How to install RTC3231


#1

Hi, I am trying to use RTC DS3231 but doesn’t work I use BananaPro under

-Version-
Kernel                : Linux 3.4.103 (armv7l)
Compiled                : #4 SMP PREEMPT Thu Dec 18 12:55:58 CST 2014
C Library                : Unknown
Default C Compiler                : GNU C Compiler version 4.8.4 (Ubuntu/Linaro 4.8.4-2ubuntu1~14.04.3) 
Distribution                : Ubuntu 14.04.1 LTS


I attached RTC and did the following:

bananapi@lemaker:~$ i2cdetect -y 2
     0  1  2  3  4  5  6  7  8  9  a  b  c  d  e  f
00:          -- -- -- -- -- -- -- -- -- -- -- -- -- 
10: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
20: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
30: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
40: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
50: -- 51 52 53 54 55 56 57 -- -- -- -- -- -- -- -- 
60: -- -- -- -- -- -- -- -- 68 -- -- -- -- -- -- -- 
70: 70 -- 72 73 74 75 76 77               

I have several I2C-units attached which are working perfectly. 0x68 is the RTC Adress which is resonding under i2cget

Then I did 
bananapi@lemaker:~$ echo "ds3231 0x68" | sudo tee /sys/class/i2c-adapter/i2c-2/new_device
ds3231 0x68

bananapi@lemaker:~$ ls /sys/class/i2c-adapter/i2c-2
2-0068         device   name        power      uevent
delete_device  i2c-dev  new_device  subsystem

2-0068 is the newly ceated file

bananapi@lemaker:~$ cat /sys/class/i2c-adapter/i2c-2/2-0068/name
ds3231

bananapi@lemaker:~$ cat /sys/class/i2c-adapter/i2c-2/2-0068/uevent
MODALIAS=i2c:ds3231

bananapi@lemaker:~$ ls /sys/class/i2c-adapter/i2c-2/2-0068
modalias  name  power  subsystem  uevent

bananapi@lemaker:~$ cat /sys/class/i2c-adapter/i2c-2/2-0068/modalias
i2c:ds3231

bananapi@lemaker:~$ dmesg|grep ds3231
[  262.288400] i2c i2c-2: new_device: Instantiated device ds3231 at 0x68

bananapi@lemaker:~$ hwclock -r
hwclock: Cannot access the Hardware Clock via any known method.
hwclock: Use the --debug option to see the details of our search for an access method.

bananapi@lemaker:~$ hwclock --debug
hwclock von util-linux 2.20.1
hwclock: Konnte /dev/rtc nicht öffnen: Keine Berechtigung
Keine brauchbare Uhrschnittstelle gefunden.
hwclock: Cannot access the Hardware Clock via any known method.

/dev/rtc1 never appears

What iam missing ?