alpha: fix RTC on marvel

Unlike other alphas, marvel doesn't have real PC-style CMOS clock hardware
- RTC accesses are emulated via PAL calls.  Unfortunately, for unknown
reason these calls work only on CPU #0.  So current implementation for
arbitrary CPU makes CMOS_READ/WRITE to be executed on CPU #0 via IPI.
However, for obvious reason this doesn't work with standard
get/set_rtc_time() functions, where a bunch of CMOS accesses is done with
disabled interrupts.

Solved by making the IPI calls for entire get/set_rtc_time() functions,
not for individual CMOS accesses.  Which is also a lot more effective
performance-wise.

The patch is largely based on the code from Jay Estabrook.
My changes:
- tweak asm-generic/rtc.h by adding a couple of #defines to
  avoid a massive code duplication in arch/alpha/include/asm/rtc.h;
- sys_marvel.c: fix get/set_rtc_time() return values (Jay's FIXMEs).

NOTE: this fixes *only* LIB_RTC drivers.  Legacy (CONFIG_RTC) driver
wont't work on marvel.  Actually I think that we should just disable
CONFIG_RTC on alpha (maybe in 2.6.30?), like most other arches - AFAIK,
all modern distributions use LIB_RTC anyway.

Signed-off-by: Ivan Kokshaysky <ink@jurassic.park.msu.ru>
Cc: Richard Henderson <rth@twiddle.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 11 insertions, 3 deletions

diff --git a/include/asm-generic/rtc.h b/include/asm-generic/rtc.h
index 89061c1a67d4..763e3b060f43 100644
--- a/include/asm-generic/rtc.h
+++ b/include/asm-generic/rtc.h
@@ -42,7 +42,7 @@ static inline unsigned char rtc_is_updating(void)
         return uip;
 }
 
-static inline unsigned int get_rtc_time(struct rtc_time *time)
+static inline unsigned int __get_rtc_time(struct rtc_time *time)
 {
         unsigned char ctrl;
         unsigned long flags;
@@ -108,8 +108,12 @@ static inline unsigned int get_rtc_time(struct rtc_time *time)
         return RTC_24H;
 }
 
+#ifndef get_rtc_time
+#define get_rtc_time    __get_rtc_time
+#endif
+
 /* Set the current date and time in the real time clock. */
-static inline int set_rtc_time(struct rtc_time *time)
+static inline int __set_rtc_time(struct rtc_time *time)
 {
         unsigned long flags;
         unsigned char mon, day, hrs, min, sec;
@@ -190,11 +194,15 @@ static inline int set_rtc_time(struct rtc_time *time)
         return 0;
 }
 
+#ifndef set_rtc_time
+#define set_rtc_time    __set_rtc_time
+#endif
+
 static inline unsigned int get_rtc_ss(void)
 {
         struct rtc_time h;
 
-        get_rtc_time(&h);
+        __get_rtc_time(&h);
         return h.tm_sec;
 }