From nobody Tue Sep 16 10:29:38 2025 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 7E72DC4332F for ; Wed, 4 Jan 2023 05:25:34 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230398AbjADFZb (ORCPT ); Wed, 4 Jan 2023 00:25:31 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:55044 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230176AbjADFZZ (ORCPT ); Wed, 4 Jan 2023 00:25:25 -0500 Received: from mail-qt1-x831.google.com (mail-qt1-x831.google.com [IPv6:2607:f8b0:4864:20::831]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 5A69315FE8 for ; Tue, 3 Jan 2023 21:25:24 -0800 (PST) Received: by mail-qt1-x831.google.com with SMTP id j16so26500491qtv.4 for ; Tue, 03 Jan 2023 21:25:24 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=sparkcharge.io; s=google; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:from:to:cc:subject:date :message-id:reply-to; bh=LV9OZ3zFtkDLpf/Q73kAo3k3wQt+efvU2HfxDW5J4xU=; b=Du0R4iD1kfzmb4EfxtgF+gSIOWGDbJD0iExwUv1ZDRundKTzoDa695OqloAYC0BdIX /n4DwNWbqEr7HA4g1IL3tlSoo0NQN+w03uf+axir/nbFf+kNPdFbcIOlOML6znSZsbjY nkIfCEJHC1vW0AGW15gVU9BhfdPv8zwOg2wVOSXX/nPuRQALIAEbs6+oxi9Qf6t34C1t eqhm8vQ30zpztA+A7FQQIAfxEF6XsVS2bhNU++qzYkuqrX8kd6KZzEzmnqdDqOox8ygP XU/RLiMdFYiInbF9Qjk8v6wLb5RdhVb2liw95K3SR3d2ByTcbGODDtamnxo+uiwJCOCX f2NQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:x-gm-message-state:from:to:cc :subject:date:message-id:reply-to; bh=LV9OZ3zFtkDLpf/Q73kAo3k3wQt+efvU2HfxDW5J4xU=; b=Xmfs/8qN6P5zrGXEoQedaUQLcuyUF0jGPLVpyIDxLfS/YrtPB0oyZ3qIz8smDVGC1f eHiZ/k1O+qtbnfqwS9fqedL3N7+RJ2PEQA6X0sXZP2ky/PPQvIEb8XWHKrq1mMQRGuMO 49zhsS5SyPP0dfgqazDLxiEz8HL/STcWAOLIttWHM2Z1oqgcl0AZqDilISnBf3Ami5D3 b06yuGaFk9k4TM/1h8Amjt6TlAjA+aB/tFA60LC1zSZXo1V4BegwaXonxMWpq/yTz5dB pE86i84NnVcAoJR6hVSLDA/msmgHmKNDcML43kdPKl78A0On03E4zZXlupQlLUuwDZiw tGPQ== X-Gm-Message-State: AFqh2kqL1J8z7S6sCaZ/3Q1LSUOZl8m0VOpB6K28Un1Wh2brd1xrVjig 54aIxg9oOc/ObEPN2gzHDDApXA== X-Google-Smtp-Source: AMrXdXsq0aGkcmpSVefm8C3EMlsbGaK7lvGqxzZYrsvn/31+eK+d69jtkytPR+yjgqAzg6dpNX8+Xw== X-Received: by 2002:ac8:47cd:0:b0:3a7:e4ad:5499 with SMTP id d13-20020ac847cd000000b003a7e4ad5499mr70331981qtr.32.1672809923519; Tue, 03 Jan 2023 21:25:23 -0800 (PST) Received: from localhost.localdomain (c-66-31-16-167.hsd1.ma.comcast.net. [66.31.16.167]) by smtp.gmail.com with ESMTPSA id t1-20020ac865c1000000b003a7e4129f83sm19425602qto.85.2023.01.03.21.25.22 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 03 Jan 2023 21:25:23 -0800 (PST) From: Dennis Lambe Jr To: Alessandro Zummo , Alexandre Belloni , Krzysztof Kozlowski , Rob Herring Cc: Atsushi Nemoto , devicetree@vger.kernel.org, linux-kernel@vger.kernel.org, linux-rtc@vger.kernel.org, Dennis Lambe Jr Subject: [PATCH v2 1/3] rtc: m41t80: probe: use IS_ENABLED for CONFIG_OF Date: Wed, 4 Jan 2023 05:25:04 +0000 Message-Id: <20230104052506.575619-2-dennis@sparkcharge.io> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20230104052506.575619-1-dennis@sparkcharge.io> References: <20230104052506.575619-1-dennis@sparkcharge.io> MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" The style guide recommends IS_ENABLED rather than ifdef for wrapping conditional code wherever possible. Functions that are only called on DeviceTree platforms would otherwise need to be cluttered up with __maybe_unused, which is especially undesirable if there's nothing inherently DT-specific about those functions. Signed-off-by: Dennis Lambe Jr --- Notes: v1 -> v2: spelling fix in changelog drivers/rtc/rtc-m41t80.c | 9 +++++---- 1 file changed, 5 insertions(+), 4 deletions(-) diff --git a/drivers/rtc/rtc-m41t80.c b/drivers/rtc/rtc-m41t80.c index 494052dbd39f..f963b76e5fc0 100644 --- a/drivers/rtc/rtc-m41t80.c +++ b/drivers/rtc/rtc-m41t80.c @@ -909,10 +909,11 @@ static int m41t80_probe(struct i2c_client *client) if (IS_ERR(m41t80_data->rtc)) return PTR_ERR(m41t80_data->rtc); =20 -#ifdef CONFIG_OF - wakeup_source =3D of_property_read_bool(client->dev.of_node, - "wakeup-source"); -#endif + if (IS_ENABLED(CONFIG_OF)) { + wakeup_source =3D of_property_read_bool(client->dev.of_node, + "wakeup-source"); + } + if (client->irq > 0) { rc =3D devm_request_threaded_irq(&client->dev, client->irq, NULL, m41t80_handle_irq, --=20 2.25.1 From nobody Tue Sep 16 10:29:38 2025 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 C5B01C4332F for ; Wed, 4 Jan 2023 05:25:44 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230176AbjADFZl (ORCPT ); Wed, 4 Jan 2023 00:25:41 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:55090 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230331AbjADFZ1 (ORCPT ); Wed, 4 Jan 2023 00:25:27 -0500 Received: from mail-qt1-x833.google.com (mail-qt1-x833.google.com [IPv6:2607:f8b0:4864:20::833]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 7FB1E167CA for ; Tue, 3 Jan 2023 21:25:25 -0800 (PST) Received: by mail-qt1-x833.google.com with SMTP id z12so26495868qtv.5 for ; Tue, 03 Jan 2023 21:25:25 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=sparkcharge.io; s=google; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:from:to:cc:subject:date :message-id:reply-to; bh=fFS/lCQcj6VGGmUkQIK4WQwbgzLe7pFGBO2z51//9yI=; b=NKXV9Fm1i9JCRE7A8ERMnQADG9tfJJIjStUM8uI7Zd1ba8vLDANg82dkmoa+A4r7Sl dMKbBcsWYvqtfPI5yAC8Wpfwwaa+El/4iXsUsGEcbwUdURkweWS3Ql8dQHpgDo7x+DFV B7iwmCI9JucvdJDoozwGq3krWcDfKRKAeRnggJW8JRif0eZ3xMQWEH2ty+qTL0iQ1G5u ioHd4/fZ4k+XseTlfWF0qSpOcMhp8zkf0OeXdPgIGhgjIcLws5ECpHVdSyh1LRS1UXau vfAcEakVoDcCZFkwqsaQ+xgpzxaZxeVBhYQcjLqrje261Y7VB5Z2avXB2P6B0u3UQYyK nl4A== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:x-gm-message-state:from:to:cc :subject:date:message-id:reply-to; bh=fFS/lCQcj6VGGmUkQIK4WQwbgzLe7pFGBO2z51//9yI=; b=N5QSxDlVfncnBpwhjyxxPJwUA4zyqsppge4H28I/Ug3Pb7DnVXqJAJx6Hhh/h06vlH V4LAVmePBHFuRIR3bDSiBVH37F5P20GgRXyBsZFIBigpC5cFbS3mmT0TiACInzoV3afM q39GH31EJeO2jgNt/akrWhdQXAO40VoDpf3ktNwkT0wtOXpBSnYFqNkUdSn6tJU8E8/R Zvzhu4LWvS0oKrpQFv1doqfr32pKbNUz0cpYjOikgvsWAhB0MgNZHboq7WxH6xup1B6H Ah8kiKLbIMiIvdxn2wXcEUfEzbcwjSQpx0lKrA84MopGaS04Ag2/d1BKhaMR+yPlkpXz U2GQ== X-Gm-Message-State: AFqh2kqrNKktXjJmdzmreL2jZWOLzKGNM7LicEkM+YKCi+K+xPy+NhH1 5ex3d8bTel8pyeyPkzBq4CQBaQ== X-Google-Smtp-Source: AMrXdXuJA0DQCbJ/n73PHFUtowQN37EANSgPuI19HQ2cdjPM/nUgKiD9pJSVDNum/6Gd4Cd7D0KzxQ== X-Received: by 2002:ac8:44d7:0:b0:3a5:4fa8:141c with SMTP id b23-20020ac844d7000000b003a54fa8141cmr74557522qto.23.1672809924601; Tue, 03 Jan 2023 21:25:24 -0800 (PST) Received: from localhost.localdomain (c-66-31-16-167.hsd1.ma.comcast.net. [66.31.16.167]) by smtp.gmail.com with ESMTPSA id t1-20020ac865c1000000b003a7e4129f83sm19425602qto.85.2023.01.03.21.25.23 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 03 Jan 2023 21:25:24 -0800 (PST) From: Dennis Lambe Jr To: Alessandro Zummo , Alexandre Belloni , Krzysztof Kozlowski , Rob Herring Cc: Atsushi Nemoto , devicetree@vger.kernel.org, linux-kernel@vger.kernel.org, linux-rtc@vger.kernel.org, Dennis Lambe Jr Subject: [PATCH v2 2/3] dt-bindings: m41t80: add xtal load capacitance Date: Wed, 4 Jan 2023 05:25:05 +0000 Message-Id: <20230104052506.575619-3-dennis@sparkcharge.io> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20230104052506.575619-1-dennis@sparkcharge.io> References: <20230104052506.575619-1-dennis@sparkcharge.io> MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" The ST m41t82 and m41t83 support programmable load capacitance from 3.5 pF to 17.4 pF. The hardware defaults to 12.5 pF. The accuracy of the xtal can be calibrated precisely by adjusting the load capacitance. Add default, minimum, and maximum for the standard rtc property quartz-load-femtofarads on compatible devices. Signed-off-by: Dennis Lambe Jr Reviewed-by: Krzysztof Kozlowski --- Notes: v1 -> v2: remove accidental wakeup-sources line suggested by Krzysztof Kozlowski spelling fix in changelog .../devicetree/bindings/rtc/st,m41t80.yaml | 16 ++++++++++++++++ 1 file changed, 16 insertions(+) diff --git a/Documentation/devicetree/bindings/rtc/st,m41t80.yaml b/Documen= tation/devicetree/bindings/rtc/st,m41t80.yaml index fc9c6da6483f..6673adf6e99b 100644 --- a/Documentation/devicetree/bindings/rtc/st,m41t80.yaml +++ b/Documentation/devicetree/bindings/rtc/st,m41t80.yaml @@ -33,6 +33,11 @@ properties: "#clock-cells": const: 1 =20 + quartz-load-femtofarads: + default: 12500 + minimum: 3500 + maximum: 17375 + clock-output-names: maxItems: 1 description: From common clock binding to override the default output = clock name. @@ -46,6 +51,17 @@ properties: =20 allOf: - $ref: rtc.yaml + - if: + not: + properties: + compatible: + contains: + enum: + - st,m41t82 + - st,m41t83 + then: + properties: + quartz-load-femtofarads: false =20 unevaluatedProperties: false =20 --=20 2.25.1 From nobody Tue Sep 16 10:29:38 2025 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 058BDC4332F for ; Wed, 4 Jan 2023 05:25:38 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230455AbjADFZf (ORCPT ); Wed, 4 Jan 2023 00:25:35 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:55086 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230185AbjADFZ1 (ORCPT ); Wed, 4 Jan 2023 00:25:27 -0500 Received: from mail-qt1-x830.google.com (mail-qt1-x830.google.com [IPv6:2607:f8b0:4864:20::830]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 8C8181658A for ; Tue, 3 Jan 2023 21:25:26 -0800 (PST) Received: by mail-qt1-x830.google.com with SMTP id h21so26457994qta.12 for ; Tue, 03 Jan 2023 21:25:26 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=sparkcharge.io; s=google; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:from:to:cc:subject:date :message-id:reply-to; bh=jgeqi6RRPNuIjdr+16qci9xGfe9jHTKnAUBA+hjYEZ0=; b=i+ZpVp3mwT2dg7r2pBy6XLj5KfrohEUpJoq6O8hVqiGvmISCNWCgyBvYhOvbkvaoa+ 5qiXpGkGenGYuxhu2zeoOUvF2PHPgBk707lO27MDyn60VB4ufNR2/P5N7IIrtF5OSGap 4Sagp9ntb2S1Y17WVR/3IQLHGsBthABGCsCD3PGa7MibJHbwmvJ4h4LbMx0OcgAERHom /BAPz3rTSBREIrACwlIYwlAkXTIedssNQFaFtl2TDntb8m3V59YTG4UWu20ISvszMWr0 epwE+RbT4EkeWBJ214kfPPGJPuSnWeoBqE+On0vi+BUkgqMsLJgCLNatvRuxjln+Td1D EhMg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:x-gm-message-state:from:to:cc :subject:date:message-id:reply-to; bh=jgeqi6RRPNuIjdr+16qci9xGfe9jHTKnAUBA+hjYEZ0=; b=R7AXS1zGHabnCoq9WYKTGHDGW8WUgMEFAdik56axYfxSpxZbsdm/7sEBCmKNE89ggK vJQWs4XsJFkbC4CpsoqHhtM8riO1c0LEx5R3b9NJ1tC6Dn0i/kUItCd2NOMyEaRsI15Z PYex/Yt2xY0SR7u4JT4X2XWUUL1F9BANGx8bRAPE69olJUQt0o/yc6Zvfgee+kSEBU6f IcwSVAyXJlpuiTLet99TYXhVp0u1anumrEimYCr1w0QxbEMVfsvmVVv/xn8IFgpnTG+8 pYcj51FrHmsTQVEhlq4hl47LhUE799EwSYqY6L7MTPsdTIERmypGi3qBWQHeLy/qLDqc /JYA== X-Gm-Message-State: AFqh2kqIVs4kqlvK/OsngTlCUefv8HRSGRs+CkcYVDhbjqzI3JWff97N zSQNRzgvF9NUUODFgROLgG+UVA== X-Google-Smtp-Source: AMrXdXsFdnvfK2zYz6sa3lAuau2z4Epb/qTRBrCqn6Ond7JrtcwYz5TNx9+t2yVxdNlvPd2wzL5bmQ== X-Received: by 2002:ac8:6896:0:b0:3ab:6cf1:1e7d with SMTP id m22-20020ac86896000000b003ab6cf11e7dmr63382460qtq.2.1672809925668; Tue, 03 Jan 2023 21:25:25 -0800 (PST) Received: from localhost.localdomain (c-66-31-16-167.hsd1.ma.comcast.net. [66.31.16.167]) by smtp.gmail.com with ESMTPSA id t1-20020ac865c1000000b003a7e4129f83sm19425602qto.85.2023.01.03.21.25.24 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 03 Jan 2023 21:25:25 -0800 (PST) From: Dennis Lambe Jr To: Alessandro Zummo , Alexandre Belloni , Krzysztof Kozlowski , Rob Herring Cc: Atsushi Nemoto , devicetree@vger.kernel.org, linux-kernel@vger.kernel.org, linux-rtc@vger.kernel.org, Dennis Lambe Jr Subject: [PATCH v2 3/3] rtc: m41t80: set xtal load capacitance from DT Date: Wed, 4 Jan 2023 05:25:06 +0000 Message-Id: <20230104052506.575619-4-dennis@sparkcharge.io> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20230104052506.575619-1-dennis@sparkcharge.io> References: <20230104052506.575619-1-dennis@sparkcharge.io> MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" Add support for specifying the xtal load capacitance in the DT node for devices with an Analog Calibration register. the m41t82 and m41t83 support xtal load capacitance from 3.5 pF to 17.4 pF. If no xtal load capacitance is specified, the battery-backed register won't be modified. The hardware defaults to 12.5 pF on reset. Signed-off-by: Dennis Lambe Jr --- drivers/rtc/rtc-m41t80.c | 75 +++++++++++++++++++++++++++++++++++++--- 1 file changed, 71 insertions(+), 4 deletions(-) diff --git a/drivers/rtc/rtc-m41t80.c b/drivers/rtc/rtc-m41t80.c index f963b76e5fc0..85bde7130a4d 100644 --- a/drivers/rtc/rtc-m41t80.c +++ b/drivers/rtc/rtc-m41t80.c @@ -44,12 +44,17 @@ #define M41T80_REG_ALARM_MIN 0x0d #define M41T80_REG_ALARM_SEC 0x0e #define M41T80_REG_FLAGS 0x0f +#define M41T80_REG_AC 0x12 #define M41T80_REG_SQW 0x13 =20 #define M41T80_DATETIME_REG_SIZE (M41T80_REG_YEAR + 1) #define M41T80_ALARM_REG_SIZE \ (M41T80_REG_ALARM_SEC + 1 - M41T80_REG_ALARM_MON) =20 +#define M41T80_AC_MIN 3500 +#define M41T80_AC_MAX 17375 +#define M41T80_AC_DEFAULT 12500 + #define M41T80_SQW_MAX_FREQ 32768 =20 #define M41T80_SEC_ST BIT(7) /* ST: Stop Bit */ @@ -68,6 +73,7 @@ #define M41T80_FEATURE_SQ BIT(2) /* Squarewave feature */ #define M41T80_FEATURE_WD BIT(3) /* Extra watchdog resolution */ #define M41T80_FEATURE_SQ_ALT BIT(4) /* RSx bits are in reg 4 */ +#define M41T80_FEATURE_AC BIT(5) /* Analog calibration */ =20 static const struct i2c_device_id m41t80_id[] =3D { { "m41t62", M41T80_FEATURE_SQ | M41T80_FEATURE_SQ_ALT }, @@ -75,8 +81,10 @@ static const struct i2c_device_id m41t80_id[] =3D { { "m41t80", M41T80_FEATURE_SQ }, { "m41t81", M41T80_FEATURE_HT | M41T80_FEATURE_SQ}, { "m41t81s", M41T80_FEATURE_HT | M41T80_FEATURE_BL | M41T80_FEATURE_SQ }, - { "m41t82", M41T80_FEATURE_HT | M41T80_FEATURE_BL | M41T80_FEATURE_SQ }, - { "m41t83", M41T80_FEATURE_HT | M41T80_FEATURE_BL | M41T80_FEATURE_SQ }, + { "m41t82", M41T80_FEATURE_HT | M41T80_FEATURE_BL | M41T80_FEATURE_SQ + | M41T80_FEATURE_AC }, + { "m41t83", M41T80_FEATURE_HT | M41T80_FEATURE_BL | M41T80_FEATURE_SQ + | M41T80_FEATURE_AC }, { "m41st84", M41T80_FEATURE_HT | M41T80_FEATURE_BL | M41T80_FEATURE_SQ }, { "m41st85", M41T80_FEATURE_HT | M41T80_FEATURE_BL | M41T80_FEATURE_SQ }, { "m41st87", M41T80_FEATURE_HT | M41T80_FEATURE_BL | M41T80_FEATURE_SQ }, @@ -108,11 +116,13 @@ static const __maybe_unused struct of_device_id m41t8= 0_of_match[] =3D { }, { .compatible =3D "st,m41t82", - .data =3D (void *)(M41T80_FEATURE_HT | M41T80_FEATURE_BL | M41T80_FEATUR= E_SQ) + .data =3D (void *)(M41T80_FEATURE_HT | M41T80_FEATURE_BL | M41T80_FEATUR= E_SQ + | M41T80_FEATURE_AC) }, { .compatible =3D "st,m41t83", - .data =3D (void *)(M41T80_FEATURE_HT | M41T80_FEATURE_BL | M41T80_FEATUR= E_SQ) + .data =3D (void *)(M41T80_FEATURE_HT | M41T80_FEATURE_BL | M41T80_FEATUR= E_SQ + | M41T80_FEATURE_AC) }, { .compatible =3D "st,m41t84", @@ -405,6 +415,54 @@ static const struct rtc_class_ops m41t80_rtc_ops =3D { .alarm_irq_enable =3D m41t80_alarm_irq_enable, }; =20 +static u8 to_sign_magnitude_u8(int n) +{ + if (n < 0) + return 0x80 | -n; + return n; +} + +static int m41t80_encode_ac(int quartz_load) +{ + if (quartz_load < M41T80_AC_MIN || quartz_load > M41T80_AC_MAX) + return -EINVAL; + + /* + * register representation is the per-capacitor offset from its default + * value in units of 1/4 pF, in sign-magnitude form. + */ + return to_sign_magnitude_u8((quartz_load - M41T80_AC_DEFAULT) / 125); +} + +static int m41t80_set_ac(struct m41t80_data *m41t80_data, int quartz_load) +{ + struct i2c_client *client =3D m41t80_data->client; + struct device *dev =3D &client->dev; + int ret; + int ac; + + if (!(m41t80_data->features & M41T80_FEATURE_AC)) { + dev_err(dev, "analog calibration requested but not supported\n"); + return -EOPNOTSUPP; + } + + ac =3D m41t80_encode_ac(quartz_load); + if (ac < 0) { + dev_err(dev, "quartz load %d fF out of range\n", + quartz_load); + return ac; + } + + ret =3D i2c_smbus_write_byte_data(client, M41T80_REG_AC, ac); + if (ret < 0) { + dev_err(dev, "Can't set AC register\n"); + return ret; + } + + dev_info(dev, "quartz load set to %d fF (AC=3D0x%x)\n", quartz_load, ac); + return 0; +} + #ifdef CONFIG_PM_SLEEP static int m41t80_suspend(struct device *dev) { @@ -883,6 +941,7 @@ static int m41t80_probe(struct i2c_client *client) struct rtc_time tm; struct m41t80_data *m41t80_data =3D NULL; bool wakeup_source =3D false; + u32 quartz_load =3D M41T80_AC_DEFAULT; =20 if (!i2c_check_functionality(client->adapter, I2C_FUNC_SMBUS_I2C_BLOCK | I2C_FUNC_SMBUS_BYTE_DATA)) { @@ -912,6 +971,14 @@ static int m41t80_probe(struct i2c_client *client) if (IS_ENABLED(CONFIG_OF)) { wakeup_source =3D of_property_read_bool(client->dev.of_node, "wakeup-source"); + + rc =3D of_property_read_u32(client->dev.of_node, + "quartz-load-femtofarads", + &quartz_load); + if (!rc) + m41t80_set_ac(m41t80_data, quartz_load); + else if (rc !=3D -EINVAL) + dev_err(&client->dev, "quartz-load-femtofarads property value is missin= g or invalid\n"); } =20 if (client->irq > 0) { --=20 2.25.1