diff options
Diffstat (limited to 'Documentation/i2c/chips')
| -rw-r--r-- | Documentation/i2c/chips/eeprom | 96 | ||||
| -rw-r--r-- | Documentation/i2c/chips/max6875 | 108 |
2 files changed, 0 insertions, 204 deletions
diff --git a/Documentation/i2c/chips/eeprom b/Documentation/i2c/chips/eeprom deleted file mode 100644 index f7e8104..0000000 --- a/Documentation/i2c/chips/eeprom +++ /dev/null @@ -1,96 +0,0 @@ -Kernel driver eeprom -==================== - -Supported chips: - * Any EEPROM chip in the designated address range - Prefix: 'eeprom' - Addresses scanned: I2C 0x50 - 0x57 - Datasheets: Publicly available from: - Atmel (www.atmel.com), - Catalyst (www.catsemi.com), - Fairchild (www.fairchildsemi.com), - Microchip (www.microchip.com), - Philips (www.semiconductor.philips.com), - Rohm (www.rohm.com), - ST (www.st.com), - Xicor (www.xicor.com), - and others. - - Chip Size (bits) Address - 24C01 1K 0x50 (shadows at 0x51 - 0x57) - 24C01A 1K 0x50 - 0x57 (Typical device on DIMMs) - 24C02 2K 0x50 - 0x57 - 24C04 4K 0x50, 0x52, 0x54, 0x56 - (additional data at 0x51, 0x53, 0x55, 0x57) - 24C08 8K 0x50, 0x54 (additional data at 0x51, 0x52, - 0x53, 0x55, 0x56, 0x57) - 24C16 16K 0x50 (additional data at 0x51 - 0x57) - Sony 2K 0x57 - - Atmel 34C02B 2K 0x50 - 0x57, SW write protect at 0x30-37 - Catalyst 34FC02 2K 0x50 - 0x57, SW write protect at 0x30-37 - Catalyst 34RC02 2K 0x50 - 0x57, SW write protect at 0x30-37 - Fairchild 34W02 2K 0x50 - 0x57, SW write protect at 0x30-37 - Microchip 24AA52 2K 0x50 - 0x57, SW write protect at 0x30-37 - ST M34C02 2K 0x50 - 0x57, SW write protect at 0x30-37 - - -Authors: - Frodo Looijaard <frodol@dds.nl>, - Philip Edelbrock <phil@netroedge.com>, - Jean Delvare <khali@linux-fr.org>, - Greg Kroah-Hartman <greg@kroah.com>, - IBM Corp. - -Description ------------ - -This is a simple EEPROM module meant to enable reading the first 256 bytes -of an EEPROM (on a SDRAM DIMM for example). However, it will access serial -EEPROMs on any I2C adapter. The supported devices are generically called -24Cxx, and are listed above; however the numbering for these -industry-standard devices may vary by manufacturer. - -This module was a programming exercise to get used to the new project -organization laid out by Frodo, but it should be at least completely -effective for decoding the contents of EEPROMs on DIMMs. - -DIMMS will typically contain a 24C01A or 24C02, or the 34C02 variants. -The other devices will not be found on a DIMM because they respond to more -than one address. - -DDC Monitors may contain any device. Often a 24C01, which responds to all 8 -addresses, is found. - -Recent Sony Vaio laptops have an EEPROM at 0x57. We couldn't get the -specification, so it is guess work and far from being complete. - -The Microchip 24AA52/24LCS52, ST M34C02, and others support an additional -software write protect register at 0x30 - 0x37 (0x20 less than the memory -location). The chip responds to "write quick" detection at this address but -does not respond to byte reads. If this register is present, the lower 128 -bytes of the memory array are not write protected. Any byte data write to -this address will write protect the memory array permanently, and the -device will no longer respond at the 0x30-37 address. The eeprom driver -does not support this register. - -Lacking functionality: - -* Full support for larger devices (24C04, 24C08, 24C16). These are not -typically found on a PC. These devices will appear as separate devices at -multiple addresses. - -* Support for really large devices (24C32, 24C64, 24C128, 24C256, 24C512). -These devices require two-byte address fields and are not supported. - -* Enable Writing. Again, no technical reason why not, but making it easy -to change the contents of the EEPROMs (on DIMMs anyway) also makes it easy -to disable the DIMMs (potentially preventing the computer from booting) -until the values are restored somehow. - -Use: - -After inserting the module (and any other required SMBus/i2c modules), you -should have some EEPROM directories in /sys/bus/i2c/devices/* of names such -as "0-0050". Inside each of these is a series of files, the eeprom file -contains the binary data from EEPROM. diff --git a/Documentation/i2c/chips/max6875 b/Documentation/i2c/chips/max6875 deleted file mode 100644 index 10ca43c..0000000 --- a/Documentation/i2c/chips/max6875 +++ /dev/null @@ -1,108 +0,0 @@ -Kernel driver max6875 -===================== - -Supported chips: - * Maxim MAX6874, MAX6875 - Prefix: 'max6875' - Addresses scanned: None (see below) - Datasheet: - http://pdfserv.maxim-ic.com/en/ds/MAX6874-MAX6875.pdf - -Author: Ben Gardner <bgardner@wabtec.com> - - -Description ------------ - -The Maxim MAX6875 is an EEPROM-programmable power-supply sequencer/supervisor. -It provides timed outputs that can be used as a watchdog, if properly wired. -It also provides 512 bytes of user EEPROM. - -At reset, the MAX6875 reads the configuration EEPROM into its configuration -registers. The chip then begins to operate according to the values in the -registers. - -The Maxim MAX6874 is a similar, mostly compatible device, with more intputs -and outputs: - vin gpi vout -MAX6874 6 4 8 -MAX6875 4 3 5 - -See the datasheet for more information. - - -Sysfs entries -------------- - -eeprom - 512 bytes of user-defined EEPROM space. - - -General Remarks ---------------- - -Valid addresses for the MAX6875 are 0x50 and 0x52. -Valid addresses for the MAX6874 are 0x50, 0x52, 0x54 and 0x56. -The driver does not probe any address, so you must force the address. - -Example: -$ modprobe max6875 force=0,0x50 - -The MAX6874/MAX6875 ignores address bit 0, so this driver attaches to multiple -addresses. For example, for address 0x50, it also reserves 0x51. -The even-address instance is called 'max6875', the odd one is 'dummy'. - - -Programming the chip using i2c-dev ----------------------------------- - -Use the i2c-dev interface to access and program the chips. -Reads and writes are performed differently depending on the address range. - -The configuration registers are at addresses 0x00 - 0x45. -Use i2c_smbus_write_byte_data() to write a register and -i2c_smbus_read_byte_data() to read a register. -The command is the register number. - -Examples: -To write a 1 to register 0x45: - i2c_smbus_write_byte_data(fd, 0x45, 1); - -To read register 0x45: - value = i2c_smbus_read_byte_data(fd, 0x45); - - -The configuration EEPROM is at addresses 0x8000 - 0x8045. -The user EEPROM is at addresses 0x8100 - 0x82ff. - -Use i2c_smbus_write_word_data() to write a byte to EEPROM. - -The command is the upper byte of the address: 0x80, 0x81, or 0x82. -The data word is the lower part of the address or'd with data << 8. - cmd = address >> 8; - val = (address & 0xff) | (data << 8); - -Example: -To write 0x5a to address 0x8003: - i2c_smbus_write_word_data(fd, 0x80, 0x5a03); - - -Reading data from the EEPROM is a little more complicated. -Use i2c_smbus_write_byte_data() to set the read address and then -i2c_smbus_read_byte() or i2c_smbus_read_i2c_block_data() to read the data. - -Example: -To read data starting at offset 0x8100, first set the address: - i2c_smbus_write_byte_data(fd, 0x81, 0x00); - -And then read the data - value = i2c_smbus_read_byte(fd); - - or - - count = i2c_smbus_read_i2c_block_data(fd, 0x84, 16, buffer); - -The block read should read 16 bytes. -0x84 is the block read command. - -See the datasheet for more details. - |