Difference between revisions of "NDMA Registers"

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3DS NDMA has 8 channels. The first 0x100-bytes of this IO mem is mirrored at 0x10002100, repeated every 0x100-bytes until the end of the 0x1000-byte IO mem. NDMA can access the ARM9 bootrom, including the protected part before it is locked out.
+
3DS NDMA has 8 channels. The first 0x100-bytes of this IO mem is mirrored at 0x10002100, repeated every 0x100-bytes until the end of the 0x1000-byte IO mem. NDMA can access the Arm9 bootrom, including the protected part before it is locked out.
  
 
= Registers =
 
= Registers =
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!  Bit
 
!  Bit
 
!  Description
 
!  Description
 +
|-
 +
|  4-0
 +
|  Device to device startup mode
 
|-
 
|-
 
|  11-10
 
|  11-10
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|}
 
|}
  
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== Startup modes (27-24) ==
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== Startup modes (4-0) ==
 
{| class="wikitable" border="1"
 
{| class="wikitable" border="1"
 
!  Value
 
!  Value
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|-
 
|-
 
| 6
 
| 6
−
| MMC1
+
| SDIO1
 
|-
 
|-
 
| 7
 
| 7
−
| MMC2?
+
| SDIO3
 
|-
 
|-
 
| 8
 
| 8
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|-
 
|-
 
| 11
 
| 11
−
| SHA out ([[SHA_Registers#SHA_FIFO|INFIFO]])
+
| SHA out ([[SHA_Registers#SHA_FIFO|INFIFO]], source data readback mode)
 
|-
 
|-
 
| 12
 
| 12
−
| ?
+
| NTRCARD
 
|-
 
|-
 
| 13
 
| 13
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|-
 
|-
 
| 15
 
| 15
−
| MMC1 + AES + SHA combined?
+
| Device to device (subclassed by bits 4-0)
 +
|}
 +
 
 +
== Device to device startup modes (4-0) ==
 +
{| class="wikitable" border="1"
 +
!  Value
 +
!  Description
 +
|-
 +
| 0
 +
| CTRCARD0 -> AES
 +
|-
 +
| 1
 +
| CTRCARD1 -> AES
 +
|-
 +
| 2
 +
| AES -> CTRCARD0
 +
|-
 +
| 3
 +
| AES -> CTRCARD1
 +
|-
 +
| 4
 +
| CTRCARD0 -> SHA
 +
|-
 +
| 5
 +
| CTRCARD1 -> SHA
 +
|-
 +
| 6
 +
| SHA -> CTRCARD0
 +
|-
 +
| 7
 +
| SHA -> CTRCARD1
 +
|-
 +
| 8
 +
| SDIO1 -> AES
 +
|-
 +
| 9
 +
| SDIO3 -> AES
 +
|-
 +
| 10
 +
| AES -> SDIO1
 +
|-
 +
| 11
 +
| AES -> SDIO3
 +
|-
 +
| 12
 +
| SDIO1 -> SHA
 +
|-
 +
| 13
 +
| SDIO3 -> SHA
 +
|-
 +
| 14
 +
| SHA -> SDIO1
 +
|-
 +
| 15
 +
| SHA -> SDIO3
 +
|-
 +
| 16
 +
| AES -> SHA
 +
|-
 +
| 17
 +
| SHA -> AES
 
|}
 
|}
  

Latest revision as of 22:48, 10 November 2021

3DS NDMA has 8 channels. The first 0x100-bytes of this IO mem is mirrored at 0x10002100, repeated every 0x100-bytes until the end of the 0x1000-byte IO mem. NDMA can access the Arm9 bootrom, including the protected part before it is locked out.

Registers[edit]

Old3DS Name Address Width Used by
Yes NDMA_GLOBAL_CNT 0x10002000 4 Boot9, Kernel9
Yes NDMA_SRC_ADDR(n) 0x10002004 + (n*0x1c) 4 Boot9, Kernel9
Yes NDMA_DST_ADDR(n) 0x10002008 + (n*0x1c) 4 Boot9, Kernel9
Yes NDMA_TRANSFER_CNT(n) 0x1000200c + (n*0x1c) 4 Boot9, Kernel9
Yes NDMA_WRITE_CNT(n) 0x10002010 + (n*0x1c) 4 Boot9, Kernel9
Yes NDMA_BLOCK_CNT(n) 0x10002014 + (n*0x1c) 4 Boot9, Kernel9
Yes NDMA_FILL_DATA(n) 0x10002018 + (n*0x1c) 4 Boot9, Kernel9
Yes NDMA_CNT(n) 0x1000201C + (n*0x1c) 4 Boot9, Kernel9

NDMA_GLOBAL_CNT[edit]

Bit Description
0 Global enable?
19-16 Cycle selection.
31 DMA arbitration method. 0=Fixed method, 1=Round robin

NDMA_SRC_ADDR[edit]

Bit Description
31-0 Source data address. Must be multiple of 4.

Like old DMA, NDMA_SRC_ADDR is copied to internal registers when written to.

NDMA_DST_ADDR[edit]

BIT DESCRIPTION
31-0 Destination data address. Must be multiple of 4.

Like old DMA, NDMA_DST_ADDR is copied to internal registers when written to.

NDMA_TRANSFER_CNT[edit]

Bit Description
27-0 Total number of words transferred.

NDMA_WRITE_CNT[edit]

Bit Description
23-0 Number of words to transfer.

NDMA_BLOCK_CNT[edit]

Bit Description
15-0 Interval timer.
17-16 Prescaler. 0=System freq, 1=1/4th freq, 2=1/16th freq, 3=1/64th freq.

NDMA_FILL_DATA[edit]

Bit Description
31-0 Fill data.

NDMA_CNT[edit]

Bit Description
4-0 Device to device startup mode
11-10 Destination address update method. 0=Increment, 1=Decrement, 2=Fixed.
12 Destination address reload flag.
14-13 Source address update method. 0=Increment, 1=Decrement, 2=Fixed, 3=No address (for filling)
15 Source address reload flag.
19-16 Block transfer word count = (1<<x) words.
27-24 Startup mode.
28 Immediate mode.
29 Repeating mode.
30 IRQ enable
31 Enable/busy flag.

Startup modes (4-0)[edit]

Value Description
0 TIMER0
1 TIMER1
2 TIMER2
3 TIMER3
4 CTRCARD0
5 CTRCARD1
6 SDIO1
7 SDIO3
8 AES in (WRFIFO)
9 AES out (RDFIFO)
10 SHA in (INFIFO)
11 SHA out (INFIFO, source data readback mode)
12 NTRCARD
13 ?
14 ?
15 Device to device (subclassed by bits 4-0)

Device to device startup modes (4-0)[edit]

Value Description
0 CTRCARD0 -> AES
1 CTRCARD1 -> AES
2 AES -> CTRCARD0
3 AES -> CTRCARD1
4 CTRCARD0 -> SHA
5 CTRCARD1 -> SHA
6 SHA -> CTRCARD0
7 SHA -> CTRCARD1
8 SDIO1 -> AES
9 SDIO3 -> AES
10 AES -> SDIO1
11 AES -> SDIO3
12 SDIO1 -> SHA
13 SDIO3 -> SHA
14 SHA -> SDIO1
15 SHA -> SDIO3
16 AES -> SHA
17 SHA -> AES

Block transfers[edit]

First, a word is always 32 bits. Second, the block transfer specified in NDMA_CNT is the smallest atom of data that will be transferred in a burst. The bus is monopolized until this block is transferred, without splitting up.

The next block transfer will happen after the specified time in the NDMA_BLOCK_CNT interval timer, until done.

Immediate mode[edit]

Transfers the words specified in NDMA_WRITE_CNT immediately following block transfer rules. NDMA_TRANSFER_CNT and repeating mode are ignored.

Repeating mode[edit]

Transfers the words specified in NDMA_WRITE_CNT following the startup mode event. NDMA_TRANSFER_CNT is ignored.

No immediate and no repeating mode[edit]

Transfers the words specified in NDMA_WRITE_CNT for each startup event, and gets disabled when the total number of words in NDMA_TRANSFER_CNT are transferred.

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