From 9626f1f117be21b6e4b7a1cb49814fc065dd3d2d Mon Sep 17 00:00:00 2001 From: Bjorn Helgaas Date: Wed, 14 Nov 2007 16:59:57 -0800 Subject: 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 Cc: Alessandro Zummo Cc: David Brownell Cc: Ralf Baechle Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- include/linux/mc146818rtc.h | 3 +++ 1 file changed, 3 insertions(+) (limited to 'include') 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 ? */ #define RTC_IO_EXTENT 0x8 +#define RTC_IO_EXTENT_USED 0x2 #define RTC_IOMAPPED 1 /* Default to I/O mapping. */ +#else +#define RTC_IO_EXTENT_USED RTC_IO_EXTENT #endif /* ARCH_RTC_LOCATION */ #endif /* _MC146818RTC_H */ -- cgit v1.2.3