diff options
Diffstat (limited to 'cpu/arm925t/interrupts.c')
| -rw-r--r-- | cpu/arm925t/interrupts.c | 67 |
1 files changed, 45 insertions, 22 deletions
diff --git a/cpu/arm925t/interrupts.c b/cpu/arm925t/interrupts.c index 132af1a3c..7897184fc 100644 --- a/cpu/arm925t/interrupts.c +++ b/cpu/arm925t/interrupts.c @@ -185,9 +185,14 @@ int interrupt_init (void) { int32_t val; + /* Start the decrementer ticking down from 0xffffffff */ *((int32_t *) (CFG_TIMERBASE + LOAD_TIM)) = TIMER_LOAD_VAL; val = MPUTIM_ST | MPUTIM_AR | MPUTIM_CLOCK_ENABLE | (CFG_PVT << MPUTIM_PTV_BIT); *((int32_t *) (CFG_TIMERBASE + CNTL_TIMER)) = val; + + /* init the timestamp and lastdec value */ + reset_timer_masked(); + return (0); } @@ -210,7 +215,7 @@ void set_timer (ulong t) timestamp = t; } -/* very rough timer... */ +/* delay x useconds AND perserve advance timstamp value */ void udelay (unsigned long usec) { #ifdef CONFIG_INNOVATOROMAP1510 @@ -220,16 +225,24 @@ void udelay (unsigned long usec) for (i = time_remaining; i > 0; i--) { } #else + ulong tmo, tmp; - ulong tmo; - - tmo = usec / 1000; - tmo *= CFG_HZ; - tmo /= 1000; + if(usec >= 1000){ /* if "big" number, spread normalization to seconds */ + tmo = usec / 1000; /* start to normalize for usec to ticks per sec */ + tmo *= CFG_HZ; /* find number of "ticks" to wait to achieve target */ + tmo /= 1000; /* finish normalize. */ + }else{ /* else small number, don't kill it prior to HZ multiply */ + tmo = usec * CFG_HZ; + tmo /= (1000*1000); + } - tmo += get_timer (0); + tmp = get_timer (0); /* get current timestamp */ + if( (tmo + tmp) < tmp ) /* if setting this fordward will roll time stamp */ + reset_timer_masked (); /* reset "advancing" timestamp to 0, set lastdec value */ + else + tmo += tmp; /* else, set advancing stamp wake up time */ - while (get_timer_masked () < tmo) + while (get_timer_masked () < tmo)/* loop till event */ /*NOP*/; #endif } @@ -237,19 +250,23 @@ void udelay (unsigned long usec) void reset_timer_masked (void) { /* reset time */ - lastdec = READ_TIMER; - timestamp = 0; + lastdec = READ_TIMER; /* capure current decrementer value time */ + timestamp = 0; /* start "advancing" time stamp from 0 */ } ulong get_timer_masked (void) { - ulong now = READ_TIMER; /* current tick value */ + ulong now = READ_TIMER; /* current tick value */ - if (lastdec >= now) { /* did I roll (rem decrementer) */ + if (lastdec >= now) { /* normal mode (non roll) */ /* normal mode */ - timestamp += lastdec - now; /* record amount of time since last check */ - } else { - /* we have an overflow ... */ + timestamp += lastdec - now; /* move stamp fordward with absoulte diff ticks */ + } else { /* we have overflow of the count down timer */ + /* nts = ts + ld + (TLV - now) + * ts=old stamp, ld=time that passed before passing through -1 + * (TLV-now) amount of time after passing though -1 + * nts = new "advancing time stamp"...it could also roll and cause problems. + */ timestamp += lastdec + TIMER_LOAD_VAL - now; } lastdec = now; @@ -257,6 +274,7 @@ ulong get_timer_masked (void) return timestamp; } +/* waits specified delay value and resets timestamp */ void udelay_masked (unsigned long usec) { #ifdef CONFIG_INNOVATOROMAP1510 @@ -265,15 +283,20 @@ void udelay_masked (unsigned long usec) for (i=time_remaining; i>0; i--) { } #else - ulong tmo; + ulong tmo, tmp; - tmo = usec / 1000; - tmo *= CFG_HZ; - tmo /= 1000; + if(usec >= 1000){ /* if "big" number, spread normalization to seconds */ + tmo = usec / 1000; /* start to normalize for usec to ticks per sec */ + tmo *= CFG_HZ; /* find number of "ticks" to wait to achieve target */ + tmo /= 1000; /* finish normalize. */ + }else{ /* else small number, don't kill it prior to HZ multiply */ + tmo = usec * CFG_HZ; + tmo /= (1000*1000); + } - reset_timer_masked (); + reset_timer_masked (); /* set "advancing" timestamp to 0, set lastdec vaule */ - while (get_timer_masked () < tmo) + while (get_timer_masked () < tmo) /* wait for time stamp to overtake tick number.*/ /*NOP*/; #endif } @@ -292,7 +315,7 @@ unsigned long long get_ticks(void) * On ARM it returns the number of timer ticks per second. */ ulong get_tbclk (void) -{ /* poor timer, may need to improve especiall for bootp. */ +{ ulong tbclk; tbclk = CFG_HZ; |