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/*
* bcm283[56] 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
* Cortex-a7 has local generic timers per cpu (which we run at 1MHz)
*
* Use system timer 3 (64 bits) for hzclock interrupts and fastticks
* For smp on bcm2836, use local generic timer for interrupts on cpu1-3
* 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"
#include "ureg.h"
#include "arm.h"
enum {
SYSTIMERS = VIRTIO+0x3000,
ARMTIMER = VIRTIO+0xB400,
Localctl = 0x00,
Prescaler = 0x08,
SystimerFreq = 1*Mhz,
MaxPeriod = SystimerFreq / HZ,
MinPeriod = 10,
};
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,
/* generic timer (cortex-a7) */
Enable = 1<<0,
Imask = 1<<1,
Istatus = 1<<2,
};
static void
clockintr(Ureg *ureg, void *)
{
Systimers *tn;
if(m->machno != 0)
panic("cpu%d: unexpected system timer interrupt", m->machno);
tn = (Systimers*)SYSTIMERS;
/* dismiss interrupt */
tn->cs = 1<<3;
timerintr(ureg, 0);
}
static void
localclockintr(Ureg *ureg, void *)
{
if(m->machno == 0)
panic("cpu0: Unexpected local generic timer interrupt");
timerintr(ureg, 0);
}
void
clockshutdown(void)
{
Armtimer *tm;
tm = (Armtimer*)ARMTIMER;
tm->ctl = 0;
}
void
clockinit(void)
{
Systimers *tn;
Armtimer *tm;
ulong t0, t1, tstart, tend;
if(((cprdsc(0, CpID, CpIDfeat, 1) >> 16) & 0xF) != 0) {
/* generic timer supported */
cpwrsc(0, CpTIMER, CpTIMERphys, CpTIMERphysval, ~0);
if(m->machno == 0){
cpwrsc(0, CpTIMER, CpTIMERphys, CpTIMERphysctl, Imask);
/* input clock is 19.2Mhz crystal */
*(ulong*)(ARMLOCAL + Localctl) = 0;
/* divide by (2^31/Prescaler) */
*(ulong*)(ARMLOCAL + Prescaler) = (((uvlong)SystimerFreq<<31)/19200000)&~1UL;
} else {
cpwrsc(0, CpTIMER, CpTIMERphys, CpTIMERphysctl, Enable);
intrenable(IRQcntpns, localclockintr, nil, 0, "clock");
}
}
tn = (Systimers*)SYSTIMERS;
tstart = tn->clo;
do{
t0 = lcycles();
}while(tn->clo == tstart);
tend = tstart + (SystimerFreq/100);
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;
if(m->machno == 0){
tn->c3 = tn->clo - 1;
intrenable(IRQtimer3, clockintr, nil, 0, "clock");
tm = (Armtimer*)ARMTIMER;
tm->load = 0;
tm->ctl = TmrPrescale1|CntEnable|CntWidth32;
}
}
void
timerset(uvlong next)
{
Systimers *tn;
uvlong now;
long period;
now = fastticks(nil);
period = next - now;
if(period < MinPeriod)
period = MinPeriod;
else if(period > MaxPeriod)
period = MaxPeriod;
if(m->machno)
cpwrsc(0, CpTIMER, CpTIMERphys, CpTIMERphysval, period);
else{
tn = (Systimers*)SYSTIMERS;
tn->c3 = tn->clo + period;
}
}
uvlong
fastticks(uvlong *hz)
{
Systimers *tn;
ulong lo, hi;
uvlong now;
if(hz)
*hz = SystimerFreq;
tn = (Systimers*)SYSTIMERS;
do{
hi = tn->chi;
lo = tn->clo;
}while(tn->chi != hi);
now = (uvlong)hi<<32 | lo;
return now;
}
ulong
perfticks(void)
{
Armtimer *tm;
tm = (Armtimer*)ARMTIMER;
return tm->count;
}
void
armtimerset(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;
}
}
ulong
µs(void)
{
if(SystimerFreq != 1*Mhz)
return fastticks2us(fastticks(nil));
return ((Systimers*)SYSTIMERS)->clo;
}
void
microdelay(int n)
{
ulong now;
now = µs();
while(µs() - now < n);
}
void
delay(int n)
{
while(--n >= 0)
microdelay(1000);
}
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