Environment : x86 / Ubuntu 14.04
I want obtain something similar to
&i2c0 {
eeprom: eeprom@50 {
compatible = "at,24c32";
reg = <0x50>;
};
};
But because in x86 no Device Tree is available, I am follow i2c/instantiating-device
document in the Linux kernel and use "Method 4: Instantiate from user-space".
Process to instantiate:
- Load at24 driver
- Load i2c-dev driver
Instantiate:
# echo eeprom 0x50 > /sys/bus/i2c/devices/i2c-0/new_device
Response from kernel in dmesg:
i2c i2c-0: new_device: Instantiated device eeprom at 0x50
A directory is created "0-0050". Found in /sys/bus/i2c/devices/i2c-0/0-0050
- This directory contains several files, but there is no file called "eeprom" in it.
Why the "eeprom" files are not created?
P.S:
The directory contains:
root@peio-t52r:~/etxoh# ls -la /sys/bus/i2c/devices/i2c-0/0-0050
total 0
drwxr-xr-x 3 root root 0 sep 25 15:06 .
drwxr-xr-x 5 root root 0 sep 25 14:48 ..
-r--r--r-- 1 root root 4096 sep 25 15:06 modalias
-r--r--r-- 1 root root 4096 sep 25 15:06 name
drwxr-xr-x 2 root root 0 sep 25 15:06 power
lrwxrwxrwx 1 root root 0 sep 25 15:06 subsystem -> ../../../../../bus/i2c
-rw-r--r-- 1 root root 4096 sep 25 15:06 uevent
And file "name" contains:
root@peio-t52r:~/etxoh# cat /sys/bus/i2c/devices/i2c-0/0-0050/name
eeprom
Use "24c32" instead of "eeprom" when instantiate I2C devices.
# echo 24c32 0x50 > /sys/bus/i2c/devices/i2c-0/new_device
In my board with AT24C02 SPD EEPROM, instantiate AT24C02 on bus 2
# echo 24c02 0x50 > /sys/class/i2c-adapter/i2c-2/new_device
The kernel message shows
[21230.868376] at24 2-0050: 256 byte 24c02 EEPROM, writable, 1 bytes/write
[21230.868423] i2c i2c-2: new_device: Instantiated device 24c02 at 0x50
The directory contains
root@:/sys/bus/i2c/devices/i2c-2/2-0050# ls
2-00500/ driver@ eeprom modalias name power/ subsystem@ uevent
The eeprom file is
root@:/sys/bus/i2c/devices/i2c-2/2-0052# hexdump -C eeprom
00000000 23 11 0c 03 45 21 00 08 00 60 00 03 02 03 00 00 |#...E!...`......|
00000010 00 00 07 0d f8 0f 00 00 6e 6e 6e 11 00 6e f0 0a |........nnn..n..|
00000020 20 08 00 05 00 f0 2b 34 28 00 78 00 14 3c 00 00 | .....+4(.x..<..|
00000030 00 00 00 00 00 00 00 00 00 00 00 00 16 36 0b 35 |.............6.5|
00000040 16 36 0b 35 00 00 16 36 0b 35 16 36 0b 35 00 00 |.6.5...6.5.6.5..|
00000050 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |................|
*
00000070 00 00 00 00 00 00 9c b5 00 00 00 00 e7 d6 0b e3 |................|
00000080 0f 11 02 00 00 00 00 00 00 00 00 00 00 00 00 00 |................|
00000090 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |................|
*
000000f0 00 00 00 00 00 00 00 00 00 00 00 00 00 00 db 08 |................|
00000100