From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by smtp.subspace.kernel.org (Postfix) with ESMTP id A520249BB44; Fri, 16 Oct 2026 18:27:47 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=217.140.110.172 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1792175270; cv=none; b=cuGinxC4jPnUcHpqjzE0FU8IWtdCcBgOAkcbGMhE8j6c8FCZlNlipGq7A9rlOuFxjPCFFFPU19ssJbCtUBBsRxLK1jUlB5EL2U2WJHbzF/mTZjjKYeUgWqEkhImeADhCnCGELzD6bD+3WRFLC34l7X6Lg7BtB13nmbV7gCKl/Co= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1792175270; c=relaxed/simple; bh=eXLo4l00IuxcldPkqFxylRH7Wps8yF41ZAkJADgaRHA=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=IQvDpRqi4makpq4NinMJSMgQlrfImkmCAbQ5k8nfN0nS/LgLR/ZpH+0tTOTuFS6Q78aBLybpun30lJgUJvioJPjdL1bgsVj5avcdby6gRFHaQRUre2cob6xsYUu6jCSy7lNu7hqDnSQnUMdv+kcZXH0+mupNeaP34rZNkYvu/Bs= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=arm.com; spf=pass smtp.mailfrom=arm.com; dkim=pass (1024-bit key) header.d=arm.com header.i=@arm.com header.b=U9oPvj8X; arc=none smtp.client-ip=217.140.110.172 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=arm.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=arm.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=arm.com header.i=@arm.com header.b="U9oPvj8X" Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id A92031516; Fri, 16 Oct 2026 11:27:43 -0700 (PDT) Received: from e142021.manchester.arm.com (e142021.arm.com [10.33.8.90]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 3B68B3F7B4; Fri, 16 Oct 2026 11:27:44 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=simple/simple; d=arm.com; s=foss; t=1792175266; bh=eXLo4l00IuxcldPkqFxylRH7Wps8yF41ZAkJADgaRHA=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=U9oPvj8XoObuD+WeGmW/awIze3MNcps1VBQP7WKlpK3oui9Isgen1bES+kKFi2okS iwtfuedTFUCfHN9qMuctoHYlAqfEGgk7N7vt5x/pOsY1mBa589VpGoTY95QdDTqH5R v4EUHkpwPfOKfn0uu1fmck+5VBGUkVMcceYAy6FM= From: Andre Przywara To: Mark Rutland , Lorenzo Pieralisi , Sudeep Holla Cc: Salman Nabi , Vedashree Vidwans , Trilok Soni , Nirmoy Das , vsethi@nvidia.com, Varun Wadekar , linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, Rob Herring , Krzysztof Kozlowski , Conor Dooley , devicetree@vger.kernel.org Subject: [PATCH v5 8/8] firmware: smccc: lfa: add sysfs ABI documentation Date: Fri, 16 Oct 2026 19:27:12 +0100 Message-ID: <20261016182714.1835813-9-andre.przywara@arm.com> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20261016182714.1835813-1-andre.przywara@arm.com> References: <20261016182714.1835813-1-andre.przywara@arm.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Document the sysfs attribute files as exported by the LFA driver. Signed-off-by: Andre Przywara --- Documentation/ABI/testing/sysfs-firmware-lfa | 106 +++++++++++++++++++ 1 file changed, 106 insertions(+) create mode 100644 Documentation/ABI/testing/sysfs-firmware-lfa diff --git a/Documentation/ABI/testing/sysfs-firmware-lfa b/Documentation/ABI/testing/sysfs-firmware-lfa new file mode 100644 index 0000000000000..4e93a1aea91f7 --- /dev/null +++ b/Documentation/ABI/testing/sysfs-firmware-lfa @@ -0,0 +1,106 @@ +What: /sys/firmware/lfa +Date: May 2026 +Contact: Andre Przywara +Description: + The Arm Live Firmware Activation (LFA) spec describes an + interface between platform firmware (an agent) and any user + on the non-secure side (like the Linux kernel) to activate + pending firmware updates at runtime. The actual firmware + update would be provided independently (out-of-band, or + via any existing explicit firmware update mechanism), then, + if supported, can be activated immediately, without rebooting + the system. + This directory contains one subdirectory for each of the LFA + capable firmware components supported by the agent, identified + by its UUID. Within each directory, the same set of sysfs files + provides access to the properties and actions for this + particular firmware component. + +What: /sys/firmware/lfa//activate +Date: May 2026 +Contact: Andre Przywara +Description: + (WO) Write a boolean 'true' value to trigger the + activation of that firmware component. An update must be + pending for this to be successful. + +What: /sys/firmware/lfa//activation_capable +Date: May 2026 +Contact: Andre Przywara +Description: + (RO) A boolean value to show whether this firmware component is + capable of being activated. + +What: /sys/firmware/lfa//activation_pending +Date: May 2026 +Contact: Andre Przywara +Description: + (RO) A boolean value to show whether this firmware component + has an updated image ready to be activated. + +What: /sys/firmware/lfa//auto_activate +Date: May 2026 +Contact: Andre Przywara +Description: + (RW) Write a boolean 'true' value to allow this firmware + component to be automatically activated once a new firmware + update becomes available ("pending"). This depends on a working + notification scheme, for instance via an ACPI notification + or an interrupt to notify the kernel. + +What: /sys/firmware/lfa//cancel +Date: May 2026 +Contact: Andre Przywara +Description: + (WO) Write a boolean 'true' value to cancel a recently + triggered activation, if that has not finished yet. + +What: /sys/firmware/lfa//cpu_rendezvous +Date: May 2026 +Contact: Andre Przywara +Description: + (RO) A boolean value to show whether this component requires + a CPU rendezvous in firmware to be activated. If true, this + means all CPUs will enter the firmware during the activation + process, so will not be able to execute kernel code or + handle interrupts for a brief moment. + +What: /sys/firmware/lfa//current_version +Date: May 2026 +Contact: Andre Przywara +Description: + (RO) Shows the currently running version of that firmware + component, as reported by the agent (if supported). + +What: /sys/firmware/lfa//force_cpu_rendezvous +Date: May 2026 +Contact: Andre Przywara +Description: + (RW) Write a boolean 'true' value to force whether the kernel + will perform a CPU rendezvous during activation. This has no + effect if the firmware already *requires* a CPU rendezvous. + Firmware components might provide services to the kernel, at + which point is might be unsafe to continue running the kernel + while the activation is performed. Sending all CPUs into + firmware provides the safest option for the kernel. If you know + for certain that there are no services provides by that + component or the firmware component can handle requests during + the activation, you can write a 0 in here to avoid the brief + kernel downtime. + +What: /sys/firmware/lfa//may_reset_cpu +Date: May 2026 +Contact: Andre Przywara +Description: + (RO) A boolean value to show whether this firmware component + requires a CPU reset during the activation. + Currently this type of firmware component is not supported by + the kernel driver, as we cannot handle a CPU reset. + +What: /sys/firmware/lfa//pending_version +Date: May 2026 +Contact: Andre Przywara +Description: + (RO) Shows the version number of a pending firmware update + image, as reported by the LFA agent (if supported). + If not update image is provided, this returns zero bytes. -- 2.43.0