ref: 7a29422cfefaf76315eafa82ca606f9ded9517b3
dir: /os/pxa/i2c.c/
/*
* basic read/write interface to PXA25x IC bus (master mode)
* 7 bit addressing only.
* TO DO:
* - enable unit clock
*/
#include "u.h"
#include "../port/lib.h"
#include "mem.h"
#include "dat.h"
#include "fns.h"
#include "../port/error.h"
#include "io.h"
typedef struct Ctlr Ctlr;
typedef struct I2Cregs I2Cregs;
struct I2Cregs {
ulong ibmr; /* bus monitor */
ulong pad0;
ulong idbr; /* data buffer */
ulong pad1;
ulong icr; /* control */
ulong pad2;
ulong isr; /* status */
ulong pad3;
ulong isar; /* slave address */
};
enum {
/* ibmr */
Scls= 1<<1, /* SCL pin status */
Sdas= 1<<0, /* SDA pin status */
/* icr */
Fm= 1<<15, /* =0, 100 kb/sec; =1, 400 kb/sec */
Ur= 1<<14, /* reset the i2c unit only */
Sadie= 1<<13, /* slave address detected interrupt enable */
Aldie= 1<<12, /* arbitration loss detected interrupt enable (master mode) */
Ssdie= 1<<11, /* stop detected interrupt enable (slave mode) */
Beie= 1<<10, /* bus error interrupt enable */
Irfie= 1<<9, /* idbr receive full, interrupt enable */
Iteie= 1<<8, /* idbr transmit empty interrupt enable */
Gcd= 1<<7, /* disable response to general call message (slave); must be set if master uses g.c. */
Scle= 1<<6, /* SCL enable: enable clock output for master mode */
Iue= 1<<5, /* enable i2c (default: slave) */
Ma= 1<<4, /* master abort (send STOP without data) */
Tb= 1<<3, /* transfer byte on i2c bus */
Ack= 0<<2,
Nak= 1<<2,
Stop= 1<<1, /* send a stop */
Start= 1<<0, /* send a stop */
/* isr */
Bed= 1<<10, /* bus error detected */
Sad= 1<<9, /* slave address detected */
Gcad= 1<<8, /* general call address detected */
Irf= 1<<7, /* idbr receive full */
Ite= 1<<6, /* idbr transmit empty */
Ald= 1<<5, /* arbitration loss detected (multi-master) */
Ssd= 1<<4, /* slave stop detected */
Ibb= 1<<3, /* i2c bus is busy */
Ub= 1<<2, /* unit is busy (between start and stop) */
Nakrcv= 1<<1, /* nak received or sent a NAK */
Rwm= 1<<0, /* =0, master transmit (or slave receive); =1, master receive (or slave transmit) */
Err= Bed | Ssd,
/* isar address (0x7F bits) */
/* others */
Rbit = 1<<0, /* bit in address byte denoting read */
Wbit= 0<<0,
MaxIO = 8192, /* largest transfer done at once (can change) */
MaxSA= 2, /* largest subaddress; could be FIFOsize */
Bufsize = MaxIO, /* subaddress bytes don't go in buffer */
Freq = 0, /* set to Fm for high-speed */
// I2Ctimeout = 125, /* msec (can change) */
I2Ctimeout = 10000, /* msec when Chatty */
Chatty = 0,
};
#define DPRINT if(Chatty)print
/*
* I2C software structures
*/
struct Ctlr {
Lock;
QLock io;
int init;
int polling; /* eg, when running before system set up */
I2Cregs* regs; /* hardware registers */
/* controller state (see below) */
int status;
int phase;
Rendez r;
/* transfer parameters */
int addr;
int salen; /* bytes remaining of subaddress */
int offset; /* sub-addressed offset */
int cntl; /* everything but transfer length */
int rdcount; /* requested read transfer size */
Block* b;
};
enum {
/* Ctlr.state */
Idle,
Done,
Failed,
Busy,
Address,
Subaddress,
Read,
Write,
Halting,
};
static Ctlr i2cctlr[1];
static void interrupt(Ureg*, void*);
static int readyxfer(Ctlr*, int);
static void rxstart(Ctlr*);
static void txstart(Ctlr*);
static void stopxfer(Ctlr*);
static void txoffset(Ctlr*, ulong, int);
static int idlectlr(Ctlr*);
static void
i2cdump(char *t, I2Cregs *i2c)
{
iprint("i2c %s: ibmr=%.4lux icr=%.4lux isr=%.4lux\n", t, i2c->ibmr, i2c->icr, i2c->isr);
}
static void
initialise(I2Cregs *i2c, int eintr)
{
int ctl;
/* initialisation (see p. 9-11 on) */
i2c->isar = 0;
ctl = Freq | Gcd | Scle | Iue;
if(eintr)
ctl |= Beie | Irfie; /* Iteie set by txstart */
i2c->icr = ctl;
if(Chatty)
iprint("ctl=%4.4ux icr=%4.4lux\n", ctl, i2c->icr);
}
/*
* called by the reset routine of any driver using the IIC
*/
void
i2csetup(int polling)
{
I2Cregs *i2c;
Ctlr *ctlr;
ctlr = i2cctlr;
ctlr->polling = polling;
i2c = KADDR(PHYSI2C);
ctlr->regs = i2c;
if(!polling){
if(ctlr->init == 0){
initialise(i2c, 1);
ctlr->init = 1;
intrenable(IRQ, IRQi2c, interrupt, i2cctlr, "i2c");
if(Chatty)
i2cdump("init", i2c);
}
}else
initialise(i2c, 0);
}
static void
done(Ctlr *ctlr)
{
ctlr->phase = Done;
wakeup(&ctlr->r);
}
static void
failed(Ctlr *ctlr)
{
ctlr->phase = Failed;
wakeup(&ctlr->r);
}
static void
interrupt(Ureg*, void *arg)
{
int sts, idl;
Ctlr *ctlr;
Block *b;
I2Cregs *i2c;
char xx[12];
ctlr = arg;
i2c = ctlr->regs;
idl = (i2c->ibmr & 3) == 3;
if(Chatty && ctlr->phase != Read && ctlr->phase != Write){
snprint(xx, sizeof(xx), "intr %d", ctlr->phase);
i2cdump(xx, i2c);
}
sts = i2c->isr;
if(sts & (Bed | Sad | Gcad | Ald))
iprint("i2c: unexpected status: %.4ux", sts);
i2c->isr = sts;
ctlr->status = sts;
i2c->icr &= ~(Start | Stop | Nak | Ma | Iteie);
if(sts & Err){
failed(ctlr);
return;
}
switch(ctlr->phase){
default:
iprint("i2c: unexpected interrupt: p-%d s=%.4ux\n", ctlr->phase, sts);
break;
case Halting:
ctlr->phase = Idle;
break;
case Subaddress:
if(ctlr->salen){
/* push out next byte of subaddress */
ctlr->salen -= 8;
i2c->idbr = ctlr->offset >> ctlr->salen;
i2c->icr |= Aldie | Tb | Iteie;
break;
}
/* subaddress finished */
if(ctlr->cntl & Rbit){
/* must readdress if reading to change mode */
i2c->idbr = (ctlr->addr << 1) | Rbit;
i2c->icr |= Start | Tb | Iteie;
ctlr->phase = Address; /* readdress */
break;
}
/* FALL THROUGH if writing */
case Address:
/* if not sub-addressed, rxstart/txstart */
if(ctlr->cntl & Rbit)
rxstart(ctlr);
else
txstart(ctlr);
break;
case Read:
b = ctlr->b;
if(b == nil)
panic("i2c: no buffer");
/* master receive: next byte */
if(sts & Irf){
ctlr->rdcount--;
if(b->wp < b->lim)
*b->wp++ = i2c->idbr;
}
if(ctlr->rdcount <= 0 || sts & Nakrcv || idl){
if(Chatty)
iprint("done: %.4ux\n", sts);
done(ctlr);
break;
}
rxstart(ctlr);
break;
case Write:
b = ctlr->b;
if(b == nil)
panic("i2c: no buffer");
/* account for data transmitted */
if(BLEN(b) <= 0 || sts & Nakrcv){
done(ctlr);
break;
}
txstart(ctlr);
break;
}
}
static int
isdone(void *a)
{
return ((Ctlr*)a)->phase < Busy;
}
static int
i2cerror(char *s)
{
DPRINT("i2c error: %s\n", s);
if(up)
error(s);
/* no current process, don't call error */
return -1;
}
static char*
startxfer(I2Cdev *d, int op, Block *b, int n, ulong offset)
{
I2Cregs *i2c;
Ctlr *ctlr;
int i, p, s;
ctlr = i2cctlr;
if(up){
qlock(&ctlr->io);
if(waserror()){
qunlock(&ctlr->io);
nexterror();
}
}
ilock(ctlr);
if(!idlectlr(ctlr)){
iunlock(ctlr);
if(up)
error("bus confused");
return "bus confused";
}
if(ctlr->phase >= Busy)
panic("i2c: ctlr busy");
ctlr->cntl = op;
ctlr->b = b;
ctlr->rdcount = n;
ctlr->addr = d->addr;
i2c = ctlr->regs;
ctlr->salen = d->salen*8;
ctlr->offset = offset;
if(ctlr->salen){
ctlr->phase = Subaddress;
op = Wbit;
}else
ctlr->phase = Address;
i2c->idbr = (d->addr<<1) | op; /* 7-bit address + R/nW */
i2c->icr |= Start | Tb | Iteie;
if(Chatty)
i2cdump("start", i2c);
iunlock(ctlr);
/* wait for it */
if(ctlr->polling){
for(i=0; !isdone(ctlr); i++){
delay(2);
interrupt(nil, ctlr);
}
}else
tsleep(&ctlr->r, isdone, ctlr, I2Ctimeout);
ilock(ctlr);
p = ctlr->phase;
s = ctlr->status;
ctlr->b = nil;
if(ctlr->phase != Done && ctlr->phase != Idle)
stopxfer(ctlr);
iunlock(ctlr);
if(up){
poperror();
qunlock(&ctlr->io);
}
if(p != Done || s & (Bed|Ald)){ /* CHECK; time out */
if(s & Ald)
return "i2c lost arbitration";
if(s & Bed)
return "i2c bus error";
if(s & Ssd)
return "i2c transfer aborted"; /* ?? */
if(0 && p != Done)
return "i2c timed out";
sprint(up->genbuf, "i2c error: phase=%d status=%.4ux", p, s);
return up->genbuf;
}
return nil;
}
long
i2csend(I2Cdev *d, void *buf, long n, ulong offset)
{
Block *b;
char *e;
if(n <= 0)
return 0;
if(n > MaxIO)
n = MaxIO;
if(up){
b = allocb(n);
if(b == nil)
error(Enomem);
if(waserror()){
freeb(b);
nexterror();
}
}else{
b = iallocb(n);
if(b == nil)
return -1;
}
memmove(b->wp, buf, n);
b->wp += n;
e = startxfer(d, 0, b, 0, offset);
if(up)
poperror();
n -= BLEN(b); /* residue */
freeb(b);
if(e)
return i2cerror(e);
return n;
}
long
i2crecv(I2Cdev *d, void *buf, long n, ulong offset)
{
Block *b;
long nr;
char *e;
if(n <= 0)
return 0;
if(n > MaxIO)
n = MaxIO;
if(up){
b = allocb(n);
if(b == nil)
error(Enomem);
if(waserror()){
freeb(b);
nexterror();
}
}else{
b = iallocb(n);
if(b == nil)
return -1;
}
e = startxfer(d, Rbit, b, n, offset);
nr = BLEN(b);
if(nr > 0)
memmove(buf, b->rp, nr);
if(up)
poperror();
freeb(b);
if(e)
return i2cerror(e);
return nr;
}
/*
* the controller must be locked for the following functions
*/
static int
readyxfer(Ctlr *ctlr, int phase)
{
I2Cregs *i2c;
i2c = ctlr->regs;
if((i2c->isr & Bed) != 0){
failed(ctlr);
return 0;
}
ctlr->phase = phase;
return 1;
}
/*
* start a master transfer to receive the next byte of data
*/
static void
rxstart(Ctlr *ctlr)
{
Block *b;
int cntl;
b = ctlr->b;
if(b == nil || ctlr->rdcount<= 0){
done(ctlr);
return;
}
if(!readyxfer(ctlr, Read))
return;
cntl = Aldie | Tb;
if(ctlr->rdcount == 1)
cntl |= Stop | Nak | Iteie; /* last byte of transfer */
ctlr->regs->icr |= cntl;
}
/*
* start a master transfer to send the next chunk of data
*/
static void
txstart(Ctlr *ctlr)
{
Block *b;
int cntl;
long nb;
I2Cregs *i2c;
b = ctlr->b;
if(b == nil || (nb = BLEN(b)) <= 0){
done(ctlr);
return;
}
if(!readyxfer(ctlr, Write))
return;
i2c = ctlr->regs;
i2c->idbr = *b->rp++;
cntl = Aldie | Tb | Iteie;
if(nb == 1)
cntl |= Stop;
i2c->icr |= cntl;
}
/*
* stop a transfer if one is in progress
*/
static void
stopxfer(Ctlr *ctlr)
{
I2Cregs *i2c;
i2c = ctlr->regs;
if((i2c->isr & Ub) == 0){
ctlr->phase = Idle;
return;
}
if((i2c->isr & Ibb) == 0 && ctlr->phase != Halting){
ctlr->phase = Halting; /* interrupt will clear the state */
i2c->icr |= Ma;
}
/* if that doesn't clear it by the next operation, idlectlr will do so below */
}
static int
idlectlr(Ctlr *ctlr)
{
I2Cregs *i2c;
i2c = ctlr->regs;
if((i2c->isr & Ibb) == 0){
if((i2c->isr & Ub) == 0){
ctlr->phase = Idle;
return 1;
}
iprint("i2c: bus free, ctlr busy: isr=%.4lux icr=%.4lux\n", i2c->isr, i2c->icr);
}
/* hit it with the hammer, soft reset */
iprint("i2c: soft reset\n");
i2c->icr = Ur;
iunlock(ctlr);
delay(1);
ilock(ctlr);
initialise(i2c, !ctlr->polling);
ctlr->phase = Idle;
return (i2c->isr & (Ibb | Ub)) == 0;
}