From 15fae37d9f5f21571a9618d8353164b6ddfea6f6 Mon Sep 17 00:00:00 2001 From: David Brownell Date: Mon, 4 Feb 2008 22:28:24 -0800 Subject: 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 Acked-by: Jean Delvare Cc: Eric Miao Cc: Sam Ravnborg Cc: Haavard Skinnemoen Cc: Philipp Zabel Cc: Russell King Cc: Ben Gardner Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- drivers/gpio/Kconfig | 23 +++++++++++++++++++++++ 1 file changed, 23 insertions(+) (limited to 'drivers/gpio/Kconfig') diff --git a/drivers/gpio/Kconfig b/drivers/gpio/Kconfig index 560687c4667..36d5d6aefc0 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 -- cgit v1.2.3