harvey/sys/src/9/bcm/devarch.c

#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 = 0,
	Qbase,

	Qmax = 16,
};

typedef long Rdwrfn(Chan*, void*, long, vlong);

static Rdwrfn *readfn[Qmax];
static Rdwrfn *writefn[Qmax];

static Dirtab archdir[Qmax] = {
	".",		{ Qdir, 0, QTDIR },	0,	0555,
};

Lock archwlock;	/* the lock is only for changing archdir */
int narchdir = Qbase;

/*
 * Add a file to the #P listing.  Once added, you can't delete it.
 * You can't add a file with the same name as one already there,
 * and you get a pointer to the Dirtab entry so you can do things
 * like change the Qid version.  Changing the Qid path is disallowed.
 */
Dirtab*
addarchfile(char *name, int perm, Rdwrfn *rdfn, Rdwrfn *wrfn)
{
	int i;
	Dirtab d;
	Dirtab *dp;

	memset(&d, 0, sizeof d);
	strcpy(d.name, name);
	d.perm = perm;

	lock(&archwlock);
	if(narchdir >= Qmax){
		unlock(&archwlock);
		return nil;
	}

	for(i=0; i<narchdir; i++)
		if(strcmp(archdir[i].name, name) == 0){
			unlock(&archwlock);
			return nil;
		}

	d.qid.path = narchdir;
	archdir[narchdir] = d;
	readfn[narchdir] = rdfn;
	writefn[narchdir] = wrfn;
	dp = &archdir[narchdir++];
	unlock(&archwlock);

	return dp;
}

static Chan*
archattach(char* spec)
{
	return devattach('P', spec);
}

Walkqid*
archwalk(Chan* c, Chan *nc, char** name, int nname)
{
	return devwalk(c, nc, name, nname, archdir, narchdir, devgen);
}

static int
archstat(Chan* c, uchar* dp, int n)
{
	return devstat(c, dp, n, archdir, narchdir, devgen);
}

static Chan*
archopen(Chan* c, int omode)
{
	return devopen(c, omode, archdir, narchdir, devgen);
}

static void
archclose(Chan*)
{
}

static long
archread(Chan *c, void *a, long n, vlong offset)
{
	Rdwrfn *fn;

	switch((ulong)c->qid.path){
	case Qdir:
		return devdirread(c, a, n, archdir, narchdir, devgen);

	default:
		if(c->qid.path < narchdir && (fn = readfn[c->qid.path]))
			return fn(c, a, n, offset);
		error(Eperm);
		break;
	}

	return 0;
}

static long
archwrite(Chan *c, void *a, long n, vlong offset)
{
	Rdwrfn *fn;

	if(c->qid.path < narchdir && (fn = writefn[c->qid.path]))
		return fn(c, a, n, offset);
	error(Eperm);

	return 0;
}

void archinit(void);

Dev archdevtab = {
	'P',
	"arch",

	devreset,
	archinit,
	devshutdown,
	archattach,
	archwalk,
	archstat,
	archopen,
	devcreate,
	archclose,
	archread,
	devbread,
	archwrite,
	devbwrite,
	devremove,
	devwstat,
};

static long
cputyperead(Chan*, void *a, long n, vlong offset)
{
	char str[128];

	snprint(str, sizeof str, "ARM11 %d\n", m->cpumhz);
	return readstr(offset, a, n, str);
}

void
archinit(void)
{
	addarchfile("cputype", 0444, cputyperead, nil);
}