[PATCH] driver core: add bus_find_device & driver_find_device functions

Add bus_find_device() and driver_find_device() which allow searching for a
device in the bus's resp. the driver's klist and obtain a reference on it.

Signed-off-by: Cornelia Huck <cohuck@de.ibm.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

2 files changed, 69 insertions, 0 deletions

diff --git a/drivers/base/bus.c b/drivers/base/bus.c
index c3fac7fd555e..2c64b792d074 100644
--- a/drivers/base/bus.c
+++ b/drivers/base/bus.c
@@ -177,6 +177,39 @@ int bus_for_each_dev(struct bus_type * bus, struct device * start,
 	return error;
 }
 
+/**
+ * bus_find_device - device iterator for locating a particular device.
+ * @bus: bus type
+ * @start: Device to begin with
+ * @data: Data to pass to match function
+ * @match: Callback function to check device
+ *
+ * This is similar to the bus_for_each_dev() function above, but it
+ * returns a reference to a device that is 'found' for later use, as
+ * determined by the @match callback.
+ *
+ * The callback should return 0 if the device doesn't match and non-zero
+ * if it does.  If the callback returns non-zero, this function will
+ * return to the caller and not iterate over any more devices.
+ */
+struct device * bus_find_device(struct bus_type *bus,
+				struct device *start, void *data,
+				int (*match)(struct device *, void *))
+{
+	struct klist_iter i;
+	struct device *dev;
+
+	if (!bus)
+		return NULL;
+
+	klist_iter_init_node(&bus->klist_devices, &i,
+			     (start ? &start->knode_bus : NULL));
+	while ((dev = next_device(&i)))
+		if (match(dev, data) && get_device(dev))
+			break;
+	klist_iter_exit(&i);
+	return dev;
+}
 
 
 static struct device_driver * next_driver(struct klist_iter * i)
@@ -557,6 +590,7 @@ int __init buses_init(void)
 
 
 EXPORT_SYMBOL_GPL(bus_for_each_dev);
+EXPORT_SYMBOL_GPL(bus_find_device);
 EXPORT_SYMBOL_GPL(bus_for_each_drv);
 
 EXPORT_SYMBOL_GPL(bus_add_device);
diff --git a/drivers/base/driver.c b/drivers/base/driver.c
index 1b645886e9eb..291c5954a3af 100644
--- a/drivers/base/driver.c
+++ b/drivers/base/driver.c
@@ -56,6 +56,41 @@ EXPORT_SYMBOL_GPL(driver_for_each_device);
 
 
 /**
+ * driver_find_device - device iterator for locating a particular device.
+ * @driver: The device's driver
+ * @start: Device to begin with
+ * @data: Data to pass to match function
+ * @match: Callback function to check device
+ *
+ * This is similar to the driver_for_each_device() function above, but
+ * it returns a reference to a device that is 'found' for later use, as
+ * determined by the @match callback.
+ *
+ * The callback should return 0 if the device doesn't match and non-zero
+ * if it does.  If the callback returns non-zero, this function will
+ * return to the caller and not iterate over any more devices.
+ */
+struct device * driver_find_device(struct device_driver *drv,
+				   struct device * start, void * data,
+				   int (*match)(struct device *, void *))
+{
+	struct klist_iter i;
+	struct device *dev;
+
+	if (!drv)
+		return NULL;
+
+	klist_iter_init_node(&drv->klist_devices, &i,
+			     (start ? &start->knode_driver : NULL));
+	while ((dev = next_device(&i)))
+		if (match(dev, data) && get_device(dev))
+			break;
+	klist_iter_exit(&i);
+	return dev;
+}
+EXPORT_SYMBOL_GPL(driver_find_device);
+
+/**
  *	driver_create_file - create sysfs file for driver.
  *	@drv:	driver.
  *	@attr:	driver attribute descriptor.