From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932997AbcFQGaJ (ORCPT ); Fri, 17 Jun 2016 02:30:09 -0400 Received: from mailout2.w1.samsung.com ([210.118.77.12]:28443 "EHLO mailout2.w1.samsung.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755015AbcFQG1O (ORCPT ); Fri, 17 Jun 2016 02:27:14 -0400 X-AuditID: cbfec7f4-f796c6d000001486-bb-5763983f7d32 From: Marek Szyprowski To: linux-pm@vger.kernel.org, linux-kernel@vger.kernel.org, iommu@lists.linux-foundation.org, linux-samsung-soc@vger.kernel.org, linux-arm-kernel@lists.infradead.org Cc: Marek Szyprowski , Joerg Roedel , Inki Dae , Kukjin Kim , Krzysztof Kozlowski , Bartlomiej Zolnierkiewicz , "Rafael J. Wysocki" , Ulf Hansson , Mark Brown , Greg Kroah-Hartman , "Rafael J. Wysocki" Subject: [PATCH v2 02/10] driver core: Functional dependencies tracking support Date: Fri, 17 Jun 2016 08:26:52 +0200 Message-id: <1466144820-6286-3-git-send-email-m.szyprowski@samsung.com> X-Mailer: git-send-email 1.9.1 In-reply-to: <1466144820-6286-1-git-send-email-m.szyprowski@samsung.com> References: <1466144820-6286-1-git-send-email-m.szyprowski@samsung.com> X-Brightmail-Tracker: H4sIAAAAAAAAA+NgFrrJLMWRmVeSWpSXmKPExsVy+t/xa7r2M5LDDTb0CllsnLGe1WLqwyds Fs2L17NZTLo/gcViwX5ri87ZG9gtXr8wtOh//JrZYtPja6wWl3fNYbP43HuE0WLG+X1MFmuP 3GW3eLziLbvFmdOXWC2Orw13EPB4cnAek8fiPS+ZPDat6mTzuHNtD5vH/rlr2D02L6n3mHxj OaPHlqvtLB59W1YxenzeJBfAFcVlk5Kak1mWWqRvl8CV8XDeQvaC3TsYKyYs3MTWwHhlGmMX IweHhICJxI7FFl2MnECmmMSFe+vZuhi5OIQEljJKTF09lRnCaWKS2H96EytIFZuAoUTX2y6w KhGBlYwS2/bsA6tiFrjKLDFnz04WkCphAX+JjZuuM4HYLAKqEvMnHGQEsXkF3CVmr9vPCrFP TuLksclgNqeAh8SLWz/AeoWAanYdPsU8gZF3ASPDKkbR1NLkguKk9FxDveLE3OLSvHS95Pzc TYyQAP+yg3HxMatDjAIcjEo8vCtEk8OFWBPLiitzDzFKcDArifBqTgcK8aYkVlalFuXHF5Xm pBYfYpTmYFES5527632IkEB6YklqdmpqQWoRTJaJg1OqgbFIoGPdLCu/ePvNKS7SNmu2qhgs fLQ51be7ePv1/yv/Tf1fyeZx4k2iH8P6TGmuK7c8l6svlRHK5ju6vim2u+ZHms60Xo97l24n yBelTLHTqFS97v439rzM5iWWbIK+y4+pKeSFnTp+3lXGk9XI3v133oTFWcvnrjhk+t4lcME/ Bsbs/Rbp4kosxRmJhlrMRcWJANemVzpsAgAA Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: "Rafael J. Wysocki" Currently, there is a problem with handling cases where functional dependencies between devices are involved. What I mean by a "functional dependency" is when the driver of device B needs both device A and its driver to be present and functional to be able to work. This implies that the driver of A needs to be working for B to be probed successfully and it cannot be unbound from the device before the B's driver. This also has certain consequences for power management of these devices (suspend/resume and runtime PM ordering). Add support for representing those functional dependencies between devices to allow the driver core to track them and act on them in certain cases where they matter. The argument for doing that in the driver core is that there are quite a few distinct use cases related to that, they are relatively hard to get right in a driver (if one wants to address all of them properly) and it only gets worse if multiplied by the number of drivers potentially needing to do it. Morever, at least one case (asynchronous system suspend/resume) cannot be handled in a single driver at all, because it requires the driver of A to wait for B to suspend (during system suspend) and the driver of B to wait for A to resume (during system resume). To that end, represent links between devices (or more precisely between device+driver combos) as a struct devlink object containing pointers to the devices in question, a list node for each of them, status information, flags, a lock and an RCU head for synchronization. Also add two new list heads, supplier_links and consumer_links, to struct device to represent the lists of links to the devices that depend on the given one (consumers) and to the devices depended on by it (suppliers), respectively. The entire data structure consisting of all of the lists of link objects for all devices is protected by SRCU (for list walking) and a by mutex (for link object addition/removal). In addition to that, each link object has an internal status field whose value reflects what's happening to the devices pointed to by the link. That status field is protected by an internal spinlock. New links are added by calling device_link_add() which may happen either before the consumer device is probed or when probing it, in which case the caller needs to ensure that the driver of the supplier device is present and functional and the DEVICE_LINK_PROBE_TIME flag should be passed to device_link_add() to reflect that. Link objects are deleted either explicitly, by calling device_link_del() on the link object in question, or automatically, when the consumer device is unbound from its driver or when one of the target devices is deleted, depending on the link type. There are two types of link objects, persistent and non-persistent. The difference between them is that the persistent links stay around until one of the target devices is deleted, which the non-persistent ones are deleted when the consumer driver is unbound from its device (ie. they are assumed to be valid only as long as the consumer device has a driver bound to it). The DEVICE_LINK_PERSISTENT flag has to be passed to device_link_add() so as to create a persistent link. One of the actions carried out by device_link_add() is to reorder the lists used for device shutdown and system suspend/resume to put the consumer device along with all of its children and all of its consumers (and so on, recursively) to the ends of those list in order to ensure the right ordering between the all of the supplier and consumer devices. Signed-off-by: Rafael J. Wysocki Signed-off-by: Marek Szyprowski --- drivers/base/base.h | 11 ++ drivers/base/core.c | 386 +++++++++++++++++++++++++++++++++++++++++++++++++ drivers/base/dd.c | 42 +++++- include/linux/device.h | 36 +++++ 4 files changed, 470 insertions(+), 5 deletions(-) diff --git a/drivers/base/base.h b/drivers/base/base.h index e05db388bd1c..cccb1d211541 100644 --- a/drivers/base/base.h +++ b/drivers/base/base.h @@ -107,6 +107,9 @@ extern void bus_remove_device(struct device *dev); extern int bus_add_driver(struct device_driver *drv); extern void bus_remove_driver(struct device_driver *drv); +extern void device_release_driver_internal(struct device *dev, + struct device_driver *drv, + struct device *parent); extern void driver_detach(struct device_driver *drv); extern int driver_probe_device(struct device_driver *drv, struct device *dev); @@ -152,3 +155,11 @@ extern int devtmpfs_init(void); #else static inline int devtmpfs_init(void) { return 0; } #endif + +/* Device links */ +extern int device_links_check_suppliers(struct device *dev); +extern void device_links_driver_bound(struct device *dev); +extern void device_links_driver_gone(struct device *dev); +extern void device_links_no_driver(struct device *dev); +extern bool device_links_busy(struct device *dev); +extern void device_links_unbind_consumers(struct device *dev); diff --git a/drivers/base/core.c b/drivers/base/core.c index 0a8bdade53f2..416341df3268 100644 --- a/drivers/base/core.c +++ b/drivers/base/core.c @@ -44,6 +44,367 @@ static int __init sysfs_deprecated_setup(char *arg) early_param("sysfs.deprecated", sysfs_deprecated_setup); #endif +/* Device links support. */ + +DEFINE_STATIC_SRCU(device_links_srcu); +static DEFINE_MUTEX(device_links_lock); + +static int device_reorder_to_tail(struct device *dev, void *not_used) +{ + struct devlink *link; + + devices_kset_move_last(dev); + device_pm_move_last(dev); + device_for_each_child(dev, NULL, device_reorder_to_tail); + list_for_each_entry(link, &dev->consumer_links, c_node) + device_reorder_to_tail(link->consumer, NULL); + + return 0; +} + +/** + * device_link_add - Create a link between two devices. + * @consumer: Consumer end of the link. + * @supplier: Supplier end of the link. + * @flags: Link flags. + * + * At least one of the flags must be set. If DEVICE_LINK_PROBE_TIME is set, the + * caller is expected to know that (a) the supplier device is present and active + * (ie. its driver is functional) and (b) the consumer device is probing at the + * moment and therefore the initial state of the link will be "consumer probe" + * in that case. If DEVICE_LINK_PROBE_TIME is not set, DEVICE_LINK_PERSISTENT + * must be set (meaning that the link will not go away when the consumer driver + * goes away). + * + * A side effect of the link creation is re-ordering of dpm_list and the + * devices_kset list by moving the consumer device and all devices depending + * on it to the ends of those lists. + */ +struct devlink *device_link_add(struct device *consumer, + struct device *supplier, u32 flags) +{ + struct devlink *link; + + if (!consumer || !supplier || !flags) + return NULL; + + mutex_lock(&device_links_lock); + + list_for_each_entry(link, &supplier->supplier_links, s_node) + if (link->consumer == consumer) + goto out; + + link = kmalloc(sizeof(*link), GFP_KERNEL); + if (!link) + goto out; + + get_device(supplier); + link->supplier = supplier; + INIT_LIST_HEAD(&link->s_node); + get_device(consumer); + link->consumer = consumer; + INIT_LIST_HEAD(&link->c_node); + link->flags = flags; + link->status = (flags & DEVICE_LINK_PROBE_TIME) ? + DEVICE_LINK_CONSUMER_PROBE : DEVICE_LINK_DORMANT; + spin_lock_init(&link->lock); + + /* + * Move the consumer and all of the devices depending on it to the end + * of dpm_list and the devices_kset list. + * + * We have to hold dpm_list locked throughout all that or else we may + * end up suspending with a wrong ordering of it. + */ + device_pm_lock(); + device_reorder_to_tail(consumer, NULL); + device_pm_unlock(); + + list_add_tail_rcu(&link->s_node, &supplier->supplier_links); + list_add_tail_rcu(&link->c_node, &consumer->consumer_links); + + dev_info(consumer, "Linked as a consumer to %s\n", dev_name(supplier)); + + out: + mutex_unlock(&device_links_lock); + return link; +} +EXPORT_SYMBOL_GPL(device_link_add); + +static void __devlink_free_srcu(struct rcu_head *rhead) +{ + struct devlink *link; + + link = container_of(rhead, struct devlink, rcu_head); + put_device(link->consumer); + put_device(link->supplier); + kfree(link); +} + +static void devlink_del(struct devlink *link) +{ + dev_info(link->consumer, "Dropping the link to %s\n", + dev_name(link->supplier)); + + list_del_rcu(&link->s_node); + list_del_rcu(&link->c_node); + call_srcu(&device_links_srcu, &link->rcu_head, __devlink_free_srcu); +} + +/** + * device_link_del - Delete a link between two devices. + * @link: Device link to delete. + */ +void device_link_del(struct devlink *link) +{ + mutex_lock(&device_links_lock); + devlink_del(link); + mutex_unlock(&device_links_lock); +} +EXPORT_SYMBOL_GPL(device_link_del); + +static int device_links_read_lock(void) +{ + return srcu_read_lock(&device_links_srcu); +} + +static void device_links_read_unlock(int idx) +{ + return srcu_read_unlock(&device_links_srcu, idx); +} + +static void device_links_missing_supplier(struct device *dev) +{ + struct devlink *link; + + list_for_each_entry_rcu(link, &dev->consumer_links, c_node) { + spin_lock(&link->lock); + + if (link->status == DEVICE_LINK_CONSUMER_PROBE) + link->status = DEVICE_LINK_AVAILABLE; + + spin_unlock(&link->lock); + } +} + +/** + * device_links_check_suppliers - Check supplier devices for this one. + * @dev: Consumer device. + * + * Check links from this device to any suppliers. Walk the list of the device's + * consumer links and see if all of the suppliers are available. If not, simply + * return -EPROBE_DEFER. + * + * Walk the list under SRCU and check each link's status field under its lock. + * + * We need to guarantee that the supplier will not go away after the check has + * been positive here. It only can go away in __device_release_driver() and + * that function checks the device's links to consumers. This means we need to + * mark the link as "consumer probe in progress" to make the supplier removal + * wait for us to complete (or bad things may happen). + */ +int device_links_check_suppliers(struct device *dev) +{ + struct devlink *link; + int idx, ret = 0; + + idx = device_links_read_lock(); + + list_for_each_entry_rcu(link, &dev->consumer_links, c_node) { + spin_lock(&link->lock); + if (link->status != DEVICE_LINK_AVAILABLE) { + spin_unlock(&link->lock); + device_links_missing_supplier(dev); + ret = -EPROBE_DEFER; + break; + } + link->status = DEVICE_LINK_CONSUMER_PROBE; + spin_unlock(&link->lock); + } + + device_links_read_unlock(idx); + return ret; +} + +/** + * device_links_driver_bound - Update device links after probing its driver. + * @dev: Device to update the links for. + * + * The probe has been successful, so update links from this device to any + * consumers by changing their status to "available". + * + * Also change the status of @dev's links to suppliers to "active". + */ +void device_links_driver_bound(struct device *dev) +{ + struct devlink *link; + int idx; + + idx = device_links_read_lock(); + + list_for_each_entry_rcu(link, &dev->supplier_links, s_node) { + spin_lock(&link->lock); + WARN_ON(link->status != DEVICE_LINK_DORMANT); + link->status = DEVICE_LINK_AVAILABLE; + spin_unlock(&link->lock); + } + + list_for_each_entry_rcu(link, &dev->consumer_links, c_node) { + spin_lock(&link->lock); + WARN_ON(link->status != DEVICE_LINK_CONSUMER_PROBE); + link->status = DEVICE_LINK_ACTIVE; + spin_unlock(&link->lock); + } + + device_links_read_unlock(idx); +} + +/** + * device_links_driver_gone - Update links after driver removal. + * @dev: Device whose driver has gone away. + * + * Update links to consumers for @dev by changing their status to "dormant". + */ +void device_links_driver_gone(struct device *dev) +{ + struct devlink *link; + int idx; + + idx = device_links_read_lock(); + + list_for_each_entry_rcu(link, &dev->supplier_links, s_node) { + WARN_ON(!(link->flags & DEVICE_LINK_PERSISTENT)); + spin_lock(&link->lock); + WARN_ON(link->status != DEVICE_LINK_SUPPLIER_UNBIND); + link->status = DEVICE_LINK_DORMANT; + spin_unlock(&link->lock); + } + + device_links_read_unlock(idx); +} + +/** + * device_links_no_driver - Update links of a device without a driver. + * @dev: Device without a drvier. + * + * Delete all non-persistent links from this device to any suppliers. + * Persistent links stay around, but their status is changed to "available", + * unless they already are in the "supplier unbind in progress" state in which + * case they need not be updated. + */ +void device_links_no_driver(struct device *dev) +{ + struct devlink *link, *ln; + + mutex_lock(&device_links_lock); + + list_for_each_entry_safe_reverse(link, ln, &dev->consumer_links, c_node) + if (link->flags & DEVICE_LINK_PERSISTENT) { + spin_lock(&link->lock); + + if (link->status != DEVICE_LINK_SUPPLIER_UNBIND) + link->status = DEVICE_LINK_AVAILABLE; + + spin_unlock(&link->lock); + } else { + devlink_del(link); + } + + mutex_unlock(&device_links_lock); +} + +/** + * device_links_busy - Check if there are any busy links to consumers. + * @dev: Device to check. + * + * Check each consumer of the device and return 'true' it if its link's status + * is one of "consumer probe" or "active" (meaning that the given consumer is + * probing right now or its driver is present). Otherwise, change the link + * state to "supplier unbind" to prevent the consumer from being probed + * successfully going forward. + * + * Return 'false' if there are no probing or active consumers. + */ +bool device_links_busy(struct device *dev) +{ + struct devlink *link; + int idx; + bool ret = false; + + idx = device_links_read_lock(); + + list_for_each_entry_rcu(link, &dev->supplier_links, s_node) { + spin_lock(&link->lock); + if (link->status == DEVICE_LINK_CONSUMER_PROBE + || link->status == DEVICE_LINK_ACTIVE) { + spin_unlock(&link->lock); + ret = true; + break; + } + link->status = DEVICE_LINK_SUPPLIER_UNBIND; + spin_unlock(&link->lock); + } + + device_links_read_unlock(idx); + return ret; +} + +/** + * device_links_unbind_consumers - Force unbind consumers of the given device. + * @dev: Device to unbind the consumers of. + * + * Walk the list of links to consumers for @dev and if any of them is in the + * "consumer probe" state, wait for all device probes in progress to complete + * and start over. + * + * If that's not the case, change the status of the link to "supplier unbind" + * and check if the link was in the "active" state. If so, force the consumer + * driver to unbind and start over (the consumer will not re-probe as we have + * changed the state of the link already). + */ +void device_links_unbind_consumers(struct device *dev) +{ + struct devlink *link; + int idx; + + start: + idx = device_links_read_lock(); + + list_for_each_entry_rcu(link, &dev->supplier_links, s_node) { + enum devlink_status status; + + spin_lock(&link->lock); + status = link->status; + if (status == DEVICE_LINK_CONSUMER_PROBE) { + spin_unlock(&link->lock); + + device_links_read_unlock(idx); + + wait_for_device_probe(); + goto start; + } + link->status = DEVICE_LINK_SUPPLIER_UNBIND; + if (status == DEVICE_LINK_ACTIVE) { + struct device *consumer = link->consumer; + + get_device(consumer); + spin_unlock(&link->lock); + + device_links_read_unlock(idx); + + device_release_driver_internal(consumer, NULL, + consumer->parent); + put_device(consumer); + goto start; + } + spin_unlock(&link->lock); + } + + device_links_read_unlock(idx); +} + +/* Device links support end. */ + int (*platform_notify)(struct device *dev) = NULL; int (*platform_notify_remove)(struct device *dev) = NULL; static struct kobject *dev_kobj; @@ -711,6 +1072,8 @@ void device_initialize(struct device *dev) #ifdef CONFIG_GENERIC_MSI_IRQ INIT_LIST_HEAD(&dev->msi_list); #endif + INIT_LIST_HEAD(&dev->supplier_links); + INIT_LIST_HEAD(&dev->consumer_links); } EXPORT_SYMBOL_GPL(device_initialize); @@ -1233,6 +1596,7 @@ void device_del(struct device *dev) { struct device *parent = dev->parent; struct class_interface *class_intf; + struct devlink *link, *ln; /* Notify clients of device removal. This call must come * before dpm_sysfs_remove(). @@ -1240,6 +1604,28 @@ void device_del(struct device *dev) if (dev->bus) blocking_notifier_call_chain(&dev->bus->p->bus_notifier, BUS_NOTIFY_DEL_DEVICE, dev); + + /* + * Delete all of the remaining links from this device to any other + * devices (either consumers or suppliers). + * + * This requires that all links be dormant, so warn if that's no the + * case. + */ + mutex_lock(&device_links_lock); + + list_for_each_entry_safe_reverse(link, ln, &dev->consumer_links, c_node) { + WARN_ON(link->status != DEVICE_LINK_DORMANT); + devlink_del(link); + } + + list_for_each_entry_safe_reverse(link, ln, &dev->supplier_links, s_node) { + WARN_ON(link->status != DEVICE_LINK_DORMANT); + devlink_del(link); + } + + mutex_unlock(&device_links_lock); + dpm_sysfs_remove(dev); if (parent) klist_del(&dev->p->knode_parent); diff --git a/drivers/base/dd.c b/drivers/base/dd.c index d9e76e9205c7..7c0abeba89e9 100644 --- a/drivers/base/dd.c +++ b/drivers/base/dd.c @@ -249,6 +249,7 @@ static void driver_bound(struct device *dev) __func__, dev_name(dev)); klist_add_tail(&dev->p->knode_driver, &dev->driver->p->klist_devices); + device_links_driver_bound(dev); device_pm_check_callbacks(dev); @@ -399,6 +400,7 @@ probe_failed: blocking_notifier_call_chain(&dev->bus->p->bus_notifier, BUS_NOTIFY_DRIVER_NOT_BOUND, dev); pinctrl_bind_failed: + device_links_no_driver(dev); devres_release_all(dev); driver_sysfs_remove(dev); dev->driver = NULL; @@ -489,6 +491,10 @@ int driver_probe_device(struct device_driver *drv, struct device *dev) if (!device_is_registered(dev)) return -ENODEV; + ret = device_links_check_suppliers(dev); + if (ret) + return ret; + pr_debug("bus: '%s': %s: matched device %s with driver %s\n", drv->bus->name, __func__, dev_name(dev), drv->name); @@ -756,7 +762,7 @@ EXPORT_SYMBOL_GPL(driver_attach); * __device_release_driver() must be called with @dev lock held. * When called for a USB interface, @dev->parent lock must be held as well. */ -static void __device_release_driver(struct device *dev) +static void __device_release_driver(struct device *dev, struct device *parent) { struct device_driver *drv; @@ -765,6 +771,25 @@ static void __device_release_driver(struct device *dev) if (driver_allows_async_probing(drv)) async_synchronize_full(); + while (device_links_busy(dev)) { + device_unlock(dev); + if (parent) + device_unlock(parent); + + device_links_unbind_consumers(dev); + if (parent) + device_lock(parent); + + device_lock(dev); + /* + * A concurrent invocation of the same function might + * have released the driver successfully while this one + * was waiting, so check for that. + */ + if (dev->driver != drv) + return; + } + pm_runtime_get_sync(dev); driver_sysfs_remove(dev); @@ -780,6 +805,9 @@ static void __device_release_driver(struct device *dev) dev->bus->remove(dev); else if (drv->remove) drv->remove(dev); + + device_links_driver_gone(dev); + device_links_no_driver(dev); devres_release_all(dev); dev->driver = NULL; dev_set_drvdata(dev, NULL); @@ -796,16 +824,16 @@ static void __device_release_driver(struct device *dev) } } -static void device_release_driver_internal(struct device *dev, - struct device_driver *drv, - struct device *parent) +void device_release_driver_internal(struct device *dev, + struct device_driver *drv, + struct device *parent) { if (parent) device_lock(parent); device_lock(dev); if (!drv || drv == dev->driver) - __device_release_driver(dev); + __device_release_driver(dev, parent); device_unlock(dev); if (parent) @@ -818,6 +846,10 @@ static void device_release_driver_internal(struct device *dev, * * Manually detach device from driver. * When called for a USB interface, @dev->parent lock must be held. + * + * If this function is to be called with @dev->parent lock held, ensure that + * the device's consumers are unbound in advance or that their locks can be + * acquired under the @dev->parent lock. */ void device_release_driver(struct device *dev) { diff --git a/include/linux/device.h b/include/linux/device.h index 38f02814d53a..647204bd74a0 100644 --- a/include/linux/device.h +++ b/include/linux/device.h @@ -706,6 +706,34 @@ struct device_dma_parameters { unsigned long segment_boundary_mask; }; +enum devlink_status { + DEVICE_LINK_DORMANT = 0, /* Link not in use. */ + DEVICE_LINK_AVAILABLE, /* Supplier driver is present. */ + DEVICE_LINK_ACTIVE, /* Consumer driver is present too. */ + DEVICE_LINK_CONSUMER_PROBE, /* Consumer is probing. */ + DEVICE_LINK_SUPPLIER_UNBIND, /* Supplier is unbinding. */ +}; + +/* + * Device link flags. + * + * PERSISTENT: Do not delete the link on consumer device driver unbind. + * PROBE_TIME: Assume supplier device functional when creating the link. + */ +#define DEVICE_LINK_PERSISTENT (1 << 0) +#define DEVICE_LINK_PROBE_TIME (1 << 1) + +struct devlink { + struct device *supplier; + struct list_head s_node; + struct device *consumer; + struct list_head c_node; + enum devlink_status status; + u32 flags; + spinlock_t lock; + struct rcu_head rcu_head; +}; + /** * struct device - The basic device structure * @parent: The device's "parent" device, the device to which it is attached. @@ -731,6 +759,8 @@ struct device_dma_parameters { * on. This shrinks the "Board Support Packages" (BSPs) and * minimizes board-specific #ifdefs in drivers. * @driver_data: Private pointer for driver specific info. + * @supplier_links: Links to consumer devices. + * @consumer_links: Links to supplier devices. * @power: For device power management. * See Documentation/power/devices.txt for details. * @pm_domain: Provide callbacks that are executed during system suspend, @@ -797,6 +827,8 @@ struct device { core doesn't touch it */ void *driver_data; /* Driver data, set and get with dev_set/get_drvdata */ + struct list_head supplier_links; + struct list_head consumer_links; struct dev_pm_info power; struct dev_pm_domain *pm_domain; @@ -1113,6 +1145,10 @@ extern void device_shutdown(void); /* debugging and troubleshooting/diagnostic helpers. */ extern const char *dev_driver_string(const struct device *dev); +/* Device links interface. */ +struct devlink *device_link_add(struct device *consumer, + struct device *supplier, u32 flags); +void device_link_del(struct devlink *link); #ifdef CONFIG_PRINTK -- 1.9.1