ref: 9f76a7f6819ac04552b4fb6588156f3e4089d1d7
dir: /os/boot/rpcg/i2c.c/
#include "boot.h"
/*
* basic read/write interface to mpc8xx I2C bus (master mode)
*/
typedef struct I2C I2C;
struct I2C {
uchar i2mod;
uchar rsv12a[3];
uchar i2add;
uchar rsv12b[3];
uchar i2brg;
uchar rsv12c[3];
uchar i2com;
uchar rsv12d[3];
uchar i2cer;
uchar rsv12e[3];
uchar i2cmr;
};
enum {
/* i2c-specific BD flags */
RxeOV= 1<<1, /* overrun */
TxS= 1<<10, /* transmit start condition */
TxeNAK= 1<<2, /* last transmitted byte not acknowledged */
TxeUN= 1<<1, /* underflow */
TxeCL= 1<<0, /* collision */
TxERR= (TxeNAK|TxeUN|TxeCL),
/* i2cmod */
REVD= 1<<5, /* =1, LSB first */
GCD= 1<<4, /* =1, general call address disabled */
FLT= 1<<3, /* =0, not filtered; =1, filtered */
PDIV= 3<<1, /* predivisor field */
EN= 1<<0, /* enable */
/* i2com */
STR= 1<<7, /* start transmit */
I2CM= 1<<0, /* master */
I2CS= 0<<0, /* slave */
/* i2cer */
TXE = 1<<4,
BSY = 1<<2,
TXB = 1<<1,
RXB = 1<<0,
/* port B bits */
I2CSDA = IBIT(27),
I2CSCL = IBIT(26),
Rbit = 1<<0, /* bit in address byte denoting read */
/* maximum I2C I/O (can change) */
MaxIO= 128,
Bufsize = MaxIO+4, /* extra space for address/clock bytes and alignment */
Freq = 100000,
I2CTimeout = 250, /* msec */
};
/* data cache needn't be flushed if buffers allocated in uncached INTMEM */
#define DCFLUSH(a,n)
/*
* I2C software structures
*/
struct Ctlr {
Lock;
QLock io;
int init;
I2C* i2c;
IOCparam* sp;
BD* rd;
BD* td;
int phase;
int timeout;
char* addr;
char* txbuf;
char* rxbuf;
};
typedef struct Ctlr Ctlr;
static Ctlr i2ctlr[1];
extern int predawn;
static void interrupt(Ureg*, void*);
static void
enable(void)
{
I2C *i2c;
i2c = i2ctlr->i2c;
i2c->i2cer = ~0; /* clear events */
eieio();
i2c->i2mod |= EN;
eieio();
i2c->i2cmr = TXE|BSY|TXB|RXB; /* enable all interrupts */
eieio();
}
static void
disable(void)
{
I2C *i2c;
i2c = i2ctlr->i2c;
i2c->i2cmr = 0; /* mask all interrupts */
i2c->i2mod &= ~EN;
}
/*
* called by the reset routine of any driver using the I2C
*/
void
i2csetup(void)
{
IMM *io;
I2C *i2c;
IOCparam *sp;
Ctlr *ctlr;
long f, e, emin;
int p, d, dmax;
ctlr = i2ctlr;
if(ctlr->init)
return;
print("i2c setup...\n");
ctlr->init = 1;
i2c = KADDR(INTMEM+0x860);
ctlr->i2c = i2c;
sp = KADDR(INTMEM+0x3c80);
ctlr->sp = sp;
disable();
if(ctlr->txbuf == nil){
ctlr->txbuf = ialloc(Bufsize, 2);
ctlr->addr = ctlr->txbuf+Bufsize;
}
if(ctlr->rxbuf == nil)
ctlr->rxbuf = ialloc(Bufsize, 2);
if(ctlr->rd == nil){
ctlr->rd = bdalloc(1);
ctlr->rd->addr = PADDR(ctlr->rxbuf);
ctlr->rd->length = 0;
ctlr->rd->status = BDWrap;
}
if(ctlr->td == nil){
ctlr->td = bdalloc(2);
ctlr->td->addr = PADDR(ctlr->txbuf);
ctlr->td->length = 0;
ctlr->td->status = BDWrap|BDLast;
}
/* select port pins */
io = ioplock();
io->pbdir |= I2CSDA | I2CSCL;
io->pbodr |= I2CSDA | I2CSCL;
io->pbpar |= I2CSDA | I2CSCL;
iopunlock();
/* explicitly initialise parameters, because InitRxTx can't be used (see i2c/spi relocation errata) */
sp = ctlr->sp;
sp->rbase = PADDR(ctlr->rd);
sp->tbase = PADDR(ctlr->td);
sp->rfcr = 0x18;
sp->tfcr = 0x18;
sp->mrblr = Bufsize;
sp->rstate = 0;
sp->rptr = 0;
sp->rbptr = sp->rbase;
sp->rcnt = 0;
sp->tstate = 0;
sp->tbptr = sp->tbase;
sp->tptr = 0;
sp->tcnt = 0;
eieio();
i2c->i2com = I2CM;
i2c->i2mod = 0; /* normal mode */
i2c->i2add = 0;
emin = Freq;
dmax = (m->cpuhz/Freq)/2-3;
for(d=0; d < dmax; d++){
for(p=3; p>=0; p--){
f = (m->cpuhz>>(p+2))/(2*(d+3));
e = Freq - f;
if(e < 0)
e = -e;
if(e < emin){
emin = e;
i2c->i2brg = d;
i2c->i2mod = (i2c->i2mod&~PDIV)|((3-p)<<1); /* set PDIV */
}
}
}
//print("i2brg=%d i2mod=#%2.2ux\n", i2c->i2brg, i2c->i2mod);
setvec(VectorCPIC+0x10, interrupt, i2ctlr);
}
enum {
Idling,
Done,
Busy,
Sending,
Recving,
};
static void
interrupt(Ureg*, void *arg)
{
int events;
Ctlr *ctlr;
I2C *i2c;
ctlr = arg;
i2c = ctlr->i2c;
events = i2c->i2cer;
eieio();
i2c->i2cer = events;
if(events & (BSY|TXE)){
print("I2C#%x\n", events);
if(ctlr->phase != Idling){
ctlr->phase = Idling;
}
}else{
if(events & TXB){
//print("i2c: xmt %d %4.4ux %4.4ux\n", ctlr->phase, ctlr->td->status, ctlr->td[1].status);
if(ctlr->phase == Sending){
ctlr->phase = Done;
}
}
if(events & RXB){
//print("i2c: rcv %d %4.4ux %d\n", ctlr->phase, ctlr->rd->status, ctlr->rd->length);
if(ctlr->phase == Recving){
ctlr->phase = Done;
}
}
}
}
static int
done(void *a)
{
return ((Ctlr*)a)->phase < Busy;
}
static void
i2cwait(Ctlr *ctlr)
{
int i;
ctlr->timeout = 0;
i = 0;
while(!done(ctlr)){
if(predawn){
if(++i > 100){
ctlr->phase = Done;
ctlr->timeout = 1;
return;
}
delay(1);
interrupt(nil, ctlr);
}
}
}
long
i2csend(int addr, void *buf, long n)
{
Ctlr *ctlr;
int i, p, s;
ctlr = i2ctlr;
if(n > MaxIO)
return -1;
i = 1;
ctlr->txbuf[0] = addr & ~1;
if(addr & 1){
ctlr->txbuf[1] = addr>>8;
i++;
}
memmove(ctlr->txbuf+i, buf, n);
DCFLUSH(ctlr->txbuf, Bufsize);
ctlr->phase = Sending;
ctlr->rd->status = BDEmpty|BDWrap|BDInt;
ctlr->td->addr = PADDR(ctlr->txbuf);
ctlr->td->length = n+i;
ctlr->td->status = BDReady|BDWrap|BDLast|BDInt;
enable();
ctlr->i2c->i2com = STR|I2CM;
eieio();
i2cwait(ctlr);
disable();
p = ctlr->phase;
s = ctlr->td->status;
if(s & BDReady || s & TxERR || p != Done || ctlr->timeout)
return -1;
return n;
}
long
i2crecv(int addr, void *buf, long n)
{
Ctlr *ctlr;
int p, s, flag;
BD *td;
long nr;
ctlr = i2ctlr;
if(n > MaxIO)
return -1;
ctlr->txbuf[0] = addr|Rbit;
if(addr & 1){ /* special select sequence */
ctlr->addr[0] = addr &~ 1;
ctlr->addr[1] = addr>>8;
}
DCFLUSH(ctlr->txbuf, Bufsize);
DCFLUSH(ctlr->rxbuf, Bufsize);
ctlr->phase = Recving;
ctlr->rd->addr = PADDR(ctlr->rxbuf);
ctlr->rd->status = BDEmpty|BDWrap|BDInt;
flag = 0;
td = ctlr->td;
td[1].status = 0;
if(addr & 1){
/* special select sequence */
td->addr = PADDR(ctlr->addr);
td->length = 2;
/* td->status made BDReady below */
td++;
flag = TxS;
}
td->addr = PADDR(ctlr->txbuf);
td->length = n+1;
td->status = BDReady|BDWrap|BDLast | flag; /* not BDInt: leave that to receive */
if(flag)
ctlr->td->status = BDReady;
enable();
ctlr->i2c->i2com = STR|I2CM;
eieio();
i2cwait(ctlr);
disable();
p = ctlr->phase;
s = ctlr->td->status;
if(flag)
s |= ctlr->td[1].status;
nr = ctlr->rd->length;
if(nr > n)
nr = n; /* shouldn't happen */
if(s & TxERR || s & BDReady || p != Done || ctlr->rd->status & BDEmpty || ctlr->timeout)
return -1;
memmove(buf, ctlr->rxbuf, nr);
return nr;
}