[PATCH 1/3] spl: fit: Minimally parse OS properties with FIT_IMAGE_TINY

[Patrick Wildt]

On Thu, May 07, 2020 at 06:20:33PM -0500, Samuel Holland wrote:
> Some boards, specifically 64-bit Allwinner boards (sun50i), are
> extremely limited on SPL size. One strategy that was used to make space
> was to remove the FIT "os" property parsing code, because it uses a
> rather large lookup table.
> 
> However, this forces the legacy FIT parsing code path, which requires
> the "firmware" entry in the FIT to reference the U-Boot binary, even if
> U-Boot is not the next binary in the boot sequence (for example, on
> sun50i boards, ATF is run first).
> 
> This prevents the same FIT image from being used with a SPL with
> CONFIG_SPL_FIT_IMAGE_TINY=n and CONFIG_SPL_ATF=y, because the boot
> method selection code looks at `spl_image.os`, which is only set from
> the "firmware" entry's "os" property.
> 
> To be able to use CONFIG_SPL_ATF=y, the "firmware" entry in the FIT
> must be ATF, and U-Boot must be a loadable. For this to work, we need to
> parse the "os" property just enough to tell U-Boot from other images, so
> we can find it in the loadables list to append the FDT, and so we don't
> try to append the FDT to ATF (which could clobber adjacent firmware).
> 
> So add the minimal code necessary to distinguish U-Boot/non-U-Boot
> loadables with CONFIG_SPL_FIT_IMAGE_TINY=y. This adds about 300 bytes,
> much less than the 7400 bytes added by CONFIG_SPL_FIT_IMAGE_TINY=n.
> 
> Signed-off-by: Samuel Holland <samuel at sholland.org>

Acked-by: Patrick Wildt <patrick at blueri.se>

> ---
>  common/spl/Kconfig   |  4 +---
>  common/spl/spl_fit.c | 17 ++++++++++++++++-
>  2 files changed, 17 insertions(+), 4 deletions(-)
> 
> diff --git a/common/spl/Kconfig b/common/spl/Kconfig
> index 9feadb5e43..f2fa12354d 100644
> --- a/common/spl/Kconfig
> +++ b/common/spl/Kconfig
> @@ -448,9 +448,7 @@ config SPL_FIT_IMAGE_TINY
>  	  Enable this to reduce the size of the FIT image loading code
>  	  in SPL, if space for the SPL binary is very tight.
>  
> -	  This removes the detection of image types (which forces the
> -	  first image to be treated as having a U-Boot style calling
> -	  convention) and skips the recording of each loaded payload
> +	  This skips the recording of each loaded payload
>  	  (i.e. loadable) into the FDT (modifying the loaded FDT to
>  	  ensure this information is available to the next image
>  	  invoked).
> diff --git a/common/spl/spl_fit.c b/common/spl/spl_fit.c
> index c51e4beb1c..b9dd4211aa 100644
> --- a/common/spl/spl_fit.c
> +++ b/common/spl/spl_fit.c
> @@ -464,7 +464,22 @@ static int spl_fit_record_loadable(const void *fit, int images, int index,
>  static int spl_fit_image_get_os(const void *fit, int noffset, uint8_t *os)
>  {
>  #if CONFIG_IS_ENABLED(FIT_IMAGE_TINY) && !defined(CONFIG_SPL_OS_BOOT)
> -	return -ENOTSUPP;
> +	const char *name = fdt_getprop(fit, noffset, FIT_OS_PROP, NULL);
> +
> +	if (!name)
> +		return -ENOENT;
> +
> +	/*
> +	 * We don't care what the type of the image actually is,
> +	 * only whether or not it is U-Boot. This saves some
> +	 * space by omitting the large table of OS types.
> +	 */
> +	if (!strcmp(name, "u-boot"))
> +		*os = IH_OS_U_BOOT;
> +	else
> +		*os = IH_OS_INVALID;
> +
> +	return 0;
>  #else
>  	return fit_image_get_os(fit, noffset, os);
>  #endif
> -- 
> 2.24.1
>