linux-toradex.git/drivers/gpio/gpiolib-cdev.c, branch v6.6

gpiolib: provide and use gpiod_line_state_notify()

2023-08-22T07:37:46+00:00

Wrap the calls to blocking_notifier_call_chain() for the line state
notifier with a helper that allows us to use fewer lines of code and
simpler syntax.

Signed-off-by: Bartosz Golaszewski 
Reviewed-by: Andy Shevchenko

gpio: cdev: wake up lineevent poll() on device unbind

2023-08-21T13:57:05+00:00

Add a notifier block to the lineevent_state structure and register it
with the gpio_device's device notifier. Upon reception of an event, wake
up the wait queue so that the user-space be forced out of poll() and
need to go into a new system call which will then fail due to the chip
being gone.

Signed-off-by: Bartosz Golaszewski 
Reviewed-by: Linus Walleij 
Reviewed-by: Kent Gibson

gpio: cdev: wake up linereq poll() on device unbind

2023-08-21T13:57:05+00:00

Add a notifier block to the linereq structure and register it with the
gpio_device's device notifier. Upon reception of an event, wake up the
wait queue so that the user-space be forced out of poll() and need to go
into a new system call which will then fail due to the chip being gone.

Signed-off-by: Bartosz Golaszewski 
Reviewed-by: Linus Walleij 
Reviewed-by: Kent Gibson

gpio: cdev: wake up chardev poll() on device unbind

2023-08-21T13:57:05+00:00

Add a notifier block to the gpio_chardev_data structure and register it
with the gpio_device's device notifier. Upon reception of an event, wake
up the wait queue so that the user-space be forced out of poll() and need
to go into a new system call which will then fail due to the chip being
gone.

Signed-off-by: Bartosz Golaszewski 
Reviewed-by: Linus Walleij 
Reviewed-by: Kent Gibson

gpiolib: add a second blocking notifier to struct gpio_device

2023-08-21T13:57:05+00:00

Add a new blocking notifier to struct gpio_device and use it to notify
subscribers about the GPIO device being unregistered from the device
model.

Signed-off-by: Bartosz Golaszewski 
Reviewed-by: Linus Walleij 
Reviewed-by: Kent Gibson

gpio: cdev: open-code to_gpio_chardev_data()

2023-08-21T13:57:05+00:00

This function is a wrapper around container_of(). It's used only once and
we will have a second notifier soon, so instead of having two flavors of
this helper, let's just open-code where needed.

Signed-off-by: Bartosz Golaszewski 
Reviewed-by: Linus Walleij 
Reviewed-by: Kent Gibson

gpiolib: rename the gpio_device notifier

2023-08-21T13:57:05+00:00

Change the generic "notifier" name to "line_state_notifier" in order to
reflect its purpose in preparation for adding a second notifier which
will be used to notify wait queues about device unregistering.

Signed-off-by: Bartosz Golaszewski 
Reviewed-by: Linus Walleij 
Reviewed-by: Kent Gibson

gpiolib: Introduce gpio_device_get() and gpio_device_put()

2023-01-30T14:55:29+00:00

Introduce gpio_device_get() and gpio_device_put() helpers
and convert existing users.

Signed-off-by: Andy Shevchenko 
Reviewed-by: Linus Walleij 
Signed-off-by: Bartosz Golaszewski

Merge tag 'gpio-updates-for-v6.2' of git://git.kernel.org/pub/scm/linux/kernel/git/brgl/linux

2022-12-15T17:45:51+00:00

Pull gpio updates from Bartosz Golaszewski:
 "We have a new GPIO multiplexer driver, bunch of driver updates and
  refactoring in the core GPIO library.

  GPIO core:
   - teach gpiolib to work with software nodes for HW description
   - remove ARCH_NR_GPIOS treewide as we no longer impose any limit on
     the number of GPIOS since the allocation became entirely dynamic
   - add support for HW quirks for Cirrus CS42L56 codec, Marvell NFC
     controller, Freescale PCIe and Ethernet controller, Himax LCDs and
     Mediatek mt2701
   - refactor OF quirk code
   - some general refactoring of the OF and ACPI code, adding new
     helpers, minor tweaks and fixes, making fwnode usage consistent
     etc.

  GPIO uAPI:
   - fix an issue where the user-space can trigger a NULL-pointer
     dereference in the kernel by opening a device file, forcing a
     driver unbind and then calling one of the syscalls on the
     associated file descriptor

  New drivers:
   - add gpio-latch: a new GPIO multiplexer based on latches connected
     to other GPIOs

  Driver updates:
   - convert i2c GPIO expanders to using .probe_new()
   - drop the gpio-sta2x11 driver
   - factor out common code for the ACCES IDIO-16 family of controllers
     and use this new library wherever applicable in drivers
   - add DT support to gpio-hisi
   - allow building gpio-davinci as a module and increase its maxItems
     property
   - add support for a new model to gpio-pca9570
   - other minor changes to various drivers"

* tag 'gpio-updates-for-v6.2' of git://git.kernel.org/pub/scm/linux/kernel/git/brgl/linux: (66 commits)
  gpio: sim: set a limit on the number of GPIOs
  gpiolib: protect the GPIO device against being dropped while in use by user-space
  gpiolib: cdev: fix NULL-pointer dereferences
  gpiolib: Provide to_gpio_device() helper
  gpiolib: Unify access to the device properties
  gpio: Do not include  when not really needed.
  gpio: pcf857x: Convert to i2c's .probe_new()
  gpio: pca953x: Convert to i2c's .probe_new()
  gpio: max732x: Convert to i2c's .probe_new()
  dt-bindings: gpio: gpio-davinci: Increase maxItems in gpio-line-names
  gpiolib: ensure that fwnode is properly set
  gpio: sl28cpld: Replace irqchip mask_invert with unmask_base
  gpiolib: of: Use correct fwnode for DT-probed chips
  gpiolib: of: Drop redundant check in of_mm_gpiochip_remove()
  gpiolib: of: Prepare of_mm_gpiochip_add_data() for fwnode
  gpiolib: add support for software nodes
  gpiolib: consolidate GPIO lookups
  gpiolib: acpi: avoid leaking ACPI details into upper gpiolib layers
  gpiolib: acpi: teach acpi_find_gpio() to handle data-only nodes
  gpiolib: acpi: change acpi_find_gpio() to accept firmware node
  ...

gpiolib: protect the GPIO device against being dropped while in use by user-space

2022-12-07T08:35:59+00:00

While any of the GPIO cdev syscalls is in progress, the kernel can call
gpiochip_remove() (for instance, when a USB GPIO expander is disconnected)
which will set gdev->chip to NULL after which any subsequent access will
cause a crash.

To avoid that: use an RW-semaphore in which the syscalls take it for
reading (so that we don't needlessly prohibit the user-space from calling
syscalls simultaneously) while gpiochip_remove() takes it for writing so
that it can only happen once all syscalls return.

Fixes: d7c51b47ac11 ("gpio: userspace ABI for reading/writing GPIO lines")
Fixes: 3c0d9c635ae2 ("gpiolib: cdev: support GPIO_V2_GET_LINE_IOCTL and GPIO_V2_LINE_GET_VALUES_IOCTL")
Fixes: aad955842d1c ("gpiolib: cdev: support GPIO_V2_GET_LINEINFO_IOCTL and GPIO_V2_GET_LINEINFO_WATCH_IOCTL")
Fixes: a54756cb24ea ("gpiolib: cdev: support GPIO_V2_LINE_SET_CONFIG_IOCTL")
Fixes: 7b8e00d98168 ("gpiolib: cdev: support GPIO_V2_LINE_SET_VALUES_IOCTL")
Signed-off-by: Bartosz Golaszewski 
[Nick: fixed a build failure with CDEV_V1 disabled]
Co-authored-by: Nick Hainke 
Reviewed-by: Kent Gibson 
Reviewed-by: Andy Shevchenko 
Reviewed-by: Linus Walleij