Re: [PATCH 04/11] ARM: i.MX8MQ: Add a macro to load BL31 ATF blob

[Andrey Smirnov <andrew.smirnov@gmail.com>]

On Tue, Jul 3, 2018 at 10:58 AM Andrey Smirnov <andrew.smirnov@gmail.com> wrote:
>
> On Sun, Jul 1, 2018 at 11:25 PM Sascha Hauer <s.hauer@pengutronix.de> wrote:
> >
> > On Fri, Jun 29, 2018 at 08:48:53PM -0700, Andrey Smirnov wrote:
> > > Add a macro containing all of the code needed to load and transfer
> > > control to BL31 ATF blob on i.MX8M.
> > >
> > > Signed-off-by: Andrey Smirnov <andrew.smirnov@gmail.com>
> > > ---
> > >  arch/arm/mach-imx/include/mach/atf.h | 63 ++++++++++++++++++++++++++++
> > >  1 file changed, 63 insertions(+)
> > >  create mode 100644 arch/arm/mach-imx/include/mach/atf.h
> > >
> > > diff --git a/arch/arm/mach-imx/include/mach/atf.h b/arch/arm/mach-imx/include/mach/atf.h
> > > new file mode 100644
> > > index 000000000..0b5018459
> > > --- /dev/null
> > > +++ b/arch/arm/mach-imx/include/mach/atf.h
> > > @@ -0,0 +1,63 @@
> > > +#ifndef __IMX_ATF_H__
> > > +#define __IMX_ATF_H__
> > > +
> > > +#include <asm/system.h>
> > > +
> > > +#define MX8MQ_ATF_BL31_SIZE_LIMIT    SZ_64K
> > > +#define MX8MQ_ATF_BL31_BASE_ADDR     0x00910000
> > > +#define MX8MQ_ATF_BL33_BASE_ADDR     0x40200000
> > > +
> > > +/**
> > > + * imx8mq_atf_load_bl31 - Load ATF BL31 blob and transfer contol to it
> > > + *
> > > + * @name:    Name of the BL31 blob
> > > + *
> > > + * This macro:
> > > +
> > > + *     1. Copies built-in BL31 blob to an address i.MX8M's BL31
> > > + *        expects to be placed
> > > + *
> > > + *     2. Sets up temporary stack pointer for EL2, which is execution
> > > + *        level that BL31 will drop us off at after it completes its
> > > + *        initialization routine
> > > + *
> > > + *     3. Transfers control to BL31
> > > + *
> > > + * NOTE: This has to be a macro in order delay the expansion of
> > > + * get_builtin_firmware(), otherwise it'll incorrectly interpret
> > > + * "name" literally
> >
> > You show a good reason why we should add the firmware name strings
> > to the image along with a function that iterates over them. How
> > to add the firmware name strings is already provided in the Kernels
> > firmware/Makefile.
> >
>
> OK, makes sense. I'll work on adding that feature as a part of v2.
>

Hmm, I just realized two things:

    - Implementing that besides porting a bunch of code would require
early relocation, which I really would like to avoid

    - We can convert imx8mq_atf_load_bl31() into a function if we
change its signature to accept a blob pointer and blob size. And leave
it up to the user as to how that blob is obtained.

Given the first and simplicity of the second, I think I am going to go
that way for v2.

Thanks,
Andrey Smirnov

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