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