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Date:   Tue, 21 Apr 2020 12:19:38 -0700 (PDT)
Subject:     Re: [v2 PATCH 3/5] RISC-V: Define fixmap bindings for generic early ioremap support
In-Reply-To: <20200413212907.29244-4-atish.patra@wdc.com>
CC:     linux-kernel@vger.kernel.org, Atish Patra <Atish.Patra@wdc.com>,
        ardb@kernel.org, Arnd Bergmann <arnd@arndb.de>,
        catalin.marinas@arm.com, Greg KH <gregkh@linuxfoundation.org>,
        mingo@kernel.org, linux-efi@vger.kernel.org,
        linux-riscv@lists.infradead.org,
        linux-arm-kernel@lists.infradead.org, masahiroy@kernel.org,
        linux@armlinux.org.uk, will@kernel.org
From:   Palmer Dabbelt <palmer@dabbelt.com>
To:     Atish Patra <Atish.Patra@wdc.com>
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On Mon, 13 Apr 2020 14:29:05 PDT (-0700), Atish Patra 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>
> Acked-by: Ard Biesheuvel <ardb@kernel.org>
> ---
>  arch/riscv/Kconfig              |  1 +
>  arch/riscv/include/asm/Kbuild   |  1 +
>  arch/riscv/include/asm/fixmap.h | 18 ++++++++++++++++++
>  arch/riscv/include/asm/io.h     |  1 +
>  4 files changed, 21 insertions(+)
>
> diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig
> index a197258595ef..f39e326a7a42 100644
> --- a/arch/riscv/Kconfig
> +++ b/arch/riscv/Kconfig
> @@ -68,6 +68,7 @@ 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 3d9410bb4de0..59dd7be55005 100644
> --- a/arch/riscv/include/asm/Kbuild
> +++ b/arch/riscv/include/asm/Kbuild
> @@ -1,4 +1,5 @@
>  # SPDX-License-Identifier: GPL-2.0
> +generic-y += early_ioremap.h
>  generic-y += extable.h
>  generic-y += flat.h
>  generic-y += kvm_para.h
> diff --git a/arch/riscv/include/asm/fixmap.h b/arch/riscv/include/asm/fixmap.h
> index 2368d49eb4ef..ba5096d65fb0 100644
> --- a/arch/riscv/include/asm/fixmap.h
> +++ b/arch/riscv/include/asm/fixmap.h
> @@ -30,6 +30,24 @@ enum fixed_addresses {
>  	FIX_TEXT_POKE1,
>  	FIX_TEXT_POKE0,
>  	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

Reviewed-by: Palmer Dabbelt <palmerdabbelt@google.com>