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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 0EFB7C636D4 for ; Thu, 2 Feb 2023 15:56:13 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233116AbjBBP4I (ORCPT ); Thu, 2 Feb 2023 10:56:08 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:57504 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233223AbjBBPzH (ORCPT ); Thu, 2 Feb 2023 10:55:07 -0500 Received: from ams.source.kernel.org (ams.source.kernel.org [IPv6:2604:1380:4601:e00::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 6F67AAD0E; Thu, 2 Feb 2023 07:54:57 -0800 (PST) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ams.source.kernel.org (Postfix) with ESMTPS id D5CE8B826EE; Thu, 2 Feb 2023 15:54:46 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 81EAAC4332A; Thu, 2 Feb 2023 15:54:45 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1675353285; bh=6djvmuAChIFeJKMJvy/scNkMFP3hnJhKKtF5jokukOg=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=r6SUVO4EU/hNfLuDItJpqcKznhgeYxVBZ/K3xDo5aYROrdPEufLEreqp+tJ3cx9KO sj64n7NicEFNeLfV4pvxV8pG/7BBfCZQ78Mw3hHpcPnouII3C3EWZFTvjiwoKpK6kS JHkiwSPykZmX8Qpeadpi5HMoz6i6hiaJbM4lrIug2C0DauZccDlCfjO4I77ZpOMgYl z+kV4YNeNLhx9nhbJMun7gik9M2+hMXXV8lWRwIhAwfuTWR1JCeqM+2GV5qp96qIQP 23+gLx62W6skWuZzxBYD+lmyYybQ3wka9VcCKiWUitb6B6bdYn4WQEKBjr7/zFiQQt 8av9qE2G7ywaA== Received: from johan by xi.lan with local (Exim 4.94.2) (envelope-from ) id 1pNbva-0001mj-Ey; Thu, 02 Feb 2023 16:55:10 +0100 From: Johan Hovold To: Alexandre Belloni , Bjorn Andersson Cc: Andy Gross , Konrad Dybcio , Alessandro Zummo , Rob Herring , Krzysztof Kozlowski , Maximilian Luz , linux-arm-msm@vger.kernel.org, linux-rtc@vger.kernel.org, devicetree@vger.kernel.org, linux-kernel@vger.kernel.org, Johan Hovold Subject: [PATCH v2 22/22] arm64: dts: qcom: sc8280xp-x13s: enable rtc Date: Thu, 2 Feb 2023 16:54:48 +0100 Message-Id: <20230202155448.6715-23-johan+linaro@kernel.org> X-Mailer: git-send-email 2.39.1 In-Reply-To: <20230202155448.6715-1-johan+linaro@kernel.org> References: <20230202155448.6715-1-johan+linaro@kernel.org> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org The Lenovo X13s firmware does not implement the UEFI time runtime services so the RTC in the PM8280K PMIC needs to be accessed directly. To complicate things further, the RTC control and time registers are read-only on this platform so an offset must be stored in some other machine-specific non-volatile memory which an RTC driver can take into account when reading or updating the time. The UEFI firmware (and Windows) use a UEFI variable for this: 882f8c2b-9646-435f-8de5-f208ff80c1bd-RTCInfo but the offset can only be accessed via the Qualcomm UEFI Secure Application residing in the TEE as the firmware does not implement the variable runtime services either. While it is possible to access this UEFI variable from Linux on the X13s, this requires using a fairly complex and reverse-engineered firmware interface. As the only benefit of doing so is to make sure that the UEFI (Windows) and Linux time never gets out of sync, it seems preferable to use the PMIC scratch registers for storing an offset instead. This also avoids flash wear in case of RTC drift, etc. So instead of using the UEFI RTC offset, reserve four bytes in one of the PMIC SDAM scratch-register blocks to hold the RTC offset. Signed-off-by: Johan Hovold --- .../dts/qcom/sc8280xp-lenovo-thinkpad-x13s.dts | 15 +++++++++++++++ 1 file changed, 15 insertions(+) diff --git a/arch/arm64/boot/dts/qcom/sc8280xp-lenovo-thinkpad-x13s.dts b/arch/arm64/boot/dts/qcom/sc8280xp-lenovo-thinkpad-x13s.dts index db406f7774de..6e88e0bb6871 100644 --- a/arch/arm64/boot/dts/qcom/sc8280xp-lenovo-thinkpad-x13s.dts +++ b/arch/arm64/boot/dts/qcom/sc8280xp-lenovo-thinkpad-x13s.dts @@ -683,6 +683,21 @@ &pmk8280_pon_resin { status = "okay"; }; +&pmk8280_rtc { + nvmem-cells = <&rtc_offset>; + nvmem-cell-names = "offset"; + + status = "okay"; +}; + +&pmk8280_sdam_6 { + status = "okay"; + + rtc_offset: rtc-offset@bc { + reg = <0xbc 0x4>; + }; +}; + &pmk8280_vadc { status = "okay"; -- 2.39.1