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=-2.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS,USER_AGENT_GIT 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 5DDD6C6786E for ; Fri, 26 Oct 2018 14:43:42 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 0217320868 for ; Fri, 26 Oct 2018 14:43:41 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 0217320868 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=bootlin.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727508AbeJZXU7 (ORCPT ); Fri, 26 Oct 2018 19:20:59 -0400 Received: from mail.bootlin.com ([62.4.15.54]:46161 "EHLO mail.bootlin.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726295AbeJZXU7 (ORCPT ); Fri, 26 Oct 2018 19:20:59 -0400 Received: by mail.bootlin.com (Postfix, from userid 110) id CE6A920970; Fri, 26 Oct 2018 16:43:35 +0200 (CEST) Received: from localhost.localdomain (aaubervilliers-681-1-12-210.w90-88.abo.wanadoo.fr [90.88.133.210]) by mail.bootlin.com (Postfix) with ESMTPSA id 1118D20794; Fri, 26 Oct 2018 16:43:35 +0200 (CEST) From: Boris Brezillon To: Wolfram Sang , linux-i2c@vger.kernel.org, Jonathan Corbet , linux-doc@vger.kernel.org, Greg Kroah-Hartman , Arnd Bergmann Cc: Przemyslaw Sroka , Arkadiusz Golec , Alan Douglas , Bartosz Folta , Damian Kos , Alicja Jurasik-Urbaniak , Cyprian Wronka , Suresh Punnoose , Rafal Ciepiela , Thomas Petazzoni , Nishanth Menon , Rob Herring , Pawel Moll , Mark Rutland , Ian Campbell , Kumar Gala , devicetree@vger.kernel.org, linux-kernel@vger.kernel.org, Vitor Soares , Geert Uytterhoeven , Linus Walleij , Xiang Lin , linux-gpio@vger.kernel.org, Sekhar Nori , Przemyslaw Gaj , Peter Rosin , Mike Shettel , Stephen Boyd , Boris Brezillon Subject: [PATCH v10 0/9] Add the I3C subsystem Date: Fri, 26 Oct 2018 16:43:24 +0200 Message-Id: <20181026144333.12276-1-boris.brezillon@bootlin.com> X-Mailer: git-send-email 2.17.1 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Greg, I think we've reached a point where we can eventually consider the I3C framework for inclusion in 4.20 (5.0?). A few more issues were reported on v9 and fixed in v10. I can't guarantee that the implementation is free of bugs but I still think it's worth merging it in v4.20: it's a new subsystem, so we don't risk regressions, and the only way we can detect other issues is by having other people experiment with this implementation. The only remaining concern raised by Arnd is the fact that both hosts and slaves share the same bus type and are differentiated thanks to their device_type, which IMHO is fine since this is what other subsystems do (plus I don't see other solutions to have both I3C devices and I3C buses represented under /sys/bus/i3c/). I'd really like to get this series merged in 4.20 so that other contributors can work on top of it to add 1/ new host drivers 2/ support for advanced features 3/ new device drivers So, unless you have strong reasons to reject this request, and, assuming I get Rob's ack soon enough, I plan to send a PR for this framework next week. Here is the usual description copy&pasted from the previous versions: This patch series is adding a new subsystem to support I3C devices. This is just adding support for basic features. Extra features will be added afterwards. There are a few design choices that are worth mentioning because they impact the way I3C device drivers can interact with their devices: - all functions used to send I3C/I2C frames must be called in non-atomic context. Mainly done this way to ease implementation, but this is still open to discussion. Please let me know if you think it's worth considering an asynchronous model here - the I3C bus and I3C master controller are now tightly coupled even though they're still allocated separately. There's now a 1:1 relationship between these objects, and the I3C master is no longer represented under the I3C bus object. Arnd, let me know if you had something different in mind, and I'll rework the implementation accordingly. - I2C backward compatibility has been designed to be transparent to I2C drivers and the I2C subsystem. The I3C master just registers an I2C adapter which creates a new I2C bus. I'd say that, from a representation PoV it's not ideal because what should appear as a single I3C bus exposing I3C and I2C devices here appears as 2 different busses connected to each other through the parenting (the I3C master is the parent of the I2C and I3C busses). On the other hand, I don't see a better solution if we want something that is not invasive. Missing features (will be added in separate patch series after initial support has been accepted/merged): - support for HDR modes (has been removed because of lack of real users) - no support for multi-master and the associated concepts (mastership handover, support for secondary masters, ...) - I2C devices can only be described using DT because this is the only use case I have. However, the framework can easily be extended with ACPI and board info support - I3C slave framework. This has been completely omitted, but shouldn't have a huge impact on the I3C framework because I3C slaves don't see the whole bus, it's only about handling master requests and generating IBIs. Some of the struct, constant and enum definitions could be shared, but most of the I3C slave framework logic will be different Note that this patchset is available on the linux-i3c repo[1]. Main change between v8 and v9: - The DT bindings have been simplified to get rid of the I3C/I3C_DEV() macros Main change between v7 and v8: - The bus object is now embedded in the master_controller object (as suggested by Arnd) Main changes between v6 and v7: - I3C bus/master representations have been reworked to match what other subsystems are doing (master implicitly represented by the bus object) - I3C dev registration has been fixed - I3C bus mode selection has been fixed - Calls to readsl/writesl() in the Cadence I3C master driver have been fixed Main changes between v5 and v6: - Introduce {i3c,i2c}_dev_desc structures to better match how I3C master controllers (reservation of one HW slot for each device attached to the bus). With this solution, the resource migration that happens when a device lose its dynamic address and is re-assigned a different address is simplified on the driver side, because most of it is now handled in the core (reserve a new dev slot, reserve IBI resources and free all resources attached to the old slot) - Add I3C error codes (M0 to M2) so that the core and device drivers can have fine grained information on what caused an EIO error. Only minor things happened between v3 and v5 (you can go check the changelog in each patch for more details). Main changes between v2 and v3 are: - Reworked the DT bindings as suggested by Rob - Reworked the bus initialization step as suggested by Vitor - Added a driver for an I3C GPIO expander Main changes between the initial RFC and this v2 are: - Add a generic infrastructure to support IBIs. It's worth mentioning that I tried exposing IBIs as a regular IRQs, but after several attempts and a discussion with Mark Zyngier, it appeared that it was not really fitting in the Linux IRQ model (the fact that you have payload attached to IBIs, the fact that most of the time an IBI will generate a transfer on the bus which has to be done in an atomic context, ...) The counterpart of this decision is the latency induced by the workqueue approach, but since I don't have real use cases, I don't know if this can be a problem or not. - Add helpers to support Hot Join - Add support for IBIs and Hot Join in Cadence I3C master driver - Address several issues in how I was using the device model Thanks, Boris [1]https://git.kernel.org/pub/scm/linux/kernel/git/i3c/linux.git/log/?h=i3c/next *** BLURB HERE *** Boris Brezillon (9): i3c: Add core I3C infrastructure docs: driver-api: Add I3C documentation i3c: Add sysfs ABI spec dt-bindings: i3c: Document core bindings MAINTAINERS: Add myself as the I3C subsystem maintainer i3c: master: Add driver for Cadence IP dt-bindings: i3c: Document Cadence I3C master bindings gpio: Add a driver for Cadence I3C GPIO expander dt-bindings: gpio: Add bindings for Cadence I3C gpio expander Documentation/ABI/testing/sysfs-bus-i3c | 146 + .../bindings/gpio/gpio-cdns-i3c.txt | 39 + .../bindings/i3c/cdns,i3c-master.txt | 44 + Documentation/devicetree/bindings/i3c/i3c.txt | 139 + .../driver-api/i3c/device-driver-api.rst | 9 + Documentation/driver-api/i3c/index.rst | 11 + .../driver-api/i3c/master-driver-api.rst | 10 + Documentation/driver-api/i3c/protocol.rst | 203 ++ Documentation/driver-api/index.rst | 1 + MAINTAINERS | 12 + drivers/Kconfig | 2 + drivers/Makefile | 2 +- drivers/gpio/Kconfig | 11 + drivers/gpio/Makefile | 1 + drivers/gpio/gpio-cdns-i3c.c | 411 +++ drivers/i3c/Kconfig | 24 + drivers/i3c/Makefile | 4 + drivers/i3c/device.c | 233 ++ drivers/i3c/internals.h | 26 + drivers/i3c/master.c | 2661 +++++++++++++++++ drivers/i3c/master/Kconfig | 6 + drivers/i3c/master/Makefile | 1 + drivers/i3c/master/i3c-master-cdns.c | 1671 +++++++++++ include/linux/i3c/ccc.h | 385 +++ include/linux/i3c/device.h | 331 ++ include/linux/i3c/master.h | 648 ++++ include/linux/mod_devicetable.h | 17 + 27 files changed, 7047 insertions(+), 1 deletion(-) create mode 100644 Documentation/ABI/testing/sysfs-bus-i3c create mode 100644 Documentation/devicetree/bindings/gpio/gpio-cdns-i3c.txt create mode 100644 Documentation/devicetree/bindings/i3c/cdns,i3c-master.txt create mode 100644 Documentation/devicetree/bindings/i3c/i3c.txt create mode 100644 Documentation/driver-api/i3c/device-driver-api.rst create mode 100644 Documentation/driver-api/i3c/index.rst create mode 100644 Documentation/driver-api/i3c/master-driver-api.rst create mode 100644 Documentation/driver-api/i3c/protocol.rst create mode 100644 drivers/gpio/gpio-cdns-i3c.c create mode 100644 drivers/i3c/Kconfig create mode 100644 drivers/i3c/Makefile create mode 100644 drivers/i3c/device.c create mode 100644 drivers/i3c/internals.h create mode 100644 drivers/i3c/master.c create mode 100644 drivers/i3c/master/Kconfig create mode 100644 drivers/i3c/master/Makefile create mode 100644 drivers/i3c/master/i3c-master-cdns.c create mode 100644 include/linux/i3c/ccc.h create mode 100644 include/linux/i3c/device.h create mode 100644 include/linux/i3c/master.h -- 2.17.1