linux.git/drivers/gpio/gpiolib-cdev.c, branch v5.10

Merge tag 'gpio-v5.10-1' of git://git.kernel.org/pub/scm/linux/kernel/git/linusw/linux-gpio

2020-10-13T17:09:33+00:00

Pull GPIO updates from Linus Walleij:
"This time very little driver changes but lots of core changes.

We have some interesting cooperative work for ARM and Intel alike,
making the GPIO subsystem more and more suitable for industrial
systems and the like, in addition to the in-kernel users.

We touch driver core (device properties) and lib/* by adding one
simple string array free function, these are authored by Andy
Shevchenko who is a well known and recognized core helpers maintainers
so this should be fine.

We also see some Android GKI-related modularization in the MXC
drivers.

Core changes:

- The big core change is the updated (v2) userspace character device
API.

This corrects badly designed 64-bit alignment around the line
events. We also add the debounce request feature. This echoes the
often quotes passage from Frederick Brooks "The mythical man-month"
to always throw one away, which we have seen before in things such
as V4L2. So we put in a new one and deprecate and obsolete the old
one.

- All example tools in tools/gpio/* are migrated to the new API to
set a good example. The libgpiod userspace library has been
augmented to use this new API pretty much from day 1.

- Some misc API hardening by using strn* function calls has been
added as well.

- Use the simpler IDA interface for GPIO chip instance enumeration.

- Add device core function for counting string arrays in device
properties.

- Provide a generic library function kfree_strarray() that can be
used throughout the kernel.

Driver enhancements:

- The DesignWare dwapb-gpio driver has been enhanced and now uses the
IRQ handling in the gpiolib core.

- The mockup and aggregator drivers have seen some substantial code
clean-up and now use more of the core kernel inftrastructure.

- Misc cleanups using dev_err_probe().

- The MXC drivers (Freescale/NXP) can now be built modularized, which
makes modularized GKI Android kernels happy"

* tag 'gpio-v5.10-1' of git://git.kernel.org/pub/scm/linux/kernel/git/linusw/linux-gpio: (73 commits)
gpiolib: Update header block in gpiolib-cdev.h
gpiolib: cdev: switch from kstrdup() to kstrndup()
docs: gpio: add a new document to its index.rst
gpio: pca953x: Add support for the NXP PCAL9554B/C
tools: gpio: add debounce support to gpio-event-mon
tools: gpio: add multi-line monitoring to gpio-event-mon
tools: gpio: port gpio-event-mon to v2 uAPI
tools: gpio: port gpio-hammer to v2 uAPI
tools: gpio: rename nlines to num_lines
tools: gpio: port gpio-watch to v2 uAPI
tools: gpio: port lsgpio to v2 uAPI
gpio: uapi: document uAPI v1 as deprecated
gpiolib: cdev: support setting debounce
gpiolib: cdev: support GPIO_V2_LINE_SET_VALUES_IOCTL
gpiolib: cdev: support GPIO_V2_LINE_SET_CONFIG_IOCTL
gpiolib: cdev: support edge detection for uAPI v2
gpiolib: cdev: support GPIO_V2_GET_LINEINFO_IOCTL and GPIO_V2_GET_LINEINFO_WATCH_IOCTL
gpiolib: cdev: support GPIO_V2_GET_LINE_IOCTL and GPIO_V2_LINE_GET_VALUES_IOCTL
gpiolib: add build option for CDEV v1 ABI
gpiolib: make cdev a build option
...

gpiolib: cdev: switch from kstrdup() to kstrndup()

2020-10-08T20:57:16+00:00

Use kstrndup() to copy line labels from the userspace provided char
array, rather than ensuring the char array contains a null terminator
and using kstrdup().

Note that the length provided to kstrndup() still assumes that the char
array does contain a null terminator, so the maximum string length is one
less than the array.  This is consistent with the previous behaviour.

Suggested-by: Andy Shevchenko 
Signed-off-by: Kent Gibson 
Link: https://lore.kernel.org/r/20201005070246.20927-1-warthog618@gmail.com
Signed-off-by: Linus Walleij

gpiolib: Disable compat ->read() code in UML case

2020-10-07T09:42:03+00:00

It appears that UML (arch/um) has no compat.h header defined and hence
can't compile a recently provided piece of code in GPIO library.

Disable compat ->read() code in UML case to avoid compilation errors.

While at it, use pattern which is already being used in the kernel elsewhere.

Fixes: 5ad284ab3a01 ("gpiolib: Fix line event handling in syscall compatible mode")
Reported-by: Geert Uytterhoeven 
Signed-off-by: Andy Shevchenko 
Link: https://lore.kernel.org/r/20201005131044.87276-1-andriy.shevchenko@linux.intel.com
Signed-off-by: Linus Walleij

gpiolib: cdev: support setting debounce

2020-09-30T08:57:04+00:00

Add support for setting debounce on a line via the GPIO uAPI.
Where debounce is not supported by hardware, a software debounce is
provided.

The implementation of the software debouncer waits for the line to be
stable for the debounce period before determining if a level change,
and a corresponding edge event, has occurred.  This provides maximum
protection against glitches, but also introduces a debounce_period
latency to edge events.

The software debouncer is integrated with the edge detection as it
utilises the line interrupt, and integration is simpler than getting
the two to interwork.  Where software debounce AND edge detection is
required, the debouncer provides both.

Signed-off-by: Kent Gibson 
Signed-off-by: Bartosz Golaszewski

gpiolib: cdev: support GPIO_V2_LINE_SET_VALUES_IOCTL

2020-09-30T08:57:02+00:00

Add support for the GPIO_V2_LINE_SET_VALUES_IOCTL.

Signed-off-by: Kent Gibson 
Signed-off-by: Bartosz Golaszewski

gpiolib: cdev: support GPIO_V2_LINE_SET_CONFIG_IOCTL

2020-09-30T08:56:59+00:00

Add support for GPIO_V2_LINE_SET_CONFIG_IOCTL, the uAPI v2
line set config ioctl.

Signed-off-by: Kent Gibson 
Signed-off-by: Bartosz Golaszewski

gpiolib: cdev: support edge detection for uAPI v2

2020-09-30T08:56:56+00:00

Add support for edge detection to lines requested using
GPIO_V2_GET_LINE_IOCTL.

The edge_detector implementation is based on the v1 lineevent
implementation.  Unlike the v1 implementation, an overflow of the event
buffer results in discarding older events, rather than the most
recent, so the final event in a burst will correspond to the current
state of the line.

Signed-off-by: Kent Gibson 
Signed-off-by: Bartosz Golaszewski

gpiolib: cdev: support GPIO_V2_GET_LINEINFO_IOCTL and GPIO_V2_GET_LINEINFO_WATCH_IOCTL

2020-09-30T08:56:52+00:00

Add support for GPIO_V2_GET_LINEINFO_IOCTL and
GPIO_V2_GET_LINEINFO_WATCH_IOCTL.

The core of this change is the event kfifo switching to contain
struct gpioline_info_changed_v2, instead of v1 as v2 is richer.

The two uAPI versions are mostly independent - other than where they both
provide line info changes via reads on the chip fd.  As the info change
structs differ between v1 and v2, the infowatch implementation tracks which
version of the infowatch ioctl, either GPIO_GET_LINEINFO_WATCH_IOCTL or
GPIO_V2_GET_LINEINFO_WATCH_IOCTL, initiates the initial watch and returns
the corresponding info change struct to the read.  The version supported
on that fd locks to that version on the first watch request, so subsequent
watches from that process must use the same uAPI version.

Signed-off-by: Kent Gibson 
Signed-off-by: Bartosz Golaszewski

gpiolib: cdev: support GPIO_V2_GET_LINE_IOCTL and GPIO_V2_LINE_GET_VALUES_IOCTL

2020-09-30T08:56:49+00:00

Add support for requesting lines using the GPIO_V2_GET_LINE_IOCTL, and
returning their current values using GPIO_V2_LINE_GET_VALUES_IOCTL.

The struct linereq implementation is based on the v1 struct linehandle
implementation.

Signed-off-by: Kent Gibson 
Signed-off-by: Bartosz Golaszewski

gpiolib: cdev: replace strncpy() with strscpy()

2020-09-30T08:56:27+00:00

Replace usage of strncpy() with strscpy() to remove -Wstringop-truncation
warnings.

The structures being populated are zeroed, to prevent stack leakage as
they are returned to userspace, so strscpy() performs the equivalent
function without the warnings.

Reported-by: kernel test robot 
Signed-off-by: Kent Gibson 
Reviewed-by: Andy Shevchenko 
Signed-off-by: Bartosz Golaszewski