[ARM] 2871/1: Fixes an issue with gettimeofday not working correctly on Intel IOP3xx...

Patch from Adam Brooks

The current gettimeofday implementation for the IOP3xx processors reads the contents of the timer interrupt register and does math on the value to figure out exactly what time it is.  To do this it  multiplies the contents of the timer register with a large constant.  The result is then divided by a large constant.  Unfortunately the result of the first multiplication is often too large for the register to hold.  The solution is to combine the two large constants to a single smaller constant at compile time.  Then the timer value can be divided by single smaller constant without any overflow issues.

Signed-off-by: Adam Brooks <adam.j.brooks@intel.com>
Signed-off-by: Deepak Saxena <dsaxena@plexity.net>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

diff --git a/arch/arm/mach-iop3xx/iop321-time.c b/arch/arm/mach-iop3xx/iop321-time.c
index d53af16695023d16f7867b74c35b56c2dfa952cc..0039793b694a20cd63da8930386a5ba3c6cbf9d1 100644 (file)
--- a/arch/arm/mach-iop3xx/iop321-time.c
+++ b/arch/arm/mach-iop3xx/iop321-time.c
@@ -60,7 +60,7 @@ static unsigned long iop321_gettimeoffset(void)
        /*
         * Now convert them to usec.
         */
-       usec = (unsigned long)(elapsed * (tick_nsec / 1000)) / LATCH;
+       usec = (unsigned long)(elapsed / (CLOCK_TICK_RATE/1000000));
 
        return usec;
 }

diff --git a/arch/arm/mach-iop3xx/iop331-time.c b/arch/arm/mach-iop3xx/iop331-time.c
index 1a6d9d661e4b8ee851ef0867be104309eebe917f..8eddfac7e2b046450d74a6074837b9f73e0fff1b 100644 (file)
--- a/arch/arm/mach-iop3xx/iop331-time.c
+++ b/arch/arm/mach-iop3xx/iop331-time.c
@@ -58,7 +58,7 @@ static unsigned long iop331_gettimeoffset(void)
        /*
         * Now convert them to usec.
         */
-       usec = (unsigned long)(elapsed * (tick_nsec / 1000)) / LATCH;
+       usec = (unsigned long)(elapsed / (CLOCK_TICK_RATE/1000000));
 
        return usec;
 }