271 lines
6.8 KiB
C
271 lines
6.8 KiB
C
/*
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* drivers/base/dd.c - The core device/driver interactions.
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*
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* This file contains the (sometimes tricky) code that controls the
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* interactions between devices and drivers, which primarily includes
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* driver binding and unbinding.
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*
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* All of this code used to exist in drivers/base/bus.c, but was
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* relocated to here in the name of compartmentalization (since it wasn't
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* strictly code just for the 'struct bus_type'.
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*
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* Copyright (c) 2002-5 Patrick Mochel
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* Copyright (c) 2002-3 Open Source Development Labs
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*
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* This file is released under the GPLv2
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*/
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#include <linux/device.h>
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#include <linux/module.h>
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#include "base.h"
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#include "power/power.h"
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#define to_drv(node) container_of(node, struct device_driver, kobj.entry)
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/**
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* device_bind_driver - bind a driver to one device.
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* @dev: device.
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*
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* Allow manual attachment of a driver to a device.
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* Caller must have already set @dev->driver.
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*
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* Note that this does not modify the bus reference count
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* nor take the bus's rwsem. Please verify those are accounted
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* for before calling this. (It is ok to call with no other effort
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* from a driver's probe() method.)
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*
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* This function must be called with @dev->sem held.
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*/
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void device_bind_driver(struct device * dev)
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{
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if (klist_node_attached(&dev->knode_driver))
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return;
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pr_debug("bound device '%s' to driver '%s'\n",
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dev->bus_id, dev->driver->name);
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klist_add_tail(&dev->knode_driver, &dev->driver->klist_devices);
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sysfs_create_link(&dev->driver->kobj, &dev->kobj,
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kobject_name(&dev->kobj));
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sysfs_create_link(&dev->kobj, &dev->driver->kobj, "driver");
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}
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/**
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* driver_probe_device - attempt to bind device & driver.
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* @drv: driver.
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* @dev: device.
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*
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* First, we call the bus's match function, if one present, which
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* should compare the device IDs the driver supports with the
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* device IDs of the device. Note we don't do this ourselves
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* because we don't know the format of the ID structures, nor what
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* is to be considered a match and what is not.
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*
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* This function returns 1 if a match is found, an error if one
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* occurs (that is not -ENODEV or -ENXIO), and 0 otherwise.
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*
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* This function must be called with @dev->sem held. When called
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* for a USB interface, @dev->parent->sem must be held as well.
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*/
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int driver_probe_device(struct device_driver * drv, struct device * dev)
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{
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int ret = 0;
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if (drv->bus->match && !drv->bus->match(dev, drv))
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goto Done;
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pr_debug("%s: Matched Device %s with Driver %s\n",
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drv->bus->name, dev->bus_id, drv->name);
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dev->driver = drv;
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if (dev->bus->probe) {
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ret = dev->bus->probe(dev);
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if (ret) {
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dev->driver = NULL;
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goto ProbeFailed;
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}
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} else if (drv->probe) {
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ret = drv->probe(dev);
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if (ret) {
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dev->driver = NULL;
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goto ProbeFailed;
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}
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}
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device_bind_driver(dev);
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ret = 1;
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pr_debug("%s: Bound Device %s to Driver %s\n",
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drv->bus->name, dev->bus_id, drv->name);
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goto Done;
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ProbeFailed:
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if (ret == -ENODEV || ret == -ENXIO) {
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/* Driver matched, but didn't support device
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* or device not found.
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* Not an error; keep going.
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*/
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ret = 0;
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} else {
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/* driver matched but the probe failed */
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printk(KERN_WARNING
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"%s: probe of %s failed with error %d\n",
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drv->name, dev->bus_id, ret);
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}
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Done:
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return ret;
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}
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static int __device_attach(struct device_driver * drv, void * data)
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{
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struct device * dev = data;
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return driver_probe_device(drv, dev);
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}
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/**
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* device_attach - try to attach device to a driver.
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* @dev: device.
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*
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* Walk the list of drivers that the bus has and call
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* driver_probe_device() for each pair. If a compatible
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* pair is found, break out and return.
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*
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* Returns 1 if the device was bound to a driver;
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* 0 if no matching device was found; error code otherwise.
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*
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* When called for a USB interface, @dev->parent->sem must be held.
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*/
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int device_attach(struct device * dev)
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{
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int ret = 0;
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down(&dev->sem);
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if (dev->driver) {
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device_bind_driver(dev);
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ret = 1;
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} else
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ret = bus_for_each_drv(dev->bus, NULL, dev, __device_attach);
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up(&dev->sem);
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return ret;
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}
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static int __driver_attach(struct device * dev, void * data)
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{
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struct device_driver * drv = data;
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/*
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* Lock device and try to bind to it. We drop the error
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* here and always return 0, because we need to keep trying
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* to bind to devices and some drivers will return an error
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* simply if it didn't support the device.
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*
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* driver_probe_device() will spit a warning if there
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* is an error.
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*/
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if (dev->parent) /* Needed for USB */
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down(&dev->parent->sem);
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down(&dev->sem);
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if (!dev->driver)
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driver_probe_device(drv, dev);
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up(&dev->sem);
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if (dev->parent)
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up(&dev->parent->sem);
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return 0;
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}
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/**
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* driver_attach - try to bind driver to devices.
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* @drv: driver.
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*
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* Walk the list of devices that the bus has on it and try to
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* match the driver with each one. If driver_probe_device()
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* returns 0 and the @dev->driver is set, we've found a
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* compatible pair.
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*/
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void driver_attach(struct device_driver * drv)
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{
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bus_for_each_dev(drv->bus, NULL, drv, __driver_attach);
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}
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/**
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* device_release_driver - manually detach device from driver.
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* @dev: device.
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*
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* Manually detach device from driver.
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*
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* __device_release_driver() must be called with @dev->sem held.
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* When called for a USB interface, @dev->parent->sem must be held
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* as well.
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*/
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static void __device_release_driver(struct device * dev)
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{
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struct device_driver * drv;
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drv = dev->driver;
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if (drv) {
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get_driver(drv);
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sysfs_remove_link(&drv->kobj, kobject_name(&dev->kobj));
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sysfs_remove_link(&dev->kobj, "driver");
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klist_remove(&dev->knode_driver);
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if (dev->bus->remove)
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dev->bus->remove(dev);
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else if (drv->remove)
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drv->remove(dev);
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dev->driver = NULL;
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put_driver(drv);
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}
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}
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void device_release_driver(struct device * dev)
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{
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/*
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* If anyone calls device_release_driver() recursively from
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* within their ->remove callback for the same device, they
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* will deadlock right here.
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*/
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down(&dev->sem);
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__device_release_driver(dev);
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up(&dev->sem);
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}
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/**
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* driver_detach - detach driver from all devices it controls.
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* @drv: driver.
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*/
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void driver_detach(struct device_driver * drv)
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{
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struct device * dev;
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for (;;) {
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spin_lock(&drv->klist_devices.k_lock);
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if (list_empty(&drv->klist_devices.k_list)) {
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spin_unlock(&drv->klist_devices.k_lock);
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break;
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}
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dev = list_entry(drv->klist_devices.k_list.prev,
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struct device, knode_driver.n_node);
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get_device(dev);
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spin_unlock(&drv->klist_devices.k_lock);
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if (dev->parent) /* Needed for USB */
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down(&dev->parent->sem);
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down(&dev->sem);
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if (dev->driver == drv)
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__device_release_driver(dev);
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up(&dev->sem);
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if (dev->parent)
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up(&dev->parent->sem);
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put_device(dev);
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}
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}
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EXPORT_SYMBOL_GPL(device_bind_driver);
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EXPORT_SYMBOL_GPL(device_release_driver);
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EXPORT_SYMBOL_GPL(device_attach);
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EXPORT_SYMBOL_GPL(driver_attach);
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