2 # GPIO infrastructure and expanders
8 Platforms select gpiolib if they use this infrastructure
9 for all their GPIOs, usually starting with ones integrated
13 depends on HAVE_GPIO_LIB
16 bool "Debug GPIO calls"
17 depends on DEBUG_KERNEL
19 Say Y here to add some extra checks and diagnostics to GPIO calls.
20 The checks help ensure that GPIOs have been properly initialized
21 before they are used and that sleeping calls aren not made from
22 nonsleeping contexts. They can make bitbanged serial protocols
23 slower. The diagnostics help catch the type of setup errors
24 that are most common when setting up new platforms or boards.
27 bool "/sys/class/gpio/... (sysfs interface)"
28 depends on SYSFS && EXPERIMENTAL
30 Say Y here to add a sysfs interface for GPIOs.
32 This is mostly useful to work around omissions in a system's
33 kernel support. Those are common in custom and semicustom
34 hardware assembled using standard kernels with a minimum of
35 custom patches. In those cases, userspace code may import
36 a given GPIO from the kernel, if no kernel driver requested it.
38 Kernel drivers may also request that a particular GPIO be
39 exported to userspace; this can be useful when debugging.
41 # put expanders in the right section, in alphabetical order
43 comment "I2C GPIO expanders:"
46 tristate "PCA953x, PCA955x, and MAX7310 I/O ports"
49 Say yes here to provide access to several register-oriented
50 SMBus I/O expanders, made mostly by NXP or TI. Compatible
53 4 bits: pca9536, pca9537
55 8 bits: max7310, pca9534, pca9538, pca9554, pca9557
57 16 bits: pca9535, pca9539, pca9555
59 This driver can also be built as a module. If so, the module
60 will be called pca953x.
63 tristate "PCF857x, PCA{85,96}7x, and MAX732[89] I2C GPIO expanders"
66 Say yes here to provide access to most "quasi-bidirectional" I2C
67 GPIO expanders used for additional digital outputs or inputs.
68 Most of these parts are from NXP, though TI is a second source for
69 some of them. Compatible models include:
71 8 bits: pcf8574, pcf8574a, pca8574, pca8574a,
72 pca9670, pca9672, pca9674, pca9674a,
75 16 bits: pcf8575, pcf8575c, pca8575,
76 pca9671, pca9673, pca9675
78 Your board setup code will need to declare the expanders in
79 use, and assign numbers to the GPIOs they expose. Those GPIOs
80 can then be used from drivers and other kernel code, just like
81 other GPIOs, but only accessible from task contexts.
83 This driver provides an in-kernel interface to those GPIOs using
84 platform-neutral GPIO calls.
86 comment "SPI GPIO expanders:"
89 tristate "Maxim MAX7301 GPIO expander"
92 gpio driver for Maxim MAX7301 SPI GPIO expander.
95 tristate "Microchip MCP23S08 I/O expander"
98 SPI driver for Microchip MCP23S08 I/O expander. This provides
99 a GPIO interface supporting inputs and outputs.