From mboxrd@z Thu Jan 1 00:00:00 1970 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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 367DFC04FDE for ; Mon, 12 Dec 2022 13:13:56 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232085AbiLLNNy (ORCPT ); Mon, 12 Dec 2022 08:13:54 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:40910 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231854AbiLLNNZ (ORCPT ); Mon, 12 Dec 2022 08:13:25 -0500 Received: from dfw.source.kernel.org (dfw.source.kernel.org [IPv6:2604:1380:4641:c500::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 5EAE6BF9 for ; Mon, 12 Dec 2022 05:13:19 -0800 (PST) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id EFC0B61049 for ; Mon, 12 Dec 2022 13:13:18 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id F0B6DC433EF; Mon, 12 Dec 2022 13:13:17 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1670850798; bh=DqKM849x7gt3PjeNUUtRJHZ1GNC+B3dQOWwls24FMt0=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=sQBP716JQSWb2ddwpI0WQf9prmu4X+aSUiEb+ZIby19M9epLXWFV81qWWzU8bOv// GIXesncXazYOpodC3+EByh0UEdy3SEhHgLRT0cahJClj2J7i5HYvsfUjF+tGJBHAew hyx8p+wqkbPhEPN2G/7Hj5/67dA9xd0uva1xD83g= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, =?UTF-8?q?Micka=C3=ABl=20Sala=C3=BCn?= , Thomas Gleixner , =?UTF-8?q?Micka=C3=ABl=20Sala=C3=BCn?= , Alexandre Belloni , Sasha Levin Subject: [PATCH 5.10 031/106] rtc: mc146818: Detect and handle broken RTCs Date: Mon, 12 Dec 2022 14:09:34 +0100 Message-Id: <20221212130926.209972761@linuxfoundation.org> X-Mailer: git-send-email 2.38.1 In-Reply-To: <20221212130924.863767275@linuxfoundation.org> References: <20221212130924.863767275@linuxfoundation.org> User-Agent: quilt/0.67 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Thomas Gleixner [ Upstream commit 211e5db19d15a721b2953ea54b8f26c2963720eb ] The recent fix for handling the UIP bit unearthed another issue in the RTC code. If the RTC is advertised but the readout is straight 0xFF because it's not available, the old code just proceeded with crappy values, but the new code hangs because it waits for the UIP bit to become low. Add a sanity check in the RTC CMOS probe function which reads the RTC_VALID register (Register D) which should have bit 0-6 cleared. If that's not the case then fail to register the CMOS. Add the same check to mc146818_get_time(), warn once when the condition is true and invalidate the rtc_time data. Reported-by: Mickaël Salaün Signed-off-by: Thomas Gleixner Tested-by: Mickaël Salaün Acked-by: Alexandre Belloni Link: https://lore.kernel.org/r/87tur3fx7w.fsf@nanos.tec.linutronix.de Stable-dep-of: cd17420ebea5 ("rtc: cmos: avoid UIP when writing alarm time") Signed-off-by: Sasha Levin --- drivers/rtc/rtc-cmos.c | 8 ++++++++ drivers/rtc/rtc-mc146818-lib.c | 7 +++++++ 2 files changed, 15 insertions(+) diff --git a/drivers/rtc/rtc-cmos.c b/drivers/rtc/rtc-cmos.c index 58c6382a2807..cce4b62ffdd0 100644 --- a/drivers/rtc/rtc-cmos.c +++ b/drivers/rtc/rtc-cmos.c @@ -808,6 +808,14 @@ cmos_do_probe(struct device *dev, struct resource *ports, int rtc_irq) spin_lock_irq(&rtc_lock); + /* Ensure that the RTC is accessible. Bit 0-6 must be 0! */ + if ((CMOS_READ(RTC_VALID) & 0x7f) != 0) { + spin_unlock_irq(&rtc_lock); + dev_warn(dev, "not accessible\n"); + retval = -ENXIO; + goto cleanup1; + } + if (!(flags & CMOS_RTC_FLAGS_NOFREQ)) { /* force periodic irq to CMOS reset default of 1024Hz; * diff --git a/drivers/rtc/rtc-mc146818-lib.c b/drivers/rtc/rtc-mc146818-lib.c index 8364e4141670..7f01dc41271d 100644 --- a/drivers/rtc/rtc-mc146818-lib.c +++ b/drivers/rtc/rtc-mc146818-lib.c @@ -21,6 +21,13 @@ unsigned int mc146818_get_time(struct rtc_time *time) again: spin_lock_irqsave(&rtc_lock, flags); + /* Ensure that the RTC is accessible. Bit 0-6 must be 0! */ + if (WARN_ON_ONCE((CMOS_READ(RTC_VALID) & 0x7f) != 0)) { + spin_unlock_irqrestore(&rtc_lock, flags); + memset(time, 0xff, sizeof(*time)); + return 0; + } + /* * Check whether there is an update in progress during which the * readout is unspecified. The maximum update time is ~2ms. Poll -- 2.35.1