path: root/include
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authorBjorn Helgaas <bjorn.helgaas@hp.com>2007-11-14 16:59:57 -0800
committerLinus Torvalds <torvalds@woody.linux-foundation.org>2007-11-14 18:45:41 -0800
commit9626f1f117be21b6e4b7a1cb49814fc065dd3d2d (patch)
tree259ba0c9362924d1a7e21a6befcc43e23f9fa9d5 /include
parentrtc: release correct region in error path (diff)
rtc: fall back to requesting only the ports we actually use
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>
Diffstat (limited to 'include')
1 files changed, 3 insertions, 0 deletions
diff --git a/include/linux/mc146818rtc.h b/include/linux/mc146818rtc.h
index 580b3f4956ee..2f4e957af656 100644
--- a/include/linux/mc146818rtc.h
+++ b/include/linux/mc146818rtc.h
@@ -109,8 +109,11 @@ struct cmos_rtc_board_info {
#ifndef ARCH_RTC_LOCATION /* Override by <asm/mc146818rtc.h>? */
#define RTC_IO_EXTENT 0x8
+#define RTC_IO_EXTENT_USED 0x2
#define RTC_IOMAPPED 1 /* Default to I/O mapping. */
#endif /* ARCH_RTC_LOCATION */
#endif /* _MC146818RTC_H */