From patchwork Mon Apr 18 18:49:33 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Paul Cercueil X-Patchwork-Id: 563152 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 44B94C433FE for ; Mon, 18 Apr 2022 18:51:47 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S235921AbiDRSyY (ORCPT ); Mon, 18 Apr 2022 14:54:24 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:40420 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1347541AbiDRSxV (ORCPT ); Mon, 18 Apr 2022 14:53:21 -0400 Received: from aposti.net (aposti.net [89.234.176.197]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id EF6502409F; Mon, 18 Apr 2022 11:50:36 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=crapouillou.net; s=mail; t=1650307798; 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=c/CT07nqqL/kRUfaHG3whhK5ysTGqgD0sA53BitiVSo=; b=P/2SAq3V8XLIIw3N33ms4X7AHzfiKEDhTzzLbmZEhHIdJ5TuaQtBKB5nHUqwJ4DzEbNcuJ HPKn1kEAJ7i0umFwILtCLvi7LEi1dQfpguqWX680yq5mBPy11xljkr8+zlonLjRze+5l42 mPQIc9Sh3Q5jiz7f4MM+HBUI9MHgWUU= From: Paul Cercueil To: Alessandro Zummo , Alexandre Belloni Cc: list@opendingux.net, linux-rtc@vger.kernel.org, devicetree@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mips@vger.kernel.org, Paul Cercueil Subject: [PATCH 5/5] rtc: jz4740: Support for fine-tuning the RTC clock Date: Mon, 18 Apr 2022 19:49:33 +0100 Message-Id: <20220418184933.13172-6-paul@crapouillou.net> In-Reply-To: <20220418184933.13172-1-paul@crapouillou.net> References: <20220418184933.13172-1-paul@crapouillou.net> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: devicetree@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 f4c9b6058f07..f275e58a9cea 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 @@ -64,6 +68,7 @@ struct jz4740_rtc { enum jz4740_rtc_type type; struct rtc_device *rtc; + struct clk *clk; struct clk_hw clk32k; @@ -222,12 +227,51 @@ 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) @@ -378,6 +422,7 @@ 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);