From patchwork Thu May 12 14:39:19 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Miquel Raynal X-Patchwork-Id: 1630223 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@bilbo.ozlabs.org Authentication-Results: bilbo.ozlabs.org; dkim=pass (2048-bit key; unprotected) header.d=bootlin.com header.i=@bootlin.com header.a=rsa-sha256 header.s=gm1 header.b=cq+OwGFw; dkim-atps=neutral Authentication-Results: ozlabs.org; spf=pass (sender SPF authorized) smtp.mailfrom=vger.kernel.org (client-ip=2620:137:e000::1:20; helo=out1.vger.email; envelope-from=linux-rtc-owner@vger.kernel.org; receiver=) Received: from out1.vger.email (out1.vger.email [IPv6:2620:137:e000::1:20]) by bilbo.ozlabs.org (Postfix) with ESMTP id 4KzZDZ6h3Zz9sGF for ; Fri, 13 May 2022 00:39:42 +1000 (AEST) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1355464AbiELOjl (ORCPT ); Thu, 12 May 2022 10:39:41 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:47580 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1355479AbiELOjj (ORCPT ); Thu, 12 May 2022 10:39:39 -0400 Received: from relay12.mail.gandi.net (relay12.mail.gandi.net [217.70.178.232]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id A19B82609F8; Thu, 12 May 2022 07:39:34 -0700 (PDT) Received: (Authenticated sender: miquel.raynal@bootlin.com) by mail.gandi.net (Postfix) with ESMTPSA id ED338200003; Thu, 12 May 2022 14:39:31 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=bootlin.com; s=gm1; t=1652366373; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=eygjNo54yH7YFbhwS7JqFlsyEkKXUEKaiZx0s7QYlck=; b=cq+OwGFw6cyqrvX22fB6085xkzK9zbzjvfBiqFWPEceqKiCqDOhmEKzD2lrMROjw/Tqpi9 SH2d9LDH8r0S+LhgQ2wIctkfW370k1oc7njcxeA01RaEfJT78ObnLdMsvcudo2E7a6Ht6k B3z1XTxCy+gvtv7vwE7fC8K/t3CrLj7ELE1SERYzihG+XUBHDx1LHG0uGKyqw/VhlsPk96 ZOIyqYbPwlGkgYiT2Bveoh+XDV1AF9XmzIXgltQ4YF9O3jFDTTiBGylc/R5Lzxsb1n96CO EG7lE2WofvuOgS/ZR02OCgG28NSFShfMYM8I0zdVmepAYwKc47ILPnDQuc+4hQ== From: Miquel Raynal To: Alessandro Zummo , Alexandre Belloni , Rob Herring , Krzysztof Kozlowski , Geert Uytterhoeven , Magnus Damm Cc: Miquel Raynal , linux-rtc@vger.kernel.org, linux-renesas-soc@vger.kernel.org, devicetree@vger.kernel.org, Gareth Williams , Milan Stevanovic , Jimmy Lalande , Pascal Eberhard , Thomas Petazzoni , Herve Codina , Clement Leger Subject: [PATCH v5 4/5] rtc: rzn1: Add oscillator offset support Date: Thu, 12 May 2022 16:39:19 +0200 Message-Id: <20220512143920.238987-5-miquel.raynal@bootlin.com> X-Mailer: git-send-email 2.27.0 In-Reply-To: <20220512143920.238987-1-miquel.raynal@bootlin.com> References: <20220512143920.238987-1-miquel.raynal@bootlin.com> MIME-Version: 1.0 X-Spam-Status: No, score=-2.8 required=5.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF,RCVD_IN_DNSWL_LOW,SPF_HELO_NONE, SPF_PASS,T_SCC_BODY_TEXT_LINE autolearn=ham autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on lindbergh.monkeyblade.net Precedence: bulk List-ID: X-Mailing-List: linux-rtc@vger.kernel.org The RZN1 RTC can compensate the imprecision of the oscillator up to approximately 190ppm. Seconds can last slightly shorter or longer depending on the configuration. Below ~65ppm of correction, we can change the time spent in a second every minute, which is the most accurate compensation that the RTC can offer. Above, the compensation will be active every 20s. Signed-off-by: Miquel Raynal Reported-by: kernel test robot --- drivers/rtc/rtc-rzn1.c | 73 ++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 73 insertions(+) diff --git a/drivers/rtc/rtc-rzn1.c b/drivers/rtc/rtc-rzn1.c index 7ee190daa651..79b72488231c 100644 --- a/drivers/rtc/rtc-rzn1.c +++ b/drivers/rtc/rtc-rzn1.c @@ -247,12 +247,85 @@ static int rzn1_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *alrm) return 0; } +static int rzn1_rtc_read_offset(struct device *dev, long *offset) +{ + struct rzn1_rtc *rtc = dev_get_drvdata(dev); + unsigned int ppb_per_step; + bool subtract; + u32 val; + + val = readl(rtc->base + RZN1_RTC_SUBU); + ppb_per_step = val & RZN1_RTC_SUBU_DEV ? 1017 : 3051; + subtract = val & RZN1_RTC_SUBU_DECR; + val &= 0x3F; + + if (!val) + *offset = 0; + else if (subtract) + *offset = -(((~val) & 0x3F) + 1) * ppb_per_step; + else + *offset = (val - 1) * ppb_per_step; + + return 0; +} + +static int rzn1_rtc_set_offset(struct device *dev, long offset) +{ + struct rzn1_rtc *rtc = dev_get_drvdata(dev); + unsigned int steps, ppb_per_step; + int stepsh, stepsl; + u32 val; + int ret; + + /* + * Check which resolution mode (every 20 or 60s) can be used. + * Between 2 and 124 clock pulses can be added or substracted. + * + * In 20s mode, the minimum resolution is 2 / (32768 * 20) which is + * close to 3051 ppb. In 60s mode, the resolution is closer to 1017. + */ + stepsh = DIV_ROUND_CLOSEST(offset, 1017); + stepsl = DIV_ROUND_CLOSEST(offset, 3051); + + if (stepsh >= -0x3E && stepsh <= 0x3E) { + ppb_per_step = 1017; + steps = stepsh; + val |= RZN1_RTC_SUBU_DEV; + } else if (stepsl >= -0x3E && stepsl <= 0x3E) { + ppb_per_step = 3051; + steps = stepsl; + } else { + return -ERANGE; + } + + if (!steps) + return 0; + + if (steps > 0) { + val |= steps + 1; + } else { + val |= RZN1_RTC_SUBU_DECR; + val |= (~(-steps - 1)) & 0x3F; + } + + ret = readl_poll_timeout(rtc->base + RZN1_RTC_CTL2, val, + !(val & RZN1_RTC_CTL2_WUST), 100, 2000000); + if (ret) + return ret; + + writel(val, rtc->base + RZN1_RTC_SUBU); + + return 0; +} + static const struct rtc_class_ops rzn1_rtc_ops = { .read_time = rzn1_rtc_read_time, .set_time = rzn1_rtc_set_time, .read_alarm = rzn1_rtc_read_alarm, .set_alarm = rzn1_rtc_set_alarm, .alarm_irq_enable = rzn1_rtc_alarm_irq_enable, + .read_offset = rzn1_rtc_read_offset, + .set_offset = rzn1_rtc_set_offset, }; static int rzn1_rtc_probe(struct platform_device *pdev)