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From:   Ard Biesheuvel <ardb@kernel.org>
Date:   Wed, 26 Feb 2020 08:08:50 +0100
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Subject: Re: [RFC PATCH 3/5] RISC-V: Define fixmap bindings for generic early
 ioremap support
To:     Atish Patra <atish.patra@wdc.com>
Cc:     Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        Albert Ou <aou@eecs.berkeley.edu>,
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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?

> ---
>  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
>