linux/Documentation/ABI
Greg Kroah-Hartman 9991bbc6d5 IIO: New device support, features and cleanup for the 6.20/7.0 cycle.
Slightly messier than normal unfortunately due to some conflicts
 and build config bugs related to I3C drivers.
 
 One last minute Kconfig fix right at the top after a linux-next report.
 I've simplified the Kconfig and made it match other instances in the kernel
 so that should be safe enough despite short soak time in front of build bots.
 
 Merge of an immutable branch from I3C to get some stubs that were missing
 and caused build issues with dual I2C / I3C drivers. This also brought in a
 drop of some deprecated interfaces so there is also one patch to update a
 new driver to not use those.
 
 We are having another go at using cleanup.h magic with the IIO mode claim
 functions after backing out last try at this. This time we have wrappers
 around the new ACQUIRE() and ACQUIRE_ERR() macros.
 Having been burnt once, we will be taking it a bit more slowly this time
 wrt to wide adoption of these! Thanks in particular to Kurt for taking
 on this core IIO work.
 
 New Device Support
 ==================
 
 adi,ad18113
 - New driver to support the AD18113 amplifier - an interesting device due
   to the external bypass paths where we need to describe what gain those
   paths have in DT. Longer term it will be interesting to see if this
   simplistic description is enough for real deployments.
 adi,ad4062
 - New driver for the AD4060 and AD4052 SAR ADCs including trigger, event
   and GPIO controller support.  Follow up patch replaced use of some
   deprecated I3C interfaces prior to the I3C immutable branch merge as
   that includes dropping them.
 adi,ad4134
 - New driver for the AD4134 24bit 4 channel simultaneous sampling ADC.
 adi,ad7768-1,
 - Add support for the ADAQ767-1, ADAQ7768-1 and ADAQ7769-1 ADCs after some
   rework to enable the driver to support multiple device types.
 adi,ad9467
 - Add support for the similar ad9211 ADC to this existing driver.
 - Make the selection of 2s comp mode explicit for normal operation and
   switch to offset binary when entering calibration mode.
 honeywell,abp2
 - New driver to support this huge family (100+) of board mount pressure and
   temperature sensors.
 maxim,max22007
 - New drier for this 4 channel DAC.
 memsic,mmc5633
 - New driver for this I2C/I3C magnetometer. Follow on patches fixed up
   issues related to single driver supporting both bus types.
 microchip,mcp747feb02
 - New driver for the Microchip MCP47F(E/V)B(0/1/2)1,
   MCP47F(E/V)B(0/1/2)2, MCP47F(E/V)B(0/1/2)4 and MCP47F(E/V)B(0/1/2)8
   buffered voltage output DACs.
 nxp,sar-adc
 - New driver support ADCs found on s32g2 and s32g3 platforms.
 ti,ads1018
 - New drier for the ADS1018 and ADS1118 SPI ADCs.
 ti,ads131m02
 - New driver supporting ADS131M(02/03/04/06/08)24-bit simultaneous sampling
   ADCs.
 
 Features
 ========
 
 iio-core
 - New IIO_DEV_ACQUIRE_DIRECT_MODE() / IIO_DEV_ACQUIRE_FAILED() +
   equivalents for the much rarer case where the mode needs pinning
   whether or not it is in direct mode.  These use the ACQUIRE()
   / ACQUIRE_ERR() infrastructure underneath to provide both simple
   checks on whether we got the requested mode and to provide scope
   based release. Applied in a few initial drivers.
 adi,ad9467
 - Support calibbias control
 adi,adf4377
 - Add support to act as a clock provider.
 adi,adxl380
 - Support low power 1KHz sampling frequency mode. Required rework of
   how events and filters were configured, plus applying of constraints
   when in this mode.
 rf-digital,rfd77402
 - Add interrupt support as alternative to polling for completion.
 st,lsm6dsx
 - Tap event detection (after considerable driver rework)
 
 Cleanup and Minor Fixes
 =======================
 
 More minor cleanup such as typos, white space etc not called out except
 where they were applied to a lot of drivers.
 
 Various drivers.
 - Use of dev_err_probe() to cleanup error handling.
 - Introduce local struct device and struct device_node variables to
   reduce duplication of getting them from containing structs.
 - Ensure uses of iio_trigger_generic_data_rdy_poll() set IRQF_NO_THREAD
   as that function calls non threaded child interrupt handlers.
 - Replace IRQF_ONESHOT in not thread interrupt handlers with
   IRQF_NO_THREAD to ensure they run as intended. Drop one unnecessary case.
 iio-sw-device/trigger.
 - Constify configs_group_operations structures.
 iio-buffer-dma / buffer-dma-engine
 - Use lockdep_assert_held() to replace WARN_ON() to check lock is
   correctly held.
 - Make use of cleanup.h magic to simplify various code paths.
 - Make iio_dma_buffer_init() return void rather than always success.
 
 adi,ad7766
 - Replace custom interrupt handler with iio_trigger_generic_data_rdy_poll()
 adi,ad9832
 - Drop legacy platform_data support.
 adi,ade9000
 - Add a maintainer entry.
 adi,adt7316
 - Move to EXPORT_GPL_SIMPLE_DEV_PM_OPS() and pm_sleep_ptr() so the compiler
   can cleanly drop unused pm structures and callbacks.
 adi,adxl345
 - Relax build constraint vs the driver that is in input so both may be
   built as modules and selection made at runtime.
 adi,adxl380
 - Make sure we don't read tail entries in the hardware fifo if a partial
   new scan has been written.
 - Move to a single larger regmap_noinc_read() to read the hardware fifo.
 aspeed,ast2600
 - Add missing interrupts property to DT binding.
 bosch,bmi270_i2c
 - Add missing MODULE_DEVICE_TABLE() macros so auto probing of modules can
   work.
 bosch,smi330
 - Drop duplicate assignment of IIO_TYPE in smi330_read_avail()
 - Use new common field_get() and field_prep() helpers to replace local
   version.
 honeywell,mprls0025pa
   Fixes delayed to merge window as late in cycle and we didn't want to delay
   the rest of the series.
 - Allow Kconfig selection of specific bus sub-drivers rather than tying that
   to the buses themselves being supported.
 - Zero spi_transfer structure to avoid chance of unintentionally set fields
   effecting transfer.
 - Fix a potential timing violation wrt to the chip select to first clock
   edge timing.
 - As recent driver, take risk inherent in dropping interrupt direction from
   driver as that should be set by firmware.
 - Fix wrong reported number of data bits for channel.
 - Fix a pressure channel calculation bug.
 - Rework to allow embedding the tx buffer in the iio_priv() structure rather
   than requiring separate allocation.
 - Move the buffer clearing to the shared core bringing it into affect for
   SPI as well as I2C.
 - Stricter checks for status byte.
 - Greatly simplify the measurement sequence.
 - Add a copyright entry to reflect Petre's continued work on this driver.
 intersil,isl29018
 - Switch from spritnf to sysfs_emit_at() to make it clear overflow can't
   occur.
 invensense,icm42600
 - Allow sysfs access to temperature when buffered capture in use as it
   does not impact other sensor data paths.
 invensense,itg3200
 - Check unused return value in read_raw() callback.
 men,z188
 - Drop now duplicated module alias.
 rf-digital,rfd77402
 - Add DT binding doc and explicit of_device_id table.
 - Poll for timeout with times as on datasheet, then replace opencoded
   version with read_poll_timeout().
 sensiron,scd4x
 - Add missing timestamp channel. The code to push it to the buffer was there
   but there was no way to turn it on.
 vti,sca3000
 - Fix resource leak if iio_device_register() fails.
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Merge tag 'iio-for-7.0a' of ssh://gitolite.kernel.org/pub/scm/linux/kernel/git/jic23/iio into char-misc-next

Jonathan writes:

IIO: New device support, features and cleanup for the 6.20/7.0 cycle.

Slightly messier than normal unfortunately due to some conflicts
and build config bugs related to I3C drivers.

One last minute Kconfig fix right at the top after a linux-next report.
I've simplified the Kconfig and made it match other instances in the kernel
so that should be safe enough despite short soak time in front of build bots.

Merge of an immutable branch from I3C to get some stubs that were missing
and caused build issues with dual I2C / I3C drivers. This also brought in a
drop of some deprecated interfaces so there is also one patch to update a
new driver to not use those.

We are having another go at using cleanup.h magic with the IIO mode claim
functions after backing out last try at this. This time we have wrappers
around the new ACQUIRE() and ACQUIRE_ERR() macros.
Having been burnt once, we will be taking it a bit more slowly this time
wrt to wide adoption of these! Thanks in particular to Kurt for taking
on this core IIO work.

New Device Support
==================

adi,ad18113
- New driver to support the AD18113 amplifier - an interesting device due
  to the external bypass paths where we need to describe what gain those
  paths have in DT. Longer term it will be interesting to see if this
  simplistic description is enough for real deployments.
adi,ad4062
- New driver for the AD4060 and AD4052 SAR ADCs including trigger, event
  and GPIO controller support.  Follow up patch replaced use of some
  deprecated I3C interfaces prior to the I3C immutable branch merge as
  that includes dropping them.
adi,ad4134
- New driver for the AD4134 24bit 4 channel simultaneous sampling ADC.
adi,ad7768-1,
- Add support for the ADAQ767-1, ADAQ7768-1 and ADAQ7769-1 ADCs after some
  rework to enable the driver to support multiple device types.
adi,ad9467
- Add support for the similar ad9211 ADC to this existing driver.
- Make the selection of 2s comp mode explicit for normal operation and
  switch to offset binary when entering calibration mode.
honeywell,abp2
- New driver to support this huge family (100+) of board mount pressure and
  temperature sensors.
maxim,max22007
- New drier for this 4 channel DAC.
memsic,mmc5633
- New driver for this I2C/I3C magnetometer. Follow on patches fixed up
  issues related to single driver supporting both bus types.
microchip,mcp747feb02
- New driver for the Microchip MCP47F(E/V)B(0/1/2)1,
  MCP47F(E/V)B(0/1/2)2, MCP47F(E/V)B(0/1/2)4 and MCP47F(E/V)B(0/1/2)8
  buffered voltage output DACs.
nxp,sar-adc
- New driver support ADCs found on s32g2 and s32g3 platforms.
ti,ads1018
- New drier for the ADS1018 and ADS1118 SPI ADCs.
ti,ads131m02
- New driver supporting ADS131M(02/03/04/06/08)24-bit simultaneous sampling
  ADCs.

Features
========

iio-core
- New IIO_DEV_ACQUIRE_DIRECT_MODE() / IIO_DEV_ACQUIRE_FAILED() +
  equivalents for the much rarer case where the mode needs pinning
  whether or not it is in direct mode.  These use the ACQUIRE()
  / ACQUIRE_ERR() infrastructure underneath to provide both simple
  checks on whether we got the requested mode and to provide scope
  based release. Applied in a few initial drivers.
adi,ad9467
- Support calibbias control
adi,adf4377
- Add support to act as a clock provider.
adi,adxl380
- Support low power 1KHz sampling frequency mode. Required rework of
  how events and filters were configured, plus applying of constraints
  when in this mode.
rf-digital,rfd77402
- Add interrupt support as alternative to polling for completion.
st,lsm6dsx
- Tap event detection (after considerable driver rework)

Cleanup and Minor Fixes
=======================

More minor cleanup such as typos, white space etc not called out except
where they were applied to a lot of drivers.

Various drivers.
- Use of dev_err_probe() to cleanup error handling.
- Introduce local struct device and struct device_node variables to
  reduce duplication of getting them from containing structs.
- Ensure uses of iio_trigger_generic_data_rdy_poll() set IRQF_NO_THREAD
  as that function calls non threaded child interrupt handlers.
- Replace IRQF_ONESHOT in not thread interrupt handlers with
  IRQF_NO_THREAD to ensure they run as intended. Drop one unnecessary case.
iio-sw-device/trigger.
- Constify configs_group_operations structures.
iio-buffer-dma / buffer-dma-engine
- Use lockdep_assert_held() to replace WARN_ON() to check lock is
  correctly held.
- Make use of cleanup.h magic to simplify various code paths.
- Make iio_dma_buffer_init() return void rather than always success.

adi,ad7766
- Replace custom interrupt handler with iio_trigger_generic_data_rdy_poll()
adi,ad9832
- Drop legacy platform_data support.
adi,ade9000
- Add a maintainer entry.
adi,adt7316
- Move to EXPORT_GPL_SIMPLE_DEV_PM_OPS() and pm_sleep_ptr() so the compiler
  can cleanly drop unused pm structures and callbacks.
adi,adxl345
- Relax build constraint vs the driver that is in input so both may be
  built as modules and selection made at runtime.
adi,adxl380
- Make sure we don't read tail entries in the hardware fifo if a partial
  new scan has been written.
- Move to a single larger regmap_noinc_read() to read the hardware fifo.
aspeed,ast2600
- Add missing interrupts property to DT binding.
bosch,bmi270_i2c
- Add missing MODULE_DEVICE_TABLE() macros so auto probing of modules can
  work.
bosch,smi330
- Drop duplicate assignment of IIO_TYPE in smi330_read_avail()
- Use new common field_get() and field_prep() helpers to replace local
  version.
honeywell,mprls0025pa
  Fixes delayed to merge window as late in cycle and we didn't want to delay
  the rest of the series.
- Allow Kconfig selection of specific bus sub-drivers rather than tying that
  to the buses themselves being supported.
- Zero spi_transfer structure to avoid chance of unintentionally set fields
  effecting transfer.
- Fix a potential timing violation wrt to the chip select to first clock
  edge timing.
- As recent driver, take risk inherent in dropping interrupt direction from
  driver as that should be set by firmware.
- Fix wrong reported number of data bits for channel.
- Fix a pressure channel calculation bug.
- Rework to allow embedding the tx buffer in the iio_priv() structure rather
  than requiring separate allocation.
- Move the buffer clearing to the shared core bringing it into affect for
  SPI as well as I2C.
- Stricter checks for status byte.
- Greatly simplify the measurement sequence.
- Add a copyright entry to reflect Petre's continued work on this driver.
intersil,isl29018
- Switch from spritnf to sysfs_emit_at() to make it clear overflow can't
  occur.
invensense,icm42600
- Allow sysfs access to temperature when buffered capture in use as it
  does not impact other sensor data paths.
invensense,itg3200
- Check unused return value in read_raw() callback.
men,z188
- Drop now duplicated module alias.
rf-digital,rfd77402
- Add DT binding doc and explicit of_device_id table.
- Poll for timeout with times as on datasheet, then replace opencoded
  version with read_poll_timeout().
sensiron,scd4x
- Add missing timestamp channel. The code to push it to the buffer was there
  but there was no way to turn it on.
vti,sca3000
- Fix resource leak if iio_device_register() fails.

* tag 'iio-for-7.0a' of ssh://gitolite.kernel.org/pub/scm/linux/kernel/git/jic23/iio: (144 commits)
  iio: magn: mmc5633: Fix Kconfig for combination of I3C as module and driver builtin
  iio: sca3000: Fix a resource leak in sca3000_probe()
  iio: proximity: rfd77402: Add interrupt handling support
  iio: proximity: rfd77402: Document device private data structure
  iio: proximity: rfd77402: Use devm-managed mutex initialization
  iio: proximity: rfd77402: Use kernel helper for result polling
  iio: proximity: rfd77402: Align polling timeout with datasheet
  iio: cros_ec: Allow enabling/disabling calibration mode
  iio: frequency: ad9523: correct kernel-doc bad line warning
  iio: buffer: buffer_impl.h: fix kernel-doc warnings
  iio: gyro: itg3200: Fix unchecked return value in read_raw
  MAINTAINERS: add entry for ADE9000 driver
  iio: accel: sca3000: remove unused last_timestamp field
  iio: accel: adxl372: remove unused int2_bitmask field
  iio: adc: ad7766: Use iio_trigger_generic_data_rdy_poll()
  iio: magnetometer: Remove IRQF_ONESHOT
  iio: Replace IRQF_ONESHOT with IRQF_NO_THREAD
  iio: Use IRQF_NO_THREAD
  iio: dac: Add MAX22007 DAC driver support
  dt-bindings: iio: dac: Add max22007
  ...
2026-02-02 17:08:30 +01:00
..
obsolete Documentation/ABI: mark old kexec sysfs deprecated 2025-11-27 14:24:43 -08:00
removed docs: Fix references to IBM CAPI (cxl) removal version 2025-04-02 23:09:52 +11:00
stable speakup: Clarify bleep_time unit is milliseconds 2026-01-27 15:54:31 +01:00
testing IIO: New device support, features and cleanup for the 6.20/7.0 cycle. 2026-02-02 17:08:30 +01:00
README docs: ABI: make the KernelVersion field optional 2025-07-01 13:18:04 -06:00

This part of the documentation inside Documentation/ABI directory
attempts to document the ABI between the Linux kernel and
userspace, and the relative stability of these interfaces.  Due to the
everchanging nature of Linux, and the differing maturity levels, these
interfaces should be used by userspace programs in different ways.

We have four different levels of ABI stability, as shown by the four
different subdirectories in this location.  Interfaces may change levels
of stability according to the rules described below.

The different levels of stability are:

  stable/
	This directory documents the interfaces that the developer has
	defined to be stable.  Userspace programs are free to use these
	interfaces with no restrictions, and backward compatibility for
	them will be guaranteed for at least 2 years.  Most interfaces
	(like syscalls) are expected to never change and always be
	available.

  testing/
	This directory documents interfaces that are felt to be stable,
	as the main development of this interface has been completed.
	The interface can be changed to add new features, but the
	current interface will not break by doing this, unless grave
	errors or security problems are found in them.  Userspace
	programs can start to rely on these interfaces, but they must be
	aware of changes that can occur before these interfaces move to
	be marked stable.  Programs that use these interfaces are
	strongly encouraged to add their name to the description of
	these interfaces, so that the kernel developers can easily
	notify them if any changes occur (see the description of the
	layout of the files below for details on how to do this.)

  obsolete/
	This directory documents interfaces that are still remaining in
	the kernel, but are marked to be removed at some later point in
	time.  The description of the interface will document the reason
	why it is obsolete and when it can be expected to be removed.

  removed/
	This directory contains a list of the old interfaces that have
	been removed from the kernel.

Every file in these directories will contain the following information:

What:		Short description of the interface
Date:		Date created
KernelVersion:	(Optional) Kernel version this feature first showed up in.
		Note: git history often provides more accurate version
		info, so this field may be omitted.
Contact:	Primary contact for this interface (may be a mailing list)
Description:	Long description of the interface and how to use it.
Users:		All users of this interface who wish to be notified when
		it changes.  This is very important for interfaces in
		the "testing" stage, so that kernel developers can work
		with userspace developers to ensure that things do not
		break in ways that are unacceptable.  It is also
		important to get feedback for these interfaces to make
		sure they are working in a proper way and do not need to
		be changed further.


Note:
   The fields should be use a simple notation, compatible with ReST markup.
   Also, the file **should not** have a top-level index, like::

	===
	foo
	===

How things move between levels:

Interfaces in stable may move to obsolete, as long as the proper
notification is given.

Interfaces may be removed from obsolete and the kernel as long as the
documented amount of time has gone by.

Interfaces in the testing state can move to the stable state when the
developers feel they are finished.  They cannot be removed from the
kernel tree without going through the obsolete state first.

It's up to the developer to place their interfaces in the category they
wish for it to start out in.


Notable bits of non-ABI, which should not under any circumstances be considered
stable:

- Kconfig.  Userspace should not rely on the presence or absence of any
  particular Kconfig symbol, in /proc/config.gz, in the copy of .config
  commonly installed to /boot, or in any invocation of the kernel build
  process.

- Kernel-internal symbols.  Do not rely on the presence, absence, location, or
  type of any kernel symbol, either in System.map files or the kernel binary
  itself.  See Documentation/process/stable-api-nonsense.rst.