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Fri, 31 Oct 2025 03:10:28 -0700 (PDT) From: adriana To: ilias.apalodimas@linaro.org, ardb@kernel.org, trini@konsulko.com Cc: robh@kernel.org, krzk@kernel.org, jdelvare@suse.com, frowand.list@gmail.com, linux-kernel@vger.kernel.org, devicetree@vger.kernel.org, vasilykh@arista.com, arm.ebbr-discuss@arm.com, boot-architecture@lists.linaro.org, linux-efi@vger.kernel.org, uefi-discuss@lists.uefi.org, linux-arm-kernel@lists.infradead.org, adriana Subject: [PATCH v4 1/2] dt-bindings: firmware: Add binding for SMBIOS /chosen properties Date: Fri, 31 Oct 2025 03:10:08 -0700 Message-ID: <20251031101009.704759-2-adriana@arista.com> X-Mailer: git-send-email 2.51.0 In-Reply-To: <20251031101009.704759-1-adriana@arista.com> References: <20251031084101.701159-1-adriana@arista.com> <20251031101009.704759-1-adriana@arista.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" Signed-off-by: adriana Reviewed-by: Ard Biesheuvel Reviewed-by: Ilias Apalodimas --- .../firmware/linux,smbios3-entrypoint.yaml | 25 +++++++++++++++++++ 1 file changed, 25 insertions(+) create mode 100644 Documentation/devicetree/bindings/firmware/linux,smbios= 3-entrypoint.yaml diff --git a/Documentation/devicetree/bindings/firmware/linux,smbios3-entry= point.yaml b/Documentation/devicetree/bindings/firmware/linux,smbios3-entry= point.yaml new file mode 100644 index 000000000000..4d1521c685ff --- /dev/null +++ b/Documentation/devicetree/bindings/firmware/linux,smbios3-entrypoint.y= aml @@ -0,0 +1,25 @@ +# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause) +# Copyright 2025 Arista Networks +%YAML 1.2 +--- +$id: http://devicetree.org/schemas/firmware/linux,smbios3-entrypoint.yaml# +$schema: http://devicetree.org/meta-schemas/core.yaml# + +title: Memory location for SMBIOS entry point=20 + +description: | + This property is used in the /chosen node to pass the physical address + of SMBIOS (System Management BIOS) or DMI (Desktop Management Interface) + tables from firmware to the kernel. This is typically used on non-EFI. + =20 +maintainers: + - Adriana Nicolae + - Rob Herring + +properties: + linux,smbios3-entrypoint: + $ref: /schemas/types.yaml#/definitions/uint64 + description: + The 64-bit physical address of the SMBIOSv3 entry point structure. + +additionalProperties: true --=20 2.51.0 From nobody Sun Feb 8 14:22:28 2026 Received: from mail-pl1-f180.google.com (mail-pl1-f180.google.com [209.85.214.180]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 34303332EAF for ; Fri, 31 Oct 2025 10:10:33 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.214.180 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1761905438; cv=none; b=bccvDJaCB0Tp00ujcpGb0LAubRjAedMGJPmp1YihfG7u59ij3gbhrS5z9+8t5NsOvpSe1FX/MH2jPGm1+9VRYQoNJCb9KL8fVP0FpEtNmTZXCfmn+7kKCRdtDJY6uJ4WSQpzBiZ11jtQnh/UbxCJMepAXWEd0FqOiufx+3BBMms= ARC-Message-Signature: i=1; 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Fri, 31 Oct 2025 03:10:30 -0700 (PDT) Received: from adriana-dmi-upstream.sjc.aristanetworks.com ([74.123.28.20]) by smtp.gmail.com with ESMTPSA id d9443c01a7336-2952774570bsm17458545ad.99.2025.10.31.03.10.29 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 31 Oct 2025 03:10:30 -0700 (PDT) From: adriana To: ilias.apalodimas@linaro.org, ardb@kernel.org, trini@konsulko.com Cc: robh@kernel.org, krzk@kernel.org, jdelvare@suse.com, frowand.list@gmail.com, linux-kernel@vger.kernel.org, devicetree@vger.kernel.org, vasilykh@arista.com, arm.ebbr-discuss@arm.com, boot-architecture@lists.linaro.org, linux-efi@vger.kernel.org, uefi-discuss@lists.uefi.org, linux-arm-kernel@lists.infradead.org, adriana Subject: [PATCH v4 2/2] drivers: firmware: dmi_scan: Add support for reading SMBIOS from DT Date: Fri, 31 Oct 2025 03:10:09 -0700 Message-ID: <20251031101009.704759-3-adriana@arista.com> X-Mailer: git-send-email 2.51.0 In-Reply-To: <20251031101009.704759-1-adriana@arista.com> References: <20251031084101.701159-1-adriana@arista.com> <20251031101009.704759-1-adriana@arista.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" Some bootloaders provide SMBIOS/DMI tables at a specific memory address, particularly on non-EFI ARM platforms. The kernel's standard EFI DMI scanner cannot find these tables. This patch adds a fallback mechanism to the DMI scanner to read the physical address of the SMBIOS3 entry point from the device tree. This scan is performed only if the standard EFI check fails. Signed-off-by: adriana Reviewed-by: Ard Biesheuvel Reviewed-by: Ilias Apalodimas --- drivers/firmware/dmi_scan.c | 54 +++++++++++++++++++++++++++++++++++++ 1 file changed, 54 insertions(+) diff --git a/drivers/firmware/dmi_scan.c b/drivers/firmware/dmi_scan.c index 70d39adf50dc..c29ca98f09b5 100644 --- a/drivers/firmware/dmi_scan.c +++ b/drivers/firmware/dmi_scan.c @@ -10,10 +10,12 @@ #include #include #include +#include =20 #ifndef SMBIOS_ENTRY_POINT_SCAN_START #define SMBIOS_ENTRY_POINT_SCAN_START 0xF0000 #endif +#define SMBIOS3_ENTRY_POINT_SIZE 32 =20 struct kobject *dmi_kobj; EXPORT_SYMBOL_GPL(dmi_kobj); @@ -670,6 +672,51 @@ static int __init dmi_smbios3_present(const u8 *buf) return 1; } =20 +/** + * dmi_scan_from_dt - Find SMBIOS3 entrypoint address via Device Tree + * + * Checks if the bootloader has passed the physical address of the + * SMBIOS3 entrypoint structure via the "linux,smbios3-entrypoint" + * property in the /chosen node. + * Returns true if a valid entrypoint is found. + */ +static bool __init dmi_scan_from_dt(void) +{ + struct device_node *chosen; + const __be64 *prop; + char buf[SMBIOS3_ENTRY_POINT_SIZE]; + void __iomem *p; + bool dmi_available =3D false; + u64 addr; + int len; + + if(!IS_ENABLED(CONFIG_OF)) + return false; + + chosen =3D of_find_node_by_path("/chosen"); + if (!chosen) + return false; + + prop =3D of_get_property(chosen, "linux,smbios3-entrypoint", &len); + if (prop && len >=3D sizeof(u64)) { + addr =3D be64_to_cpup(prop); + + p =3D dmi_early_remap(addr, SMBIOS3_ENTRY_POINT_SIZE); + if (!p) + goto out; + + memcpy_fromio(buf, p, sizeof(buf)); + dmi_early_unmap(p, SMBIOS3_ENTRY_POINT_SIZE); + + if (!dmi_smbios3_present(buf)) + dmi_available =3D true; + } + +out: + of_node_put(chosen); + return dmi_available; +} + static void __init dmi_scan_machine(void) { char __iomem *p, *q; @@ -718,6 +765,13 @@ static void __init dmi_scan_machine(void) dmi_available =3D 1; return; } + } else if (dmi_scan_from_dt()) { + /* + * If EFI is not present or failed, try getting SMBIOS3 + * entrypoint from the Device Tree. + */ + dmi_available =3D 1; + return; } else if (IS_ENABLED(CONFIG_DMI_SCAN_MACHINE_NON_EFI_FALLBACK)) { p =3D dmi_early_remap(SMBIOS_ENTRY_POINT_SCAN_START, 0x10000); if (p =3D=3D NULL) --=20 2.51.0