From mboxrd@z Thu Jan 1 00:00:00 1970 Delivery-date: Tue, 18 Mar 2025 12:12:17 +0100 Received: from metis.whiteo.stw.pengutronix.de ([2a0a:edc0:2:b01:1d::104]) by lore.white.stw.pengutronix.de with esmtps (TLS1.3) tls TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 (Exim 4.96) (envelope-from ) id 1tuUrp-0010rT-2u for lore@lore.pengutronix.de; Tue, 18 Mar 2025 12:12:17 +0100 Received: from bombadil.infradead.org ([2607:7c80:54:3::133]) by metis.whiteo.stw.pengutronix.de with esmtps (TLS1.3:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.92) (envelope-from ) id 1tuUro-0003xG-LD for lore@pengutronix.de; Tue, 18 Mar 2025 12:12:17 +0100 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:List-Subscribe:List-Help :List-Post:List-Archive:List-Unsubscribe:List-Id:In-Reply-To:Content-Type: MIME-Version:References:Message-ID:Subject:Cc:To:From:Date:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=cfyi3EQz/bj0XmCKBzFdAF//s2MCjrvXtlaDfpebOIc=; b=FZe2JfTOos/quc/G72WTtaYARh ptMZpQ32ihyu0T4wBRnuxYqcndGAxjWpXjxL51chi8aBcovklXsfV1iFjQiwoa9NM2mUlKMTcXOxp 7dsWug7VtJTX0p7UErLwJTA5dfJXA8xkkjpjy9F/OxocQ11dDo+ecjCn2BcW8uS5DNPq682kL93eR BLud3LU6Z7YLjNB2qiWybIWe/siZX4xvMPTT/6AL9P4jvx1HAtKUECF/FDzJABNWCmXQLtF3HB0z0 pPPvT0bImTG3FoeuufvY/AweEv0S994ui6bMJskSNMJW7R5xKylmCV6ol9uwulDO3anntVc3p7xDj pv/D4Tvg==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.98 #2 (Red Hat Linux)) id 1tuUrM-00000005fGS-3b7t; Tue, 18 Mar 2025 11:11:48 +0000 Received: from metis.whiteo.stw.pengutronix.de ([2a0a:edc0:2:b01:1d::104]) by bombadil.infradead.org with esmtps (Exim 4.98 #2 (Red Hat Linux)) id 1tuUkO-00000005del-05wP for barebox@lists.infradead.org; Tue, 18 Mar 2025 11:04:37 +0000 Received: from drehscheibe.grey.stw.pengutronix.de ([2a0a:edc0:0:c01:1d::a2]) by metis.whiteo.stw.pengutronix.de with esmtps (TLS1.3:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.92) (envelope-from ) id 1tuUkM-0002uS-CT; Tue, 18 Mar 2025 12:04:34 +0100 Received: from pty.whiteo.stw.pengutronix.de ([2a0a:edc0:2:b01:1d::c5]) by drehscheibe.grey.stw.pengutronix.de with esmtps (TLS1.3) tls TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 (Exim 4.96) (envelope-from ) id 1tuUkL-000Pr5-2V; Tue, 18 Mar 2025 12:04:34 +0100 Received: from sha by pty.whiteo.stw.pengutronix.de with local (Exim 4.96) (envelope-from ) id 1tuUkM-0030A1-0G; Tue, 18 Mar 2025 12:04:34 +0100 Date: Tue, 18 Mar 2025 12:04:34 +0100 From: Sascha Hauer To: Ahmad Fatoum Cc: barebox@lists.infradead.org Message-ID: References: <20250318082507.419785-1-a.fatoum@pengutronix.de> <20250318082507.419785-3-a.fatoum@pengutronix.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20250318082507.419785-3-a.fatoum@pengutronix.de> X-Sent-From: Pengutronix Hildesheim X-URL: http://www.pengutronix.de/ X-Accept-Language: de,en X-Accept-Content-Type: text/plain X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20250318_040436_060735_CC497451 X-CRM114-Status: GOOD ( 38.63 ) X-BeenThere: barebox@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "barebox" X-SA-Exim-Connect-IP: 2607:7c80:54:3::133 X-SA-Exim-Mail-From: barebox-bounces+lore=pengutronix.de@lists.infradead.org X-Spam-Checker-Version: SpamAssassin 3.4.2 (2018-09-13) on metis.whiteo.stw.pengutronix.de X-Spam-Level: X-Spam-Status: No, score=-5.4 required=4.0 tests=AWL,BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,RCVD_IN_DNSWL_MED,SPF_HELO_NONE,SPF_NONE autolearn=unavailable autolearn_force=no version=3.4.2 Subject: Re: [PATCH 3/4] amba: support masking data abort during identification X-SA-Exim-Version: 4.2.1 (built Wed, 08 May 2019 21:11:16 +0000) X-SA-Exim-Scanned: Yes (on metis.whiteo.stw.pengutronix.de) On Tue, Mar 18, 2025 at 09:25:06AM +0100, Ahmad Fatoum wrote: > Registration of an AMBA device requires reading its pid and cid > registers after turning on the device. This is the first I/O done to the > device and may end up crashing if the device tree doesn't describe > the correct clock and power domains or if a previous boot stage > should've enabled them, but didn't. > > This is not a likely issue, but when it happens it crashes the system > annoyingly early during device tree populating. > > Add a symbol that masks the data abort exception around the > identification code to turn the crash into an error message instead. Do we need to make this optional? I could imagine I find out about the existence of this option only after having traced the issue down to the exact lines of code in which case I won't need the option anymore. Sascha > > Signed-off-by: Ahmad Fatoum > --- > drivers/amba/Kconfig | 19 +++++++++++++++++++ > drivers/amba/bus.c | 12 +++++++++++- > 2 files changed, 30 insertions(+), 1 deletion(-) > > diff --git a/drivers/amba/Kconfig b/drivers/amba/Kconfig > index 444d4ce7435c..be5e053f4b84 100644 > --- a/drivers/amba/Kconfig > +++ b/drivers/amba/Kconfig > @@ -1,3 +1,22 @@ > # SPDX-License-Identifier: GPL-2.0-only > config ARM_AMBA > bool > + > +config ARM_AMBA_DABT_MASK > + bool > + prompt "Mask data abort while identifying AMBA devices" if COMPILE_TEST > + depends on ARM_AMBA && ARCH_HAS_DATA_ABORT_MASK > + help > + Registration of an AMBA device requires reading its pid and cid > + registers after turning on the device, which can involve enabling > + clocks, deasserting resets and powering on power domains. > + In some cases, these resources are not available to barebox running > + in the normal world and thus need to be setup by a previous > + stage bootloader running in the secure world. > + If such setup doesn't happen, accessing devices may lead to > + a data abort or complete system hang. > + > + As a workaround for the former case, this option can be enabled > + to gracefully handle data aborts during readout of the PID/CID > + registers. The proper solution is fixing your first stage > + bootloader or allow barebox access to the missing resources. > diff --git a/drivers/amba/bus.c b/drivers/amba/bus.c > index 6463366fafc5..5ed8336e6124 100644 > --- a/drivers/amba/bus.c > +++ b/drivers/amba/bus.c > @@ -10,6 +10,7 @@ > #include > #include > #include > +#include > > #define to_amba_driver(d) container_of(d, struct amba_driver, drv) > > @@ -132,6 +133,9 @@ int amba_device_add(struct amba_device *dev) > if (ret == 0) { > u32 pid, cid; > > + if (IS_ENABLED(CONFIG_ARM_AMBA_DABT_MASK)) > + data_abort_mask(); > + > /* > * Read pid and cid based on size of resource > * they are located at end of region > @@ -139,8 +143,14 @@ int amba_device_add(struct amba_device *dev) > pid = amba_device_get_pid(tmp, size); > cid = amba_device_get_cid(tmp, size); > > - if (cid == AMBA_CID) > + if (IS_ENABLED(CONFIG_ARM_AMBA_DABT_MASK) && data_abort_unmask()) { > + dev_err(amba_bustype.dev, > + "data abort during MMIO read of PID/CID for %pOF\n", > + dev->dev.of_node); > + ret = -EFAULT; > + } else if (cid == AMBA_CID) { > dev->periphid = pid; > + } > > if (!dev->periphid) > ret = -ENODEV; > -- > 2.39.5 > > > -- Pengutronix e.K. | | Steuerwalder Str. 21 | http://www.pengutronix.de/ | 31137 Hildesheim, Germany | Phone: +49-5121-206917-0 | Amtsgericht Hildesheim, HRA 2686 | Fax: +49-5121-206917-5555 |