[SC64][FW][SW] SD card byte swap on reads support (#39)

And other bug fixes related to DMA write mask

build.sh

@@ -8,6 +8,7 @@ PACKAGE_FILE_NAME="sc64-extra"
 
 TOP_FILES=(
     "./fw/ftdi/ft232h_config.xml"
+    "./fw/project/lcmxo2/impl1/fpga_max_frequency.txt"
     "./sw/tools/primer.py"
     "./sw/tools/requirements.txt"
     "./sc64-firmware-${SC64_VERSION}.bin"
@@ -90,6 +91,7 @@ build_update () {
         rm -f ../../sc64-firmware-*.bin
     fi
     GIT_INFO=""
+    GIT_INFO+=$'\n'"freq: $(cat ../../fw/project/lcmxo2/impl1/fpga_max_frequency.txt)"
     if [ ! -z "${SC64_VERSION}" ]; then GIT_INFO+=$'\n'"ver: $SC64_VERSION"; fi
     if [ ! -z "${GIT_BRANCH}" ]; then GIT_INFO+=$'\n'"branch: $GIT_BRANCH"; fi
     if [ ! -z "${GIT_TAG}" ]; then GIT_INFO+=$'\n'"tag: $GIT_TAG"; fi

docs/03_n64_commands.md

@@ -4,26 +4,27 @@
 
 ## N64 commands
 
-| id  | name                  | arg0       | arg1         | rsp0             | rsp1           | description                                        |
+| id  | name                  | arg0           | arg1         | rsp0             | rsp1           | description                                                |
-| --- | --------------------- | ---------- | ------------ | ---------------- | -------------- | -------------------------------------------------- |
+| --- | --------------------- | -------------- | ------------ | ---------------- | -------------- | ---------------------------------------------------------- |
-| `v` | **IDENTIFIER_GET**    | ---        | ---          | identifier       | ---            | Get flashcart identifier `SCv2`                    |
+| `v` | **IDENTIFIER_GET**    | ---            | ---          | identifier       | ---            | Get flashcart identifier `SCv2`                            |
-| `V` | **VERSION_GET**       | ---        | ---          | version          | ---            | Get flashcart firmware version                     |
+| `V` | **VERSION_GET**       | ---            | ---          | version          | ---            | Get flashcart firmware version                             |
-| `c` | **CONFIG_GET**        | config_id  | ---          | ---              | current_value  | Get config option                                  |
+| `c` | **CONFIG_GET**        | config_id      | ---          | ---              | current_value  | Get config option                                          |
-| `C` | **CONFIG_SET**        | config_id  | new_value    | ---              | previous_value | Set config option and get previous value           |
+| `C` | **CONFIG_SET**        | config_id      | new_value    | ---              | previous_value | Set config option and get previous value                   |
-| `c` | **SETTING_GET**       | setting_id | ---          | ---              | current_value  | Get persistent setting option                      |
+| `c` | **SETTING_GET**       | setting_id     | ---          | ---              | current_value  | Get persistent setting option                              |
-| `C` | **SETTING_SET**       | setting_id | new_value    | ---              | ---            | Set persistent setting option                      |
+| `C` | **SETTING_SET**       | setting_id     | new_value    | ---              | ---            | Set persistent setting option                              |
-| `t` | **TIME_GET**          | ---        | ---          | time_0           | time_1         | Get current RTC value                              |
+| `t` | **TIME_GET**          | ---            | ---          | time_0           | time_1         | Get current RTC value                                      |
-| `T` | **TIME_SET**          | time_0     | time_1       | ---              | ---            | Set new RTC value                                  |
+| `T` | **TIME_SET**          | time_0         | time_1       | ---              | ---            | Set new RTC value                                          |
-| `m` | **USB_READ**          | pi_address | length       | ---              | ---            | Receive data from USB to flashcart                 |
+| `m` | **USB_READ**          | pi_address     | length       | ---              | ---            | Receive data from USB to flashcart                         |
-| `M` | **USB_WRITE**         | pi_address | length/type  | ---              | ---            | Send data from from flashcart to USB               |
+| `M` | **USB_WRITE**         | pi_address     | length/type  | ---              | ---            | Send data from from flashcart to USB                       |
-| `u` | **USB_READ_STATUS**   | ---        | ---          | read_status/type | length         | Get USB read status and type/length                |
+| `u` | **USB_READ_STATUS**   | ---            | ---          | read_status/type | length         | Get USB read status and type/length                        |
-| `U` | **USB_WRITE_STATUS**  | ---        | ---          | write_status     | ---            | Get USB write status                               |
+| `U` | **USB_WRITE_STATUS**  | ---            | ---          | write_status     | ---            | Get USB write status                                       |
-| `i` | **SD_CARD_OP**        | pi_address | operation    | ---              | return_data    | Perform special operation on SD card               |
+| `i` | **SD_CARD_OP**        | pi_address     | operation    | ---              | return_data    | Perform special operation on SD card                       |
-| `I` | **SD_SECTOR_SET**     | sector     | ---          | ---              | ---            | Set starting sector for next SD card R/W operation |
+| `I` | **SD_SECTOR_SET**     | sector         | ---          | ---              | ---            | Set starting sector for next SD card R/W operation         |
-| `s` | **SD_READ**           | pi_address | sector_count | ---              | ---            | Read sectors from SD card to flashcart             |
+| `s` | **SD_READ**           | pi_address     | sector_count | ---              | ---            | Read sectors from SD card to flashcart                     |
-| `S` | **SD_WRITE**          | pi_address | sector_count | ---              | ---            | Write sectors from flashcart to SD card            |
+| `S` | **SD_WRITE**          | pi_address     | sector_count | ---              | ---            | Write sectors from flashcart to SD card                    |
-| `D` | **DD_SD_INFO**        | pi_address | table_size   | ---              | ---            | Set 64DD disk SD sector info                       |
+| `D` | **DD_SD_INFO**        | pi_address     | table_size   | ---              | ---            | Set 64DD disk SD sector info                               |
-| `W` | **WRITEBACK_SD_INFO** | pi_address | ---          | ---              | ---            | Load writeback SD sector table and enable it       |
+| `w` | **WRITEBACK_PENDING** | pending_status | ---          | ---              | ---            | Get save writeback status (is write queued to the SD card) |
-| `K` | **FLASH_PROGRAM**     | pi_address | length       | ---              | ---            | Program flash with bytes loaded into data buffer   |
+| `W` | **WRITEBACK_SD_INFO** | pi_address     | ---          | ---              | ---            | Load writeback SD sector table and enable it               |
-| `p` | **FLASH_WAIT_BUSY**   | wait       | ---          | erase_block_size | ---            | Wait until flash ready / get block erase size      |
+| `K` | **FLASH_PROGRAM**     | pi_address     | length       | ---              | ---            | Program flash with bytes loaded into data buffer           |
-| `P` | **FLASH_ERASE_BLOCK** | pi_address | ---          | ---              | ---            | Start flash block erase                            |
+| `p` | **FLASH_WAIT_BUSY**   | wait           | ---          | erase_block_size | ---            | Wait until flash ready / get block erase size              |
+| `P` | **FLASH_ERASE_BLOCK** | pi_address     | ---          | ---              | ---            | Start flash block erase                                    |

fw/project/lcmxo2/build.sh

@@ -1,5 +1,31 @@
 #!/bin/bash
 
+set -e
+
 source $bindir/diamond_env
 
 diamondc build.tcl
+
+MINIMUM_FREQ=$(cat impl1/sc64_impl1.twr \
+    | grep 'Preference: FREQUENCY NET "clk"' \
+    | head -1 \
+    | awk -F ' ' '{print $5}' \
+)
+
+DESIGN_FREQ=$(cat impl1/sc64_impl1.twr \
+    | sed -n '/Preference: FREQUENCY NET "clk"/,$p' \
+    | grep 'is the maximum frequency for this preference' \
+    | head -1 \
+    | awk -F ' ' '{print $2}' \
+    | sed 's/MHz//' \
+)
+
+echo "Minimum required frequency: $MINIMUM_FREQ MHz"
+echo "Maximum design frequency:   $DESIGN_FREQ MHz"
+
+if (( $(echo "$DESIGN_FREQ < $MINIMUM_FREQ" | bc -l) )); then
+    echo "Timing error detected, build failed"
+    exit 1
+fi
+
+echo -n "$DESIGN_FREQ MHz" > impl1/fpga_max_frequency.txt

fw/project/lcmxo2/sc64.lpf

@@ -21,8 +21,10 @@ IOBUF PORT "inclk" PULLMODE=NONE IO_TYPE=LVCMOS33 ;
 IOBUF PORT "mcu_clk" PULLMODE=NONE IO_TYPE=LVCMOS33 ;
 IOBUF PORT "mcu_cs" PULLMODE=UP IO_TYPE=LVCMOS33 ;
 IOBUF PORT "mcu_int" PULLMODE=UP IO_TYPE=LVCMOS33 ;
-IOBUF PORT "mcu_miso" IO_TYPE=LVCMOS33 PULLMODE=NONE ;
+IOBUF PORT "mcu_miso" PULLMODE=NONE IO_TYPE=LVCMOS33 ;
-IOBUF PORT "mcu_mosi" IO_TYPE=LVCMOS33 PULLMODE=NONE ;
+IOBUF PORT "mcu_mosi" PULLMODE=NONE IO_TYPE=LVCMOS33 ;
+IOBUF PORT "n64_cic_clk" PULLMODE=UP IO_TYPE=LVCMOS33 ;
+IOBUF PORT "n64_cic_dq" PULLMODE=UP IO_TYPE=LVCMOS33 ;
 IOBUF PORT "n64_irq" PULLMODE=UP IO_TYPE=LVCMOS33 ;
 IOBUF PORT "n64_nmi" PULLMODE=DOWN IO_TYPE=LVCMOS33 ;
 IOBUF PORT "n64_pi_ad[0]" PULLMODE=NONE IO_TYPE=LVCMOS33 ;
@@ -48,6 +50,7 @@ IOBUF PORT "n64_pi_write" PULLMODE=UP IO_TYPE=LVCMOS33 ;
 IOBUF PORT "n64_reset" PULLMODE=DOWN IO_TYPE=LVCMOS33 ;
 IOBUF PORT "n64_si_clk" PULLMODE=DOWN IO_TYPE=LVCMOS33 ;
 IOBUF PORT "n64_si_dq" PULLMODE=UP IO_TYPE=LVCMOS33 ;
+IOBUF PORT "n64_video_sync" PULLMODE=NONE IO_TYPE=LVCMOS33 ;
 IOBUF PORT "sd_clk" PULLMODE=UP IO_TYPE=LVCMOS33 ;
 IOBUF PORT "sd_cmd" PULLMODE=UP IO_TYPE=LVCMOS33 ;
 IOBUF PORT "sd_dat[0]" PULLMODE=UP IO_TYPE=LVCMOS33 ;
@@ -120,6 +123,8 @@ LOCATE COMP "mcu_miso" SITE "119" ;
 LOCATE COMP "mcu_mosi" SITE "120" ;
 LOCATE COMP "n64_irq" SITE "32" ;
 LOCATE COMP "n64_nmi" SITE "28" ;
+LOCATE COMP "n64_cic_clk" SITE "34" ;
+LOCATE COMP "n64_cic_dq" SITE "35" ;
 LOCATE COMP "n64_pi_ad[0]" SITE "60" ;
 LOCATE COMP "n64_pi_ad[1]" SITE "58" ;
 LOCATE COMP "n64_pi_ad[10]" SITE "42" ;
@@ -143,6 +148,7 @@ LOCATE COMP "n64_pi_write" SITE "49" ;
 LOCATE COMP "n64_reset" SITE "31" ;
 LOCATE COMP "n64_si_clk" SITE "33" ;
 LOCATE COMP "n64_si_dq" SITE "27" ;
+LOCATE COMP "n64_video_sync" SITE "26" ;
 LOCATE COMP "sd_clk" SITE "111" ;
 LOCATE COMP "sd_cmd" SITE "112" ;
 LOCATE COMP "sd_dat[0]" SITE "110" ;

fw/rtl/mcu/mcu_top.sv

@@ -364,6 +364,7 @@ module mcu_top (
     logic bootloader_skip;
 
     assign n64_scb.cfg_identifier = 32'h53437632;
+    assign usb_dma_scb.byte_swap = 1'b0;
 
     logic dd_bm_ack;
 
@@ -577,7 +578,8 @@ module mcu_top (
 
                 REG_SD_DMA_SCR: begin
                     reg_rdata <= {
-                        28'd0,
+                        27'd0,
+                        sd_dma_scb.byte_swap,
                         sd_dma_scb.busy,
                         sd_dma_scb.direction,
                         2'b00
@@ -855,11 +857,10 @@ module mcu_top (
                 end
 
                 REG_SD_DMA_SCR: begin
-                    {
+                    sd_dma_scb.byte_swap <= reg_wdata[4];
-                        sd_dma_scb.direction,
+                    sd_dma_scb.direction <= reg_wdata[2];
-                        sd_dma_scb.stop,
+                    sd_dma_scb.stop <= reg_wdata[1];
-                        sd_dma_scb.start
+                    sd_dma_scb.start <= reg_wdata[0];
-                    } <= reg_wdata[2:0];
                 end
 
                 REG_DD_SCR: begin

fw/rtl/memory/memory_dma.sv

@@ -4,6 +4,7 @@ interface dma_scb ();
     logic stop;
     logic busy;
     logic direction;
+    logic byte_swap;
     logic [26:0] starting_address;
     logic [26:0] transfer_length;
 
@@ -12,6 +13,7 @@ interface dma_scb ();
         output stop,
         input busy,
         output direction,
+        output byte_swap,
         output starting_address,
         output transfer_length
     );
@@ -21,6 +23,7 @@ interface dma_scb ();
         input stop,
         output busy,
         input direction,
+        input byte_swap,
         input starting_address,
         input transfer_length
     );
@@ -61,6 +64,7 @@ module memory_dma (
 
     // RX FIFO controller
 
+    logic [1:0] rx_wmask;
     logic rx_rdata_pop;
     logic rx_rdata_shift;
     logic rx_rdata_valid;
@@ -88,11 +92,11 @@ module memory_dma (
 
         if (dma_start) begin
             if (dma_scb.starting_address[0]) begin
-                mem_bus.wmask <= 2'b01;
+                rx_wmask <= 2'b01;
                 rx_buffer_counter <= 2'd1;
                 rx_buffer_valid_counter <= 2'd1;
             end else begin
-                mem_bus.wmask <= 2'b11;
+                rx_wmask <= 2'b11;
                 rx_buffer_counter <= 2'd0;
                 rx_buffer_valid_counter <= 2'd0;
             end
@@ -103,16 +107,21 @@ module memory_dma (
         end
 
         if (rx_rdata_shift || rx_rdata_valid) begin
-            rx_buffer <= {rx_buffer[7:0], fifo_bus.rx_rdata};
+            if (dma_scb.byte_swap) begin
+                rx_buffer <= {fifo_bus.rx_rdata, rx_buffer[15:8]};
+            end else begin
+                rx_buffer <= {rx_buffer[7:0], fifo_bus.rx_rdata};
+            end
             rx_buffer_valid_counter <= rx_buffer_valid_counter + 1'd1;
             if (remaining == 27'd0 && rx_buffer_counter == 2'd1) begin
-                mem_bus.wmask <= 2'b10;
+                rx_wmask <= 2'b10;
                 rx_rdata_shift <= 1'b1;
                 rx_buffer_counter <= rx_buffer_counter + 1'd1;
             end
         end
 
         if (rx_buffer_valid && !mem_bus.request) begin
+            rx_wmask <= 2'b11;
             rx_buffer_counter <= 2'd0;
             rx_buffer_valid_counter <= 2'd0;
         end
@@ -209,6 +218,7 @@ module memory_dma (
                 if (mem_bus.write) begin
                     if (rx_buffer_valid) begin
                         mem_bus.request <= 1'b1;
+                        mem_bus.wmask <= rx_wmask;
                         mem_bus.wdata <= rx_buffer;
                     end
                 end else begin

fw/rtl/top.sv

@@ -45,7 +45,12 @@ module top (
     input mcu_clk,
     input mcu_cs,
     input mcu_mosi,
-    output mcu_miso
+    output mcu_miso,
+
+    // Unused I/O
+    output n64_cic_clk,
+    output n64_cic_dq,
+    output n64_video_sync
 );
 
     logic clk;
@@ -264,4 +269,11 @@ module top (
         .vendor_scb(vendor_scb)
     );
 
+
+    // Unused I/O
+
+    assign n64_cic_clk = 1'bZ;
+    assign n64_cic_dq = 1'bZ;
+    assign n64_video_sync = 1'bZ;
+
 endmodule

sw/bootloader/src/sc64.c

@@ -52,6 +52,8 @@ typedef enum {
     SD_CARD_OP_INIT = 1,
     SD_CARD_OP_GET_STATUS = 2,
     SD_CARD_OP_GET_INFO = 3,
+    SD_CARD_OP_BYTE_SWAP_ON = 4,
+    SD_CARD_OP_BYTE_SWAP_OFF = 5,
 } sd_card_op_t;
 
 
@@ -235,6 +237,14 @@ bool sc64_sd_card_get_info (void *address) {
     return false;
 }
 
+bool sc64_sd_set_byte_swap (bool enabled) {
+    uint32_t args[2] = { (uint32_t) (NULL), enabled ? SD_CARD_OP_BYTE_SWAP_ON : SD_CARD_OP_BYTE_SWAP_OFF };
+    if (sc64_execute_cmd(SC64_CMD_SD_CARD_OP, args, NULL)) {
+        return true;
+    }
+    return false;
+}
+
 bool sc64_sd_read_sectors (void *address, uint32_t sector, uint32_t count) {
     uint32_t sector_set_args[2] = { sector, 0 };
     uint32_t read_args[2] = { (uint32_t) (address), count };

sw/bootloader/src/sc64.h

@@ -86,6 +86,7 @@ typedef enum {
     SD_CARD_STATUS_INITIALIZED = (1 << 1),
     SD_CARD_STATUS_TYPE_BLOCK = (1 << 2),
     SD_CARD_STATUS_50MHZ_MODE = (1 << 3),
+    SD_CARD_STATUS_BYTE_SWAP = (1 << 4),
 } sc64_sd_card_status_t;
 
 typedef struct {
@@ -143,6 +144,7 @@ bool sc64_sd_card_init (void);
 bool sc64_sd_card_deinit (void);
 sc64_sd_card_status_t sc64_sd_card_get_status (void);
 bool sc64_sd_card_get_info (void *address);
+bool sc64_sd_set_byte_swap (bool enabled);
 bool sc64_sd_write_sectors (void *address, uint32_t sector, uint32_t count);
 bool sc64_sd_read_sectors (void *address, uint32_t sector, uint32_t count);
 bool sc64_dd_set_sd_disk_info (void *address, uint32_t length);

sw/bootloader/src/test.c

@@ -57,6 +57,9 @@ static void test_sd_card (void) {
     if (card_status & SD_CARD_STATUS_50MHZ_MODE) {
         display_printf("SD card runs at 50 MHz clock speed\n");
     }
+    if (card_status & SD_CARD_STATUS_BYTE_SWAP) {
+        display_printf("SD card read byte swap is enabled\n");
+    }
 
     if (sc64_sd_card_get_info((uint32_t *) (SC64_BUFFERS->BUFFER))) {
         display_printf("SD card get info error!\n");

sw/controller/src/cfg.c

@@ -79,6 +79,8 @@ typedef enum {
     SD_CARD_OP_INIT = 1,
     SD_CARD_OP_GET_STATUS = 2,
     SD_CARD_OP_GET_INFO = 3,
+    SD_CARD_OP_BYTE_SWAP_ON = 4,
+    SD_CARD_OP_BYTE_SWAP_OFF = 5,
 } sd_card_op_t;
 
 typedef enum {
@@ -176,7 +178,7 @@ static void cfg_change_scr_bits (uint32_t mask, bool value) {
 }
 
 static bool cfg_set_save_type (save_type_t save_type) {
-    if (save_type > SAVE_TYPE_SRAM_BANKED) {
+    if (save_type > SAVE_TYPE_SRAM_1M) {
         return true;
     }
 
@@ -575,6 +577,18 @@ void cfg_process (void) {
                             return;
                         }
                         break;
+                    case SD_CARD_OP_BYTE_SWAP_ON:
+                        if (sd_set_byte_swap(true)) {
+                            cfg_set_error(CFG_ERROR_SD_CARD);
+                            return;
+                        }
+                        break;
+                    case SD_CARD_OP_BYTE_SWAP_OFF:
+                        if (sd_set_byte_swap(false)) {
+                            cfg_set_error(CFG_ERROR_SD_CARD);
+                            return;
+                        }
+                        break;
                     default:
                         cfg_set_error(CFG_ERROR_BAD_ARGUMENT);
                         return;
@@ -625,6 +639,10 @@ void cfg_process (void) {
                 dd_set_sd_info(args[0], args[1]);
                 break;
 
+            case 'w':
+                args[0] = writeback_pending();
+                break;
+
             case 'W':
                 if (cfg_translate_address(&args[0], WRITEBACK_SECTOR_TABLE_SIZE, (SDRAM | BRAM))) {
                     cfg_set_error(CFG_ERROR_BAD_ADDRESS);

sw/controller/src/fpga.h

@@ -92,6 +92,7 @@ typedef enum {
 #define DMA_SCR_STOP                    (1 << 1)
 #define DMA_SCR_DIRECTION               (1 << 2)
 #define DMA_SCR_BUSY                    (1 << 3)
+#define DMA_SCR_BYTE_SWAP               (1 << 4)
 
 #define CFG_SCR_BOOTLOADER_ENABLED      (1 << 0)
 #define CFG_SCR_BOOTLOADER_SKIP         (1 << 1)

sw/controller/src/hw.c

@@ -508,7 +508,7 @@ static void hw_init_crc (void) {
 
 static void hw_init_misc (void) {
     hw_gpio_init(GPIO_ID_N64_RESET, GPIO_INPUT, GPIO_PP, GPIO_SPEED_VLOW, GPIO_PULL_DOWN, GPIO_AF_0, 0);
-    hw_gpio_init(GPIO_ID_N64_CIC_CLK, GPIO_INPUT, GPIO_PP, GPIO_SPEED_VLOW, GPIO_PULL_DOWN, GPIO_AF_0, 0);
+    hw_gpio_init(GPIO_ID_N64_CIC_CLK, GPIO_INPUT, GPIO_PP, GPIO_SPEED_VLOW, GPIO_PULL_UP, GPIO_AF_0, 0);
     hw_gpio_init(GPIO_ID_N64_CIC_DQ, GPIO_OUTPUT, GPIO_OD, GPIO_SPEED_VLOW, GPIO_PULL_UP, GPIO_AF_0, 1);
     hw_gpio_init(GPIO_ID_FPGA_INT, GPIO_INPUT, GPIO_PP, GPIO_SPEED_VLOW, GPIO_PULL_UP, GPIO_AF_0, 0);
     hw_gpio_init(GPIO_ID_RTC_MFP, GPIO_INPUT, GPIO_PP, GPIO_SPEED_VLOW, GPIO_PULL_UP, GPIO_AF_0, 0);

sw/controller/src/sd.c

@@ -7,6 +7,7 @@
 
 
 #define SD_INIT_BUFFER_ADDRESS          (0x05002800UL)
+#define BYTE_SWAP_ADDRESS_END           (0x05000000UL)
 
 #define CMD6_ARG_CHECK_HS               (0x00FFFFF1UL)
 #define CMD6_ARG_SWITCH_HS              (0x80FFFFF1UL)
@@ -67,6 +68,7 @@ struct process {
     uint8_t csd[16];
     uint8_t cid[16];
     volatile bool timeout;
+    bool byte_swap;
 };
 
 
@@ -178,6 +180,9 @@ static void sd_dat_prepare (uint32_t address, uint32_t count, dat_mode_t mode) {
     if (mode == DAT_READ) {
         sd_dat |= SD_DAT_START_READ;
         sd_dma_scr |= DMA_SCR_DIRECTION;
+        if (p.byte_swap && (address < BYTE_SWAP_ADDRESS_END)) {
+            sd_dma_scr |= DMA_SCR_BYTE_SWAP;
+        }
     } else {
         sd_dat |= SD_DAT_START_WRITE;
     }
@@ -217,6 +222,8 @@ bool sd_card_init (void) {
     uint32_t rsp;
     uint16_t tmp;
 
+    p.byte_swap = false;
+
     if (p.card_initialized) {
         return false;
     }
@@ -336,6 +343,7 @@ bool sd_card_init (void) {
 void sd_card_deinit (void) {
     if (p.card_initialized) {
         p.card_initialized = false;
+        p.byte_swap = false;
         sd_set_clock(CLOCK_400KHZ);
         sd_cmd(0, 0, RSP_NONE, NULL);
         sd_set_clock(CLOCK_STOP);
@@ -348,11 +356,13 @@ bool sd_card_is_inserted (void) {
 
 uint32_t sd_card_get_status (void) {
     uint32_t scr = fpga_reg_get(REG_SD_SCR);
+    uint32_t byte_swap = p.byte_swap ? 1 : 0;
     uint32_t clock_mode_50mhz = ((scr & SD_SCR_CLOCK_MODE_MASK) == SD_SCR_CLOCK_MODE_50MHZ) ? 1 : 0;
     uint32_t card_type_block = p.card_type_block ? 1 : 0;
     uint32_t card_initialized = p.card_initialized ? 1 : 0;
     uint32_t card_inserted = (scr & SD_SCR_CARD_INSERTED) ? 1 : 0;
     return (
+        (byte_swap << 4) |
         (clock_mode_50mhz << 3) |
         (card_type_block << 2) |
         (card_initialized << 1) |
@@ -371,6 +381,14 @@ bool sd_card_get_info (uint32_t address) {
     return false;
 }
 
+bool sd_set_byte_swap (bool enabled) {
+    if (!p.card_initialized) {
+        return true;
+    }
+    p.byte_swap = enabled;
+    return false;
+}
+
 bool sd_write_sectors (uint32_t address, uint32_t sector, uint32_t count) {
     if (!p.card_initialized || (count == 0)) {
         return true;
@@ -406,6 +424,10 @@ bool sd_read_sectors (uint32_t address, uint32_t sector, uint32_t count) {
         return true;
     }
 
+    if (p.byte_swap && ((address % 2) != 0)) {
+        return true;
+    }
+
     if (!p.card_type_block) {
         sector *= SD_SECTOR_SIZE;
     }
@@ -463,11 +485,12 @@ bool sd_optimize_sectors (uint32_t address, uint32_t *sector_table, uint32_t cou
 
 void sd_init (void) {
     p.card_initialized = false;
+    p.byte_swap = false;
     sd_set_clock(CLOCK_STOP);
 }
 
 void sd_process (void) {
-    if (!sd_card_is_inserted()) {
+    if (p.card_initialized && !sd_card_is_inserted()) {
         sd_card_deinit();
     }
 }

sw/controller/src/sd.h

@@ -17,6 +17,7 @@ void sd_card_deinit (void);
 bool sd_card_is_inserted (void);
 uint32_t sd_card_get_status (void);
 bool sd_card_get_info (uint32_t address);
+bool sd_set_byte_swap (bool enabled);
 bool sd_write_sectors (uint32_t address, uint32_t sector, uint32_t count);
 bool sd_read_sectors (uint32_t address, uint32_t sector, uint32_t count);
 bool sd_optimize_sectors (uint32_t address, uint32_t *sector_table, uint32_t count, sd_process_sectors_t sd_process_sectors);

sw/controller/src/writeback.c

@@ -124,6 +124,10 @@ void writeback_disable (void) {
     timer_set(TIMER_ID_WRITEBACK, 0);
 }
 
+bool writeback_pending (void) {
+    return p.enabled && p.pending;
+}
+
 void writeback_init (void) {
     p.enabled = false;
     p.pending = false;

sw/controller/src/writeback.h

@@ -18,6 +18,7 @@ typedef enum {
 void writeback_load_sector_table (uint32_t address);
 void writeback_enable (writeback_mode_t mode);
 void writeback_disable (void);
+bool writeback_pending (void);
 void writeback_init (void);
 void writeback_process (void);
 

sw/deployer/src/main.rs

@@ -157,6 +157,10 @@ struct DebugArgs {
     /// Use EUC-JP encoding for text printing
     #[arg(long)]
     euc_jp: bool,
+
+    /// Do not enable save writeback via USB
+    #[arg(long)]
+    no_writeback: bool
 }
 
 #[derive(Args)]
@@ -612,7 +616,9 @@ fn handle_debug_command(connection: Connection, args: &DebugArgs) -> Result<(),
                 .bright_blue()
         );
     }
-    sc64.set_save_writeback(true)?;
+    if !args.no_writeback {
+        sc64.set_save_writeback(true)?;
+    }
 
     println!("{}: Started", "[Debug]".bold());
 
@@ -639,7 +645,9 @@ fn handle_debug_command(connection: Connection, args: &DebugArgs) -> Result<(),
         }
     }
 
-    sc64.set_save_writeback(false)?;
+    if !args.no_writeback {
+        sc64.set_save_writeback(false)?;
+    }
     if args.isv.is_some() {
         sc64.configure_is_viewer_64(None)?;
         println!("{}: Stopped listening", "[IS-Viewer 64]".bold());