Realtime Clock (RTC DS1307) am Raspberry Pi betreiben

pi@rasp ~ $ echo ds1307 0x68 > /sys/class/i2c-adapter/i2c-1/new_device
-bash: /sys/class/i2c-adapter/i2c-1/new_device: Permission denied
pi@rasp ~ $ sudo echo ds1307 0x68 > /sys/class/i2c-adapter/i2c-1/new_device
-bash: /sys/class/i2c-adapter/i2c-1/new_device: Permission denied
pi@rasp ~ $ su root
Password:
root@rasp:/home/pi# echo ds1307 0x68 > /sys/class/i2c-adapter/i2c-1/new_device
root@rasp:/home/pi# hwclock -r
Sat Jan  1 01:00:12 2000  -0.618320 seconds
root@rasp:/home/pi# hwclock -w
root@rasp:/home/pi# hwclock -r
Wed Jan 22 12:36:08 2014  -0.587390 seconds
root@rasp:/home/pi# nano /etc/rc.local
root@rasp:/home/pi# hwclock -s
root@rasp:/home/pi# sudo echo ds1307 0x68 > /sys/class/i2c-adapter/i2c-1/new_device
echo: write error: Invalid argument
root@rasp:/home/pi# echo ds1307 0x68 > /sys/class/i2c-adapter/i2c-1/new_device  bash: echo: write error: Invalid argument
root@rasp:/home/pi# reboot

pi@bastelPI ~ $ ./eeprom -h
./eeprom [-d dev] [-a adr] [-p pgs] [-w] [-y] [-f file]
	dev: device, e.g. /dev/i2c-0    (def)
	adr: base address of eeprom, eg 0xA0 (def)
	pgs: number of pages to read, eg 8 (def)
	-w : write to eeprom (default is reading!)
	-y : suppress warning when writing (default is to warn!)
	-f file: copy eeprom contents to/from file
	         (default for read is test only; for write is all zeros)
Note on pages/addresses:
	eeproms with more than 256 byte appear as if they
	were several eeproms with consecutive addresses on the bus
	so we might as well address several separate eeproms with
	increasing addresses....

pi@bastelPI ~ $ sudo nano ./data
pi@bastelPI ~ $ sudo ./eeprom -a 0x50 -p 0x01 -w  -y -f ./data
base-address of eeproms       : 0x50
number of pages to read       : 0 (0x50 .. 0x4f)
file opened for reading       : ./data
            on filedescriptor : 3
i2c-devicenode is             : /dev/i2c-0
            on filedescriptor : 4


pi@bastelPI ~ $ sudo ./eeprom -a 0x50 -p 0x01 -f ./data
base-address of eeproms       : 0x50
number of pages to read       : 0 (0x50 .. 0x4f)
file opened for writing       : ./data
            on filedescriptor : 3
i2c-devicenode is             : /dev/i2c-0
            on filedescriptor : 4


pi@bastelPI ~ $

pi@bastelPI ~ $ sudo i2cdetect 1
WARNING! This program can confuse your I2C bus, cause data loss and worse!
I will probe file /dev/i2c-1.
I will probe address range 0x03-0x77.
Continue? [Y/n] y
     0  1  2  3  4  5  6  7  8  9  a  b  c  d  e  f
00:          -- -- -- -- -- -- -- -- -- -- -- -- -- 
10: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
20: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
30: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
40: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
50: 50 -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
60: -- -- -- -- -- -- -- -- UU -- -- -- -- -- -- -- 
70: -- -- -- -- -- -- -- --                         
pi@bastelPI ~ $

http://www.lm-sensors.org/browser/i2c-tools/trunk/eepromer/eeprom.c


// schnipsel
23	#define DEFAULT_I2C_BUS      "/dev/i2c-0"
24	#define DEFAULT_EEPROM_ADDR  0x50         /* the 24C16 sits on i2c address 0x50 */
25	#define DEFAULT_NUM_PAGES    8            /* we default to a 24C16 eeprom which has 8 pages */
26	#define BYTES_PER_PAGE       256          /* one eeprom page is 256 byte */
27	#define MAX_BYTES            8            /* max number of bytes to write in one chunk */
28	       /* ... note: 24C02 and 24C01 only allow 8 bytes to be written in one chunk.   *
29	        *  if you are going to write 24C04,8,16 you can change this to 16            */
.
.
50	        if(len+offset >256){
// schnipsel

http://www.lm-sensors.org/browser/i2c-tools/trunk/eepromer/eeprom.c


// schnipsel
23	#define DEFAULT_I2C_BUS      "/dev/i2c-1"  // weil das auf Bus 1 liegt
24	#define DEFAULT_EEPROM_ADDR  0x50         /* the 24C16 sits on i2c address 0x50 */
25	#define DEFAULT_NUM_PAGES    256            /* we default to a 24C16 eeprom which has 8 pages */
26	#define BYTES_PER_PAGE       32          /* one eeprom page is 256 byte */
27	#define MAX_BYTES            32            /* max number of bytes to write in one chunk */
28	       /* ... note: 24C02 and 24C01 only allow 8 bytes to be written in one chunk.   *
29	        *  if you are going to write 24C04,8,16 you can change this to 16            */
.
.
50	        if(len+offset >256){
// schnipsel

/*
This program is hereby placed into the public domain.
Of course the program is provided without warranty of any kind.
*/
#include <sys/ioctl.h>
#include <errno.h>
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <fcntl.h>
#include <string.h>
#include <time.h>
#include <linux/i2c.h>
#include <linux/i2c-dev.h>


/*
  this program can read 24C16 (and probably smaller ones, too)
  I wrote it as a quick and dirty hack because my satellite receiver
  hung again... so I had to reprogram the eeprom where is stores it's
  settings.
 */


#define DEFAULT_I2C_BUS      "/dev/i2c-1"
#define DEFAULT_EEPROM_ADDR  0x50         /* the 24C16 sits on i2c address 0x50 */
#define DEFAULT_NUM_PAGES    256            /* we default to a 24C32 --16-- eeprom which has 8 pages */
#define BYTES_PER_PAGE       32          /* one eeprom page is 256 byte */
#define MAX_BYTES            32            /* max number of bytes to write in one chunk */
       /* ... note: 24C02 and 24C01 only allow 8 bytes to be written in one chunk.   *
        *  if you are going to write 24C04,8,16 you can change this to 16            */


/* write len bytes (stored in buf) to eeprom at address addr, page-offset offset */
/* if len=0 (buf may be NULL in this case) you can reposition the eeprom's read-pointer */
/* return 0 on success, -1 on failure */
int eeprom_write(int fd,
		 unsigned int addr,
		 unsigned int offset,
		 unsigned char *buf,
		 unsigned char len
){
	struct i2c_rdwr_ioctl_data msg_rdwr;
	struct i2c_msg             i2cmsg;
	int i;
	char _buf[MAX_BYTES + 1];


	if(len>MAX_BYTES){
	    fprintf(stderr,"I can only write MAX_BYTES bytes at a time!\n");
	    return -1;
	}


	if(len+offset >BYTES_PER_PAGE){
	    fprintf(stderr,"Sorry, len(%d)+offset(%d) > BYTES_PER_PAGE (page boundary)\n",
			len,offset);
	    return -1;
	}


	_buf[0]=offset;    /* _buf[0] is the offset into the eeprom page! */
	for(i=0;i<len;i++) /* copy buf[0..n] -> _buf[1..n+1] */
	    _buf[1+i]=buf[i];


	msg_rdwr.msgs = &i2cmsg;
	msg_rdwr.nmsgs = 1;


	i2cmsg.addr  = addr;
	i2cmsg.flags = 0;
	i2cmsg.len   = 1+len;
	i2cmsg.buf   = _buf;


	if((i=ioctl(fd,I2C_RDWR,&msg_rdwr))<0){
	    perror("ioctl()");
	    fprintf(stderr,"ioctl returned %d\n",i);
	    return -1;
	}


	if(len>0)
	    fprintf(stderr,"Wrote %d bytes to eeprom at 0x%02x, offset %08x\n",
		    len,addr,offset);
	else
	    fprintf(stderr,"Positioned pointer in eeprom at 0x%02x to offset %08x\n",
		    addr,offset);


	return 0;
}


/* read len bytes stored in eeprom at address addr, offset offset in array buf */
/* return -1 on error, 0 on success */
int eeprom_read(int fd,
		 unsigned int addr,
		 unsigned int offset,
		 unsigned char *buf,
		 unsigned char len
){
	struct i2c_rdwr_ioctl_data msg_rdwr;
	struct i2c_msg             i2cmsg;
	int i;


	if(len>MAX_BYTES){
	    fprintf(stderr,"I can only write MAX_BYTES bytes at a time!\n");
	    return -1;
	}


	if(eeprom_write(fd,addr,offset,NULL,0)<0)
	    return -1;


	msg_rdwr.msgs = &i2cmsg;
	msg_rdwr.nmsgs = 1;


	i2cmsg.addr  = addr;
	i2cmsg.flags = I2C_M_RD;
	i2cmsg.len   = len;
	i2cmsg.buf   = buf;


	if((i=ioctl(fd,I2C_RDWR,&msg_rdwr))<0){
	    perror("ioctl()");
	    fprintf(stderr,"ioctl returned %d\n",i);
	    return -1;
	}


	fprintf(stderr,"Read %d bytes from eeprom at 0x%02x, offset %08x\n",
		len,addr,offset);


	return 0;
}






int main(int argc, char **argv){
    int i,j;


    /* filedescriptor and name of device */
    int d; 
    char *dn=DEFAULT_I2C_BUS;


    /* filedescriptor and name of data file */
    int f=-1;
    char *fn=NULL;


    unsigned int addr=DEFAULT_EEPROM_ADDR;
    int rwmode=0;
    int pages=DEFAULT_NUM_PAGES;


    int force=0; /* suppress warning on write! */

    while((i=getopt(argc,argv,"d:a:p:wyf:h"))>=0){
	switch(i){
	case 'h':
	    fprintf(stderr,"%s [-d dev] [-a adr] [-p pgs] [-w] [-y] [-f file]\n",argv[0]);
	    fprintf(stderr,"\tdev: device, e.g. /dev/i2c-0    (def)\n");
	    fprintf(stderr,"\tadr: base address of eeprom, eg 0xA0 (def)\n");
	    fprintf(stderr,"\tpgs: number of pages to read, eg 8 (def)\n");
	    fprintf(stderr,"\t-w : write to eeprom (default is reading!)\n");
	    fprintf(stderr,"\t-y : suppress warning when writing (default is to warn!)\n");
	    fprintf(stderr,"\t-f file: copy eeprom contents to/from file\n");
	    fprintf(stderr,"\t         (default for read is test only; for write is all zeros)\n");
	    fprintf(stderr,"Note on pages/addresses:\n");
	    fprintf(stderr,"\teeproms with more than 256 byte appear as if they\n");
	    fprintf(stderr,"\twere several eeproms with consecutive addresses on the bus\n");
	    fprintf(stderr,"\tso we might as well address several separate eeproms with\n");
	    fprintf(stderr,"\tincreasing addresses....\n\n");
	    exit(1);
	    break;
	case 'd':
	    dn=optarg;
	    break;
	case 'a':
	    if(sscanf(optarg,"0x%x",&addr)!=1){
		fprintf(stderr,"Cannot parse '%s' as addrs., example: 0xa0\n",
			optarg);
		exit(1);
	    }
	    break;
	case 'p':
	    if(sscanf(optarg,"%d",&pages)!=1){
		fprintf(stderr,"Cannot parse '%s' as number of pages, example: 8\n",
			optarg);
		exit(1);
	    }
	    break;
	case 'w':
	    rwmode++;
	    break;
	case 'f':
	    fn=optarg;
	    break;
	case 'y':
	    force++;
	    break;
	}


    }

    fprintf(stderr,"base-address of eeproms       : 0x%02x\n",addr);
    fprintf(stderr,"number of pages to read       : %d (0x%02x .. 0x%02x)\n",
		    pages,addr,addr+pages-1);


    if(fn){
	if(!rwmode) /* if we are reading, *WRITE* to file */
	    f=open(fn,O_WRONLY|O_CREAT,0666);
	else /* if we are writing to eeprom, *READ* from file */
	    f=open(fn,O_RDONLY);
	if(f<0){
	    fprintf(stderr,"Could not open data-file %s for reading or writing\n",fn);
	    perror(fn);
	    exit(1);
	}
	fprintf(stderr,"file opened for %7s       : %s\n",rwmode?"reading":"writing",fn);
	fprintf(stderr,"            on filedescriptor : %d\n",f);
    }


    if((d=open(dn,O_RDWR))<0){
	fprintf(stderr,"Could not open i2c at %s\n",dn);
	perror(dn);
	exit(1);
    }


    fprintf(stderr,"i2c-devicenode is             : %s\n",dn);
    fprintf(stderr,"            on filedescriptor : %d\n\n",d);


    /***
     *** I'm not the one to blame of you screw your computer!
     ***/
    if(rwmode && ! force){
	unsigned char warnbuf[4];
	fprintf(stderr,"**WARNING**\n");
	fprintf(stderr," - \tYou have chosen to WRITE to this eeprom.\n");
	fprintf(stderr,"\tMake sure that this tiny chip is *NOT* vital to the\n");
	fprintf(stderr,"\toperation of your computer as you can easily corrupt\n");
	fprintf(stderr,"\tthe configuration memory of your SDRAM-memory-module,\n");
	fprintf(stderr,"\tyour IBM ThinkPad or whatnot...! Fixing these errors can be\n");
	fprintf(stderr,"\ta time-consuming and very costly process!\n\n");
	fprintf(stderr,"Things to consider:\n");
	fprintf(stderr," - \tYou can have more than one i2c-bus, check in /proc/bus/i2c\n");
	fprintf(stderr,"\tand specify the correct one with -d\n");
	fprintf(stderr,"\tright now you have chosen to use '%s'\n",dn);
	fprintf(stderr," - \tA eeprom can occupy several i2c-addresses (one per page)\n");
	fprintf(stderr,"\tso please make sure that there is no vital eeprom in your computer\n");
	fprintf(stderr,"\tsitting at addresses between 0x%02x and 0x%02x\n",addr,addr+pages-1);


	fprintf(stderr,"Enter 'yes' to continue:");
	fflush(stderr);
	if(!fgets(warnbuf,sizeof(warnbuf),stdin)){
	    fprintf(stderr,"\nCould not read confirmation from stdin!\n");
	    exit(1);
	}
	if(strncmp(warnbuf,"yes",3)){
	    fprintf(stderr,"\n** ABORTING WRITE! **, you did not answer 'yes'\n");
	    exit(1);
	}
    }


    for(i=0;i<pages;i++){
	unsigned char buf[BYTES_PER_PAGE];


	if(rwmode){


	    if(f>=0){
		j=read(f,buf,sizeof(buf));
		if(j<0){
		    fprintf(stderr,"Cannot read from file '%s'\n",fn);
		    perror(fn);
		    exit(1);
		}
		if(j!=sizeof(buf)){
		    fprintf(stderr,"File '%s' is too small, padding eeprom with zeroes\n",fn);
		    while(j<sizeof(buf))
			buf[j++]=0;
		}
	    } else {
		for(j=0;j<sizeof(buf);j++)
		    buf[j]=0;
	    }
            for(j=0;j<(BYTES_PER_PAGE/MAX_BYTES);j++)
		if(eeprom_write(d,addr+i,j*MAX_BYTES,buf+(j*MAX_BYTES),MAX_BYTES)<0)
		    exit(1);
	} else {
            for(j=0;j<(BYTES_PER_PAGE/MAX_BYTES);j++)
		if(eeprom_read(d,addr+i,j*MAX_BYTES,buf+(j*MAX_BYTES),MAX_BYTES)<0)
		    exit(1);
	}




	if(!rwmode && f>=0){
	    j=write(f,buf,sizeof(buf));
	    if(j!=sizeof(buf)){
		fprintf(stderr,"Cannot write to file '%s'\n",fn);
		perror(fn);
		exit(1);
	    }
	}


    }


    if(f>=0)
	close(f);


    close(d);


    exit(0);


}