[PATCH 2/2] ARM: rpi_b: use bcm2835 mbox driver to get memory size

[Albert ARIBAUD]

Hi Stephen,

On Mon, 15 Oct 2012 23:10:36 -0600, Stephen Warren
<swarren at wwwdotorg.org> wrote:

> The firmware running on the bcm2835 SoC's VideoCore CPU determines how
> much of the system RAM is available for use by the ARM CPU. Previously,
> U-Boot assumed that only 128MB was available, since this was the
> smallest value configured by any public firmware. However, we can now
> query the actual value at run-time from the firmware using the mbox
> property protocol.
> 
> Signed-off-by: Stephen Warren <swarren at wwwdotorg.org>
> ---
>  board/raspberrypi/rpi_b/rpi_b.c |   20 +++++++++++++++++++-
>  1 file changed, 19 insertions(+), 1 deletion(-)
> 
> diff --git a/board/raspberrypi/rpi_b/rpi_b.c b/board/raspberrypi/rpi_b/rpi_b.c
> index 688b0aa..88f8c58 100644
> --- a/board/raspberrypi/rpi_b/rpi_b.c
> +++ b/board/raspberrypi/rpi_b/rpi_b.c
> @@ -15,13 +15,31 @@
>   */
>  
>  #include <common.h>
> +#include <asm/arch/mbox.h>
>  #include <asm/global_data.h>
>  
>  DECLARE_GLOBAL_DATA_PTR;
>  
>  int dram_init(void)
>  {
> -	gd->ram_size = CONFIG_SYS_SDRAM_SIZE;
> +	ALLOC_ALIGN_BUFFER(struct bcm2835_mbox_buf_get_arm_mem, buf, 1, 16);
> +
> +	memset(buf, 0, sizeof(*buf));
> +	buf->hdr.buf_size = sizeof(*buf);
> +	buf->hdr.code = BCM2835_MBOX_REQ_CODE;
> +	buf->tag_hdr.tag = BCM2835_MBOX_TAG_GET_ARM_MEMORY;
> +	buf->tag_hdr.val_buf_size = sizeof(buf->body);
> +	buf->tag_hdr.val_len = sizeof(buf->body.req);
> +
> +	bcm2835_mbox_call_prop(BCM2835_MBOX_PROP_CHAN, &buf->hdr);
> +
> +	if ((buf->hdr.code != BCM2835_MBOX_RESP_CODE_SUCCESS) ||
> +	    (!(buf->tag_hdr.val_len & BCM2835_MBOX_TAG_VAL_LEN_RESPONSE))) {
> +		printf("BCM2835_MBOX_TAG_GET_ARM_MEMORY failed\n");
> +		return -1;
> +	}
> +
> +	gd->ram_size = buf->body.resp.mem_size;
>  
>  	return 0;
>  }

Either move the buffer processing into mbox (as an opaque "ask mbox for
memory size" function) or move the memory request struct in here (this
is in order to have a self-consistent mbox interface where either the
mbox API does not know at all about the mem size request, or it knows
all about it).

Amicalement,
-- 
Albert.