ref: b9efa5bad11f7ada9416bab6f63ca4dd69b520c5
dir: /v1/9/i2c/bcm/devrtc7940x.c/
/*
* MCP7940x realtime clock (accessed via rtc)
*/
#include "u.h"
#include "../port/lib.h"
#include "mem.h"
#include "dat.h"
#include "fns.h"
#include "../port/error.h"
enum {
/* registers */
Seconds= 0,
Minutes= 1,
Hours= 2,
Weekday= 3,
Mday= 4,
Month= 5,
Year= 6,
Nbcd= 7,
/* Hours register may be in 12-hour or 24-hour mode */
Twelvehr= 0x40,
Pm= 0x20,
Start= 0x80,
Vbaten= 0x08,
I2Caddr= 0x6F,
};
typedef struct Rtc Rtc;
struct Rtc
{
int sec;
int min;
int hour;
int mday;
int mon;
int year;
};
enum{
Qdir = 0,
Qrtc,
};
Dirtab rtcdir[]={
".", {Qdir, 0, QTDIR}, 0, 0555,
"rtc", {Qrtc, 0}, 0, 0664,
};
static ulong rtc2sec(Rtc*);
static void sec2rtc(ulong, Rtc*);
static void
i2cread(uint addr, void *buf, int len)
{
I2Cdev d;
d.addr = addr;
d.tenbit = 0;
d.salen = 1;
i2crecv(&d, buf, len, 0);
}
static void
i2cwrite(uint addr, void *buf, int len)
{
I2Cdev d;
d.addr = addr;
d.tenbit = 0;
d.salen = 1;
i2csend(&d, buf, len, 0);
}
static void
rtcinit()
{
i2csetup(0);
}
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)
{
char dummy;
omode = openmode(omode);
switch((ulong)c->qid.path){
case Qrtc:
if(strcmp(up->user, eve)!=0 && omode!=OREAD)
error(Eperm);
/* if it's not there, this will throw an error */
i2cread(I2Caddr, &dummy, 1);
break;
}
return devopen(c, omode, rtcdir, nelem(rtcdir), devgen);
}
static void
rtcclose(Chan*)
{
}
static int
bcd(int n)
{
return (n & 0xF) + (10 * (n >> 4));
}
long
rtctime(void)
{
uchar clk[Nbcd];
Rtc rtc;
clk[0] = 0;
i2cwrite(I2Caddr, clk, 1);
i2cread(I2Caddr, clk, Nbcd);
/*
* convert from BCD
*/
rtc.sec = bcd(clk[Seconds] & 0x7F);
rtc.min = bcd(clk[Minutes] & 0x7F);
rtc.hour = bcd(clk[Hours] & 0x3F);
if(clk[Hours] & Twelvehr){
rtc.hour = bcd(clk[Hours] & 0x1F);
if(clk[Hours] & Pm)
rtc.hour += 12;
}
rtc.mday = bcd(clk[Mday] & 0x3F);
rtc.mon = bcd(clk[Month] & 0x1F);
rtc.year = bcd(clk[Year]);
/*
* the world starts jan 1 1970
*/
if(rtc.year < 70)
rtc.year += 2000;
else
rtc.year += 1900;
return rtc2sec(&rtc);
}
static long
rtcread(Chan* c, void* buf, long n, vlong off)
{
ulong t;
ulong offset = off;
if(c->qid.type & QTDIR)
return devdirread(c, buf, n, rtcdir, nelem(rtcdir), devgen);
switch((ulong)c->qid.path){
case Qrtc:
t = rtctime();
n = readnum(offset, buf, n, t, 12);
return n;
}
error(Ebadarg);
return 0;
}
#define PUTBCD(n,o) bcdclock[1+o] = (n % 10) | (((n / 10) % 10)<<4)
static long
rtcwrite(Chan* c, void* buf, long n, vlong off)
{
Rtc rtc;
ulong secs;
uchar bcdclock[1+Nbcd];
char *cp, *ep;
ulong offset = off;
if(offset!=0)
error(Ebadarg);
switch((ulong)c->qid.path){
case Qrtc:
/*
* read the time
*/
cp = ep = buf;
ep += n;
while(cp < ep){
if(*cp>='0' && *cp<='9')
break;
cp++;
}
secs = strtoul(cp, 0, 0);
/*
* convert to bcd
*/
sec2rtc(secs, &rtc);
PUTBCD(rtc.sec, Seconds);
PUTBCD(rtc.min, Minutes); /* forces 24 hour mode */
PUTBCD(rtc.hour, Hours);
PUTBCD(0, Weekday); /* hope no other OS uses this */
PUTBCD(rtc.mday, Mday);
PUTBCD(rtc.mon, Month);
PUTBCD(rtc.year, Year);
/*
* write the clock
*/
bcdclock[0] = 0;
bcdclock[1+Seconds] |= Start;
bcdclock[1+Weekday] |= Vbaten;
i2cwrite(I2Caddr, bcdclock, 1+Nbcd);
return n;
}
error(Ebadarg);
return 0;
}
Dev rtc7940xdevtab = {
'r',
"rtc",
devreset,
rtcinit,
devshutdown,
rtcattach,
rtcwalk,
rtcstat,
rtcopen,
devcreate,
rtcclose,
rtcread,
devbread,
rtcwrite,
devbwrite,
devremove,
devwstat,
};
#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;
}
/*
* 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;
return;
}