From patchwork Wed Nov 4 23:23:54 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Saravana Kannan X-Patchwork-Id: 11882335 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=-20.4 required=3.0 tests=BAYES_00,DKIMWL_WL_MED, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, USER_AGENT_GIT,USER_IN_DEF_DKIM_WL 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 78865C4741F for ; Wed, 4 Nov 2020 23:25:07 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 244C320786 for ; Wed, 4 Nov 2020 23:25:07 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="DVZtwNlz" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1732684AbgKDXZG (ORCPT ); Wed, 4 Nov 2020 18:25:06 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:45048 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1733122AbgKDXYp (ORCPT ); Wed, 4 Nov 2020 18:24:45 -0500 Received: from mail-yb1-xb4a.google.com (mail-yb1-xb4a.google.com [IPv6:2607:f8b0:4864:20::b4a]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 60D1DC0613CF for ; Wed, 4 Nov 2020 15:24:43 -0800 (PST) Received: by mail-yb1-xb4a.google.com with SMTP id b25so424365ybj.2 for ; Wed, 04 Nov 2020 15:24:43 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20161025; h=sender:date:in-reply-to:message-id:mime-version:references:subject :from:to:cc; bh=UFRlchaIccsk0JGD42LufUh5WHL/iRO0t5U2dOMSWQI=; b=DVZtwNlzUvhu1bT2ylduD17IaOiKiLS3Xrt/pqRBfM9JAG32+swkygL69PmMRvoWhD mj/Jpu82kklLO2wzJNnP0ZF/yF5jbqPKJkBHmeyJ74/LJDzu32tel3FiTYqhDMEt5SrI 0ubtl2yP/UPmzJtTdhZ/puSkDPJYWSZtGZ02VQobv5MVspZhus+fqBb3M0XrOe8vXB9D 90BykzQ1Y4VIrqlpT2R1/jNsyJ/fxiN4RpKrkTgO0hSeZpr1hMTlJEICVdTvq9rqJjEF aNxPctEVyYV7ognSHXbPb7puCiS4kRL9rPHzVgBbJa8t42aBS0UmoIgsQR6SU+HFLA5a j/YA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:sender:date:in-reply-to:message-id:mime-version :references:subject:from:to:cc; bh=UFRlchaIccsk0JGD42LufUh5WHL/iRO0t5U2dOMSWQI=; b=MnIG0AggDyD9J8ZV2EVdWPXkQ5FOUgbbxnPKfl2tQJp+dPGSlP3DnIEFEH+vb86ubo 2Kiqo9ZEekWKbrUmGf1B4whAR8u+TFFsJHCYmoPn1Y8vokwUj06343frS0kyb3YBIcGY oG/xwRwqct+ZezUol6BRKBMHQyUDQ7V2xjgbblc5gkBuuKF/1ou3FFDvhT9QKtnW6tt1 e26PtSPgx+99owSiIU4lPnUmVPYPDHOIPGa9p6x8WuvfdNCLKpzOHw0Kvvmf0880g22I 8X2dVHyEK4WPxcdNt+FNgU438x73UA8s8He1BfMpXrgWbgjywp2u9Xbuw1z3sCvKw9Er glbw== X-Gm-Message-State: AOAM5324o4+VykAjI31ViLhsufEDtOzwuL2ui5gem/l0Il96wX4hpQmE 0r+ELxStxLxhUnQAZpD1XLAWhOWqBrfbktA= X-Google-Smtp-Source: ABdhPJyFTyTz9U39nyonyGauPk616+s3tOk5O4R2ocwWkkWD1/UZ5J5Wz1mvahqfCGL8MHVgQgmjjxoLzce+IEk= Sender: "saravanak via sendgmr" X-Received: from saravanak.san.corp.google.com ([2620:15c:2d:3:7220:84ff:fe09:fedc]) (user=saravanak job=sendgmr) by 2002:a25:afc1:: with SMTP id d1mr268166ybj.27.1604532282595; Wed, 04 Nov 2020 15:24:42 -0800 (PST) Date: Wed, 4 Nov 2020 15:23:54 -0800 In-Reply-To: <20201104232356.4038506-1-saravanak@google.com> Message-Id: <20201104232356.4038506-18-saravanak@google.com> Mime-Version: 1.0 References: <20201104232356.4038506-1-saravanak@google.com> X-Mailer: git-send-email 2.29.1.341.ge80a0c044ae-goog Subject: [PATCH v1 17/18] driver core: Add helper functions to convert fwnode links to device links From: Saravana Kannan To: "Rafael J. Wysocki" , "Rafael J. Wysocki" , Len Brown , Greg Kroah-Hartman , Ard Biesheuvel , Rob Herring , Frank Rowand , Marc Zyngier , Thomas Gleixner Cc: Saravana Kannan , Tomi Valkeinen , Laurent Pinchart , Grygorii Strashko , kernel-team@android.com, linux-acpi@vger.kernel.org, linux-kernel@vger.kernel.org, linux-efi@vger.kernel.org, devicetree@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-acpi@vger.kernel.org Add helper functions __fw_devlink_link_to_consumers() and __fw_devlink_link_to_suppliers() that convert fwnode links to device links. __fw_devlink_link_to_consumers() is for creating: - Device links between a newly added device and all its consumer devices that have been added to driver core. - Proxy SYNC_STATE_ONLY device links between the newly added device and the parent devices of all its consumers that have not been added to driver core yet. __fw_devlink_link_to_suppliers() is for creating: - Device links between a newly added device and all its supplier devices - Proxy SYNC_STATE_ONLY device links between the newly added device and all the supplier devices of its child device nodes. Signed-off-by: Saravana Kannan --- drivers/base/core.c | 228 ++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 228 insertions(+) diff --git a/drivers/base/core.c b/drivers/base/core.c index d51dd564add1..0c87ff949d81 100644 --- a/drivers/base/core.c +++ b/drivers/base/core.c @@ -1585,6 +1585,234 @@ static struct device *fwnode_get_next_parent_dev(struct fwnode_handle *fwnode) return dev; } +/** + * fw_devlink_create_devlink - Create a device link from a consumer to fwnode + * @con - Consumer device for the device link + * @sup - fwnode handle of supplier + * + * This function will try to create a device link between the consumer and the + * supplier devices. + * + * The supplier has to be provided as a fwnode because incorrect cycles in + * fwnode links can sometimes cause the supplier device to never be created. + * This function detects such cases and returns an error if a device link being + * created in invalid. + * + * Returns, + * 0 on successfully creating a device link + * -EINVAL if the device link being attempted is invalid + * -EAGAIN if the device link needs to be attempted again in the future + */ +static int fw_devlink_create_devlink(struct device *con, + struct fwnode_handle *sup, u32 flags) +{ + struct device *sup_dev, *sup_par_dev; + int ret = 0; + + sup_dev = get_dev_from_fwnode(sup); + /* + * If we can't find the supplier device from its fwnode, it might be + * due to a cyclic dependcy between fwnodes. Some of these cycles can + * be broken by applying logic. Check for these types of cycles and + * break them so that devices in the cycle probe properly. + */ + if (!sup_dev) { + /* + * DL_FLAG_SYNC_STATE_ONLY doesn't block probing and supports + * cycles. So cycle detection isn't necessary and shouldn't be + * done. + */ + if (flags & DL_FLAG_SYNC_STATE_ONLY) + return -EAGAIN; + + sup_par_dev = fwnode_get_next_parent_dev(sup); + + /* + * If the supplier's parent is dependent on the consumer, then + * the consumer-supplier dependency is a false dependency. So, + * treat it as an invalid link. + */ + if (sup_par_dev && device_is_dependent(con, sup_par_dev)) { + dev_dbg(con, "Not linking to %pfwP - False link\n", + sup); + ret = -EINVAL; + } else { + /* + * Can't check for cycles or no cycles. So let's try + * again later. + */ + ret = -EAGAIN; + } + + put_device(sup_par_dev); + return ret; + } + + /* + * If we get this far and fail, this is due to cycles in device links. + * Just give up on this link and treat it as invalid. + */ + if (!device_link_add(con, sup_dev, flags)) + ret = -EINVAL; + put_device(sup_dev); + + return ret; +} + +/** + * __fw_devlink_link_to_consumers - Create device links to consumers of a device + * @dev - Device that needs to be linked to its consumers + * + * This function looks at all the consumer fwnodes of @dev and creates device + * links between the consumer device and @dev (supplier). + * + * If the consumer device has not been added yet, then this function creates a + * SYNC_STATE_ONLY link between @dev (supplier) and the closest ancestor device + * of the consumer fwnode. This is necessary to make sure @dev doesn't get a + * sync_state() callback before the real consumer device gets to be added and + * then probed. + * + * Once device links are created from the real consumer to @dev (supplier), the + * fwnode links are deleted. + */ +static void __fw_devlink_link_to_consumers(struct device *dev) +{ + struct fwnode_handle *fwnode = dev->fwnode; + struct fwnode_link *link, *tmp; + + list_for_each_entry_safe(link, tmp, &fwnode->consumers, s_hook) { + u32 dl_flags = fw_devlink_get_flags(); + struct device *con_dev; + bool own_link = true; + int ret; + + con_dev = get_dev_from_fwnode(link->consumer); + /* + * If consumer device is not available yet, make a "proxy" + * SYNC_STATE_ONLY link from the consumer's parent device to + * the supplier device. This is necessary to make sure the + * supplier doesn't get a sync_state() callback before the real + * consumer can create a device link to the supplier. + * + * This proxy link step is needed to handle the case where the + * consumer's parent device is added before the supplier. + */ + if (!con_dev) { + con_dev = fwnode_get_next_parent_dev(link->consumer); + /* + * However, if the consumer's parent device is also the + * parent of the supplier, don't create a + * consumer-supplier link from the parent to its child + * device. Such a dependency is impossible. + */ + if (con_dev && + fwnode_is_ancestor_of(con_dev->fwnode, fwnode)) { + put_device(con_dev); + con_dev = NULL; + } else { + own_link = false; + dl_flags = DL_FLAG_SYNC_STATE_ONLY; + } + } + + if (!con_dev) + continue; + + ret = fw_devlink_create_devlink(con_dev, fwnode, dl_flags); + put_device(con_dev); + if (!own_link || ret == -EAGAIN) + continue; + + list_del(&link->s_hook); + list_del(&link->c_hook); + kfree(link); + } +} + +/** + * __fw_devlink_link_to_suppliers - Create device links to suppliers of a device + * @dev - The consumer device that needs to be linked to its suppliers + * @fwnode - Root of the fwnode tree that is used to create device links + * + * This function looks at all the supplier fwnodes of fwnode tree rooted at + * @fwnode and creates device links between @dev (consumer) and all the + * supplier devices of the entire fwnode tree at @fwnode. See + * fw_devlink_create_devlink() for more details. + * + * The function creates normal (non-SYNC_STATE_ONLY) device links between @dev + * and the real suppliers of @dev. Once these device links are created, the + * fwnode links are deleted. When such device links are successfully created, + * this function is called recursively on those supplier devices. This is + * needed to detect and break some invalid cycles in fwnode links. + * + * In addition, it also looks at all the suppliers of the entire fwnode tree + * because some of the child devices of @dev that have not been added yet + * (because @dev hasn't probed) might already have their suppliers added to + * driver core. So, this function creates SYNC_STATE_ONLY device links between + * @dev (consumer) and these suppliers to make sure they don't execute their + * sync_state() callbacks before these child devices have a chance to create + * their device links. The fwnode links that correspond to the child devices + * aren't delete because they are needed later to create the device links + * between the real consumer and supplier devices. + */ +static void __fw_devlink_link_to_suppliers(struct device *dev, + struct fwnode_handle *fwnode) +{ + bool own_link = (dev->fwnode == fwnode); + struct fwnode_link *link, *tmp; + struct fwnode_handle *child = NULL; + u32 dl_flags; + + if (own_link) + dl_flags = fw_devlink_get_flags(); + else + dl_flags = DL_FLAG_SYNC_STATE_ONLY; + + list_for_each_entry_safe(link, tmp, &fwnode->suppliers, c_hook) { + int ret; + struct device *sup_dev; + struct fwnode_handle *sup = link->supplier; + + ret = fw_devlink_create_devlink(dev, sup, dl_flags); + if (!own_link || ret == -EAGAIN) + continue; + + list_del(&link->s_hook); + list_del(&link->c_hook); + kfree(link); + + /* If no device link was created, nothing more to do. */ + if (ret) + continue; + + /* + * If a device link was successfully created to a supplier, we + * now need to try and link the supplier to all its suppliers. + * + * This is needed to detect and delete false dependencies in + * fwnode links that haven't been converted to a device link + * yet. See comments in fw_devlink_create_devlink() for more + * details on the false dependency. + * + * Without deleting these false dependencies, some devices will + * never probe because they'll keep waiting for their false + * dependency fwnode links to be converted to device links. + */ + sup_dev = get_dev_from_fwnode(sup); + __fw_devlink_link_to_suppliers(sup_dev, sup_dev->fwnode); + put_device(sup_dev); + } + + /* + * Make "proxy" SYNC_STATE_ONLY device links to represent the needs of + * all the descendants. This proxy link step is needed to handle the + * case where the supplier is added before the consumer's parent device + * (@dev). + */ + while ((child = fwnode_get_next_available_child_node(fwnode, child))) + __fw_devlink_link_to_suppliers(dev, child); +} + static void fw_devlink_link_device(struct device *dev) { int fw_ret;