• Bjorn Helgaas's avatar
    rtc: fall back to requesting only the ports we actually use · 9626f1f1
    Bjorn Helgaas authored
    Firmware like PNPBIOS or ACPI can report the address space consumed by the
    RTC.  The actual space consumed may be less than the size (RTC_IO_EXTENT)
    assumed by the RTC driver.
    
    The PNP core doesn't request resources yet, but I'd like to make it do so.
    If/when it does, the RTC_IO_EXTENT request may fail, which prevents the RTC
    driver from loading.
    
    Since we only use the RTC index and data registers at RTC_PORT(0) and
    RTC_PORT(1), we can fall back to requesting just enough space for those.
    
    If the PNP core requests resources, this results in typical I/O port usage
    like this:
    
        0070-0073 : 00:06		<-- PNP device 00:06 responds to 70-73
          0070-0071 : rtc		<-- RTC driver uses only 70-71
    
    instead of the current:
    
        0070-0077 : rtc		<-- RTC_IO_EXTENT == 8
    Signed-off-by: default avatarBjorn Helgaas <bjorn.helgaas@hp.com>
    Cc: Alessandro Zummo <a.zummo@towertech.it>
    Cc: David Brownell <david-b@pacbell.net>
    Cc: Ralf Baechle <ralf@linux-mips.org>
    Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
    Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
    9626f1f1
mc146818rtc.h 4.22 KB