Commit 7444a72e authored by Michael Buesch's avatar Michael Buesch Committed by Linus Torvalds
Browse files

gpiolib: allow user-selection 



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: default avatarMichael 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: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent ff1d5c2f

Documentation/gpio.txt

+11 −1
Original line number Diff line number Diff line
@@ -389,11 +389,21 @@ either NULL or the label associated with that GPIO when it was requested. 


Platform Support

----------------

To support this framework, a platform's Kconfig will "select HAVE_GPIO_LIB"

To support this framework, a platform's Kconfig will "select" either

ARCH_REQUIRE_GPIOLIB or ARCH_WANT_OPTIONAL_GPIOLIB

and arrange that its <asm/gpio.h> includes <asm-generic/gpio.h> and defines

three functions: gpio_get_value(), gpio_set_value(), and gpio_cansleep().

They may also want to provide a custom value for ARCH_NR_GPIOS.



ARCH_REQUIRE_GPIOLIB means that the gpio-lib code will always get compiled

into the kernel on that architecture.



ARCH_WANT_OPTIONAL_GPIOLIB means the gpio-lib code defaults to off and the user

can enable it and build it into the kernel optionally.



If neither of these options are selected, the platform does not support

GPIOs through GPIO-lib and the code cannot be enabled by the user.



Trivial implementations of those functions can directly use framework

code, which always dispatches through the gpio_chip:

arch/arm/Kconfig

+4 −4
Original line number Diff line number Diff line
@@ -268,7 +268,7 @@ config ARCH_EP93XX 
	select GENERIC_GPIO

	select HAVE_CLK

	select HAVE_CLK

	select HAVE_GPIO_LIB

	select ARCH_REQUIRE_GPIOLIB

	help

	  This enables support for the Cirrus EP93xx series of CPUs.
@@ -447,7 +447,7 @@ config ARCH_PXA 
	select ARCH_MTD_XIP

	select GENERIC_GPIO

	select HAVE_CLK

	select HAVE_GPIO_LIB

	select ARCH_REQUIRE_GPIOLIB

	select GENERIC_TIME

	select GENERIC_CLOCKEVENTS

	select TICK_ONESHOT
@@ -479,7 +479,7 @@ config ARCH_SA1100 
	select GENERIC_CLOCKEVENTS

	select HAVE_CLK

	select TICK_ONESHOT

	select HAVE_GPIO_LIB

	select ARCH_REQUIRE_GPIOLIB

	help

	  Support for StrongARM 11x0 based boards.
@@ -522,7 +522,7 @@ config ARCH_OMAP 
	bool "TI OMAP"

	select GENERIC_GPIO

	select HAVE_CLK

	select HAVE_GPIO_LIB

	select ARCH_REQUIRE_GPIOLIB

	select GENERIC_TIME

	select GENERIC_CLOCKEVENTS

	help

arch/avr32/Kconfig

+1 −1
Original line number Diff line number Diff line
@@ -88,7 +88,7 @@ config PLATFORM_AT32AP 
	select SUBARCH_AVR32B

	select MMU

	select PERFORMANCE_COUNTERS

	select HAVE_GPIO_LIB

	select ARCH_REQUIRE_GPIOLIB

	select GENERIC_ALLOCATOR



#

arch/mips/Kconfig

+1 −1
Original line number Diff line number Diff line
@@ -713,7 +713,7 @@ config CSRC_SB1250 


config GPIO_TXX9

	select GENERIC_GPIO

	select HAVE_GPIO_LIB

	select ARCH_REQUIRE_GPIOLIB

	bool



config CFE

arch/powerpc/Kconfig

+1 −0
Original line number Diff line number Diff line
@@ -110,6 +110,7 @@ config PPC 
	default y

	select HAVE_DYNAMIC_FTRACE

	select HAVE_FTRACE

	select ARCH_WANT_OPTIONAL_GPIOLIB

	select HAVE_IDE

	select HAVE_IOREMAP_PROT

	select HAVE_EFFICIENT_UNALIGNED_ACCESS

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