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 X-Spam-Level: X-Spam-Status: No, score=-7.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,MENTIONS_GIT_HOSTING,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED, USER_AGENT_SANE_2 autolearn=ham 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 7F12DC34022 for ; Wed, 19 Feb 2020 08:17:06 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 5A0B62176D for ; Wed, 19 Feb 2020 08:17:06 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726717AbgBSIRF (ORCPT ); Wed, 19 Feb 2020 03:17:05 -0500 Received: from bhuna.collabora.co.uk ([46.235.227.227]:60918 "EHLO bhuna.collabora.co.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726156AbgBSIRE (ORCPT ); Wed, 19 Feb 2020 03:17:04 -0500 Received: from localhost (unknown [IPv6:2a01:e0a:2c:6930:5cf4:84a1:2763:fe0d]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) (Authenticated sender: bbrezillon) by bhuna.collabora.co.uk (Postfix) with ESMTPSA id 1EB82292F60; Wed, 19 Feb 2020 08:17:02 +0000 (GMT) Date: Wed, 19 Feb 2020 09:16:58 +0100 From: Boris Brezillon To: Vitor Soares Cc: "bbrezillon@kernel.org" , Joao Pinto , Jose Abreu , "gregkh@linuxfoundation.org" , "wsa@the-dreams.de" , "arnd@arndb.de" , "broonie@kernel.org" , "corbet@lwn.net" , "linux-kernel@vger.kernel.org" , "linux-i3c@lists.infradead.org" Subject: Re: [PATCH v3 0/5] Introduce i3c device userspace interface Message-ID: <20200219091658.7506e7bd@collabora.com> In-Reply-To: References: Organization: Collabora X-Mailer: Claws Mail 3.17.4 (GTK+ 2.24.32; x86_64-redhat-linux-gnu) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, 19 Feb 2020 00:39:31 +0000 Vitor Soares wrote: > Hi Boris, > > From: Vitor Soares > Date: Wed, Feb 19, 2020 at 00:20:38 > > > For today there is no way to use i3c devices from user space and > > the introduction of such API will help developers during the i3c device > > or i3c host controllers development. > > > > The i3cdev module is highly based on i2c-dev and yet I tried to address > > the concerns raised in [1]. > > > > NOTES: > > - The i3cdev dynamically request an unused major number. > > > > - The i3c devices are dynamically exposed/removed from dev/ folder based > > on if they have a device driver bound to it. > > > > - For now, the module exposes i3c devices without device driver on > > dev/bus/i3c/- > > > > - As in the i2c subsystem, here it is exposed the i3c_priv_xfer to > > userspace. I tried to use a dedicated structure as in spidev but I don't > > see any obvious advantage. > > > > - Since the i3c API only exposes i3c_priv_xfer to devices, for now, the > > module just makes use of one ioctl(). This can change in the future with > > the introduction hdr commands or by the need of exposing some CCC > > commands to the device API (private contract between master-slave). > > Regarding the i3c device info, some information is already available > > through sysfs. We can add more device attributes to expose more > > information or add a dedicated ioctl() request for that purpose or both. > > > > - Similar to i2c, I have also created a tool that you can find in [2] > > for testing purposes. If you have some time available I would appreciate > > your feedback about it as well. > > > > [1] https://lkml.org/lkml/2018/11/15/853 > > [2] https://github.com/vitor-soares-snps/i3c-tools.git > > > > Changes in v3: > > Use the xfer_lock to prevent device detach during ioctl call > > Expose i3cdev under /dev/bus/i3c/ folder like usb does > > Change NOTIFY_BOUND to NOTIFY_BIND, this allows the device detach occur > > before driver->probe call > > Avoid use of IS_ERR_OR_NULL > > Use u64_to_user_ptr instead of (void __user *)(uintptr_t) cast > > Allocate k_xfer and data_ptrs at once and eliminate double allocation > > check > > Pass i3cdev to dev->driver_data > > Make all minors available > > Add API documentation > > > > Changes in v2: > > Use IDR api for minor numbering > > Modify ioctl struct > > Fix SPDX license > > > > Vitor Soares (5): > > i3c: master: export i3c_masterdev_type > > i3c: master: export i3c_bus_type symbol > > i3c: master: add i3c_for_each_dev helper > > i3c: add i3cdev module to expose i3c dev in /dev > > userspace-api: add i3cdev documentation > > > > Documentation/userspace-api/i3c/i3cdev.rst | 116 ++++++++ > > drivers/i3c/Kconfig | 15 + > > drivers/i3c/Makefile | 1 + > > drivers/i3c/i3cdev.c | 429 +++++++++++++++++++++++++++++ > > drivers/i3c/internals.h | 2 + > > drivers/i3c/master.c | 16 +- > > include/uapi/linux/i3c/i3cdev.h | 38 +++ > > 7 files changed, 616 insertions(+), 1 deletion(-) > > create mode 100644 Documentation/userspace-api/i3c/i3cdev.rst > > create mode 100644 drivers/i3c/i3cdev.c > > create mode 100644 include/uapi/linux/i3c/i3cdev.h > > > > -- > > 2.7.4 > > I want to make you know that none of your previous comments was ignored > and I would like to start the discussion from this point. Sure, np. I'll probably wait for a v4 exploring the option I proposed then.