reboot into ram wip

bootloader.c

@@ -380,20 +380,16 @@ __attribute__((naked)) int main(void) {
     ACTIVE_CONFIG = 0;
     const uint8_t *outputting_desc = 0;
     CTRL_XFER_DESC_SZ = 0;
+    ADDRESS_HI = 0;
 
     // bits [31:24] = additional sense code
     // bits [23:20] = sense key
     // bits [7:0] = state
     uint32_t msc_state = STATE_WANT_CBW;
-    // when reading:
-    // [31:16] = current lba
-    // [15:0] = blocks left
-    // when writing:
-    // [31:16] = ignored
-    // [15:0] = blocks left
 
     UF2_GOT_BLOCKS[35] = 0;
 
+
     while (1) {
         uint32_t usb_int_status = R16_USBD_ISTR;
         if (usb_int_status & (1 << 10)) {
@@ -849,7 +845,6 @@ __attribute__((naked)) int main(void) {
                         msc_state = (msc_state & 0xffffff00) | STATE_WANT_CBW;
                         break;
                     case STATE_SENT_CSW_REBOOT:
-                        // todo reboot into ram
                         STK_CMPLR = (50 /* ms */ * 12000 /* assume 96 MHz system clock, div8 */);
                         STK_CTLR = 0b111000;
                         STK_CTLR = 0b111001;
@@ -858,10 +853,15 @@ __attribute__((naked)) int main(void) {
                         STK_SR = 0;
                         R16_USBD_CNTR = 0b11;
                         R32_EXTEN_CTR &= ~(1 << 1);
-                        // wtf why does this work and the other stuff doesn't?
+                        if (ADDRESS_HI >> 8 == 0x20) {
-                        R16_BKP_DATAR10 = 0x4170;
+                            // ram boot
-                        PFIC_CFGR = 0xbeef0080;
+                            ((void (*)())0x20000000)();
-                        while (1) { asm volatile(""); }
+                        } else {
+                            // wtf why does this work and the other stuff doesn't?
+                            R16_BKP_DATAR10 = 0x4170;
+                            PFIC_CFGR = 0xbeef0080;
+                            while (1) { asm volatile(""); }
+                        }
                         break;
                     case STATE_SENT_DATA_IN:
                         make_msc_csw(dCSWTag, 0);

minimal-payload-ram/.gdbinit

@@ -0,0 +1,2 @@
+tar ext localhost:3333
+load

minimal-payload-ram/Makefile

@@ -0,0 +1,33 @@
+.PHONY: all clean
+
+RV_ARCH = rv32imacxw
+
+CC = riscv-none-elf-gcc
+OBJDUMP = riscv-none-elf-objdump
+OBJCOPY = riscv-none-elf-objcopy
+CFLAGS = -ggdb3 -Os -march=$(RV_ARCH) -ffunction-sections -fdata-sections
+LDFLAGS = -ggdb3 -march=$(RV_ARCH) -Wl,--gc-sections --specs=nosys.specs
+
+all: main.uf2
+
+main.elf: startup.o main.o
+
+%.uf2: %.bin
+	~/code/uf2/utils/uf2conv.py -c -f 0xdeadbeef -b 0x20000000 -o $@.temp $<
+	xxd $@.temp | sed 's/5546 320a 5751 5d9e 0020 0000/5546 320a 5751 5d9e 0120 0000/g' | xxd -r >$@
+
+%.bin: %.elf
+	$(OBJCOPY) -O binary $< $@
+
+%.elf: linker.lds
+	$(CC) -Xlinker -Map=$(@:.elf=.map) -Wl,--script=linker.lds -nostartfiles -o $@ $(filter-out linker.lds,$+)
+	$(OBJDUMP) -xdsS $@ >$(@:.elf=.dump)
+
+%.o: %.S
+	$(CC) $(CFLAGS) -c -o $@ $<
+
+%.o: %.c
+	$(CC) $(CFLAGS) -c -o $@ $<
+
+clean:
+	rm -f *.o *.elf *.map *.dump

minimal-payload-ram/linker.lds

@@ -0,0 +1,97 @@
+ENTRY( _start )
+
+__stack_size = 512;
+PROVIDE( _stack_size = __stack_size );
+
+MEMORY
+{
+    /* CH32V20x_D6 -> 10 KB SRAM */
+    RAM (xrw) : ORIGIN = 0x20000000, LENGTH = 10K
+}
+
+SECTIONS
+{
+    .vector :
+    {
+        *(.vector);
+        . = ALIGN(4);
+    } >RAM
+    
+    .text :
+    {
+        *(.text)
+        *(.text.*)
+        *(.rodata)
+        *(.rodata*)
+        *(.gnu.linkonce.t.*)
+        . = ALIGN(4);
+    } >RAM
+
+    .preinit_array :
+    {
+        PROVIDE_HIDDEN (__preinit_array_start = .);
+        KEEP (*(.preinit_array))
+        PROVIDE_HIDDEN (__preinit_array_end = .);
+    } >RAM
+
+    .init_array :
+    {
+        PROVIDE_HIDDEN (__init_array_start = .);
+        KEEP (*(SORT_BY_INIT_PRIORITY(.init_array.*) SORT_BY_INIT_PRIORITY(.ctors.*)))
+        KEEP (*(.init_array EXCLUDE_FILE (*crtbegin.o *crtbegin?.o *crtend.o *crtend?.o ) .ctors))
+        PROVIDE_HIDDEN (__init_array_end = .);
+    } >RAM
+
+    .fini_array :
+    {
+        PROVIDE_HIDDEN (__fini_array_start = .);
+        KEEP (*(SORT_BY_INIT_PRIORITY(.fini_array.*) SORT_BY_INIT_PRIORITY(.dtors.*)))
+        KEEP (*(.fini_array EXCLUDE_FILE (*crtbegin.o *crtbegin?.o *crtend.o *crtend?.o ) .dtors))
+        PROVIDE_HIDDEN (__fini_array_end = .);
+    } >RAM
+
+    PROVIDE(_data_lma = .);
+
+    .data :
+    {
+        PROVIDE(_data_vma = .);
+        *(.gnu.linkonce.r.*)
+        *(.data .data.*)
+        *(.gnu.linkonce.d.*)
+        . = ALIGN(4);
+        PROVIDE( __global_pointer$ = . + 0x800 );
+        *(.sdata .sdata.*)
+        *(.sdata2.*)
+        *(.gnu.linkonce.s.*)
+        . = ALIGN(4);
+        *(.srodata.cst16)
+        *(.srodata.cst8)
+        *(.srodata.cst4)
+        *(.srodata.cst2)
+        *(.srodata .srodata.*)
+        . = ALIGN(4);
+        PROVIDE( _edata = .);
+    } >RAM
+
+    .bss :
+    {
+        PROVIDE( _sbss = .);
+        *(.sbss*)
+        *(.gnu.linkonce.sb.*)
+        *(.bss*)
+        *(.gnu.linkonce.b.*)
+        *(COMMON*)
+        . = ALIGN(4);
+        PROVIDE( _ebss = .);
+    } >RAM
+
+    PROVIDE( _end = _ebss);
+
+    .stack ORIGIN(RAM) + LENGTH(RAM) - __stack_size :
+    {
+        PROVIDE( _heap_end = . );
+        PROVIDE( _susrstack = . );
+        . = . + __stack_size;
+        PROVIDE( _eusrstack = .);
+    } >RAM 
+}

minimal-payload-ram/main.c

@@ -0,0 +1,27 @@
+#include <stdint.h>
+
+#pragma GCC diagnostic ignored "-Wprio-ctor-dtor"
+__attribute__((constructor(0))) static void setup_qingke() {
+    asm volatile(
+        // Undocumented "Configure pipelining and instruction prediction"
+        "li t0, 0x1f\n"
+        "csrw 0xbc0, t0\n"
+    );
+}
+
+#define R32_RCC_APB2PCENR   (*(volatile uint32_t*)0x40021018)
+#define R32_GPIOA_CFGLR     (*(volatile uint32_t*)0x40010800)
+#define R32_GPIOA_BSHR      (*(volatile uint32_t*)0x40010810)
+
+int main(void) {
+    R32_RCC_APB2PCENR |= 1 << 2;
+    R32_GPIOA_CFGLR = (R32_GPIOA_CFGLR & ~0xf) | (0b0010 << 0);
+    while (1) {
+        R32_GPIOA_BSHR = 1 << 0;
+        for (int i = 0; i < 500000; i++)
+            asm volatile("");
+        R32_GPIOA_BSHR = 1 << 16;
+        for (int i = 0; i < 500000; i++)
+            asm volatile("");
+    }
+}

minimal-payload-ram/startup.S

@@ -0,0 +1,67 @@
+.section .vector,"ax",@progbits
+.align 1
+
+.global _start
+_start:
+    // Set up global pointer
+.option push
+.option norelax
+    la gp, __global_pointer$
+.option pop
+
+    // Load stack pointer
+    la sp, _eusrstack 
+
+    // Clear bss section
+    la a0, _sbss
+    la a1, _ebss
+    bgeu a0, a1, 2f
+1:
+    sw zero, (a0)
+    addi a0, a0, 4
+    bltu a0, a1, 1b
+2:
+
+    // Call preinit array functions
+    la s0, __preinit_array_start
+    la s1, __preinit_array_end
+    bgeu s0, s1, 2f
+1:
+    lw t0, (s0)
+    jalr t0
+    addi s0, s0, 4
+    bltu s0, s1, 1b
+2:
+
+    // Call init array functions
+    la s0, __init_array_start
+    la s1, __init_array_end
+    bgeu s0, s1, 2f
+1:
+    lw t0, (s0)
+    jalr t0
+    addi s0, s0, 4
+    bltu s0, s1, 1b
+2:
+
+    // Invoke main with a possible mode switch
+    la ra, 1f
+    la t0, main
+    csrw mepc, t0
+    mret
+
+1:
+    // Return from main, call fini array functions
+    la s0, __fini_array_start
+    la s1, __fini_array_end
+    bgeu s0, s1, 2f
+1:
+    lw t0, (s0)
+    jalr t0
+    addi s0, s0, 4
+    bltu s0, s1, 1b
+2:
+
+    // Finally, loop infinitely
+    wfi
+    j 2b

minimal-payload/Makefile

@@ -13,7 +13,7 @@ all: main.uf2
 main.elf: startup.o main.o
 
 %.uf2: %.bin
-	~/code/uf2/utils/uf2conv.py -f 0xdeadbeef -b 0x08002000 -o $@ $<
+	~/code/uf2/utils/uf2conv.py -c -f 0xdeadbeef -b 0x08002000 -o $@ $<
 
 %.bin: %.elf
 	$(OBJCOPY) -O binary $< $@