how to access 64bit register? only lower 32 bits are written in aarch64..

[ckim]

Hi, list members,

 

I;m faced with a problem I can’t figure out how to solve.

In a baremetal program running on aarch64, I have this test code,

 

(*(volatile uint64_t *)(AXPU_BASE + AXPU_AXEMIS_IOCTL_ARG)) = 0x99aabbccddeeff00;  // addr 0x1618

printf("read-back : cmd = %lx\n", (*(volatile uint64_t *)(AXPU_BASE + AXPU_AXEMIS_IOCTL_CMD)));

(*(volatile uint64_t *)(AXPU_BASE + AXPU_AXEMIS_IOCTL_CMD)) = 0x1122334455667788;   // addr 0x1610

printf("read-back : arg = %lx\n", (*(volatile uint64_t *)(AXPU_BASE + AXPU_AXEMIS_IOCTL_ARG)));

 

So it writes 0x99aabbccddeeff00 at offset 0x1618 first, and then write 0x1122334455667788 at 0x1610.

 

In the qemu MemoryRegionOps’s write function of the device, I added the registers with some prints and writing at IOCTL_CMD register calls a function. (this is only for a temporary test).

 

static void ab21q_axpu_write(void *opaque, hwaddr offset, uint64_t value, unsigned size)

{

printf("# size = %d\n", size);….

….

case REG_IOCTL_CMD:   // addr 0x1610

        s->ioctl_cmd = value;

        fprintf(stderr, "qemu written %lx at %lx\n", value, offset);

       //axpu_ioctl(0, value, (size_t *)s->ioctl_arg);

        break;

 

    case REG_IOCTL_ARG:    // addr 0x1618

        s->ioctl_arg = value;

        fprintf(stderr, "qemu written %lx at %lx\n", value, offset);

        break;

   ….

}

 

And this is the print from the run.

 

# size = 4

qemu written ddeeff00 at 1618

# size = 4

read-back : arg = ddeeff00

# size = 4

qemu written 55667788 at 1610

# size = 4

read-back : cmd = 55667788

 

I wanted to write two 64-bit values but it’s writing only two 32-bit values. (for the upper 32-bit values, it doesn’t write because the address mismatch – my address are only 8byte aligned) and it’s causing a problem.

Where in the qemu code should I fix so that I can write 64 bit data? And can I place 32bit registers together with 64-bit registers in a peripheral?

Any help will be deeply appreciated.

 

Thanks!

Chan Kim