[PATCH 3/3] bsps/shared/: Use device tree blob

[Padmarao.Begari at microchip.com]

Hi Alan,

> On Tue, 2022-09-13 at 23:57 -0400, Alan Cudmore wrote: 	
> 
> Hi Padmarao,
> I am working on a RISC-V bsp variant for the Kendryte K210 and I am
> also using an included DTB. For my k210 bsp, I changed
> riscv/shared/start/start.S to set the address of the DTB array before
> calling bsp_fdt_copy. If we change start.S to handle the following
> three cases, we would not have to change the bsp_fdt_copy function.
> The three cases are:
> - no FDT, I assume griscv bsp
> - uboot - a0 in contains the address of the u-boot loaded DTB
> - polarfire, k210 and others - set a0 to the address of the included
> DTB array
> I think it's better to keep this function generic and not have to
> conditionally ignore the input parameter.
> 

Yes, Initially I thought same but don't want to include conditional
statements in the startup code so moved to bsp_fdt_copy().

Can we try like below in the startup code? so that it can support all
three cases.

	#ifdef BSP_DTB_IS_SUPPORTED
    		#include BSP_DTB_HEADER_PATH
	#endif

	#ifdef BSP_START_COPY_FDT_FROM_U_BOOT
	#ifdef BSP_DTB_IS_SUPPORT
		LADDR a0, system_dtb
	#else
		mv	a0, a1
	#endif
		call	bsp_fdt_copy
	#endif

Regards
Padmarao

> Thanks,
> Alan
> 
> 
> On Thu, Sep 8, 2022 at 11:44 AM Padmarao Begari <
> padmarao.begari at microchip.com> wrote:
> > If the bsp is integrated and supported a device tree
> > blob(dtb) then use dtb instead of using it from the U-Boot.
> > ---
> >  bsps/shared/start/bsp-fdt.c | 11 ++++++++++-
> >  1 file changed, 10 insertions(+), 1 deletion(-)
> > 
> > diff --git a/bsps/shared/start/bsp-fdt.c b/bsps/shared/start/bsp-
> > fdt.c
> > index 75a1ea41c9..7e1a698896 100644
> > --- a/bsps/shared/start/bsp-fdt.c
> > +++ b/bsps/shared/start/bsp-fdt.c
> > @@ -32,6 +32,10 @@
> >  #include <bsp/fdt.h>
> >  #include <bsp/linker-symbols.h>
> > 
> > +#ifdef BSP_DTB_IS_SUPPORTED
> > +#include BSP_DTB_HEADER_PATH
> > +#endif
> > +
> >  #ifndef BSP_FDT_IS_SUPPORTED
> >  #warning "BSP FDT support indication not defined"
> >  #endif
> > @@ -51,7 +55,12 @@ bsp_fdt_blob[BSP_FDT_BLOB_SIZE_MAX /
> > sizeof(uint32_t)];
> > 
> >  void bsp_fdt_copy(const void *src)
> >  {
> > +#ifdef BSP_DTB_IS_SUPPORTED
> > +const volatile uint32_t *s = (const uint32_t *) system_dtb;
> > +#else
> >    const volatile uint32_t *s = (const uint32_t *) src;
> > +#endif
> > +
> >  #ifdef BSP_FDT_BLOB_COPY_TO_READ_ONLY_LOAD_AREA
> >    uint32_t *d = (uint32_t *) ((uintptr_t) &bsp_fdt_blob[0]
> >      - (uintptr_t) bsp_section_rodata_begin
> > @@ -61,7 +70,7 @@ void bsp_fdt_copy(const void *src)
> >  #endif
> > 
> >    if (s != d) {
> > -    size_t m = MIN(sizeof(bsp_fdt_blob), fdt_totalsize(src));
> > +    size_t m = MIN(sizeof(bsp_fdt_blob), fdt_totalsize(s));
> >      size_t aligned_size = roundup2(m, CPU_CACHE_LINE_BYTES);
> >      size_t n = (m + sizeof(*d) - 1) / sizeof(*d);
> >      size_t i;