Re: [RFC PATCH 3/5] RISC-V: Define fixmap bindings for generic early ioremap support

[Atish Patra <Atish.Patra@wdc.com>]

On Wed, 2020-02-26 at 08:08 +0100, Ard Biesheuvel wrote:
> On Wed, 26 Feb 2020 at 02:10, Atish Patra <atish.patra@wdc.com>
> wrote:
> > UEFI uses early IO or memory mappings for runtime services before
> > normal ioremap() is usable. This patch only adds minimum necessary
> > fixmap bindings and headers for generic ioremap support to work.
> > 
> > Signed-off-by: Atish Patra <atish.patra@wdc.com>
> 
> Looks reasonable to me,
> 
> Acked-by: Ard Biesheuvel <ardb@kernel.org>
> 
> although I wonder why it is part of this series?
> 

because of CONFIG_EFI. With CONFIG_EFI enabled, all the run time
service memory mapping code is compiled for RISC-V. I could have
createa a separate config for only boot time services or used EFI_STUB
at places where CONFI_EFI. But it seems redundant as we will support
runtime services soon. Let me know if that's a wrong approach.

> > ---
> >  arch/riscv/Kconfig              |  1 +
> >  arch/riscv/include/asm/Kbuild   |  1 +
> >  arch/riscv/include/asm/fixmap.h | 21 ++++++++++++++++++++-
> >  arch/riscv/include/asm/io.h     |  1 +
> >  4 files changed, 23 insertions(+), 1 deletion(-)
> > 
> > diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig
> > index 27bfc7947e44..42c122170cfd 100644
> > --- a/arch/riscv/Kconfig
> > +++ b/arch/riscv/Kconfig
> > @@ -65,6 +65,7 @@ config RISCV
> >         select ARCH_HAS_GCOV_PROFILE_ALL
> >         select HAVE_COPY_THREAD_TLS
> >         select HAVE_ARCH_KASAN if MMU && 64BIT
> > +       select GENERIC_EARLY_IOREMAP
> > 
> >  config ARCH_MMAP_RND_BITS_MIN
> >         default 18 if 64BIT
> > diff --git a/arch/riscv/include/asm/Kbuild
> > b/arch/riscv/include/asm/Kbuild
> > index ec0ca8c6ab64..517394390106 100644
> > --- a/arch/riscv/include/asm/Kbuild
> > +++ b/arch/riscv/include/asm/Kbuild
> > @@ -4,6 +4,7 @@ generic-y += checksum.h
> >  generic-y += compat.h
> >  generic-y += device.h
> >  generic-y += div64.h
> > +generic-y += early_ioremap.h
> >  generic-y += extable.h
> >  generic-y += flat.h
> >  generic-y += dma.h
> > diff --git a/arch/riscv/include/asm/fixmap.h
> > b/arch/riscv/include/asm/fixmap.h
> > index 42d2c42f3cc9..7a4beb7e29a3 100644
> > --- a/arch/riscv/include/asm/fixmap.h
> > +++ b/arch/riscv/include/asm/fixmap.h
> > @@ -25,9 +25,28 @@ enum fixed_addresses {
> >  #define FIX_FDT_SIZE   SZ_1M
> >         FIX_FDT_END,
> >         FIX_FDT = FIX_FDT_END + FIX_FDT_SIZE / PAGE_SIZE - 1,
> > +       FIX_EARLYCON_MEM_BASE,
> > +
> >         FIX_PTE,
> >         FIX_PMD,
> > -       FIX_EARLYCON_MEM_BASE,
> > +       /*
> > +        * Make sure that it is 2MB aligned.
> > +        */
> > +#define NR_FIX_SZ_2M   (SZ_2M / PAGE_SIZE)
> > +       FIX_THOLE = NR_FIX_SZ_2M - FIX_PMD - 1,
> > +
> > +       __end_of_permanent_fixed_addresses,
> > +       /*
> > +        * Temporary boot-time mappings, used by early_ioremap(),
> > +        * before ioremap() is functional.
> > +        */
> > +#define NR_FIX_BTMAPS          (SZ_256K / PAGE_SIZE)
> > +#define FIX_BTMAPS_SLOTS       7
> > +#define TOTAL_FIX_BTMAPS       (NR_FIX_BTMAPS * FIX_BTMAPS_SLOTS)
> > +
> > +       FIX_BTMAP_END = __end_of_permanent_fixed_addresses,
> > +       FIX_BTMAP_BEGIN = FIX_BTMAP_END + TOTAL_FIX_BTMAPS - 1,
> > +
> >         __end_of_fixed_addresses
> >  };
> > 
> > diff --git a/arch/riscv/include/asm/io.h
> > b/arch/riscv/include/asm/io.h
> > index 0f477206a4ed..047f414b6948 100644
> > --- a/arch/riscv/include/asm/io.h
> > +++ b/arch/riscv/include/asm/io.h
> > @@ -14,6 +14,7 @@
> >  #include <linux/types.h>
> >  #include <asm/mmiowb.h>
> >  #include <asm/pgtable.h>
> > +#include <asm/early_ioremap.h>
> > 
> >  /*
> >   * MMIO access functions are separated out to break dependency
> > cycles
> > --
> > 2.24.0
> > 

-- 
Regards,
Atish