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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 20984C54E94 for ; Thu, 26 Jan 2023 14:23:37 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232086AbjAZOXf (ORCPT ); Thu, 26 Jan 2023 09:23:35 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:56326 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231939AbjAZOXD (ORCPT ); Thu, 26 Jan 2023 09:23:03 -0500 Received: from dfw.source.kernel.org (dfw.source.kernel.org [139.178.84.217]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 5DAFD241ED; Thu, 26 Jan 2023 06:23:02 -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 dfw.source.kernel.org (Postfix) with ESMTPS id 2055C61843; Thu, 26 Jan 2023 14:23:02 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 82F47C433A1; Thu, 26 Jan 2023 14:23:01 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1674742981; bh=5UwR9QbyWi/Z/2mgCV5ah8EZM6pifSRECiAKO2qRn28=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=uoAiN7RLIltAF2itdi3Ajs7/6S33o92wkpcy+qExHZNJo+NeZy1wAm5c8lDdbmCj/ Y7/do4gY6riMzI6mBqMH8aJB+0YJkh41cyZeWwHMSOPcx8UKe+94GDN8lYf8ivezIT r2LjK+N8Vwj3ko5OVXCN3gXzffaET5/HLEFbqJ6osHexUbhLeDIx9xSYQX5x2AwGb9 GOrRVhWZQIQDcuWCr2FbND7cUkG7AWElZKRBsY+ipbZqu94DFtwIpMLi7d3RQrlqhS J05jHWiqLRMKeyPv8PmleXqtaweyzMgdm3b7hMTlHIAig502LNjiSBg4d5JZYGR8U8 tbGdCvx76bkow== Received: from johan by xi.lan with local (Exim 4.94.2) (envelope-from ) id 1pL39e-0006jI-2J; Thu, 26 Jan 2023 15:23:06 +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 24/24] arm64: dts: qcom: sc8280xp-x13s: enable rtc Date: Thu, 26 Jan 2023 15:20:57 +0100 Message-Id: <20230126142057.25715-25-johan+linaro@kernel.org> X-Mailer: git-send-email 2.39.1 In-Reply-To: <20230126142057.25715-1-johan+linaro@kernel.org> References: <20230126142057.25715-1-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 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