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 4C4723161A3; Mon, 6 Jul 2026 13:45:30 +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=1783345534; cv=none; b=kxlz+j3GRRo46nhnXnNbM5ymQlKoPt5nQp6bnOTFR92ohg/jLvQDhT0TGR+P1t08h9y6RWCBQsPDD6WlwRfp9cEDVHpmPpV0dtdziWfPxIMEEP1Wvnme+H1/RE508YnbXN4g2oqaLTg0/e2hXV26ldz/gax666dA27t3snrboAU= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1783345534; c=relaxed/simple; bh=vWg4gUtNkdbROhbG26cNwC/fCXQrOb4eQBXyHe9MzyA=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=HByoCVlDTjdQgUMg7clT6q2m/fy+a0YbfZ/8W2Q6BwD8pMxSGJEe4Zwt01oFZkS6JfWrcDnCNZK5gv0Jv2otdeelCYzZ7GrP9H74D4JYHuwo6pYdNiPR6gIu9yDNBCx6D842pFs9AKbToYEYivTV7Ek4N2M8v24RvzIxghNC4r4= 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=hLJkwtHz; 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="hLJkwtHz" 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 2AFB232C5; Mon, 6 Jul 2026 06:45:25 -0700 (PDT) Received: from e142021.fritz.box (usa-sjc-mx-foss1.foss.arm.com [172.31.20.19]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id E95F33F7B4; Mon, 6 Jul 2026 06:45:26 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=simple/simple; d=arm.com; s=foss; t=1783345529; bh=vWg4gUtNkdbROhbG26cNwC/fCXQrOb4eQBXyHe9MzyA=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=hLJkwtHzX3LE2sw0nr9bdd13FPDF/8F4iEw7n4O8M9NEqB/yjLIowGEL6/pS3usYx OColnNZfgckwy1c20qHjcVwIHyJey3Tqk0lkTdN/awcXhlqLugkvZewpE/mMKfKWsN Cy8IeAhZdK9genE2QEj9fxNz/5FqJD2iOWVUlEKE= 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 v3 8/8] firmware: smccc: lfa: add sysfs ABI documentation Date: Mon, 6 Jul 2026 15:44:48 +0200 Message-ID: <20260706134455.132091-9-andre.przywara@arm.com> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20260706134455.132091-1-andre.przywara@arm.com> References: <20260706134455.132091-1-andre.przywara@arm.com> Precedence: bulk X-Mailing-List: devicetree@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 000000000000..afd349af9cf1 --- /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 mechanisms), then, + if supported, can be activated immediately, without rebooting + the system. + This directory contains one directory for each of the LFA + capable firmware images supported by the agent, identified by + its GUID. Within each directory, the same set of sysfs files + provides access to the properties and actions for this + particular firmware image. + +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 image is + capable of being activated. + +What: /sys/firmware/lfa//auto_activate +Date: May 2026 +Contact: Andre Przywara +Description: + (RW) Write a boolean 'true' value to allow a firmware image + 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 image 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 + image, 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 images 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 image + requires a CPU reset during the activation. + Currently this type of firmware image is not supported by + the kernel driver, as we cannot handle a CPU reset yet. + +What: /sys/firmware/lfa//name +Date: May 2026 +Contact: Andre Przywara +Description: + (RO) Shows a human readable name for that firmware image, if + known. Depends on the kernel driver knowing this particular + GUID, via a built-in list. + +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 agent (if supported). -- 2.43.0