Documentation/i2c/writing-clients.rst

File Facts

System

Linux kernel

Corpus path

Documentation/i2c/writing-clients.rst

Extension

.rst

Size

14314 bytes

Lines

404

Domain

Support Tooling And Documentation

Bucket

Documentation

Inferred role

Support Tooling And Documentation: exported/initcall integration point

Status

integration implementation candidate

Why This File Exists

Repository support layer: documentation, build tooling, samples, user-space helper tools, generated initramfs support, licenses, and validation utilities.

• Repository support layer: documentation, build tooling, samples, user-space helper tools, generated initramfs support, licenses, and validation utilities.
• Exports symbols or registers init work; inspect boot/module ordering and who consumes the exported contract.
• Defines or uses C structs; map object ownership, embedded links, reference counts, and lock ownership.

Dependency Surface

• No C-style include directives detected by the generator.

Detected Declarations

• function remove
• function foo_write_value
• function probe
• function foo_cleanup
• module init foo_init

Annotated Snippet

module_init(foo_init);

  static void __exit foo_cleanup(void)
  {
	i2c_del_driver(&foo_driver);
  }
  module_exit(foo_cleanup);

  The module_i2c_driver() macro can be used to reduce above code.

  module_i2c_driver(foo_driver);

Note that some functions are marked by ``__init``.  These functions can
be removed after kernel booting (or module loading) is completed.
Likewise, functions marked by ``__exit`` are dropped by the compiler when
the code is built into the kernel, as they would never be called.


Driver Information
==================

::

  /* Substitute your own name and email address */
  MODULE_AUTHOR("Frodo Looijaard <frodol@dds.nl>"
  MODULE_DESCRIPTION("Driver for Barf Inc. Foo I2C devices");

  /* a few non-GPL license types are also allowed */
  MODULE_LICENSE("GPL");


Power Management
================

If your I2C device needs special handling when entering a system low
power state -- like putting a transceiver into a low power mode, or
activating a system wakeup mechanism -- do that by implementing the
appropriate callbacks for the dev_pm_ops of the driver (like suspend
and resume).

These are standard driver model calls, and they work just like they
would for any other driver stack.  The calls can sleep, and can use
I2C messaging to the device being suspended or resumed (since their
parent I2C adapter is active when these calls are issued, and IRQs
are still enabled).


System Shutdown
===============

If your I2C device needs special handling when the system shuts down
or reboots (including kexec) -- like turning something off -- use a
shutdown() method.

Again, this is a standard driver model call, working just like it
would for any other driver stack:  the calls can sleep, and can use
I2C messaging.


Command function
================

A generic ioctl-like function call back is supported. You will seldom
need this, and its use is deprecated anyway, so newer design should not
use it.


Sending and receiving
=====================

Annotation

• Detected declarations: `function remove`, `function foo_write_value`, `function probe`, `function foo_cleanup`, `module init foo_init`.
• Atlas domain: Support Tooling And Documentation / Documentation.
• Implementation status: integration implementation candidate.

Implementation Notes

• This generated page is the file-by-file coverage layer; curated subsystem chapters should link here when they synthesize a multi-file control flow.
• Core OS pages should be promoted from atlas-only to deep-reviewed when they explain data structures, invariants, locking, lifecycle, and C implementation snippets.
• Driver-family pages are intentionally pattern-oriented unless they are part of the selected PCIe/NVMe representative device path.