[PATCH] Driver Core: driver model doc update
This updates some driver data documentation:
- removes references to some fields that haven't been there for a
long time now, e.g. pre-kobject or even older;
- giving more information about the probe() method;
- adding an example of how platform_data is used
Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
diff --git a/Documentation/driver-model/driver.txt b/Documentation/driver-model/driver.txt
index 6031a68..fabaca1 100644
--- a/Documentation/driver-model/driver.txt
+++ b/Documentation/driver-model/driver.txt
@@ -5,21 +5,17 @@
char * name;
struct bus_type * bus;
- rwlock_t lock;
- atomic_t refcount;
-
- list_t bus_list;
+ struct completion unloaded;
+ struct kobject kobj;
list_t devices;
- struct driver_dir_entry dir;
+ struct module *owner;
int (*probe) (struct device * dev);
int (*remove) (struct device * dev);
int (*suspend) (struct device * dev, pm_message_t state, u32 level);
int (*resume) (struct device * dev, u32 level);
-
- void (*release) (struct device_driver * drv);
};
@@ -51,7 +47,6 @@
static struct device_driver eepro100_driver = {
.name = "eepro100",
.bus = &pci_bus_type,
- .devclass = ðernet_devclass, /* when it's implemented */
.probe = eepro100_probe,
.remove = eepro100_remove,
@@ -85,7 +80,6 @@
.driver = {
.name = "eepro100",
.bus = &pci_bus_type,
- .devclass = ðernet_devclass, /* when it's implemented */
.probe = eepro100_probe,
.remove = eepro100_remove,
.suspend = eepro100_suspend,
@@ -166,27 +160,32 @@
int (*probe) (struct device * dev);
-probe is called to verify the existence of a certain type of
-hardware. This is called during the driver binding process, after the
-bus has verified that the device ID of a device matches one of the
-device IDs supported by the driver.
+The probe() entry is called in task context, with the bus's rwsem locked
+and the driver partially bound to the device. Drivers commonly use
+container_of() to convert "dev" to a bus-specific type, both in probe()
+and other routines. That type often provides device resource data, such
+as pci_dev.resource[] or platform_device.resources, which is used in
+addition to dev->platform_data to initialize the driver.
-This callback only verifies that there actually is supported hardware
-present. It may allocate a driver-specific structure, but it should
-not do any initialization of the hardware itself. The device-specific
-structure may be stored in the device's driver_data field.
+This callback holds the driver-specific logic to bind the driver to a
+given device. That includes verifying that the device is present, that
+it's a version the driver can handle, that driver data structures can
+be allocated and initialized, and that any hardware can be initialized.
+Drivers often store a pointer to their state with dev_set_drvdata().
+When the driver has successfully bound itself to that device, then probe()
+returns zero and the driver model code will finish its part of binding
+the driver to that device.
- int (*init) (struct device * dev);
-
-init is called during the binding stage. It is called after probe has
-successfully returned and the device has been registered with its
-class. It is responsible for initializing the hardware.
+A driver's probe() may return a negative errno value to indicate that
+the driver did not bind to this device, in which case it should have
+released all reasources it allocated.
int (*remove) (struct device * dev);
-remove is called to dissociate a driver with a device. This may be
+remove is called to unbind a driver from a device. This may be
called if a device is physically removed from the system, if the
-driver module is being unloaded, or during a reboot sequence.
+driver module is being unloaded, during a reboot sequence, or
+in other cases.
It is up to the driver to determine if the device is present or
not. It should free any resources allocated specifically for the