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author | Wolfram Sang <w.sang@pengutronix.de> | 2009-09-18 20:45:49 (GMT) |
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committer | Jean Delvare <khali@linux-fr.org> | 2009-09-18 20:45:49 (GMT) |
commit | e7c5c49ecdac6dc5a6b67a27838b1b562eeec1b9 (patch) | |
tree | 81846ad16464324ec58dabcbab0e91ba5e946381 /Documentation | |
parent | 732d481127abaa0add41ee918191ea08e9ede17e (diff) | |
download | linux-fsl-qoriq-e7c5c49ecdac6dc5a6b67a27838b1b562eeec1b9.tar.xz |
i2c/chips: Remove deprecated pcf8574 driver
The pcf8574 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sysfs is superseded by drivers/gpio/pcf857x.c which properly uses the gpiolib.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: Aurelien Jarno <aurelien@aurel32.net>
Signed-off-by: Jean Delvare <khali@linux-fr.org>
Diffstat (limited to 'Documentation')
-rw-r--r-- | Documentation/i2c/chips/pcf8574 | 65 |
1 files changed, 0 insertions, 65 deletions
diff --git a/Documentation/i2c/chips/pcf8574 b/Documentation/i2c/chips/pcf8574 deleted file mode 100644 index 235815c..0000000 --- a/Documentation/i2c/chips/pcf8574 +++ /dev/null @@ -1,65 +0,0 @@ -Kernel driver pcf8574 -===================== - -Supported chips: - * Philips PCF8574 - Prefix: 'pcf8574' - Addresses scanned: none - Datasheet: Publicly available at the Philips Semiconductors website - http://www.semiconductors.philips.com/pip/PCF8574P.html - - * Philips PCF8574A - Prefix: 'pcf8574a' - Addresses scanned: none - Datasheet: Publicly available at the Philips Semiconductors website - http://www.semiconductors.philips.com/pip/PCF8574P.html - -Authors: - Frodo Looijaard <frodol@dds.nl>, - Philip Edelbrock <phil@netroedge.com>, - Dan Eaton <dan.eaton@rocketlogix.com>, - Aurelien Jarno <aurelien@aurel32.net>, - Jean Delvare <khali@linux-fr.org>, - - -Description ------------ -The PCF8574(A) is an 8-bit I/O expander for the I2C bus produced by Philips -Semiconductors. It is designed to provide a byte I2C interface to up to 16 -separate devices (8 x PCF8574 and 8 x PCF8574A). - -This device consists of a quasi-bidirectional port. Each of the eight I/Os -can be independently used as an input or output. To setup an I/O as an -input, you have to write a 1 to the corresponding output. - -For more informations see the datasheet. - - -Accessing PCF8574(A) via /sys interface -------------------------------------- - -The PCF8574(A) is plainly impossible to detect ! Stupid chip. -So, you have to pass the I2C bus and address of the installed PCF857A -and PCF8574A devices explicitly to the driver at load time via the -force=... parameter. - -On detection (i.e. insmod, modprobe et al.), directories are being -created for each detected PCF8574(A): - -/sys/bus/i2c/devices/<0>-<1>/ -where <0> is the bus the chip was detected on (e. g. i2c-0) -and <1> the chip address ([20..27] or [38..3f]): - -(example: /sys/bus/i2c/devices/1-0020/) - -Inside these directories, there are two files each: -read and write (and one file with chip name). - -The read file is read-only. Reading gives you the current I/O input -if the corresponding output is set as 1, otherwise the current output -value, that is to say 0. - -The write file is read/write. Writing a value outputs it on the I/O -port. Reading returns the last written value. As it is not possible -to read this value from the chip, you need to write at least once to -this file before you can read back from it. |