i2c: Add support for the PCF8575 chip

Signed-off-by: Bart Van Assche <bart.vanassche@gmail.com>
Signed-off-by: Jean Delvare <khali@linux-fr.org>
diff --git a/drivers/i2c/chips/Kconfig b/drivers/i2c/chips/Kconfig
index 2e1c24f..17702b3 100644
--- a/drivers/i2c/chips/Kconfig
+++ b/drivers/i2c/chips/Kconfig
@@ -57,7 +57,7 @@
 	default n
 	help
 	  If you say yes here you get support for Philips PCF8574 and 
-	  PCF8574A chips.
+	  PCF8574A chips. These chips are 8-bit I/O expanders for the I2C bus.
 
 	  This driver can also be built as a module.  If so, the module
 	  will be called pcf8574.
@@ -65,6 +65,20 @@
 	  These devices are hard to detect and rarely found on mainstream
 	  hardware.  If unsure, say N.
 
+config PCF8575
+	tristate "Philips PCF8575"
+	default n
+	help
+	  If you say yes here you get support for Philips PCF8575 chip.
+	  This chip is a 16-bit I/O expander for the I2C bus.  Several other
+	  chip manufacturers sell equivalent chips, e.g. Texas Instruments.
+
+	  This driver can also be built as a module.  If so, the module
+	  will be called pcf8575.
+
+	  This device is hard to detect and is rarely found on mainstream
+	  hardware.  If unsure, say N.
+
 config SENSORS_PCA9539
 	tristate "Philips PCA9539 16-bit I/O port"
 	depends on EXPERIMENTAL