diff options
Diffstat (limited to 'drivers/base/core.c')
| -rw-r--r-- | drivers/base/core.c | 88 |
1 files changed, 88 insertions, 0 deletions
diff --git a/drivers/base/core.c b/drivers/base/core.c index 510fabf8918c..b3896da73b3d 100644 --- a/drivers/base/core.c +++ b/drivers/base/core.c @@ -44,6 +44,8 @@ early_param("sysfs.deprecated", sysfs_deprecated_setup); #endif /* Device links support. */ +static LIST_HEAD(wait_for_suppliers); +static DEFINE_MUTEX(wfs_lock); #ifdef CONFIG_SRCU static DEFINE_MUTEX(device_links_lock); @@ -430,6 +432,58 @@ 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)) @@ -564,6 +618,17 @@ 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) { @@ -848,6 +913,10 @@ 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). @@ -1712,6 +1781,7 @@ 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); dev->links.status = DL_DEV_NO_DRIVER; } EXPORT_SYMBOL_GPL(device_initialize); @@ -2202,6 +2272,24 @@ int device_add(struct device *dev) 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, |