linux/Documentation/ABI
Linus Torvalds 822ef14e9d ARM: SoC driver updates for v5.9
A couple of subsystems have their own subsystem maintainers but choose
 to have the code merged through the soc tree as upstream, as the code
 tends to be used across multiple SoCs or has SoC specific drivers itself:
 
  - memory controllers:
      Krzysztof Kozlowski takes ownership of the drivers/memory
      subsystem and its drivers, starting out with a set of cleanup
      patches.
      A larger driver for the Tegra memory controller that was accidentally
      missed for v5.8 is now added.
 
  - reset controllers:
      Only minor updates to drivers/reset this time
 
  - firmware:
      The "turris mox" firmware driver gains support for signed firmware blobs
      The tegra firmware driver gets extended to export some debug information
      Various updates to i.MX firmware drivers, mostly cosmetic
 
  - ARM SCMI/SCPI:
      A new mechanism for platform notifications is added, among a number
      of minor changes.
 
  - optee:
      Probing of the TEE bus is rewritten to better support detection of
      devices that depend on the tee-supplicant user space.
      A new firmware based trusted platform module (fTPM) driver is added
      based on OP-TEE
 
  - SoC attributes:
      A new driver is added to provide a generic soc_device for identifying
      a machine through the SMCCC ARCH_SOC_ID firmware interface rather than
      by probing SoC family specific registers.
      The series also contains some cleanups to the common soc_device code.
 
 There are also a number of updates to SoC specific drivers,
 the main ones are:
 
  - Mediatek cmdq driver gains a few in-kernel interfaces
 
  - Minor updates to Qualcomm RPMh, socinfo, rpm drivers, mostly adding
    support for additional SoC variants
 
  - The Qualcomm GENI core code gains interconnect path voting and
    performance level support, and integrating this into a number of
    device drivers.
 
  - A new driver for Samsung Exynos5800 voltage coupler for
 
  - Renesas RZ/G2H (R8A774E1) SoC support gets added to a couple of SoC
    specific device drivers
 
  - Updates to the TI K3 Ring Accelerator driver
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Merge tag 'arm-drivers-5.9' of git://git.kernel.org/pub/scm/linux/kernel/git/soc/soc

Pull ARM SoC driver updates from Arnd Bergmann:
 "A couple of subsystems have their own subsystem maintainers but choose
  to have the code merged through the soc tree as upstream, as the code
  tends to be used across multiple SoCs or has SoC specific drivers
  itself:

   - memory controllers:

     Krzysztof Kozlowski takes ownership of the drivers/memory subsystem
     and its drivers, starting out with a set of cleanup patches.

     A larger driver for the Tegra memory controller that was
     accidentally missed for v5.8 is now added.

   - reset controllers:

     Only minor updates to drivers/reset this time

   - firmware:

     The "turris mox" firmware driver gains support for signed firmware
     blobs The tegra firmware driver gets extended to export some debug
     information Various updates to i.MX firmware drivers, mostly
     cosmetic

   - ARM SCMI/SCPI:

     A new mechanism for platform notifications is added, among a number
     of minor changes.

   - optee:

     Probing of the TEE bus is rewritten to better support detection of
     devices that depend on the tee-supplicant user space. A new
     firmware based trusted platform module (fTPM) driver is added based
     on OP-TEE

   - SoC attributes:

     A new driver is added to provide a generic soc_device for
     identifying a machine through the SMCCC ARCH_SOC_ID firmware
     interface rather than by probing SoC family specific registers.

     The series also contains some cleanups to the common soc_device
     code.

  There are also a number of updates to SoC specific drivers, the main
  ones are:

   - Mediatek cmdq driver gains a few in-kernel interfaces

   - Minor updates to Qualcomm RPMh, socinfo, rpm drivers, mostly adding
     support for additional SoC variants

   - The Qualcomm GENI core code gains interconnect path voting and
     performance level support, and integrating this into a number of
     device drivers.

   - A new driver for Samsung Exynos5800 voltage coupler for

   - Renesas RZ/G2H (R8A774E1) SoC support gets added to a couple of SoC
     specific device drivers

   - Updates to the TI K3 Ring Accelerator driver"

* tag 'arm-drivers-5.9' of git://git.kernel.org/pub/scm/linux/kernel/git/soc/soc: (164 commits)
  soc: qcom: geni: Fix unused label warning
  soc: qcom: smd-rpm: Fix kerneldoc
  memory: jz4780_nemc: Only request IO memory the driver will use
  soc: qcom: pdr: Reorder the PD state indication ack
  MAINTAINERS: Add Git repository for memory controller drivers
  memory: brcmstb_dpfe: Fix language typo
  memory: samsung: exynos5422-dmc: Correct white space issues
  memory: samsung: exynos-srom: Correct alignment
  memory: pl172: Enclose macro argument usage in parenthesis
  memory: of: Correct kerneldoc
  memory: omap-gpmc: Fix language typo
  memory: omap-gpmc: Correct white space issues
  memory: omap-gpmc: Use 'unsigned int' for consistency
  memory: omap-gpmc: Enclose macro argument usage in parenthesis
  memory: omap-gpmc: Correct kerneldoc
  memory: mvebu-devbus: Align with open parenthesis
  memory: mvebu-devbus: Add missing braces to all arms of if statement
  memory: bt1-l2-ctl: Add blank lines after declarations
  soc: TI knav_qmss: make symbol 'knav_acc_range_ops' static
  firmware: ti_sci: Replace HTTP links with HTTPS ones
  ...
2020-08-03 19:30:59 -07:00
..
obsolete Power management updates for 5.8-rc1 2020-06-02 13:17:23 -07:00
removed powerpc updates for 5.7 2020-04-05 11:12:59 -07:00
stable Documentation/ABI: Add new attribute for mlxreg-io sysfs interfaces 2020-07-15 12:45:07 +03:00
testing ARM: SoC driver updates for v5.9 2020-08-03 19:30:59 -07:00
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/process/stable-api-nonsense.rst.