From patchwork Sat Aug 13 13:10:33 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: =?utf-8?q?Mateusz_Jo=C5=84czyk?= X-Patchwork-Id: 1666056 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@bilbo.ozlabs.org Authentication-Results: bilbo.ozlabs.org; dkim=pass (1024-bit key; unprotected) header.d=o2.pl header.i=@o2.pl header.a=rsa-sha256 header.s=1024a header.b=HQIdpTjB; 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 4M4h1j3Tk8z9sGR for ; Sat, 13 Aug 2022 23:18:17 +1000 (AEST) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S237284AbiHMNSM (ORCPT ); Sat, 13 Aug 2022 09:18:12 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:55570 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S235278AbiHMNSL (ORCPT ); Sat, 13 Aug 2022 09:18:11 -0400 X-Greylist: delayed 399 seconds by postgrey-1.37 at lindbergh.monkeyblade.net; Sat, 13 Aug 2022 06:18:10 PDT Received: from mx-out.tlen.pl (mx-out.tlen.pl [193.222.135.140]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id C4AED2CE26 for ; Sat, 13 Aug 2022 06:18:10 -0700 (PDT) Received: (wp-smtpd smtp.tlen.pl 1732 invoked from network); 13 Aug 2022 15:11:27 +0200 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=o2.pl; s=1024a; t=1660396288; bh=UdiZebRcg7fc1qTSTF83hQnkuJij3fTbRXrB9lBscoY=; h=From:To:Cc:Subject; b=HQIdpTjBgwRcucFznis3z5PruGpJxj/suy4bBX0V07Xdc9SQ2tmV+k5qLFIId8SFA iYTkUjFP8VqbyGKckUi+jOKTZVFWKWV3cQvVBmz2woADUdKhhfUfknoLrDIFr7FCyL 9IFtzRb5nEAb7BFGfDgCnMxwRkky6pPoQ/tVHuVc= Received: from aaeq146.neoplus.adsl.tpnet.pl (HELO localhost.localdomain) (mat.jonczyk@o2.pl@[83.4.120.146]) (envelope-sender ) by smtp.tlen.pl (WP-SMTPD) with SMTP for ; 13 Aug 2022 15:11:27 +0200 From: =?utf-8?q?Mateusz_Jo=C5=84czyk?= To: linux-kernel@vger.kernel.org, linux-rtc@vger.kernel.org Cc: =?utf-8?q?Mateusz_Jo=C5=84czyk?= , Thomas Gleixner , Ingo Molnar , Borislav Petkov , Dave Hansen , x86@kernel.org, "H. Peter Anvin" , Alessandro Zummo , Alexandre Belloni Subject: [PATCH v4 1/2] x86/rtc: rewrite mach_get_cmos_time to delete duplicated code Date: Sat, 13 Aug 2022 15:10:33 +0200 Message-Id: <20220813131034.768527-1-mat.jonczyk@o2.pl> X-Mailer: git-send-email 2.25.1 MIME-Version: 1.0 X-WP-MailID: 9b9ecbffff635b5a35b94a86c5d74122 X-WP-AV: skaner antywirusowy Poczty o2 X-WP-SPAM: NO 0000000 [kfP0] X-Spam-Status: No, score=-2.1 required=5.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF,FREEMAIL_FROM,RCVD_IN_MSPIKE_H2, SPF_HELO_NONE,SPF_PASS,T_SCC_BODY_TEXT_LINE autolearn=unavailable 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 There are functions in drivers/rtc/rtc-mc146818-lib.c that handle reading from / writing to the CMOS RTC clock. mach_get_cmos_time() in arch/x86/kernel/rtc.c did not use them and was mostly a duplicate of mc146818_get_time(). Modify mach_get_cmos_time() to use mc146818_get_time() and remove the duplicated code. mach_get_cmos_time() used a different algorithm than mc146818_get_time(), but these functions are equivalent. The major differences are: - mc146818_get_time() is better refined and handles various edge conditions, - when the UIP ("Update in progress") bit of the RTC is set, mach_get_cmos_time() was busy waiting with cpu_relax() while mc146818_get_time() is using mdelay(1) in every loop iteration. (However, there is my commit merged for Linux 5.20 / 6.0 to decrease this period to 100us: commit d2a632a8a117 ("rtc: mc146818-lib: reduce RTC_UIP polling period") ), - mach_get_cmos_time() assumed that the RTC year is >= 2000, which may not be true on some old boxes with a dead battery, - mach_get_cmos_time() was holding the rtc_lock for a long time and could hang if the RTC is broken or not present. The RTC writing counterpart, mach_set_rtc_mmss() is already using mc146818_get_time() from drivers/rtc. This was done in commit 3195ef59cb42 ("x86: Do full rtc synchronization with ntp") It appears that mach_get_cmos_time() was simply forgotten. mach_get_cmos_time() is really used only in read_persistent_clock64(), which is called only in a few places in kernel/time/timekeeping.c . Signed-off-by: Mateusz Jończyk Cc: Thomas Gleixner Cc: Ingo Molnar Cc: Borislav Petkov Cc: Dave Hansen Cc: x86@kernel.org Cc: "H. Peter Anvin" Cc: Alessandro Zummo Cc: Alexandre Belloni Acked-by: Alexandre Belloni --- v2: - use pr_err() in place of pr_err_ratelimited(). mach_get_cmos_time() is not called frequently, so ratelimiting is not necessary. - tweak the commit description. v3: - update the commit description, - drop the cover letter. v4: - slightly update the commit description. Tested on 3 computers (on top of 5.19.0-rc5), on 5.19.1 tested less strictly. --- arch/x86/kernel/rtc.c | 59 +++++-------------------------------------- 1 file changed, 7 insertions(+), 52 deletions(-) diff --git a/arch/x86/kernel/rtc.c b/arch/x86/kernel/rtc.c index 586f718b8e95..1cadc8a15267 100644 --- a/arch/x86/kernel/rtc.c +++ b/arch/x86/kernel/rtc.c @@ -4,11 +4,8 @@ */ #include #include -#include -#include #include #include -#include #include #include @@ -20,15 +17,12 @@ /* * This is a special lock that is owned by the CPU and holds the index * register we are working with. It is required for NMI access to the - * CMOS/RTC registers. See include/asm-i386/mc146818rtc.h for details. + * CMOS/RTC registers. See arch/x86/include/asm/mc146818rtc.h for details. */ volatile unsigned long cmos_lock; EXPORT_SYMBOL(cmos_lock); #endif /* CONFIG_X86_32 */ -/* For two digit years assume time is always after that */ -#define CMOS_YEARS_OFFS 2000 - DEFINE_SPINLOCK(rtc_lock); EXPORT_SYMBOL(rtc_lock); @@ -62,8 +56,7 @@ int mach_set_rtc_mmss(const struct timespec64 *now) void mach_get_cmos_time(struct timespec64 *now) { - unsigned int status, year, mon, day, hour, min, sec, century = 0; - unsigned long flags; + struct rtc_time tm; /* * If pm_trace abused the RTC as storage, set the timespec to 0, @@ -74,51 +67,13 @@ void mach_get_cmos_time(struct timespec64 *now) return; } - spin_lock_irqsave(&rtc_lock, flags); - - /* - * If UIP is clear, then we have >= 244 microseconds before - * RTC registers will be updated. Spec sheet says that this - * is the reliable way to read RTC - registers. If UIP is set - * then the register access might be invalid. - */ - while ((CMOS_READ(RTC_FREQ_SELECT) & RTC_UIP)) - cpu_relax(); - - sec = CMOS_READ(RTC_SECONDS); - min = CMOS_READ(RTC_MINUTES); - hour = CMOS_READ(RTC_HOURS); - day = CMOS_READ(RTC_DAY_OF_MONTH); - mon = CMOS_READ(RTC_MONTH); - year = CMOS_READ(RTC_YEAR); - -#ifdef CONFIG_ACPI - if (acpi_gbl_FADT.header.revision >= FADT2_REVISION_ID && - acpi_gbl_FADT.century) - century = CMOS_READ(acpi_gbl_FADT.century); -#endif - - status = CMOS_READ(RTC_CONTROL); - WARN_ON_ONCE(RTC_ALWAYS_BCD && (status & RTC_DM_BINARY)); - - spin_unlock_irqrestore(&rtc_lock, flags); - - if (RTC_ALWAYS_BCD || !(status & RTC_DM_BINARY)) { - sec = bcd2bin(sec); - min = bcd2bin(min); - hour = bcd2bin(hour); - day = bcd2bin(day); - mon = bcd2bin(mon); - year = bcd2bin(year); + if (mc146818_get_time(&tm)) { + pr_err("Unable to read current time from RTC\n"); + now->tv_sec = now->tv_nsec = 0; + return; } - if (century) { - century = bcd2bin(century); - year += century * 100; - } else - year += CMOS_YEARS_OFFS; - - now->tv_sec = mktime64(year, mon, day, hour, min, sec); + now->tv_sec = rtc_tm_to_time64(&tm); now->tv_nsec = 0; } From patchwork Sat Aug 13 13:10:34 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: =?utf-8?q?Mateusz_Jo=C5=84czyk?= X-Patchwork-Id: 1666057 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@bilbo.ozlabs.org Authentication-Results: bilbo.ozlabs.org; dkim=pass (1024-bit key; unprotected) header.d=o2.pl header.i=@o2.pl header.a=rsa-sha256 header.s=1024a header.b=kubk1nc3; 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 4M4h211DWYz9sGR for ; Sat, 13 Aug 2022 23:18:33 +1000 (AEST) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S239447AbiHMNSb (ORCPT ); Sat, 13 Aug 2022 09:18:31 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:55644 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S235278AbiHMNSa (ORCPT ); Sat, 13 Aug 2022 09:18:30 -0400 Received: from mx-out.tlen.pl (mx-out.tlen.pl [193.222.135.140]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 99DE42CE26 for ; Sat, 13 Aug 2022 06:18:29 -0700 (PDT) Received: (wp-smtpd smtp.tlen.pl 21285 invoked from network); 13 Aug 2022 15:11:45 +0200 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=o2.pl; s=1024a; t=1660396305; bh=K7sZyZBLB32TVPnHXHDCJNKvmqNVMgAxHvI8I7Fg41c=; h=From:To:Cc:Subject; b=kubk1nc3wUo0ZfphY/CIG2BbVWCb2gESwXDc4+BKEGykD7yNODDLRwVpUN/KQflpL 2xlhy53XZtrSnvg2he73C31luSx/r4vlWav9YCkHFdRHV2TdTFn/vzNNQLQOKHHwAr WoR+AMqZbnVAR7om1hKUxoBG1kehX3RxHuUxBlJM= Received: from aaeq146.neoplus.adsl.tpnet.pl (HELO localhost.localdomain) (mat.jonczyk@o2.pl@[83.4.120.146]) (envelope-sender ) by smtp.tlen.pl (WP-SMTPD) with SMTP for ; 13 Aug 2022 15:11:45 +0200 From: =?utf-8?q?Mateusz_Jo=C5=84czyk?= To: linux-kernel@vger.kernel.org, linux-rtc@vger.kernel.org Cc: =?utf-8?q?Mateusz_Jo=C5=84czyk?= , Thomas Gleixner , Ingo Molnar , Borislav Petkov , Dave Hansen , x86@kernel.org, "H. Peter Anvin" , Alexandre Belloni , Brijesh Singh , "Kirill A. Shutemov" , Jason Gunthorpe Subject: [PATCH v4 2/2] x86/rtc: rename mach_set_rtc_mmss Date: Sat, 13 Aug 2022 15:10:34 +0200 Message-Id: <20220813131034.768527-2-mat.jonczyk@o2.pl> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20220813131034.768527-1-mat.jonczyk@o2.pl> References: <20220813131034.768527-1-mat.jonczyk@o2.pl> MIME-Version: 1.0 X-WP-MailID: 4f51fed1a705c1695ebe1c3fd6fe0912 X-WP-AV: skaner antywirusowy Poczty o2 X-WP-SPAM: NO 0000000 [EcNU] X-Spam-Status: No, score=-2.1 required=5.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF,FREEMAIL_FROM,RCVD_IN_MSPIKE_H2, SPF_HELO_NONE,SPF_PASS,T_SCC_BODY_TEXT_LINE autolearn=unavailable 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 Once upon a time, before commit 3195ef59cb42 ("x86: Do full rtc synchronization with ntp") in 2013, the function set only the minute and seconds registers of the CMOS RTC. This is no longer true, so rename the function to mach_set_cmos_time. Signed-off-by: Mateusz Jończyk Cc: Thomas Gleixner Cc: Ingo Molnar Cc: Borislav Petkov Cc: Dave Hansen Cc: x86@kernel.org Cc: "H. Peter Anvin" Cc: Alexandre Belloni Cc: Brijesh Singh Cc: "Kirill A. Shutemov" Cc: Jason Gunthorpe --- v3: - add more people to the Cc list. --- arch/x86/include/asm/mc146818rtc.h | 2 +- arch/x86/kernel/rtc.c | 4 ++-- arch/x86/kernel/x86_init.c | 2 +- 3 files changed, 4 insertions(+), 4 deletions(-) diff --git a/arch/x86/include/asm/mc146818rtc.h b/arch/x86/include/asm/mc146818rtc.h index 97198001e567..6115bb3d5795 100644 --- a/arch/x86/include/asm/mc146818rtc.h +++ b/arch/x86/include/asm/mc146818rtc.h @@ -95,7 +95,7 @@ static inline unsigned char current_lock_cmos_reg(void) unsigned char rtc_cmos_read(unsigned char addr); void rtc_cmos_write(unsigned char val, unsigned char addr); -extern int mach_set_rtc_mmss(const struct timespec64 *now); +extern int mach_set_cmos_time(const struct timespec64 *now); extern void mach_get_cmos_time(struct timespec64 *now); #define RTC_IRQ 8 diff --git a/arch/x86/kernel/rtc.c b/arch/x86/kernel/rtc.c index 1cadc8a15267..349046434513 100644 --- a/arch/x86/kernel/rtc.c +++ b/arch/x86/kernel/rtc.c @@ -27,13 +27,13 @@ DEFINE_SPINLOCK(rtc_lock); EXPORT_SYMBOL(rtc_lock); /* - * In order to set the CMOS clock precisely, set_rtc_mmss has to be + * In order to set the CMOS clock precisely, mach_set_cmos_time has to be * called 500 ms after the second nowtime has started, because when * nowtime is written into the registers of the CMOS clock, it will * jump to the next second precisely 500 ms later. Check the Motorola * MC146818A or Dallas DS12887 data sheet for details. */ -int mach_set_rtc_mmss(const struct timespec64 *now) +int mach_set_cmos_time(const struct timespec64 *now) { unsigned long long nowtime = now->tv_sec; struct rtc_time tm; diff --git a/arch/x86/kernel/x86_init.c b/arch/x86/kernel/x86_init.c index e84ee5cdbd8c..57353519bc11 100644 --- a/arch/x86/kernel/x86_init.c +++ b/arch/x86/kernel/x86_init.c @@ -138,7 +138,7 @@ struct x86_platform_ops x86_platform __ro_after_init = { .calibrate_cpu = native_calibrate_cpu_early, .calibrate_tsc = native_calibrate_tsc, .get_wallclock = mach_get_cmos_time, - .set_wallclock = mach_set_rtc_mmss, + .set_wallclock = mach_set_cmos_time, .iommu_shutdown = iommu_shutdown_noop, .is_untracked_pat_range = is_ISA_range, .nmi_init = default_nmi_init,