[PATCH 04/46] Driver core: udev triggered device-driver binding

Greg Kroah-Hartman
2007-04-27T20:29:59Z

From: Kay Sievers <kay.sievers@vrfy.org>

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: Greg Kroah-Hartman <gregkh@suse.de>
---
drivers/base/bus.c | 84 ++++++++++++++++++++++++++++++++++++++++++++---
include/linux/device.h | 34 +++++++++++--------
2 files changed, 97 insertions(+), 21 deletions(-)

diff --git a/drivers/base/bus.c b/drivers/base/bus.c
index 253868e..9df2e6d 100644
--- a/drivers/base/bus.c
+++ b/drivers/base/bus.c
@@ -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)
@@ -425,7 +454,8 @@ int bus_attach_device(struct device * dev)

if (bus) {
dev->is_registered = 1;
- ret = device_attach(dev);
+ if (bus->drivers_autoprobe)
+ ret = device_attach(dev);
if (ret >= 0) {
klist_add_tail(&dev->knode_bus, &bus->klist_devices);
ret = 0;
@@ -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;

- error = driver_attach(drv);
- if (error)
- goto out_unregister;
+ 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);
diff --git a/include/linux/device.h b/include/linux/device.h
index de0e73e..9d54fe1 100644
--- a/include/linux/device.h
+++ b/include/linux/device.h
@@ -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;
--
1.5.1.2