From patchwork Wed Nov 6 19:46:25 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Steve Muckle X-Patchwork-Id: 1190663 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@bilbo.ozlabs.org Authentication-Results: ozlabs.org; spf=none (no SPF record) smtp.mailfrom=vger.kernel.org (client-ip=209.132.180.67; helo=vger.kernel.org; envelope-from=linux-rtc-owner@vger.kernel.org; receiver=) Authentication-Results: ozlabs.org; dmarc=pass (p=reject dis=none) header.from=google.com Authentication-Results: ozlabs.org; dkim=pass (2048-bit key; unprotected) header.d=google.com header.i=@google.com header.b="bMol0jV6"; dkim-atps=neutral Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by ozlabs.org (Postfix) with ESMTP id 477cVZ114xz9sP4 for ; Thu, 7 Nov 2019 06:46:46 +1100 (AEDT) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727319AbfKFTqp (ORCPT ); Wed, 6 Nov 2019 14:46:45 -0500 Received: from mail-pf1-f201.google.com ([209.85.210.201]:50648 "EHLO mail-pf1-f201.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726713AbfKFTqn (ORCPT ); Wed, 6 Nov 2019 14:46:43 -0500 Received: by mail-pf1-f201.google.com with SMTP id e13so13148118pff.17 for ; Wed, 06 Nov 2019 11:46:41 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20161025; h=date:message-id:mime-version:subject:from:to:cc; bh=XMIoZmq3jzflCx/mOOBG8L+JHVjKdPs5Ze6dku/isc8=; b=bMol0jV6gQMh4E3B2H837bFujfxShKd7aFYex3oQh76AgZHWxQAJxDcki+arj1XaMw zetFAVUTVnvecFKwY/bgQFYe4cUPxHrYu24rdycUO0yj1FKnz3QMTKlLoNMq2eScr1a8 OQSRIPY+UiH509bu20sMuySS8jRDCXTV54fQNGPaoZ/YhnfFEY1zSrfjLMLe2dxIu71C 9LawlybmZsw4CEFKGzTFHPMUYKEg0gXzNSK6IXV9JmGL/uat3VsL2ybIduQZx3HP1RNH Lc71aKXI0TG0SNFTR8shGe5xf3PSIyZanQjwOGyE8OLjLNCHaezVnfJARiXRPkBsv/YS 6hQg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:message-id:mime-version:subject:from:to:cc; bh=XMIoZmq3jzflCx/mOOBG8L+JHVjKdPs5Ze6dku/isc8=; b=YYoLsqESl2itBAQbpfG5QLNq6BoKbMk9fKizsDnpo5/Sl3jSdJxpfa89k63n972e5S U5/N111GYYG3K9dVjUNZL/chi+hRqzbCqVbBK0q+bCf/dNlxCOuiO2HpC2j6SQDBsepx DnAyt+Eahgayp8aVvBm948mvxFYBivuWIq868vXCnxclddaF121odcppN6nhiZf7AeSc V4LYz3lm3lyM1chliUB7kGjKYRZrZF9iKTVHSsadbDaIa6vMXesgQLq2zRjfOMUBYHMe iOsEiOV/tQYUWeRkAKBl2eB6/YHAclyoG617gJ0wZ6OAUUh9dDKDie2cdeZYurEhK56K UMqw== X-Gm-Message-State: APjAAAXo/zHf9pe3FzK/QQ2oX0mSF3jQHMsjdGwpt4dMrDNj03Y+ZqKS ldJzR4wXMG4sLL1Ya3WSGTGRjif7CHcA X-Google-Smtp-Source: APXvYqwt4qM5R0zDv+lGCi4SZzw6mIxaprwzDEWcuzztj6HRSd5IOz1TMwpaUdYlD5mkkc7cZfXJTWmyTUOd X-Received: by 2002:a63:a05c:: with SMTP id u28mr5138858pgn.333.1573069600951; Wed, 06 Nov 2019 11:46:40 -0800 (PST) Date: Wed, 6 Nov 2019 11:46:25 -0800 Message-Id: <20191106194625.116692-1-smuckle@google.com> Mime-Version: 1.0 X-Mailer: git-send-email 2.24.0.rc1.363.gb1bccd3e3d-goog Subject: [PATCH] rtc: class: support hctosys from modular RTC drivers From: Steve Muckle To: Alessandro Zummo , Alexandre Belloni Cc: linux-kernel@vger.kernel.org, linux-rtc@vger.kernel.org, kernel-team@android.com, Steve Muckle Sender: linux-rtc-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-rtc@vger.kernel.org Due to distribution constraints it may not be possible to statically compile the required RTC driver into the kernel. Expand RTC_HCTOSYS support to cover all RTC devices (statically compiled or not) by checking at the end of RTC device registration whether the time should be synced. Signed-off-by: Steve Muckle --- drivers/rtc/Kconfig | 18 ++++++----- drivers/rtc/Makefile | 1 - drivers/rtc/class.c | 63 +++++++++++++++++++++++++++++++++++++++ drivers/rtc/hctosys.c | 69 ------------------------------------------- 4 files changed, 73 insertions(+), 78 deletions(-) delete mode 100644 drivers/rtc/hctosys.c diff --git a/drivers/rtc/Kconfig b/drivers/rtc/Kconfig index 1adf9f815652..f663d77deb41 100644 --- a/drivers/rtc/Kconfig +++ b/drivers/rtc/Kconfig @@ -35,14 +35,16 @@ config RTC_HCTOSYS_DEVICE depends on RTC_HCTOSYS default "rtc0" help - The RTC device that will be used to (re)initialize the system - clock, usually rtc0. Initialization is done when the system - starts up, and when it resumes from a low power state. This - device should record time in UTC, since the kernel won't do - timezone correction. - - The driver for this RTC device must be loaded before late_initcall - functions run, so it must usually be statically linked. + The RTC device that will be used to (re)initialize the system clock, + usually rtc0. Initialization is done when the driver for the RTC + device registers, and when it resumes from a low power state. This + device should record time in UTC, since the kernel won't do timezone + correction. + + During startup it is useful to initialize the system clock from the + RTC as early as possible. For this reason the driver for this RTC + device should be statically linked, or alternately, the kernel module + for the RTC device driver loaded immediately. This clock should be battery-backed, so that it reads the correct time when the system boots from a power-off state. Otherwise, your diff --git a/drivers/rtc/Makefile b/drivers/rtc/Makefile index 4ac8f19fb631..33f932d08262 100644 --- a/drivers/rtc/Makefile +++ b/drivers/rtc/Makefile @@ -6,7 +6,6 @@ ccflags-$(CONFIG_RTC_DEBUG) := -DDEBUG obj-$(CONFIG_RTC_LIB) += lib.o -obj-$(CONFIG_RTC_HCTOSYS) += hctosys.o obj-$(CONFIG_RTC_SYSTOHC) += systohc.o obj-$(CONFIG_RTC_CLASS) += rtc-core.o obj-$(CONFIG_RTC_MC146818_LIB) += rtc-mc146818-lib.o diff --git a/drivers/rtc/class.c b/drivers/rtc/class.c index 9458e6d6686a..b1ed5f3be223 100644 --- a/drivers/rtc/class.c +++ b/drivers/rtc/class.c @@ -34,6 +34,64 @@ static void rtc_device_release(struct device *dev) #ifdef CONFIG_RTC_HCTOSYS_DEVICE /* Result of the last RTC to system clock attempt. */ int rtc_hctosys_ret = -ENODEV; + +/* IMPORTANT: the RTC only stores whole seconds. It is arbitrary + * whether it stores the most close value or the value with partial + * seconds truncated. However, it is important that we use it to store + * the truncated value. This is because otherwise it is necessary, + * in an rtc sync function, to read both xtime.tv_sec and + * xtime.tv_nsec. On some processors (i.e. ARM), an atomic read + * of >32bits is not possible. So storing the most close value would + * slow down the sync API. So here we have the truncated value and + * the best guess is to add 0.5s. + */ + +static int rtc_hctosys(void) +{ + int err = -ENODEV; + struct rtc_time tm; + struct timespec64 tv64 = { + .tv_nsec = NSEC_PER_SEC >> 1, + }; + struct rtc_device *rtc = rtc_class_open(CONFIG_RTC_HCTOSYS_DEVICE); + + if (!rtc) { + pr_info("unable to open rtc device (%s)\n", + CONFIG_RTC_HCTOSYS_DEVICE); + goto err_open; + } + + err = rtc_read_time(rtc, &tm); + if (err) { + dev_err(rtc->dev.parent, + "hctosys: unable to read the hardware clock\n"); + goto err_read; + } + + tv64.tv_sec = rtc_tm_to_time64(&tm); + +#if BITS_PER_LONG == 32 + if (tv64.tv_sec > INT_MAX) { + err = -ERANGE; + goto err_read; + } +#endif + + err = do_settimeofday64(&tv64); + + dev_info(rtc->dev.parent, "setting system clock to %ptR UTC (%lld)\n", + &tm, (long long)tv64.tv_sec); + +err_read: + rtc_class_close(rtc); + +err_open: + rtc_hctosys_ret = err; + + return err; +} + + #endif #if defined(CONFIG_PM_SLEEP) && defined(CONFIG_RTC_HCTOSYS_DEVICE) @@ -375,6 +433,11 @@ int __rtc_register_device(struct module *owner, struct rtc_device *rtc) dev_info(rtc->dev.parent, "registered as %s\n", dev_name(&rtc->dev)); +#ifdef CONFIG_RTC_HCTOSYS_DEVICE + if (!strcmp(dev_name(&rtc->dev), CONFIG_RTC_HCTOSYS_DEVICE)) + rtc_hctosys(); +#endif + return 0; } EXPORT_SYMBOL_GPL(__rtc_register_device); diff --git a/drivers/rtc/hctosys.c b/drivers/rtc/hctosys.c deleted file mode 100644 index a74d0d890600..000000000000 --- a/drivers/rtc/hctosys.c +++ /dev/null @@ -1,69 +0,0 @@ -// SPDX-License-Identifier: GPL-2.0 -/* - * RTC subsystem, initialize system time on startup - * - * Copyright (C) 2005 Tower Technologies - * Author: Alessandro Zummo - */ - -#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt - -#include - -/* IMPORTANT: the RTC only stores whole seconds. It is arbitrary - * whether it stores the most close value or the value with partial - * seconds truncated. However, it is important that we use it to store - * the truncated value. This is because otherwise it is necessary, - * in an rtc sync function, to read both xtime.tv_sec and - * xtime.tv_nsec. On some processors (i.e. ARM), an atomic read - * of >32bits is not possible. So storing the most close value would - * slow down the sync API. So here we have the truncated value and - * the best guess is to add 0.5s. - */ - -static int __init rtc_hctosys(void) -{ - int err = -ENODEV; - struct rtc_time tm; - struct timespec64 tv64 = { - .tv_nsec = NSEC_PER_SEC >> 1, - }; - struct rtc_device *rtc = rtc_class_open(CONFIG_RTC_HCTOSYS_DEVICE); - - if (!rtc) { - pr_info("unable to open rtc device (%s)\n", - CONFIG_RTC_HCTOSYS_DEVICE); - goto err_open; - } - - err = rtc_read_time(rtc, &tm); - if (err) { - dev_err(rtc->dev.parent, - "hctosys: unable to read the hardware clock\n"); - goto err_read; - } - - tv64.tv_sec = rtc_tm_to_time64(&tm); - -#if BITS_PER_LONG == 32 - if (tv64.tv_sec > INT_MAX) { - err = -ERANGE; - goto err_read; - } -#endif - - err = do_settimeofday64(&tv64); - - dev_info(rtc->dev.parent, "setting system clock to %ptR UTC (%lld)\n", - &tm, (long long)tv64.tv_sec); - -err_read: - rtc_class_close(rtc); - -err_open: - rtc_hctosys_ret = err; - - return err; -} - -late_initcall(rtc_hctosys);