From patchwork Wed Apr 13 21:00:19 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Jeffrey Hugo X-Patchwork-Id: 12812632 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 EAA54C433EF for ; Wed, 13 Apr 2022 21:00:45 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S238031AbiDMVDF (ORCPT ); Wed, 13 Apr 2022 17:03:05 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:44728 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S237823AbiDMVDE (ORCPT ); Wed, 13 Apr 2022 17:03:04 -0400 Received: from alexa-out-sd-02.qualcomm.com (alexa-out-sd-02.qualcomm.com [199.106.114.39]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 8FD2C6A02C; Wed, 13 Apr 2022 14:00:42 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=quicinc.com; i=@quicinc.com; q=dns/txt; s=qcdkim; t=1649883642; x=1681419642; h=from:to:cc:subject:date:message-id:mime-version: content-transfer-encoding; bh=TYcb4p1NHchumQzV88t1cTQVvmNzj45vyo9q6CrK+2Y=; b=N/VNXYbN9uKEG2ePy71Dgn238WlTbfMFPV8k0j6iMc4AhPNIYuFkQ6A0 E2uDFSTwcqK/QnTf+5u7qSVKiCAULzu76hPn0cleHVF6GXq8OI8Ujpqbn LrPZ7eiZ6f8/8pRfrvCiHxGMRPV8emQg/wRbt1xSNruHTSvgrNWJ2hJ1M Q=; Received: from unknown (HELO ironmsg03-sd.qualcomm.com) ([10.53.140.143]) by alexa-out-sd-02.qualcomm.com with ESMTP; 13 Apr 2022 14:00:42 -0700 X-QCInternal: smtphost Received: from nasanex01c.na.qualcomm.com ([10.47.97.222]) by ironmsg03-sd.qualcomm.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 13 Apr 2022 14:00:41 -0700 Received: from nalasex01a.na.qualcomm.com (10.47.209.196) by nasanex01c.na.qualcomm.com (10.47.97.222) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.2.986.22; Wed, 13 Apr 2022 14:00:41 -0700 Received: from jhugo-lnx.qualcomm.com (10.80.80.8) by nalasex01a.na.qualcomm.com (10.47.209.196) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.2.986.22; Wed, 13 Apr 2022 14:00:40 -0700 From: Jeffrey Hugo To: , , CC: , , , Jeffrey Hugo , "Jeffrey Hugo" Subject: [PATCH v2] bus: mhi: host: Add soc_reset sysfs Date: Wed, 13 Apr 2022 15:00:19 -0600 Message-ID: <1649883619-17609-1-git-send-email-quic_jhugo@quicinc.com> X-Mailer: git-send-email 2.7.4 MIME-Version: 1.0 X-Originating-IP: [10.80.80.8] X-ClientProxiedBy: nasanex01b.na.qualcomm.com (10.46.141.250) To nalasex01a.na.qualcomm.com (10.47.209.196) Precedence: bulk List-ID: X-Mailing-List: linux-arm-msm@vger.kernel.org From: Jeffrey Hugo The MHI bus supports a standardized hardware reset, which is known as the "SoC Reset". This reset is similar to the reset sysfs for PCI devices - a hardware mechanism to reset the state back to square one. The MHI SoC Reset is described in the spec as a reset of last resort. If some unrecoverable error has occurred where other resets have failed, SoC Reset is the "big hammer" that ungracefully resets the device. This is effectivly the same as yanking the power on the device, and reapplying it. However, depending on the nature of the particular issue, the underlying transport link may remain active and configured. If the link remains up, the device will flag a MHI system error early in the boot process after the reset is executed, which allows the MHI bus to process a fatal error event, and clean up appropiately. While the SoC Reset is generally intended as a means of recovery when all else has failed, it can be useful in non-error scenarios. For example, if the device loads firmware from the host filesystem, the device may need to be fully rebooted inorder to pick up the new firmware. In this scenario, the system administrator may use the soc_reset sysfs to cause the device to pick up the new firmware that the admin placed on the filesystem. Signed-off-by: Jeffrey Hugo Signed-off-by: Jeffrey Hugo Reviewed-by: Bhaumik Bhatt Reviewed-by: Manivannan Sadhasivam --- v2: Rebase Documentation/ABI/stable/sysfs-bus-mhi | 11 +++++++++++ drivers/bus/mhi/host/init.c | 14 ++++++++++++++ 2 files changed, 25 insertions(+) diff --git a/Documentation/ABI/stable/sysfs-bus-mhi b/Documentation/ABI/stable/sysfs-bus-mhi index ecfe766..306f63e 100644 --- a/Documentation/ABI/stable/sysfs-bus-mhi +++ b/Documentation/ABI/stable/sysfs-bus-mhi @@ -19,3 +19,14 @@ Description: The file holds the OEM PK Hash value of the endpoint device read without having the device power on at least once, the file will read all 0's. Users: Any userspace application or clients interested in device info. + +What: /sys/bus/mhi/devices/.../soc_reset +Date: April 2022 +KernelVersion: 5.19 +Contact: mhi@lists.linux.dev +Description: Initiates a SoC reset on the MHI controller. A SoC reset is + a reset of last resort, and will require a complete re-init. + This can be useful as a method of recovery if the device is + non-responsive, or as a means of loading new firmware as a + system administration task. + diff --git a/drivers/bus/mhi/host/init.c b/drivers/bus/mhi/host/init.c index 04c409b..e12b210 100644 --- a/drivers/bus/mhi/host/init.c +++ b/drivers/bus/mhi/host/init.c @@ -108,9 +108,23 @@ static ssize_t oem_pk_hash_show(struct device *dev, } static DEVICE_ATTR_RO(oem_pk_hash); +static ssize_t soc_reset_store(struct device *dev, + struct device_attribute *attr, + const char *buf, + size_t count) +{ + struct mhi_device *mhi_dev = to_mhi_device(dev); + struct mhi_controller *mhi_cntrl = mhi_dev->mhi_cntrl; + + mhi_soc_reset(mhi_cntrl); + return count; +} +static DEVICE_ATTR_WO(soc_reset); + static struct attribute *mhi_dev_attrs[] = { &dev_attr_serial_number.attr, &dev_attr_oem_pk_hash.attr, + &dev_attr_soc_reset.attr, NULL, }; ATTRIBUTE_GROUPS(mhi_dev);