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    SubjectRe: patch for sysfs in the cyclades driver
    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.

    -
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