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: Bjorn 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: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
9626f1f117