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[PATCH] Driver Core: driver model doc update

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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>
This commit is contained in:
David Brownell 2005-05-16 17:19:55 -07:00 committed by Greg Kroah-Hartman
parent 4b45099b75
commit 4109aca06c
2 changed files with 31 additions and 24 deletions
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8
Documentation/driver-model/device.txt
View file

@ -76,6 +76,14 @@ driver_data: Driver-specific data.
platform_data: Platform data specific to the device.
Example: for devices on custom boards, as typical of embedded
and SOC based hardware, Linux often uses platform_data to point
to board-specific structures describing devices and how they
are wired. That can include what ports are available, chip
variants, which GPIO pins act in what additional roles, and so
on. This shrinks the "Board Support Packages" (BSPs) and
minimizes board-specific #ifdefs in drivers.
current_state: Current power state of the device.
saved_state: Pointer to saved state of the device. This is usable by

47
Documentation/driver-model/driver.txt
View file

@ -5,21 +5,17 @@ struct device_driver {
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 @@ being converted completely to the new model.
static struct device_driver eepro100_driver = {
.name = "eepro100",
.bus = &pci_bus_type,
.devclass = &ethernet_devclass, /* when it's implemented */
.probe = eepro100_probe,
.remove = eepro100_remove,
@ -85,7 +80,6 @@ static struct pci_driver eepro100_driver = {
.driver = {
.name = "eepro100",
.bus = &pci_bus_type,
.devclass = &ethernet_devclass, /* when it's implemented */
.probe = eepro100_probe,
.remove = eepro100_remove,
.suspend = eepro100_suspend,
@ -166,27 +160,32 @@ Callbacks
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