Bare metal on Pinephone Pro - Printable Version

Bare metal on Pinephone Pro - Printable Version

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+--- Thread: Bare metal on Pinephone Pro (/showthread.php?tid=19956)

Bare metal on Pinephone Pro - alain - 08-19-2025

Hello,

I would like to boot a bare metal program (that just starts and enters in an infinite loop) (asm+c) on my ppp thank to U-Boot, but U-Boot don't boot my program and blinks the multicolor led in red, and then shut down. What's wrong in my code ?

start.S

Code:
    .global start

start:

    msr        DAIFSet, #7

    bl        main

spin:    b        spin

spl.lds

Code:
ENTRY(start)

SECTIONS

{

    . = 0x02000000;

    . = ALIGN(4);

    .text :

    {

        *(.text)

    }

    . = ALIGN(4);

    .rodata : { *(.rodata*) }

    . = ALIGN(4);

    .data : { *(.data*) }

    . = ALIGN(4);

    .got : { *(.got) }

    _end = .;

    . = ALIGN(8);

    __bss_start__ = .;

    .bss_start (OVERLAY) : {

        KEEP(*(.__bss_start));

        __bss_base = .;

    }

    .bss __bss_base (OVERLAY) : {

        *(.bss*)

        . = ALIGN(4);

        __bss_limit = .;

    }

    .bss_end __bss_limit (OVERLAY) : {

        KEEP(*(.__bss_end));

    }

    __bss_end__ = .;

}

main.c

Code:
/*

 *

 * Tom Trebisky  12-31-2021

 */

typedef volatile unsigned int vu32;

typedef unsigned int u32;

struct gpio {

    vu32 data;

    vu32 dir;

    u32 _pad0[2];

    u32 _pad1[8];

    vu32 ie;

    vu32 im;

    vu32 il;

    vu32 ip;

    vu32 is;

    vu32 ris;

    vu32 debounce;

    vu32 eoi;

    vu32 ext;

    u32 _pad2[3];

    vu32 sync;

};

#define GPIO0_BASE ((struct gpio *) 0xff720000)

#define GPIO1_BASE ((struct gpio *) 0xff730000)

#define GPIO2_BASE ((struct gpio *) 0xff780000)

#define GPIO3_BASE ((struct gpio *) 0xff788000)

#define GPIO4_BASE ((struct gpio *) 0xff790000)

#define GPIO_BASE GPIO0_BASE

#define LED_BIT        (8+3)

#define LED_PIN 24

#define LED_MASK 1<<LED_PIN

void main ( void ) {

    volatile int count = 100000000;

    while ( count-- )

        ;

}

Makefile

Code:
BOARD = rk3399

CROSS_COMPILE = aarch64-linux-gnu-

# -------------------------------------

OBJS = start.o main.o

TARGET = $(BOARD).bin

# CFLAGS        :=    -g -Wall -Wextra -ffreestanding -fno-builtin -mlittle-endian

CFLAGS        :=    -g -Wall -ffreestanding -fno-builtin -mlittle-endian

CFLAGS        += -march=armv8-a+crc

CFLAGS        += -mtune=cortex-a53

CFLAGS        += -I.

LDFLAGS        :=    -Bstatic \

            -Tspl.lds \

            -Wl,--start-group \

            -Wl,--end-group \

            -Wl,--build-id=none \

            -nostdlib

CC            =    $(CROSS_COMPILE)gcc $(CFLAGS)

LD             =    $(CROSS_COMPILE)gcc $(LDFLAGS)

OBJCOPY            =    $(CROSS_COMPILE)objcopy

DUMP            =    $(CROSS_COMPILE)objdump

LOAD            =    tools/loader -h64

# This gives us dependencies in .d files.

# CFLAGS        += -MMD

# This gives us a map file.

# CFLAGS        += -Wl,-Map=$(BOARD).map,--cref \

.c.o:

    @echo " [CC]   $<"

    @$(CC) $< -c -o $@

.S.o:

    @echo " [CC]   $<"

    @$(CC) $< -c -o $@

# -------------------------------------

all: install

#all: $(TARGET)

install: $(TARGET)

#     cp $(TARGET) /var/lib/tftpboot

$(BOARD).elf: $(OBJS)

    @echo " [LD]   $(BOARD).elf"

    @$(LD) $(OBJS) -o $(BOARD).elf

$(TARGET): $(BOARD).elf

    @#echo " [IMG]  $(TARGET)

    @$(OBJCOPY) -O binary $(BOARD).elf $(TARGET)

dis: $(BOARD).elf

    $(DUMP) -d $(BOARD).elf -z >$(BOARD).dis

fetch:

    cp ../USB_loader/loader tools

usb:  $(TARGET)

    $(LOAD) $(TARGET)

sdcard:  $(TARGET)

    $(LOAD) -o $(TARGET) | dd of=/dev/sdf seek=1 conv=fdatasync

.PHONY: clean

clean:

    rm -f *.o

    rm -f *.img

    rm -f *.elf

    rm -f *.bin

    rm -f *.map

    rm -f *.dis