be3035e362
Recent Raspberry Pi firmware provides a mailbox property to detect under-voltage conditions. Here is the current definition. The u32 value returned by the firmware is divided into 2 parts: - lower 16-bits are the live value - upper 16-bits are the history or sticky value Bits: 0: undervoltage 1: arm frequency capped 2: currently throttled 16: undervoltage has occurred 17: arm frequency capped has occurred 18: throttling has occurred Signed-off-by: Stefan Wahren <stefan.wahren@i2se.com> Signed-off-by: Eric Anholt <eric@anholt.net> Reviewed-by: Eric Anholt <eric@anholt.net>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
See Documentation/00-INDEX for a list of what is contained in each file.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.