OpenCloudOS-Kernel/Documentation/ABI
Greg Kroah-Hartman ec3c13e4ac Third set of IIO new device support, features and cleanups for the 4.6 cycle.
Good to see several new contributors in this set - and more generally a
 number of new 'faces' over this whole cycle.
 
 Staging movements
 * hmc5843
   - out of staging.
 * periodic RTC trigger
   - driver dropped.  This is an ancient driver (brings back some memories ;)
   that was always somewhat of a bodge. Originally there was a driver that
   never went into mainline that supported large numbers of periodict timers
   on the PXA270 via this route. Discussions to have a generic periodic
   timer subsystem never went anywhere.  At the time RTC periodic
   interrupts were real - now they are emulated using high resolution
   timers so with the HRT driver this has become pointless.
 
 New device support
 * mpu6050 driver
   - Add support for the mpu6500.
 * TI tpl0102 potentiometer
   - new driver.
 * Vybrid SoC DAC
   - new driver.  The ADC on this SoC has been supported for a while, this
     adds a separate driver for the DAC.
 
 New Features
 * hmc5844
   - Attributes to configure the bias current (typically part of a self test)
     This could be done before via a somewhat obscure custom interface.
     This at least makes it easy to tell what is going on.
   - Document all custom attributes.
 * mpu6050
   - Add support for calibration offset control and readback.
 * ms5611
   - power regulator support.  This is always one that gets added the
     first time someone has a board that needs it.  Here it was needed,
     hence it was added.
 
 Cleanups / minor fixes
 * tree wide
   - clean up all the myriad different return values in response to a
     failure of i2c_check_functionality.  After discussions everyone seemed
     happy wiht -EOPNOTSUPP which seems to describe the situation well.
     I encouraged a tree wide cleanup to set a good example in future for
     this.
 * core
   - Typos in the iio_event_spec documentation in iio.h
 * afe4403
   - select REGMAP_SPI to avoid dependency issues
   - mark suspend/resume as __maybe_unused to avoid warnings
 * afe4404
   - mark suspend/resume as __maybe_unused to avoid warnings
 * atlas-ph-sensor
   - switch the regmap cache type from linear to rbtree to gain reading of
     registers on initial startup.  It's not immediately obvious, but
     regmap flat is meant for high performances cases so doesn't read these
     registers.
   - use regmap_bulk_read in one case where it was using
     i2c_smbus_read_i2c_block_data directly (unlike everything else that was
     through regmap).
 * ina2xx
   - stype cleanups (lots of them!)
 * isl29018
   - Get the struct device back from regmap rather than storing another
     copy of it in the private data.  This cleanup makes sense in a number
     of other drivers so patches may well follow.
 * mpu6050
   - style cleanups (lots of them!)
   - improved return value handling
   - use usleep_range to avoid the usual issues with very short msleeps.
   - add some missing documentation.
 * ms5611
   - use the probed device name for the device rather than the driver name.
   - select IIO_BUFFER to avoid dependency issues
 * palmas
   - drop IRQF_EARLY_RESUME as no longer needed after genirq changes.
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Merge tag 'iio-for-4.6c' of git://git.kernel.org/pub/scm/linux/kernel/git/jic23/iio into staging-next

Jonathan writes:

Third set of IIO new device support, features and cleanups for the 4.6 cycle.

Good to see several new contributors in this set - and more generally a
number of new 'faces' over this whole cycle.

Staging movements
* hmc5843
  - out of staging.
* periodic RTC trigger
  - driver dropped.  This is an ancient driver (brings back some memories ;)
  that was always somewhat of a bodge. Originally there was a driver that
  never went into mainline that supported large numbers of periodict timers
  on the PXA270 via this route. Discussions to have a generic periodic
  timer subsystem never went anywhere.  At the time RTC periodic
  interrupts were real - now they are emulated using high resolution
  timers so with the HRT driver this has become pointless.

New device support
* mpu6050 driver
  - Add support for the mpu6500.
* TI tpl0102 potentiometer
  - new driver.
* Vybrid SoC DAC
  - new driver.  The ADC on this SoC has been supported for a while, this
    adds a separate driver for the DAC.

New Features
* hmc5844
  - Attributes to configure the bias current (typically part of a self test)
    This could be done before via a somewhat obscure custom interface.
    This at least makes it easy to tell what is going on.
  - Document all custom attributes.
* mpu6050
  - Add support for calibration offset control and readback.
* ms5611
  - power regulator support.  This is always one that gets added the
    first time someone has a board that needs it.  Here it was needed,
    hence it was added.

Cleanups / minor fixes
* tree wide
  - clean up all the myriad different return values in response to a
    failure of i2c_check_functionality.  After discussions everyone seemed
    happy wiht -EOPNOTSUPP which seems to describe the situation well.
    I encouraged a tree wide cleanup to set a good example in future for
    this.
* core
  - Typos in the iio_event_spec documentation in iio.h
* afe4403
  - select REGMAP_SPI to avoid dependency issues
  - mark suspend/resume as __maybe_unused to avoid warnings
* afe4404
  - mark suspend/resume as __maybe_unused to avoid warnings
* atlas-ph-sensor
  - switch the regmap cache type from linear to rbtree to gain reading of
    registers on initial startup.  It's not immediately obvious, but
    regmap flat is meant for high performances cases so doesn't read these
    registers.
  - use regmap_bulk_read in one case where it was using
    i2c_smbus_read_i2c_block_data directly (unlike everything else that was
    through regmap).
* ina2xx
  - stype cleanups (lots of them!)
* isl29018
  - Get the struct device back from regmap rather than storing another
    copy of it in the private data.  This cleanup makes sense in a number
    of other drivers so patches may well follow.
* mpu6050
  - style cleanups (lots of them!)
  - improved return value handling
  - use usleep_range to avoid the usual issues with very short msleeps.
  - add some missing documentation.
* ms5611
  - use the probed device name for the device rather than the driver name.
  - select IIO_BUFFER to avoid dependency issues
* palmas
  - drop IRQF_EARLY_RESUME as no longer needed after genirq changes.
2016-03-01 16:31:55 -08:00
..
obsolete HID: roccat: Fixed resubmit: Deprecating most Roccat sysfs attributes 2015-10-21 11:54:42 +02:00
removed net_dma: simple removal 2014-09-28 07:05:16 -07:00
stable Drivers: hv: vmbus: Add vendor and device atttributes 2016-02-07 21:32:57 -08:00
testing iio: dac: vf610_dac: Add IIO DAC driver for Vybrid SoC 2016-02-24 20:52:55 +00:00
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.