diff options
| -rw-r--r-- | drivers/base/core.c | 325 | ||||
| -rw-r--r-- | include/linux/device.h | 5 |
2 files changed, 238 insertions, 92 deletions
diff --git a/drivers/base/core.c b/drivers/base/core.c index 8a973d9601d3..9edf9084fc98 100644 --- a/drivers/base/core.c +++ b/drivers/base/core.c @@ -46,8 +46,6 @@ early_param("sysfs.deprecated", sysfs_deprecated_setup); #endif /* Device links support. */ -static LIST_HEAD(wait_for_suppliers); -static DEFINE_MUTEX(wfs_lock); static LIST_HEAD(deferred_sync); static unsigned int defer_sync_state_count = 1; static DEFINE_MUTEX(fwnode_link_lock); @@ -803,74 +801,6 @@ out: } EXPORT_SYMBOL_GPL(device_link_add); -/** - * device_link_wait_for_supplier - Add device to wait_for_suppliers list - * @consumer: Consumer device - * - * Marks the @consumer device as waiting for suppliers to become available by - * adding it to the wait_for_suppliers list. The consumer device will never be - * probed until it's removed from the wait_for_suppliers list. - * - * The caller is responsible for adding the links to the supplier devices once - * they are available and removing the @consumer device from the - * wait_for_suppliers list once links to all the suppliers have been created. - * - * This function is NOT meant to be called from the probe function of the - * consumer but rather from code that creates/adds the consumer device. - */ -static void device_link_wait_for_supplier(struct device *consumer, - bool need_for_probe) -{ - mutex_lock(&wfs_lock); - list_add_tail(&consumer->links.needs_suppliers, &wait_for_suppliers); - consumer->links.need_for_probe = need_for_probe; - mutex_unlock(&wfs_lock); -} - -static void device_link_wait_for_mandatory_supplier(struct device *consumer) -{ - device_link_wait_for_supplier(consumer, true); -} - -static void device_link_wait_for_optional_supplier(struct device *consumer) -{ - device_link_wait_for_supplier(consumer, false); -} - -/** - * device_link_add_missing_supplier_links - Add links from consumer devices to - * supplier devices, leaving any - * consumer with inactive suppliers on - * the wait_for_suppliers list - * - * Loops through all consumers waiting on suppliers and tries to add all their - * supplier links. If that succeeds, the consumer device is removed from - * wait_for_suppliers list. Otherwise, they are left in the wait_for_suppliers - * list. Devices left on the wait_for_suppliers list will not be probed. - * - * The fwnode add_links callback is expected to return 0 if it has found and - * added all the supplier links for the consumer device. It should return an - * error if it isn't able to do so. - * - * The caller of device_link_wait_for_supplier() is expected to call this once - * it's aware of potential suppliers becoming available. - */ -static void device_link_add_missing_supplier_links(void) -{ - struct device *dev, *tmp; - - mutex_lock(&wfs_lock); - list_for_each_entry_safe(dev, tmp, &wait_for_suppliers, - links.needs_suppliers) { - int ret = fwnode_call_int_op(dev->fwnode, add_links, dev); - if (!ret) - list_del_init(&dev->links.needs_suppliers); - else if (ret != -ENODEV) - dev->links.need_for_probe = false; - } - mutex_unlock(&wfs_lock); -} - #ifdef CONFIG_SRCU static void __device_link_del(struct kref *kref) { @@ -1195,9 +1125,8 @@ void device_links_driver_bound(struct device *dev) * the device links it needs to or make new device links as it needs * them. So, it no longer needs to wait on any suppliers. */ - mutex_lock(&wfs_lock); - list_del_init(&dev->links.needs_suppliers); - mutex_unlock(&wfs_lock); + if (dev->fwnode && dev->fwnode->dev == dev) + fwnode_links_purge_suppliers(dev->fwnode); device_remove_file(dev, &dev_attr_waiting_for_supplier); device_links_write_lock(); @@ -1488,10 +1417,6 @@ static void device_links_purge(struct device *dev) if (dev->class == &devlink_class) return; - mutex_lock(&wfs_lock); - list_del_init(&dev->links.needs_suppliers); - mutex_unlock(&wfs_lock); - /* * Delete all of the remaining links from this device to any other * devices (either consumers or suppliers). @@ -1561,19 +1486,246 @@ static void fw_devlink_parse_fwtree(struct fwnode_handle *fwnode) fw_devlink_parse_fwtree(child); } -static void fw_devlink_link_device(struct device *dev) +/** + * fw_devlink_create_devlink - Create a device link from a consumer to fwnode + * @con - Consumer device for the device link + * @sup_handle - fwnode handle of supplier + * + * This function will try to create a device link between the consumer device + * @con and the supplier device represented by @sup_handle. + * + * 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 it cannot create a + * device link from the consumer to a missing supplier. + * + * Returns, + * 0 on successfully creating a device link + * -EINVAL if the device link cannot be created as expected + * -EAGAIN if the device link cannot be created right now, but it may be + * possible to do that in the future + */ +static int fw_devlink_create_devlink(struct device *con, + struct fwnode_handle *sup_handle, u32 flags) +{ + struct device *sup_dev; + int ret = 0; + + sup_dev = get_dev_from_fwnode(sup_handle); + if (sup_dev) { + /* + * If this fails, it 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; + + goto out; + } + + /* + * 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; + + /* + * If we can't find the supplier device from its fwnode, it might be + * due to a cyclic dependency 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 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. + */ + sup_dev = fwnode_get_next_parent_dev(sup_handle); + if (sup_dev && device_is_dependent(con, sup_dev)) { + dev_dbg(con, "Not linking to %pfwP - False link\n", + sup_handle); + ret = -EINVAL; + } else { + /* + * Can't check for cycles or no cycles. So let's try + * again later. + */ + ret = -EAGAIN; + } + +out: + 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. + * + * 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. See + * fw_devlink_create_devlink() for more details. + * + * 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) { - int fw_ret; + 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; - device_link_add_missing_supplier_links(); + 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; - if (fw_devlink_flags && fwnode_has_op(dev->fwnode, add_links)) { - fw_ret = fwnode_call_int_op(dev->fwnode, add_links, dev); - if (fw_ret == -ENODEV && !fw_devlink_is_permissive()) - device_link_wait_for_mandatory_supplier(dev); - else if (fw_ret) - device_link_wait_for_optional_supplier(dev); + 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) +{ + struct fwnode_handle *fwnode = dev->fwnode; + + if (!fw_devlink_flags) + return; + + fw_devlink_parse_fwtree(fwnode); + + mutex_lock(&fwnode_link_lock); + __fw_devlink_link_to_consumers(dev); + __fw_devlink_link_to_suppliers(dev, fwnode); + mutex_unlock(&fwnode_link_lock); } /* Device links support end. */ @@ -2431,7 +2583,6 @@ void device_initialize(struct device *dev) #endif INIT_LIST_HEAD(&dev->links.consumers); INIT_LIST_HEAD(&dev->links.suppliers); - INIT_LIST_HEAD(&dev->links.needs_suppliers); INIT_LIST_HEAD(&dev->links.defer_sync); dev->links.status = DL_DEV_NO_DRIVER; } diff --git a/include/linux/device.h b/include/linux/device.h index 1e771ea4dca6..89bb8b84173e 100644 --- a/include/linux/device.h +++ b/include/linux/device.h @@ -351,18 +351,13 @@ enum dl_dev_state { * struct dev_links_info - Device data related to device links. * @suppliers: List of links to supplier devices. * @consumers: List of links to consumer devices. - * @needs_suppliers: Hook to global list of devices waiting for suppliers. * @defer_sync: Hook to global list of devices that have deferred sync_state. - * @need_for_probe: If needs_suppliers is on a list, this indicates if the - * suppliers are needed for probe or not. * @status: Driver status information. */ struct dev_links_info { struct list_head suppliers; struct list_head consumers; - struct list_head needs_suppliers; struct list_head defer_sync; - bool need_for_probe; enum dl_dev_state status; }; |