aboutsummaryrefslogtreecommitdiffstats
path: root/Documentation/i2c
diff options
context:
space:
mode:
authorJean Delvare <khali@linux-fr.org>2009-10-04 16:53:40 -0400
committerJean Delvare <khali@linux-fr.org>2009-10-04 16:53:40 -0400
commitf546c65cd59275c7b95eba4f9b3ab83b38a5e9cb (patch)
treee8957c44efeb5f331272d092cab974679fa896c8 /Documentation/i2c
parent8a0382f6fceaf0c6479e582e1054f36333ea3d24 (diff)
i2c: Move misc devices documentation
Some times ago the eeprom and max6875 drivers moved to drivers/misc/eeprom, but their documentation did not follow. It's finally time to get rid of Documentation/i2c/chips. Signed-off-by: Jean Delvare <khali@linux-fr.org> Cc: Ben Gardner <gardner.ben@gmail.com> Acked-by: Wolfram Sang <w.sang@pengutronix.de>
Diffstat (limited to 'Documentation/i2c')
-rw-r--r--Documentation/i2c/chips/eeprom96
-rw-r--r--Documentation/i2c/chips/max6875108
2 files changed, 0 insertions, 204 deletions
diff --git a/Documentation/i2c/chips/eeprom b/Documentation/i2c/chips/eeprom
deleted file mode 100644
index f7e8104b576..00000000000
--- a/Documentation/i2c/chips/eeprom
+++ /dev/null
@@ -1,96 +0,0 @@
1Kernel driver eeprom
2====================
3
4Supported chips:
5 * Any EEPROM chip in the designated address range
6 Prefix: 'eeprom'
7 Addresses scanned: I2C 0x50 - 0x57
8 Datasheets: Publicly available from:
9 Atmel (www.atmel.com),
10 Catalyst (www.catsemi.com),
11 Fairchild (www.fairchildsemi.com),
12 Microchip (www.microchip.com),
13 Philips (www.semiconductor.philips.com),
14 Rohm (www.rohm.com),
15 ST (www.st.com),
16 Xicor (www.xicor.com),
17 and others.
18
19 Chip Size (bits) Address
20 24C01 1K 0x50 (shadows at 0x51 - 0x57)
21 24C01A 1K 0x50 - 0x57 (Typical device on DIMMs)
22 24C02 2K 0x50 - 0x57
23 24C04 4K 0x50, 0x52, 0x54, 0x56
24 (additional data at 0x51, 0x53, 0x55, 0x57)
25 24C08 8K 0x50, 0x54 (additional data at 0x51, 0x52,
26 0x53, 0x55, 0x56, 0x57)
27 24C16 16K 0x50 (additional data at 0x51 - 0x57)
28 Sony 2K 0x57
29
30 Atmel 34C02B 2K 0x50 - 0x57, SW write protect at 0x30-37
31 Catalyst 34FC02 2K 0x50 - 0x57, SW write protect at 0x30-37
32 Catalyst 34RC02 2K 0x50 - 0x57, SW write protect at 0x30-37
33 Fairchild 34W02 2K 0x50 - 0x57, SW write protect at 0x30-37
34 Microchip 24AA52 2K 0x50 - 0x57, SW write protect at 0x30-37
35 ST M34C02 2K 0x50 - 0x57, SW write protect at 0x30-37
36
37
38Authors:
39 Frodo Looijaard <frodol@dds.nl>,
40 Philip Edelbrock <phil@netroedge.com>,
41 Jean Delvare <khali@linux-fr.org>,
42 Greg Kroah-Hartman <greg@kroah.com>,
43 IBM Corp.
44
45Description
46-----------
47
48This is a simple EEPROM module meant to enable reading the first 256 bytes
49of an EEPROM (on a SDRAM DIMM for example). However, it will access serial
50EEPROMs on any I2C adapter. The supported devices are generically called
5124Cxx, and are listed above; however the numbering for these
52industry-standard devices may vary by manufacturer.
53
54This module was a programming exercise to get used to the new project
55organization laid out by Frodo, but it should be at least completely
56effective for decoding the contents of EEPROMs on DIMMs.
57
58DIMMS will typically contain a 24C01A or 24C02, or the 34C02 variants.
59The other devices will not be found on a DIMM because they respond to more
60than one address.
61
62DDC Monitors may contain any device. Often a 24C01, which responds to all 8
63addresses, is found.
64
65Recent Sony Vaio laptops have an EEPROM at 0x57. We couldn't get the
66specification, so it is guess work and far from being complete.
67
68The Microchip 24AA52/24LCS52, ST M34C02, and others support an additional
69software write protect register at 0x30 - 0x37 (0x20 less than the memory
70location). The chip responds to "write quick" detection at this address but
71does not respond to byte reads. If this register is present, the lower 128
72bytes of the memory array are not write protected. Any byte data write to
73this address will write protect the memory array permanently, and the
74device will no longer respond at the 0x30-37 address. The eeprom driver
75does not support this register.
76
77Lacking functionality:
78
79* Full support for larger devices (24C04, 24C08, 24C16). These are not
80typically found on a PC. These devices will appear as separate devices at
81multiple addresses.
82
83* Support for really large devices (24C32, 24C64, 24C128, 24C256, 24C512).
84These devices require two-byte address fields and are not supported.
85
86* Enable Writing. Again, no technical reason why not, but making it easy
87to change the contents of the EEPROMs (on DIMMs anyway) also makes it easy
88to disable the DIMMs (potentially preventing the computer from booting)
89until the values are restored somehow.
90
91Use:
92
93After inserting the module (and any other required SMBus/i2c modules), you
94should have some EEPROM directories in /sys/bus/i2c/devices/* of names such
95as "0-0050". Inside each of these is a series of files, the eeprom file
96contains the binary data from EEPROM.
diff --git a/Documentation/i2c/chips/max6875 b/Documentation/i2c/chips/max6875
deleted file mode 100644
index 10ca43cd1a7..00000000000
--- a/Documentation/i2c/chips/max6875
+++ /dev/null
@@ -1,108 +0,0 @@
1Kernel driver max6875
2=====================
3
4Supported chips:
5 * Maxim MAX6874, MAX6875
6 Prefix: 'max6875'
7 Addresses scanned: None (see below)
8 Datasheet:
9 http://pdfserv.maxim-ic.com/en/ds/MAX6874-MAX6875.pdf
10
11Author: Ben Gardner <bgardner@wabtec.com>
12
13
14Description
15-----------
16
17The Maxim MAX6875 is an EEPROM-programmable power-supply sequencer/supervisor.
18It provides timed outputs that can be used as a watchdog, if properly wired.
19It also provides 512 bytes of user EEPROM.
20
21At reset, the MAX6875 reads the configuration EEPROM into its configuration
22registers. The chip then begins to operate according to the values in the
23registers.
24
25The Maxim MAX6874 is a similar, mostly compatible device, with more intputs
26and outputs:
27 vin gpi vout
28MAX6874 6 4 8
29MAX6875 4 3 5
30
31See the datasheet for more information.
32
33
34Sysfs entries
35-------------
36
37eeprom - 512 bytes of user-defined EEPROM space.
38
39
40General Remarks
41---------------
42
43Valid addresses for the MAX6875 are 0x50 and 0x52.
44Valid addresses for the MAX6874 are 0x50, 0x52, 0x54 and 0x56.
45The driver does not probe any address, so you must force the address.
46
47Example:
48$ modprobe max6875 force=0,0x50
49
50The MAX6874/MAX6875 ignores address bit 0, so this driver attaches to multiple
51addresses. For example, for address 0x50, it also reserves 0x51.
52The even-address instance is called 'max6875', the odd one is 'dummy'.
53
54
55Programming the chip using i2c-dev
56----------------------------------
57
58Use the i2c-dev interface to access and program the chips.
59Reads and writes are performed differently depending on the address range.
60
61The configuration registers are at addresses 0x00 - 0x45.
62Use i2c_smbus_write_byte_data() to write a register and
63i2c_smbus_read_byte_data() to read a register.
64The command is the register number.
65
66Examples:
67To write a 1 to register 0x45:
68 i2c_smbus_write_byte_data(fd, 0x45, 1);
69
70To read register 0x45:
71 value = i2c_smbus_read_byte_data(fd, 0x45);
72
73
74The configuration EEPROM is at addresses 0x8000 - 0x8045.
75The user EEPROM is at addresses 0x8100 - 0x82ff.
76
77Use i2c_smbus_write_word_data() to write a byte to EEPROM.
78
79The command is the upper byte of the address: 0x80, 0x81, or 0x82.
80The data word is the lower part of the address or'd with data << 8.
81 cmd = address >> 8;
82 val = (address & 0xff) | (data << 8);
83
84Example:
85To write 0x5a to address 0x8003:
86 i2c_smbus_write_word_data(fd, 0x80, 0x5a03);
87
88
89Reading data from the EEPROM is a little more complicated.
90Use i2c_smbus_write_byte_data() to set the read address and then
91i2c_smbus_read_byte() or i2c_smbus_read_i2c_block_data() to read the data.
92
93Example:
94To read data starting at offset 0x8100, first set the address:
95 i2c_smbus_write_byte_data(fd, 0x81, 0x00);
96
97And then read the data
98 value = i2c_smbus_read_byte(fd);
99
100 or
101
102 count = i2c_smbus_read_i2c_block_data(fd, 0x84, 16, buffer);
103
104The block read should read 16 bytes.
1050x84 is the block read command.
106
107See the datasheet for more details.
108