*] Sstar SoC platform drivers  --->
        [*]   Sstar BDMA

    5.2. dtsi node description

    bdma0 {
    compatible = "sstar,bdma0";
    interrupts = <GIC_SPI INT_IRQ_BDMA IRQ_TYPE_LEVEL_HIGH>;
    reg = <0x1F200400 0x80>;
    clocks = <&xtal>;
    status = "ok";
};

    The properties supported for configuration in the master driver are as follows:

    Property Description Remark
    compatible Used to match the driver for driver registration, must be consistent with the code Modification prohibited
    reg Used to specify the address of the BDMA register bank No modification required
    interrupts Used to specify the hardware interrupt number and properties used No modification required
    clocks Used to specify the clock source used No modification required
    status Used to select whether to enable the BDMA driver Can be modified as needed

    6. API reference

    The API in drv_bdma.h is used the same in Rtos and Linux.

    Linux path: drivers/sstar_common/include/drv_bdma.h

    Rtos path: proj/sc/driver/sysdriver_common/include/drv_bdma.h

    API name Function
    drv_bdma_initialize Initialize the channel corresponding to BDMA
    drv_bdma_uninitialize Uninitialize BDMA channel
    drv_bdma_transfer BDMA function operation

    6.1. drv_bdma_initialize

    • Function

      Initialize BDMA channel

    • Syntax

      bdma_err drv_bdma_initialize(u8 channel);

    • Parameters

      Parameter name Description Input/Output
      channel Channel selection Input

    • Return value

      • 0: Success.

      • Non-0: Failure.

    • Dependencies

      • Header file: drv_bdma.h

    6.2. drv_bdma_uninitialize

    • Function

      Uninitialize BDMA channel

    • Syntax

      bdma_err drv_bdma_uninitialize(u8 channel);

    • Parameters

      Parameter name Description Input/Output
      channel Channel selection Input

    • Return value

      • 0: Success.

      • Non-0: Failure.

    • Dependencies

      • Header file: drv_bdma.h

    6.3. drv_bdma_transfer

    • Function

      Run BDMA function.

    • Syntax

      bdma_err drv_bdma_transfer(u8 channel, bdma_param *param);

    • Parameters

      Parameter name Description Input/Output
      channel Channel selection Input
      param Transmission configuration parameters Input

    • Return value

      • 0: Success.

      • Non-0: Failure.

    • Dependencies

      • Header file: drv_bdma.h

    • Notes

      • The corresponding channel must be initialized first.

    7. Data structure description

    The relevant data structure is defined as follows.

    Data type Definition
    bdma_param Function-related configuration
    bdma_line_offset Line offset configuration
    bdma_crc CRC32 configuration
    bdma_search Memory data search configuration

    7.1. bdma_param

    • Description

      Data structure related to function configuration.

    • Definition

      typedef struct
{
    u8                bIntMode;
    u8                bEnLineOfst;
    bdma_src_select   eSrcSel;
    bdma_dst_select   eDstSel;
    bdma_data_width   eSrcDataWidth;
    bdma_data_width   eDstDataWidth;
    bdma_addr_mode    eDstAddrMode;
    ss_miu_addr_t     pSrcAddr;
    ss_miu_addr_t     pDstAddr;
    u32               u32TxCount;
    u32               u32Pattern;
    bdma_line_offset *pstLineOfst;
    bdma_crc *        pstCrcst;
    bdma_search *     pstSearchst;
    bdma_callback     pfTxCbFunc;
    void *            pTxCbParm;
} bdma_param;

    • Members

      Member Name Description
      bIntMode Interrupt enable
      bEnLineOfst Configure transmission Width enable
      eSrcSel Source device selection
      eDstSel Target device selection
      eSrcDataWidth Source device transfer width setting
      eDstDataWidth Target device transfer width setting
      eDstAddrMode Target device data entry mode
      pSrcAddr Source device address
      pDstAddr Target device address
      u32TxCount Data transfer size
      u32Pattern Memory data search for specified data
      pstLineOfst Line offset function configuration
      pstCrcst CRC calculation function configuration
      bdma_search Memory search Function configuration
      bdma_callback Interrupt callback function
      pTxCbParm Interrupt callback pointer, private pointer

    7.2. bdma_line_offset

    • Description

      Line offset function configuration.

    • Definition

      typedef struct
{
    u32 u32SrcWidth;
    u32 u32SrcOffset;
    u32 u32DstWidth;
    u32 u32DstOffset;
} bdma_line_offset;

    • Members

      member name description
      u32SrcWidth Source device width
      u32SrcOffset Source device valid data width
      u32DstWidth Destination device width
      u32DstOffset Target device valid data width

    7.3. bdma_crc

    • Description

      The configuration of the crc function.

    • Definition

      typedef struct
{
    u8  reflection;
    u32 polynomial;
    u32 seedvalue;
} bdma_crc;

    • Members

      member name description
      reflection Byte reversal configuration
      polynomial Calculate polynomial
      seedvalue Initial value, calculated as crc value

    • Description

      the memory data search settings.

    • Definition

      typedef struct
{
    u8  antimatch;
    u8  mobf;
    u32 patternmask;
    u32 mobfkey;
    u32 patternaddr;
} bdma_search;

    • Members

      member name description
      antimatch reverse match enable
      mobf MOBF mode enable
      patternmask Search target position
      mobfkey MOBF mode target value
      patternaddr Returned search target address

    8. Test case description

    1. Linux reference: drivers/sstar_common/bdma/ut/lnx/bdma_ut.c

    2. Rtos reference: proj/sc/driver/sysdriver_common/bdma/ut/lnx/bdma_ut.c

    9. FAQ

    9.1 No data at the target address after memory data is moved

    1. Use the CamOsMemFlush() interface to flush the source and target addresses before and after data movement.