diff options
author | Wolfram Sang <w.sang@pengutronix.de> | 2009-09-18 20:45:48 (GMT) |
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committer | Jean Delvare <khali@linux-fr.org> | 2009-09-18 20:45:48 (GMT) |
commit | 8f67eeb0b44cde19216955975ffef8513a87c0c0 (patch) | |
tree | c848851a7494b72038f24beca93362755567e8cc /Documentation | |
parent | 4ba2ccb83e03077bb94f8848ee573f1e27cea969 (diff) | |
download | linux-fsl-qoriq-8f67eeb0b44cde19216955975ffef8513a87c0c0.tar.xz |
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sysfs is superseded by drivers/gpio/pcf857x.c which properly uses the gpiolib.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')
-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 40b268e..0000000 --- a/Documentation/i2c/chips/pcf8575 +++ /dev/null @@ -1,69 +0,0 @@ -About the PCF8575 chip and the pcf8575 kernel driver -==================================================== - -The PCF8575 chip is produced by the following manufacturers: - - * Philips NXP - http://www.nxp.com/#/pip/cb=[type=product,path=50807/41735/41850,final=PCF8575_3]|pip=[pip=PCF8575_3][0] - - * Texas Instruments - http://focus.ti.com/docs/prod/folders/print/pcf8575.html - - -Some vendors sell small PCB's with the PCF8575 mounted on it. You can connect -such a board to a Linux host via e.g. an USB to I2C interface. Examples of -PCB boards with a PCF8575: - - * SFE Breakout Board for PCF8575 I2C Expander by RobotShop - http://www.robotshop.ca/home/products/robot-parts/electronics/adapters-converters/sfe-pcf8575-i2c-expander-board.html - - * Breakout Board for PCF8575 I2C Expander by Spark Fun Electronics - http://www.sparkfun.com/commerce/product_info.php?products_id=8130 - - -Description ------------ -The PCF8575 chip is a 16-bit I/O expander for the I2C bus. Up to eight of -these chips can be connected to the same I2C bus. You can find this -chip on some custom designed hardware, but you won't find it on PC -motherboards. - -The PCF8575 chip consists of a 16-bit quasi-bidirectional port and an I2C-bus -interface. Each of the sixteen I/O's can be independently used as an input or -an output. To set up an I/O pin as an input, you have to write a 1 to the -corresponding output. - -For more information please see the datasheet. - - -Detection ---------- - -There is no method known to detect whether a chip on a given I2C address is -a PCF8575 or whether it is any other I2C device, so you have to pass the I2C -bus and address of the installed PCF8575 devices explicitly to the driver at -load time via the force=... parameter. - -/sys interface --------------- - -For each address on which a PCF8575 chip was found or forced the following -files will be created under /sys: -* /sys/bus/i2c/devices/<bus>-<address>/read -* /sys/bus/i2c/devices/<bus>-<address>/write -where bus is the I2C bus number (0, 1, ...) and address is the four-digit -hexadecimal representation of the 7-bit I2C address of the PCF8575 -(0020 .. 0027). - -The read file is read-only. Reading it will trigger an I2C read and will hence -report the current input state for the pins configured as inputs, and the -current output value for the pins configured as outputs. - -The write file is read-write. Writing a value to it will configure all pins -as output for which the corresponding bit is zero. Reading the write file will -return the value last written, or -EAGAIN if no value has yet been written to -the write file. - -On module initialization the configuration of the chip is not changed -- the -chip is left in the state it was already configured in through either power-up -or through previous I2C write actions. |