The current codebase makes use of the zero-length array language
extension to the C90 standard, but the preferred mechanism to declare
variable-length types such as these ones is a flexible array member[1][2],
introduced in C99:

struct foo {
        int stuff;
        struct boo array[];
};

By making use of the mechanism above, we will get a compiler warning
in case the flexible array does not occur last in the structure, which
will help us prevent some kind of undefined behavior bugs from being
inadvertently introduced[3] to the codebase from now on.

Also, notice that, dynamic memory allocations won't be affected by
this change:

"Flexible array members have incomplete type, and so the sizeof operator
may not be applied. As a quirk of the original implementation of
zero-length arrays, sizeof evaluates to zero."[1]

This issue was found with the help of Coccinelle.

[1] https://gcc.gnu.org/onlinedocs/gcc/Zero-Length.html
[2] https://github.com/KSPP/linux/issues/21
[3] commit 76497732932f ("cxgb3/l2t: Fix undefined behaviour")

Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com>
Link: https://lore.kernel.org/r/20200214171907.GA26588@embeddedor
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>

We have added polled mode to the normal input devices with the intent of
retiring input_polled_dev. This converts gpio_keys_polled driver to use
the polling mode of standard input devices and removes dependency on
INPUT_POLLDEV.

Note that we still keep polled and non-polled gpio-keys drivers separate,
as they are different enough and mixing them up would make the code pretty
confusing.

Acked-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Acked-by: Marco Felsch <m.felsch@pengutronix.de>
Link: https://lore.kernel.org/r/20191017204217.106453-9-dmitry.torokhov@gmail.com
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>

devm_fwnode_get_gpiod_from_child() is going away as the name is too
unwieldy, let's switch to using the new devm_fwnode_gpiod_get().

Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>

Sync up with mainline to resolve conflicts in iforce driver.

Instead of hardcoding the input name to the driver name
('gpio-keys-polled'), allow specifying the name of the device via
"label" property. If the property is not present (nor name is set in
board-supplied platform data), we'll default to the old name.

Signed-off-by: Enrico Weigelt, metux IT consult <info@metux.net>
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>

One of the more common cases of allocation size calculations is finding
the size of a structure that has a zero-sized array at the end, along
with memory for some number of elements for that array. For example:

struct gpio_keys_polled_dev {
	...
        struct gpio_keys_button_data data[0];
};

size = sizeof(struct gpio_keys_polled_dev) + count * sizeof(struct gpio_keys_button_data);
instance = devm_kzalloc(dev, size, GFP_KERNEL);

Instead of leaving these open-coded and prone to type mistakes, we can
now use the new struct_size() helper:

instance = devm_kzalloc(dev, struct_size(instance, data, count), GFP_KERNEL);

Notice that, in this case, variable size is not necessary, hence it
is removed.

This code was detected with the help of Coccinelle.

Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com>
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>

Based on 2 normalized pattern(s):

  this program is free software you can redistribute it and or modify
  it under the terms of the gnu general public license version 2 as
  published by the free software foundation

  this program is free software you can redistribute it and or modify
  it under the terms of the gnu general public license version 2 as
  published by the free software foundation #

extracted by the scancode license scanner the SPDX license identifier

  GPL-2.0-only

has been chosen to replace the boilerplate/reference in 4122 file(s).

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Enrico Weigelt <info@metux.net>
Reviewed-by: Kate Stewart <kstewart@linuxfoundation.org>
Reviewed-by: Allison Randal <allison@lohutok.net>
Cc: linux-spdx@vger.kernel.org
Link: https://lkml.kernel.org/r/20190604081206.933168790@linutronix.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Pull GPIO updates from Linus Walleij:
 "This is the bulk of GPIO changes for the v4.11 cycle

  Core changes:

   - Augment fwnode_get_named_gpiod() to configure the GPIO pin
     immediately after requesting it like all other APIs do. This is a
     treewide change also updating all users.

   - Pass a GPIO label down to gpiod_request() from
     fwnode_get_named_gpiod(). This makes debugfs and the userspace ABI
     correctly reflect the current in-kernel consumer of a pin taken
     using this abstraction. This is a treewide change also updating all
     users.

   - Rename devm_get_gpiod_from_child() to
     devm_fwnode_get_gpiod_from_child() to reflect the fact that this
     function is operating on a fwnode object. This is a treewide change
     also updating all users.

   - Make it possible to take multiple GPIOs in a single hog of device
     tree hogs.

   - The refactorings switching GPIO chips to use the .set_config()
     callback using standard pin control properties and providing a
     backend into the pin control subsystem that were also merged into
     the pin control tree naturally appear here too.

  Testing instrumentation:

   - A whole slew of cleanups and improvements to the mockup GPIO
     driver. We now have an extended userspace test exercising the
     subsystem, and we can inject interrupts etc from userspace to fully
     test the core GPIO functionality.

  New drivers:

   - New driver for the Cortina Systems Gemini GPIO controller.

   - New driver for the Exar XR17V352/354/358 chips.

   - New driver for the ACCES PCI-IDIO-16 PCI GPIO card.

  Driver changes:

   - RCAR: set the irqchip parent device, add fine-grained runtime PM
     support.

   - pca953x: support optional RESET control line on the chip.

   - DaVinci: cleanups and simplifications. Add support for multiple
     instances.

   - .set_multiple() and naming of lines on more or less all of the
     ISA/PCI GPIO controllers.

   - mcp23s08: refactored to use regmap as a first step to further
     rewrites and modernizations"

* tag 'gpio-v4.11-1' of git://git.kernel.org/pub/scm/linux/kernel/git/linusw/linux-gpio: (61 commits)
  gpio: reintroduce devm_get_gpiod_from_child()
  gpio: pci-idio-16: Fix PCI BAR index
  gpio: pci-idio-16: Fix PCI device ID code
  gpio: mockup: implement event injecting over debugfs
  gpio: mockup: add a dummy irqchip
  gpio: mockup: implement naming the lines
  gpio: mockup: code shrink
  gpio: mockup: readability tweaks
  gpio: Add GPIO support for the ACCES PCI-IDIO-16
  gpio: Add the devm_fwnode_get_index_gpiod_from_child() helper
  gpio: Rename devm_get_gpiod_from_child()
  gpio: mcp23s08: Select REGMAP/REGMAP_I2C to fix build error
  gpio: ws16c48: Add support for GPIO names
  gpio: gpio-mm: Add support for GPIO names
  gpio: 104-idio-16: Add support for GPIO names
  gpio: 104-idi-48: Add support for GPIO names
  gpio: 104-dio-48e: Add support for GPIO names
  gpio: ws16c48: Remove unnecessary driver_data set
  gpio: gpio-mm: Remove unnecessary driver_data set
  gpio: 104-idio-16: Remove unnecessary driver_data set
  ...

Rename devm_get_gpiod_from_child() into
devm_fwnode_get_gpiod_from_child() to reflect the fact that this
function is operating on a fwnode object.

Signed-off-by: Boris Brezillon <boris.brezillon@free-electrons.com>
Acked-by: Jacek Anaszewski <jacek.anaszewski@gmail.com>
Acked-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>

Currently all users of fwnode_get_named_gpiod() have no way to
specify a label for the GPIO. So GPIOs listed in debugfs are shown
with label "?". With this change a proper label is used.

Also adjust all users so they can pass a label, properly retrieved
from device tree properties.

Signed-off-by: Alexander Stein <alexander.stein@systec-electronic.com>
Cc: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Acked-by: Jacek Anaszewski <jacek.anaszewski@gmail.com>
Acked-by: Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>
Acked-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>