2010/11/17 Pei Lin <telent997@xxxxxxxxx>
>
> 2010/11/17 Dave Hylands <dhylands@xxxxxxxxx>:
> > Hi lalith,
> >
> > On Tue, Nov 16, 2010 at 12:19 AM, laliteshwar yadav <lalit4294@xxxxxxxxx> wrote:
> >> how probe function works?
> >>
> >> how is it getting called?
> >>
> >> after registering the device driver who is the first function to call it..
> >
> > There are 2 things required for the probe function to be called: a
> > device and a driver.
> >
> > Normally, the architecture portion of the kernel registers devices for
> > all of the device that it has.
> > Then when you register a driver, it will detect if a device with a
> > matching name has been registered. If it finds a match, it will call
> > the probe routine.
> >
> > I normally work with linux in an embedded environment (ARM and MIPS),
> > not programming for linux under x86, so its possible that things
> > happen a little differently in that environment.
> >
>
> Dave gave the good explanation.
> In linux world, codes show everything.
> codes:
> /* Structure for a device driver */
> static struct platform_driver gfar_driver = {
> .probe = gfar_probe,
> .remove = gfar_remove,
> .driver = {
> .name = "fsl-gianfar",
> },
> };
>
>
> 1987 static int __init gfar_init(void)
> 1988 {
> 1989 int err = gfar_mdio_init();
> 1990
> 1991 if (err)
> 1992 return err;
> 1993
> 1994 err = platform_driver_register(&gfar_driver);
> 1995
> 1996 if (err)
> 1997 gfar_mdio_exit();
> 1998
> 1999 return err;
> 2000 }
>
>
> 443 int platform_driver_register(struct platform_driver *drv)
> 444 {
> 445 drv->driver.bus = &platform_bus_type;
> 446 if (drv->probe)
> 447 drv->driver.probe = platform_drv_probe;
> 448 if (drv->remove)
> 449 drv->driver.remove = platform_drv_remove;
> 450 if (drv->shutdown)
> 451 drv->driver.shutdown = platform_drv_shutdown;
> 452 if (drv->suspend)
> 453 drv->driver.suspend = platform_drv_suspend;
> 454 if (drv->resume)
> 455 drv->driver.resume = platform_drv_resume;
> 456 return driver_register(&drv->driver);
> 457 }
>
> 217 int driver_register(struct device_driver *drv)
> 218 {
> 219 int ret;
> 220
> 221 if ((drv->bus->probe && drv->probe) ||
> 222 (drv->bus->remove && drv->remove) ||
> 223 (drv->bus->shutdown && drv->shutdown))
> 224 printk(KERN_WARNING "Driver '%s' needs updating -
> please use "
> 225 "bus_type methods\n", drv->name);
> 226 ret = bus_add_driver(drv);
> 227 if (ret)
> 228 return ret;
> 229 ret = driver_add_groups(drv, drv->groups);
> 230 if (ret)
> 231 bus_remove_driver(drv);
> 232 return ret;
> 233 }
>
532 int bus_add_driver(struct device_driver * drv)
533 {
534 struct bus_type * bus = get_bus(drv->bus);
535 int error = 0;
536
537 if (bus) {
538 pr_debug("bus %s: add driver %s\n", bus->name, drv->name);
539 error = kobject_set_name(&drv->kobj, "%s", drv->name);
540 if (error) {
541 put_bus(bus);
542 return error;
543 }
544 drv->kobj.kset = &bus->drivers;
545 if ((error = kobject_register(&drv->kobj))) {
546 put_bus(bus);
547 return error;
548 }
549
550 down_write(&bus->subsys.rwsem);
551 driver_attach(drv);
552 up_write(&bus->subsys.rwsem);
553 module_add_driver(drv->owner, drv);
554
555 driver_add_attrs(bus, drv);
556 }
557 return error;
558 }
353 void driver_attach(struct device_driver * drv)
354 {
355 struct bus_type * bus = drv->bus;
356 struct list_head * entry;
357 int error;
358
359 if (!bus->match)
360 return;
361
362 list_for_each(entry, &bus->devices.list) {
363 struct device * dev = container_of(entry, struct
device, bus_list);
364 if (!dev->driver) {
365 error = driver_probe_device(drv, dev);
366 if (error && (error != -ENODEV))
367 /* driver matched but the probe failed */
368 printk(KERN_WARNING
369 "%s: probe of %s failed with
error %d\n",
370 drv->name, dev->bus_id, error);
371 }
372 }
373 }
284 int driver_probe_device(struct device_driver * drv, struct device * dev)
285 {
286 if (drv->bus->match && !drv->bus->match(dev, drv))
287 return -ENODEV;
288
289 dev->driver = drv;
290 if (drv->probe) {
291 int error = drv->probe(dev);
292 if (error) {
293 dev->driver = NULL;
294 return error;
295 }
296 }
297
298 device_bind_driver(dev);
299 return 0;
300 }
>
> > --
> > Dave Hylands
> > Shuswap, BC, Canada
> > http://www.DaveHylands.com/
> >
> > --
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> > Please read the FAQ at http://kernelnewbies.org/FAQ
> >
> >
>
>
>
> --
> Best Regards
> Lin
--
Best Regards
Lin
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