1a9c5fff5SDavid Brownell# 2a9c5fff5SDavid Brownell# GPIO infrastructure and expanders 3a9c5fff5SDavid Brownell# 4a9c5fff5SDavid Brownell 5a9c5fff5SDavid Brownellconfig HAVE_GPIO_LIB 6a9c5fff5SDavid Brownell bool 7a9c5fff5SDavid Brownell help 8a9c5fff5SDavid Brownell Platforms select gpiolib if they use this infrastructure 9a9c5fff5SDavid Brownell for all their GPIOs, usually starting with ones integrated 10a9c5fff5SDavid Brownell into SOC processors. 11a9c5fff5SDavid Brownell 12a9c5fff5SDavid Brownellmenu "GPIO Support" 13a9c5fff5SDavid Brownell depends on HAVE_GPIO_LIB 14a9c5fff5SDavid Brownell 15a9c5fff5SDavid Brownellconfig DEBUG_GPIO 16a9c5fff5SDavid Brownell bool "Debug GPIO calls" 17a9c5fff5SDavid Brownell depends on DEBUG_KERNEL 18a9c5fff5SDavid Brownell help 19a9c5fff5SDavid Brownell Say Y here to add some extra checks and diagnostics to GPIO calls. 20a9c5fff5SDavid Brownell The checks help ensure that GPIOs have been properly initialized 21a9c5fff5SDavid Brownell before they are used and that sleeping calls aren not made from 22a9c5fff5SDavid Brownell nonsleeping contexts. They can make bitbanged serial protocols 23a9c5fff5SDavid Brownell slower. The diagnostics help catch the type of setup errors 24a9c5fff5SDavid Brownell that are most common when setting up new platforms or boards. 25a9c5fff5SDavid Brownell 26*d8f388d8SDavid Brownellconfig GPIO_SYSFS 27*d8f388d8SDavid Brownell bool "/sys/class/gpio/... (sysfs interface)" 28*d8f388d8SDavid Brownell depends on SYSFS && EXPERIMENTAL 29*d8f388d8SDavid Brownell help 30*d8f388d8SDavid Brownell Say Y here to add a sysfs interface for GPIOs. 31*d8f388d8SDavid Brownell 32*d8f388d8SDavid Brownell This is mostly useful to work around omissions in a system's 33*d8f388d8SDavid Brownell kernel support. Those are common in custom and semicustom 34*d8f388d8SDavid Brownell hardware assembled using standard kernels with a minimum of 35*d8f388d8SDavid Brownell custom patches. In those cases, userspace code may import 36*d8f388d8SDavid Brownell a given GPIO from the kernel, if no kernel driver requested it. 37*d8f388d8SDavid Brownell 38*d8f388d8SDavid Brownell Kernel drivers may also request that a particular GPIO be 39*d8f388d8SDavid Brownell exported to userspace; this can be useful when debugging. 40*d8f388d8SDavid Brownell 41a9c5fff5SDavid Brownell# put expanders in the right section, in alphabetical order 42a9c5fff5SDavid Brownell 43a9c5fff5SDavid Brownellcomment "I2C GPIO expanders:" 44a9c5fff5SDavid Brownell 45f3dc3630SGuennadi Liakhovetskiconfig GPIO_PCA953X 467059d4b0SDavid Brownell tristate "PCA953x, PCA955x, and MAX7310 I/O ports" 479e60fdcfSeric miao depends on I2C 489e60fdcfSeric miao help 497059d4b0SDavid Brownell Say yes here to provide access to several register-oriented 507059d4b0SDavid Brownell SMBus I/O expanders, made mostly by NXP or TI. Compatible 517059d4b0SDavid Brownell models include: 527059d4b0SDavid Brownell 537059d4b0SDavid Brownell 4 bits: pca9536, pca9537 547059d4b0SDavid Brownell 557059d4b0SDavid Brownell 8 bits: max7310, pca9534, pca9538, pca9554, pca9557 567059d4b0SDavid Brownell 577059d4b0SDavid Brownell 16 bits: pca9535, pca9539, pca9555 589e60fdcfSeric miao 599e60fdcfSeric miao This driver can also be built as a module. If so, the module 60f3dc3630SGuennadi Liakhovetski will be called pca953x. 619e60fdcfSeric miao 6215fae37dSDavid Brownellconfig GPIO_PCF857X 631673ad52SDavid Brownell tristate "PCF857x, PCA{85,96}7x, and MAX732[89] I2C GPIO expanders" 6415fae37dSDavid Brownell depends on I2C 6515fae37dSDavid Brownell help 6615fae37dSDavid Brownell Say yes here to provide access to most "quasi-bidirectional" I2C 6715fae37dSDavid Brownell GPIO expanders used for additional digital outputs or inputs. 6815fae37dSDavid Brownell Most of these parts are from NXP, though TI is a second source for 6915fae37dSDavid Brownell some of them. Compatible models include: 7015fae37dSDavid Brownell 7115fae37dSDavid Brownell 8 bits: pcf8574, pcf8574a, pca8574, pca8574a, 721673ad52SDavid Brownell pca9670, pca9672, pca9674, pca9674a, 731673ad52SDavid Brownell max7328, max7329 7415fae37dSDavid Brownell 7515fae37dSDavid Brownell 16 bits: pcf8575, pcf8575c, pca8575, 7615fae37dSDavid Brownell pca9671, pca9673, pca9675 7715fae37dSDavid Brownell 7815fae37dSDavid Brownell Your board setup code will need to declare the expanders in 7915fae37dSDavid Brownell use, and assign numbers to the GPIOs they expose. Those GPIOs 8015fae37dSDavid Brownell can then be used from drivers and other kernel code, just like 8115fae37dSDavid Brownell other GPIOs, but only accessible from task contexts. 8215fae37dSDavid Brownell 8315fae37dSDavid Brownell This driver provides an in-kernel interface to those GPIOs using 8415fae37dSDavid Brownell platform-neutral GPIO calls. 8515fae37dSDavid Brownell 86a9c5fff5SDavid Brownellcomment "SPI GPIO expanders:" 87a9c5fff5SDavid Brownell 880c36ec31SJuergen Beisertconfig GPIO_MAX7301 890c36ec31SJuergen Beisert tristate "Maxim MAX7301 GPIO expander" 900c36ec31SJuergen Beisert depends on SPI_MASTER 910c36ec31SJuergen Beisert help 920c36ec31SJuergen Beisert gpio driver for Maxim MAX7301 SPI GPIO expander. 930c36ec31SJuergen Beisert 94e58b9e27SDavid Brownellconfig GPIO_MCP23S08 95e58b9e27SDavid Brownell tristate "Microchip MCP23S08 I/O expander" 96e58b9e27SDavid Brownell depends on SPI_MASTER 97e58b9e27SDavid Brownell help 98e58b9e27SDavid Brownell SPI driver for Microchip MCP23S08 I/O expander. This provides 99e58b9e27SDavid Brownell a GPIO interface supporting inputs and outputs. 100e58b9e27SDavid Brownell 101a9c5fff5SDavid Brownellendmenu 102