Commit graph

115 commits

Author SHA1 Message Date
Bartosz Golaszewski
571c65bb2f gpiolib: add a common prefix to GPIO descriptor flags
While these flags are private within drivers/gpio/, when looking at the
code, it's not really clear they are GPIO-specific. Since these are GPIO
descriptor flags, prepend their names with a common "GPIOD" prefix.

While at it: update the flags' docs: make spelling consistent, correct
outdated information, etc.

Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Link: https://lore.kernel.org/r/20250909-rename-gpio-flags-v1-1-bda208a40856@linaro.org
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
2025-09-12 09:20:38 +02:00
Dan Carpenter
5607f5ed3c gpio: sysfs: Fix an end of loop test in gpiod_unexport()
The test for "if (!desc_data)" does not work correctly because the list
iterator in a list_for_each_entry() loop is always non-NULL. If we don't
exit via a break, then it points to invalid memory.  Instead, use a tmp
variable for the list iterator and only set the "desc_data" when we have
found a match.

Fixes: 1cd53df733 ("gpio: sysfs: don't look up exported lines as class devices")
Signed-off-by: Dan Carpenter <dan.carpenter@linaro.org>
Link: https://lore.kernel.org/r/747545bf-05f0-4f89-ba77-cb96bf9041f1@sabinyo.mountain
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
2025-07-19 18:06:47 +02:00
Bartosz Golaszewski
e69c6db4cd gpio: sysfs: allow disabling the legacy parts of the GPIO sysfs interface
Add a Kconfig switch allowing to disable the legacy parts of the GPIO
sysfs interface. This means that even though we keep the
/sys/class/gpio/ directory, it no longer contains the global
export/unexport attribute pair (instead, the user should use the
per-chip export/unpexport) nor the gpiochip$BASE entries. This option
default to y if GPIO sysfs is enabled but we'll default it to n at some
point in the future.

Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Link: https://lore.kernel.org/r/20250704-gpio-sysfs-chip-export-v4-9-9289d8758243@linaro.org
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
2025-07-16 10:27:08 +02:00
Bartosz Golaszewski
4fa93223e0 gpio: sysfs: export the GPIO directory locally in the gpiochip<id> directory
As a way to allow the user-space to stop referring to GPIOs by their
global numbers, introduce a parallel group of line attributes for
exported GPIO that live inside the GPIO chip class device and are
referred to by their HW offset within their parent chip.

Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Link: https://lore.kernel.org/r/20250704-gpio-sysfs-chip-export-v4-8-9289d8758243@linaro.org
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
2025-07-16 10:27:08 +02:00
Bartosz Golaszewski
1cd53df733 gpio: sysfs: don't look up exported lines as class devices
In preparation for adding a parallel, per-chip attribute group for
exported GPIO lines, stop using class device APIs to refer to it in the
code. When unregistering the chip, don't call class_find_device() but
instead store exported lines in a linked list inside the GPIO chip data
object and look it up there.

Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Link: https://lore.kernel.org/r/20250704-gpio-sysfs-chip-export-v4-7-9289d8758243@linaro.org
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
2025-07-16 10:27:08 +02:00
Bartosz Golaszewski
f7d4fb62d0 gpio: sysfs: don't use driver data in sysfs callbacks for line attributes
Currently each exported GPIO is represented in sysfs as a separate class
device. This allows us to simply use dev_get_drvdata() to retrieve the
pointer passed to device_create_with_groups() from sysfs ops callbacks.

However, we're preparing to add a parallel set of per-line sysfs
attributes that will live inside the associated gpiochip group. They are
not registered as class devices and so have the parent device passed as
argument to their callbacks (the GPIO chip class device).

Put the attribute structs inside the GPIO descriptor data and
dereference the relevant ones using container_of() in the callbacks.
This way, we'll be able to reuse the same code for both the legacy and
new GPIO attributes.

Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Link: https://lore.kernel.org/r/20250704-gpio-sysfs-chip-export-v4-6-9289d8758243@linaro.org
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
2025-07-16 10:27:07 +02:00
Bartosz Golaszewski
12faec7ed1 gpio: sysfs: rename the data variable in gpiod_(un)export()
In preparation for future commits which will make use of descriptor AND
GPIO-device data in the same functions rename the former from data to
desc_data separately which will make future changes smaller and easier
to read.

Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Link: https://lore.kernel.org/r/20250704-gpio-sysfs-chip-export-v4-5-9289d8758243@linaro.org
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
2025-07-16 10:27:07 +02:00
Bartosz Golaszewski
7c49c1298f gpio: sysfs: pass gpiod_data directly to internal GPIO sysfs functions
We don't use any fields from struct device in gpio_sysfs_request_irq(),
gpio_sysfs_free_irq() and gpio_sysfs_set_active_low(). We only use the
dev argument to get the associated struct gpiod_data pointer with
dev_get_drvdata().

To make the transition to not using dev_get_drvdata() across line
callbacks for sysfs attributes easier, pass gpiod_data directly to
these functions instead of having it wrapped in struct device.

Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Link: https://lore.kernel.org/r/20250704-gpio-sysfs-chip-export-v4-4-9289d8758243@linaro.org
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
2025-07-16 10:27:07 +02:00
Bartosz Golaszewski
c38c3a349b gpio: sysfs: only get the dirent reference for the value attr once
There's no reason to retrieve the reference to the sysfs dirent every
time we request an interrupt, we can as well only do it once when
exporting the GPIO.

Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Link: https://lore.kernel.org/r/20250704-gpio-sysfs-chip-export-v4-3-9289d8758243@linaro.org
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
2025-07-16 10:27:07 +02:00
Bartosz Golaszewski
2028f854b3 gpio: sysfs: add a parallel class device for each GPIO chip using device IDs
In order to enable moving away from the global GPIO numberspace-based
exporting of lines over sysfs: add a parallel, per-chip entry under
/sys/class/gpio/ for every registered GPIO chip, denoted by device ID
in the file name and not its base GPIO number.

Compared to the existing chip group: it does not contain the "base"
attribute as the goal of this change is to not refer to GPIOs by their
global number from user-space anymore. It also contains its own,
per-chip export/unexport attribute pair which allow to export lines by
their hardware offset within the chip.

Caveat #1: the new device cannot be a link to (or be linked to by) the
existing "gpiochip<BASE>" entry as we cannot create links in
/sys/class/xyz/.

Caveat #2: the new entry cannot be named "gpiochipX" as it could
conflict with devices whose base is statically defined to a low number.
Let's go with "chipX" instead.

While at it: the chip label is unique so update the untrue statement
when extending the docs.

Acked-by: Linus Walleij <linus.walleij@linaro.org>
Link: https://lore.kernel.org/r/20250704-gpio-sysfs-chip-export-v4-2-9289d8758243@linaro.org
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
2025-07-16 10:27:07 +02:00
Bartosz Golaszewski
32ad0b9a17 gpio: sysfs: use gpiod_is_equal() to compare GPIO descriptors
We have a dedicated comparator for GPIO descriptors that performs
additional checks and hides the implementation detail of whether the
same GPIO can be associated with two separate struct gpio_desc objects.
Use it in sysfs code

Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Link: https://lore.kernel.org/r/20250704-gpio-sysfs-chip-export-v4-1-9289d8758243@linaro.org
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
2025-07-16 10:27:07 +02:00
Antonio Quartulli
e6bb78570f gpio: sysfs: fix use-after-free in error path
When invoking device_create_with_groups(), its return value is stored
in `data->cdev_base`. However, in case of faiure, `data` is first freed
and then derefernced in order to return `data->cdev_base`.

Fix the use-after-free by extracting the error code before free'ing
`data`.

Fixes: fd19792851 ("gpio: sysfs: remove the mockdev pointer from struct gpio_device")
Addresses-Coverity-ID: 1644512 ("Memory - illegal accesses  (USE_AFTER_FREE)")
Signed-off-by: Antonio Quartulli <antonio@mandelbit.com>
Link: https://lore.kernel.org/r/20250622220221.28025-1-antonio@mandelbit.com
[Bartosz: added Fixes: tag, tweaked commit message]
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
2025-06-23 09:14:15 +02:00
Bartosz Golaszewski
fd19792851 gpio: sysfs: remove the mockdev pointer from struct gpio_device
The usage of the mockdev pointer in struct gpio_device is limited to the
GPIO sysfs code. There's no reason to keep it in this top-level
structure. Create a separate structure containing the reference to the
GPIO device and the dummy class device that will be passed to
device_create_with_groups(). The !gdev->mockdev checks can be removed as
long as we make sure that all operations on the GPIO class are protected
with the sysfs lock.

Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Link: https://lore.kernel.org/r/20250610-gpio-sysfs-chip-export-v1-6-a8c7aa4478b1@linaro.org
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
2025-06-20 09:29:15 +02:00
Bartosz Golaszewski
982ec96c38 gpio: sysfs: remove unneeded headers
No symbols from the linux/idr.h or linux/spinlock.h headers are used in
this file so remove them. We also don't technically need linux/list.h
currently but one of the follow-up commits will start using it so let's
leave it.

Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Link: https://lore.kernel.org/r/20250610-gpio-sysfs-chip-export-v1-5-a8c7aa4478b1@linaro.org
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
2025-06-20 09:29:14 +02:00
Bartosz Golaszewski
dc665b5248 gpio: sysfs: refactor the coding style
Update the code to be more consistent with the rest of the codebase.
Mostly correctly align line-breaks, remove unneeded tabs, stray newlines
& spaces and tweak the comment style.

No functional change.

Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Link: https://lore.kernel.org/r/20250610-gpio-sysfs-chip-export-v1-4-a8c7aa4478b1@linaro.org
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
2025-06-20 09:29:14 +02:00
Bartosz Golaszewski
e1f02b40a7 gpio: sysfs: call mutex_destroy() in gpiod_unexport()
While not critical, it's useful to have the corresponding call to
mutex_destroy() whenever we use mutex_init(). Add the call right before
kfreeing the GPIO data.

Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Link: https://lore.kernel.org/r/20250610-gpio-sysfs-chip-export-v1-3-a8c7aa4478b1@linaro.org
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
2025-06-20 09:29:14 +02:00
Bartosz Golaszewski
92ac7de317 gpiolib: don't allow setting values on input lines
Some drivers as well as the character device and sysfs code check
whether the line actually is in output mode before allowing the user to
set a value.

However, GPIO value setters now return integer values and can indicate
failures. This allows us to move these checks into the core code.

Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Link: https://lore.kernel.org/r/20250311-gpio-set-check-output-v1-1-d971bca9e6fa@linaro.org
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
2025-04-07 09:00:48 +02:00
Bartosz Golaszewski
7b925098c9 gpio: sysfs: emit chardev line-state events on edge store
In order to emit line-state events on edge changes in sysfs, update the
EDGE flags in the descriptor in gpio_sysfs_request_irq() and emit the
event on a successful store.

Reviewed-by: Kent Gibson <warthog618@gmail.com>
Link: https://lore.kernel.org/r/20241031-gpio-notify-sysfs-v4-5-142021c2195c@linaro.org
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
2024-11-04 08:56:20 +01:00
Bartosz Golaszewski
5a7119e0d9 gpio: sysfs: emit chardev line-state events on active-low changes
The sysfs active_low attribute doesn't go through the usual paths so it
doesn't emit the line-state event. Add the missing call to
gpiod_line_state_notify() to gpio_sysfs_set_active_low().

Reviewed-by: Kent Gibson <warthog618@gmail.com>
Link: https://lore.kernel.org/r/20241031-gpio-notify-sysfs-v4-4-142021c2195c@linaro.org
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
2024-11-04 08:56:19 +01:00
Bartosz Golaszewski
285678c947 gpio: sysfs: emit chardev line-state events on GPIO export
We already emit a CONFIG_RELEASED event when a line is unexported over
sysfs (this is handled by gpiod_free()) but we don't do the opposite
when it's exported. This adds the missing call to
gpiod_line_state_notify().

Reviewed-by: Kent Gibson <warthog618@gmail.com>
Link: https://lore.kernel.org/r/20241031-gpio-notify-sysfs-v4-3-142021c2195c@linaro.org
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
2024-11-04 08:56:19 +01:00
Bartosz Golaszewski
f4af1671c2 gpio: sysfs: use cleanup guards for the sysfs_lock mutex
Shrink the code and remove some goto labels by using guards around the
sysfs_lock mutex.

Reviewed-by: Kent Gibson <warthog618@gmail.com>
Link: https://lore.kernel.org/r/20241031-gpio-notify-sysfs-v4-2-142021c2195c@linaro.org
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
2024-11-04 08:56:19 +01:00
Bartosz Golaszewski
d99c980cfe gpio: sysfs: use cleanup guards for gpiod_data::mutex
Shrink the code and drop some goto labels by using lock guards around
gpiod_data::mutex.

Reviewed-by: Kent Gibson <warthog618@gmail.com>
Link: https://lore.kernel.org/r/20241031-gpio-notify-sysfs-v4-1-142021c2195c@linaro.org
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
2024-11-04 08:56:19 +01:00
Bartosz Golaszewski
37d5a6d6f4 gpio: sysfs: demote warning messages on invalid user input to debug
We should not emit a non-ratelimited warning everytime a user passes an
invalid value to /sys/class/gpio/export as it's an easy way to spam the
kernel log. Change the relevant messages to pr_debug_ratelimited().

Link: https://lore.kernel.org/r/20241021185717.96449-1-brgl@bgdev.pl
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
2024-10-31 13:34:13 +01:00
Bartosz Golaszewski
b6f7aeaf1b gpio: sysfs: constify gpio class
All class functions used here take a const pointer to the class
structure. We can constify gpio_class.

While at it: remove a stray newline and use a tab in the struct
definition for consistency with the line above.

Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Link: https://lore.kernel.org/r/20241014121831.106532-1-brgl@bgdev.pl
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
2024-10-17 08:53:02 +02:00
Bartosz Golaszewski
700cdf7ed0 gpio: sysfs: make the sysfs export behavior consistent
For drivers or board files that set gpio_chip->names, the links to the
GPIO attribute group created on sysfs export will be named after the
line's name set in that array. For lines that are named using device
properties, the names pointer of the gpio_chip struct is never assigned
so they are exported as if they're not named.

The ABI documentation does not mention the former behavior and given
that the majority of modern systems use device-tree, ACPI or other way
of passing GPIO names using device properties - bypassing gc->names -
it's better to make the behavior consistent by always exporting lines as
"gpioXYZ".

Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Link: https://lore.kernel.org/r/20240930083029.17694-1-brgl@bgdev.pl
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
2024-10-02 16:30:12 +02:00
Andy Shevchenko
94bd9ce160 gpiolib: Update the kernel documentation - add Return sections
$ scripts/kernel-doc -v -none -Wall drivers/gpio/gpiolib* 2>&1 | grep -w warning | wc -l
67

Fix these by adding Return sections. While at it, make sure all of
Return sections use the same style.

Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Reviewed-by: Randy Dunlap <rdunlap@infradead.org>
Tested-by: Randy Dunlap <rdunlap@infradead.org>
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Link: https://lore.kernel.org/r/20240828164449.2777666-1-andriy.shevchenko@linux.intel.com
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
2024-09-02 12:27:36 +02:00
Andy Shevchenko
8a7a610325 gpiolib: Get rid of never false gpio_is_valid() calls
In the cases when gpio_is_valid() is called with unsigned parameter
the result is always true in the GPIO library code, hence the check
for false won't ever be true. Get rid of such calls.

While at it, move GPIO device base to be unsigned to clearly show
it won't ever be negative. This requires a new definition for the
maximum GPIO number in the system.

Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
2024-04-17 22:46:44 +02:00
Alexander Sverdlin
8636f19c2d gpio: sysfs: repair export returning -EPERM on 1st attempt
It would make sense to return -EPERM if the bit was already set (already
used), not if it was cleared. Before this fix pins can only be exported on
the 2nd attempt:

$ echo 522 > /sys/class/gpio/export
sh: write error: Operation not permitted
$ echo 522 > /sys/class/gpio/export

Fixes: 35b545332b ("gpio: remove gpio_lock")
Signed-off-by: Alexander Sverdlin <alexander.sverdlin@gmail.com>
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
2024-03-08 10:32:00 +01:00
Bartosz Golaszewski
be91c19e47 gpio: sysfs: fix inverted pointer logic
The logic is inverted, we want to return if the chip *IS* NULL.

Fixes: d83cee3d2b ("gpio: protect the pointer to gpio_chip in gpio_device with SRCU")
Reported-by: Dan Carpenter <dan.carpenter@linaro.org>
Closes: https://lore.kernel.org/linux-gpio/15671341-0b29-40e0-b487-0a4cdc414d8e@moroto.mountain/
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
2024-02-15 08:40:40 +01:00
Bartosz Golaszewski
d82b9e0887 gpio: use srcu_dereference() with SRCU-protected pointers
Lockdep with CONFIG_PROVE_RCU enabled reports false positives about
suspicious rcu_dereference() usage. Let's silence it by using
srcu_dereference() which is the correct helper with SRCU.

Fixes: d83cee3d2b ("gpio: protect the pointer to gpio_chip in gpio_device with SRCU")
Reported-by: kernel test robot <oliver.sang@intel.com>
Closes: https://lore.kernel.org/oe-lkp/202402122234.d85cca9b-lkp@intel.com
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
Acked-by: Paul E. McKenney <paulmck@kernel.org>
2024-02-15 08:39:25 +01:00
Bartosz Golaszewski
d83cee3d2b gpio: protect the pointer to gpio_chip in gpio_device with SRCU
Ensure we cannot crash if the GPIO device gets unregistered (and the
chip pointer set to NULL) during any of the API calls.

To that end: wait for all users of gdev->chip to exit their read-only
SRCU critical sections in gpiochip_remove().

For brevity: add a guard class which can be instantiated at the top of
every function requiring read-only access to the chip pointer and use it
in all API calls taking a GPIO descriptor as argument. In places where
we only deal with the GPIO device - use regular guard() helpers and
rcu_dereference() for chip access. Do the same in API calls taking a
const pointer to gpio_desc.

Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Acked-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
2024-02-12 11:00:31 +01:00
Bartosz Golaszewski
5694f274a0 gpio: sysfs: don't access gdev->chip if it's not needed
Don't dereference gdev->chip if the same information can be obtained
from struct gpio_device.

Suggested-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Acked-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
2024-02-12 10:51:13 +01:00
Bartosz Golaszewski
b93bca4bd6 gpio: sysfs: pass the GPIO device - not chip - to sysfs callbacks
We're working towards protecting the chip pointer in struct gpio_device
with SRCU. In order to use it in sysfs callbacks we must pass the pointer
to the GPIO device that wraps the chip instead of the address of the
chip itself as the user data.

Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Acked-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
2024-02-12 10:50:58 +01:00
Bartosz Golaszewski
59cba4a0e6 gpio: sysfs: extend the critical section for unregistering sysfs devices
Checking the gdev->mockdev pointer for NULL must be part of the critical
section.

Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Acked-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
2024-02-12 10:50:55 +01:00
Bartosz Golaszewski
35b545332b gpio: remove gpio_lock
The "multi-function" gpio_lock is pretty much useless with how it's used
in GPIOLIB currently. Because many GPIO API calls can be called from all
contexts but may also call into sleeping driver callbacks, there are
many places with utterly broken workarounds like yielding the lock to
call a possibly sleeping function and then re-acquiring it again without
taking into account that the protected state may have changed.

It was also used to protect several unrelated things: like individual
descriptors AND the GPIO device list. We now serialize access to these
two with SRCU and so can finally remove the spinlock.

There is of course the question of consistency of lockless access to
GPIO descriptors. Because we only support exclusive access to GPIOs
(officially anyway, I'm looking at you broken
GPIOD_FLAGS_BIT_NONEXCLUSIVE bit...) and the API contract with providers
does not guarantee serialization, it's enough to ensure we cannot
accidentally dereference an invalid pointer and that the state we present
to both users and providers remains consistent. To achieve that: read the
flags field atomically except for a few special cases. Read their current
value before executing callback code and use this value for any subsequent
logic. Modifying the flags depends on the particular use-case and can
differ. For instance: when requesting a GPIO, we need to set the
REQUESTED bit immediately so that the next user trying to request the
same line sees -EBUSY.

While at it: the allocations that used GFP_ATOMIC until this point can
now switch to GFP_KERNEL.

Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Acked-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
2024-02-12 10:50:45 +01:00
Bartosz Golaszewski
2a9101e875 gpio: sysfs: use gpio_device_find() to iterate over existing devices
With the list of GPIO devices now protected with SRCU we can use
gpio_device_find() to traverse it from sysfs.

Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Acked-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
2024-02-12 10:50:42 +01:00
Bartosz Golaszewski
efb8235bfd gpiolib: revert the attempt to protect the GPIO device list with an rwsem
This reverts commits 1979a28075 ("gpiolib: replace the GPIO device
mutex with a read-write semaphore") and 65a828bab1 ("gpiolib: use
a mutex to protect the list of GPIO devices").

Unfortunately the legacy GPIO API that's still used in older code has to
translate numbers from the global GPIO numberspace to descriptors. This
results in a GPIO device lookup in every call to legacy functions. Some
of those functions - like gpio_set/get_value() - can be called from
atomic context so taking a sleeping lock that is an RW semaphore results
in an error.

We'll probably have to protect this list with SRCU.

Reported-by: Dan Carpenter <dan.carpenter@linaro.org>
Closes: https://lore.kernel.org/linux-wireless/f7b5ff1e-8f34-4d98-a7be-b826cb897dc8@moroto.mountain/
Fixes: 1979a28075 ("gpiolib: replace the GPIO device mutex with a read-write semaphore")
Fixes: 65a828bab1 ("gpiolib: use a mutex to protect the list of GPIO devices")
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
2024-01-17 09:52:37 +01:00
Bartosz Golaszewski
1979a28075 gpiolib: replace the GPIO device mutex with a read-write semaphore
There are only two spots where we modify (add to or remove objects from)
the GPIO device list. Readers should be able to access it concurrently.
Replace the mutex with a read-write semaphore and adjust the locking
operations accordingly.

Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
2024-01-04 10:29:16 +01:00
Bartosz Golaszewski
513246a34b gpio: sysfs: drop tabs from local variable declarations
Older code has an annoying habit of putting tabs between the type and the
name of the variable. This doesn't really add to readability and newer
code doesn't do it so make the entire file consistent.

Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
2023-12-27 16:01:37 +01:00
Bartosz Golaszewski
4ccdaba5ab Linux 6.7-rc7
-----BEGIN PGP SIGNATURE-----
 
 iQFSBAABCAA8FiEEq68RxlopcLEwq+PEeb4+QwBBGIYFAmWHepQeHHRvcnZhbGRz
 QGxpbnV4LWZvdW5kYXRpb24ub3JnAAoJEHm+PkMAQRiGm6YH/0b9hMQ1f2DbMjEq
 w8h0bIMkc+Jv9fLVgCMA8nTuAQsYNp+MJ8PKA9t8CCtG1BTs+lXr6DsN2GpoODEj
 fMCXzyHTlMgg5S0iXAXHcxX1t1gRDgxoOeBvUY8YZw1JZriNsO+dF3U7rRdrmg1n
 7jq6WFxJfuB2NMlmys7vk/0c3t193AKxkWyDFBmiim3MX0IYxGlD5DVadaxA6Vx7
 Pqjt9ljVG11jJWeQ9ZFLd5RmZkdmY/JVlPagEr5rPDsJrbL23sLUu4bRHGBWcipU
 BgBUdj7K6tahuwKeg2KENxCGjvQOaFIti1l1CvHMWKPgFFlhE30DD6x7nZldPSj6
 m52I1xE=
 =tLIr
 -----END PGP SIGNATURE-----

Merge tag 'v6.7-rc7' into gpio/for-next

Linux 6.7-rc7
2023-12-27 15:41:04 +01:00
Bartosz Golaszewski
65a828bab1 gpiolib: use a mutex to protect the list of GPIO devices
The global list of GPIO devices is never modified or accessed from
atomic context so it's fine to protect it using a mutex. Add a new
global lock dedicated to the gpio_devices list and use it whenever
accessing or modifying it.

Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
2023-12-18 10:00:43 +01:00
Boerge Struempfel
95dd1e34ff gpiolib: sysfs: Fix error handling on failed export
If gpio_set_transitory() fails, we should free the GPIO again. Most
notably, the flag FLAG_REQUESTED has previously been set in
gpiod_request_commit(), and should be reset on failure.

To my knowledge, this does not affect any current users, since the
gpio_set_transitory() mainly returns 0 and -ENOTSUPP, which is converted
to 0. However the gpio_set_transitory() function calles the .set_config()
function of the corresponding GPIO chip and there are some GPIO drivers in
which some (unlikely) branches return other values like -EPROBE_DEFER,
and -EINVAL. In these cases, the above mentioned FLAG_REQUESTED would not
be reset, which results in the pin being blocked until the next reboot.

Fixes: e10f72bf4b ("gpio: gpiolib: Generalise state persistence beyond sleep")
Signed-off-by: Boerge Struempfel <boerge.struempfel@gmail.com>
Reviewed-by: Andy Shevchenko <andy@kernel.org>
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
2023-12-01 10:44:48 +01:00
Bartosz Golaszewski
e404b0cc9f gpio: sysfs: drop the mention of gpiochip_find() from sysfs code
We have removed all callers of gpiochip_find() so don't mention it in
gpiolib-sysfs.c.

Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
2023-10-04 13:36:23 +02:00
Andy Shevchenko
20d9b3b5f2 gpiolib: sysfs: Do unexport GPIO when user asks for it
It seems that sysfs interface implicitly relied on the gpiod_free() to
unexport the line. This is logically incorrect as core gpiolib should
not deal with sysfs so instead of restoring it, let's call
gpiod_unexport() from sysfs code.

Fixes: b0ce9ce408 ("gpiolib: Do not unexport GPIO on freeing")
Reported-by: Marek BehĂșn <kabel@kernel.org>
Closes: https://lore.kernel.org/r/20230808102828.4a9eac09@dellmb
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Tested-by: Marek BehĂșn <kabel@kernel.org>
[Bartosz: tweaked the commit message]
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
2023-08-16 13:34:31 +02:00
Linus Torvalds
556eb8b791 Driver core changes for 6.4-rc1
Here is the large set of driver core changes for 6.4-rc1.
 
 Once again, a busy development cycle, with lots of changes happening in
 the driver core in the quest to be able to move "struct bus" and "struct
 class" into read-only memory, a task now complete with these changes.
 
 This will make the future rust interactions with the driver core more
 "provably correct" as well as providing more obvious lifetime rules for
 all busses and classes in the kernel.
 
 The changes required for this did touch many individual classes and
 busses as many callbacks were changed to take const * parameters
 instead.  All of these changes have been submitted to the various
 subsystem maintainers, giving them plenty of time to review, and most of
 them actually did so.
 
 Other than those changes, included in here are a small set of other
 things:
   - kobject logging improvements
   - cacheinfo improvements and updates
   - obligatory fw_devlink updates and fixes
   - documentation updates
   - device property cleanups and const * changes
   - firwmare loader dependency fixes.
 
 All of these have been in linux-next for a while with no reported
 problems.
 
 Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
 -----BEGIN PGP SIGNATURE-----
 
 iG0EABECAC0WIQT0tgzFv3jCIUoxPcsxR9QN2y37KQUCZEp7Sw8cZ3JlZ0Brcm9h
 aC5jb20ACgkQMUfUDdst+ykitQCfamUHpxGcKOAGuLXMotXNakTEsxgAoIquENm5
 LEGadNS38k5fs+73UaxV
 =7K4B
 -----END PGP SIGNATURE-----

Merge tag 'driver-core-6.4-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/driver-core

Pull driver core updates from Greg KH:
 "Here is the large set of driver core changes for 6.4-rc1.

  Once again, a busy development cycle, with lots of changes happening
  in the driver core in the quest to be able to move "struct bus" and
  "struct class" into read-only memory, a task now complete with these
  changes.

  This will make the future rust interactions with the driver core more
  "provably correct" as well as providing more obvious lifetime rules
  for all busses and classes in the kernel.

  The changes required for this did touch many individual classes and
  busses as many callbacks were changed to take const * parameters
  instead. All of these changes have been submitted to the various
  subsystem maintainers, giving them plenty of time to review, and most
  of them actually did so.

  Other than those changes, included in here are a small set of other
  things:

   - kobject logging improvements

   - cacheinfo improvements and updates

   - obligatory fw_devlink updates and fixes

   - documentation updates

   - device property cleanups and const * changes

   - firwmare loader dependency fixes.

  All of these have been in linux-next for a while with no reported
  problems"

* tag 'driver-core-6.4-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/driver-core: (120 commits)
  device property: make device_property functions take const device *
  driver core: update comments in device_rename()
  driver core: Don't require dynamic_debug for initcall_debug probe timing
  firmware_loader: rework crypto dependencies
  firmware_loader: Strip off \n from customized path
  zram: fix up permission for the hot_add sysfs file
  cacheinfo: Add use_arch[|_cache]_info field/function
  arch_topology: Remove early cacheinfo error message if -ENOENT
  cacheinfo: Check cache properties are present in DT
  cacheinfo: Check sib_leaf in cache_leaves_are_shared()
  cacheinfo: Allow early level detection when DT/ACPI info is missing/broken
  cacheinfo: Add arm64 early level initializer implementation
  cacheinfo: Add arch specific early level initializer
  tty: make tty_class a static const structure
  driver core: class: remove struct class_interface * from callbacks
  driver core: class: mark the struct class in struct class_interface constant
  driver core: class: make class_register() take a const *
  driver core: class: mark class_release() as taking a const *
  driver core: remove incorrect comment for device_create*
  MIPS: vpe-cmp: remove module owner pointer from struct class usage.
  ...
2023-04-27 11:53:57 -07:00
Greg Kroah-Hartman
6f14c02220 driver core: create class_is_registered()
Some classes (i.e. gpio), want to know if they have been registered or
not, and poke around in the class's internal structures to try to figure
this out.  Because this is not really a good idea, provide a function
for classes to call to try to figure this out.

Note, this is racy as the state of the class could change at any moment
in time after the call is made, but as usually a class only wants to
know if it has been registered yet or not, it should be fairly safe to
use, and is just as safe as the previous "poke at the class internals"
check was.

Move the gpiolib code to use this function as proof that it works
properly.

Cc: Bartosz Golaszewski <brgl@bgdev.pl>
Cc: Sebastian Reichel <sre@kernel.org>
Cc: Benjamin Tissoires <benjamin.tissoires@redhat.com>
Cc: linux-gpio@vger.kernel.org
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Reviewed-by: Rafael J. Wysocki <rafael@kernel.org>
Link: https://lore.kernel.org/r/20230331093318.82288-2-gregkh@linuxfoundation.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2023-03-31 17:44:54 +02:00
Greg Kroah-Hartman
75a2d4226b driver core: class: mark the struct class for sysfs callbacks as constant
struct class should never be modified in a sysfs callback as there is
nothing in the structure to modify, and frankly, the structure is almost
never used in a sysfs callback, so mark it as constant to allow struct
class to be moved to read-only memory.

While we are touching all class sysfs callbacks also mark the attribute
as constant as it can not be modified.  The bonding code still uses this
structure so it can not be removed from the function callbacks.

Cc: "David S. Miller" <davem@davemloft.net>
Cc: "Rafael J. Wysocki" <rafael@kernel.org>
Cc: Bartosz Golaszewski <brgl@bgdev.pl>
Cc: Eric Dumazet <edumazet@google.com>
Cc: Jakub Kicinski <kuba@kernel.org>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Johannes Berg <johannes@sipsolutions.net>
Cc: Linus Walleij <linus.walleij@linaro.org>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Miquel Raynal <miquel.raynal@bootlin.com>
Cc: Namjae Jeon <linkinjeon@kernel.org>
Cc: Paolo Abeni <pabeni@redhat.com>
Cc: Russ Weight <russell.h.weight@intel.com>
Cc: Sergey Senozhatsky <senozhatsky@chromium.org>
Cc: Steve French <sfrench@samba.org>
Cc: Vignesh Raghavendra <vigneshr@ti.com>
Cc: linux-cifs@vger.kernel.org
Cc: linux-gpio@vger.kernel.org
Cc: linux-mtd@lists.infradead.org
Cc: linux-rdma@vger.kernel.org
Cc: linux-s390@vger.kernel.org
Cc: linuxppc-dev@lists.ozlabs.org
Cc: netdev@vger.kernel.org
Reviewed-by: Luis Chamberlain <mcgrof@kernel.org>
Link: https://lore.kernel.org/r/20230325084537.3622280-1-gregkh@linuxfoundation.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2023-03-29 07:54:58 +02:00
Greg Kroah-Hartman
10a03c36b7 drivers: remove struct module * setting from struct class
There is no need to manually set the owner of a struct class, as the
registering function does it automatically, so remove all of the
explicit settings from various drivers that did so as it is unneeded.

This allows us to remove this pointer entirely from this structure going
forward.

Cc: "Rafael J. Wysocki" <rafael@kernel.org>
Link: https://lore.kernel.org/r/20230313181843.1207845-2-gregkh@linuxfoundation.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2023-03-17 15:16:27 +01:00
Andy Shevchenko
380c7ba392 gpiolib: Clean up headers
There is a few things done:
- include only the headers we are direct user of
- when pointer is in use, provide a forward declaration
- add missing headers
- group generic headers and subsystem headers
- sort each group alphabetically

Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
2023-03-06 12:33:02 +02:00
Arnd Bergmann
d74e316633 gpiolib: remove legacy gpio_export()
There are only a handful of users of gpio_export() and
related functions.

As these are just wrappers around the modern gpiod_export()
helper, remove the wrappers and open-code the gpio_to_desc
in all callers to shrink the legacy API.

Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
2023-03-06 12:33:01 +02:00