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 X-Spam-Level: X-Spam-Status: No, score=-0.8 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 62D6AC432C3 for ; Mon, 2 Dec 2019 16:12:20 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 36AB52053B for ; Mon, 2 Dec 2019 16:12:20 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=linaro.org header.i=@linaro.org header.b="ig1O7d6G" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727484AbfLBQMR (ORCPT ); Mon, 2 Dec 2019 11:12:17 -0500 Received: from mail-wr1-f67.google.com ([209.85.221.67]:43798 "EHLO mail-wr1-f67.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727471AbfLBQMR (ORCPT ); Mon, 2 Dec 2019 11:12:17 -0500 Received: by mail-wr1-f67.google.com with SMTP id n1so45041802wra.10 for ; Mon, 02 Dec 2019 08:12:15 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linaro.org; s=google; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=7Xv8o+WsUdwWC7CiaXpsHd5QUxK044+HKFw9W9npptk=; b=ig1O7d6GsDt4NBwP75X4Y5ujFXKgklak77SWNGcBuqnwXLGpk+P5XN90JKiEaf2DlT WrVdXQtvxPygQzaAZx5Wyn09al6SJ3AefSjaSRjKH65+vqyjjGV3AAI7blYUMk6bxxNU imZoAbvk8e7WIQaP2QJWb/dcdykPO0gubpktQ7rXHibDskvWbSc6e4RfKGeymd1SEHkQ rN4NCNH9RCYgSR8vJIq6oJKWcWEeRYOub/IGzL0nHFyW8U+kqcHiSk1Jtzj7DgCmQ2b1 6mAr45FJYKlH47wLqjdCfiLeG38To+D9j+tZ1HBGdU1DBkzyDaikMHe5JMWjDCUZBREU +AIw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=7Xv8o+WsUdwWC7CiaXpsHd5QUxK044+HKFw9W9npptk=; b=OhymhxdQoSTOwP9IJAjh/ihIavVzESWk8yC/LwEcmSOUgpjh5nG7uph2O+mP7St2xz GD9gUjzhjUPXPfIfJz40sWCmalpmhTw5eX9kXPHGZrmKKqbzGsjxWbpfgoRe5pT3j2sl bYWYe4NeZaZBnNK5jDUmT5BPlH6lnam9jXtN5sZS7Ibqw7hGxdACMlLCLbX2pnJmJCx1 8NnAaEVqKFuYVshOpAMuAby6gi3+xvMWubAZfGsnp92LDj9KrraqMn8141gmElX00TqM 2DLul2GFMw0mVkYf8e0Jl9HXKT66URkmfDdz1mBKQakLU94jTkaaE8Hi8nZ7ebzMbEza GY0A== X-Gm-Message-State: APjAAAVYayMmX4e9WTz9cRq3F+6RPbT+KvIFS8Cb95qWS/NxrlOdErE4 AnANIS8FNGMZ/FisJ93OII5493eJ9pe+0gY+g1V4tg== X-Google-Smtp-Source: APXvYqxqte31rdFQPjtRI2d0z8l6rqekmUjNbkTYkhGQNfoYXbCoNDt/WGK3fQmslUDfdpQIN0cF13ot7mHRN/DXrE0= X-Received: by 2002:a5d:5345:: with SMTP id t5mr34600649wrv.0.1575303135165; Mon, 02 Dec 2019 08:12:15 -0800 (PST) MIME-Version: 1.0 References: <1574864578-467-1-git-send-email-neal.liu@mediatek.com> <1574864578-467-4-git-send-email-neal.liu@mediatek.com> <1575027046.24848.4.camel@mtkswgap22> In-Reply-To: <1575027046.24848.4.camel@mtkswgap22> From: Ard Biesheuvel Date: Mon, 2 Dec 2019 16:12:09 +0000 Message-ID: Subject: Re: [PATCH v5 3/3] hwrng: add mtk-sec-rng driver To: Neal Liu , Catalin Marinas , Will Deacon , Marc Zyngier Cc: Lars Persson , Mark Rutland , DTML , Herbert Xu , wsd_upstream , Sean Wang , Linux Kernel Mailing List , Rob Herring , =?UTF-8?B?Q3J5c3RhbCBHdW8gKOmDreaZtik=?= , "linux-crypto@vger.kernel.org" , Matt Mackall , Matthias Brugger , "linux-mediatek@lists.infradead.org" , "linux-arm-kernel@lists.infradead.org" Content-Type: text/plain; charset="UTF-8" Sender: devicetree-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: devicetree@vger.kernel.org (adding some more arm64 folks) On Fri, 29 Nov 2019 at 11:30, Neal Liu wrote: > > On Fri, 2019-11-29 at 18:02 +0800, Lars Persson wrote: > > Hi Neal, > > > > On Wed, Nov 27, 2019 at 3:23 PM Neal Liu wrote: > > > > > > For MediaTek SoCs on ARMv8 with TrustZone enabled, peripherals like > > > entropy sources is not accessible from normal world (linux) and > > > rather accessible from secure world (ATF/TEE) only. This driver aims > > > to provide a generic interface to ATF rng service. > > > > > > > I am working on several SoCs that also will need this kind of driver > > to get entropy from Arm trusted firmware. > > If you intend to make this a generic interface, please clean up the > > references to MediaTek and give it a more generic name. For example > > "Arm Trusted Firmware random number driver". > > > > It will also be helpful if the SMC call number is configurable. > > > > - Lars > > Yes, I'm trying to make this to a generic interface. I'll try to make > HW/platform related dependency to be configurable and let it more > generic. > Thanks for your suggestion. > I don't think it makes sense for each arm64 platform to expose an entropy source via SMC calls in a slightly different way, and model it as a h/w driver. Instead, we should try to standardize this, and perhaps expose it via the architectural helpers that already exist (get_random_seed_long() and friends), so they get plugged into the kernel random pool driver directly. Note that in addition to drivers based on vendor SMC calls, we already have a RNG h/w driver based on OP-TEE as well, where the driver attaches to a standardized trusted OS interface identified by a UUID, and which also gets invoked via SMC calls into secure firmware.