Corelink DMA Engines

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Revision as of 04:37, 29 June 2018 by Unknown (talk | contribs) (→‎CDMA Peripheral IDs: 0x14 is related to y2r2)
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XDMA cannot access the ARM9 bootrom at all.


Size of struct is 24 bytes.

struct DmaConfig {
    sint8_t channel_sel; // @0 Selects which DMA channel to use: 0-7, -1 = don't care.
    uint8_t endian_swap_size; // @1 Accepted values: 0=none, 2=16bit, 4=32bit, 8=64bit.
    uint8_t flags; // @2 bit0: SRC_IS_PERIPHERAL, bit1: DST_IS_PERIPHERAL, bit2: SHALL_BLOCK, bit3: KEEP_ALIVE, bit6: SRC_IS_RAM, bit7: DST_IS_RAM
    uint8_t padding;
    DmaSubConfig dst_cfg;
    DmaSubConfig src_cfg;
struct DmaSubConfig {
    sint8_t peripheral_id; // @0 If not *_IS_RAM set, this must be < 0x1E.
    uint8_t allowed_burst_sizes; // @1 Accepted values: 4, 8, 4|8 = 12, 1|2|4|8 = 15 
    sint16_t gather_granule_size; // @2
    sint16_t gather_stride; // @4 Has to be >= 0, must not be 0 if peripheral_id == 0xFF.
    sint16_t scatter_granule_size; // @6
    sint16_t scatter_stride; // @8 Can be negative.

If SRC_IS_PERIPHERAL/SRC_IS_PERIPHERAL is set in the flags field, the configuration for src/dst is loaded from src_cfg/dst_cfg respectively and the transfer will be done from/to a fixed address. If the *_IS_RAM flag is set same thing goes, except byte0 of each cfg is forced to 0xFF (RAM) and the transfer will be done from/to an incrementing address. *_IS_RAM has priority over _IS_PERIPHERAL.

If neither *_IS_PERIPHERAL or *_IS_RAM is set, default configuration is loaded:

.peripheral_id = 0xFF,
.allowed_burst_sizes = 1 | 2 | 4 | 8,
.gather_granule_size = 0x80,
.gather_stride = 0,
.scatter_granule_size = 0x80,
.scatter_stride = 0,

If SHALL_BLOCK is set, the thread will sleep until the DMA engine is ready. If not set, the SVC will return 0xD04007F0 if the DMA channel is busy.

The generated bytecode starts with a FLUSHP on the peripheral_ids for src/dst (if specified). After that, it always moves 0 into DAR. Then it moves the src/dst addresses into SAR/DAR respectively...

CDMA Peripheral IDs

ID Module Description
0x2 camera (cam) Camera Port 1
0x3 camera (cam) Camera Port 2
0x4 nwm ?
0x5 nwm ?
0x6 camera (y2r) SetSendingY
0x7 camera (y2r) SetSendingU
0x8 camera (y2r) SetSendingV
0x9 camera (y2r) SetSendingYUYV
0xA camera (y2r) SetReceiving
0xB fs HASH
0xD TwlBg LGYFB0/1
0xE TwlBg LGYFB0/1
0x12 mvd Related to y2r2
0x13 mvd Related to y2r2
0x14 mvd Related to y2r2
0x15 mvd Related to y2r2
0x16 mvd Related to y2r2
0x17 mvd Related to l2b
0x18 mvd Related to l2b
0x19 mvd Related to l2b
0x1A mvd Related to l2b

XDMA Peripheral IDs

ID Module Description
0 Process9 CTRCARD
7 Process9 SHA