From patchwork Mon Nov 16 22:46:20 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Hemant Kumar X-Patchwork-Id: 11911013 X-Patchwork-Delegate: kuba@kernel.org Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-12.7 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id EDC23C64E7D for ; Mon, 16 Nov 2020 22:46:57 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id BBFF024170 for ; Mon, 16 Nov 2020 22:46:57 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=mg.codeaurora.org header.i=@mg.codeaurora.org header.b="asWsCBJY" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730758AbgKPWqu (ORCPT ); Mon, 16 Nov 2020 17:46:50 -0500 Received: from z5.mailgun.us ([104.130.96.5]:10888 "EHLO z5.mailgun.us" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1730534AbgKPWql (ORCPT ); Mon, 16 Nov 2020 17:46:41 -0500 DKIM-Signature: a=rsa-sha256; v=1; c=relaxed/relaxed; d=mg.codeaurora.org; q=dns/txt; s=smtp; t=1605566800; h=References: In-Reply-To: Message-Id: Date: Subject: Cc: To: From: Sender; bh=WOiKKq0MXSxYMZcw2q/1aRj0KjSFC6n5S675e9NXLdA=; b=asWsCBJYHmS+9x7lf528VazJDYUpL3Zn0j6/MQO8Pls3ZGeYuWMepe0MphDnCHGtjHVZIEGG 6svllv/F6YbTv2MEER3NYiOHByVsHQoSlQP5WqDptVk/IaYpmgrUCG8nhDaWnA5fPT4mTRB2 ELgbj3HxiS/eNLsKDmNm30Ds818= X-Mailgun-Sending-Ip: 104.130.96.5 X-Mailgun-Sid: WyJiZjI2MiIsICJuZXRkZXZAdmdlci5rZXJuZWwub3JnIiwgImJlOWU0YSJd Received: from smtp.codeaurora.org (ec2-35-166-182-171.us-west-2.compute.amazonaws.com [35.166.182.171]) by smtp-out-n04.prod.us-east-1.postgun.com with SMTP id 5fb30149309342b914f9f726 (version=TLS1.2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256); Mon, 16 Nov 2020 22:46:33 GMT Sender: hemantk=codeaurora.org@mg.codeaurora.org Received: by smtp.codeaurora.org (Postfix, from userid 1001) id 9DC7DC43461; Mon, 16 Nov 2020 22:46:32 +0000 (UTC) Received: from codeaurora.org (i-global254.qualcomm.com [199.106.103.254]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-SHA256 (128/128 bits)) (No client certificate requested) (Authenticated sender: hemantk) by smtp.codeaurora.org (Postfix) with ESMTPSA id 9F626C433C6; Mon, 16 Nov 2020 22:46:31 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 smtp.codeaurora.org 9F626C433C6 Authentication-Results: aws-us-west-2-caf-mail-1.web.codeaurora.org; dmarc=none (p=none dis=none) header.from=codeaurora.org Authentication-Results: aws-us-west-2-caf-mail-1.web.codeaurora.org; spf=fail smtp.mailfrom=hemantk@codeaurora.org From: Hemant Kumar To: manivannan.sadhasivam@linaro.org, gregkh@linuxfoundation.org Cc: linux-arm-msm@vger.kernel.org, linux-kernel@vger.kernel.org, jhugo@codeaurora.org, bbhatt@codeaurora.org, loic.poulain@linaro.org, netdev@vger.kernel.org, skhan@linuxfoundation.org, Hemant Kumar Subject: [PATCH v12 3/5] docs: Add documentation for userspace client interface Date: Mon, 16 Nov 2020 14:46:20 -0800 Message-Id: <1605566782-38013-4-git-send-email-hemantk@codeaurora.org> X-Mailer: git-send-email 2.7.4 In-Reply-To: <1605566782-38013-1-git-send-email-hemantk@codeaurora.org> References: <1605566782-38013-1-git-send-email-hemantk@codeaurora.org> Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org MHI userspace client driver is creating device file node for user application to perform file operations. File operations are handled by MHI core driver. Currently Loopback MHI channel is supported by this driver. Signed-off-by: Hemant Kumar --- Documentation/mhi/index.rst | 1 + Documentation/mhi/uci.rst | 86 +++++++++++++++++++++++++++++++++++++++++++++ 2 files changed, 87 insertions(+) create mode 100644 Documentation/mhi/uci.rst diff --git a/Documentation/mhi/index.rst b/Documentation/mhi/index.rst index 1d8dec3..c75a371 100644 --- a/Documentation/mhi/index.rst +++ b/Documentation/mhi/index.rst @@ -9,6 +9,7 @@ MHI mhi topology + uci .. only:: subproject and html diff --git a/Documentation/mhi/uci.rst b/Documentation/mhi/uci.rst new file mode 100644 index 0000000..ce8740e --- /dev/null +++ b/Documentation/mhi/uci.rst @@ -0,0 +1,86 @@ +.. SPDX-License-Identifier: GPL-2.0 + +================================= +Userspace Client Interface (UCI) +================================= + +UCI driver enables userspace clients to communicate to external MHI devices +like modem and WLAN. UCI driver probe creates standard character device file +nodes for userspace clients to perform open, read, write, poll and release file +operations. UCI device object represents UCI device file node which gets +instantiated as part of MHI UCI driver probe. UCI channel object represents +MHI uplink or downlink channel. + +Operations +========== + +open +---- + +Instantiates UCI channel object and starts MHI channels to move it to running +state. Inbound buffers are queued to downlink channel transfer ring. Every +subsequent open() increments UCI device reference count as well as UCI channel +reference count. + +read +---- + +When data transfer is completed on downlink channel, transfer ring element +buffer is copied to pending list. Reader is unblocked and data is copied to +userspace buffer. Transfer ring element buffer is queued back to downlink +channel transfer ring. + +write +----- + +Write buffer is queued to uplink channel transfer ring if ring is not full. Upon +uplink transfer completion buffer is freed. + +poll +---- + +Returns EPOLLIN | EPOLLRDNORM mask if pending list has buffers to be read by +userspace. Returns EPOLLOUT | EPOLLWRNORM mask if MHI uplink channel transfer +ring is not empty. Returns EPOLLERR when UCI driver is removed. + +release +------- + +Decrements UCI device reference count and UCI channel reference count upon last +release(). UCI channel clean up is performed. MHI channel moves to disable +state and inbound buffers are freed. + +Usage +===== + +Device file node is created with format:- + +/dev/mhi__ + +controller_name is the name of underlying bus used to transfer data. mhi_device +name is the name of the MHI channel being used by MHI client in userspace to +send or receive data using MHI protocol. + +There is a separate character device file node created for each channel +specified in MHI device id table. MHI channels are statically defined by MHI +specification. The list of supported channels is in the channel list variable +of mhi_device_id table in UCI driver. + +LOOPBACK Channel +---------------- + +Userspace MHI client using LOOPBACK channel opens device file node. As part of +open operation transfer ring elements are queued to transfer ring of LOOPBACK +channel 1 and channel doorbell is rung. When userspace MHI client performs write +operation on device node, data buffer gets queued as part of transfer ring +element to transfer ring of LOOPBACK channel 0. MHI Core driver rings the +channel doorbell for MHI device to move data over underlying bus. When userspace +MHI client driver performs read operation, same data gets looped back to MHI +host using LOOPBACK channel 1. LOOPBACK channel is used to verify data path +and data integrity between MHI Host and MHI device. + +Other Use Cases +--------------- + +Getting MHI device specific diagnostics information to userspace MHI diagnostic +client using DIAG channel 4 (Host to device) and 5 (Device to Host).