177cbace73
this provides basic console support using the ARC bios routines theu uartarcs driver. and has native seeq ethernet driver which was written by reading the 2ed devseq driver as i have no documentation on the hardware. mmu and trap code is based on the routerboard kernel.
168 lines
3 KiB
C
168 lines
3 KiB
C
#include "u.h"
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#include "../port/lib.h"
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#include "mem.h"
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#include "dat.h"
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#include "fns.h"
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#include "io.h"
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#include "ureg.h"
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enum {
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Cyccntres = 2, /* counter advances at ½ clock rate */
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Basetickfreq = 150*Mhz / Cyccntres, /* sgi/indy */
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Instrs = 10*Mhz,
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};
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static long
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issue1loop(void)
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{
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register int i;
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long st;
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i = Instrs;
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st = perfticks();
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do {
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--i; --i; --i; --i; --i; --i; --i; --i; --i; --i;
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--i; --i; --i; --i; --i; --i; --i; --i; --i; --i;
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--i; --i; --i; --i; --i; --i; --i; --i; --i; --i;
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--i; --i; --i; --i; --i; --i; --i; --i; --i; --i;
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--i; --i; --i; --i; --i; --i; --i; --i; --i; --i;
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--i; --i; --i; --i; --i; --i; --i; --i; --i; --i;
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--i; --i; --i; --i; --i; --i; --i; --i; --i; --i;
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--i; --i; --i; --i; --i; --i; --i; --i; --i; --i;
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--i; --i; --i; --i; --i; --i; --i; --i; --i; --i;
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--i; --i; --i; --i; --i;
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/* omit 3 (--i) to account for conditional branch, nop & jump */
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i -= 1+3; /* --i plus 3 omitted (--i) instructions */
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} while(--i >= 0);
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return perfticks() - st;
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}
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/* estimate instructions/s. */
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static int
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guessmips(long (*loop)(void), char *)
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{
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int s;
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long cyc;
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do {
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s = splhi();
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cyc = loop();
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splx(s);
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if (cyc < 0)
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iprint("again...");
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} while (cyc < 0);
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/*
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* Instrs instructions took cyc cycles @ Basetickfreq Hz.
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* round the result.
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*/
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return (((vlong)Basetickfreq * Instrs) / cyc + Mhz/2) / Mhz;
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}
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void
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clockinit(void)
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{
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int mips;
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/*
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* calibrate fastclock
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*/
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mips = guessmips(issue1loop, "single");
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/*
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* m->delayloop should be the number of delay loop iterations
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* needed to consume 1 ms, assuming 2 instr'ns in the delay loop.
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*/
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m->delayloop = mips*Mhz / (1000 * 2);
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if(m->delayloop == 0)
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m->delayloop = 1;
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m->speed = mips;
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m->hz = m->speed*Mhz;
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m->maxperiod = Basetickfreq / HZ;
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m->minperiod = Basetickfreq / (100*HZ);
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wrcompare(rdcount()+m->maxperiod);
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intron(INTR7);
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}
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void
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clock(Ureg *ur)
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{
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wrcompare(rdcount()+m->maxperiod); /* side-effect: dismiss intr */
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timerintr(ur, 0);
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}
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void
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microdelay(int n)
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{
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ulong now;
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now = µs();
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while(µs() - now < n);
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}
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void
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delay(int n)
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{
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while(--n >= 0)
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microdelay(1000);
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}
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ulong
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µs(void)
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{
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return fastticks2us(fastticks(nil));
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}
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uvlong
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fastticks(uvlong *hz)
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{
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int x;
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ulong delta, count;
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if(hz)
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*hz = Basetickfreq;
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/* avoid reentry on interrupt or trap, to prevent recursion */
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x = splhi();
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count = rdcount();
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if(rdcompare() - count > m->maxperiod)
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wrcompare(count+m->maxperiod);
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if (count < m->lastcount) /* wrapped around? */
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delta = count + ((1ull<<32) - m->lastcount);
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else
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delta = count - m->lastcount;
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m->lastcount = count;
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m->fastticks += delta;
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splx(x);
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return m->fastticks;
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}
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ulong
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perfticks(void)
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{
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return rdcount();
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}
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void
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timerset(Tval next)
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{
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int x;
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long period;
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if(next == 0)
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return;
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x = splhi(); /* don't let us get scheduled */
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period = next - fastticks(nil);
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if(period > m->maxperiod - m->minperiod)
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period = m->maxperiod;
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else if(period < m->minperiod)
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period = m->minperiod;
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wrcompare(rdcount()+period);
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splx(x);
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}
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