Move irq trigger flags, which as sysfs-interface specific, to the class
device data.
This avoids accessing the gpio-descriptor flags field using non-atomic
operations without any locking, and allows for a more clear separation
of the sysfs interface from gpiolib core.
Signed-off-by: Johan Hovold <johan@kernel.org>
Reviewed-by: Alexandre Courbot <acourbot@nvidia.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Remove FLAG_SYSFS_DIR, which is sysfs-interface specific, and store it
in the class-device data instead.
Note that the flag is only used during export.
Signed-off-by: Johan Hovold <johan@kernel.org>
Reviewed-by: Alexandre Courbot <acourbot@nvidia.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Rename active-low helper using common prefix.
Also remove unnecessary manipulation of value argument.
Signed-off-by: Johan Hovold <johan@kernel.org>
Reviewed-by: Alexandre Courbot <acourbot@nvidia.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Make sure to deregister the class device (and release the irq) while
holding the sysfs lock in gpio_unexport to prevent racing with
gpio_export.
Note that this requires the recently introduced per-gpio locking to
avoid a deadlock with the kernfs active protection when waiting for the
attribute operations to drain during deregistration.
Signed-off-by: Johan Hovold <johan@kernel.org>
Reviewed-by: Alexandre Courbot <acourbot@nvidia.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Add a per-gpio mutex to serialise attribute operations rather than use
one global mutex for all gpios and chips.
Having a single global lock for all gpios in a system adds unnecessary
latency to the sysfs interface, and especially when having gpio
controllers connected over slow buses.
Now that the global gpio-sysfs interrupt table is gone and with per-gpio
data in place, we can easily switch to using a more fine-grained locking
scheme.
Keep the global mutex to serialise the global (class) operations of gpio
export and unexport and chip removal.
Also document the locking assumptions made.
Note that this is also needed to fix a race between gpiod_export and
gpiod_unexport.
Signed-off-by: Johan Hovold <johan@kernel.org>
Reviewed-by: Alexandre Courbot <acourbot@nvidia.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Drop unnecessary locking from gpiod_export_link. If the class device has
not already been unregistered, class_find_device returns the ref-counted
class device so there's no need for locking.
Signed-off-by: Johan Hovold <johan@kernel.org>
Reviewed-by: Alexandre Courbot <acourbot@nvidia.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Only call irq helper if actually reconfiguring interrupt state.
This is a preparatory step in introducing separate gpio-irq request and
free functions.
Signed-off-by: Johan Hovold <johan@kernel.org>
Reviewed-by: Alexandre Courbot <acourbot@nvidia.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Store the value sysfs entry in the gpiod data rather than in a global
table accessed through an index stored in the overloaded gpio-descriptor
flag field.
Signed-off-by: Johan Hovold <johan@kernel.org>
Reviewed-by: Alexandre Courbot <acourbot@nvidia.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Add gpiod class-device data.
This is a first step in getting rid of the insane gpio-descriptor flag
overloading, backward irq-interface implementation, and course grained
sysfs-interface locking (a single static mutex for every operation on
all exported gpios in a system).
Signed-off-by: Johan Hovold <johan@kernel.org>
Reviewed-by: Alexandre Courbot <acourbot@nvidia.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
The attribute operations will never be called for an unregistered device
so remove redundant checks for FLAG_EXPORT.
Note that kernfs will also guarantee that any active sysfs operation has
finished before the attribute is removed during deregistration.
Signed-off-by: Johan Hovold <johan@kernel.org>
Reviewed-by: Alexandre Courbot <acourbot@nvidia.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Make sure to release any irq only after the class device has been
deregistered.
This avoids a race between gpiod_unexport and edge_store, where an irq
could be allocated just before the gpio class device is deregistered
without relying on FLAG_EXPORT and the global sysfs lock.
Note that there is no need to hold the sysfs lock when releasing the irq
after the class device is gone as kernfs will prevent further attribute
operations.
Signed-off-by: Johan Hovold <johan@kernel.org>
Reviewed-by: Alexandre Courbot <acourbot@nvidia.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Use DEVICE_ATTR_RO and DEVICE_ATTR_RW rather than specifying masks and
callbacks directly.
Signed-off-by: Johan Hovold <johan@kernel.org>
Reviewed-by: Alexandre Courbot <acourbot@nvidia.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Remove gpiod_sysfs_set_active_low (and gpio_sysfs_set_active_low) which
allowed code to change the polarity of a gpio line even after it had
been exported through sysfs.
Drivers should not care, and generally does not know, about gpio-line
polarity which is a hardware feature that needs to be described by
firmware.
It is currently possible to define gpio-line polarity in device-tree and
acpi firmware or using platform data. Userspace can also change the
polarity through sysfs.
Note that drivers using the legacy gpio interface could still use
GPIOF_ACTIVE_LOW to change the polarity before exporting the gpio.
There are no in-kernel users of this interface.
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Harry Wei <harryxiyou@gmail.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: linux-doc@vger.kernel.org
Cc: linux-kernel@zh-kernel.org
Cc: linux-arch@vger.kernel.org
Signed-off-by: Johan Hovold <johan@kernel.org>
Reviewed-by: Alexandre Courbot <acourbot@nvidia.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Rename the gpio-chip export/unexport functions to the more descriptive
names gpiochip_sysfs_register and gpiochip_sysfs_unregister.
Signed-off-by: Johan Hovold <johan@kernel.org>
Reviewed-by: Alexandre Courbot <acourbot@nvidia.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Clean gpio-chip class device registration and deregistration.
The class device is registered when a gpio-chip is added (or from
gpiolib_sysfs_init post-core init call), and deregistered when the chip
is removed.
Store the class device in struct gpio_chip directly rather than do a
class-device lookup on deregistration. This also removes the need for
the exported flag.
Signed-off-by: Johan Hovold <johan@kernel.org>
Reviewed-by: Alexandre Courbot <acourbot@nvidia.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Reduce scope of sysfs_lock protection during chip export and unexport,
which is only needed to prevent gpiod (re-)exports during chip removal.
Signed-off-by: Johan Hovold <johan@kernel.org>
Reviewed-by: Alexandre Courbot <acourbot@nvidia.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Put the recently introduced gpio-chip pointer to some more use in
gpiod_export.
Signed-off-by: Johan Hovold <johan@kernel.org>
Reviewed-by: Alexandre Courbot <acourbot@nvidia.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Drivers should call gpiochip_lock_as_irq (which prevents the pin
direction from being changed) in their irq_request_resources callbacks
but some drivers currently fail to do so.
Instead a second, explicit and often redundant call to lock-as-irq is
made by the sysfs-interface implementation after an irq has been
requested.
Move the explicit call before the irq-request to match the unlock done
after the irq is later released. Note that this also fixes an irq leak,
should the explicit call ever have failed.
Also add a comment about removing the redundant call once the broken
drivers have been fixed.
Signed-off-by: Johan Hovold <johan@kernel.org>
Reviewed-by: Alexandre Courbot <acourbot@nvidia.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Unregister GPIOs requested through sysfs at chip remove to avoid leaking
the associated memory and sysfs entries.
The stale sysfs entries prevented the gpio numbers from being exported
when the gpio range was later reused (e.g. at device reconnect).
This also fixes the related module-reference leak.
Note that kernfs makes sure that any on-going sysfs operations finish
before the class devices are unregistered and that further accesses
fail.
The chip exported flag is used to prevent gpiod exports during removal.
This also makes it harder to trigger, but does not fix, the related race
between gpiochip_remove and export_store, which is really a race with
gpiod_request that needs to be addressed separately.
Also note that this would prevent the crashes (e.g. NULL-dereferences)
at reconnect that affects pre-3.18 kernels, as well as use-after-free on
operations on open attribute files on pre-3.14 kernels (prior to
kernfs).
Fixes: d8f388d8dc ("gpio: sysfs interface")
Cc: stable <stable@vger.kernel.org> # v2.6.27: 01cca93a94
Signed-off-by: Johan Hovold <johan@kernel.org>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Fix memory leak in the gpio sysfs interface due to failure to drop
reference to device returned by class_find_device when setting the
gpio-line polarity.
Fixes: 0769746183 ("gpiolib: add support for changing value polarity
in sysfs")
Cc: stable <stable@vger.kernel.org> # v2.6.33
Signed-off-by: Johan Hovold <johan@kernel.org>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Fix memory leak in the gpio sysfs interface due to failure to drop
reference to device returned by class_find_device when creating a link.
Fixes: a4177ee7f1 ("gpiolib: allow exported GPIO nodes to be named
using sysfs links")
Cc: stable <stable@vger.kernel.org> # v2.6.32
Signed-off-by: Johan Hovold <johan@kernel.org>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Fix attribute-creation race with userspace by using the default group
to create also the contingent gpio device attributes.
Fixes: d8f388d8dc ("gpio: sysfs interface")
Signed-off-by: Johan Hovold <johan@kernel.org>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
The gpio device attributes were never destroyed when the gpio was
unexported (or on export failures).
Use device_create_with_groups() to create the default device attributes
of the gpio class device. Note that this also fixes the
attribute-creation race with userspace for these attributes.
Remove contingent attributes in export error path and on unexport.
Fixes: d8f388d8dc ("gpio: sysfs interface")
Cc: stable <stable@vger.kernel.org> # v2.6.27+
Signed-off-by: Johan Hovold <johan@kernel.org>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
The gpio-chip device attributes were never destroyed when the device was
removed.
Fix by using device_create_with_groups() to create the device attributes
of the chip class device.
Note that this also fixes the attribute-creation race with userspace.
Fixes: d8f388d8dc ("gpio: sysfs interface")
Cc: stable <stable@vger.kernel.org> # v2.6.27+
Signed-off-by: Johan Hovold <johan@kernel.org>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Although gpiod_get_direction() can be considered side-effect free for
consumers, its internals involve setting or clearing bits in the
affected GPIO descriptor, for which we need to force-cast the const
descriptor variable to non-const. This could lead to incorrect behavior
if the compiler decides to optimize here, so remove this const
attribute. The intent is to make gpiod_get_direction() private anyway,
so it does not really matter.
Reported-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Signed-off-by: Alexandre Courbot <acourbot@nvidia.com>
Acked-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
This function actually operates on a gpio_chip, so its prefix should
reflect that fact for consistency with other functions defined in
gpio/driver.h.
Signed-off-by: Alexandre Courbot <acourbot@nvidia.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
An iterator variable cannot be NULL in its loop.
Reported-by: Julia Lawall <julia.lawall@lip6.fr>
Signed-off-by: Alexandre Courbot <acourbot@nvidia.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
gpio_lock/unlock_as_irq() are working with (chip, offset) arguments and
are thus not using the old integer namespace. Therefore, there is no
reason to have gpiod variants of these functions working with
descriptors, especially since the (chip, offset) tuple is more suitable
to the users of these functions (GPIO drivers, whereas GPIO descriptors
are targeted at GPIO consumers).
Signed-off-by: Alexandre Courbot <acourbot@nvidia.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
For some reason gpiochip_export() would invalidate all the descriptors
of a chip if exporting it to sysfs failed. This does not appear as
necessary. Remove that part of the code.
While we are at it, add a note about the non-safety of temporarily
releasing a spinlock in the middle of the loop that protects its
iterator, and explain why this is done.
Signed-off-by: Alexandre Courbot <acourbot@nvidia.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
sysfs support is currently entangled within the core GPIO support, while
it should relly just be a (privileged) user of the integer GPIO API.
This patch is a first step towards making the gpiolib code more readable
by splitting it into logical parts.
Move all sysfs support to their own source file, and share static
members of gpiolib that need to be in the private gpiolib.h file. In
the future we will want to put some of them back into gpiolib.c, but this
first patch let us at least identify them.
Signed-off-by: Alexandre Courbot <acourbot@nvidia.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
