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authorMaciej W. Rozycki <macro@linux-mips.org>2014-06-06 14:35:49 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2014-06-06 16:08:07 -0700
commit31632dbdba85aafc8a6772d578c5c14f84a1fe17 (patch)
treeda8e9658492bbd13eaadf29e238ee857fca15b8a /include
parent809d9627087e1db63b8672c1f264af73b13116fb (diff)
drivers/rtc/rtc-cmos.c: drivers/char/rtc.c features for DECstation support
This brings in drivers/char/rtc.c functionality required for DECstation and, should the maintainers decide to switch, Alpha systems to use rtc-cmos. Specifically these features are made available: * RTC iomem rather than x86/PCI port I/O mapping, controlled with the RTC_IOMAPPED macro as with the original driver. The DS1287A chip in all DECstation systems is mapped in the host bus address space as a contiguous block of 64 32-bit words of which the least significant byte accesses the RTC chip for both reads and writes. All the address and data window register accesses are made transparently by the chipset glue logic so that the device appears directly mapped on the host bus. * A way to set the size of the address space explicitly with the newly-added `address_space' member of the platform part of the RTC device structure. This avoids the unreliable heuristics that does not work in a setup where the RTC is not explicitly accessed with the usual address and data window register pair. * The ability to use the RTC periodic interrupt as a system clock device, which is implemented by arch/mips/kernel/cevt-ds1287.c for DECstation systems and takes the RTC interrupt away from the RTC driver. Eventually hooking back to the clock device's interrupt handler should be possible for the purpose of the alarm clock and possibly also update-in-progress interrupt, but this is not done by this change. o To avoid interfering with the clock interrupt all the places where the RTC interrupt mask is fiddled with are only executed if and IRQ has been assigned to the RTC driver. o To avoid changing the clock setup Register A is not fiddled with if CMOS_RTC_FLAGS_NOFREQ is set in the newly-added `flags' member of the platform part of the RTC device structure. Originally, in drivers/char/rtc.c, this was keyed with the absence of the RTC interrupt, just like the interrupt mask, but there only the periodic interrupt frequency is set, whereas rtc-cmos also sets the divider bits. Therefore a new flag is introduced so that systems where the RTC interrupt is not usable rather than used as a system clock device can fully initialise the RTC. * A small clean-up is made to the IRQ assignment code that makes the IRQ number hardcoded to -1 rather than arbitrary -ENXIO (or whatever error happens to be returned by platform_get_irq) where no IRQ has been assigned to the RTC driver (NO_IRQ might be another candidate, but it looks like this macro has inconsistent or missing definitions and limited use and might therefore be unsafe). Verified to work correctly with a DECstation 5000/240 system. [akpm@linux-foundation.org: fix weird code layout] Signed-off-by: Maciej W. Rozycki <macro@linux-mips.org> Cc: Alessandro Zummo <a.zummo@towertech.it> 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')
-rw-r--r--include/linux/mc146818rtc.h4
1 files changed, 4 insertions, 0 deletions
diff --git a/include/linux/mc146818rtc.h b/include/linux/mc146818rtc.h
index 2f4e957af656..433e0c74d643 100644
--- a/include/linux/mc146818rtc.h
+++ b/include/linux/mc146818rtc.h
@@ -31,6 +31,10 @@ struct cmos_rtc_board_info {
void (*wake_on)(struct device *dev);
void (*wake_off)(struct device *dev);
+ u32 flags;
+#define CMOS_RTC_FLAGS_NOFREQ (1 << 0)
+ int address_space;
+
u8 rtc_day_alarm; /* zero, or register index */
u8 rtc_mon_alarm; /* zero, or register index */
u8 rtc_century; /* zero, or register index */