The bgpio_get_set() call should return a value clamped to [0,1],
the current code will return a negative value if reading
bit 31, which turns the value negative as this is a signed value
and thus gets interpreted as an error by the gpiolib core.
Found on the gpio-mxc but applies to any MMIO driver.

Cc: stable@vger.kernel.org # 4.3+
Cc: kernel@pengutronix.de
Cc: Vladimir Zapolskiy <vladimir_zapolskiy@mentor.com>
Fixes:  e20538b82f1f ("gpio: Propagate errors from chip->get()")
Reported-by: Clemens Gruber <clemens.gruber@pqgruber.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>

Returning an error instead of NULL in bgpio_map if
platform_get_resource_byname does not find a resource was introduced with
commit cf3f2a2c8bae ("gpio: generic: improve error handling in bgpio_map").
This results in several qemu runtime failures with default and non-default
configurations, if attempts are made to boot from mmcblk0. Examples for
failures with multi_v7_defconfig are

Machine: vexpress-a9	dtb: vexpress-v2p-ca9
Machine: vexpress-a15	dtb: vexpress-v2p-ca15-tc1

Crash:

VFS: Cannot open root device "mmcblk0" or unknown-block(0,0): error -6
Please append a correct "root=" boot option; here are the available partitions:
Kernel panic - not syncing: VFS: Unable to mount root fs on unknown-block(0,0)

Looking into the code, always returning an error if bgpio_map fails
does not appear to make much sense, since the code in bgpio_setup_io
specifically supports some of the resources to be NULL.

Fixes: cf3f2a2c8bae ("gpio: generic: improve error handling in bgpio_map")
Cc: Heiner Kallweit <hkallweit1@gmail.com>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>

Use the ERRPTR standard way to return an error code in a pointer
thus simplifiying the code.

Signed-off-by: Heiner Kallweit <hkallweit1@gmail.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>

Replace devm_request_mem_region / devm_ioremap with devm_ioremap_resource.

Signed-off-by: Heiner Kallweit <hkallweit1@gmail.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>

If bgpio_map returns NULL then err should always be set.

Signed-off-by: Heiner Kallweit <hkallweit1@gmail.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>

Allow chips to indicates that they are input-only and thus cannot set
the output value.  This will be used by the gpio-etraxfs driver.

Signed-off-by: Rabin Vincent <rabin@rab.in>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>

Allow to determine the current direction configuration by
reading back from the direction register.

Signed-off-by: Philipp Zabel <p.zabel@pengutronix.de>
Acked-by: Alexandre Courbot <acourbot@nvidia.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>

The change introduces BGPIOF_READ_OUTPUT_REG_SET flag for gpio-generic
GPIO chip implementation, which allows to get correct configured value
from reg_set register, input value is still get from reg_dat.

Signed-off-by: Vladimir Zapolskiy <vladimir_zapolskiy@mentor.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>

Add set_multiple functions to the generic driver for memory-mapped GPIO
controllers to improve performance when setting multiple outputs
simultaneously.

Signed-off-by: Rojhalat Ibrahim <imr@rtschenk.de>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>

Signed-off-by: abdoulaye berthe <berthe.ab@gmail.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>