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, 1 insertions, 9 deletions

diff --git a/arch/alpha/kernel/core_marvel.c b/arch/alpha/kernel/core_marvel.c
index 9cd8dca742a7..e302daecbe56 100644
--- a/arch/alpha/kernel/core_marvel.c
+++ b/arch/alpha/kernel/core_marvel.c
@@ -658,16 +658,8 @@ __marvel_rtc_io(u8 b, unsigned long addr, int write)
 		rtc_access.data = bcd2bin(b);
 		rtc_access.function = 0x48 + !write;	/* GET/PUT_TOY */
 
-#ifdef CONFIG_SMP
-		if (smp_processor_id() != boot_cpuid)
-			smp_call_function_single(boot_cpuid,
-						 __marvel_access_rtc,
-						 &rtc_access, 1);
-		else
-			__marvel_access_rtc(&rtc_access);
-#else
 		__marvel_access_rtc(&rtc_access);
-#endif
+
 		ret = bin2bcd(rtc_access.data);
 		break;