From nobody Wed Jul 1 14:31:26 2026 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 85297C433F5 for ; Mon, 20 Dec 2021 17:42:21 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S239923AbhLTRmU (ORCPT ); Mon, 20 Dec 2021 12:42:20 -0500 Received: from foss.arm.com ([217.140.110.172]:60388 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233373AbhLTRmS (ORCPT ); Mon, 20 Dec 2021 12:42:18 -0500 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id D5676D6E; Mon, 20 Dec 2021 09:42:17 -0800 (PST) Received: from e120937-lin.home (unknown [172.31.20.19]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 7DB363F774; Mon, 20 Dec 2021 09:42:16 -0800 (PST) From: Cristian Marussi To: linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org Cc: sudeep.holla@arm.com, f.fainelli@gmail.com, souvik.chakravarty@arm.com, nicola.mazzucato@arm.com, Cristian Marussi Subject: [RFC PATCH 1/2] firmware: arm_scmi: Filter out negative results on scmi_reading_get Date: Mon, 20 Dec 2021 17:41:54 +0000 Message-Id: <20211220174155.40239-2-cristian.marussi@arm.com> X-Mailer: git-send-email 2.17.1 In-Reply-To: <20211220174155.40239-1-cristian.marussi@arm.com> References: <20211220174155.40239-1-cristian.marussi@arm.com> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" When the backing SCMI Platform supports a Sensor protocol whose version is greater than SCMI v2.0 (0x10000), the underlying SCMI SENSOR_READING_GET command will report sensors readings no more as unsigned but as signed values. A new scmi_reading_get_timestamped operation was added to properly handle this and other changes like timestamps and multi-axis sensors; on the other side the Sensor scmi_reading_get protocol operation was kepts as it was for backward compatibility and so it stil reports values as unsigned, but no check was added to detect the situation in which a newer FW could try to report negative values over an unsigned quantity. Filter out negative values in scmi_reading_get, reporting an error, when the SCMI FW version is greater than V2.0 and a negative value has been received. Reported-by: Nicola Mazzucato Signed-off-by: Cristian Marussi --- Note that, till now, HWMON SCMI driver was silently interpreting u64 as s64, so after this change whenever a FW >2.0 is used it won't be possible anymore to report negative values in HWMON. --- drivers/firmware/arm_scmi/sensors.c | 8 ++++++++ 1 file changed, 8 insertions(+) diff --git a/drivers/firmware/arm_scmi/sensors.c b/drivers/firmware/arm_scm= i/sensors.c index cdbb287bd8bc..f3952f1d9f61 100644 --- a/drivers/firmware/arm_scmi/sensors.c +++ b/drivers/firmware/arm_scmi/sensors.c @@ -730,6 +730,14 @@ static int scmi_sensor_reading_get(const struct scmi_p= rotocol_handle *ph, *value =3D get_unaligned_le64(t->rx.buf); } =20 + if (!ret && si->version > SCMIv2_SENSOR_PROTOCOL && *value & BIT(63)) { + dev_warn_once(ph->dev, + "SCMI FW Sensor version:0x%X reported negative value %ld\n", + si->version, (long)*value); + *value =3D 0; + ret =3D -EIO; + } + ph->xops->xfer_put(ph, t); return ret; } --=20 2.17.1 From nobody Wed Jul 1 14:31:26 2026 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 48901C433EF for ; Mon, 20 Dec 2021 17:42:24 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S240258AbhLTRmX (ORCPT ); Mon, 20 Dec 2021 12:42:23 -0500 Received: from foss.arm.com ([217.140.110.172]:60398 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S239737AbhLTRmT (ORCPT ); Mon, 20 Dec 2021 12:42:19 -0500 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 53184ED1; Mon, 20 Dec 2021 09:42:19 -0800 (PST) Received: from e120937-lin.home (unknown [172.31.20.19]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 164563F774; Mon, 20 Dec 2021 09:42:17 -0800 (PST) From: Cristian Marussi To: linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org Cc: sudeep.holla@arm.com, f.fainelli@gmail.com, souvik.chakravarty@arm.com, nicola.mazzucato@arm.com, Cristian Marussi Subject: [RFC PATCH 2/2] hwmon: (scmi) Filter out results wrongly interpreted as negatives Date: Mon, 20 Dec 2021 17:41:55 +0000 Message-Id: <20211220174155.40239-3-cristian.marussi@arm.com> X-Mailer: git-send-email 2.17.1 In-Reply-To: <20211220174155.40239-1-cristian.marussi@arm.com> References: <20211220174155.40239-1-cristian.marussi@arm.com> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" SCMI Sensor scmi_reading_get interface can report only unsigned values while hwmon_ops.read allows for signed negative values to be passed on: this has the undesired side effect of silently interpreting as negative any big-enough positive reading reported by the SCMI interface. Filter out such big positives reporting an error. Signed-off-by: Cristian Marussi --- drivers/hwmon/scmi-hwmon.c | 14 ++++++++++++++ 1 file changed, 14 insertions(+) diff --git a/drivers/hwmon/scmi-hwmon.c b/drivers/hwmon/scmi-hwmon.c index b1329a58ce40..0924d1b8a9ce 100644 --- a/drivers/hwmon/scmi-hwmon.c +++ b/drivers/hwmon/scmi-hwmon.c @@ -73,10 +73,24 @@ static int scmi_hwmon_read(struct device *dev, enum hwm= on_sensor_types type, struct scmi_sensors *scmi_sensors =3D dev_get_drvdata(dev); =20 sensor =3D *(scmi_sensors->info[type] + channel); + /* + * Can fail with EIO if the backing SCMI Sensor FW version tried to + * report a negative value. + */ ret =3D sensor_ops->reading_get(scmi_sensors->ph, sensor->id, &value); if (ret) return ret; =20 + /* + * Cannot accept either valid positive values so big that would be + * interpreted as negative by HWMON signed long *val return value. + */ + if (value & BIT(63)) { + dev_warn_once(dev, + "Reported unsigned value too big.\n"); + return -EIO; + } + ret =3D scmi_hwmon_scale(sensor, &value); if (!ret) *val =3D value; --=20 2.17.1