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What: /sys/bus/i2c/devices/<busnum>-<primary-addr>/unlock
Date: 2025-07-04
KernelVersion: 6.17
Contact: Abd-Alrhman Masalkhi <abd.masalkhi@gmail.com>
Description:
Write-only attribute used to present a password and unlock
access to protected areas of the M24LR chip, including
configuration registers such as the Sector Security Status
(SSS) bytes. A valid password must be written to enable write
access to these regions via the I2C interface.
Format:
- Hexadecimal string representing a 32-bit (4-byte) password
- Accepts 1 to 8 hex digits (e.g., "c", "1F", "a1b2c3d4")
- No "0x" prefix, whitespace, or trailing newline
- Case-insensitive
Behavior:
- If the password matches the internal stored value,
access to protected memory/configuration is granted
- If the password does not match the internally stored value,
it will fail silently
What: /sys/bus/i2c/devices/<busnum>-<primary-addr>/new_pass
Date: 2025-07-04
KernelVersion: 6.17
Contact: Abd-Alrhman Masalkhi <abd.masalkhi@gmail.com>
Description:
Write-only attribute used to update the password required to
unlock the M24LR chip.
Format:
- Hexadecimal string representing a new 32-bit password
- Accepts 1 to 8 hex digits (e.g., "1A", "ffff", "c0ffee00")
- No "0x" prefix, whitespace, or trailing newline
- Case-insensitive
Behavior:
- Overwrites the current password stored in the I2C password
register
- Requires the device to be unlocked before changing the
password
- If the device is locked, the write silently fails
What: /sys/bus/i2c/devices/<busnum>-<primary-addr>/uid
Date: 2025-07-04
KernelVersion: 6.17
Contact: Abd-Alrhman Masalkhi <abd.masalkhi@gmail.com>
Description:
Read-only attribute that exposes the 8-byte unique identifier
programmed into the M24LR chip at the factory.
Format:
- Lowercase hexadecimal string representing a 64-bit value
- 1 to 16 hex digits (e.g., "e00204f12345678")
- No "0x" prefix
- Includes a trailing newline
What: /sys/bus/i2c/devices/<busnum>-<primary-addr>/total_sectors
Date: 2025-07-04
KernelVersion: 6.17
Contact: Abd-Alrhman Masalkhi <abd.masalkhi@gmail.com>
Description:
Read-only attribute that exposes the total number of EEPROM
sectors available in the M24LR chip.
Format:
- 1 to 2 hex digits (e.g. "F")
- No "0x" prefix
- Includes a trailing newline
Notes:
- Value is encoded by the chip and corresponds to the EEPROM
size (e.g., 3 = 4 kbit for M24LR04E-R)
What: /sys/bus/i2c/devices/<busnum>-<primary-addr>/sss
Date: 2025-07-04
KernelVersion: 6.17
Contact: Abd-Alrhman Masalkhi <abd.masalkhi@gmail.com>
Description:
Read/write binary attribute representing the Sector Security
Status (SSS) bytes for all EEPROM sectors in STMicroelectronics
M24LR chips.
Each EEPROM sector has one SSS byte, which controls I2C and
RF access through protection bits and optional password
authentication.
Format:
- The file contains one byte per EEPROM sector
- Byte at offset N corresponds to sector N
- Binary access only; use tools like dd, Python, or C that
support byte-level I/O and offset control.
Notes:
- The number of valid bytes in this file is equal to the
value exposed by 'total_sectors' file
- Write access requires prior password authentication in
I2C mode
- Refer to the M24LR datasheet for full SSS bit layout
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