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[Documentation]: Update probing info in sbus_drivers.txt

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Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
David S. Miller 2006-06-23 22:12:39 -07:00
parent 3d4253d9af
commit 9eccf1b312
1 changed files with 65 additions and 30 deletions
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95
Documentation/sparc/sbus_drivers.txt
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@ -25,42 +25,84 @@ the bits necessary to run your device. The most commonly
used members of this structure, and their typical usage,
will be detailed below.
Here is how probing is performed by an SBUS driver
under Linux:
Here is a piece of skeleton code for perofming a device
probe in an SBUS driverunder Linux:
static void init_one_mydevice(struct sbus_dev *sdev)
static int __devinit mydevice_probe_one(struct sbus_dev *sdev)
{
struct mysdevice *mp = kzalloc(sizeof(*mp), GFP_KERNEL);
if (!mp)
return -ENODEV;
...
dev_set_drvdata(&sdev->ofdev.dev, mp);
return 0;
...
}
static int mydevice_match(struct sbus_dev *sdev)
static int __devinit mydevice_probe(struct of_device *dev,
const struct of_device_id *match)
{
if (some_criteria(sdev))
return 1;
return 0;
struct sbus_dev *sdev = to_sbus_device(&dev->dev);
return mydevice_probe_one(sdev);
}
static void mydevice_probe(void)
static int __devexit mydevice_remove(struct of_device *dev)
{
struct sbus_bus *sbus;
struct sbus_dev *sdev;
struct sbus_dev *sdev = to_sbus_device(&dev->dev);
struct mydevice *mp = dev_get_drvdata(&dev->dev);
for_each_sbus(sbus) {
for_each_sbusdev(sdev, sbus) {
if (mydevice_match(sdev))
init_one_mydevice(sdev);
}
}
return mydevice_remove_one(sdev, mp);
}
All this does is walk through all SBUS devices in the
system, checks each to see if it is of the type which
your driver is written for, and if so it calls the init
routine to attach the device and prepare to drive it.
static struct of_device_id mydevice_match[] = {
{
.name = "mydevice",
},
{},
};
"init_one_mydevice" might do things like allocate software
state structures, map in I/O registers, place the hardware
into an initialized state, etc.
MODULE_DEVICE_TABLE(of, mydevice_match);
static struct of_platform_driver mydevice_driver = {
.name = "mydevice",
.match_table = mydevice_match,
.probe = mydevice_probe,
.remove = __devexit_p(mydevice_remove),
};
static int __init mydevice_init(void)
{
return of_register_driver(&mydevice_driver, &sbus_bus_type);
}
static void __exit mydevice_exit(void)
{
of_unregister_driver(&mydevice_driver);
}
module_init(mydevice_init);
module_exit(mydevice_exit);
The mydevice_match table is a series of entries which
describes what SBUS devices your driver is meant for. In the
simplest case you specify a string for the 'name' field. Every
SBUS device with a 'name' property matching your string will
be passed one-by-one to your .probe method.
You should store away your device private state structure
pointer in the drvdata area so that you can retrieve it later on
in your .remove method.
Any memory allocated, registers mapped, IRQs registered,
etc. must be undone by your .remove method so that all resources
of your device are relased by the time it returns.
You should _NOT_ use the for_each_sbus(), for_each_sbusdev(),
and for_all_sbusdev() interfaces. They are deprecated, will be
removed, and no new driver should reference them ever.
Mapping and Accessing I/O Registers
@ -263,10 +305,3 @@ discussed above and plus it handles both PCI and SBUS boards.
Lance driver abuses consistent mappings for data transfer.
It is a nifty trick which we do not particularly recommend...
Just check it out and know that it's legal.
Bad examples, do NOT use
drivers/video/cgsix.c
This one uses result of sbus_ioremap as if it is an address.
This does NOT work on sparc64 and therefore is broken. We will
convert it at a later date.