xref: /inferno-os/os/mpc/spi.c (revision 74a4d8c26dd3c1e9febcb717cfd6cb6512991a7a)

#include "u.h"
#include "../port/lib.h"
#include "mem.h"
#include "dat.h"
#include "fns.h"
#include "io.h"
#include "../port/error.h"

/*
 * basic read/write interface to mpc8xx Serial Peripheral Interface;
 * used by devtouch.c and devspi.c
 */

typedef struct Ctlr Ctlr;

enum {
	/* spi-specific BD flags */
	BDContin=	1<<9,	/* continuous mode */
	RxeOV=		1<<1,	/* overrun */
	TxeUN=		1<<1,	/* underflow */
	BDme=		1<<0,	/* multimaster error */
	BDrxerr=		RxeOV|BDme,
	BDtxerr=		TxeUN|BDme,

	/* spmod */
	MLoop=	1<<14,	/* loopback mode */
	MClockInv= 1<<13,	/* inactive state of SPICLK is high */
	MClockPhs= 1<<12,	/* SPCLK starts toggling at beginning of transfer */
	MDiv16=	1<<11,	/* use BRGCLK/16 as input to SPI baud rate */
	MRev=	1<<10,	/* normal operation */
	MMaster=	1<<9,
	MSlave=	0<<9,
	MEnable=	1<<8,
	/* LEN, PS fields */

	/* spcom */
	STR=		1<<7,	/* start transmit */

	/* spie */
	MME =	1<<5,
	TXE =	1<<4,
	BSY =	1<<2,
	TXB =	1<<1,
	RXB =	1<<0,

	/* port B bits */
	SPIMISO =	IBIT(28),	/* master mode input */
	SPIMOSI = IBIT(29),	/* master mode output */
	SPICLK = IBIT(30),

	/* maximum SPI I/O (can change) */
	Bufsize =	64,
};

/*
 * SPI software structures
 */

struct Ctlr {
	Lock;
	QLock	io;
	int	init;
	SPI*	spi;
	IOCparam*	sp;

	BD*	rd;
	BD*	td;
	int	phase;
	Rendez	r;
	char*	txbuf;
	char*	rxbuf;
};

static	Ctlr	spictlr[1];

/* dcflush isn't needed if rxbuf and txbuf allocated in uncached IMMR memory */
#define	DCFLUSH(a,n)

static	void	interrupt(Ureg*, void*);

/*
 * called by the reset routine of any driver using the SPI
 */
void
spireset(void)
{
	IMM *io;
	SPI *spi;
	IOCparam *sp;
	CPMdev *cpm;
	Ctlr *ctlr;

	ctlr = spictlr;
	if(ctlr->init)
		return;
	ctlr->init = 1;
	cpm = cpmdev(CPspi);
	spi = cpm->regs;
	ctlr->spi = spi;
	sp = cpm->param;
	if(sp == nil){
		print("SPI: can't allocate new parameter memory\n");
		return;
	}
	ctlr->sp = sp;

	if(ctlr->rxbuf == nil)
		ctlr->rxbuf = cpmalloc(Bufsize, 2);
	if(ctlr->txbuf == nil)
		ctlr->txbuf = cpmalloc(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(1);
		ctlr->td->addr = PADDR(ctlr->txbuf);
		ctlr->td->length = 0;
		ctlr->td->status = BDWrap|BDLast;
	}

	/* select port pins */
	io = ioplock();
	io->pbdir |= SPICLK | SPIMOSI | SPIMISO;
	io->pbpar |= SPICLK | SPIMOSI | SPIMISO;
	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();

	spi->spmode = MDiv16 | MRev | MMaster | ((8-1)<<4) | 1;	/* 8 bit characters */
	if(0)
		spi->spmode |= MLoop;	/* internal loop back mode for testing */

	spi->spie = ~0;	/* clear events */
	eieio();
	spi->spim = MME|TXE|BSY|TXB|RXB;
	eieio();
	spi->spmode |= MEnable;

	intrenable(VectorCPIC+cpm->irq, interrupt, spictlr, BUSUNKNOWN, "spi");

}

enum {
	Idling,
	Waitval,
	Readyval
};

static void
interrupt(Ureg*, void *arg)
{
	int events;
	Ctlr *ctlr;
	SPI *spi;

	ctlr = arg;
	spi = ctlr->spi;
	events = spi->spie;
	eieio();
	spi->spie = events;
	if(events & (MME|BSY|TXE)){
		print("SPI#%x\n", events);
		if(ctlr->phase != Idling){
			ctlr->phase = Idling;
			wakeup(&ctlr->r);
		}
	}else if(events & RXB){
		if(ctlr->phase == Waitval){
			ctlr->phase = Readyval;
			wakeup(&ctlr->r);
		}
	}
}

static int
done(void *a)
{
	return ((Ctlr*)a)->phase != Waitval;
}

/*
 * send `nout' bytes on SPI from `out' and read as many bytes of reply into buffer `in';
 * return the number of bytes received, or -1 on error.
 */
long
spioutin(void *out, long nout, void *in)
{
	Ctlr *ctlr;
	int nb, p;

	ctlr = spictlr;
	if(nout > Bufsize)
		return -1;
	qlock(&ctlr->io);
	if(waserror()){
		qunlock(&ctlr->io);
		return -1;
	}
	if(ctlr->phase != Idling)
		sleep(&ctlr->r, done, ctlr);
	memmove(ctlr->txbuf, out, nout);
	DCFLUSH(ctlr->txbuf, Bufsize);
	DCFLUSH(ctlr->rxbuf, Bufsize);
	ilock(ctlr);
	ctlr->phase = Waitval;
	ctlr->td->length = nout;
	ctlr->rd->status = BDEmpty|BDWrap|BDInt;
	ctlr->td->status = BDReady|BDWrap|BDLast;
	eieio();
	ctlr->spi->spcom = STR;
	eieio();
	iunlock(ctlr);
	sleep(&ctlr->r, done, ctlr);
	nb = ctlr->rd->length;
	if(nb > nout)
		nb = nout;	/* shouldn't happen */
	p = ctlr->phase;
	poperror();
	qunlock(&ctlr->io);
	if(p != Readyval)
		return -1;
	memmove(in, ctlr->rxbuf, nb);
	return nb;
}