doc: tfm: generalize info about UART

Edited tfm_logging.rst page not to mention UART0 as the only
peripheral that can be used for logging.
NCSDK-33550.

Signed-off-by: Grzegorz Ferenc <[email protected]>

Author: greg-fer

doc/nrf/releases_and_maturity/releases/release-notes-changelog.rst

@@ -120,6 +120,7 @@ Security
 
 * Added the new section about :ref:`ug_crypto_index`.
   The new section includes pages about :ref:`ug_crypto_architecture` (new page) and :ref:`crypto_drivers` (moved from :ref:`nrf_security` library).
+* Updated the :ref:`ug_tfm_logging` page with more details about how to configure logging on the same UART instance as the application for nRF5340 and nRF91 Series devices.
 
 Protocols
 =========

doc/nrf/security/tfm/tfm_logging.rst

@@ -9,25 +9,43 @@ TF-M logging
    :depth: 2
 
 TF-M employs two UART interfaces for logging: one for the :ref:`Secure Processing Environment<app_boards_spe_nspe>` (including MCUboot and TF-M), and one for the :ref:`Non-Secure Processing Environment<app_boards_spe_nspe>` (including user application).
-By default, the logs arrive on different COM ports on the host PC.
 
-Configuring logging
-*******************
+By default, the logs from Nordic Semiconductor's Development Kits (DKs) arrive on different COM ports on the host PC.
+The UART instances can vary by device family:
 
-You can configure the TF-M to connect to the same UART as the application with the :kconfig:option:`CONFIG_TFM_SECURE_UART0` Kconfig option.
-Setting this Kconfig option makes TF-M logs visible on the application's VCOM, without manual connection.
+* nRF5340 and nRF91 Series: The application typically uses the UART instance ``0`` (``uart0``), and TF-M uses the UART instance ``1`` (``uart1``) by default.
+* nRF54L Series: The application typically uses the UART instance ``20`` (``uart20``), and TF-M uses the UART instance ``30`` (``uart30``) by default.
 
-The UART instance used by the application is ``0`` by default, and the TF-M UART instance is ``1``.
-To change the TF-M UART instance to the same as that of the application's, use the :kconfig:option:`CONFIG_TFM_SECURE_UART0` Kconfig option.
+For more information about the logging in the |NCS|, see :ref:`ug_logging`.
 
-When building TF-M with logging enabled, UART1 must be disabled in the non-secure application, otherwise the non-secure application will fail to run.
-The recommended way to do this is to copy the :file:`.overlay` file from the :ref:`tfm_hello_world` sample.
+Configuring logging to the same UART as the application
+*******************************************************
 
 .. note::
-   When the TF-M and the user application use the same UART, the TF-M disables logging after it has booted and re-enables it again only to log a fatal error.
+   This option is not available to nRF54L Series devices.
+
+For nRF5340 and nRF91 Series devices, you can configure TF-M to connect to the same UART as the application.
+Setting the appropriate Kconfig option makes TF-M logs automatically visible on the application's UART.
+
+To configure TF-M to connect to the same UART as the application, you can use the ``CONFIG_TFM_SECURE_UART`` Kconfig options, for example :kconfig:option:`CONFIG_TFM_SECURE_UART0` for the example above.
+
+When building TF-M with logging enabled, UART instance used by TF-M must be disabled in the non-secure application, otherwise the non-secure application will fail to run.
+The recommended way to do this is by setting it in an :file:`.overlay` file.
+For example, assuming TF-M uses the ``uart1`` instance and :kconfig:option:`CONFIG_TFM_SECURE_UART0` is set, you can disable TF-M's UART instance in the devicetree overlay file like this:
+
+.. code-block:: dts
+
+   &uart1 {
+	        status = "disabled";
+   };
+
+See :ref:`zephyr:set-devicetree-overlays` in the Zephyr documentation for more information about configuring devicetree overlays and :ref:`cmake_options` in the |NCS| documentation for how to provide overlay files to the build system.
+
+.. note::
+   When TF-M and the user application use the same UART, TF-M disables logging after it has booted and re-enables it again only to log a fatal error.
 
 Disabling logging
-=================
+*****************
 
 To disable logging, enable the :kconfig:option:`CONFIG_TFM_LOG_LEVEL_SILENCE` option.
 

doc/nrf/security/tfm/tfm_supported_services.rst

@@ -188,7 +188,7 @@ These are the main differences:
 * Logging:
 
   * The |NCS| provides enhanced :ref:`logging capabilities <ug_tfm_logging>` with options to configure UART instances.
-  * The |NCS| allows TF-M and the application to share the same UART for logging.
+    For nRF5340 and nRF91 Series devices, the |NCS| allows TF-M and the application to share the same UART for logging.
 
 * Security features: