From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 25688CD6E4A for ; Thu, 4 Jun 2026 12:59:12 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:List-Subscribe:List-Help :List-Post:List-Archive:List-Unsubscribe:List-Id:Content-Type:MIME-Version: Message-ID:Date:References:In-Reply-To:Subject:Cc:To:From:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=ns6EOiv/DbO2oyNf7BQsADHvEVxuPqFiM2RPQ8DKZeY=; b=sXd2CBorS4pw0sbxIEhbhX6q7X KIikFb98LkGTeqJYa6e1UJTHWWQpqyPCSG1I2WiqiRctQ3DKqH3li/o8ljdxPjhb7tav/+4VGPL8f jwfdO4RLOfLpmbLqLsf0GERFC6kDHgau6jh7Vh7k9R4nI6IOvPbgTwQTApx9vZtlZDmMYLU0+WcWG Pg71fN+xLrPFJ/oBH7gHSWT0E3evMxqEpyWkkoZ2KumY0VL56X/EJGeVOkuFL1DrLgpsCa/WIC+Bz Ky9GwB9zfaK+H55GfgNrjysnBvrlUKwfTMLItKM/rTc9dq738c2eTyNTnjrIIIc0BcbA3H3jaXA91 ppOrEYxg==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.99.1 #2 (Red Hat Linux)) id 1wV7f6-0000000Gkfu-1dkT; Thu, 04 Jun 2026 12:59:04 +0000 Received: from sea.source.kernel.org ([2600:3c0a:e001:78e:0:1991:8:25]) by bombadil.infradead.org with esmtps (Exim 4.99.1 #2 (Red Hat Linux)) id 1wV7f5-0000000Gkfo-1PDL for linux-arm-kernel@lists.infradead.org; Thu, 04 Jun 2026 12:59:03 +0000 Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) by sea.source.kernel.org (Postfix) with ESMTP id ACCD5400B6; Thu, 4 Jun 2026 12:59:02 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 1F6231F00893; Thu, 4 Jun 2026 12:58:57 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1780577942; bh=ns6EOiv/DbO2oyNf7BQsADHvEVxuPqFiM2RPQ8DKZeY=; h=From:To:Cc:Subject:In-Reply-To:References:Date; b=BEbFpXybcDnZt90rF1wHgq0+lDe5SGsffyAP9HouNZYlR/6fmN9ghOtswpIcmXhlQ GeTq8s/B32fY8atHayl/nczGINGnHSlBiSHTSZc0y6DjJZirhd5lJDUF4NjmSVvjPv /NvOUHqxu3cPrJLAzXoyk3Gm9c/4fj+ag7FZanFRg0KWZzp6aH8wYpDno/I7efHozt J/12RRLCaSuupTwxWP0eNNYFBJuaoioRwgGnZEpqtL5e4SxHL147nwFiv3qvZ2yJ1/ oTw0Zkk4uzvAcHeAL2N1BOnomgYVfWL4ZpcTFC/n7ZXV0zk8zS04q5wRRIY6rCt4PW NnNML3iCU7Tag== X-Mailer: emacs 30.2 (via feedmail 11-beta-1 I) From: Aneesh Kumar K.V To: gregkh@linuxfounation.org, linux-coco@lists.linux.dev, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org Cc: Catalin Marinas , Jeremy Linton , Jonathan Cameron , Lorenzo Pieralisi , Mark Rutland , Sudeep Holla , Will Deacon , Steven Price , Suzuki K Poulose Subject: Re: [PATCH v6 0/4] Switch Arm SMCCC firmware services to an SMCCC bus In-Reply-To: <20260527100233.428018-1-aneesh.kumar@kernel.org> References: <20260527100233.428018-1-aneesh.kumar@kernel.org> Date: Thu, 04 Jun 2026 18:28:54 +0530 Message-ID: MIME-Version: 1.0 Content-Type: text/plain X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org Hi Greg, "Aneesh Kumar K.V (Arm)" writes: > As discussed here: > https://lore.kernel.org/all/20250728135216.48084-12-aneesh.kumar@kernel.org > > The earlier CCA guest support used an arm-cca-dev platform device as a pure > software anchor for the TSM class device. That platform device did not > correspond to a DT/ACPI described device, MMIO range, interrupt, or other > platform resource; it existed only to make the CCA guest driver bind and to > place the resulting TSM device in the driver model. The same pattern also > exists for smccc_trng. Creating separate platform devices for such > SMCCC-discovered features is misleading, because those features are not > independent platform devices. > > This series adds an Arm SMCCC bus for services discovered through the SMCCC > firmware interface. The bus provides SMCCC device and driver registration > helpers, name-based matching, uevent modalias generation, and a sysfs modalias > attribute. SMCCC service drivers can use MODULE_DEVICE_TABLE(arm_smccc, ...) > to emit arm_smccc: aliases, allowing userspace to autoload service > drivers when the SMCCC core registers matching firmware-service devices. > > The series then moves SMCCC TRNG and the Arm CCA guest RSI service off the > platform bus. When the SMCCC core discovers the corresponding firmware > service, it registers an arm-smccc device for that service. The hwrng > arm_smccc_trng driver and the Arm CCA guest TSM provider are converted to > SMCCC drivers that bind to those discovered devices. > > The old arm-cca-dev platform device has also been used by userspace as a Realm > guest indicator. Removing it without a replacement would leave userspace > depending on an internal driver-binding device. This series therefore adds > /sys/firmware/cca/realm_guest as a stable, architecture-provided ABI for > detecting whether the kernel is running as an Arm CCA Realm guest, and then > removes the dummy arm-cca-dev platform-device registration. > Gentle ping. Based on your feedback in [1], I reworked the series to use an SMCCC bus, with smccc-trng and arm-cca-dev represented as devices on that bus. Could you let me know whether this approach addresses your concerns? [1] https://lore.kernel.org/all/2026051451-comfort-museum-4d2a@gregkh/ -aneesh