Merge patch series "Add OP-TEE based RPMB driver for UFS devices"

Bean Huo <beanhuo@iokpp.de> says:

This patch series introduces OP-TEE based RPMB (Replay Protected
Memory Block) support for UFS devices, extending the kernel-level
secure storage capabilities that are currently available for eMMC
devices.

Previously, OP-TEE required a userspace supplicant to access RPMB
partitions, which created complex dependencies and reliability issues,
especially during early boot scenarios. Recent work by Linaro has
moved core supplicant functionality directly into the Linux kernel for
eMMC devices, eliminating userspace dependencies and enabling
immediate secure storage access. This series extends the same approach
to UFS devices, which are used in enterprise and mobile applications
that require secure storage capabilities.

Benefits:

 - Eliminates dependency on userspace supplicant for UFS RPMB access

 - Enables early boot secure storage access (e.g., fTPM, secure UEFI
   variables)

 - Provides kernel-level RPMB access as soon as UFS driver is
   initialized

 - Removes complex initramfs dependencies and boot ordering
   requirements

 - Ensures reliable and deterministic secure storage operations

 - Supports both built-in and modular fTPM configurations.

Prerequisites:
--------------

This patch series depends on commit 7e8242405b94 ("rpmb: move struct
rpmb_frame to common header") which has been merged into mainline
v6.18-rc2.

Link: https://patch.msgid.link/20251107230518.4060231-1-beanhuo@iokpp.de
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

1 files changed, 75 insertions, 0 deletions

diff --git a/Documentation/rust/coding-guidelines.rst b/Documentation/rust/coding-guidelines.rst
index 6ff9e754755d..3198be3a6d63 100644
--- a/Documentation/rust/coding-guidelines.rst
+++ b/Documentation/rust/coding-guidelines.rst
@@ -38,6 +38,81 @@ Like ``clang-format`` for the rest of the kernel, ``rustfmt`` works on
 individual files, and does not require a kernel configuration. Sometimes it may
 even work with broken code.
 
+Imports
+~~~~~~~
+
+``rustfmt``, by default, formats imports in a way that is prone to conflicts
+while merging and rebasing, since in some cases it condenses several items into
+the same line. For instance:
+
+.. code-block:: rust
+
+	// Do not use this style.
+	use crate::{
+	    example1,
+	    example2::{example3, example4, example5},
+	    example6, example7,
+	    example8::example9,
+	};
+
+Instead, the kernel uses a vertical layout that looks like this:
+
+.. code-block:: rust
+
+	use crate::{
+	    example1,
+	    example2::{
+	        example3,
+	        example4,
+	        example5, //
+	    },
+	    example6,
+	    example7,
+	    example8::example9, //
+	};
+
+That is, each item goes into its own line, and braces are used as soon as there
+is more than one item in a list.
+
+The trailing empty comment allows to preserve this formatting. Not only that,
+``rustfmt`` will actually reformat imports vertically when the empty comment is
+added. That is, it is possible to easily reformat the original example into the
+expected style by running ``rustfmt`` on an input like:
+
+.. code-block:: rust
+
+	// Do not use this style.
+	use crate::{
+	    example1,
+	    example2::{example3, example4, example5, //
+	    },
+	    example6, example7,
+	    example8::example9, //
+	};
+
+The trailing empty comment works for nested imports, as shown above, as well as
+for single item imports -- this can be useful to minimize diffs within patch
+series:
+
+.. code-block:: rust
+
+	use crate::{
+	    example1, //
+	};
+
+The trailing empty comment works in any of the lines within the braces, but it
+is preferred to keep it in the last item, since it is reminiscent of the
+trailing comma in other formatters. Sometimes it may be simpler to avoid moving
+the comment several times within a patch series due to changes in the list.
+
+There may be cases where exceptions may need to be made, i.e. none of this is
+a hard rule. There is also code that is not migrated to this style yet, but
+please do not introduce code in other styles.
+
+Eventually, the goal is to get ``rustfmt`` to support this formatting style (or
+a similar one) automatically in a stable release without requiring the trailing
+empty comment. Thus, at some point, the goal is to remove those comments.
+
 
 Comments
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