Messages in this thread | | | Date | Thu, 4 Nov 2004 09:42:45 -0800 | From | Greg KH <> | Subject | Re: patch for sysfs in the cyclades driver |
| |
On Thu, Nov 04, 2004 at 12:29:25PM -0200, Marcelo Tosatti wrote: > On Thu, Nov 04, 2004 at 08:58:21AM -0800, Roland Dreier wrote: > > Marcelo> The problem was class_simple only contains the "dev" > > Marcelo> attribute. You can't add other attributes to it. > > > > I believe, based on the comment in class_simple.c: > > > > Any further sysfs files that might be required can be created using this pointer. > > > > and the implementation in in drivers/scsi/st.c, that there's no > > problem adding attributes to a device in a simple class. You can just > > use class_set_devdata() on your class_device to set whatever context > > you need to get back to your internal structures, and then use > > class_device_create_file() to add the attributes. > > > > I assume this is OK (since there is already one in-kernel driver doing > > it), but Greg, can you confirm that it's definitely OK for a driver to > > use class_set_devdata() on a class_device from class_simple_device_add()? > > Hi Roland, > > Oh thanks, I didnt knew the existance of such possibily. > > I once asked here on the list: > > --------- > > Hope this is not a FAQ. > > I want to export some read-only attributes (statistics) from cyclades.c char > driver to userspace via sysfs. > > I can't figure out the right place to do it - I could create a class under > /sys/class/cyclades for example, but that doesnt sound right since this > is not a "class" of device, but a device itself. > > Hooking the statistics into /sys/class/tty/ttyC$/ sounds reasonable, but > its not possible it seems because "tty" is a class_simple class, which only implements > the "dev" attribute. > > ------ Greg answer was: > > For a driver only attribute, you want them to show up in the place for > the driver (like under /sys/bus/pci/driver/MY_FOO_DRIVER/). To do that > use the DRIVER_ATTR() and the driver_add_file() functions. For > examples, see the other drivers that use these functions. > > > But I hope you are right - /sys/class/tty/tty$/ > sounds the correct place for those files - I thought a "class_tty" > class was required for new attributes.
No, Roland is right, just use the class_device pointer you get back from the core when a tty device is created.
Right now we aren't saving the pointer anywhere (see tty_register_device() for where it is created.) Just add that to the proper tty_device structure, and you should be fine (yeah, it's going to be a pain, and you will quickly see why I didn't do that in the first place, but it is going to need to be changed eventually...)
Good luck,
greg k-h - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
| |