1
0
Fork 0
Commit Graph

78 Commits (redonkable)

Author SHA1 Message Date
Andy Shevchenko 77cb907abe gpiolib: acpi: Split ACPI stuff to gpiolib-acpi.h
This is a follow up to the commit

  f626d6dfb7 ("gpio: of: Break out OF-only code")

which broke down OF parts of GPIO library. Here we do the similar to ACPI.

Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Link: https://lore.kernel.org/r/20190730104337.21235-2-andriy.shevchenko@linux.intel.com
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
2019-07-31 00:57:21 +02:00
Linus Walleij f626d6dfb7 gpio: of: Break out OF-only code
The core gpiolib should not contain any OF/device tree-only
code. Try to break out the main part of it and push it down
into the optional gpiolib-of.c part of the library.

Create a local gpiolib-of.h header and move stuff around a
bit to get a clean cut.

Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Link: https://lore.kernel.org/r/20190717071001.3858-1-linus.walleij@linaro.org
2019-07-28 23:07:59 +02:00
Sebastian Andrzej Siewior f0b40863be gpiolib: Use spinlock_t instead of struct spinlock
For spinlocks the type spinlock_t should be used instead of "struct
spinlock".

Use spinlock_t for spinlock's definition.

Cc: linux-gpio@vger.kernel.org
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Link: https://lore.kernel.org/r/20190704153803.12739-8-bigeasy@linutronix.de
Reviewed-by: Bartosz Golaszewski <bgolaszewski@baylibre.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
2019-07-06 20:14:22 +02:00
Linus Torvalds 8148c17b17 This is the bulk of the GPIO changes for the v5.2 kernel cycle:
Core changes:
 - The gpiolib MMIO driver has been enhanced to handle two direction
   registers, i.e. one register to set lines as input and one register
   to set lines as output. It turns out some silicon engineer thinks
   the ability to configure a line as input and output at the same
   time makes sense, this can be debated but includes a lot of analog
   electronics reasoning, and the registers are there and need to
   be handled consistently. Unsurprisingly, we enforce the lines to
   be either inputs or outputs in such schemes.
 - Send in the proper argument value to .set_config() dispatched to
   the pin control subsystem. Nobody used it before, now someone
   does, so fix it to work as expected.
 - The ACPI gpiolib portions can now handle pin bias setting (pull up
   or pull down). This has been in the ACPI spec for years and we
   finally have it properly integrated with Linux GPIOs. It was based
   on an observation from Andy Schevchenko that Thomas Petazzoni's
   changes to the core for biasing the PCA950x GPIO expander actually
   happen to fit hand-in-glove with what the ACPI core needed.
   Such nice synergies happen sometimes.
 
 New drivers:
 - A new driver for the Mellanox BlueField GPIO controller. This is
   using 64bit MMIO registers and can configure lines as inputs
   and outputs at the same time and after improving the MMIO library
   we handle it just fine. Interesting.
 - A new IXP4xx proper gpiochip driver with hierarchical interrupts
   should be coming in from the ARM SoC tree as well.
 
 Driver enhancements:
 - The PCA053x driver handles the CAT9554 GPIO expander.
 - The PCA053x driver handles the NXP PCAL6416 GPIO expander.
 - Wake-up support on PCA053x GPIO lines.
 - OMAP now does a nice asynchronous IRQ handling on wake-ups by
   letting everything wake up on edges, and this makes runtime PM
   work as expected too.
 
 Misc:
 - Several cleanups such as devres fixes.
 - Get rid of some languager comstructs that cause problems when
   compiling with LLVMs clang.
 - Documentation review and update.
 -----BEGIN PGP SIGNATURE-----
 
 iQIcBAABAgAGBQJc1olZAAoJEEEQszewGV1zEU4P/RmTf3hG8xmNPS3MDTmR6gAy
 /YJOXjXBf3CD/dmEAyyaNLnUQismrtRNvHSoEGbno7gkU+htzp9UfUJkj6+HIXs2
 RpF+Hi78HzZNDxGWuBLu6OZolpmBtx+sRKOhHk/XfNS45qd1FgXWDuulzsYa9Xsr
 hYMXdtdv9wY/vcc68q1rtKAbzlu5ZNCa3Zj1iNOr/XQt3Nl2BW66hGLgjK4mOvgx
 fJy4rFXuDIMfDvo69U1Opz2b39sfE7XMhfZS/MOgg4yEV9zGRgDoI1tyMcTqGb8Q
 8LQbp5dXkP+3dJQB8tgbu3Vk4WC1Rd/pmIli5sMgsk0HYQ6XegfT6HJKozSmwN9r
 0s8jKlrocWZvdPo1aJwQgtRS56t2rFWcrcRye8bLqxkkW5cYIq9CwkE8USwB31Kv
 PFpoOwRuCtj0gkCxf7WIEcC5NAkYPow3K1KPdk3E0Si6I3pj0NqqlaAD0JAlkC2V
 aPq3xbTuFCAdmcADEt2Z+dUJ7WIs5Y9oQgosMAx+A2AD4K3QDBMu3pZsT6SCu4XZ
 mK0eWJi9/CvOj/s7bA0BEJVxQA+p8KYsNRBOULg/8aAOqGcLnSydQjqrxDTE8YrL
 xmmRG7i7ht0B9CchZuIB5hqdvjbCgvcVa5OnCUDfLxE0GdCx8iJ9y9OrsMXbabYq
 8FcPDo1N38cTYLnLqvKI
 =rhto
 -----END PGP SIGNATURE-----

Merge tag 'gpio-v5.2-1' of git://git.kernel.org/pub/scm/linux/kernel/git/linusw/linux-gpio

Pull gpio updates from Linus Walleij:
 "This is the bulk of the GPIO changes for the v5.2 kernel cycle. A bit
  later than usual because I was ironing out my own mistakes. I'm
  holding some stuff back for the next kernel as a result, and this
  should be a healthy and well tested batch.

  Core changes:

   - The gpiolib MMIO driver has been enhanced to handle two direction
     registers, i.e. one register to set lines as input and one register
     to set lines as output. It turns out some silicon engineer thinks
     the ability to configure a line as input and output at the same
     time makes sense, this can be debated but includes a lot of analog
     electronics reasoning, and the registers are there and need to be
     handled consistently. Unsurprisingly, we enforce the lines to be
     either inputs or outputs in such schemes.

   - Send in the proper argument value to .set_config() dispatched to
     the pin control subsystem. Nobody used it before, now someone does,
     so fix it to work as expected.

   - The ACPI gpiolib portions can now handle pin bias setting (pull up
     or pull down). This has been in the ACPI spec for years and we
     finally have it properly integrated with Linux GPIOs. It was based
     on an observation from Andy Schevchenko that Thomas Petazzoni's
     changes to the core for biasing the PCA950x GPIO expander actually
     happen to fit hand-in-glove with what the ACPI core needed. Such
     nice synergies happen sometimes.

  New drivers:

   - A new driver for the Mellanox BlueField GPIO controller. This is
     using 64bit MMIO registers and can configure lines as inputs and
     outputs at the same time and after improving the MMIO library we
     handle it just fine. Interesting.

   - A new IXP4xx proper gpiochip driver with hierarchical interrupts
     should be coming in from the ARM SoC tree as well.

  Driver enhancements:

   - The PCA053x driver handles the CAT9554 GPIO expander.

   - The PCA053x driver handles the NXP PCAL6416 GPIO expander.

   - Wake-up support on PCA053x GPIO lines.

   - OMAP now does a nice asynchronous IRQ handling on wake-ups by
     letting everything wake up on edges, and this makes runtime PM work
     as expected too.

  Misc:

   - Several cleanups such as devres fixes.

   - Get rid of some languager comstructs that cause problems when
     compiling with LLVMs clang.

   - Documentation review and update"

* tag 'gpio-v5.2-1' of git://git.kernel.org/pub/scm/linux/kernel/git/linusw/linux-gpio: (85 commits)
  gpio: Update documentation
  docs: gpio: convert docs to ReST and rename to *.rst
  gpio: sch: Remove write-only core_base
  gpio: pxa: Make two symbols static
  gpiolib: acpi: Respect pin bias setting
  gpiolib: acpi: Add acpi_gpio_update_gpiod_lookup_flags() helper
  gpiolib: acpi: Set pin value, based on bias, more accurately
  gpiolib: acpi: Change type of dflags
  gpiolib: Introduce GPIO_LOOKUP_FLAGS_DEFAULT
  gpiolib: Make use of enum gpio_lookup_flags consistent
  gpiolib: Indent entry values of enum gpio_lookup_flags
  gpio: pca953x: add support for pca6416
  dt-bindings: gpio: pca953x: document the nxp,pca6416
  gpio: pca953x: add pcal6416 to the of_device_id table
  gpio: gpio-omap: Remove conditional pm_runtime handling for GPIO interrupts
  gpio: gpio-omap: configure edge detection for level IRQs for idle wakeup
  tracing: stop making gpio tracing configurable
  gpio: pca953x: Configure wake-up path when wake-up is enabled
  gpio: of: Optimize quirk checks
  gpio: mmio: Drop bgpio_dir_inverted
  ...
2019-05-11 10:54:43 -04:00
Andy Shevchenko 2d3b6db122 gpiolib: acpi: Respect pin bias setting
For now, we don't take into account the pin bias settings supplied by ACPI.
This change is targeting the mentioned gap.

Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Acked-by: Hans de Goede <hdegoede@redhat.com>
Reviewed-by: Mika Westerberg <mika.westerberg@linux.intel.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
2019-04-23 10:55:28 +02:00
Andy Shevchenko 606be34440 gpiolib: acpi: Add acpi_gpio_update_gpiod_lookup_flags() helper
This helper consolidates all settings of GPIO descriptor lookup flags and
quirks in the future if any.

No functional change intended.

Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Acked-by: Hans de Goede <hdegoede@redhat.com>
Reviewed-by: Mika Westerberg <mika.westerberg@linux.intel.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
2019-04-23 10:55:24 +02:00
Andy Shevchenko fed7026adc gpiolib: Make use of enum gpio_lookup_flags consistent
The library uses enum gpio_lookup_flags to define the possible
characteristics of GPIO pin. Since enumerator listed only individual
bits the common use of it is in a form of a bitmask of
gpio_lookup_flags GPIO_* values. The more correct type for this is
unsigned long.

Due to above convert all users to use unsigned long instead of
enum gpio_lookup_flags except enumerator definition.

While here, make field and parameter descriptions consistent as well.

Suggested-by: Mika Westerberg <mika.westerberg@linux.intel.com>
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Reviewed-by: Mika Westerberg <mika.westerberg@linux.intel.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
2019-04-23 10:55:07 +02:00
Jan Kundrát 64ebde5b0f gpiolib: export devprop_gpiochip_set_names()
This function is needed in mcp23s08. That driver is a special snowflake
because it supports several hardware chips as a single "GPIO chip" under
Linux.

Signed-off-by: Jan Kundrát <jan.kundrat@cesnet.cz>
Cc: Linus Walleij <linus.walleij@linaro.org>
Cc: Phil Reid <preid@electromag.com.au>
Acked-by: Mika Westerberg <mika.westerberg@linux.intel.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
2019-03-24 04:48:02 +01:00
Thomas Petazzoni d449991c4d gpio: add core support for pull-up/pull-down configuration
This commit adds support for configuring the pull-up and pull-down
resistors available in some GPIO controllers. While configuring
pull-up/pull-down is already possible through the pinctrl subsystem,
some GPIO controllers, especially simple ones such as GPIO expanders
on I2C, don't have any pinmuxing capability and therefore do not use
the pinctrl subsystem.

This commit implements the GPIO_PULL_UP and GPIO_PULL_DOWN flags,
which can be used from the Device Tree, to enable a pull-up or
pull-down resistor on a given GPIO.

The flag is simply propagated all the way to the core GPIO subsystem,
where it is used to call the gpio_chip ->set_config callback with the
appropriate existing PIN_CONFIG_BIAS_* values.

Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
2019-02-13 09:10:14 +01:00
Linus Walleij fe6c473e3e
gpio: Export gpiod_get_from_of_node()
This function already exist inside gpiolib, we were just
reluctant to make it available to the kernel at large as
the devm_* seemed to be enough for anyone.

However we found out that regulators need to do their own
lifecycle/refcounting on GPIO descriptors and explicitly
call gpiod_put() when done with a descriptor, so export
this function so we can hand the refcounting over to the
regulator core for these descriptors after retrieveal.

Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Reviewed-by: Marek Szyprowski <m.szyprowski@samsung.com>
Tested-by: Marek Szyprowski <m.szyprowski@samsung.com>
Reviewed-by: Charles Keepax <ckeepax@opensource.cirrus.com>
Signed-off-by: Mark Brown <broonie@kernel.org>
2018-12-11 01:04:04 +00:00
Geert Uytterhoeven 3c940660cb gpio: Restore indentation of continued lines
Fixes: 3027743f83 ("gpio: Remove VLA from gpiolib")
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
2018-10-01 12:22:41 +02:00
Linus Walleij dae5f0afcf gpio: Use SPDX header for core library
Use the SPDX headers and cut down on boilerplate to indicate the
license in the core gpiolib implementation.

Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
2018-09-25 09:08:48 +02:00
Linus Walleij a2ab170374 Merge branch 'ib-array-bitmaps' into devel 2018-09-20 08:36:36 -07:00
Janusz Krzysztofik 77588c14ac gpiolib: Pass array info to get/set array functions
In order to make use of array info obtained from gpiod_get_array() and
speed up processing of arrays matching single GPIO chip layout, that
information must be passed to get/set array functions.  Extend the
functions' API with that additional parameter and update all users.
Pass NULL if a user builds an array itself from single GPIOs.

Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Miguel Ojeda Sandonis <miguel.ojeda.sandonis@gmail.com>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Sebastien Bourdelin <sebastien.bourdelin@savoirfairelinux.com>
Cc: Lukas Wunner <lukas@wunner.de>
Cc: Peter Korsgaard <peter.korsgaard@barco.com>
Cc: Peter Rosin <peda@axentia.se>
Cc: Andrew Lunn <andrew@lunn.ch>
Cc: Florian Fainelli <f.fainelli@gmail.com>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Rojhalat Ibrahim <imr@rtschenk.de>
Cc: Dominik Brodowski <linux@dominikbrodowski.net>
Cc: Russell King <rmk+kernel@armlinux.org.uk>
Cc: Kishon Vijay Abraham I <kishon@ti.com>
Cc: Tony Lindgren <tony@atomide.com>
Cc: Lars-Peter Clausen <lars@metafoo.de>
Cc: Michael Hennerich <Michael.Hennerich@analog.com>
Cc: Jonathan Cameron <jic23@kernel.org>
Cc: Hartmut Knaack <knaack.h@gmx.de>
Cc: Peter Meerwald-Stadler <pmeerw@pmeerw.net>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Jiri Slaby <jslaby@suse.com>
Cc: Yegor Yefremov <yegorslists@googlemail.com>
Cc: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Signed-off-by: Janusz Krzysztofik <jmkrzyszt@gmail.com>
Acked-by: Ulf Hansson <ulf.hansson@linaro.org>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
2018-09-13 11:16:54 +02:00
Janusz Krzysztofik bf9346f5d4 gpiolib: Identify arrays matching GPIO hardware
Certain GPIO array lookup results may map directly to GPIO pins of a
single GPIO chip in hardware order.  If that condition is recognized
and handled efficiently, significant performance gain of get/set array
functions may be possible.

While processing a request for an array of GPIO descriptors, identify
those which represent corresponding pins of a single GPIO chip.  Skip
over pins which require open source or open drain special processing.
Moreover, identify pins which require inversion.  Pass a pointer to
that information with the array to the caller so it can benefit from
enhanced performance as soon as get/set array functions can accept and
make efficient use of it.

Cc: Jonathan Corbet <corbet@lwn.net>
Signed-off-by: Janusz Krzysztofik <jmkrzyszt@gmail.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
2018-09-13 11:16:12 +02:00
Janusz Krzysztofik b9762bebc6 gpiolib: Pass bitmaps, not integer arrays, to get/set array
Most users of get/set array functions iterate consecutive bits of data,
usually a single integer, while processing array of results obtained
from, or building an array of values to be passed to those functions.
Save time wasted on those iterations by changing the functions' API to
accept bitmaps.

All current users are updated as well.

More benefits from the change are expected as soon as planned support
for accepting/passing those bitmaps directly from/to respective GPIO
chip callbacks if applicable is implemented.

Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Miguel Ojeda Sandonis <miguel.ojeda.sandonis@gmail.com>
Cc: Sebastien Bourdelin <sebastien.bourdelin@savoirfairelinux.com>
Cc: Lukas Wunner <lukas@wunner.de>
Cc: Peter Korsgaard <peter.korsgaard@barco.com>
Cc: Peter Rosin <peda@axentia.se>
Cc: Andrew Lunn <andrew@lunn.ch>
Cc: Florian Fainelli <f.fainelli@gmail.com>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Rojhalat Ibrahim <imr@rtschenk.de>
Cc: Dominik Brodowski <linux@dominikbrodowski.net>
Cc: Russell King <rmk+kernel@armlinux.org.uk>
Cc: Kishon Vijay Abraham I <kishon@ti.com>
Cc: Tony Lindgren <tony@atomide.com>
Cc: Lars-Peter Clausen <lars@metafoo.de>
Cc: Michael Hennerich <Michael.Hennerich@analog.com>
Cc: Jonathan Cameron <jic23@kernel.org>
Cc: Hartmut Knaack <knaack.h@gmx.de>
Cc: Peter Meerwald-Stadler <pmeerw@pmeerw.net>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Jiri Slaby <jslaby@suse.com>
Cc: Yegor Yefremov <yegorslists@googlemail.com>
Cc: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Signed-off-by: Janusz Krzysztofik <jmkrzyszt@gmail.com>
Acked-by: Ulf Hansson <ulf.hansson@linaro.org>
Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be>
Tested-by: Geert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
2018-09-13 11:15:30 +02:00
Hans Verkuil 4e9439ddac gpiolib: add flag to indicate if the irq is disabled
GPIO drivers call gpiochip_(un)lock_as_irq whenever they want to use a gpio
as an interrupt. This is done when the irq is requested and it marks the
gpio as in use by an interrupt.

This is problematic for cases where a gpio pin is used as an interrupt
pin, then, after the irq is disabled, is used as a regular gpio pin.
Currently it is not possible to do this other than by first freeing
the interrupt so gpiochip_unlock_as_irq is called, since an attempt to
switch the gpio direction for output will fail since gpiolib believes
that the gpio is in use for an interrupt and it does not know that it
the irq is actually disabled.

There are currently two drivers that would like to be able to do this:
the tda998x_drv.c driver where a regular gpio pin needs to be temporarily
reconfigured as an interrupt pin during CEC calibration, and the cec-gpio
driver where you want to configure the gpio pin as an interrupt while
waiting for traffic over the CEC bus, or as a regular pin when receiving or
transmitting a CEC message.

The solution is to add a new flag that is set when the irq is enabled,
and have gpiod_direction_output check for that flag.

We also add functions that drivers that do not use GPIOLIB_IRQCHIP
can call when they enable/disable the irq.

Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
2018-09-10 08:56:11 +02:00
Andy Shevchenko b23ec59926 gpiolib: Mark gpio_suffixes array with __maybe_unused
Since we put static variable to a header file it's copied to each module
that includes the header. But not all of them are actually used it.

Mark gpio_suffixes array with __maybe_unused to hide a compiler warning:

In file included from
drivers/gpio/gpiolib-legacy.c:6:0:
drivers/gpio/gpiolib.h:95:27: warning: ‘gpio_suffixes’ defined but not used [-Wunused-const-variable=]
 static const char * const gpio_suffixes[] = { "gpios", "gpio" };
                           ^~~~~~~~~~~~~
In file included from drivers/gpio/gpiolib-devprop.c:17:0:
drivers/gpio/gpiolib.h:95:27: warning: ‘gpio_suffixes’ defined but not used [-Wunused-const-variable=]
 static const char * const gpio_suffixes[] = { "gpios", "gpio" };
                           ^~~~~~~~~~~~~

Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
2018-07-13 09:00:08 +02:00
Laura Abbott 3027743f83 gpio: Remove VLA from gpiolib
The new challenge is to remove VLAs from the kernel
(see https://lkml.org/lkml/2018/3/7/621) to eventually
turn on -Wvla.

Using a kmalloc array is the easy way to fix this but kmalloc is still
more expensive than stack allocation. Introduce a fast path with a
fixed size stack array to cover most chip with gpios below some fixed
amount. The slow path dynamically allocates an array to cover those
chips with a large number of gpios.

Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be>
Reviewed-by: Phil Reid <preid@electromag.com.au>
Reviewed-and-tested-by: Lukas Wunner <lukas@wunner.de>
Signed-off-by: Lukas Wunner <lukas@wunner.de>
Signed-off-by: Laura Abbott <labbott@redhat.com>
Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
2018-05-23 14:01:03 +02:00
Linus Walleij 63f2dc0a76 gpio: include consumer header in gpiolib.h
We are forward-declaring enum gpiod_flags, but this is not referenced
by pointer, it is a real struct member, so we need to actually include
it to compile anything including the local gpiolib.h header.

Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
2018-02-22 15:30:31 +01:00
Linus Torvalds 9798f5178f The is the bulk of GPIO changes for the v4.16 kernel cycle.
Core changes:
 
 - Disallow open drain and open source flags to be set
   simultaneously. This doesn't make electrical sense, and would
   the hardware actually respond to this setting, the result
   would be short circuit.
 
 - ACPI GPIO has a new core infrastructure for handling quirks.
   The quirks are there to deal with broken ACPI tables centrally
   instead of pushing the work to individual drivers. In the world
   of BIOS writers, the ACPI tables are perfect. Until they find a
   mistake in it. When such a mistake is found, we can patch it
   with a quirk. It should never happen, the problem is that it
   happens. So we accomodate for it.
 
 - Several documentation updates.
 
 - Revert the patch setting up initial direction state from
   reading the device. This was causing bad things for drivers
   that can't read status on all its pins. It is only affecting
   debugfs information quality.
 
 - Label descriptors with the device name if no explicit label is
   passed in.
 
 - Pave the ground for transitioning SPI and regulators to use
   GPIO descriptors by implementing some quirks in the device tree
   GPIO parsing code.
 
 New drivers:
 
 - New driver for the Access PCIe IDIO 24 family.
 
 Other:
 
 - Major refactorings and improvements to the GPIO mockup driver
   used for test and verification.
 
 - Moved the AXP209 driver over to pin control since it gained a
   pin control back-end. These patches will appear (with the same
   hashes) in the pin control pull request as well.
 
 - Convert the onewire GPIO driver w1-gpio to use descriptors.
   This is merged here since the W1 maintainers send very few
   pull requests and he ACKed it.
 
 - Start to clean up driver headers using <linux/gpio.h> to just
   use <linux/gpio/driver.h> as appropriate.
 -----BEGIN PGP SIGNATURE-----
 
 iQIcBAABAgAGBQJacIW6AAoJEEEQszewGV1z9b0P/jxWKaCAGFTTu/HZQ79RBAFq
 w33nIazzoh+88sN7A9xKexpr4ibOxiCvOwkTtrUBNaxGGy5fslj4+OY5BzunEfBK
 1vYxyEqtenvvZK03pOd6CSfHKV+vD5ngnVHGdtGzRvtmDDiSgtzqyEyUhQcXM+l7
 PrEh6qrd4TBZezlVR8kn5eqcmclkCBVSQCuLSq+ThMmCKRZuOdf1Im3D6eBzh1/N
 P81HdcglqbSsfUl1RcFiHs9Z+KcZOq83CNl2Ej1LePK2JBZbmkx9dR+WSJmV1u4P
 6wvzFcQDhfGEiiteg2BS5c+o6aAyShpuRNut+2MLre8icmdfpqUEqFotHbfQjW5y
 sqaejGsJ5aHcRBq7UUM+F9s1R0iN3tlafi3L0WEhl0Tn5huRQq3Uqcw6e5l+XrWd
 0h+b5PbKJZO/iqzRhSl+rhc0V2CFDJOCwvY+JX6356fvrcF0T6LhvKfDYtKU3Iyb
 HB0RG1OcYe228f96azvafCkFyBIYX9mqHBvOXpQQgrZQYXfN1rupLvpOhxC+Wbvn
 nsGE2bdD6HA1bytTbkxbL+QWP7faHf5YVcZpaN7UWbO3sOzL46fj8eHwHUim95Tr
 pR5kDZRhZd8+9SCNZ/ttpaEbis9MOqS/3Mlxrj4GXtfFFmR53hjFy2bG/Z7R2RB0
 MlSEJRc8iDIs+1j3D2RR
 =k5nL
 -----END PGP SIGNATURE-----

Merge tag 'gpio-v4.16-1' of git://git.kernel.org/pub/scm/linux/kernel/git/linusw/linux-gpio

Pull GPIO updates from Linus Walleij:
 "The is the bulk of GPIO changes for the v4.16 kernel cycle. It is
  pretty calm this time around I think. I even got time to get to things
  like starting to clean up header includes.

  Core changes:

   - Disallow open drain and open source flags to be set simultaneously.
     This doesn't make electrical sense, and would the hardware actually
     respond to this setting, the result would be short circuit.

   - ACPI GPIO has a new core infrastructure for handling quirks. The
     quirks are there to deal with broken ACPI tables centrally instead
     of pushing the work to individual drivers. In the world of BIOS
     writers, the ACPI tables are perfect. Until they find a mistake in
     it. When such a mistake is found, we can patch it with a quirk. It
     should never happen, the problem is that it happens. So we
     accomodate for it.

   - Several documentation updates.

   - Revert the patch setting up initial direction state from reading
     the device. This was causing bad things for drivers that can't read
     status on all its pins. It is only affecting debugfs information
     quality.

   - Label descriptors with the device name if no explicit label is
     passed in.

   - Pave the ground for transitioning SPI and regulators to use GPIO
     descriptors by implementing some quirks in the device tree GPIO
     parsing code.

  New drivers:

   - New driver for the Access PCIe IDIO 24 family.

  Other:

   - Major refactorings and improvements to the GPIO mockup driver used
     for test and verification.

   - Moved the AXP209 driver over to pin control since it gained a pin
     control back-end. These patches will appear (with the same hashes)
     in the pin control pull request as well.

   - Convert the onewire GPIO driver w1-gpio to use descriptors. This is
     merged here since the W1 maintainers send very few pull requests
     and he ACKed it.

   - Start to clean up driver headers using <linux/gpio.h> to just use
     <linux/gpio/driver.h> as appropriate"

* tag 'gpio-v4.16-1' of git://git.kernel.org/pub/scm/linux/kernel/git/linusw/linux-gpio: (103 commits)
  gpio: Timestamp events in hardirq handler
  gpio: Fix kernel stack leak to userspace
  gpio: Fix a documentation spelling mistake
  gpio: Documentation update
  gpiolib: remove redundant initialization of pointer desc
  gpio: of: Fix NPE from OF flags
  gpio: stmpe: Delete an unnecessary variable initialisation in stmpe_gpio_probe()
  gpio: stmpe: Move an assignment in stmpe_gpio_probe()
  gpio: stmpe: Improve a size determination in stmpe_gpio_probe()
  gpio: stmpe: Use seq_putc() in stmpe_dbg_show()
  gpio: No NULL owner
  gpio: stmpe: i2c transfer are forbiden in atomic context
  gpio: davinci: Include proper header
  gpio: da905x: Include proper header
  gpio: cs5535: Include proper header
  gpio: crystalcove: Include proper header
  gpio: bt8xx: Include proper header
  gpio: bcm-kona: Include proper header
  gpio: arizona: Include proper header
  gpio: amd8111: Include proper header
  ...
2018-01-31 12:25:27 -08:00
Linus Walleij 92542edc42 gpio: Export devm_gpiod_get_from_of_node() for consumers
We have been holding back on adding an API for fetching GPIO handles
directly from device nodes, strongly preferring to get it from the
spawn devices instead.

The fwnode interface however already contains an API for doing this,
as it is used for opaque device tree nodes or ACPI nodes for getting
handles to LEDs and keys that use GPIO: those are specified as one
child per LED/key in the device tree and are not individual devices.

However regulators present a special problem as they already have
helper functions to traverse the device tree from a regulator node
and two levels down to fill in data, and as it already traverses
GPIO nodes in its own way, and already holds a pointer to each
regulators device tree node, it makes most sense to export an
API to fetch the GPIO descriptor directly from the node.

We only support the devm_* version for now, hopefully no non-devres
version will be needed.

Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
2018-01-12 11:05:24 +01:00
Christophe Leroy 8227033547 gpio: fix "gpio-line-names" property retrieval
Following commit 9427ecbed4 ("gpio: Rework of_gpiochip_set_names()
to use device property accessors"), "gpio-line-names" DT property is
not retrieved anymore when chip->parent is not set by the driver.
This is due to OF based property reads having been replaced by device
based property reads.

This patch fixes that by making use of
fwnode_property_read_string_array() instead of
device_property_read_string_array() and handing over either
of_fwnode_handle(chip->of_node) or dev_fwnode(chip->parent)
to that function.

Fixes: 9427ecbed4 ("gpio: Rework of_gpiochip_set_names() to use device property accessors")
Cc: stable@vger.kernel.org
Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
Acked-by: Mika Westerberg <mika.westerberg@linux.intel.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
2017-12-22 15:24:31 +01:00
Bartosz Golaszewski 3b469b0a13 gpiolib: constify label in gpio_device
This string is never modified. Make it const.

Signed-off-by: Bartosz Golaszewski <brgl@bgdev.pl>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
2017-12-20 09:01:50 +01:00
Andrew Jeffery e10f72bf4b gpio: gpiolib: Generalise state persistence beyond sleep
General support for state persistence is added to gpiolib with the
introduction of a new pinconf parameter to propagate the request to
hardware. The existing persistence support for sleep is adapted to
include hardware support if the GPIO driver provides it. Persistence
continues to be enabled by default; in-kernel consumers can opt out, but
userspace (currently) does not have a choice.

The *_SLEEP_MAY_LOSE_VALUE and *_SLEEP_MAINTAIN_VALUE symbols are
renamed, dropping the SLEEP prefix to reflect that the concept is no
longer sleep-specific.  I feel that renaming to just *_MAY_LOSE_VALUE
could initially be misinterpreted, so I've further changed the symbols
to *_TRANSITORY and *_PERSISTENT to address this.

The sysfs interface is modified only to keep consistency with the
chardev interface in enforcing persistence for userspace exports.

Signed-off-by: Andrew Jeffery <andrew@aj.id.au>
Reviewed-by: Charles Keepax <ckeepax@opensource.cirrus.com>
Acked-by: Rob Herring <robh@kernel.org>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
2017-12-02 22:42:34 +01:00
Andy Shevchenko ce0929d222 gpiolib: acpi: Add quirks field to struct acpi_gpio_mapping
Some broken ACPI tables might require quirks in the OS.
Introduce quirks field in struct acpi_gpio_mapping.

Propagate them to struct acpi_gpio_info for further use.

Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Reviewed-by: Mika Westerberg <mika.westerberg@linux.intel.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
2017-11-30 10:53:51 +01:00
Andy Shevchenko 5c34b6c146 gpiolib: acpi: Consolidate debug output in acpi_gpio_update_gpiod_flags()
We have the duplicated debug strings printed whenever
acpi_gpio_update_gpiod_flags() fails. Instead of doing this by callers,
move the debug output inside function.

In one case convert almost useless pr_debug() to dev_dbg() where
actual consumer of GPIO resource is disclosed.

Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Reviewed-by: Mika Westerberg <mika.westerberg@linux.intel.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
2017-11-30 10:53:51 +01:00
Andy Shevchenko 5870cff47b gpiolib: acpi: Move adev member to struct acpi_gpio_info
The further improvements are based on this change since
struct acpi_gpio_lookup is not available in some cases.

Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Reviewed-by: Mika Westerberg <mika.westerberg@linux.intel.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
2017-11-30 10:53:50 +01:00
Andrew Jeffery 2cbfca66ba gpio: Fix loose spelling
Literally.

I expect "lose" was meant here, rather than "loose", though you could feasibly
use a somewhat uncommon definition of "loose" to mean what would be meant by
"lose": "Loose the hounds" for instance, as in "Release the hounds".
Substituting in "value" for "hounds" gives "release the value", and makes some
sense, but futher substituting back to loose gives "loose the value" which
overall just seems a bit anachronistic.

Instead, use modern, pragmatic English and save a character.

Cc: Russell Currey <ruscur@russell.cc>
Signed-off-by: Andrew Jeffery <andrew@aj.id.au>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
2017-10-20 09:37:32 +02:00
Lukas Wunner eec1d566cd gpio: Introduce ->get_multiple callback
SPI-attached GPIO controllers typically read out all inputs in one go.
If callers desire the values of multipe inputs, ideally a single readout
should take place to return the desired values.  However the current
driver API only offers a ->get callback but no ->get_multiple (unlike
->set_multiple, which is present).  Thus, to read multiple inputs, a
full readout needs to be performed for every single value (barring
driver-internal caching), which is inefficient.

In fact, the lack of a ->get_multiple callback has been bemoaned
repeatedly by the gpio subsystem maintainer:
http://www.spinics.net/lists/linux-gpio/msg10571.html
http://www.spinics.net/lists/devicetree/msg121734.html

Introduce the missing callback.  Add corresponding consumer functions
such as gpiod_get_array_value().  Amend linehandle_ioctl() to take
advantage of the newly added infrastructure.  Update the documentation.

Cc: Rojhalat Ibrahim <imr@rtschenk.de>
Signed-off-by: Lukas Wunner <lukas@wunner.de>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
2017-10-19 22:32:39 +02:00
Masahiro Yamada 4a5c886e7c gpio: replace __maybe_unused in gpiolib.h with static inline
In header files, static inline is more commonly used.

Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
2017-08-14 15:01:12 +02:00
Andy Shevchenko a31f5c3a68 gpio: acpi: Override GPIO initialization flags
This allows ACPI GPIO code to modify flags based on
ACPI GpioIo() / GpioInt() resources.

Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Tested-by: Jarkko Nikula <jarkko.nikula@linux.intel.com>
Reviewed-by: Mika Westerberg <mika.westerberg@linux.intel.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
2017-05-29 11:21:44 +02:00
Andy Shevchenko c29fd9ebb2 gpiolib: Export gpiod_configure_flags() to internal users
This is preparatory patch for enabling GPIO ACPI to configure a pin
accordingly.

Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Tested-by: Jarkko Nikula <jarkko.nikula@linux.intel.com>
Reviewed-by: Mika Westerberg <mika.westerberg@linux.intel.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
2017-05-29 11:14:52 +02:00
Charles Keepax 05f479bf7d gpio: Add new flags to control sleep status of GPIOs
Add new flags to allow users to specify that they are not concerned with
the status of GPIOs whilst in a sleep/low power state.

Signed-off-by: Charles Keepax <ckeepax@opensource.wolfsonmicro.com>
Acked-by: Rob Herring <robh@kernel.org>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
2017-05-29 11:07:55 +02:00
Andy Shevchenko e567c35f49 gpiolib: Update documentation of struct acpi_gpio_info
It seems the code had been changed, but description left untouched.

Update description of the struct acpi_gpio_info and relative comments
accordingly.

Fixes: commit 52044723cd ("ACPI / gpio: Add irq_type when a GPIO is used as an interrupt")
Cc: Christophe RICARD <christophe.ricard@gmail.com>
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Acked-by: Mika Westerberg <mika.westerberg@linux.intel.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
2017-01-11 12:09:36 +01:00
Mika Westerberg 9427ecbed4 gpio: Rework of_gpiochip_set_names() to use device property accessors
In order to use "gpio-line-names" property in systems not having DT as
their boot firmware, rework of_gpiochip_set_names() to use device property
accessors. This reworked function is placed in a separate file making it
clear it deals with universal device properties.

Signed-off-by: Mika Westerberg <mika.westerberg@linux.intel.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
2016-10-24 16:33:11 +02:00
Linus Walleij e085294066 gpio: add missing static inline
of_get_named_gpiod_flags() was missing a static inline version
when compiling without OF_GPIO. Add this.

Reported-by: kbuild test robot <fengguang.wu@intel.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
2016-10-03 23:38:11 +02:00
Linus Walleij f4c1181f0f gpio: OF: localize some gpiochip init functions
of_gpiochip_add() and of_gpiochip_remove() are only used locally
in the gpio subsystem so move these functions to the local
header.

Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
2016-10-03 23:38:11 +02:00
Linus Walleij 031ba28a81 gpio: acpi: separation of concerns
The generic GPIO library directly implement code for acpi_find_gpio()
which is only used with CONFIG_ACPI. This was probably done because
OF did the same thing, but I removed that so remove this too.

Rename the internal acpi_find_gpio() in gpiolib-acpi.c to
acpi_populate_gpio_lookup() which seems to be more appropriate anyway
so as to avoid a namespace clash with the same function.

Make the stub return -ENOENT rather than -ENOSYS (as that is for
syscalls!).

For some reason the sunxi pin control driver was including the private
gpiolib header, it works just fine without it so remove that oneliner.

Cc: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Acked-by: Mika Westerberg <mika.westerberg@linux.intel.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
2016-10-03 23:38:10 +02:00
Linus Walleij ea713bc450 gpio: OF: separation of concerns
The generic GPIO library directly implement code for of_find_gpio()
which is only used with CONFIG_OF and causes compilation problems
on archs that do not even have stubs for OF functions, especially
on UM that does not implement any IO remap functions.

Move the function to gpiolib-of.c, implement a static inline stub
in gpiolib.h returning PTR_ERR(-ENOENT) if CONFIG_OF_GPIO is not
set and be done with it.

Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
2016-10-03 15:27:05 +02:00
Linus Walleij 44c7288f79 gpio: move gpiod_set_array_value_priv()
This renames gpiod_set_array_value_priv() to
gpiod_set_array_value_complex() and moves it to the gpiolib.h
private header file so we can reuse it in the subsystem.

Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
2016-04-26 10:51:36 +02:00
Linus Walleij df4878e969 gpio: store reflect the label to userspace
The gpio_chip label is useful for userspace to understand what
kind of GPIO chip it is dealing with. Let's store a copy of this
label in the gpio_device, add it to the struct passed to userspace
for GPIO_GET_CHIPINFO_IOCTL and modify lsgpio to show it.

Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
2016-02-19 09:48:41 +01:00
Linus Walleij 43c54ecade gpio: move the subdriver data pointer into gpio_device
We move to manage this pointer under gpiolib control rather than
leave it in the subdevice's gpio_chip. We can not NULL it after
gpiochip_remove so at to keep things tight.

Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
2016-02-16 00:20:02 +01:00
Linus Walleij 20ec3e39fc gpio: move the pin ranges into gpio_device
Instead of keeping this reference to the pin ranges in the
client driver-supplied gpio_chip, move it to the internal
gpio_device as the drivers have no need to inspect this.

Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
2016-02-16 00:20:02 +01:00
Linus Walleij fdeb8e1547 gpio: reflect base and ngpio into gpio_device
Some information about the GPIO chip need to stay around also
after the gpio_chip has been removed and only the gpio_device
persist. The base and ngpio are such things, for example we
don't want a new chip arriving to overlap the number space
of a dangling gpio_device, and the chardev may still query
the device for the number of lines etc.

Note that the code that assigns base and insert gpio_device
into the global list no longer check for a missing gpio_chip:
we respect the number space allocated by any other gpio_device.

As a consequence of the gdev being referenced directly from
the gpio_desc, we need to verify it differently from all
in-kernel API calls that fall through to direct queries to
the gpio_chip vtable: we first check that desc is !NULL, then
that desc->gdev is !NULL, then, if desc->gdev->chip is NULL,
we *BAIL OUT* without any error, so as to manage the case
where operations are requested on a device that is gone.

These checks were non-uniform and partly missing in the past:
so to simplify: create the macros VALIDATE_DESC() that will
return -EINVAL if the desc or desc->gdev is missing and just
0 if the chip is gone, and conversely VALIDATE_DESC_VOID()
for the case where the function does not return an error.
By using these macros, we get warning messages about missing
gdev with reference to the right function in the kernel log.

Despite the macro business this simplifies the code and make
it more readable than if we copy/paste the same descriptor
checking code into all code ABI call sites (IMHO).

Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
2016-02-11 20:29:46 +01:00
Linus Walleij 1c3cdb1861 gpio: move descriptors into gpio_device
We need gpio_device to hold the descriptors so that they can
be lifecycled with the struct gpio_device held from userspace.
Move the descriptor array into gpio_device. Also rename it from
"desc" (singularis) to "descs" (pluralis) to reflect the fact
that it is an array.

Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
2016-02-11 20:29:45 +01:00
Linus Walleij afbc4f312b gpio: move sysfs mock device to the gpio_device
Since gpio_device is the struct that survives if the backing
gpio_chip is removed, move the sysfs mock device to this state
container so it becomes part of the dangling state of the
GPIO device on removal.

Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
2016-02-11 18:16:54 +01:00
Linus Walleij 3c702e9987 gpio: add a userspace chardev ABI for GPIOs
A new chardev that is to be used for userspace GPIO access is
added in this patch. It is intended to gradually replace the
horribly broken sysfs ABI.

Using a chardev has many upsides:

- All operations are per-gpiochip, which is the actual
  device underlying the GPIOs, making us tie in to the
  kernel device model properly.

- Hotpluggable GPIO controllers can come and go, as this
  kind of problem has been know to userspace for character
  devices since ages, and if a gpiochip handle is held in
  userspace we know we will break something, whereas the
  sysfs is stateless.

- The one-value-per-file rule of sysfs is really hard to
  maintain when you want to twist more than one knob at a time,
  for example have in-kernel APIs to switch several GPIO
  lines at the same time, and this will be possible to do
  with a single ioctl() from userspace, saving a lot of
  context switching.

We also need to add a new bus type for GPIO. This is
necessary for example for userspace coldplug, where sysfs is
traversed to find the boot-time device nodes and create the
character devices in /dev.

This new chardev ABI is *non* *optional* and can be counted
on to be present in the future, emphasizing the preference
of this ABI.

The ABI only implements one single ioctl() to get the name
and number of GPIO lines of a chip. Even this is debatable:
see it as a minimal example for review. This ABI shall be
ruthlessly reviewed and etched in stone.

The old /sys/class/gpio is still optional to compile in,
but will be deprecated.

Unique device IDs are created using IDR, which is overkill
and insanely scalable, but also well tested.

Cc: Johan Hovold <johan@kernel.org>
Cc: Michael Welling <mwelling@ieee.org>
Cc: Markus Pargmann <mpa@pengutronix.de>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
2016-02-09 11:09:35 +01:00
Linus Walleij 34ffd85d9c gpio: refer to gpio device in prints and debugfs
We use the new struct device inside gpio_chip to related debug
prints and warnings, and we also add it to the debugfs dump.

Cc: Johan Hovold <johan@kernel.org>
Cc: Michael Welling <mwelling@ieee.org>
Cc: Markus Pargmann <mpa@pengutronix.de>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
2016-02-09 11:09:30 +01:00
Linus Walleij ff2b135922 gpio: make the gpiochip a real device
GPIO chips have been around for years, but were never real devices,
instead they were piggy-backing on a parent device (such as a
platform_device or amba_device) but this was always optional.
GPIO chips could also exist without any device at all, with its
struct device *parent (ex *dev) pointer being set to null.

When sysfs was in use, a mock device would be created, with the
optional parent assigned, or just floating orphaned with NULL
as parent.

If sysfs is active, it will use this device as parent.

We now create a gpio_device struct containing a real
struct device and move the subsystem over to using that. The
list of struct gpio_chip:s is augmented to hold struct
gpio_device:s and we find gpio_chips:s by first looking up
the struct gpio_device.

The struct gpio_device is designed to stay around even if the
gpio_chip is removed, so as to satisfy users in userspace
that need a backing data structure to hold the state of the
session initiated with e.g. a character device even if there is
no physical chip anymore.

From this point on, gpiochips are devices.

Cc: Johan Hovold <johan@kernel.org>
Cc: Michael Welling <mwelling@ieee.org>
Cc: Markus Pargmann <mpa@pengutronix.de>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
2016-02-09 11:03:53 +01:00