Overview

Old3DS	A9/A11	Category	Physaddr	Used by	Comments
Yes	A9	CONFIG Registers	0x10000000	Boot9, Process9
Yes	A9	IRQ Registers	0x10001000	Boot9, Process9, Kernel9	ARM9 Interrupt Masking
Yes	A9	NDMA Registers	0x10002000	Boot9, Process9	DMA Engine
Yes	A9	TIMER Registers	0x10003000	Boot9, Process9
Yes	A9	CTRCARD Registers	0x10004000 / 0x10005000	Process9
Yes	A9	EMMC Registers	0x10006000 / 0x10007000	Boot9, Process9, NewKernel9Loader	0x10007000 is normally not enabled on retail, all-zeros when read.
Yes	A9	PXI Registers	0x10008000	Boot9, Process9
Yes	A9	AES Registers	0x10009000	Boot9, Process9, NewKernel9Loader
Yes	A9	SHA Registers	0x1000A000	Boot9, Process9, NewKernel9Loader
Yes	A9	RSA Registers	0x1000B000	Boot9, Process9
Yes	A9	XDMA Registers	0x1000C000	Boot9, Kernel9	CoreLink™ DMA-330 (single-channel).
Yes	A9	SPICARD Registers	0x1000D800	Process9
Yes	A9	CONFIG Registers	0x10010000	Process9
Yes	A9	PRNG Registers	0x10011000	Boot9, Process9	Used as entropy-source for seeding random number generators.
Yes	A9	OTP Registers	0x10012000	Boot9, Kernel9, NewKernel9Loader	Top secret.
Yes	A9	ARM7 Registers	0x10018000	TwlProcess9	Used to setup the ARM7 core for AGB/TWL
Yes	A11/A9	Debug WIFI SDIO Registers?	0x10100000		An SDIO controller is mapped here, NWM references this controller but doesn't have access to it.
Yes	A11/A9	HASH Registers	0x10101000	Filesystem services
Yes	A11/A9	Y2R Registers	0x10102000	Camera Services	y2r
Yes	A11/A9	CSND Registers / DSP Registers	0x10103000	TwlBg, Codec Services, CSND Services, DSP Services	Sound hardware. For DSP regs, see the "DSi XpertTeak" section in no$gba help.
Yes	A11/A9	LGYFB0	0x10110000	TwlBg	IO registers used to access legacy output framebuffer, as well as configure the upscaling filter.
Yes	A11/A9	LGYFB1	0x10111000	TwlBg	IO registers used to access legacy output framebuffer, as well as configure the upscaling filter.
Yes	A11/A9	Camera Registers	0x10120000	Camera Services
Yes	A11/A9	Camera Registers	0x10121000	Camera Services	Mirror of 0x10120000?
Yes	A11/A9	WIFI Registers	0x10122000	NWM Services	WIFI SDIO bus registers
Yes	A11/A9	?	0x10123000	NWM Services	WIFI?
No	A11/A9	MVD Registers	0x10130000	MVD Services
No	A11/A9	MVD Registers	0x10131000	MVD Services
No	A11/A9	MVD Registers	0x10132000	MVD Services
Yes	A11/A9	PDN Registers	0x10140000	Process9, Boot11, Kernel11, TwlBg, DSP Services, NWM Services, SPI Services	Power management.
Yes	A11/A9	PDN Registers	0x10141000	Process9, Boot11, Kernel11, TwlBg, Codec Services, NWM Services, SPI Services, PDN Services	Power management
Yes	A11/A9	SPI Registers	0x10142000	TwlBg, SPI Services
Yes	A11/A9	SPI Registers	0x10143000	TwlBg, dmnt Module	Debugger related?
Yes	A11/A9	I2C Registers	0x10144000	Boot11, Kernel11, TwlBg, I2C Services
Yes	A11/A9	CODEC Registers	0x10145000	TwlBg, Codec Services
Yes	A11/A9	HID Registers	0x10146000	Boot9, Boot11, Kernel11, TwlBg, HID Services, dlp Services	See PAD.
Yes	A11/A9	GPIO Registers	0x10147000	Boot11, TwlBg, GPIO Services, DSP Services(v0)
Yes	A11/A9	I2C Registers	0x10148000	TwlBg, I2C Services
Yes	A11/A9	SPI Registers	0x10160000	Boot9, TwlBg, SPI Services
Yes	A11/A9	I2C Registers	0x10161000	Boot11, TwlBg, I2C Services	See no$gba help for some clues maybe.
Yes	A11/A9	MIC Registers	0x10162000	MIC Services
Yes	A11/A9	PXI Registers	0x10163000	Boot11, Kernel11, TwlBg, PXI Services
Yes	A11/A9	NTRCARD Registers	0x10164000	Boot9, Process9
Yes	A11/A9	MP Registers	0x10165000	MP Services
Yes	A11/A9	MP Registers	0x10170000	MP Services	NTR WIFI Registers, see GBATek.
Yes	A11/A9	MP Registers	0x10171000	MP Services	NTR WIFI Registers (mirror)
Yes	A11/A9	?	0x10172000	?	NTR WIFI Unused?
Yes	A11/A9	?	0x10173000	?	NTR WIFI Unused?
Yes	A11/A9	MP Registers	0x10174000	MP Services	NTR WIFI RAM
Yes	A11/A9	MP Registers	0x10175000	?	NTR WIFI RAM
Yes	A11/A9	MP Registers	0x10176000	?	NTR WIFI Registers (mirror)
Yes	A11/A9	MP Registers	0x10177000	?	NTR WIFI Registers (mirror)
Yes	A11/A9	MP Registers	0x10178000 - 0x10180000	MP Services	NTR WIFI WS1 Region
Yes	A11	CDMA	0x10200000	Boot11, Kernel11	CoreLink™ DMA-330. Only used by bootrom on New3DS.
Yes	A11	?	0x10201000	TwlBg
Yes	A11	LCD Registers	0x10202000	TwlBg, Kernel11, GSP Services
Yes	A11	DSP Registers	0x10203000	DSP Services
Yes	A11	?	0x10204000
No	A11	CDMA	0x10206000	NewKernel11	CDMA was moved (mirrored?) here on New 3DS. CoreLink™ DMA-330.
No	A11	MVD Registers	0x10207000	MVD Services	New 3DS only?
Yes	A11	AXI	0x1020F000	TwlBg, GSP Services	CoreLink™ NIC-301 r1p0.
Yes	A11	DMA region	0x10300000-0x10400000		CDMA wants these addresses. Each page in this region corresponds to the same page in the 0x10100000-0x10200000 region. It is unknown if this is just a separate bus and/or if there are any differences in the registers.
Yes	A11	GPU Registers	0x10400000	Boot11, Kernel11, GSP Services

IO registers starting at physical address 0x10200000 are not accessible from the ARM9 (which includes all LCD/GPU registers). It seems IO registers below physical address 0x10100000 are not accessible from the ARM11 bus.

ARM11 kernel virtual address mappings for these registers varies for different builds. For ARM11 user mode applications you have:

physaddr = virtaddr - 0x1EC00000 + 0x10100000

IO Registers

Overview