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    Subject[PATCH RFC 0/8] Dynamic clock devices
    Okay, here is a work in progress, not well tested, but I would like to
    get some feedback whether the direction is good or not.

    The first patch introduces clock devices which can appear and
    disappear like usb devices (and, I suppose, hot plug PCI but I am not
    too sure that what is offered here would really work in that case).
    The subsequent patches convert the clock_ and timer_ system calls, one
    by one.

    The clock_ syscalls are moved into a new file and they call the older
    posix functions when needed. The timer_ syscalls stay where they are,
    in posix-timers.c, since I did not want to change the fairly involved
    timer management code. Eventually, we could remove the posix clock_*
    functions for the CLOCK_* ids from posix-timers.c and rework them
    using the new dynamic clock api. That would leave just the timer code
    in posix-timers.c, as the file name suggests.

    I dropped the idea of having user space open a sysfs file in order to
    get a reference to a clock, since there are no open/release hooks
    within sysfs for drivers (coincidentally, there has been some talk
    about this on the lkml recently, but previously Greg KH object to
    abusing sysfs as a "clockfs").

    Instead, since many clocks (hpet, rtc, ptp, ...) will want to offer a
    custom chardev for special advanced functionality, the dynamic clock
    layer registers a cdev for the driver, placing its own hooks into the
    open/release methods. The driver thus needs to access its private data
    via a standard access method (not just by using fp->private_data). If
    a driver doesn't want any chardev functions, that is okay, too.

    Well, please take a look and let me know what you think.



    Richard Cochran (8):
    Introduce dynamic clock devices
    clock device: convert clock_gettime
    clock device: convert clock_getres
    clock device: convert clock_settime
    clock device: convert timer_create
    clock device: convert timer_delete
    clock device: convert timer_gettime
    clock device: convert timer_settime

    include/linux/clockdevice.h | 117 +++++++++++++++
    include/linux/posix-timers.h | 23 +++-
    include/linux/time.h | 2 +
    kernel/posix-timers.c | 51 +++++--
    kernel/time/Makefile | 3 +-
    kernel/time/clockdevice.c | 336 ++++++++++++++++++++++++++++++++++++++++++
    6 files changed, 518 insertions(+), 14 deletions(-)
    create mode 100644 include/linux/clockdevice.h
    create mode 100644 kernel/time/clockdevice.c

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      Last update: 2010-11-04 20:29    [W:0.023 / U:83.860 seconds]
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