From patchwork Thu Jun 15 09:27:49 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Valentin Caron X-Patchwork-Id: 13280952 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 bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 89974EB64DB for ; Thu, 15 Jun 2023 09:32:55 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender: Content-Transfer-Encoding:Content-Type:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:MIME-Version:References:In-Reply-To: Message-ID:Date:Subject:CC:To:From:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=3tAWgBTmzIyu9nn9uaGW8YUqSF86NKSno5bHPqZrSAg=; b=C3cIb842jxKZEZ 3TukN6feo9cXS/vvmrPCwyA/4QhbPYdHasTuKBd48HdIDtmjFyMOmOuMMMpTHz++8H+UMTIt0Ndfx Absv4W4C6pFgb7Mivi3y+8COzmocQLj2apBHUtp4Yuw3KQ7Qt8FORVzUgfjdeauQY5so89L/NpxUd x74bObA0flP5Z06JLzJ/7vAfCFhgy3dUIQcrMRB5F2g1mYb+O0oRE6KMPCNisDCCPsAYG4++OGa4d St2xr6ljKNUw+qKQAKo112uP8LFuZTMmS/m2+YtTJHzvIjBiAdyP4vqwMXeWML5rMDfLeidrnwdrH 356EcRi8IyC5d5eKLVsA==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.96 #2 (Red Hat Linux)) id 1q9jLG-00EJ4W-1v; Thu, 15 Jun 2023 09:32:34 +0000 Received: from mx07-00178001.pphosted.com ([185.132.182.106]) by bombadil.infradead.org with esmtps (Exim 4.96 #2 (Red Hat Linux)) id 1q9jL8-00EJ1T-2X for linux-arm-kernel@lists.infradead.org; Thu, 15 Jun 2023 09:32:28 +0000 Received: from pps.filterd (m0288072.ppops.net [127.0.0.1]) by mx07-00178001.pphosted.com (8.17.1.19/8.17.1.19) with ESMTP id 35F8I2F3009956; Thu, 15 Jun 2023 11:32:24 +0200 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=foss.st.com; h=from : to : cc : subject : date : message-id : in-reply-to : references : mime-version : content-transfer-encoding : content-type; s=selector1; bh=Xy/hUYzK/4Hs4UPMJUFskvFcKLM1GyUKIZn77IV+Fes=; b=ykj2xVGd4l8SPjOC+WaEsyn1vfQMeJB19nja7j0WMoq7jGqLyuTksVeSG1ypwhQ7oWbj qdqRfPA/+c69YhcQSIiZss7N5gdsd2LRwaPwCf3S0NsBabQCZB1DW652Ne/wrKke5vPc 0ypd32toBFM/zNCbKNuW+BCS3Rg9WG2DirmEDhKoXq/4hQ2r7/fH//5/YJaDJBDB0nbs Qm7CNUebjRIch7m1yqK6MQVEV6CvmHJrAZtnPzQZLE6sVqkKnd+n11y8fsuJGXR9lZ5G Dqd0JRs+nBQD3fWx4ydRRCxFE1yPK0Uex8nlR/bSzh2cVQGkIeOv+bIKFvVhwZgJVmV8 eA== Received: from beta.dmz-eu.st.com (beta.dmz-eu.st.com [164.129.1.35]) by mx07-00178001.pphosted.com (PPS) with ESMTPS id 3r7s1maxs3-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Thu, 15 Jun 2023 11:32:24 +0200 Received: from euls16034.sgp.st.com (euls16034.sgp.st.com [10.75.44.20]) by beta.dmz-eu.st.com (STMicroelectronics) with ESMTP id 004F810002A; Thu, 15 Jun 2023 11:32:23 +0200 (CEST) Received: from Webmail-eu.st.com (shfdag1node1.st.com [10.75.129.69]) by euls16034.sgp.st.com (STMicroelectronics) with ESMTP id EBF8721A91B; Thu, 15 Jun 2023 11:32:23 +0200 (CEST) Received: from localhost (10.252.8.64) by SHFDAG1NODE1.st.com (10.75.129.69) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2507.21; Thu, 15 Jun 2023 11:32:23 +0200 From: Valentin Caron To: Alessandro Zummo , Alexandre Belloni CC: Alexandre Torgue , Antonio Borneo , Christophe Guibout , Gabriel Fernandez , , , , , Valentin Caron Subject: [PATCH 3/7] rtc: stm32: improve rtc precision Date: Thu, 15 Jun 2023 11:27:49 +0200 Message-ID: <20230615092753.323844-4-valentin.caron@foss.st.com> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20230615092753.323844-1-valentin.caron@foss.st.com> References: <20230615092753.323844-1-valentin.caron@foss.st.com> MIME-Version: 1.0 X-Originating-IP: [10.252.8.64] X-ClientProxiedBy: SHFCAS1NODE2.st.com (10.75.129.73) To SHFDAG1NODE1.st.com (10.75.129.69) X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.205,Aquarius:18.0.957,Hydra:6.0.573,FMLib:17.11.176.26 definitions=2023-06-15_06,2023-06-14_02,2023-05-22_02 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20230615_023227_137636_14942FC3 X-CRM114-Status: GOOD ( 22.76 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org From: Christophe Guibout The rtc is used to update the stgen counter on wake up from low power modes, so it needs to be as much accurate as possible. The maximization of asynchronous divider leads to a 4ms rtc precision clock. By decreasing pred_a to 0, it will have pred_s=32767 (when need_accuracy is true), so stgen clock becomes more accurate with 30us precision. Nevertheless this will leads to an increase of power consumption. Signed-off-by: Christophe Guibout Signed-off-by: Valentin Caron --- drivers/rtc/rtc-stm32.c | 26 ++++++++++++++++++++++---- 1 file changed, 22 insertions(+), 4 deletions(-) diff --git a/drivers/rtc/rtc-stm32.c b/drivers/rtc/rtc-stm32.c index bd7a59a07537..cad88668bcfb 100644 --- a/drivers/rtc/rtc-stm32.c +++ b/drivers/rtc/rtc-stm32.c @@ -114,6 +114,7 @@ struct stm32_rtc_data { void (*clear_events)(struct stm32_rtc *rtc, unsigned int flags); bool has_pclk; bool need_dbp; + bool need_accuracy; }; struct stm32_rtc { @@ -545,6 +546,7 @@ static void stm32_rtc_clear_events(struct stm32_rtc *rtc, static const struct stm32_rtc_data stm32_rtc_data = { .has_pclk = false, .need_dbp = true, + .need_accuracy = false, .regs = { .tr = 0x00, .dr = 0x04, @@ -566,6 +568,7 @@ static const struct stm32_rtc_data stm32_rtc_data = { static const struct stm32_rtc_data stm32h7_rtc_data = { .has_pclk = true, .need_dbp = true, + .need_accuracy = false, .regs = { .tr = 0x00, .dr = 0x04, @@ -596,6 +599,7 @@ static void stm32mp1_rtc_clear_events(struct stm32_rtc *rtc, static const struct stm32_rtc_data stm32mp1_data = { .has_pclk = true, .need_dbp = false, + .need_accuracy = true, .regs = { .tr = 0x00, .dr = 0x04, @@ -636,11 +640,25 @@ static int stm32_rtc_init(struct platform_device *pdev, pred_a_max = STM32_RTC_PRER_PRED_A >> STM32_RTC_PRER_PRED_A_SHIFT; pred_s_max = STM32_RTC_PRER_PRED_S >> STM32_RTC_PRER_PRED_S_SHIFT; - for (pred_a = pred_a_max; pred_a + 1 > 0; pred_a--) { - pred_s = (rate / (pred_a + 1)) - 1; + if (rate > (pred_a_max + 1) * (pred_s_max + 1)) { + dev_err(&pdev->dev, "rtc_ck rate is too high: %dHz\n", rate); + return -EINVAL; + } + + if (rtc->data->need_accuracy) { + for (pred_a = 0; pred_a <= pred_a_max; pred_a++) { + pred_s = (rate / (pred_a + 1)) - 1; - if (((pred_s + 1) * (pred_a + 1)) == rate) - break; + if (pred_s <= pred_s_max && ((pred_s + 1) * (pred_a + 1)) == rate) + break; + } + } else { + for (pred_a = pred_a_max; pred_a + 1 > 0; pred_a--) { + pred_s = (rate / (pred_a + 1)) - 1; + + if (((pred_s + 1) * (pred_a + 1)) == rate) + break; + } } /*