/*  * This file is part of the UCB release of Plan 9. It is subject to the license * terms in the LICENSE file found in the top-level directory of this * distribution and at http://akaros.cs.berkeley.edu/files/Plan9License. No * part of the UCB release of Plan 9, including this file, may be copied, * modified, propagated, or distributed except according to the terms contained * in the LICENSE file. */ /* * bcm2835 timers *	System timers run at 1MHz (timers 1 and 2 are used by GPU) *	ARM timer usually runs at 250MHz (may be slower in low power modes) *	Cycle counter runs at 700MHz (unless overclocked) *    All are free-running up-counters * * Use system timer 3 (64 bits) for hzclock interrupts and fastticks * Use ARM timer (32 bits) for perfticks * Use ARM timer to force immediate interrupt * Use cycle counter for cycles() */ #include "u.h"#include "../port/lib.h"#include "mem.h"#include "dat.h"#include "fns.h"#include "io.h" enum {	SYSTIMERS	= VIRTIO+0x3000,	ARMTIMER	= VIRTIO+0xB400, 	SystimerFreq	= 1*Mhz,	MaxPeriod	= SystimerFreq / HZ,	MinPeriod	= SystimerFreq / (100*HZ),}; typedef struct Systimers Systimers;typedef struct Armtimer Armtimer; struct Systimers {	u32int	cs;	u32int	clo;	u32int	chi;	u32int	c0;	u32int	c1;	u32int	c2;	u32int	c3;}; struct Armtimer {	u32int	load;	u32int	val;	u32int	ctl;	u32int	irqack;	u32int	irq;	u32int	maskedirq;	u32int	reload;	u32int	predivider;	u32int	count;}; enum {	CntPrescaleShift= 16,	/* freq is sys_clk/(prescale+1) */	CntPrescaleMask	= 0xFF,	CntEnable	= 1<<9,	TmrDbgHalt	= 1<<8,	TmrEnable	= 1<<7,	TmrIntEnable	= 1<<5,	TmrPrescale1	= 0x00<<2,	TmrPrescale16	= 0x01<<2,	TmrPrescale256	= 0x02<<2,	CntWidth16	= 0<<1,	CntWidth32	= 1<<1,}; static voidclockintr(Ureg *ureg, void *){	Systimers *tn; 	tn = (Systimers*)SYSTIMERS;	/* dismiss interrupt */	tn->cs = 1<<3;	timerintr(ureg, 0);} voidclockshutdown(void){	Armtimer *tm; 	tm = (Armtimer*)ARMTIMER;	tm->ctl = 0;	wdogoff();} voidclockinit(void){	Systimers *tn;	Armtimer *tm;	u32int t0, t1, tstart, tend; 	tn = (Systimers*)SYSTIMERS;	tm = (Armtimer*)ARMTIMER;	tm->load = 0;	tm->ctl = TmrPrescale1|CntEnable|CntWidth32; 	tstart = tn->clo;	do{		t0 = lcycles();	}while(tn->clo == tstart);	tend = tstart + 10000;	do{		t1 = lcycles();	}while(tn->clo != tend);	t1 -= t0;	m->cpuhz = 100 * t1;	m->cpumhz = (m->cpuhz + Mhz/2 - 1) / Mhz;	m->cyclefreq = m->cpuhz; 	tn->c3 = tn->clo - 1;	intrenable(IRQtimer3, clockintr, nil, 0, "clock");} voidtimerset(uvlong next){	Systimers *tn;	vlong now, period; 	tn = (Systimers*)SYSTIMERS;	now = fastticks(nil);	period = next - fastticks(nil);	if(period < MinPeriod)		next = now + MinPeriod;	else if(period > MaxPeriod)		next = now + MaxPeriod;	tn->c3 = (ulong)next;} uvlongfastticks(uvlong *hz){	Systimers *tn;	ulong lo, hi; 	tn = (Systimers*)SYSTIMERS;	if(hz)		*hz = SystimerFreq;	do{		hi = tn->chi;		lo = tn->clo;	}while(tn->chi != hi);	m->fastclock = (uvlong)hi<<32 | lo;	return m->fastclock;} ulongperfticks(void){	Armtimer *tm; 	tm = (Armtimer*)ARMTIMER;	return tm->count;} voidarmtimerset(int n){	Armtimer *tm; 	tm = (Armtimer*)ARMTIMER;	if(n > 0){		tm->ctl |= TmrEnable|TmrIntEnable;		tm->load = n;	}else{		tm->load = 0;		tm->ctl &= ~(TmrEnable|TmrIntEnable);		tm->irq = 1;	}} ulongµs(void){	if(SystimerFreq != 1*Mhz)		return fastticks2us(fastticks(nil));	return fastticks(nil);} voidmicrodelay(int n){	Systimers *tn;	u32int now, diff; 	tn = (Systimers*)SYSTIMERS;	diff = n + 1;	now = tn->clo;	while(tn->clo - now < diff)		;} voiddelay(int n){	while(--n >= 0)		microdelay(1000);}