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authorJean Delvare <khali@linux-fr.org>2008-07-16 19:30:06 +0200
committerJean Delvare <khali@mahadeva.delvare>2008-07-16 19:30:06 +0200
commit833bedb813689807385ae73175389c73a3f855c1 (patch)
treef9b33add52ca947fd9f8ae89753eb8d534efc70e /Documentation
parent8b77e6ac4911a79993e583ece719736a9e035b1d (diff)
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i2c: Convert the pcf8574 driver to a new-style i2c driver
The new-style pcf8574 driver implements the optional detect() callback to cover the use cases of the legacy driver. Warning: users will now have to use the force module parameter to get the driver to attach to their device. That's not a bad thing as these devices can't be detected anyway. Note that this doesn't change the fact that this driver is deprecated in favor of gpio/pcf857x. Signed-off-by: Jean Delvare <khali@linux-fr.org>
Diffstat (limited to 'Documentation')
-rw-r--r--Documentation/i2c/chips/pcf857412
1 files changed, 5 insertions, 7 deletions
diff --git a/Documentation/i2c/chips/pcf8574 b/Documentation/i2c/chips/pcf8574
index 5c1ad1376b62..235815c075ff 100644
--- a/Documentation/i2c/chips/pcf8574
+++ b/Documentation/i2c/chips/pcf8574
@@ -4,13 +4,13 @@ Kernel driver pcf8574
Supported chips:
* Philips PCF8574
Prefix: 'pcf8574'
- Addresses scanned: I2C 0x20 - 0x27
+ 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: I2C 0x38 - 0x3f
+ Addresses scanned: none
Datasheet: Publicly available at the Philips Semiconductors website
http://www.semiconductors.philips.com/pip/PCF8574P.html
@@ -38,12 +38,10 @@ For more informations see the datasheet.
Accessing PCF8574(A) via /sys interface
-------------------------------------
-! Be careful !
The PCF8574(A) is plainly impossible to detect ! Stupid chip.
-So every chip with address in the interval [20..27] and [38..3f] are
-detected as PCF8574(A). If you have other chips in this address
-range, the workaround is to load this module after the one
-for your others chips.
+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):