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# GPIO infrastructure and expanders
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config HAVE_GPIO_LIB
bool
help
Platforms select gpiolib if they use this infrastructure
for all their GPIOs, usually starting with ones integrated
into SOC processors.
menu "GPIO Support"
depends on HAVE_GPIO_LIB
config DEBUG_GPIO
bool "Debug GPIO calls"
depends on DEBUG_KERNEL
help
Say Y here to add some extra checks and diagnostics to GPIO calls.
The checks help ensure that GPIOs have been properly initialized
before they are used and that sleeping calls aren not made from
nonsleeping contexts. They can make bitbanged serial protocols
slower. The diagnostics help catch the type of setup errors
that are most common when setting up new platforms or boards.
config GPIO_SYSFS
bool "/sys/class/gpio/... (sysfs interface)"
depends on SYSFS && EXPERIMENTAL
help
Say Y here to add a sysfs interface for GPIOs.
This is mostly useful to work around omissions in a system's
kernel support. Those are common in custom and semicustom
hardware assembled using standard kernels with a minimum of
custom patches. In those cases, userspace code may import
a given GPIO from the kernel, if no kernel driver requested it.
Kernel drivers may also request that a particular GPIO be
exported to userspace; this can be useful when debugging.
# put expanders in the right section, in alphabetical order
comment "I2C GPIO expanders:"
config GPIO_PCA953X
tristate "PCA953x, PCA955x, and MAX7310 I/O ports"
depends on I2C
help
Say yes here to provide access to several register-oriented
SMBus I/O expanders, made mostly by NXP or TI. Compatible
models include:
4 bits: pca9536, pca9537
8 bits: max7310, pca9534, pca9538, pca9554, pca9557
16 bits: pca9535, pca9539, pca9555
This driver can also be built as a module. If so, the module
will be called pca953x.
config GPIO_PCF857X
tristate "PCF857x, PCA{85,96}7x, and MAX732[89] 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,
max7328, max7329
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:"
config GPIO_MAX7301
tristate "Maxim MAX7301 GPIO expander"
depends on SPI_MASTER
help
gpio driver for Maxim MAX7301 SPI GPIO expander.
config GPIO_MCP23S08
tristate "Microchip MCP23S08 I/O expander"
depends on SPI_MASTER
help
SPI driver for Microchip MCP23S08 I/O expander. This provides
a GPIO interface supporting inputs and outputs.
endmenu
