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=-2.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 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 3CFD3C43603 for ; Thu, 12 Dec 2019 14:44:05 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 1E04A21655 for ; Thu, 12 Dec 2019 14:44:05 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729788AbfLLOoE (ORCPT ); Thu, 12 Dec 2019 09:44:04 -0500 Received: from foss.arm.com ([217.140.110.172]:49196 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729526AbfLLOoE (ORCPT ); Thu, 12 Dec 2019 09:44:04 -0500 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 4B0E530E; Thu, 12 Dec 2019 06:44:03 -0800 (PST) Received: from bogus (e107155-lin.cambridge.arm.com [10.1.196.42]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id D90EA3F718; Thu, 12 Dec 2019 06:44:00 -0800 (PST) Date: Thu, 12 Dec 2019 14:43:55 +0000 From: Sudeep Holla To: Ard Biesheuvel Cc: Neal Liu , Catalin Marinas , Will Deacon , Marc Zyngier , Lars Persson , Mark Rutland , DTML , Herbert Xu , wsd_upstream , Sean Wang , Linux Kernel Mailing List , Rob Herring , Crystal Guo =?utf-8?B?KOmDreaZtik=?= , "linux-crypto@vger.kernel.org" , Matt Mackall , Matthias Brugger , Sudeep Holla , "linux-mediatek@lists.infradead.org" , "linux-arm-kernel@lists.infradead.org" Subject: Re: [PATCH v5 3/3] hwrng: add mtk-sec-rng driver Message-ID: <20191212144355.GA13263@bogus> 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> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.9.4 (2018-02-28) Sender: devicetree-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: devicetree@vger.kernel.org On Mon, Dec 02, 2019 at 04:12:09PM +0000, Ard Biesheuvel wrote: > (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. Yes, I agree. I had raised the issue internally and forgot to follow up. I raised this few months back after I read a blog[1] -- Regards, Sudeep [1] https://community.arm.com/developer/ip-products/processors/f/cortex-a-forum/43679/arm-really-should-standardize-an-smc-interface-for-hardware-random-number-generators