linux-sg2042/Documentation/ABI
Greg Kroah-Hartman c7c88e998a First round of IIO new device support, features and cleanups for the 4.10 cycle.
Fair number of outreachy related patches in here. Some of these may well
 have already been picked up by Greg but git will sort that out for us.
 
 Also some good staging cleanup work from other sources. Thanks Brian and Lars
 in particular for this.
 
 New device support
 * ACCES 104-quad-8
   - New driver for this 8 channel encoder input board. Lots of new ABI with
     this one.
 * AD7766
   - New driver supporting AD7766, AD7766-1, AD7766-2, AD7767, AD7767-1 and
     AD7767-2 24 bit ADCs.
 * dmard 10
   - New driver for this 3 axis accelerometer.
 * Honeywell ABP pressure sensors.
   - New driver covering 56 parts in this series (too many to list here!)
 * HTS221
   - New driver to support this relative humidiy and temperature device.
 * LMP91000
   - New driver for this potentiostat (form of chemical sensor). Nice example
     of use of the buffered consumer interfaces and the use of a consumer
     provided trigger.
 * MiraMEMS DA311
   - New driver for this 3 axis accelerometer.
 * MiraMEMS DA280
   - New driver for this 3 axis accelerometer. Follow up caught up with
   vendor prefixes for these.
 
 Staging graduations
 * isl29018 light sensor
   - Fixes and cleanups listed below (thanks for your hard work on this Brian!)
 * sca3000
   - Fixes and cleanups listed below.  This was one of the small set of drivers
   that went into staging when IIO was first added.  Turns out it had a few
   bugs and needed to be brought into the modern era!  Not clear if I am
   the only person who actually has one of these still wired to a board.
 
 New features (Core)
  - Add an iio_trigger_validate_own_device helper which relies on the device
    and trigger having the same parent.  Convenient to have this for some
    of the more complex trigger / device interactions. Was hand rolled in
    a few drivers already so good to bring it into the core.
  - Add an iio_read_channel_offset in kernel access helper (similar to
    the existing one for scale).
  - IIO_ATTR_{RO, WO, RW} and IIO_DEVICE_ATTR_{RO, WO, RW} macros.  These
    lead some rather contrived function naming, but there is no denying they
    do reduced boilerplate.  I'm going to resist their introduction in
    drivers 'unless' they form part of a larger set of cleanups.
  - Counter channel type and index type.
 
 New features (Drivers)
 * hdc100x
   - Triggered buffer support.
 * mcp4725
   - Device tree bindings and support.
   - Voltage reference selection.
 * ti-adc0832
   - Triggered buffer support.
 * ti-adc161s626
   - Add regulator support allowing _scale and _offset values to be established
   and exported.
 
 New features (Tools)
 * iio_generic_buffer
   - -A option to force enable all channels rather than faulting if some are
   already enabled (like -a does).  Followup patches tidied this support up.
 
 Cleanups (Core)
  - Use kmalloc_array in iio_scan_mask_set.
  - Take event_attrs field of iio_info structure constant
  - Staging todo list updates. Most of it was long done.
  - MAINTAINERS had a wrong directory listing.
 
 Cleanups (Drivers)
 * Missing i2c trivial devices entries.
 * ad5592r
   - Fix an endian type related sparse warnings.
 * ad7150
   - Constify the event attribute_group structures.
 * ad7152
   - Add some blank lines to improve readability.
   - Sampling frequency control via chan-info element rather than hand rolled
   attributes.
   - add a new lock to avoid use of mlock for non state change related locking.
 * ad7280
   - Constify atrribute_group structure (second patch covers the event ones)
 * ad7606 (Lars is driving most of the cleanup on this with some additions from
   Eva)
   - Fix improper setting of oversampling pins.  This has been broken a very
   long time in this staging driver, so not going to push this back to stable.
   - Implement oversampling configuration via the chan_info mask element.
   - Remove an unused int_vref_mv field.
   - Remove a reundant name field from ad7606_chip_info.
   - Remove default device configuration from platform_data in favour of
   whatever the power on defaults are.
   - Remove out of band error reporting in the kernel log as not providing
   much information.
   - Fix oversampling ratio by having 1 be the value for no oversampling.
   - Avoid allocating buffer for each data capture.
   - Factor out common code between periodic and one-shot capture.
   - Move set_drvdat into common code.
   - Let the common probe function return int rather than jumping through
   an ERR_PTR.
   - Pass struct device * into common remove to simplify code.
   - Always run trigger handler only once per event (no one can remember why
   it was being possibly done twice).
   - Move over to the GPIO descriptor API to shorten and clarify code.
   - Move the buffer code into the main file as it's not optional and is
   now rather short in this driver.
   - Fix the naming of the supply regulator.
   - Rework regulator handling to handle errors including deferred probing.
   - Tidy up a ptr_err or 0 return.
 * ad7746
   - Sampling frequency control via info_mask element rather than hand rolled
 * ad7758
   - Sampling frequency control via info_mask element rather than hand rolled
   attributes.
 * ad7816
   - Constify the event attribute_group structure.
 * adt7316
   - Constify the event attribute group structures.
 * ak8974
   - Cleanup some sparse warnings about endian types.
 * ak8975
   - Cleanup some sparse warnings about endian types.
 * bmi160
   - Spare endian warning cleanups.
 * isl29018 (towards staging graduation)
   - Remove unusedvariables and defines.
   - Improve consistency of error handling.
   - Signed / unsigned comparison fixes.
   - Use the IIO_DEVICE_ATTR_{RO, RW} macros
   - Fix a race in in_illuminance_scale_available_show.
   - Cleanup exit points of _read_raw
   - Sanity check if in suspended state during a write_raw call as was already
     done for read_raw.
   - Document device tree bidnings.
   - Document infrared supression controls.
   - Add some newlines to improve readability and drop one that shouldn't be
     there.
   - Fix a poorly named functions name.
   - Fix multiline coment syntax.
   - Tidy up a pair or return statements by unifying them.
   - Rename description in Kconfig for consistency with similar drivers.
 * lidar
   - cleanup power management by dropping unnecessary call.
 * ltr501
   - Use the claim_direct_mode helpers. Fix a race condition along the way.
 * max1027
   - Fix a dubious x | !y sparse warning.
   - Use the new iio_trigger_validate_own_device helper.
 * max440000
   - Clean up some sparse warnings about endian types.
 * mcp4725
   - Use the regulator framework to establish the reference voltage rather than
     getting it from platform data.
   - Tidy up a comment typo.
   - Fix a wrong PTR_ERR query (wrong regulator).
 * mma7660
   - Take a mma7660_nscale static.
 * mma8452
   - Use the new iio_trigger_validate_own_device helper.
   - Use claim_direct_mode helpers - fix a race condition along the way.
 * mpl3115
   - Use claim_direct_mode helpers - fix a race condition along the way.
 * ms65611
   - Tidy up regulator error handling and clean out a static warning in the mix.
 * sca3000
   - Avoid a potential unitialized variable if a hardware read returns a value
   that isn't actually supported (mostly warning supression).
   - Fix a use before setting of the indio_dev->buffer pointer. Broken for
   a very long time so not going to rush this into stable.
   - Merge buffer file with core file.  We used to always split these.
   Sometimes it's just not worth the hassle. In this case the device's main
   feature is it's hardware fifos so unlikely anyone would want to run it
   without.
   - Drop the sca3000_register_ring_funcs function as it's a pointless wrapper
   once we have only one file.
   - Fix cleaning of flag + setting of size of scan. Without this you can't
   start the buffer twice and expect sensible (or any) results.  Again,
   broken for a long time so not heading for stable.
   - Drop the custom watershed setting ABI - for now we'll just support one
   value.
   - Move to a hybrid hard / soft buffer design (how we've been doing it
   for similar devices for a while now!)
   - Cleanup some unusued variables.
   - Use a fake channel to support core handling of freefall event registration.
   - Cleanup the register defines.
   - Fix an off by one error in axis due to IIO_NO_MOD taking up the 0 value.
   Been broken since first admission of IIO to the staging tree.
   - Add readback of the 3db low pass filter frequency and later writing
     allowing droppign of custom measurement mode attributes as they can
     be represented by the filter choices that is their main characteristic.
   - Drop non standard revision attr and replace with dev_info on probe.
   - Avoid a race in probe.
   - Various formatting fixes.
   - Kernel-docify docs that were very nearly in the write format.
 * tsl2583
   - Constify attribute_group structure.
 * zpa2326
   - Drop a redundant DEBUG ifdef.
 
 Cleanups (Tools)
 * iio_generic_buffer
   - Fix the ? arguement. Previously it sort of worked as you got the help
     message as a result of it not recognising the arguement.
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Merge tag 'iio-for-4.10a' of git://git.kernel.org/pub/scm/linux/kernel/git/jic23/iio into staging-next

Jonathan writes:

First round of IIO new device support, features and cleanups for the 4.10 cycle.

Fair number of outreachy related patches in here. Some of these may well
have already been picked up by Greg but git will sort that out for us.

Also some good staging cleanup work from other sources. Thanks Brian and Lars
in particular for this.

New device support
* ACCES 104-quad-8
  - New driver for this 8 channel encoder input board. Lots of new ABI with
    this one.
* AD7766
  - New driver supporting AD7766, AD7766-1, AD7766-2, AD7767, AD7767-1 and
    AD7767-2 24 bit ADCs.
* dmard 10
  - New driver for this 3 axis accelerometer.
* Honeywell ABP pressure sensors.
  - New driver covering 56 parts in this series (too many to list here!)
* HTS221
  - New driver to support this relative humidiy and temperature device.
* LMP91000
  - New driver for this potentiostat (form of chemical sensor). Nice example
    of use of the buffered consumer interfaces and the use of a consumer
    provided trigger.
* MiraMEMS DA311
  - New driver for this 3 axis accelerometer.
* MiraMEMS DA280
  - New driver for this 3 axis accelerometer. Follow up caught up with
  vendor prefixes for these.

Staging graduations
* isl29018 light sensor
  - Fixes and cleanups listed below (thanks for your hard work on this Brian!)
* sca3000
  - Fixes and cleanups listed below.  This was one of the small set of drivers
  that went into staging when IIO was first added.  Turns out it had a few
  bugs and needed to be brought into the modern era!  Not clear if I am
  the only person who actually has one of these still wired to a board.

New features (Core)
 - Add an iio_trigger_validate_own_device helper which relies on the device
   and trigger having the same parent.  Convenient to have this for some
   of the more complex trigger / device interactions. Was hand rolled in
   a few drivers already so good to bring it into the core.
 - Add an iio_read_channel_offset in kernel access helper (similar to
   the existing one for scale).
 - IIO_ATTR_{RO, WO, RW} and IIO_DEVICE_ATTR_{RO, WO, RW} macros.  These
   lead some rather contrived function naming, but there is no denying they
   do reduced boilerplate.  I'm going to resist their introduction in
   drivers 'unless' they form part of a larger set of cleanups.
 - Counter channel type and index type.

New features (Drivers)
* hdc100x
  - Triggered buffer support.
* mcp4725
  - Device tree bindings and support.
  - Voltage reference selection.
* ti-adc0832
  - Triggered buffer support.
* ti-adc161s626
  - Add regulator support allowing _scale and _offset values to be established
  and exported.

New features (Tools)
* iio_generic_buffer
  - -A option to force enable all channels rather than faulting if some are
  already enabled (like -a does).  Followup patches tidied this support up.

Cleanups (Core)
 - Use kmalloc_array in iio_scan_mask_set.
 - Take event_attrs field of iio_info structure constant
 - Staging todo list updates. Most of it was long done.
 - MAINTAINERS had a wrong directory listing.

Cleanups (Drivers)
* Missing i2c trivial devices entries.
* ad5592r
  - Fix an endian type related sparse warnings.
* ad7150
  - Constify the event attribute_group structures.
* ad7152
  - Add some blank lines to improve readability.
  - Sampling frequency control via chan-info element rather than hand rolled
  attributes.
  - add a new lock to avoid use of mlock for non state change related locking.
* ad7280
  - Constify atrribute_group structure (second patch covers the event ones)
* ad7606 (Lars is driving most of the cleanup on this with some additions from
  Eva)
  - Fix improper setting of oversampling pins.  This has been broken a very
  long time in this staging driver, so not going to push this back to stable.
  - Implement oversampling configuration via the chan_info mask element.
  - Remove an unused int_vref_mv field.
  - Remove a reundant name field from ad7606_chip_info.
  - Remove default device configuration from platform_data in favour of
  whatever the power on defaults are.
  - Remove out of band error reporting in the kernel log as not providing
  much information.
  - Fix oversampling ratio by having 1 be the value for no oversampling.
  - Avoid allocating buffer for each data capture.
  - Factor out common code between periodic and one-shot capture.
  - Move set_drvdat into common code.
  - Let the common probe function return int rather than jumping through
  an ERR_PTR.
  - Pass struct device * into common remove to simplify code.
  - Always run trigger handler only once per event (no one can remember why
  it was being possibly done twice).
  - Move over to the GPIO descriptor API to shorten and clarify code.
  - Move the buffer code into the main file as it's not optional and is
  now rather short in this driver.
  - Fix the naming of the supply regulator.
  - Rework regulator handling to handle errors including deferred probing.
  - Tidy up a ptr_err or 0 return.
* ad7746
  - Sampling frequency control via info_mask element rather than hand rolled
* ad7758
  - Sampling frequency control via info_mask element rather than hand rolled
  attributes.
* ad7816
  - Constify the event attribute_group structure.
* adt7316
  - Constify the event attribute group structures.
* ak8974
  - Cleanup some sparse warnings about endian types.
* ak8975
  - Cleanup some sparse warnings about endian types.
* bmi160
  - Spare endian warning cleanups.
* isl29018 (towards staging graduation)
  - Remove unusedvariables and defines.
  - Improve consistency of error handling.
  - Signed / unsigned comparison fixes.
  - Use the IIO_DEVICE_ATTR_{RO, RW} macros
  - Fix a race in in_illuminance_scale_available_show.
  - Cleanup exit points of _read_raw
  - Sanity check if in suspended state during a write_raw call as was already
    done for read_raw.
  - Document device tree bidnings.
  - Document infrared supression controls.
  - Add some newlines to improve readability and drop one that shouldn't be
    there.
  - Fix a poorly named functions name.
  - Fix multiline coment syntax.
  - Tidy up a pair or return statements by unifying them.
  - Rename description in Kconfig for consistency with similar drivers.
* lidar
  - cleanup power management by dropping unnecessary call.
* ltr501
  - Use the claim_direct_mode helpers. Fix a race condition along the way.
* max1027
  - Fix a dubious x | !y sparse warning.
  - Use the new iio_trigger_validate_own_device helper.
* max440000
  - Clean up some sparse warnings about endian types.
* mcp4725
  - Use the regulator framework to establish the reference voltage rather than
    getting it from platform data.
  - Tidy up a comment typo.
  - Fix a wrong PTR_ERR query (wrong regulator).
* mma7660
  - Take a mma7660_nscale static.
* mma8452
  - Use the new iio_trigger_validate_own_device helper.
  - Use claim_direct_mode helpers - fix a race condition along the way.
* mpl3115
  - Use claim_direct_mode helpers - fix a race condition along the way.
* ms65611
  - Tidy up regulator error handling and clean out a static warning in the mix.
* sca3000
  - Avoid a potential unitialized variable if a hardware read returns a value
  that isn't actually supported (mostly warning supression).
  - Fix a use before setting of the indio_dev->buffer pointer. Broken for
  a very long time so not going to rush this into stable.
  - Merge buffer file with core file.  We used to always split these.
  Sometimes it's just not worth the hassle. In this case the device's main
  feature is it's hardware fifos so unlikely anyone would want to run it
  without.
  - Drop the sca3000_register_ring_funcs function as it's a pointless wrapper
  once we have only one file.
  - Fix cleaning of flag + setting of size of scan. Without this you can't
  start the buffer twice and expect sensible (or any) results.  Again,
  broken for a long time so not heading for stable.
  - Drop the custom watershed setting ABI - for now we'll just support one
  value.
  - Move to a hybrid hard / soft buffer design (how we've been doing it
  for similar devices for a while now!)
  - Cleanup some unusued variables.
  - Use a fake channel to support core handling of freefall event registration.
  - Cleanup the register defines.
  - Fix an off by one error in axis due to IIO_NO_MOD taking up the 0 value.
  Been broken since first admission of IIO to the staging tree.
  - Add readback of the 3db low pass filter frequency and later writing
    allowing droppign of custom measurement mode attributes as they can
    be represented by the filter choices that is their main characteristic.
  - Drop non standard revision attr and replace with dev_info on probe.
  - Avoid a race in probe.
  - Various formatting fixes.
  - Kernel-docify docs that were very nearly in the write format.
* tsl2583
  - Constify attribute_group structure.
* zpa2326
  - Drop a redundant DEBUG ifdef.

Cleanups (Tools)
* iio_generic_buffer
  - Fix the ? arguement. Previously it sort of worked as you got the help
    message as a result of it not recognising the arguement.
2016-10-24 11:34:22 +02:00
..
obsolete Documentation: fix common spelling mistakes 2016-04-28 07:51:59 -06:00
removed rfkill: Remove obsolete "claim" sysfs interface 2016-02-24 09:04:24 +01:00
stable documentation: drivers/core/of: fix name of of_node symlink 2016-08-31 15:14:44 +02:00
testing First round of IIO new device support, features and cleanups for the 4.10 cycle. 2016-10-24 11:34:22 +02:00
README Documentation/ABI: document the non-ABI status of Kconfig and symbols 2013-11-13 12:09:32 +09:00

README

This 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:	Kernel version this feature first showed up in.
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.


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/stable_api_nonsense.txt.