linux-toradex.git/drivers/gpio/gpiolib.c, branch v2.6.28.10

gpiolib: fix request related issue

2009-02-02T17:53:26+00:00

commit 7460db567bbca76bf087d1694d792a1a96bdaa26 upstream.

Fix request-already-requested handling in gpio_request().

Signed-off-by: Magnus Damm 
Acked-by: David Brownell 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds 
Signed-off-by: Greg Kroah-Hartman

gpiolib: extend gpio label column width in debugfs file

2008-11-20T02:49:57+00:00

There are already various drivers having bigger label than 12 bytes.  Most
of them fit well under 20 bytes but make column width exact so that
oversized labels don't mess up output alignment.

Signed-off-by: Jarkko Nikula 
Acked-by: David Brownell 
Cc: 		[2.6.26.x, 2.6.26.x, 2.6.27.x]
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

Merge branch 'genirq-v28-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip

2008-10-20T20:23:01+00:00

This merges branches irq/genirq, irq/sparseirq-v4, timers/hpet-percpu
and x86/uv.

The sparseirq branch is just preliminary groundwork: no sparse IRQs are
actually implemented by this tree anymore - just the new APIs are added
while keeping the old way intact as well (the new APIs map 1:1 to
irq_desc[]).  The 'real' sparse IRQ support will then be a relatively
small patch ontop of this - with a v2.6.29 merge target.

* 'genirq-v28-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip: (178 commits)
  genirq: improve include files
  intr_remapping: fix typo
  io_apic: make irq_mis_count available on 64-bit too
  genirq: fix name space collisions of nr_irqs in arch/*
  genirq: fix name space collision of nr_irqs in autoprobe.c
  genirq: use iterators for irq_desc loops
  proc: fixup irq iterator
  genirq: add reverse iterator for irq_desc
  x86: move ack_bad_irq() to irq.c
  x86: unify show_interrupts() and proc helpers
  x86: cleanup show_interrupts
  genirq: cleanup the sparseirq modifications
  genirq: remove artifacts from sparseirq removal
  genirq: revert dynarray
  genirq: remove irq_to_desc_alloc
  genirq: remove sparse irq code
  genirq: use inline function for irq_to_desc
  genirq: consolidate nr_irqs and for_each_irq_desc()
  x86: remove sparse irq from Kconfig
  genirq: define nr_irqs for architectures with GENERIC_HARDIRQS=n
  ...

gpiolib: fix oops in gpio_get_value_cansleep()

2008-10-20T15:52:36+00:00

We can get the following oops from gpio_get_value_cansleep() when a GPIO
controller doesn't provide a get() callback:

 Unable to handle kernel paging request for instruction fetch
 Faulting instruction address: 0x00000000
 Oops: Kernel access of bad area, sig: 11 [#1]
 [...]
 NIP [00000000] 0x0
 LR [c0182fb0] gpio_get_value_cansleep+0x40/0x50
 Call Trace:
 [c7b79e80] [c0183f28] gpio_value_show+0x5c/0x94
 [c7b79ea0] [c01a584c] dev_attr_show+0x30/0x7c
 [c7b79eb0] [c00d6b48] fill_read_buffer+0x68/0xe0
 [c7b79ed0] [c00d6c54] sysfs_read_file+0x94/0xbc
 [c7b79ef0] [c008f24c] vfs_read+0xb4/0x16c
 [c7b79f10] [c008f580] sys_read+0x4c/0x90
 [c7b79f40] [c0013a14] ret_from_syscall+0x0/0x38

It's OK to request the value of *any* GPIO; most GPIOs are bidirectional,
so configuring them as outputs just enables an output driver and doesn't
disable the input logic.

So the problem is that gpio_get_value_cansleep() isn't making the same
sanity check that gpio_get_value() does: making sure this GPIO isn't one
of the atypical "no input logic" cases.

Reported-by: Anton Vorontsov 
Signed-off-by: David Brownell 
Cc: 		[2.6.27.x, 2.6.26.x, 2.6.25.x]
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

gpio: modify sysfs gpio export so that "value" displays as 0 or 1

2008-10-20T15:52:36+00:00

gpiolib can export GPIOs to userspace via sysfs.  This patch modifies the
gpio_value_show() so that any non-zero value is explicitly printed as "1",
rather than whatever numerical value the lower-level driver returns.

Signed-off-by: Steve Falco 
Signed-off-by: David Brownell 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

gpiolib: request/free hooks

2008-10-16T18:21:40+00:00

Add a new internal mechanism to gpiolib to support low power
operations by letting gpio_chip instances see when their GPIOs
are in use.  When no GPIOs are active, chips may be able to
enter lower powered runtime states by disabling clocks and/or
power domains.

Signed-off-by: David Brownell 
Cc: "Magnus Damm" 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

gpiolib: gpio_to_irq() hooks

2008-10-16T18:21:40+00:00

Add a new gpiolib mechanism: gpio_chip instances can provide mappings
between their (input) GPIOs and any associated IRQs.  This makes it easier
for platforms to support IRQs that are provided by board-specific external
chips instead of as part of their core (such as SOC-integrated GPIOs).

Also update the irq_to_gpio() description, saying to avoid it because it's
not always supported.

Signed-off-by: David Brownell 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

gpio_free might sleep, generic part

2008-10-16T18:21:40+00:00

According to the documentation gpio_free should only be called from task
context only.  To make this more explicit add a might sleep to all
implementations.

This is the generic part which changes gpiolib and the fallback
implementation only.

Signed-off-by: Uwe Kleine-König 
Cc: David Brownell 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

generic: sparse irqs: use irq_desc() together with dyn_array, instead of irq_desc[]

2008-10-16T14:52:29+00:00

add CONFIG_HAVE_SPARSE_IRQ to for use condensed array.
Get rid of irq_desc[] array assumptions.

Preallocate 32 irq_desc, and irq_desc() will try to get more.

( No change in functionality is expected anywhere, except the odd build
  failure where we missed a code site or where a crossing commit itroduces
  new irq_desc[] usage. )

v2: according to Eric, change get_irq_desc() to irq_desc()

Signed-off-by: Yinghai Lu 
Signed-off-by: Ingo Molnar

gpio: sysfs interface

2008-07-25T17:53:30+00:00

This adds a simple sysfs interface for GPIOs.

    /sys/class/gpio
    	/export ... asks the kernel to export a GPIO to userspace
    	/unexport ... to return a GPIO to the kernel
        /gpioN ... for each exported GPIO #N
	    /value ... always readable, writes fail for input GPIOs
	    /direction ... r/w as: in, out (default low); write high, low
	/gpiochipN ... for each gpiochip; #N is its first GPIO
	    /base ... (r/o) same as N
	    /label ... (r/o) descriptive, not necessarily unique
	    /ngpio ... (r/o) number of GPIOs; numbered N .. N+(ngpio - 1)

GPIOs claimed by kernel code may be exported by its owner using a new
gpio_export() call, which should be most useful for driver debugging.
Such exports may optionally be done without a "direction" attribute.

Userspace may ask to take over a GPIO by writing to a sysfs control file,
helping to cope with incomplete board support or other "one-off"
requirements that don't merit full kernel support:

  echo 23 > /sys/class/gpio/export
	... will gpio_request(23, "sysfs") and gpio_export(23);
	use /sys/class/gpio/gpio-23/direction to (re)configure it,
	when that GPIO can be used as both input and output.
  echo 23 > /sys/class/gpio/unexport
	... will gpio_free(23), when it was exported as above

The extra D-space footprint is a few hundred bytes, except for the sysfs
resources associated with each exported GPIO.  The additional I-space
footprint is about two thirds of the current size of gpiolib (!).  Since
no /dev node creation is involved, no "udev" support is needed.

Related changes:

  * This adds a device pointer to "struct gpio_chip".  When GPIO
    providers initialize that, sysfs gpio class devices become children of
    that device instead of being "virtual" devices.

  * The (few) gpio_chip providers which have such a device node have
    been updated.

  * Some gpio_chip drivers also needed to update their module "owner"
    field ...  for which missing kerneldoc was added.

  * Some gpio_chips don't support input GPIOs.  Those GPIOs are now
    flagged appropriately when the chip is registered.

Based on previous patches, and discussion both on and off LKML.

A Documentation/ABI/testing/sysfs-gpio update is ready to submit once this
merges to mainline.

[akpm@linux-foundation.org: a few maintenance build fixes]
Signed-off-by: David Brownell 
Cc: Guennadi Liakhovetski 
Cc: Greg KH 
Cc: Kay Sievers 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds