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Commit b8c5cec2 authored by Kay Sievers's avatar Kay Sievers Committed by Greg Kroah-Hartman
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Driver core: udev triggered device-<>driver binding 



We get two per-bus sysfs files:
  ls-l /sys/subsystem/usb
  drwxr-xr-x 2 root root    0 2007-02-16 16:42 devices
  drwxr-xr-x 7 root root    0 2007-02-16 14:55 drivers
  -rw-r--r-- 1 root root 4096 2007-02-16 16:42 drivers_autoprobe
  --w------- 1 root root 4096 2007-02-16 16:42 drivers_probe

The flag "drivers_autoprobe" controls the behavior of the bus to bind
devices by default, or just initialize the device and leave it alone.

The command "drivers_probe" accepts a bus_id and the bus tries to bind a
driver to this device.

Systems who want to control the driver binding with udev, switch off the
bus initiated probing:
  echo 0 > /sys/subsystem/usb/drivers_autoprobe
  echo 0 > /sys/subsystem/pcmcia/drivers_autoprobe
  ...

and initiate the probing with udev rules like:
  ACTION=="add", SUBSYSTEM=="usb", ATTR{subsystem/drivers_probe}="$kernel"
  ACTION=="add", SUBSYSTEM=="pcmcia", ATTR{subsystem/drivers_probe}="$kernel"
  ...

Custom driver binding can happen in earlier rules by something like:
  ACTION=="add", SUBSYSTEM=="usb", \
  ATTRS{idVendor}=="1234", ATTRS{idProduct}=="5678" \
  ATTR{subsystem/drivers/<custom-driver>/bind}="$kernel"

This is intended to solve the modprobe.conf mess with "install-rules", custom
bind/unbind-scripts and all the weird things people invented over the years.
It should also provide the functionality "libusual" was supposed to do.

With udev, one can just write a udev rule to drive all USB-disks at the
third port of USB-hub by the "ub" driver, and everything else by
usb-storage. One can also instruct udev to bind different wireless
drivers to identical cards - just selected by the pcmcia slot-number, and
whatever ...

To use the mentioned rules, it needs udev version 106, to be able to
write ATTR{}="$kernel" to sysfs files.

Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@suse.de>
parent a456b702

drivers/base/bus.c

+78 −6
Original line number Diff line number Diff line
@@ -27,6 +27,9 @@ 
#define to_driver(obj) container_of(obj, struct device_driver, kobj)





static int __must_check bus_rescan_devices_helper(struct device *dev,

						void *data);



static ssize_t

drv_attr_show(struct kobject * kobj, struct attribute * attr, char * buf)

{
@@ -133,7 +136,6 @@ static decl_subsys(bus, &ktype_bus, NULL); 




#ifdef CONFIG_HOTPLUG



/* Manually detach a device from its associated driver. */

static int driver_helper(struct device *dev, void *data)

{
@@ -199,6 +201,33 @@ static ssize_t driver_bind(struct device_driver *drv, 
}

static DRIVER_ATTR(bind, S_IWUSR, NULL, driver_bind);



static ssize_t show_drivers_autoprobe(struct bus_type *bus, char *buf)

{

	return sprintf(buf, "%d\n", bus->drivers_autoprobe);

}



static ssize_t store_drivers_autoprobe(struct bus_type *bus,

				       const char *buf, size_t count)

{

	if (buf[0] == '0')

		bus->drivers_autoprobe = 0;

	else

		bus->drivers_autoprobe = 1;

	return count;

}



static ssize_t store_drivers_probe(struct bus_type *bus,

				   const char *buf, size_t count)

{

	struct device *dev;



	dev = bus_find_device(bus, NULL, (void *)buf, driver_helper);

	if (!dev)

		return -ENODEV;

	if (bus_rescan_devices_helper(dev, NULL) != 0)

		return -EINVAL;

	return count;

}

#endif



static struct device * next_device(struct klist_iter * i)
@@ -425,6 +454,7 @@ int bus_attach_device(struct device * dev) 


	if (bus) {

		dev->is_registered = 1;

		if (bus->drivers_autoprobe)

			ret = device_attach(dev);

		if (ret >= 0) {

			klist_add_tail(&dev->knode_bus, &bus->klist_devices);
@@ -515,9 +545,41 @@ static void remove_bind_files(struct device_driver *drv) 
	driver_remove_file(drv, &driver_attr_bind);

	driver_remove_file(drv, &driver_attr_unbind);

}



static int add_probe_files(struct bus_type *bus)

{

	int retval;



	bus->drivers_probe_attr.attr.name = "drivers_probe";

	bus->drivers_probe_attr.attr.mode = S_IWUSR;

	bus->drivers_probe_attr.attr.owner = bus->owner;

	bus->drivers_probe_attr.store = store_drivers_probe;

	retval = bus_create_file(bus, &bus->drivers_probe_attr);

	if (retval)

		goto out;



	bus->drivers_autoprobe_attr.attr.name = "drivers_autoprobe";

	bus->drivers_autoprobe_attr.attr.mode = S_IWUSR | S_IRUGO;

	bus->drivers_autoprobe_attr.attr.owner = bus->owner;

	bus->drivers_autoprobe_attr.show = show_drivers_autoprobe;

	bus->drivers_autoprobe_attr.store = store_drivers_autoprobe;

	retval = bus_create_file(bus, &bus->drivers_autoprobe_attr);

	if (retval)

		bus_remove_file(bus, &bus->drivers_probe_attr);

out:

	return retval;

}



static void remove_probe_files(struct bus_type *bus)

{

	bus_remove_file(bus, &bus->drivers_autoprobe_attr);

	bus_remove_file(bus, &bus->drivers_probe_attr);

}

#else

static inline int add_bind_files(struct device_driver *drv) { return 0; }

static inline void remove_bind_files(struct device_driver *drv) {}

static inline int add_probe_files(struct bus_type *bus) { return 0; }

static inline void remove_probe_files(struct bus_type *bus) {}

#endif



/**
@@ -541,9 +603,11 @@ int bus_add_driver(struct device_driver *drv) 
	if ((error = kobject_register(&drv->kobj)))

		goto out_put_bus;



	if (drv->bus->drivers_autoprobe) {

		error = driver_attach(drv);

		if (error)

			goto out_unregister;

	}

	klist_add_tail(&drv->knode_bus, &bus->klist_drivers);

	module_add_driver(drv->owner, drv);
@@ -762,6 +826,12 @@ int bus_register(struct bus_type * bus) 


	klist_init(&bus->klist_devices, klist_devices_get, klist_devices_put);

	klist_init(&bus->klist_drivers, NULL, NULL);



	bus->drivers_autoprobe = 1;

	retval = add_probe_files(bus);

	if (retval)

		goto bus_probe_files_fail;



	retval = bus_add_attrs(bus);

	if (retval)

		goto bus_attrs_fail;
@@ -770,6 +840,8 @@ int bus_register(struct bus_type * bus) 
	return 0;



bus_attrs_fail:

	remove_probe_files(bus);

bus_probe_files_fail:

	kset_unregister(&bus->drivers);

bus_drivers_fail:

	kset_unregister(&bus->devices);
@@ -779,7 +851,6 @@ out: 
	return retval;

}





/**

 *	bus_unregister - remove a bus from the system

 *	@bus:	bus.
@@ -791,6 +862,7 @@ void bus_unregister(struct bus_type * bus) 
{

	pr_debug("bus %s: unregistering\n", bus->name);

	bus_remove_attrs(bus);

	remove_probe_files(bus);

	kset_unregister(&bus->drivers);

	kset_unregister(&bus->devices);

	subsystem_unregister(&bus->subsys);

include/linux/device.h

+19 −15
Original line number Diff line number Diff line
@@ -34,9 +34,24 @@ struct device; 
struct device_driver;

struct class;

struct class_device;

struct bus_type;



struct bus_attribute {

	struct attribute	attr;

	ssize_t (*show)(struct bus_type *, char * buf);

	ssize_t (*store)(struct bus_type *, const char * buf, size_t count);

};



#define BUS_ATTR(_name,_mode,_show,_store)	\

struct bus_attribute bus_attr_##_name = __ATTR(_name,_mode,_show,_store)



extern int __must_check bus_create_file(struct bus_type *,

					struct bus_attribute *);

extern void bus_remove_file(struct bus_type *, struct bus_attribute *);



struct bus_type {

	const char		* name;

	struct module		* owner;



	struct subsystem	subsys;

	struct kset		drivers;
@@ -49,6 +64,8 @@ struct bus_type { 
	struct bus_attribute	* bus_attrs;

	struct device_attribute	* dev_attrs;

	struct driver_attribute	* drv_attrs;

	struct bus_attribute drivers_autoprobe_attr;

	struct bus_attribute drivers_probe_attr;



	int		(*match)(struct device * dev, struct device_driver * drv);

	int		(*uevent)(struct device *dev, char **envp,
@@ -61,6 +78,8 @@ struct bus_type { 
	int (*suspend_late)(struct device * dev, pm_message_t state);

	int (*resume_early)(struct device * dev);

	int (*resume)(struct device * dev);



	unsigned int drivers_autoprobe:1;

};



extern int __must_check bus_register(struct bus_type * bus);
@@ -102,21 +121,6 @@ extern int bus_unregister_notifier(struct bus_type *bus, 
#define BUS_NOTIFY_UNBIND_DRIVER	0x00000004 /* driver about to be

						      unbound */



/* sysfs interface for exporting bus attributes */



struct bus_attribute {

	struct attribute	attr;

	ssize_t (*show)(struct bus_type *, char * buf);

	ssize_t (*store)(struct bus_type *, const char * buf, size_t count);

};



#define BUS_ATTR(_name,_mode,_show,_store)	\

struct bus_attribute bus_attr_##_name = __ATTR(_name,_mode,_show,_store)



extern int __must_check bus_create_file(struct bus_type *,

					struct bus_attribute *);

extern void bus_remove_file(struct bus_type *, struct bus_attribute *);



struct device_driver {

	const char		* name;

	struct bus_type		* bus;