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Diffstat (limited to '')
| -rw-r--r-- | drivers/base/dd.c | 1287 |
1 files changed, 1287 insertions, 0 deletions
diff --git a/drivers/base/dd.c b/drivers/base/dd.c new file mode 100644 index 000000000..1e8318acf --- /dev/null +++ b/drivers/base/dd.c @@ -0,0 +1,1287 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * drivers/base/dd.c - The core device/driver interactions. + * + * This file contains the (sometimes tricky) code that controls the + * interactions between devices and drivers, which primarily includes + * driver binding and unbinding. + * + * All of this code used to exist in drivers/base/bus.c, but was + * relocated to here in the name of compartmentalization (since it wasn't + * strictly code just for the 'struct bus_type'. + * + * Copyright (c) 2002-5 Patrick Mochel + * Copyright (c) 2002-3 Open Source Development Labs + * Copyright (c) 2007-2009 Greg Kroah-Hartman <gregkh@suse.de> + * Copyright (c) 2007-2009 Novell Inc. + */ + +#include <linux/debugfs.h> +#include <linux/device.h> +#include <linux/delay.h> +#include <linux/dma-map-ops.h> +#include <linux/init.h> +#include <linux/module.h> +#include <linux/kthread.h> +#include <linux/wait.h> +#include <linux/async.h> +#include <linux/pm_runtime.h> +#include <linux/pinctrl/devinfo.h> +#include <linux/slab.h> + +#include "base.h" +#include "power/power.h" + +/* + * Deferred Probe infrastructure. + * + * Sometimes driver probe order matters, but the kernel doesn't always have + * dependency information which means some drivers will get probed before a + * resource it depends on is available. For example, an SDHCI driver may + * first need a GPIO line from an i2c GPIO controller before it can be + * initialized. If a required resource is not available yet, a driver can + * request probing to be deferred by returning -EPROBE_DEFER from its probe hook + * + * Deferred probe maintains two lists of devices, a pending list and an active + * list. A driver returning -EPROBE_DEFER causes the device to be added to the + * pending list. A successful driver probe will trigger moving all devices + * from the pending to the active list so that the workqueue will eventually + * retry them. + * + * The deferred_probe_mutex must be held any time the deferred_probe_*_list + * of the (struct device*)->p->deferred_probe pointers are manipulated + */ +static DEFINE_MUTEX(deferred_probe_mutex); +static LIST_HEAD(deferred_probe_pending_list); +static LIST_HEAD(deferred_probe_active_list); +static atomic_t deferred_trigger_count = ATOMIC_INIT(0); +static struct dentry *deferred_devices; +static bool initcalls_done; + +/* Save the async probe drivers' name from kernel cmdline */ +#define ASYNC_DRV_NAMES_MAX_LEN 256 +static char async_probe_drv_names[ASYNC_DRV_NAMES_MAX_LEN]; + +/* + * In some cases, like suspend to RAM or hibernation, It might be reasonable + * to prohibit probing of devices as it could be unsafe. + * Once defer_all_probes is true all drivers probes will be forcibly deferred. + */ +static bool defer_all_probes; + +/* + * deferred_probe_work_func() - Retry probing devices in the active list. + */ +static void deferred_probe_work_func(struct work_struct *work) +{ + struct device *dev; + struct device_private *private; + /* + * This block processes every device in the deferred 'active' list. + * Each device is removed from the active list and passed to + * bus_probe_device() to re-attempt the probe. The loop continues + * until every device in the active list is removed and retried. + * + * Note: Once the device is removed from the list and the mutex is + * released, it is possible for the device get freed by another thread + * and cause a illegal pointer dereference. This code uses + * get/put_device() to ensure the device structure cannot disappear + * from under our feet. + */ + mutex_lock(&deferred_probe_mutex); + while (!list_empty(&deferred_probe_active_list)) { + private = list_first_entry(&deferred_probe_active_list, + typeof(*dev->p), deferred_probe); + dev = private->device; + list_del_init(&private->deferred_probe); + + get_device(dev); + + kfree(dev->p->deferred_probe_reason); + dev->p->deferred_probe_reason = NULL; + + /* + * Drop the mutex while probing each device; the probe path may + * manipulate the deferred list + */ + mutex_unlock(&deferred_probe_mutex); + + /* + * Force the device to the end of the dpm_list since + * the PM code assumes that the order we add things to + * the list is a good order for suspend but deferred + * probe makes that very unsafe. + */ + device_pm_move_to_tail(dev); + + dev_dbg(dev, "Retrying from deferred list\n"); + bus_probe_device(dev); + mutex_lock(&deferred_probe_mutex); + + put_device(dev); + } + mutex_unlock(&deferred_probe_mutex); +} +static DECLARE_WORK(deferred_probe_work, deferred_probe_work_func); + +void driver_deferred_probe_add(struct device *dev) +{ + mutex_lock(&deferred_probe_mutex); + if (list_empty(&dev->p->deferred_probe)) { + dev_dbg(dev, "Added to deferred list\n"); + list_add_tail(&dev->p->deferred_probe, &deferred_probe_pending_list); + } + mutex_unlock(&deferred_probe_mutex); +} + +void driver_deferred_probe_del(struct device *dev) +{ + mutex_lock(&deferred_probe_mutex); + if (!list_empty(&dev->p->deferred_probe)) { + dev_dbg(dev, "Removed from deferred list\n"); + list_del_init(&dev->p->deferred_probe); + kfree(dev->p->deferred_probe_reason); + dev->p->deferred_probe_reason = NULL; + } + mutex_unlock(&deferred_probe_mutex); +} + +static bool driver_deferred_probe_enable = false; +/** + * driver_deferred_probe_trigger() - Kick off re-probing deferred devices + * + * This functions moves all devices from the pending list to the active + * list and schedules the deferred probe workqueue to process them. It + * should be called anytime a driver is successfully bound to a device. + * + * Note, there is a race condition in multi-threaded probe. In the case where + * more than one device is probing at the same time, it is possible for one + * probe to complete successfully while another is about to defer. If the second + * depends on the first, then it will get put on the pending list after the + * trigger event has already occurred and will be stuck there. + * + * The atomic 'deferred_trigger_count' is used to determine if a successful + * trigger has occurred in the midst of probing a driver. If the trigger count + * changes in the midst of a probe, then deferred processing should be triggered + * again. + */ +static void driver_deferred_probe_trigger(void) +{ + if (!driver_deferred_probe_enable) + return; + + /* + * A successful probe means that all the devices in the pending list + * should be triggered to be reprobed. Move all the deferred devices + * into the active list so they can be retried by the workqueue + */ + mutex_lock(&deferred_probe_mutex); + atomic_inc(&deferred_trigger_count); + list_splice_tail_init(&deferred_probe_pending_list, + &deferred_probe_active_list); + mutex_unlock(&deferred_probe_mutex); + + /* + * Kick the re-probe thread. It may already be scheduled, but it is + * safe to kick it again. + */ + schedule_work(&deferred_probe_work); +} + +/** + * device_block_probing() - Block/defer device's probes + * + * It will disable probing of devices and defer their probes instead. + */ +void device_block_probing(void) +{ + defer_all_probes = true; + /* sync with probes to avoid races. */ + wait_for_device_probe(); +} + +/** + * device_unblock_probing() - Unblock/enable device's probes + * + * It will restore normal behavior and trigger re-probing of deferred + * devices. + */ +void device_unblock_probing(void) +{ + defer_all_probes = false; + driver_deferred_probe_trigger(); +} + +/** + * device_set_deferred_probe_reason() - Set defer probe reason message for device + * @dev: the pointer to the struct device + * @vaf: the pointer to va_format structure with message + */ +void device_set_deferred_probe_reason(const struct device *dev, struct va_format *vaf) +{ + const char *drv = dev_driver_string(dev); + + mutex_lock(&deferred_probe_mutex); + + kfree(dev->p->deferred_probe_reason); + dev->p->deferred_probe_reason = kasprintf(GFP_KERNEL, "%s: %pV", drv, vaf); + + mutex_unlock(&deferred_probe_mutex); +} + +/* + * deferred_devs_show() - Show the devices in the deferred probe pending list. + */ +static int deferred_devs_show(struct seq_file *s, void *data) +{ + struct device_private *curr; + + mutex_lock(&deferred_probe_mutex); + + list_for_each_entry(curr, &deferred_probe_pending_list, deferred_probe) + seq_printf(s, "%s\t%s", dev_name(curr->device), + curr->device->p->deferred_probe_reason ?: "\n"); + + mutex_unlock(&deferred_probe_mutex); + + return 0; +} +DEFINE_SHOW_ATTRIBUTE(deferred_devs); + +int driver_deferred_probe_timeout; +EXPORT_SYMBOL_GPL(driver_deferred_probe_timeout); + +static int __init deferred_probe_timeout_setup(char *str) +{ + int timeout; + + if (!kstrtoint(str, 10, &timeout)) + driver_deferred_probe_timeout = timeout; + return 1; +} +__setup("deferred_probe_timeout=", deferred_probe_timeout_setup); + +/** + * driver_deferred_probe_check_state() - Check deferred probe state + * @dev: device to check + * + * Return: + * -ENODEV if initcalls have completed and modules are disabled. + * -ETIMEDOUT if the deferred probe timeout was set and has expired + * and modules are enabled. + * -EPROBE_DEFER in other cases. + * + * Drivers or subsystems can opt-in to calling this function instead of directly + * returning -EPROBE_DEFER. + */ +int driver_deferred_probe_check_state(struct device *dev) +{ + if (!IS_ENABLED(CONFIG_MODULES) && initcalls_done) { + dev_warn(dev, "ignoring dependency for device, assuming no driver\n"); + return -ENODEV; + } + + if (!driver_deferred_probe_timeout && initcalls_done) { + dev_warn(dev, "deferred probe timeout, ignoring dependency\n"); + return -ETIMEDOUT; + } + + return -EPROBE_DEFER; +} + +static void deferred_probe_timeout_work_func(struct work_struct *work) +{ + struct device_private *p; + + driver_deferred_probe_timeout = 0; + driver_deferred_probe_trigger(); + flush_work(&deferred_probe_work); + + mutex_lock(&deferred_probe_mutex); + list_for_each_entry(p, &deferred_probe_pending_list, deferred_probe) + dev_info(p->device, "deferred probe pending\n"); + mutex_unlock(&deferred_probe_mutex); +} +static DECLARE_DELAYED_WORK(deferred_probe_timeout_work, deferred_probe_timeout_work_func); + +/** + * deferred_probe_initcall() - Enable probing of deferred devices + * + * We don't want to get in the way when the bulk of drivers are getting probed. + * Instead, this initcall makes sure that deferred probing is delayed until + * late_initcall time. + */ +static int deferred_probe_initcall(void) +{ + deferred_devices = debugfs_create_file("devices_deferred", 0444, NULL, + NULL, &deferred_devs_fops); + + driver_deferred_probe_enable = true; + driver_deferred_probe_trigger(); + /* Sort as many dependencies as possible before exiting initcalls */ + flush_work(&deferred_probe_work); + initcalls_done = true; + + /* + * Trigger deferred probe again, this time we won't defer anything + * that is optional + */ + driver_deferred_probe_trigger(); + flush_work(&deferred_probe_work); + + if (driver_deferred_probe_timeout > 0) { + schedule_delayed_work(&deferred_probe_timeout_work, + driver_deferred_probe_timeout * HZ); + } + return 0; +} +late_initcall(deferred_probe_initcall); + +static void __exit deferred_probe_exit(void) +{ + debugfs_remove_recursive(deferred_devices); +} +__exitcall(deferred_probe_exit); + +/** + * device_is_bound() - Check if device is bound to a driver + * @dev: device to check + * + * Returns true if passed device has already finished probing successfully + * against a driver. + * + * This function must be called with the device lock held. + */ +bool device_is_bound(struct device *dev) +{ + return dev->p && klist_node_attached(&dev->p->knode_driver); +} + +static void driver_bound(struct device *dev) +{ + if (device_is_bound(dev)) { + pr_warn("%s: device %s already bound\n", + __func__, kobject_name(&dev->kobj)); + return; + } + + pr_debug("driver: '%s': %s: bound to device '%s'\n", dev->driver->name, + __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); + + /* + * Make sure the device is no longer in one of the deferred lists and + * kick off retrying all pending devices + */ + driver_deferred_probe_del(dev); + driver_deferred_probe_trigger(); + + if (dev->bus) + blocking_notifier_call_chain(&dev->bus->p->bus_notifier, + BUS_NOTIFY_BOUND_DRIVER, dev); + + kobject_uevent(&dev->kobj, KOBJ_BIND); +} + +static ssize_t coredump_store(struct device *dev, struct device_attribute *attr, + const char *buf, size_t count) +{ + device_lock(dev); + dev->driver->coredump(dev); + device_unlock(dev); + + return count; +} +static DEVICE_ATTR_WO(coredump); + +static int driver_sysfs_add(struct device *dev) +{ + int ret; + + if (dev->bus) + blocking_notifier_call_chain(&dev->bus->p->bus_notifier, + BUS_NOTIFY_BIND_DRIVER, dev); + + ret = sysfs_create_link(&dev->driver->p->kobj, &dev->kobj, + kobject_name(&dev->kobj)); + if (ret) + goto fail; + + ret = sysfs_create_link(&dev->kobj, &dev->driver->p->kobj, + "driver"); + if (ret) + goto rm_dev; + + if (!IS_ENABLED(CONFIG_DEV_COREDUMP) || !dev->driver->coredump || + !device_create_file(dev, &dev_attr_coredump)) + return 0; + + sysfs_remove_link(&dev->kobj, "driver"); + +rm_dev: + sysfs_remove_link(&dev->driver->p->kobj, + kobject_name(&dev->kobj)); + +fail: + return ret; +} + +static void driver_sysfs_remove(struct device *dev) +{ + struct device_driver *drv = dev->driver; + + if (drv) { + if (drv->coredump) + device_remove_file(dev, &dev_attr_coredump); + sysfs_remove_link(&drv->p->kobj, kobject_name(&dev->kobj)); + sysfs_remove_link(&dev->kobj, "driver"); + } +} + +/** + * device_bind_driver - bind a driver to one device. + * @dev: device. + * + * Allow manual attachment of a driver to a device. + * Caller must have already set @dev->driver. + * + * Note that this does not modify the bus reference count. + * Please verify that is accounted for before calling this. + * (It is ok to call with no other effort from a driver's probe() method.) + * + * This function must be called with the device lock held. + */ +int device_bind_driver(struct device *dev) +{ + int ret; + + ret = driver_sysfs_add(dev); + if (!ret) + driver_bound(dev); + else if (dev->bus) + blocking_notifier_call_chain(&dev->bus->p->bus_notifier, + BUS_NOTIFY_DRIVER_NOT_BOUND, dev); + return ret; +} +EXPORT_SYMBOL_GPL(device_bind_driver); + +static atomic_t probe_count = ATOMIC_INIT(0); +static DECLARE_WAIT_QUEUE_HEAD(probe_waitqueue); + +static void driver_deferred_probe_add_trigger(struct device *dev, + int local_trigger_count) +{ + driver_deferred_probe_add(dev); + /* Did a trigger occur while probing? Need to re-trigger if yes */ + if (local_trigger_count != atomic_read(&deferred_trigger_count)) + driver_deferred_probe_trigger(); +} + +static ssize_t state_synced_show(struct device *dev, + struct device_attribute *attr, char *buf) +{ + bool val; + + device_lock(dev); + val = dev->state_synced; + device_unlock(dev); + + return sysfs_emit(buf, "%u\n", val); +} +static DEVICE_ATTR_RO(state_synced); + +static int really_probe(struct device *dev, struct device_driver *drv) +{ + int ret = -EPROBE_DEFER; + int local_trigger_count = atomic_read(&deferred_trigger_count); + bool test_remove = IS_ENABLED(CONFIG_DEBUG_TEST_DRIVER_REMOVE) && + !drv->suppress_bind_attrs; + + if (defer_all_probes) { + /* + * Value of defer_all_probes can be set only by + * device_block_probing() which, in turn, will call + * wait_for_device_probe() right after that to avoid any races. + */ + dev_dbg(dev, "Driver %s force probe deferral\n", drv->name); + driver_deferred_probe_add(dev); + return ret; + } + + ret = device_links_check_suppliers(dev); + if (ret == -EPROBE_DEFER) + driver_deferred_probe_add_trigger(dev, local_trigger_count); + if (ret) + return ret; + + atomic_inc(&probe_count); + pr_debug("bus: '%s': %s: probing driver %s with device %s\n", + drv->bus->name, __func__, drv->name, dev_name(dev)); + if (!list_empty(&dev->devres_head)) { + dev_crit(dev, "Resources present before probing\n"); + ret = -EBUSY; + goto done; + } + +re_probe: + dev->driver = drv; + + /* If using pinctrl, bind pins now before probing */ + ret = pinctrl_bind_pins(dev); + if (ret) + goto pinctrl_bind_failed; + + if (dev->bus->dma_configure) { + ret = dev->bus->dma_configure(dev); + if (ret) + goto probe_failed; + } + + ret = driver_sysfs_add(dev); + if (ret) { + pr_err("%s: driver_sysfs_add(%s) failed\n", + __func__, dev_name(dev)); + goto probe_failed; + } + + if (dev->pm_domain && dev->pm_domain->activate) { + ret = dev->pm_domain->activate(dev); + if (ret) + goto probe_failed; + } + + if (dev->bus->probe) { + ret = dev->bus->probe(dev); + if (ret) + goto probe_failed; + } else if (drv->probe) { + ret = drv->probe(dev); + if (ret) + goto probe_failed; + } + + ret = device_add_groups(dev, drv->dev_groups); + if (ret) { + dev_err(dev, "device_add_groups() failed\n"); + goto dev_groups_failed; + } + + if (dev_has_sync_state(dev)) { + ret = device_create_file(dev, &dev_attr_state_synced); + if (ret) { + dev_err(dev, "state_synced sysfs add failed\n"); + goto dev_sysfs_state_synced_failed; + } + } + + if (test_remove) { + test_remove = false; + + device_remove_file(dev, &dev_attr_state_synced); + device_remove_groups(dev, drv->dev_groups); + + if (dev->bus->remove) + dev->bus->remove(dev); + else if (drv->remove) + drv->remove(dev); + + devres_release_all(dev); + arch_teardown_dma_ops(dev); + kfree(dev->dma_range_map); + dev->dma_range_map = NULL; + driver_sysfs_remove(dev); + dev->driver = NULL; + dev_set_drvdata(dev, NULL); + if (dev->pm_domain && dev->pm_domain->dismiss) + dev->pm_domain->dismiss(dev); + pm_runtime_reinit(dev); + + goto re_probe; + } + + pinctrl_init_done(dev); + + if (dev->pm_domain && dev->pm_domain->sync) + dev->pm_domain->sync(dev); + + driver_bound(dev); + ret = 1; + pr_debug("bus: '%s': %s: bound device %s to driver %s\n", + drv->bus->name, __func__, dev_name(dev), drv->name); + goto done; + +dev_sysfs_state_synced_failed: + device_remove_groups(dev, drv->dev_groups); +dev_groups_failed: + if (dev->bus->remove) + dev->bus->remove(dev); + else if (drv->remove) + drv->remove(dev); +probe_failed: + if (dev->bus) + 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); + arch_teardown_dma_ops(dev); + kfree(dev->dma_range_map); + dev->dma_range_map = NULL; + driver_sysfs_remove(dev); + dev->driver = NULL; + dev_set_drvdata(dev, NULL); + if (dev->pm_domain && dev->pm_domain->dismiss) + dev->pm_domain->dismiss(dev); + pm_runtime_reinit(dev); + dev_pm_set_driver_flags(dev, 0); + + switch (ret) { + case -EPROBE_DEFER: + /* Driver requested deferred probing */ + dev_dbg(dev, "Driver %s requests probe deferral\n", drv->name); + driver_deferred_probe_add_trigger(dev, local_trigger_count); + break; + case -ENODEV: + case -ENXIO: + pr_debug("%s: probe of %s rejects match %d\n", + drv->name, dev_name(dev), ret); + break; + default: + /* driver matched but the probe failed */ + pr_warn("%s: probe of %s failed with error %d\n", + drv->name, dev_name(dev), ret); + } + /* + * Ignore errors returned by ->probe so that the next driver can try + * its luck. + */ + ret = 0; +done: + atomic_dec(&probe_count); + wake_up_all(&probe_waitqueue); + return ret; +} + +/* + * For initcall_debug, show the driver probe time. + */ +static int really_probe_debug(struct device *dev, struct device_driver *drv) +{ + ktime_t calltime, rettime; + int ret; + + calltime = ktime_get(); + ret = really_probe(dev, drv); + rettime = ktime_get(); + /* + * Don't change this to pr_debug() because that requires + * CONFIG_DYNAMIC_DEBUG and we want a simple 'initcall_debug' on the + * kernel commandline to print this all the time at the debug level. + */ + printk(KERN_DEBUG "probe of %s returned %d after %lld usecs\n", + dev_name(dev), ret, ktime_us_delta(rettime, calltime)); + return ret; +} + +/** + * driver_probe_done + * Determine if the probe sequence is finished or not. + * + * Should somehow figure out how to use a semaphore, not an atomic variable... + */ +int driver_probe_done(void) +{ + int local_probe_count = atomic_read(&probe_count); + + pr_debug("%s: probe_count = %d\n", __func__, local_probe_count); + if (local_probe_count) + return -EBUSY; + return 0; +} + +/** + * wait_for_device_probe + * Wait for device probing to be completed. + */ +void wait_for_device_probe(void) +{ + /* wait for the deferred probe workqueue to finish */ + flush_work(&deferred_probe_work); + + /* wait for the known devices to complete their probing */ + wait_event(probe_waitqueue, atomic_read(&probe_count) == 0); + async_synchronize_full(); +} +EXPORT_SYMBOL_GPL(wait_for_device_probe); + +/** + * driver_probe_device - attempt to bind device & driver together + * @drv: driver to bind a device to + * @dev: device to try to bind to the driver + * + * This function returns -ENODEV if the device is not registered, + * 1 if the device is bound successfully and 0 otherwise. + * + * This function must be called with @dev lock held. When called for a + * USB interface, @dev->parent lock must be held as well. + * + * If the device has a parent, runtime-resume the parent before driver probing. + */ +int driver_probe_device(struct device_driver *drv, struct device *dev) +{ + int ret = 0; + + if (!device_is_registered(dev)) + return -ENODEV; + + pr_debug("bus: '%s': %s: matched device %s with driver %s\n", + drv->bus->name, __func__, dev_name(dev), drv->name); + + pm_runtime_get_suppliers(dev); + if (dev->parent) + pm_runtime_get_sync(dev->parent); + + pm_runtime_barrier(dev); + if (initcall_debug) + ret = really_probe_debug(dev, drv); + else + ret = really_probe(dev, drv); + pm_request_idle(dev); + + if (dev->parent) + pm_runtime_put(dev->parent); + + pm_runtime_put_suppliers(dev); + return ret; +} + +static inline bool cmdline_requested_async_probing(const char *drv_name) +{ + return parse_option_str(async_probe_drv_names, drv_name); +} + +/* The option format is "driver_async_probe=drv_name1,drv_name2,..." */ +static int __init save_async_options(char *buf) +{ + if (strlen(buf) >= ASYNC_DRV_NAMES_MAX_LEN) + pr_warn("Too long list of driver names for 'driver_async_probe'!\n"); + + strlcpy(async_probe_drv_names, buf, ASYNC_DRV_NAMES_MAX_LEN); + return 1; +} +__setup("driver_async_probe=", save_async_options); + +bool driver_allows_async_probing(struct device_driver *drv) +{ + switch (drv->probe_type) { + case PROBE_PREFER_ASYNCHRONOUS: + return true; + + case PROBE_FORCE_SYNCHRONOUS: + return false; + + default: + if (cmdline_requested_async_probing(drv->name)) + return true; + + if (module_requested_async_probing(drv->owner)) + return true; + + return false; + } +} + +struct device_attach_data { + struct device *dev; + + /* + * Indicates whether we are are considering asynchronous probing or + * not. Only initial binding after device or driver registration + * (including deferral processing) may be done asynchronously, the + * rest is always synchronous, as we expect it is being done by + * request from userspace. + */ + bool check_async; + + /* + * Indicates if we are binding synchronous or asynchronous drivers. + * When asynchronous probing is enabled we'll execute 2 passes + * over drivers: first pass doing synchronous probing and second + * doing asynchronous probing (if synchronous did not succeed - + * most likely because there was no driver requiring synchronous + * probing - and we found asynchronous driver during first pass). + * The 2 passes are done because we can't shoot asynchronous + * probe for given device and driver from bus_for_each_drv() since + * driver pointer is not guaranteed to stay valid once + * bus_for_each_drv() iterates to the next driver on the bus. + */ + bool want_async; + + /* + * We'll set have_async to 'true' if, while scanning for matching + * driver, we'll encounter one that requests asynchronous probing. + */ + bool have_async; +}; + +static int __device_attach_driver(struct device_driver *drv, void *_data) +{ + struct device_attach_data *data = _data; + struct device *dev = data->dev; + bool async_allowed; + int ret; + + ret = driver_match_device(drv, dev); + if (ret == 0) { + /* no match */ + return 0; + } else if (ret == -EPROBE_DEFER) { + dev_dbg(dev, "Device match requests probe deferral\n"); + driver_deferred_probe_add(dev); + /* + * Device can't match with a driver right now, so don't attempt + * to match or bind with other drivers on the bus. + */ + return ret; + } else if (ret < 0) { + dev_dbg(dev, "Bus failed to match device: %d\n", ret); + return ret; + } /* ret > 0 means positive match */ + + async_allowed = driver_allows_async_probing(drv); + + if (async_allowed) + data->have_async = true; + + if (data->check_async && async_allowed != data->want_async) + return 0; + + return driver_probe_device(drv, dev); +} + +static void __device_attach_async_helper(void *_dev, async_cookie_t cookie) +{ + struct device *dev = _dev; + struct device_attach_data data = { + .dev = dev, + .check_async = true, + .want_async = true, + }; + + device_lock(dev); + + /* + * Check if device has already been removed or claimed. This may + * happen with driver loading, device discovery/registration, + * and deferred probe processing happens all at once with + * multiple threads. + */ + if (dev->p->dead || dev->driver) + goto out_unlock; + + if (dev->parent) + pm_runtime_get_sync(dev->parent); + + bus_for_each_drv(dev->bus, NULL, &data, __device_attach_driver); + dev_dbg(dev, "async probe completed\n"); + + pm_request_idle(dev); + + if (dev->parent) + pm_runtime_put(dev->parent); +out_unlock: + device_unlock(dev); + + put_device(dev); +} + +static int __device_attach(struct device *dev, bool allow_async) +{ + int ret = 0; + bool async = false; + + device_lock(dev); + if (dev->p->dead) { + goto out_unlock; + } else if (dev->driver) { + if (device_is_bound(dev)) { + ret = 1; + goto out_unlock; + } + ret = device_bind_driver(dev); + if (ret == 0) + ret = 1; + else { + dev->driver = NULL; + ret = 0; + } + } else { + struct device_attach_data data = { + .dev = dev, + .check_async = allow_async, + .want_async = false, + }; + + if (dev->parent) + pm_runtime_get_sync(dev->parent); + + ret = bus_for_each_drv(dev->bus, NULL, &data, + __device_attach_driver); + if (!ret && allow_async && data.have_async) { + /* + * If we could not find appropriate driver + * synchronously and we are allowed to do + * async probes and there are drivers that + * want to probe asynchronously, we'll + * try them. + */ + dev_dbg(dev, "scheduling asynchronous probe\n"); + get_device(dev); + async = true; + } else { + pm_request_idle(dev); + } + + if (dev->parent) + pm_runtime_put(dev->parent); + } +out_unlock: + device_unlock(dev); + if (async) + async_schedule_dev(__device_attach_async_helper, dev); + return ret; +} + +/** + * device_attach - try to attach device to a driver. + * @dev: device. + * + * Walk the list of drivers that the bus has and call + * driver_probe_device() for each pair. If a compatible + * pair is found, break out and return. + * + * Returns 1 if the device was bound to a driver; + * 0 if no matching driver was found; + * -ENODEV if the device is not registered. + * + * When called for a USB interface, @dev->parent lock must be held. + */ +int device_attach(struct device *dev) +{ + return __device_attach(dev, false); +} +EXPORT_SYMBOL_GPL(device_attach); + +void device_initial_probe(struct device *dev) +{ + __device_attach(dev, true); +} + +/* + * __device_driver_lock - acquire locks needed to manipulate dev->drv + * @dev: Device we will update driver info for + * @parent: Parent device. Needed if the bus requires parent lock + * + * This function will take the required locks for manipulating dev->drv. + * Normally this will just be the @dev lock, but when called for a USB + * interface, @parent lock will be held as well. + */ +static void __device_driver_lock(struct device *dev, struct device *parent) +{ + if (parent && dev->bus->need_parent_lock) + device_lock(parent); + device_lock(dev); +} + +/* + * __device_driver_unlock - release locks needed to manipulate dev->drv + * @dev: Device we will update driver info for + * @parent: Parent device. Needed if the bus requires parent lock + * + * This function will release the required locks for manipulating dev->drv. + * Normally this will just be the the @dev lock, but when called for a + * USB interface, @parent lock will be released as well. + */ +static void __device_driver_unlock(struct device *dev, struct device *parent) +{ + device_unlock(dev); + if (parent && dev->bus->need_parent_lock) + device_unlock(parent); +} + +/** + * device_driver_attach - attach a specific driver to a specific device + * @drv: Driver to attach + * @dev: Device to attach it to + * + * Manually attach driver to a device. Will acquire both @dev lock and + * @dev->parent lock if needed. + */ +int device_driver_attach(struct device_driver *drv, struct device *dev) +{ + int ret = 0; + + __device_driver_lock(dev, dev->parent); + + /* + * If device has been removed or someone has already successfully + * bound a driver before us just skip the driver probe call. + */ + if (!dev->p->dead && !dev->driver) + ret = driver_probe_device(drv, dev); + + __device_driver_unlock(dev, dev->parent); + + return ret; +} + +static void __driver_attach_async_helper(void *_dev, async_cookie_t cookie) +{ + struct device *dev = _dev; + struct device_driver *drv; + int ret = 0; + + __device_driver_lock(dev, dev->parent); + + drv = dev->p->async_driver; + + /* + * If device has been removed or someone has already successfully + * bound a driver before us just skip the driver probe call. + */ + if (!dev->p->dead && !dev->driver) + ret = driver_probe_device(drv, dev); + + __device_driver_unlock(dev, dev->parent); + + dev_dbg(dev, "driver %s async attach completed: %d\n", drv->name, ret); + + put_device(dev); +} + +static int __driver_attach(struct device *dev, void *data) +{ + struct device_driver *drv = data; + bool async = false; + int ret; + + /* + * Lock device and try to bind to it. We drop the error + * here and always return 0, because we need to keep trying + * to bind to devices and some drivers will return an error + * simply if it didn't support the device. + * + * driver_probe_device() will spit a warning if there + * is an error. + */ + + ret = driver_match_device(drv, dev); + if (ret == 0) { + /* no match */ + return 0; + } else if (ret == -EPROBE_DEFER) { + dev_dbg(dev, "Device match requests probe deferral\n"); + driver_deferred_probe_add(dev); + /* + * Driver could not match with device, but may match with + * another device on the bus. + */ + return 0; + } else if (ret < 0) { + dev_dbg(dev, "Bus failed to match device: %d\n", ret); + /* + * Driver could not match with device, but may match with + * another device on the bus. + */ + return 0; + } /* ret > 0 means positive match */ + + if (driver_allows_async_probing(drv)) { + /* + * Instead of probing the device synchronously we will + * probe it asynchronously to allow for more parallelism. + * + * We only take the device lock here in order to guarantee + * that the dev->driver and async_driver fields are protected + */ + dev_dbg(dev, "probing driver %s asynchronously\n", drv->name); + device_lock(dev); + if (!dev->driver) { + get_device(dev); + dev->p->async_driver = drv; + async = true; + } + device_unlock(dev); + if (async) + async_schedule_dev(__driver_attach_async_helper, dev); + return 0; + } + + device_driver_attach(drv, dev); + + return 0; +} + +/** + * driver_attach - try to bind driver to devices. + * @drv: driver. + * + * Walk the list of devices that the bus has on it and try to + * match the driver with each one. If driver_probe_device() + * returns 0 and the @dev->driver is set, we've found a + * compatible pair. + */ +int driver_attach(struct device_driver *drv) +{ + return bus_for_each_dev(drv->bus, NULL, drv, __driver_attach); +} +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, struct device *parent) +{ + struct device_driver *drv; + + drv = dev->driver; + if (drv) { + pm_runtime_get_sync(dev); + + while (device_links_busy(dev)) { + __device_driver_unlock(dev, parent); + + device_links_unbind_consumers(dev); + + __device_driver_lock(dev, parent); + /* + * 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) { + pm_runtime_put(dev); + return; + } + } + + driver_sysfs_remove(dev); + + if (dev->bus) + blocking_notifier_call_chain(&dev->bus->p->bus_notifier, + BUS_NOTIFY_UNBIND_DRIVER, + dev); + + pm_runtime_put_sync(dev); + + device_remove_file(dev, &dev_attr_state_synced); + device_remove_groups(dev, drv->dev_groups); + + if (dev->bus && dev->bus->remove) + dev->bus->remove(dev); + else if (drv->remove) + drv->remove(dev); + + devres_release_all(dev); + arch_teardown_dma_ops(dev); + kfree(dev->dma_range_map); + dev->dma_range_map = NULL; + dev->driver = NULL; + dev_set_drvdata(dev, NULL); + if (dev->pm_domain && dev->pm_domain->dismiss) + dev->pm_domain->dismiss(dev); + pm_runtime_reinit(dev); + dev_pm_set_driver_flags(dev, 0); + + device_links_driver_cleanup(dev); + + klist_remove(&dev->p->knode_driver); + device_pm_check_callbacks(dev); + if (dev->bus) + blocking_notifier_call_chain(&dev->bus->p->bus_notifier, + BUS_NOTIFY_UNBOUND_DRIVER, + dev); + + kobject_uevent(&dev->kobj, KOBJ_UNBIND); + } +} + +void device_release_driver_internal(struct device *dev, + struct device_driver *drv, + struct device *parent) +{ + __device_driver_lock(dev, parent); + + if (!drv || drv == dev->driver) + __device_release_driver(dev, parent); + + __device_driver_unlock(dev, parent); +} + +/** + * device_release_driver - manually detach device from driver. + * @dev: device. + * + * 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) +{ + /* + * If anyone calls device_release_driver() recursively from + * within their ->remove callback for the same device, they + * will deadlock right here. + */ + device_release_driver_internal(dev, NULL, NULL); +} +EXPORT_SYMBOL_GPL(device_release_driver); + +/** + * device_driver_detach - detach driver from a specific device + * @dev: device to detach driver from + * + * Detach driver from device. Will acquire both @dev lock and @dev->parent + * lock if needed. + */ +void device_driver_detach(struct device *dev) +{ + device_release_driver_internal(dev, NULL, dev->parent); +} + +/** + * driver_detach - detach driver from all devices it controls. + * @drv: driver. + */ +void driver_detach(struct device_driver *drv) +{ + struct device_private *dev_prv; + struct device *dev; + + if (driver_allows_async_probing(drv)) + async_synchronize_full(); + + for (;;) { + spin_lock(&drv->p->klist_devices.k_lock); + if (list_empty(&drv->p->klist_devices.k_list)) { + spin_unlock(&drv->p->klist_devices.k_lock); + break; + } + dev_prv = list_last_entry(&drv->p->klist_devices.k_list, + struct device_private, + knode_driver.n_node); + dev = dev_prv->device; + get_device(dev); + spin_unlock(&drv->p->klist_devices.k_lock); + device_release_driver_internal(dev, drv, dev->parent); + put_device(dev); + } +} |