ref: 3ccc8224be30ed01a30a4d92ca868df4e98a13fd
dir: /sys/src/9/kw/devtwsi.c/
/* * kirkwood two-wire serial interface (TWSI) and * inter-integrated circuit (I²C) driver */ #include "u.h" #include "../port/lib.h" #include "mem.h" #include "dat.h" #include "fns.h" #include "../port/error.h" #include "io.h" enum { Qdir, Qtwsi, }; typedef struct Kwtwsi Kwtwsi; typedef struct Twsi Twsi; struct Kwtwsi { /* device registers */ ulong saddr; ulong data; ulong ctl; union { ulong status; /* ro */ ulong rate; /* wo: baud rate */ }; ulong saddrext; uchar _pad0[0x1c-0x14]; ulong reset; uchar _pad1[0x98-0x20]; ulong initlastdata; }; enum { Twsidowrite, Twsidoread, /* ctl bits */ Twsiack = 1<<2, /* recv'd data; clear to ack */ Twsiint = 1<<3, /* interrupt conditions true */ Twsistop = 1<<4, Twsistart = 1<<5, Twsislaveen = 1<<6, Twsiinten = 1<<7, /* interrupts enabled */ /* status codes */ SStart = 0x08, SWa = 0x18, SWda = 0x28, SRa = 0x40, SRda = 0x50, SRna = 0x58, }; struct Twsi { QLock; Rendez nextbyte; /* remainder is state needed to track the operation in progress */ int intr; int done; uchar *bp; /* current ptr into buf */ uchar *end; ulong addr; /* device address */ char *error; }; static Twsi twsi; static Dirtab twsidir[] = { ".", {Qdir, 0, QTDIR}, 0, DMDIR|0555, "twsi", {Qtwsi}, 0, 0660, }; static char Eabsts[] = "abnormal status"; static void twsifinish(void) { Kwtwsi *krp = (Kwtwsi *)soc.twsi; twsi.done = 1; krp->ctl |= Twsistop; coherence(); } static void twsidoread(void) { Kwtwsi *krp = (Kwtwsi *)soc.twsi; switch(krp->status){ case SStart: krp->data = twsi.addr << 1 | Twsidoread; break; case SRa: krp->ctl |= Twsiack; break; case SRda: if(twsi.bp < twsi.end) { *twsi.bp++ = krp->data; krp->ctl |= Twsiack; } else krp->ctl &= ~Twsiack; break; case SRna: twsifinish(); break; default: twsifinish(); twsi.error = Eabsts; break; } } static void twsidowrite(void) { Kwtwsi *krp = (Kwtwsi *)soc.twsi; switch(krp->status){ case SStart: krp->data = twsi.addr << 1 | Twsidowrite; break; case SWa: case SWda: if(twsi.bp < twsi.end) krp->data = *twsi.bp++; else twsifinish(); break; default: twsifinish(); twsi.error = Eabsts; break; } } static int twsigotintr(void *) { return twsi.intr; } static long twsixfer(uchar *buf, ulong len, ulong offset, void (*op)(void)) { ulong off; char *err; Kwtwsi *krp = (Kwtwsi *)soc.twsi; qlock(&twsi); twsi.bp = buf; twsi.end = buf + len; twsi.addr = offset; twsi.done = twsi.intr = 0; twsi.error = nil; krp->ctl = (krp->ctl & ~Twsiint) | Twsistart; coherence(); while (!twsi.done) { sleep(&twsi.nextbyte, twsigotintr, 0); twsi.intr = 0; (*op)(); /* signal to start new op & extinguish intr source */ krp->ctl &= ~Twsiint; coherence(); krp->ctl |= Twsiinten; coherence(); } twsifinish(); err = twsi.error; off = twsi.bp - buf; twsi.bp = nil; /* prevent accidents */ qunlock(&twsi); if(err) error(err); return off; } static void interrupt(Ureg *, void *) { Kwtwsi *krp = (Kwtwsi *)soc.twsi; twsi.intr = 1; wakeup(&twsi.nextbyte); krp->ctl &= ~Twsiinten; /* stop further interrupts */ coherence(); intrclear(Irqlo, IRQ0twsi); } static void twsiinit(void) { Kwtwsi *krp = (Kwtwsi *)soc.twsi; intrenable(Irqlo, IRQ0twsi, interrupt, nil, "twsi"); krp->ctl &= ~Twsiint; krp->ctl |= Twsiinten; coherence(); } static void twsishutdown(void) { Kwtwsi *krp = (Kwtwsi *)soc.twsi; krp->ctl &= ~Twsiinten; coherence(); intrdisable(Irqlo, IRQ0twsi, interrupt, nil, "twsi"); } static Chan* twsiattach(char *param) { return devattach(L'²', param); } static Walkqid* twsiwalk(Chan *c, Chan *nc, char **name, int nname) { return devwalk(c, nc, name, nname, twsidir, nelem(twsidir), devgen); } static int twsistat(Chan *c, uchar *db, int n) { return devstat(c, db, n, twsidir, nelem(twsidir), devgen); } static Chan* twsiopen(Chan *c, int omode) { switch((ulong)c->qid.path){ default: error(Eperm); case Qdir: case Qtwsi: break; } c = devopen(c, omode, twsidir, nelem(twsidir), devgen); c->mode = openmode(omode); c->flag |= COPEN; c->offset = 0; return c; } static void twsiclose(Chan *) { } static long twsiread(Chan *c, void *v, long n, vlong off) { switch((ulong)c->qid.path){ default: error(Eperm); case Qdir: return devdirread(c, v, n, twsidir, nelem(twsidir), devgen); case Qtwsi: return twsixfer(v, n, off, twsidoread); } } static long twsiwrite(Chan *c, void *v, long n, vlong off) { switch((ulong)c->qid.path){ default: error(Eperm); case Qtwsi: return twsixfer(v, n, off, twsidowrite); } } Dev twsidevtab = { L'²', "twsi", devreset, twsiinit, twsishutdown, twsiattach, twsiwalk, twsistat, twsiopen, devcreate, twsiclose, twsiread, devbread, twsiwrite, devbwrite, devremove, devwstat, };