doc: api: bootcount: Convert to rST documentation

Move to the new documentation style with rST formatting.

Signed-off-by: Vasileios Amoiridis <vasileios.amoiridis@cern.ch>

1 files changed, 58 insertions, 0 deletions

diff --git a/doc/api/bootcount.rst b/doc/api/bootcount.rst
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+.. SPDX-License-Identifier: GPL-2.0+
+
+Boot Count Limit
+================
+
+This is enabled by CONFIG_BOOTCOUNT_LIMIT.
+
+This allows to detect multiple failed attempts to boot Linux.
+
+After a power-on reset, the ``bootcount`` variable will be initialized to 1, and
+each reboot will increment the value by 1.
+
+If, after a reboot, the new value of ``bootcount`` exceeds the value of
+``bootlimit``, then instead of the standard boot action (executing the contents
+of ``bootcmd``), an alternate boot action will be performed, and the contents of
+``altbootcmd`` will be executed.
+
+If the variable ``bootlimit`` is not defined in the environment, the Boot Count
+Limit feature is disabled. If it is enabled, but ``altbootcmd`` is not defined,
+then U-Boot will drop into interactive mode and remain there.
+
+It is the responsibility of some application code (typically a Linux
+application) to reset the variable ``bootcount`` to 0 when the system booted
+successfully, thus allowing for more boot cycles.
+
+CONFIG_BOOTCOUNT_FS
+--------------------
+
+This adds support for maintaining boot count in a file on a filesystem.
+Tested filesystems are FAT and EXT. The file to use is defined by:
+
+CONFIG_SYS_BOOTCOUNT_FS_INTERFACE
+CONFIG_SYS_BOOTCOUNT_FS_DEVPART
+CONFIG_SYS_BOOTCOUNT_FS_NAME
+
+The format of the file is:
+
+.. list-table::
+   :header-rows: 1
+
+   * - type
+     - entry
+   * - u8
+     - magic
+   * - u8
+     - version
+   * - u8
+     - bootcount
+   * - u8
+     - upgrade_available
+
+To prevent unattended usage of ``altbootcmd``, the ``upgrade_available``
+variable is used.
+If ``upgrade_available`` is 0, ``bootcount`` is not saved.
+If ``upgrade_available`` is 1, ``bootcount`` is saved.
+So a userspace application should take care of setting the ``upgrade_available``
+and ``bootcount`` variables to 0, if the system boots successfully.
+This also avoids writing the ``bootcount`` information on all reboots.