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    SubjectRe: [rtc-linux] [PATCH/RFC 0/5] Generic RTC class driver
    On Fri, 20 Feb 2009, Alessandro Zummo wrote:
    > On Fri, 20 Feb 2009 16:46:44 +0100
    > Geert Uytterhoeven <> wrote:
    > > Fortunately there already exists a generic RTC class driver: "rtc-parisc".
    > > Despite it's name, it's platform-independent, as it's build on top of the RTC
    > > abstraction used by "genrtc".
    > >
    > > This patch series
    > > - adds a missing module alias to rtc-parisc,
    > > - renames rtc-parisc to rtc-generic,
    > > - converts the architectures that currently have CONFIG_GEN_RTC enabled in
    > > their defconfig (m68k, parisc, powerpc) to rtc-generic,
    > > - removes the obsolete rtc-ppc driver,
    > > - removes the old genrtc driver.
    > >
    > > Note that genrtc may be used on other archictectures as well: at least alpha
    > > has the required infrastructure ([gs]et_rtc_time()). The Kconfig rules allow
    > > genrtc to be enabled on several others (cris, h8300, mn10300, um, x86, xtensa).
    > >
    > > Furthermore genrtc and rtc-generic are not 100% userspace compatible:
    > > - /dev/rtc provided by genrtc uses a misc character device (10:135),
    > > - /dev/rtc provided by rtc-generic uses a dynamic character device.
    > Hello,
    > my opinion on this kind of stuff is that I want to avoid the layering
    > of implementations under the rtc subsystem. I'd rather prefer that each
    > rtc device had its own driver.
    > I've made error in the past, by accepting such kind of drivers, and
    > would like to avoid that it happens again.

    So you want us to kill the ppc_md.[gs]et_rtc_time() [ppc], mach_hwclk() [m68k],
    mach_gettod() [m68knommu] (and probably a few other) abstractions, and move all
    RTC code out of arch/ into seperate drivers under drivers/rtc/ instead?

    What about ppc_md.get_boot_time() [ppc]?
    Please note that the functions above may also be used for very early clock
    setting (e.g. time_init()) and in read_persistent_clock().
    How should we handle these?

    Even on x86 there seems to be way too much RTC logic in arch/x86/kernel/rtc.c
    (e.g. mach_get_cmos_time()), which is duplicated in drivers/rtc/rtc-cmos.c
    through the inline function __get_rtc_time() in include/asm-generic/rtc.h
    (clever, hardware-specific stuff in asm-generic ;-)

    > Regarding the user space, the assumption that a device has
    > a fixed major:minor number should be dropped as well.

    I know. But it's a userland-visible change, so I wanted to explicit point to

    With kind regards,

    Geert Uytterhoeven
    Software Architect

    Sony Techsoft Centre Europe
    The Corporate Village · Da Vincilaan 7-D1 · B-1935 Zaventem · Belgium

    Phone: +32 (0)2 700 8453
    Fax: +32 (0)2 700 8622

    A division of Sony Europe (Belgium) N.V.
    VAT BE 0413.825.160 · RPR Brussels
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