7444a72eff
This patch adds functionality to the gpio-lib subsystem to make it possible to enable the gpio-lib code even if the architecture code didn't request to get it built in. The archtitecture code does still need to implement the gpiolib accessor functions in its asm/gpio.h file. This patch adds the implementations for x86 and PPC. With these changes it is possible to run generic GPIO expansion cards on every architecture that implements the trivial wrapper functions. Support for more architectures can easily be added. Signed-off-by: Michael Buesch <mb@bu3sch.de> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Stephen Rothwell <sfr@canb.auug.org.au> Cc: David Brownell <david-b@pacbell.net> Cc: Russell King <rmk@arm.linux.org.uk> Cc: Haavard Skinnemoen <hskinnemoen@atmel.com> Cc: Jesper Nilsson <jesper.nilsson@axis.com> Cc: Ralf Baechle <ralf@linux-mips.org> Cc: Paul Mackerras <paulus@samba.org> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Ingo Molnar <mingo@elte.hu> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Jean Delvare <khali@linux-fr.org> Cc: Samuel Ortiz <sameo@openedhand.com> Cc: Kumar Gala <galak@gate.crashing.org> Cc: Sam Ravnborg <sam@ravnborg.org> Cc: Adrian Bunk <bunk@stusta.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
144 lines
4.4 KiB
Text
144 lines
4.4 KiB
Text
#
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# GPIO infrastructure and expanders
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#
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config ARCH_WANT_OPTIONAL_GPIOLIB
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bool
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help
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Select this config option from the architecture Kconfig, if
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it is possible to use gpiolib on the architecture, but let the
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user decide whether to actually build it or not.
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Select this instead of ARCH_REQUIRE_GPIOLIB, if your architecture does
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not depend on GPIOs being available, but rather let the user
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decide whether he needs it or not.
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config ARCH_REQUIRE_GPIOLIB
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bool
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select GPIOLIB
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help
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Platforms select gpiolib if they use this infrastructure
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for all their GPIOs, usually starting with ones integrated
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into SOC processors.
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Selecting this from the architecture code will cause the gpiolib
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code to always get built in.
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menuconfig GPIOLIB
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bool "GPIO Support"
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depends on ARCH_WANT_OPTIONAL_GPIOLIB || ARCH_REQUIRE_GPIOLIB
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select GENERIC_GPIO
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help
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This enables GPIO support through the generic GPIO library.
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You only need to enable this, if you also want to enable
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one or more of the GPIO expansion card drivers below.
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If unsure, say N.
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if GPIOLIB
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config DEBUG_GPIO
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bool "Debug GPIO calls"
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depends on DEBUG_KERNEL
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help
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Say Y here to add some extra checks and diagnostics to GPIO calls.
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The checks help ensure that GPIOs have been properly initialized
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before they are used and that sleeping calls aren not made from
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nonsleeping contexts. They can make bitbanged serial protocols
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slower. The diagnostics help catch the type of setup errors
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that are most common when setting up new platforms or boards.
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config GPIO_SYSFS
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bool "/sys/class/gpio/... (sysfs interface)"
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depends on SYSFS && EXPERIMENTAL
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help
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Say Y here to add a sysfs interface for GPIOs.
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This is mostly useful to work around omissions in a system's
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kernel support. Those are common in custom and semicustom
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hardware assembled using standard kernels with a minimum of
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custom patches. In those cases, userspace code may import
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a given GPIO from the kernel, if no kernel driver requested it.
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Kernel drivers may also request that a particular GPIO be
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exported to userspace; this can be useful when debugging.
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# put expanders in the right section, in alphabetical order
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comment "I2C GPIO expanders:"
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config GPIO_PCA953X
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tristate "PCA953x, PCA955x, and MAX7310 I/O ports"
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depends on I2C
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help
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Say yes here to provide access to several register-oriented
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SMBus I/O expanders, made mostly by NXP or TI. Compatible
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models include:
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4 bits: pca9536, pca9537
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8 bits: max7310, pca9534, pca9538, pca9554, pca9557
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16 bits: pca9535, pca9539, pca9555
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This driver can also be built as a module. If so, the module
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will be called pca953x.
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config GPIO_PCF857X
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tristate "PCF857x, PCA{85,96}7x, and MAX732[89] I2C GPIO expanders"
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depends on I2C
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help
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Say yes here to provide access to most "quasi-bidirectional" I2C
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GPIO expanders used for additional digital outputs or inputs.
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Most of these parts are from NXP, though TI is a second source for
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some of them. Compatible models include:
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8 bits: pcf8574, pcf8574a, pca8574, pca8574a,
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pca9670, pca9672, pca9674, pca9674a,
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max7328, max7329
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16 bits: pcf8575, pcf8575c, pca8575,
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pca9671, pca9673, pca9675
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Your board setup code will need to declare the expanders in
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use, and assign numbers to the GPIOs they expose. Those GPIOs
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can then be used from drivers and other kernel code, just like
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other GPIOs, but only accessible from task contexts.
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This driver provides an in-kernel interface to those GPIOs using
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platform-neutral GPIO calls.
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comment "PCI GPIO expanders:"
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config GPIO_BT8XX
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tristate "BT8XX GPIO abuser"
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depends on PCI && VIDEO_BT848=n
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help
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The BT8xx frame grabber chip has 24 GPIO pins than can be abused
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as a cheap PCI GPIO card.
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This chip can be found on Miro, Hauppauge and STB TV-cards.
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The card needs to be physically altered for using it as a
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GPIO card. For more information on how to build a GPIO card
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from a BT8xx TV card, see the documentation file at
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Documentation/bt8xxgpio.txt
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If unsure, say N.
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comment "SPI GPIO expanders:"
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config GPIO_MAX7301
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tristate "Maxim MAX7301 GPIO expander"
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depends on SPI_MASTER
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help
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gpio driver for Maxim MAX7301 SPI GPIO expander.
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config GPIO_MCP23S08
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tristate "Microchip MCP23S08 I/O expander"
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depends on SPI_MASTER
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help
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SPI driver for Microchip MCP23S08 I/O expander. This provides
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a GPIO interface supporting inputs and outputs.
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endif
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