From patchwork Fri Oct 28 22:55:19 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Paul Cercueil X-Patchwork-Id: 13024383 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 79FE1FA3743 for ; Fri, 28 Oct 2022 22:56:29 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230194AbiJ1W42 (ORCPT ); Fri, 28 Oct 2022 18:56:28 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:43762 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230197AbiJ1W4I (ORCPT ); Fri, 28 Oct 2022 18:56:08 -0400 Received: from aposti.net (aposti.net [89.234.176.197]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 4E8C91F5246; Fri, 28 Oct 2022 15:56:06 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=crapouillou.net; s=mail; t=1666997730; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=RvJj+3xY9RbhTi17+j1hh7xVviAFKRxXo4nyj02tbpM=; b=HZOqXXpfdzNX6zPLA4Js1X6WpuSNU4ALdzg43R66pCt/RenTadFhbMEsdRZcYygTQ1AL3u 0c6IvJqM2oPiJc5hzZih4B90wWxQWosKbEqk8yofZDHTU8xO/sG2nzBbQcgfYoWqxfSNyA BvuGgGA12b2iW26xvKZqhPdbMe5qoEw= From: Paul Cercueil To: Alessandro Zummo , Alexandre Belloni , Rob Herring , Krzysztof Kozlowski Cc: linux-rtc@vger.kernel.org, devicetree@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mips@vger.kernel.org, od@opendingux.net, Paul Cercueil Subject: [PATCH v2 4/4] rtc: jz4740: Support for fine-tuning the RTC clock Date: Fri, 28 Oct 2022 23:55:19 +0100 Message-Id: <20221028225519.89210-5-paul@crapouillou.net> In-Reply-To: <20221028225519.89210-1-paul@crapouillou.net> References: <20221028225519.89210-1-paul@crapouillou.net> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-mips@vger.kernel.org Write the NC1HZ and ADJC register fields, which allow to tweak the frequency of the RTC clock, so that it can run as accurately as possible. Signed-off-by: Paul Cercueil --- drivers/rtc/rtc-jz4740.c | 45 ++++++++++++++++++++++++++++++++++++++++ 1 file changed, 45 insertions(+) diff --git a/drivers/rtc/rtc-jz4740.c b/drivers/rtc/rtc-jz4740.c index 1602e8a4283a..70b63ce75e21 100644 --- a/drivers/rtc/rtc-jz4740.c +++ b/drivers/rtc/rtc-jz4740.c @@ -5,6 +5,7 @@ * JZ4740 SoC RTC driver */ +#include #include #include #include @@ -41,6 +42,9 @@ #define JZ_RTC_CTRL_AE BIT(2) #define JZ_RTC_CTRL_ENABLE BIT(0) +#define JZ_RTC_REGULATOR_NC1HZ_MASK GENMASK(15, 0) +#define JZ_RTC_REGULATOR_ADJC_MASK GENMASK(25, 16) + /* Magic value to enable writes on jz4780 */ #define JZ_RTC_WENR_MAGIC 0xA55A @@ -61,6 +65,7 @@ struct jz4740_rtc { enum jz4740_rtc_type type; struct rtc_device *rtc; + struct clk *clk; struct clk_hw clk32k; @@ -217,12 +222,51 @@ static int jz4740_rtc_alarm_irq_enable(struct device *dev, unsigned int enable) return jz4740_rtc_ctrl_set_bits(rtc, JZ_RTC_CTRL_AF_IRQ, enable); } +static int jz4740_rtc_read_offset(struct device *dev, long *offset) +{ + struct jz4740_rtc *rtc = dev_get_drvdata(dev); + long rate = clk_get_rate(rtc->clk); + s32 nc1hz, adjc, offset1k; + u32 reg; + + reg = jz4740_rtc_reg_read(rtc, JZ_REG_RTC_REGULATOR); + nc1hz = FIELD_GET(JZ_RTC_REGULATOR_NC1HZ_MASK, reg); + adjc = FIELD_GET(JZ_RTC_REGULATOR_ADJC_MASK, reg); + + offset1k = (nc1hz - rate + 1) * 1024L + adjc; + *offset = offset1k * 1000000L / (rate * 1024L); + + return 0; +} + +static int jz4740_rtc_set_offset(struct device *dev, long offset) +{ + struct jz4740_rtc *rtc = dev_get_drvdata(dev); + long rate = clk_get_rate(rtc->clk); + s32 offset1k, adjc, nc1hz; + + offset1k = div_s64_rem(offset * rate * 1024LL, 1000000LL, &adjc); + nc1hz = rate - 1 + offset1k / 1024L; + + if (adjc < 0) { + nc1hz--; + adjc += 1024; + } + + nc1hz = FIELD_PREP(JZ_RTC_REGULATOR_NC1HZ_MASK, nc1hz); + adjc = FIELD_PREP(JZ_RTC_REGULATOR_ADJC_MASK, adjc); + + return jz4740_rtc_reg_write(rtc, JZ_REG_RTC_REGULATOR, nc1hz | adjc); +} + static const struct rtc_class_ops jz4740_rtc_ops = { .read_time = jz4740_rtc_read_time, .set_time = jz4740_rtc_set_time, .read_alarm = jz4740_rtc_read_alarm, .set_alarm = jz4740_rtc_set_alarm, .alarm_irq_enable = jz4740_rtc_alarm_irq_enable, + .read_offset = jz4740_rtc_read_offset, + .set_offset = jz4740_rtc_set_offset, }; static irqreturn_t jz4740_rtc_irq(int irq, void *data) @@ -353,6 +397,7 @@ static int jz4740_rtc_probe(struct platform_device *pdev) spin_lock_init(&rtc->lock); + rtc->clk = clk; platform_set_drvdata(pdev, rtc); device_init_wakeup(dev, 1);