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authorDavid Brownell <dbrownell@users.sourceforge.net>2008-02-04 22:28:24 -0800
committerLinus Torvalds <torvalds@woody.linux-foundation.org>2008-02-05 09:44:13 -0800
commit15fae37d9f5f21571a9618d8353164b6ddfea6f6 (patch)
tree13b4fb5479cf3a9522c6673cc6ccae20b6658e55 /drivers/gpio/Kconfig
parent1c44f5f16fee880b294f8068354bfb9dddf1349b (diff)
downloadop-kernel-dev-15fae37d9f5f21571a9618d8353164b6ddfea6f6.zip
op-kernel-dev-15fae37d9f5f21571a9618d8353164b6ddfea6f6.tar.gz
gpiolib: pcf857x i2c gpio expander support
This is a new-style I2C driver for most common 8 and 16 bit I2C based "quasi-bidirectional" GPIO expanders: pcf8574 or pcf8575, and several compatible models (mostly faster, supporting I2C at up to 1 MHz). The driver exposes the GPIO signals using the platform-neutral GPIO programming interface, so they are easily accessed by other kernel code. The lack of such a flexible kernel API has been a big factor in the proliferation of board-specific drivers for these chips... stuff that rarely makes it upstream since it's so ugly. This driver will let such boards use standard calls. Since it's a new-style driver, these devices must be configured as part of board-specific init. That eliminates the need for error-prone manual configuration of module parameters, and makes compatibility with legacy drivers (pcf8574.c, pc8575.c) for these chips easier (there's a clear either/or disjunction). Signed-off-by: David Brownell <dbrownell@users.sourceforge.net> Acked-by: Jean Delvare <khali@linux-fr.org> Cc: Eric Miao <eric.miao@marvell.com> Cc: Sam Ravnborg <sam@ravnborg.org> Cc: Haavard Skinnemoen <hskinnemoen@atmel.com> Cc: Philipp Zabel <philipp.zabel@gmail.com> Cc: Russell King <rmk@arm.linux.org.uk> Cc: Ben Gardner <bgardner@wabtec.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'drivers/gpio/Kconfig')
-rw-r--r--drivers/gpio/Kconfig23
1 files changed, 23 insertions, 0 deletions
diff --git a/drivers/gpio/Kconfig b/drivers/gpio/Kconfig
index 560687c..36d5d6a 100644
--- a/drivers/gpio/Kconfig
+++ b/drivers/gpio/Kconfig
@@ -27,6 +27,29 @@ config DEBUG_GPIO
comment "I2C GPIO expanders:"
+config GPIO_PCF857X
+ tristate "PCF857x, PCA857x, and PCA967x I2C GPIO expanders"
+ depends on I2C
+ help
+ Say yes here to provide access to most "quasi-bidirectional" I2C
+ GPIO expanders used for additional digital outputs or inputs.
+ Most of these parts are from NXP, though TI is a second source for
+ some of them. Compatible models include:
+
+ 8 bits: pcf8574, pcf8574a, pca8574, pca8574a,
+ pca9670, pca9672, pca9674, pca9674a
+
+ 16 bits: pcf8575, pcf8575c, pca8575,
+ pca9671, pca9673, pca9675
+
+ Your board setup code will need to declare the expanders in
+ use, and assign numbers to the GPIOs they expose. Those GPIOs
+ can then be used from drivers and other kernel code, just like
+ other GPIOs, but only accessible from task contexts.
+
+ This driver provides an in-kernel interface to those GPIOs using
+ platform-neutral GPIO calls.
+
comment "SPI GPIO expanders:"
endmenu
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