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Add support for Partial-IO poweroff. In Partial-IO pins of a few hardware units can generate system wakeups while DDR memory is not powered resulting in a fresh boot of the system. These hardware units in the SoC are always powered so that some logic can detect pin activity. If the system supports Partial-IO as described in the fw capabilities, a sys_off handler is added. This sys_off handler decides if the poweroff is executed by entering normal poweroff or Partial-IO instead. The decision is made by checking if wakeup is enabled on all devices that may wake up the SoC from Partial-IO. The possible wakeup devices are found by checking which devices reference a "Partial-IO" system state in the list of wakeup-source system states. Only devices that are actually enabled by the user will be considered as an active wakeup source. If none of the wakeup sources is enabled the system will do a normal poweroff. If at least one wakeup source is enabled it will instead send a TI_SCI_MSG_PREPARE_SLEEP message from the sys_off handler. Sending this message will result in an immediate shutdown of the system. No execution is expected after this point. The code will wait for 5s and do an emergency_restart afterwards if Partial-IO wasn't entered at that point. A short documentation about Partial-IO can be found in section 6.2.4.5 of the TRM at https://www.ti.com/lit/pdf/spruiv7 Signed-off-by: Markus Schneider-Pargmann (TI.com) <msp@baylibre.com> Reviewed-by: Dhruva Gole <d-gole@ti.com> Reviewed-by: Kendall Willis <k-willis@ti.com> Reviewed-by: Sebin Francis <sebin.francis@ti.com> Link: https://patch.msgid.link/20251103-topic-am62-partialio-v6-12-b4-v10-2-0557e858d747@baylibre.com Signed-off-by: Nishanth Menon <nm@ti.com>
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 reStructuredText markup notation.
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.