diff options
Diffstat (limited to 'drivers/base/core.c')
| -rw-r--r-- | drivers/base/core.c | 167 |
1 files changed, 167 insertions, 0 deletions
diff --git a/drivers/base/core.c b/drivers/base/core.c index 7bd9cd366d41..7ea665a97da2 100644 --- a/drivers/base/core.c +++ b/drivers/base/core.c @@ -45,6 +45,10 @@ 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; #ifdef CONFIG_SRCU static DEFINE_MUTEX(device_links_lock); @@ -431,6 +435,58 @@ struct device_link *device_link_add(struct device *consumer, } 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) +{ + mutex_lock(&wfs_lock); + list_add_tail(&consumer->links.needs_suppliers, &wait_for_suppliers); + mutex_unlock(&wfs_lock); +} + +/** + * 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) + if (!fwnode_call_int_op(dev->fwnode, add_links, dev)) + list_del_init(&dev->links.needs_suppliers); + mutex_unlock(&wfs_lock); +} + static void device_link_free(struct device_link *link) { while (refcount_dec_not_one(&link->rpm_active)) @@ -565,6 +621,17 @@ int device_links_check_suppliers(struct device *dev) struct device_link *link; int ret = 0; + /* + * Device waiting for supplier to become available is not allowed to + * probe. + */ + mutex_lock(&wfs_lock); + if (!list_empty(&dev->links.needs_suppliers)) { + mutex_unlock(&wfs_lock); + return -EPROBE_DEFER; + } + mutex_unlock(&wfs_lock); + device_links_write_lock(); list_for_each_entry(link, &dev->links.suppliers, c_node) { @@ -584,6 +651,69 @@ int device_links_check_suppliers(struct device *dev) return ret; } +static void __device_links_supplier_sync_state(struct device *dev) +{ + struct device_link *link; + + if (dev->state_synced) + return; + + list_for_each_entry(link, &dev->links.consumers, s_node) { + if (!(link->flags & DL_FLAG_MANAGED)) + continue; + if (link->status != DL_STATE_ACTIVE) + return; + } + + if (dev->bus->sync_state) + dev->bus->sync_state(dev); + else if (dev->driver && dev->driver->sync_state) + dev->driver->sync_state(dev); + + dev->state_synced = true; +} + +void device_links_supplier_sync_state_pause(void) +{ + device_links_write_lock(); + defer_sync_state_count++; + device_links_write_unlock(); +} + +void device_links_supplier_sync_state_resume(void) +{ + struct device *dev, *tmp; + + device_links_write_lock(); + if (!defer_sync_state_count) { + WARN(true, "Unmatched sync_state pause/resume!"); + goto out; + } + defer_sync_state_count--; + if (defer_sync_state_count) + goto out; + + list_for_each_entry_safe(dev, tmp, &deferred_sync, links.defer_sync) { + __device_links_supplier_sync_state(dev); + list_del_init(&dev->links.defer_sync); + } +out: + device_links_write_unlock(); +} + +static int sync_state_resume_initcall(void) +{ + device_links_supplier_sync_state_resume(); + return 0; +} +late_initcall(sync_state_resume_initcall); + +static void __device_links_supplier_defer_sync(struct device *sup) +{ + if (list_empty(&sup->links.defer_sync)) + list_add_tail(&sup->links.defer_sync, &deferred_sync); +} + /** * device_links_driver_bound - Update device links after probing its driver. * @dev: Device to update the links for. @@ -628,6 +758,11 @@ void device_links_driver_bound(struct device *dev) WARN_ON(link->status != DL_STATE_CONSUMER_PROBE); WRITE_ONCE(link->status, DL_STATE_ACTIVE); + + if (defer_sync_state_count) + __device_links_supplier_defer_sync(link->supplier); + else + __device_links_supplier_sync_state(link->supplier); } dev->links.status = DL_DEV_DRIVER_BOUND; @@ -744,6 +879,7 @@ void device_links_driver_cleanup(struct device *dev) WRITE_ONCE(link->status, DL_STATE_DORMANT); } + list_del_init(&dev->links.defer_sync); __device_links_no_driver(dev); device_links_write_unlock(); @@ -849,6 +985,10 @@ static void device_links_purge(struct device *dev) { struct device_link *link, *ln; + mutex_lock(&wfs_lock); + list_del(&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). @@ -1713,6 +1853,8 @@ 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; } EXPORT_SYMBOL_GPL(device_initialize); @@ -2199,6 +2341,28 @@ int device_add(struct device *dev) BUS_NOTIFY_ADD_DEVICE, dev); kobject_uevent(&dev->kobj, KOBJ_ADD); + + if (dev->fwnode && !dev->fwnode->dev) + dev->fwnode->dev = dev; + + /* + * Check if any of the other devices (consumers) have been waiting for + * this device (supplier) to be added so that they can create a device + * link to it. + * + * This needs to happen after device_pm_add() because device_link_add() + * requires the supplier be registered before it's called. + * + * But this also needs to happe before bus_probe_device() to make sure + * waiting consumers can link to it before the driver is bound to the + * device and the driver sync_state callback is called for this device. + */ + device_link_add_missing_supplier_links(); + + if (fwnode_has_op(dev->fwnode, add_links) + && fwnode_call_int_op(dev->fwnode, add_links, dev)) + device_link_wait_for_supplier(dev); + bus_probe_device(dev); if (parent) klist_add_tail(&dev->p->knode_parent, @@ -2343,6 +2507,9 @@ void device_del(struct device *dev) kill_device(dev); device_unlock(dev); + if (dev->fwnode && dev->fwnode->dev == dev) + dev->fwnode->dev = NULL; + /* Notify clients of device removal. This call must come * before dpm_sysfs_remove(). */ |