projects / linux-2.6-block.git / blame
| Commit | Line | Data |
|---|---|---|
| fbf7f7b4 MF |
1 | Kernel driver w1_ds28e04 |
| 2 | ======================== | |
| 3 | ||
| 4 | Supported chips: | |
| 5 | * Maxim DS28E04-100 4096-Bit Addressable 1-Wire EEPROM with PIO | |
| 6 | ||
| 7 | supported family codes: | |
| 8 | W1_FAMILY_DS28E04 0x1C | |
| 9 | ||
| 10 | Author: Markus Franke, <franke.m@sebakmt.com> <franm@hrz.tu-chemnitz.de> | |
| 11 | ||
| 12 | Description | |
| 13 | ----------- | |
| 14 | ||
| 15 | Support is provided through the sysfs files "eeprom" and "pio". CRC checking | |
| 16 | during memory accesses can optionally be enabled/disabled via the device | |
| 17 | attribute "crccheck". The strong pull-up can optionally be enabled/disabled | |
| 18 | via the module parameter "w1_strong_pullup". | |
| 19 | ||
| 20 | Memory Access | |
| 21 | ||
| 22 | A read operation on the "eeprom" file reads the given amount of bytes | |
| 23 | from the EEPROM of the DS28E04. | |
| 24 | ||
| 25 | A write operation on the "eeprom" file writes the given byte sequence | |
| 26 | to the EEPROM of the DS28E04. If CRC checking mode is enabled only | |
| 27 | fully alligned blocks of 32 bytes with valid CRC16 values (in bytes 30 | |
| 28 | and 31) are allowed to be written. | |
| 29 | ||
| 30 | PIO Access | |
| 31 | ||
| 32 | The 2 PIOs of the DS28E04-100 are accessible via the "pio" sysfs file. | |
| 33 | ||
| 34 | The current status of the PIO's is returned as an 8 bit value. Bit 0/1 | |
| 35 | represent the state of PIO_0/PIO_1. Bits 2..7 do not care. The PIO's are | |
| 36 | driven low-active, i.e. the driver delivers/expects low-active values. |