diff options
Diffstat (limited to 'cpu/arm1136')
| -rw-r--r-- | cpu/arm1136/mx31/interrupts.c | 79 |
1 files changed, 50 insertions, 29 deletions
diff --git a/cpu/arm1136/mx31/interrupts.c b/cpu/arm1136/mx31/interrupts.c index 6e08c71..cd57071 100644 --- a/cpu/arm1136/mx31/interrupts.c +++ b/cpu/arm1136/mx31/interrupts.c @@ -27,30 +27,49 @@ #define TIMER_BASE 0x53f90000 /* General purpose timer 1 */ /* General purpose timers registers */ -#define GPTCR __REG(TIMER_BASE) /* Control register */ -#define GPTPR __REG(TIMER_BASE + 0x4) /* Prescaler register */ -#define GPTSR __REG(TIMER_BASE + 0x8) /* Status register */ -#define GPTCNT __REG(TIMER_BASE + 0x24) /* Counter register */ +#define GPTCR __REG(TIMER_BASE) /* Control register */ +#define GPTPR __REG(TIMER_BASE + 0x4) /* Prescaler register */ +#define GPTSR __REG(TIMER_BASE + 0x8) /* Status register */ +#define GPTCNT __REG(TIMER_BASE + 0x24) /* Counter register */ /* General purpose timers bitfields */ -#define GPTCR_SWR (1<<15) /* Software reset */ -#define GPTCR_FRR (1<<9) /* Freerun / restart */ -#define GPTCR_CLKSOURCE_32 (4<<6) /* Clock source */ -#define GPTCR_TEN (1) /* Timer enable */ +#define GPTCR_SWR (1 << 15) /* Software reset */ +#define GPTCR_FRR (1 << 9) /* Freerun / restart */ +#define GPTCR_CLKSOURCE_32 (4 << 6) /* Clock source */ +#define GPTCR_TEN 1 /* Timer enable */ + +/* "time" is measured in 1 / CFG_HZ seconds, "tick" is internal timer period */ +#ifdef CONFIG_MX31_TIMER_HIGH_PRECISION +/* ~0.4% error - measured with stop-watch on 100s boot-delay */ +#define TICK_TO_TIME(t) ((t) * CFG_HZ / CONFIG_MX31_CLK32) +#define TIME_TO_TICK(t) ((unsigned long long)(t) * CONFIG_MX31_CLK32 / CFG_HZ) +#define US_TO_TICK(t) (((unsigned long long)(t) * CONFIG_MX31_CLK32 + \ + 999999) / 1000000) +#else +/* ~2% error */ +#define TICK_PER_TIME ((CONFIG_MX31_CLK32 + CFG_HZ / 2) / CFG_HZ) +#define US_PER_TICK (1000000 / CONFIG_MX31_CLK32) +#define TICK_TO_TIME(t) ((t) / TICK_PER_TIME) +#define TIME_TO_TICK(t) ((unsigned long long)(t) * TICK_PER_TIME) +#define US_TO_TICK(t) (((t) + US_PER_TICK - 1) / US_PER_TICK) +#endif static ulong timestamp; static ulong lastinc; /* nothing really to do with interrupts, just starts up a counter. */ +/* The 32768Hz 32-bit timer overruns in 131072 seconds */ int interrupt_init (void) { int i; /* setup GP Timer 1 */ GPTCR = GPTCR_SWR; - for ( i=0; i<100; i++) GPTCR = 0; /* We have no udelay by now */ + for (i = 0; i < 100; i++) + GPTCR = 0; /* We have no udelay by now */ GPTPR = 0; /* 32Khz */ - GPTCR |= GPTCR_CLKSOURCE_32 | GPTCR_TEN; /* Freerun Mode, PERCLK1 input */ + /* Freerun Mode, PERCLK1 input */ + GPTCR |= GPTCR_CLKSOURCE_32 | GPTCR_TEN; return 0; } @@ -67,7 +86,7 @@ void reset_timer(void) reset_timer_masked(); } -ulong get_timer_masked (void) +unsigned long long get_ticks (void) { ulong now = GPTCNT; /* current tick value */ @@ -80,6 +99,17 @@ ulong get_timer_masked (void) return timestamp; } +ulong get_timer_masked (void) +{ + /* + * get_ticks() returns a long long (64 bit), it wraps in + * 2^64 / CONFIG_MX31_CLK32 = 2^64 / 2^15 = 2^49 ~ 5 * 10^14 (s) ~ + * 5 * 10^9 days... and get_ticks() * CFG_HZ wraps in + * 5 * 10^6 days - long enough. + */ + return TICK_TO_TIME(get_ticks()); +} + ulong get_timer (ulong base) { return get_timer_masked () - base; @@ -87,29 +117,20 @@ ulong get_timer (ulong base) void set_timer (ulong t) { + timestamp = TIME_TO_TICK(t); } /* delay x useconds AND perserve advance timstamp value */ void udelay (unsigned long usec) { - ulong tmo, tmp; - - 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); - } - - tmp = get_timer (0); /* get current timestamp */ - if ( (tmo + tmp + 1) < tmp )/* if setting this forward will roll time stamp */ - reset_timer_masked (); /* reset "advancing" timestamp to 0, set lastinc value */ - else - tmo += tmp; /* else, set advancing stamp wake up time */ - while (get_timer_masked () < tmo)/* loop till event */ - /*NOP*/; + unsigned long long tmp; + ulong tmo; + + tmo = US_TO_TICK(usec); + tmp = get_ticks() + tmo; /* get current timestamp */ + + while (get_ticks() < tmp) /* loop till event */ + /*NOP*/; } void reset_cpu (ulong addr) |