platform: add DMA support for M3DS (#167)

README.md

@@ -34,7 +34,7 @@ Note that there can be some game compatibility differences between different pla
 | EZP           | EZ-Flash Parallel                                                                              | ❌ |
 | G003          | M3i Zero (GMP-Z003)                                                                            | ✅ |
 | ISNITRO       | Supports the IS-NITRO-EMULATOR through agb semihosting.                                        | ❌ |
-| M3DS          | M3 DS Real, M3i Zero, iTouchDS, r4rts.com, r4isdhc.com RTS (black)                             | ❌ |
+| M3DS          | M3 DS Real, M3i Zero, iTouchDS, r4rts.com, r4isdhc.com RTS (black)                             | ✅ |
 | M3CF          | M3 Compact Flash (Slot-2 flashcart)                                                            | ❌ |
 | MELONDS       | Melon DS support for testing purposes only.                                                    | ❌ |
 | MMCF          | DATEL Max Media Dock Compact Flash (Slot-2 flashcart)                                          | ❌ |

arm9/source/patches/platform/m3ds/M3DSLoaderPlatform.h

@@ -1,5 +1,6 @@
 #pragma once
 #include "../LoaderPlatform.h"
+#include "M3DSReadSdSectorsDmaPatchCode.h"
 #include "M3DSReadSdSectorsPatchCode.h"
 #include "M3DSWriteSdSectorsPatchCode.h"
 
@@ -20,6 +21,15 @@ public:
         });
     }
 
+    const IReadSectorsDmaPatchCode* CreateSdReadDmaPatchCode(PatchCodeCollection& patchCodeCollection,
+        PatchHeap& patchHeap, const void* miiCardDmaCopy32Ptr) const override
+    {
+        return patchCodeCollection.AddUniquePatchCode<M3DSReadSdSectorsDmaPatchCode>(
+            patchHeap, miiCardDmaCopy32Ptr,
+            patchCodeCollection.AddUniquePatchCode<M3DSReadSdSectorsDmaHelperPatchCode>(patchHeap)
+        );
+    }
+
     const IWriteSectorsPatchCode* CreateSdWritePatchCode(
         PatchCodeCollection& patchCodeCollection, PatchHeap& patchHeap) const override
     {
@@ -34,4 +44,6 @@ public:
     }
 
     LoaderPlatformType GetPlatformType() const override { return LoaderPlatformType::Slot1; }
+
+    bool HasDmaSdReads() const override { return true; }
 };

arm9/source/patches/platform/m3ds/M3DSReadSdSectorsDmaPatchCode.h

@@ -0,0 +1,63 @@
+#pragma once
+#include "sections.h"
+#include "patches/PatchCode.h"
+#include "../IReadSectorsDmaPatchCode.h"
+
+DEFINE_SECTION_SYMBOLS(m3ds_readsdsectorsdma);
+DEFINE_SECTION_SYMBOLS(m3ds_readsdsectorsdma_helper);
+
+extern "C" void m3ds_readSdSectorsDma(u32 srcSector, u32 previousSrcSector, u32 dmaChannel, void* dst);
+extern "C" void m3ds_finishReadSdSectorsDma(void);
+extern "C" void m3ds_readSdSectorsDma_applyCommand(void);
+extern "C" void m3ds_sdStopTransmission(void);
+
+extern u32 m3ds_readSdSectorsDma_miiCardDmaCopy32Ptr;
+extern u32 m3ds_readSdSectorsDma_applyCommand_address;
+extern u32 m3ds_readSdSectorsDma_sdStopTransmission_address;
+
+class M3DSReadSdSectorsDmaHelperPatchCode : public PatchCode
+{
+public:
+    explicit M3DSReadSdSectorsDmaHelperPatchCode(PatchHeap& patchHeap)
+        : PatchCode(SECTION_START(m3ds_readsdsectorsdma_helper),
+            SECTION_SIZE(m3ds_readsdsectorsdma_helper), patchHeap) { }
+
+    const void* GetReadSdSectorsDmaApplyCommandFunction() const
+    {
+        return (const void*)GetAddressAtTarget((void*)m3ds_readSdSectorsDma_applyCommand);
+    }
+
+    const void* GetSdStopTransmissionFunction() const
+    {
+        return (const void*)GetAddressAtTarget((void*)m3ds_sdStopTransmission);
+    }
+};
+
+class M3DSReadSdSectorsDmaPatchCode : public PatchCode, public IReadSectorsDmaPatchCode
+{
+public:
+    M3DSReadSdSectorsDmaPatchCode(PatchHeap& patchHeap, const void* miiCardDmaCopy32Ptr,
+        const M3DSReadSdSectorsDmaHelperPatchCode* m3dsReadSdSectorsDmaHelperPatchCode)
+        : PatchCode(SECTION_START(m3ds_readsdsectorsdma), SECTION_SIZE(m3ds_readsdsectorsdma), patchHeap)
+    {
+        m3ds_readSdSectorsDma_miiCardDmaCopy32Ptr = (u32)miiCardDmaCopy32Ptr;
+        m3ds_readSdSectorsDma_applyCommand_address
+            = (u32)m3dsReadSdSectorsDmaHelperPatchCode->GetReadSdSectorsDmaApplyCommandFunction();
+        m3ds_readSdSectorsDma_sdStopTransmission_address
+            = (u32)m3dsReadSdSectorsDmaHelperPatchCode->GetSdStopTransmissionFunction();
+        _sdReadDmaFinishFunc = (ReadSectorsDmaFinishFunc)m3dsReadSdSectorsDmaHelperPatchCode->GetSdStopTransmissionFunction();
+    }
+
+    const ReadSectorsDmaFunc GetReadSectorsDmaFunction() const override
+    {
+        return (const ReadSectorsDmaFunc)GetAddressAtTarget((void*)m3ds_readSdSectorsDma);
+    }
+
+    const ReadSectorsDmaFinishFunc GetReadSectorsDmaFinishFunction() const override
+    {
+        return _sdReadDmaFinishFunc;
+    }
+
+private:
+    ReadSectorsDmaFinishFunc _sdReadDmaFinishFunc = 0;
+};

arm9/source/patches/platform/m3ds/M3DSReadSdSectorsDmaPatchCode.s

@@ -0,0 +1,148 @@
+.cpu arm946e-s
+.section "m3ds_readsdsectorsdma", "ax"
+.syntax unified
+.thumb
+
+// r0 = src sector
+// r1 = previous src sector
+// r2 = dma channel
+// r3 = dst
+.global m3ds_readSdSectorsDma
+.type m3ds_readSdSectorsDma, %function
+m3ds_readSdSectorsDma:
+    push {r4-r7,lr}
+
+    ldr r4, =0x040001A0
+    movs r7, #0x80
+    strb r7, [r4,#0x1]
+
+    cmp r1, #0 // if first sector
+    beq sector_loop // first sector, skip poll
+
+    subs r1, r0, r1
+    cmp r1, #1 // if sequential
+    beq sector_loop_next_sequential
+
+    ldr r7, m3ds_readSdSectorsDma_sdStopTransmission_address
+    blx r7
+
+sector_loop:
+    // request sd read for sector 0xaabbccdd
+    // B1 aa bb cc dd 00 00 00
+    movs r7, #0xB1
+    strb r7, [r4,#0x8]
+    lsrs r7, r0, #24
+    strb r7, [r4,#0x9]
+    lsrs r7, r0, #16
+    strb r7, [r4,#0xA]
+    lsrs r7, r0, #8
+    strb r7, [r4,#0xB]
+    lsls r7, r0, #24
+    lsrs r7, r7, #24 // r7 = dd
+    str r7, [r4,#0xC] // storing as little-endian puts the bottom 8 bits as first byte
+
+    b cmd_poll_loop
+
+sector_loop_next_sequential:
+    // request sd read for next contiguous sector
+    // starting from sector 0xaabbccdd
+    // B2 aa bb cc dd 00 00 00
+    movs r7, #0xB2
+    strb r7, [r4,#0x8]
+
+cmd_poll_loop:
+    ldr r1, =0x04100010
+    ldr r7, m3ds_readSdSectorsDma_applyCommand_address
+    blx r7
+
+    // Setup data read card command
+    movs r7, #0xBA
+    strb r7, [r4,#0x8]
+
+readDataWithDma:
+    movs r0, r2 // DMA channel
+    movs r2, r3 // Destination
+    movs r3, #1
+    lsls r3, r3, #9 // (1 << 9) = 512 = count
+
+    ldr r6, m3ds_readSdSectorsDma_miiCardDmaCopy32Ptr
+    blx r6
+
+BA_data_dma:
+    movs r7, #0xC0 // select rom mode, with irq
+    strb r7, [r4,#0x1]
+    movs r7, #0xA1
+    strb r7, [r4,#0x7]
+
+    pop {r4-r7,pc}
+
+.balign 4
+
+.global m3ds_readSdSectorsDma_miiCardDmaCopy32Ptr
+m3ds_readSdSectorsDma_miiCardDmaCopy32Ptr:
+    .word 0
+
+.global m3ds_readSdSectorsDma_applyCommand_address
+m3ds_readSdSectorsDma_applyCommand_address:
+    .word 0
+
+.global m3ds_readSdSectorsDma_sdStopTransmission_address
+m3ds_readSdSectorsDma_sdStopTransmission_address:
+    .word 0
+
+.pool
+
+
+.section "m3ds_readsdsectorsdma_helper", "ax"
+
+.global m3ds_readSdSectorsDma_applyCommand
+.type m3ds_readSdSectorsDma_applyCommand, %function
+m3ds_readSdSectorsDma_applyCommand:
+    ldr r7, =0xA7586000
+    str r7, [r4,#0x4]
+
+cmd_poll_transfer_loop:
+    ldrb r7, [r4,#0x6]
+    lsrs r7, r7, #8
+    bcc cmd_poll_check_transfer_end
+
+    ldr r5, [r1]
+
+cmd_poll_check_transfer_end:
+    ldrb r7, [r4,#0x7]
+    lsrs r7, r7, #8
+    bcs cmd_poll_transfer_loop
+
+    cmp r5, #0
+    bne m3ds_readSdSectorsDma_applyCommand
+    bx lr
+
+.balign 4
+
+.pool
+
+.global m3ds_sdStopTransmission
+.type m3ds_sdStopTransmission, %function
+m3ds_sdStopTransmission:
+    push {r4-r5,lr}
+    ldr r4, =0x040001A0
+    movs r5, #0xB3
+    str r5, [r4, #0x8]
+    movs r5, #0
+    str r5, [r4, #0xC]
+    ldr r5, =0xA0486100
+    str r5, [r4, #0x4]
+
+// loop until card is ready
+stopSdTransmission_read_loop:
+    // Check MCCNT1_ENABLE
+    ldrb r5, [r4,#7]
+    lsrs r5, r5, #8
+    bcs stopSdTransmission_read_loop
+    pop {r4-r5,pc}
+
+.balign 4
+
+.pool
+
+.end