ptimer.c

包括ＥＰＡ协议栈

#include "tc.h"
#define PTIMER_GLOBALS
#include "ptimer.h"
#include "eb40a.h"

#define TC0_DEFAULT_MODE                (AT91C_TC_WAVESEL_UP_AUTO | AT91C_TC_ASWTRG_CLEAR | AT91C_TC_BSWTRG_CLEAR | AT91C_TC_TCCLKS_MCK32 | AT91C_TC_WAVE)
#define CRITICAL_MILLISECONDS           (25)
#define PTP_TIMER_TICKS                 (62500)              // Determines ticks to gernorate a interrupt
#define PTP_CRITICAL_NANOSECONDS        (975000000)          // When CurTime.nasecs > this value, CurTime.secs should add 1 in interrupt
#define PTP_INTERVAL_NANOSECONDS        (25000000)	         // Nanoseconds between two interrupts
#define PTP_TICK_NANOSECONDS            (400)                // Nano-Seconds during one crystal ticks

static Time CurTime;

void TC0IntHandler(void);

void PTimerStart(void) {

	CurTime.secs = 0;
	CurTime.nasecs = 0;
	TimerInit(AT91C_BASE_TC0,
            AT91C_TC_CPCTRG|TC_CLKS_MCK32,
            AT91C_AIC_PRIOR_HIGHEST - 4,
            AT91C_ID_TC0,
            AT91C_ID_TC0,
            AT91C_TC_CPCS, 
            TC0IntHandler);
   TCStart(AT91C_BASE_TC0, PTP_TIMER_TICKS);
}

void Getime(PTime ptime) {
	CpuSr sr;
	uint32 cv, bpend;

	SpinLock(sr);
	cv = TCGetCV(AT91C_BASE_TC0);
	bpend = AT91C_BASE_AIC->AIC_IPR & (0x01 << AT91C_ID_TC0);
	ptime->secs = CurTime.secs;
	ptime->nasecs = CurTime.nasecs;
	SpinUnLock(sr);
	if((bpend != 0) && (cv < 0xFF)) {
		ptime->nasecs += PTP_INTERVAL_NANOSECONDS;
	}
	ptime->nasecs += (cv * PTP_TICK_NANOSECONDS);
	if(ptime->nasecs >= 1000000000) {
		ptime->nasecs -= 1000000000;
		ptime->secs += 1;
	}
}

void Setime(PTime ptime) {

	TCReload(AT91C_BASE_TC0, PTP_TIMER_TICKS);
	CurTime.secs = ptime->secs;
	CurTime.nasecs = ptime->nasecs;
}

void TC0Int(void) {
	uint32 status;
	CpuSr sr;
	
	status = AT91C_BASE_TC0->TC_SR;

	if(CurTime.nasecs >= PTP_CRITICAL_NANOSECONDS) {
		SpinLock(sr);
		CurTime.secs += 1;
		CurTime.nasecs -= PTP_CRITICAL_NANOSECONDS;
		SpinUnLock(sr);
	}
	else {
		CurTime.nasecs += PTP_INTERVAL_NANOSECONDS;
	}
}