ref: f5cc6fbe3a7bcf8bdb002c646ddd519014afafd2
dir: /os/cerf405/devrtc.c/
/*
* DS1339 Timekeeper (on I2C)
*/
#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 Rtc Rtc;
typedef struct Rtcreg Rtcreg;
struct Rtc
{
int sec;
int min;
int hour;
int wday;
int mday;
int mon;
int year;
};
struct Rtcreg
{
uchar sec;
uchar min;
uchar hour;
uchar wday; /* 1=Sun */
uchar mday; /* 00-31 */
uchar mon; /* 1-12 */
uchar year;
};
enum{
Qdir = 0,
Qrtc,
Rtclen= 7, /* bytes read and written to timekeeper */
};
static QLock rtclock; /* mutex on nvram operations */
static I2Cdev rtdev;
static Dirtab rtcdir[]={
".", {Qdir, 0, QTDIR}, 0, DMDIR|0555,
"rtc", {Qrtc, 0}, 0, 0664,
};
static ulong rtc2sec(Rtc*);
static void sec2rtc(ulong, Rtc*);
static void setrtc(Rtc*);
static void
rtcreset(void)
{
rtdev.addr = 0x68;
rtdev.salen = 1;
i2csetup(1);
}
static Chan*
rtcattach(char *spec)
{
return devattach('r', spec);
}
static Walkqid*
rtcwalk(Chan *c, Chan *nc, char **name, int nname)
{
return devwalk(c, nc, name, nname, rtcdir, nelem(rtcdir), devgen);
}
static int
rtcstat(Chan *c, uchar *dp, int n)
{
return devstat(c, dp, n, rtcdir, nelem(rtcdir), devgen);
}
static Chan*
rtcopen(Chan *c, int omode)
{
omode = openmode(omode);
switch((ulong)c->qid.path){
case Qrtc:
if(strcmp(up->env->user, eve)!=0 && omode!=OREAD)
error(Eperm);
break;
}
return devopen(c, omode, rtcdir, nelem(rtcdir), devgen);
}
static void
rtcclose(Chan*)
{
}
static long
rtcread(Chan *c, void *buf, long n, vlong offset)
{
ulong t, ot;
if(c->qid.type & QTDIR)
return devdirread(c, buf, n, rtcdir, nelem(rtcdir), devgen);
switch((ulong)c->qid.path){
case Qrtc:
qlock(&rtclock);
t = rtctime();
do{
ot = t;
t = rtctime(); /* make sure there's no skew */
}while(t != ot);
qunlock(&rtclock);
return readnum(offset, buf, n, t, 12);
}
error(Egreg);
return -1; /* never reached */
}
static long
rtcwrite(Chan *c, void *buf, long n, vlong off)
{
Rtc rtc;
ulong secs;
char *cp, sbuf[32];
ulong offset = off;
switch((ulong)c->qid.path){
case Qrtc:
if(offset!=0 || n >= sizeof(sbuf)-1)
error(Ebadarg);
memmove(sbuf, buf, n);
sbuf[n] = '\0';
/*
* read the time
*/
cp = sbuf;
while(*cp){
if(*cp>='0' && *cp<='9')
break;
cp++;
}
secs = strtoul(cp, 0, 0);
/*
* convert to bcd
*/
sec2rtc(secs, &rtc);
/*
* write it
*/
setrtc(&rtc);
return n;
}
error(Egreg);
return -1; /* never reached */
}
Dev rtcdevtab = {
'r',
"rtc",
rtcreset,
devinit,
devshutdown,
rtcattach,
rtcwalk,
rtcstat,
rtcopen,
devcreate,
rtcclose,
rtcread,
devbread,
rtcwrite,
devbwrite,
devremove,
devwstat,
};
static int
getbcd(int bcd)
{
return (bcd&0x0f) + 10 * (bcd>>4);
}
static int
putbcd(int val)
{
return (val % 10) | (((val/10) % 10) << 4);
}
long
rtctime(void)
{
Rtc rtc;
Rtcreg d;
int h;
if(waserror()){
iprint("rtc: err %s\n", up->env->errstr);
return 0;
}
if(i2crecv(&rtdev, &d, Rtclen, 0) != Rtclen)
return 0;
poperror();
rtc.sec = getbcd(d.sec);
rtc.min = getbcd(d.min);
if(d.hour & (1<<6)){ /* 12 hour clock */
h = d.hour & 0x1F;
if(d.hour & (1<<5))
h += 0x12;
rtc.hour = getbcd(h);
}else
rtc.hour = getbcd(d.hour);
rtc.mday = getbcd(d.mday);
rtc.mon = getbcd(d.mon & 0x7f);
rtc.year = getbcd(d.year);
if(rtc.mon < 1 || rtc.mon > 12)
return 0;
if(d.mon & (1<<7))
rtc.year += 2000;
else
rtc.year += 1900;
return rtc2sec(&rtc);
}
static void
setrtc(Rtc *rtc)
{
Rtcreg d;
memset(&d, 0, sizeof(d));
d.year = putbcd(rtc->year % 100);
d.mon = putbcd(rtc->mon);
if(rtc->year >= 2000)
d.mon |= 1<<7;
d.wday = rtc->wday+1;
d.mday = putbcd(rtc->mday);
d.hour = putbcd(rtc->hour);
d.min = putbcd(rtc->min);
d.sec = putbcd(rtc->sec);
i2csend(&rtdev, &d, Rtclen, 0);
}
#define SEC2MIN 60L
#define SEC2HOUR (60L*SEC2MIN)
#define SEC2DAY (24L*SEC2HOUR)
/*
* days per month plus days/year
*/
static int dmsize[] =
{
365, 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31
};
static int ldmsize[] =
{
366, 31, 29, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31
};
/*
* return the days/month for the given year
*/
static int *
yrsize(int y)
{
if((y%4) == 0 && ((y%100) != 0 || (y%400) == 0))
return ldmsize;
else
return dmsize;
}
/*
* compute seconds since Jan 1 1970
*/
static ulong
rtc2sec(Rtc *rtc)
{
ulong secs;
int i;
int *d2m;
secs = 0;
/*
* seconds per year
*/
for(i = 1970; i < rtc->year; i++){
d2m = yrsize(i);
secs += d2m[0] * SEC2DAY;
}
/*
* seconds per month
*/
d2m = yrsize(rtc->year);
for(i = 1; i < rtc->mon; i++)
secs += d2m[i] * SEC2DAY;
secs += (rtc->mday-1) * SEC2DAY;
secs += rtc->hour * SEC2HOUR;
secs += rtc->min * SEC2MIN;
secs += rtc->sec;
return secs;
}
/*
* compute rtc from seconds since Jan 1 1970
*/
static void
sec2rtc(ulong secs, Rtc *rtc)
{
int d;
long hms, day;
int *d2m;
/*
* break initial number into days
*/
hms = secs % SEC2DAY;
day = secs / SEC2DAY;
if(hms < 0) {
hms += SEC2DAY;
day -= 1;
}
/*
* day is the day number.
* generate day of the week.
* The addend is 4 mod 7 (1/1/1970 was Thursday)
*/
rtc->wday = (day + 7340036L) % 7;
/*
* generate hours:minutes:seconds
*/
rtc->sec = hms % 60;
d = hms / 60;
rtc->min = d % 60;
d /= 60;
rtc->hour = d;
/*
* year number
*/
if(day >= 0)
for(d = 1970; day >= *yrsize(d); d++)
day -= *yrsize(d);
else
for (d = 1970; day < 0; d--)
day += *yrsize(d-1);
rtc->year = d;
/*
* generate month
*/
d2m = yrsize(rtc->year);
for(d = 1; day >= d2m[d]; d++)
day -= d2m[d];
rtc->mday = day + 1;
rtc->mon = d;
}