- According to ARM Dual-Timer Module (SP804) TRM (ARM DDI0271), -- Timer Value Register @ TIMER Base + 4 is Read-only. -- Prescale Value (Bits 3-2 of TIMER Control register) can only be one of 00,01,10. 11 is undefined. -- CFG_HZ for Versatile board is set to #define CFG_HZ (1000000 / 256) So Prescale bits is set to indicate - 8 Stages of Prescale, Clock divided by 256 - The Timer Control Register has one Undefined/Shouldn't Use Bit So we should do read/modify/write Operation
Signed-off-by: Gururaja Hebbar gururajakr@sanyo.co.in --- cpu/arm926ejs/versatile/timer.c | 37 +++++++++++++++++++++++++++++++++---- 1 files changed, 33 insertions(+), 4 deletions(-)
diff --git a/cpu/arm926ejs/versatile/timer.c b/cpu/arm926ejs/versatile/timer.c index 32872d2..17ba387 100755 --- a/cpu/arm926ejs/versatile/timer.c +++ b/cpu/arm926ejs/versatile/timer.c @@ -46,12 +46,41 @@ static ulong timestamp; static ulong lastdec;
-/* nothing really to do with interrupts, just starts up a counter. */ +#define TIMER_ENABLE (1 << 7) +#define TIMER_MODE_MSK (1 << 6) +#define TIMER_MODE_FR (0 << 6) +#define TIMER_MODE_PD (1 << 6) + +#define TIMER_INT_EN (1 << 5) +#define TIMER_PRS_MSK (3 << 2) +#define TIMER_PRS_8S (1 << 3) +#define TIMER_SIZE_MSK (1 << 2) +#define TIMER_ONE_SHT (1 << 0) + int timer_init (void) { - *(volatile ulong *)(CFG_TIMERBASE + 0) = CFG_TIMER_RELOAD; /* TimerLoad */ - *(volatile ulong *)(CFG_TIMERBASE + 4) = CFG_TIMER_RELOAD; /* TimerValue */ - *(volatile ulong *)(CFG_TIMERBASE + 8) = 0x8C; + ulong TmrCntrlVal; + + /*1st disable the Timer*/ + TmrCntrlVal = *(volatile ulong *)(CFG_TIMERBASE + 8); + TmrCntrlVal &= ~TIMER_ENABLE; + *(volatile ulong *)(CFG_TIMERBASE + 8) = TmrCntrlVal; + + /* The Timer Control Register has one Undefined/Shouldn't Use Bit + * So we should do read/modify/write Operation + */ + + /* Timer Mode : Free Running + * Interrupt : Disabled + * Prescale : 8 Stage, Clk/256 + * Tmr Siz : 16 Bit Counter + * Tmr in Wrapping Mode + */ + TmrCntrlVal = *(volatile ulong *)(CFG_TIMERBASE + 8); + TmrCntrlVal &= ~(TIMER_MODE_MSK | TIMER_INT_EN | TIMER_PRS_MSK | TIMER_SIZE_MSK | TIMER_ONE_SHT ); + TmrCntrlVal |= (TIMER_ENABLE | TIMER_PRS_8S); + + *(volatile ulong *)(CFG_TIMERBASE + 8) = TmrCntrlVal;
/* init the timestamp and lastdec value */ reset_timer_masked();