From patchwork Fri Dec 10 20:01:31 2021 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: 1566641 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=rhxKd7P7; dkim-atps=neutral Authentication-Results: ozlabs.org; spf=pass (sender SPF authorized) smtp.mailfrom=vger.kernel.org (client-ip=23.128.96.18; helo=vger.kernel.org; envelope-from=linux-rtc-owner@vger.kernel.org; receiver=) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by bilbo.ozlabs.org (Postfix) with ESMTP id 4J9hf36DZ7z9s3q for ; Sat, 11 Dec 2021 07:02:51 +1100 (AEDT) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1344024AbhLJUG0 (ORCPT ); Fri, 10 Dec 2021 15:06:26 -0500 Received: from mx-out.tlen.pl ([193.222.135.142]:23041 "EHLO mx-out.tlen.pl" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1344018AbhLJUGT (ORCPT ); Fri, 10 Dec 2021 15:06:19 -0500 Received: (wp-smtpd smtp.tlen.pl 15013 invoked from network); 10 Dec 2021 21:02:40 +0100 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=o2.pl; s=1024a; t=1639166560; bh=EVwu6okZda3ea33LLk/febbyBMhJfcnyYZkfcTAZYN8=; h=From:To:Cc:Subject; b=rhxKd7P7gY4uYTtDNIMrXAcGmaQ12zMx4g8k7ccWAuhvkyNba9x364ZzG0G96vY58 m1FWcVAncJJYE7L4H4su6APVpYw3IGkdZ2Lx0DUs9z2102lFP0NYkBA5sbdQ8cyiUl JyFZn9FXvfsC8B5r/cu6CxUCUKUDcuoc23Wdx2oI= Received: from aaff136.neoplus.adsl.tpnet.pl (HELO localhost.localdomain) (mat.jonczyk@o2.pl@[83.4.135.136]) (envelope-sender ) by smtp.tlen.pl (WP-SMTPD) with SMTP for ; 10 Dec 2021 21:02:40 +0100 From: =?utf-8?q?Mateusz_Jo=C5=84czyk?= To: linux-rtc@vger.kernel.org, linux-kernel@vger.kernel.org Cc: =?utf-8?q?Mateusz_Jo=C5=84czyk?= , Alessandro Zummo , Alexandre Belloni Subject: [PATCH v4 9/9] rtc-cmos: avoid UIP when writing alarm time Date: Fri, 10 Dec 2021 21:01:31 +0100 Message-Id: <20211210200131.153887-10-mat.jonczyk@o2.pl> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20211210200131.153887-1-mat.jonczyk@o2.pl> References: <20211210200131.153887-1-mat.jonczyk@o2.pl> MIME-Version: 1.0 X-WP-MailID: 364add3b291a411200336a107af6cf95 X-WP-AV: skaner antywirusowy Poczty o2 X-WP-SPAM: NO 0000000 [USO0] Precedence: bulk List-ID: X-Mailing-List: linux-rtc@vger.kernel.org Some Intel chipsets disconnect the time and date RTC registers when the clock update is in progress: during this time reads may return bogus values and writes fail silently. This includes the RTC alarm registers. [1] cmos_set_alarm() did not take account for that, fix it. [1] 7th Generation Intel ® Processor Family I/O for U/Y Platforms [...] Datasheet, Volume 1 of 2 (Intel's Document Number: 334658-006) Page 208 https://www.intel.com/content/dam/www/public/us/en/documents/datasheets/7th-and-8th-gen-core-family-mobile-u-y-processor-lines-i-o-datasheet-vol-1.pdf "If a RAM read from the ten time and date bytes is attempted during an update cycle, the value read do not necessarily represent the true contents of those locations. Any RAM writes under the same conditions are ignored." Signed-off-by: Mateusz Jończyk Cc: Alessandro Zummo Cc: Alexandre Belloni --- v4: fix some checkpatch --strict warnings drivers/rtc/rtc-cmos.c | 107 +++++++++++++++++++++++++---------------- 1 file changed, 66 insertions(+), 41 deletions(-) diff --git a/drivers/rtc/rtc-cmos.c b/drivers/rtc/rtc-cmos.c index 6f47d68d2c86..7c006c2b125f 100644 --- a/drivers/rtc/rtc-cmos.c +++ b/drivers/rtc/rtc-cmos.c @@ -470,10 +470,57 @@ static int cmos_validate_alarm(struct device *dev, struct rtc_wkalrm *t) return 0; } +struct cmos_set_alarm_callback_param { + struct cmos_rtc *cmos; + unsigned char mon, mday, hrs, min, sec; + struct rtc_wkalrm *t; +}; + +/* Note: this function may be executed by mc146818_avoid_UIP() more then + * once + */ +static void cmos_set_alarm_callback(unsigned char __always_unused seconds, + void *param_in) +{ + struct cmos_set_alarm_callback_param *p = + (struct cmos_set_alarm_callback_param *)param_in; + + /* next rtc irq must not be from previous alarm setting */ + cmos_irq_disable(p->cmos, RTC_AIE); + + /* update alarm */ + CMOS_WRITE(p->hrs, RTC_HOURS_ALARM); + CMOS_WRITE(p->min, RTC_MINUTES_ALARM); + CMOS_WRITE(p->sec, RTC_SECONDS_ALARM); + + /* the system may support an "enhanced" alarm */ + if (p->cmos->day_alrm) { + CMOS_WRITE(p->mday, p->cmos->day_alrm); + if (p->cmos->mon_alrm) + CMOS_WRITE(p->mon, p->cmos->mon_alrm); + } + + if (use_hpet_alarm()) { + /* + * FIXME the HPET alarm glue currently ignores day_alrm + * and mon_alrm ... + */ + hpet_set_alarm_time(p->t->time.tm_hour, p->t->time.tm_min, + p->t->time.tm_sec); + } + + if (p->t->enabled) + cmos_irq_enable(p->cmos, RTC_AIE); +} + static int cmos_set_alarm(struct device *dev, struct rtc_wkalrm *t) { struct cmos_rtc *cmos = dev_get_drvdata(dev); - unsigned char mon, mday, hrs, min, sec, rtc_control; + struct cmos_set_alarm_callback_param p = { + .cmos = cmos, + .t = t + }; + unsigned char rtc_control; int ret; /* This not only a rtc_op, but also called directly */ @@ -484,11 +531,11 @@ static int cmos_set_alarm(struct device *dev, struct rtc_wkalrm *t) if (ret < 0) return ret; - mon = t->time.tm_mon + 1; - mday = t->time.tm_mday; - hrs = t->time.tm_hour; - min = t->time.tm_min; - sec = t->time.tm_sec; + p.mon = t->time.tm_mon + 1; + p.mday = t->time.tm_mday; + p.hrs = t->time.tm_hour; + p.min = t->time.tm_min; + p.sec = t->time.tm_sec; spin_lock_irq(&rtc_lock); rtc_control = CMOS_READ(RTC_CONTROL); @@ -496,43 +543,21 @@ static int cmos_set_alarm(struct device *dev, struct rtc_wkalrm *t) if (!(rtc_control & RTC_DM_BINARY) || RTC_ALWAYS_BCD) { /* Writing 0xff means "don't care" or "match all". */ - mon = (mon <= 12) ? bin2bcd(mon) : 0xff; - mday = (mday >= 1 && mday <= 31) ? bin2bcd(mday) : 0xff; - hrs = (hrs < 24) ? bin2bcd(hrs) : 0xff; - min = (min < 60) ? bin2bcd(min) : 0xff; - sec = (sec < 60) ? bin2bcd(sec) : 0xff; - } - - spin_lock_irq(&rtc_lock); - - /* next rtc irq must not be from previous alarm setting */ - cmos_irq_disable(cmos, RTC_AIE); - - /* update alarm */ - CMOS_WRITE(hrs, RTC_HOURS_ALARM); - CMOS_WRITE(min, RTC_MINUTES_ALARM); - CMOS_WRITE(sec, RTC_SECONDS_ALARM); - - /* the system may support an "enhanced" alarm */ - if (cmos->day_alrm) { - CMOS_WRITE(mday, cmos->day_alrm); - if (cmos->mon_alrm) - CMOS_WRITE(mon, cmos->mon_alrm); - } - - if (use_hpet_alarm()) { - /* - * FIXME the HPET alarm glue currently ignores day_alrm - * and mon_alrm ... - */ - hpet_set_alarm_time(t->time.tm_hour, t->time.tm_min, - t->time.tm_sec); + p.mon = (p.mon <= 12) ? bin2bcd(p.mon) : 0xff; + p.mday = (p.mday >= 1 && p.mday <= 31) ? bin2bcd(p.mday) : 0xff; + p.hrs = (p.hrs < 24) ? bin2bcd(p.hrs) : 0xff; + p.min = (p.min < 60) ? bin2bcd(p.min) : 0xff; + p.sec = (p.sec < 60) ? bin2bcd(p.sec) : 0xff; } - if (t->enabled) - cmos_irq_enable(cmos, RTC_AIE); - - spin_unlock_irq(&rtc_lock); + /* + * Some Intel chipsets disconnect the alarm registers when the clock + * update is in progress - during this time writes fail silently. + * + * Use mc146818_avoid_UIP() to avoid this. + */ + if (!mc146818_avoid_UIP(cmos_set_alarm_callback, &p)) + return -EIO; cmos->alarm_expires = rtc_tm_to_time64(&t->time);