diff options
author | Wolfram Sang <w.sang@pengutronix.de> | 2009-09-18 16:45:48 -0400 |
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committer | Jean Delvare <khali@linux-fr.org> | 2009-09-18 16:45:48 -0400 |
commit | 8f67eeb0b44cde19216955975ffef8513a87c0c0 (patch) | |
tree | c848851a7494b72038f24beca93362755567e8cc /Documentation/i2c | |
parent | 4ba2ccb83e03077bb94f8848ee573f1e27cea969 (diff) |
i2c/chips: Remove deprecated pcf8575 driver
The pcf8575 driver in drivers/i2c/chips which just exports its register to
sysfs is superseded by drivers/gpio/pcf857x.c which properly uses the gpiolib.
As this driver has been deprecated for more than a year, finally remove it.
Signed-off-by: Wolfram Sang <w.sang@pengutronix.de>
Cc: Bart Van Assche <bart.vanassche@gmail.com>
Signed-off-by: Jean Delvare <khali@linux-fr.org>
Diffstat (limited to 'Documentation/i2c')
-rw-r--r-- | Documentation/i2c/chips/pcf8575 | 69 |
1 files changed, 0 insertions, 69 deletions
diff --git a/Documentation/i2c/chips/pcf8575 b/Documentation/i2c/chips/pcf8575 deleted file mode 100644 index 40b268eb276f..000000000000 --- a/Documentation/i2c/chips/pcf8575 +++ /dev/null | |||
@@ -1,69 +0,0 @@ | |||
1 | About the PCF8575 chip and the pcf8575 kernel driver | ||
2 | ==================================================== | ||
3 | |||
4 | The PCF8575 chip is produced by the following manufacturers: | ||
5 | |||
6 | * Philips NXP | ||
7 | http://www.nxp.com/#/pip/cb=[type=product,path=50807/41735/41850,final=PCF8575_3]|pip=[pip=PCF8575_3][0] | ||
8 | |||
9 | * Texas Instruments | ||
10 | http://focus.ti.com/docs/prod/folders/print/pcf8575.html | ||
11 | |||
12 | |||
13 | Some vendors sell small PCB's with the PCF8575 mounted on it. You can connect | ||
14 | such a board to a Linux host via e.g. an USB to I2C interface. Examples of | ||
15 | PCB boards with a PCF8575: | ||
16 | |||
17 | * SFE Breakout Board for PCF8575 I2C Expander by RobotShop | ||
18 | http://www.robotshop.ca/home/products/robot-parts/electronics/adapters-converters/sfe-pcf8575-i2c-expander-board.html | ||
19 | |||
20 | * Breakout Board for PCF8575 I2C Expander by Spark Fun Electronics | ||
21 | http://www.sparkfun.com/commerce/product_info.php?products_id=8130 | ||
22 | |||
23 | |||
24 | Description | ||
25 | ----------- | ||
26 | The PCF8575 chip is a 16-bit I/O expander for the I2C bus. Up to eight of | ||
27 | these chips can be connected to the same I2C bus. You can find this | ||
28 | chip on some custom designed hardware, but you won't find it on PC | ||
29 | motherboards. | ||
30 | |||
31 | The PCF8575 chip consists of a 16-bit quasi-bidirectional port and an I2C-bus | ||
32 | interface. Each of the sixteen I/O's can be independently used as an input or | ||
33 | an output. To set up an I/O pin as an input, you have to write a 1 to the | ||
34 | corresponding output. | ||
35 | |||
36 | For more information please see the datasheet. | ||
37 | |||
38 | |||
39 | Detection | ||
40 | --------- | ||
41 | |||
42 | There is no method known to detect whether a chip on a given I2C address is | ||
43 | a PCF8575 or whether it is any other I2C device, so you have to pass the I2C | ||
44 | bus and address of the installed PCF8575 devices explicitly to the driver at | ||
45 | load time via the force=... parameter. | ||
46 | |||
47 | /sys interface | ||
48 | -------------- | ||
49 | |||
50 | For each address on which a PCF8575 chip was found or forced the following | ||
51 | files will be created under /sys: | ||
52 | * /sys/bus/i2c/devices/<bus>-<address>/read | ||
53 | * /sys/bus/i2c/devices/<bus>-<address>/write | ||
54 | where bus is the I2C bus number (0, 1, ...) and address is the four-digit | ||
55 | hexadecimal representation of the 7-bit I2C address of the PCF8575 | ||
56 | (0020 .. 0027). | ||
57 | |||
58 | The read file is read-only. Reading it will trigger an I2C read and will hence | ||
59 | report the current input state for the pins configured as inputs, and the | ||
60 | current output value for the pins configured as outputs. | ||
61 | |||
62 | The write file is read-write. Writing a value to it will configure all pins | ||
63 | as output for which the corresponding bit is zero. Reading the write file will | ||
64 | return the value last written, or -EAGAIN if no value has yet been written to | ||
65 | the write file. | ||
66 | |||
67 | On module initialization the configuration of the chip is not changed -- the | ||
68 | chip is left in the state it was already configured in through either power-up | ||
69 | or through previous I2C write actions. | ||