Merge branch 'devel' of master.kernel.org:/home/rmk/linux-2.6-arm

	- ARM Interrupt subsystem documentation

IXP2000

	- Release Notes for Linux on Intel's IXP2000 Network Processor

msm

	- MSM specific documentation

Netwinder

	- Netwinder specific documentation

Porting

This document provides an overview of the msm_gpiomux interface, which

is used to provide gpio pin multiplexing and configuration on mach-msm

targets.

History

=======

The first-generation API for gpio configuration & multiplexing on msm

is the function gpio_tlmm_config().  This function has a few notable

shortcomings, which led to its deprecation and replacement by gpiomux:

The 'disable' parameter:  Setting the second parameter to

gpio_tlmm_config to GPIO_CFG_DISABLE tells the peripheral

processor in charge of the subsystem to perform a look-up into a

low-power table and apply the low-power/sleep setting for the pin.

As the msm family evolved this became problematic. Not all pins

have sleep settings, not all peripheral processors will accept requests

to apply said sleep settings, and not all msm targets have their gpio

subsystems managed by a peripheral processor. In order to get consistent

behavior on all targets, drivers are forced to ignore this parameter,

rendering it useless.

The 'direction' flag: for all mux-settings other than raw-gpio (0),

the output-enable bit of a gpio is hard-wired to a known

input (usually VDD or ground).  For those settings, the direction flag

is meaningless at best, and deceptive at worst.  In addition, using the

direction flag to change output-enable (OE) directly can cause trouble in

gpiolib, which has no visibility into gpio direction changes made

in this way.  Direction control in gpio mode should be made through gpiolib.

Key Features of gpiomux

=======================

- A consistent interface across all generations of msm.  Drivers can expect

the same results on every target.

- gpiomux plays nicely with gpiolib.  Functions that should belong to gpiolib

are left to gpiolib and not duplicated here.  gpiomux is written with the

intent that gpio_chips will call gpiomux reference-counting methods

from their request() and free() hooks, providing full integration.

- Tabular configuration.  Instead of having to call gpio_tlmm_config

hundreds of times, gpio configuration is placed in a single table.

- Per-gpio sleep.  Each gpio is individually reference counted, allowing only

those lines which are in use to be put in high-power states.

- 0 means 'do nothing': all flags are designed so that the default memset-zero

equates to a sensible default of 'no configuration', preventing users

from having to provide hundreds of 'no-op' configs for unused or

unwanted lines.

Usage

=====

To use gpiomux, provide configuration information for relevant gpio lines

in the msm_gpiomux_configs table.  Since a 0 equates to "unconfigured",

only those lines to be managed by gpiomux need to be specified.  Here

is a completely fictional example:

struct msm_gpiomux_config msm_gpiomux_configs[GPIOMUX_NGPIOS] = {

	[12] = {

		.active = GPIOMUX_VALID | GPIOMUX_DRV_8MA | GPIOMUX_FUNC_1,

		.suspended = GPIOMUX_VALID | GPIOMUX_PULL_DOWN,

	},

	[34] = {

		.suspended = GPIOMUX_VALID | GPIOMUX_PULL_DOWN,

	},

};

To indicate that a gpio is in use, call msm_gpiomux_get() to increase

its reference count.  To decrease the reference count, call msm_gpiomux_put().

The effect of this configuration is as follows:

When the system boots, gpios 12 and 34 will be initialized with their

'suspended' configurations.  All other gpios, which were left unconfigured,

will not be touched.

When msm_gpiomux_get() is called on gpio 12 to raise its reference count

above 0, its active configuration will be applied.  Since no other gpio

line has a valid active configuration, msm_gpiomux_get() will have no

effect on any other line.

When msm_gpiomux_put() is called on gpio 12 or 34 to drop their reference

count to 0, their suspended configurations will be applied.

Since no other gpio line has a valid suspended configuration, no other

gpio line will be effected by msm_gpiomux_put().  Since gpio 34 has no valid

active configuration, this is effectively a no-op for gpio 34 as well,

with one small caveat, see the section "About Output-Enable Settings".

All of the GPIOMUX_VALID flags may seem like unnecessary overhead, but

they address some important issues.  As unused entries (all those

except 12 and 34) are zero-filled, gpiomux needs a way to distinguish

the used fields from the unused.  In addition, the all-zero pattern

is a valid configuration!  Therefore, gpiomux defines an additional bit

which is used to indicate when a field is used.  This has the pleasant

side-effect of allowing calls to msm_gpiomux_write to use '0' to indicate

that a value should not be changed:

  msm_gpiomux_write(0, GPIOMUX_VALID, 0);

replaces the active configuration of gpio 0 with an all-zero configuration,

but leaves the suspended configuration as it was.

Static Configurations

=====================

To install a static configuration, which is applied at boot and does

not change after that, install a configuration with a suspended component

but no active component, as in the previous example:

	[34] = {

		.suspended = GPIOMUX_VALID | GPIOMUX_PULL_DOWN,

	},

The suspended setting is applied during boot, and the lack of any valid

active setting prevents any other setting from being applied at runtime.

If other subsystems attempting to access the line is a concern, one could

*really* anchor the configuration down by calling msm_gpiomux_get on the

line at initialization to move the line into active mode.  With the line

held, it will never be re-suspended, and with no valid active configuration,

no new configurations will be applied.

But then, if having other subsystems grabbing for the line is truly a concern,

it should be reserved with gpio_request instead, which carries an implicit

msm_gpiomux_get.

gpiomux and gpiolib

===================

It is expected that msm gpio_chips will call msm_gpiomux_get() and

msm_gpiomux_put() from their request and free hooks, like this fictional

example:

static int request(struct gpio_chip *chip, unsigned offset)

{

        return msm_gpiomux_get(chip->base + offset);

}

static void free(struct gpio_chip *chip, unsigned offset)

{

        msm_gpiomux_put(chip->base + offset);

}

	...somewhere in a gpio_chip declaration...

	.request = request,

	.free    = free,

This provides important functionality:

- It guarantees that a gpio line will have its 'active' config applied

  when the line is requested, and will not be suspended while the line

  remains requested; and

- It guarantees that gpio-direction settings from gpiolib behave sensibly.

  See "About Output-Enable Settings."

This mechanism allows for "auto-request" of gpiomux lines via gpiolib

when it is suitable.  Drivers wishing more exact control are, of course,

free to also use msm_gpiomux_set and msm_gpiomux_get.

About Output-Enable Settings

============================

Some msm targets do not have the ability to query the current gpio

configuration setting.  This means that changes made to the output-enable

(OE) bit by gpiolib cannot be consistently detected and preserved by gpiomux.

Therefore, when gpiomux applies a configuration setting, any direction

settings which may have been applied by gpiolib are lost and the default

input settings are re-applied.

For this reason, drivers should not assume that gpio direction settings

continue to hold if they free and then re-request a gpio.  This seems like

common sense - after all, anybody could have obtained the line in the

meantime - but it needs saying.

This also means that calls to msm_gpiomux_write will reset the OE bit,

which means that if the gpio line is held by a client of gpiolib and

msm_gpiomux_write is called, the direction setting has been lost and

gpiolib's internal state has been broken.

Release gpio lines before reconfiguring them.

F:	arch/arm/mach-shmobile/

F:	drivers/sh/

ARM/TELECHIPS ARM ARCHITECTURE

M:	"Hans J. Koch" <hjk@linutronix.de>

L:	linux-arm-kernel@lists.infradead.org (moderated for non-subscribers)

S:	Maintained

F:	arch/arm/plat-tcc/

F:	arch/arm/mach-tcc8k/

ARM/TECHNOLOGIC SYSTEMS TS7250 MACHINE SUPPORT

M:	Lennert Buytenhek <kernel@wantstofly.org>

L:	linux-arm-kernel@lists.infradead.org (moderated for non-subscribers)

S:	Maintained

ARM/TETON BGA MACHINE SUPPORT

M:	Mark F. Brown <mark.brown314@gmail.com>

L:	linux-arm-kernel@lists.infradead.org (moderated for non-subscribers)

S:	Maintained

ARM/THECUS N2100 MACHINE SUPPORT

M:	Lennert Buytenhek <kernel@wantstofly.org>

L:	linux-arm-kernel@lists.infradead.org (moderated for non-subscribers)

ifdef CONFIG_FRAME_POINTER

KBUILD_CFLAGS	+= -fno-omit-frame-pointer -fno-optimize-sibling-calls

else

# Some targets (ARM with Thumb2, for example), can't be built with frame

# pointers.  For those, we don't have FUNCTION_TRACER automatically

# select FRAME_POINTER.  However, FUNCTION_TRACER adds -pg, and this is

# incompatible with -fomit-frame-pointer with current GCC, so we don't use

# -fomit-frame-pointer with FUNCTION_TRACER.

ifndef CONFIG_FUNCTION_TRACER

KBUILD_CFLAGS	+= -fomit-frame-pointer

endif

endif

ifdef CONFIG_DEBUG_INFO

KBUILD_CFLAGS	+= -g

	select HAVE_KPROBES if (!XIP_KERNEL)

	select HAVE_KRETPROBES if (HAVE_KPROBES)

	select HAVE_FUNCTION_TRACER if (!XIP_KERNEL)

	select HAVE_FTRACE_MCOUNT_RECORD if (!XIP_KERNEL)

	select HAVE_DYNAMIC_FTRACE if (!XIP_KERNEL)

	select HAVE_GENERIC_DMA_COHERENT

	select HAVE_KERNEL_GZIP

	select HAVE_KERNEL_LZO

	select HAVE_PERF_EVENTS

	select PERF_USE_VMALLOC

	select HAVE_REGS_AND_STACK_ACCESS_API

	select HAVE_HW_BREAKPOINT if (PERF_EVENTS && (CPU_V6 || CPU_V7))

	help

	  The ARM series is a line of low-power-consumption RISC chip designs

	  licensed by ARM Ltd and targeted at embedded applications and

	  and that the relevant menu configurations are displayed for

	  it.

config ARCH_HAS_CPU_IDLE_WAIT

       def_bool y

config GENERIC_HWEIGHT

	bool

	default y

	select GENERIC_CLOCKEVENTS

	select TICK_ONESHOT

	select PLAT_PXA

	select SPARSE_IRQ

	help

	  Support for Marvell's PXA168/PXA910(MMP) and MMP2 processor line.

	select GENERIC_CLOCKEVENTS

	select TICK_ONESHOT

	select PLAT_PXA

	select SPARSE_IRQ

	help

	  Support for Intel/Marvell's PXA2xx/PXA3xx processor line.

	help

	  Samsung S3C64XX series based systems

config ARCH_S5P6440

	bool "Samsung S5P6440"

config ARCH_S5P64X0

	bool "Samsung S5P6440 S5P6450"

	select CPU_V6

	select GENERIC_GPIO

	select HAVE_CLK

	select HAVE_S3C2410_I2C

	select HAVE_S3C_RTC

	help

	  Samsung S5P6440 CPU based systems

	  Samsung S5P64X0 CPU based systems, such as the Samsung SMDK6440,

	  SMDK6450.

config ARCH_S5P6442

	bool "Samsung S5P6442"

	  Support for the StrongARM based Digital DNARD machine, also known

	  as "Shark" (<http://www.shark-linux.de/shark.html>).

config ARCH_TCC_926

	bool "Telechips TCC ARM926-based systems"

	select CPU_ARM926T

	select HAVE_CLK

	select COMMON_CLKDEV

	select GENERIC_CLOCKEVENTS

	help

	  Support for Telechips TCC ARM926-based systems.

config ARCH_LH7A40X

	bool "Sharp LH7A40X"

	select CPU_ARM922T

source "arch/arm/plat-spear/Kconfig"

source "arch/arm/plat-tcc/Kconfig"

if ARCH_S3C2410

source "arch/arm/mach-s3c2400/Kconfig"

source "arch/arm/mach-s3c2410/Kconfig"

source "arch/arm/mach-s3c64xx/Kconfig"

endif

source "arch/arm/mach-s5p6440/Kconfig"

source "arch/arm/mach-s5p64x0/Kconfig"

source "arch/arm/mach-s5p6442/Kconfig"

config ARM_ERRATA_411920

	bool "ARM errata: Invalidation of the Instruction Cache operation can fail"

	depends on CPU_V6 && !SMP

	depends on CPU_V6

	help

	  Invalidation of the Instruction Cache operation can

	  fail. This erratum is present in 1136 (before r1p4), 1156 and 1176.

config SMP

	bool "Symmetric Multi-Processing (EXPERIMENTAL)"

	depends on EXPERIMENTAL && (REALVIEW_EB_ARM11MP || REALVIEW_EB_A9MP ||\

		 MACH_REALVIEW_PB11MP || MACH_REALVIEW_PBX || ARCH_OMAP4 ||\

		 ARCH_S5PV310 || ARCH_TEGRA || ARCH_U8500 || ARCH_VEXPRESS_CA9X4)

	depends on EXPERIMENTAL

	depends on GENERIC_CLOCKEVENTS

	depends on REALVIEW_EB_ARM11MP || REALVIEW_EB_A9MP || \

		 MACH_REALVIEW_PB11MP || MACH_REALVIEW_PBX || ARCH_OMAP4 ||\

		 ARCH_S5PV310 || ARCH_TEGRA || ARCH_U8500 || ARCH_VEXPRESS_CA9X4

	select USE_GENERIC_SMP_HELPERS

	select HAVE_ARM_SCU if ARCH_REALVIEW || ARCH_OMAP4 || ARCH_S5PV310 ||\

		 ARCH_TEGRA || ARCH_U8500 || ARCH_VEXPRESS_CA9X4

	select HAVE_ARM_SCU

	help

	  This enables support for systems with more than one CPU. If you have

	  a system with only one CPU, like most personal computers, say N. If

	  If you don't know what to do here, say N.

config SMP_ON_UP

	bool "Allow booting SMP kernel on uniprocessor systems (EXPERIMENTAL)"

	depends on EXPERIMENTAL

	depends on SMP && !XIP && !THUMB2_KERNEL

	default y

	help

	  SMP kernels contain instructions which fail on non-SMP processors.

	  Enabling this option allows the kernel to modify itself to make

	  these instructions safe.  Disabling it allows about 1K of space

	  savings.

	  If you don't know what to do here, say Y.

config HAVE_ARM_SCU

	bool

	depends on SMP

config LOCAL_TIMERS

	bool "Use local timer interrupts"

	depends on SMP && (REALVIEW_EB_ARM11MP || MACH_REALVIEW_PB11MP || \

		REALVIEW_EB_A9MP || MACH_REALVIEW_PBX || ARCH_OMAP4 || \

		ARCH_S5PV310 || ARCH_TEGRA || ARCH_U8500 || ARCH_VEXPRESS_CA9X4)

	depends on SMP

	default y

	select HAVE_ARM_TWD if ARCH_REALVIEW || ARCH_OMAP4 || ARCH_S5PV310 || \

		ARCH_TEGRA || ARCH_U8500 || ARCH_VEXPRESS

	select HAVE_ARM_TWD

	help

	  Enable support for local timers on SMP platforms, rather then the

	  legacy IPI broadcast method.  Local timers allows the system

config HZ

	int

	default 200 if ARCH_EBSA110 || ARCH_S3C2410 || ARCH_S5P6440 || \

	default 200 if ARCH_EBSA110 || ARCH_S3C2410 || ARCH_S5P64X0 || \

		ARCH_S5P6442 || ARCH_S5PV210 || ARCH_S5PV310

	default OMAP_32K_TIMER_HZ if ARCH_OMAP && OMAP_32K_TIMER

	default AT91_TIMER_HZ if ARCH_AT91

	  However, if the CPU data cache is using a write-allocate mode,

	  this option is unlikely to provide any performance gain.

config SECCOMP

	bool

	prompt "Enable seccomp to safely compute untrusted bytecode"

	---help---

	  This kernel feature is useful for number crunching applications

	  that may need to compute untrusted bytecode during their

	  execution. By using pipes or other transports made available to

	  the process as file descriptors supporting the read/write

	  syscalls, it's possible to isolate those applications in

	  their own address space using seccomp. Once seccomp is

	  enabled via prctl(PR_SET_SECCOMP), it cannot be disabled

	  and the task is only allowed to execute a few safe syscalls

	  defined by each seccomp mode.

config CC_STACKPROTECTOR

	bool "Enable -fstack-protector buffer overflow detection (EXPERIMENTAL)"

	help