samples/drivers/soc_flash_nrf: Add missing README.rst

Missing documentation added.

Fixes zephyrproject-rtos#53753

Signed-off-by: Dominik Ermel <[email protected]>

samples/drivers/soc_flash_nrf/README.rst

@@ -0,0 +1,132 @@
+.. _soc-flash-nrf-sample:
+
+nRF SoC flash sample
+####################
+
+Overview
+********
+
+This sample demonstrates using the flash API on a SoC internal flash.
+The sample uses :ref:`flash_map_api` to obtain device for flash, using
+DTS node label, and then directly uses :ref:`flash_api` to perform
+flash operations.
+
+Within the sample user may observe how read/write/erase operations
+are performed on a device and how to first check whether device is
+ready for operation.
+
+Building and Running
+********************
+
+The application will build for any SoC with internal flash memory
+access enabled, as it is default for SoC devices, and fixed-partition
+defined over that internal flash labeled `slot1_partition`, when
+:kconfig:option:`CONFIG_TRUSTED_EXECUTION_NONSECURE` is not selected,
+or `slot1_ns_partition`, when the Kconfig option is selected.
+
+.. zephyr-app-commands::
+   :zephyr-app: samples/drivers/soc_flash_nrf
+   :board: nrf52840dk_nrf52840
+   :goals: build flash
+   :compact:
+
+Sample Output
+=============
+
+.. code-block:: console
+
+   *** Booting Zephyr OS build v2.7.99-17621-g54832687bcbb ***
+
+   Nordic nRF5 Flash Testing
+   =========================
+
+   Test 1: Flash erase page at 0x82000
+      Flash erase succeeded!
+
+   Test 2: Flash write (word array 1)
+      Attempted to write 1122 at 0x82000
+      Attempted to read 0x82000
+      Data read: 1122
+      Data read matches data written. Good!
+      Attempted to write aabb at 0x82004
+      Attempted to read 0x82004
+      Data read: aabb
+      Data read matches data written. Good!
+      Attempted to write abcd at 0x82008
+      Attempted to read 0x82008
+      Data read: abcd
+      Data read matches data written. Good!
+      Attempted to write 1234 at 0x8200c
+      Attempted to read 0x8200c
+      Data read: 1234
+      Data read matches data written. Good!
+
+   Test 3: Flash erase (4 pages at 0x80000)
+      Flash erase succeeded!
+
+   Test 4: Flash write (word array 2)
+      Attempted to write 1234 at 0x82000
+      Attempted to read 0x82000
+      Data read: 1234
+      Data read matches data written. Good!
+      Attempted to write aabb at 0x82004
+      Attempted to read 0x82004
+      Data read: aabb
+      Data read matches data written. Good!
+      Attempted to write abcd at 0x82008
+      Attempted to read 0x82008
+      Data read: abcd
+      Data read matches data written. Good!
+      Attempted to write 1122 at 0x8200c
+      Attempted to read 0x8200c
+      Data read: 1122
+      Data read matches data written. Good!
+
+   Test 5: Flash erase page at 0x82000
+      Flash erase succeeded!
+
+   Test 6: Non-word aligned write (word array 3)
+      Attempted to write 1122 at 0x82001
+      Attempted to read 0x82001
+      Data read: 1122
+      Data read matches data written. Good!
+      Attempted to write aabb at 0x82005
+      Attempted to read 0x82005
+      Data read: aabb
+      Data read matches data written. Good!
+      Attempted to write abcd at 0x82009
+      Attempted to read 0x82009
+      Data read: abcd
+      Data read matches data written. Good!
+      Attempted to write 1234 at 0x8200d
+      Attempted to read 0x8200d
+      Data read: 1234
+      Data read matches data written. Good!
+      Attempted to write 1122 at 0x82011
+      Attempted to read 0x82011
+      Data read: 1122
+      Data read matches data written. Good!
+      Attempted to write aabb at 0x82015
+      Attempted to read 0x82015
+      Data read: aabb
+      Data read matches data written. Good!
+      Attempted to write abcd at 0x82019
+      Attempted to read 0x82019
+      Data read: abcd
+      Data read matches data written. Good!
+      Attempted to write 1234 at 0x8201d
+      Attempted to read 0x8201d
+      Data read: 1234
+      Data read matches data written. Good!
+
+   Test 7: Page layout API
+      Offset  0x00041234:
+        belongs to the page 65 of start offset 0x00041000
+        and the size of 0x00001000 B.
+      Page of number 37 has start offset 0x00025000
+        and size of 0x00001000 B.
+        Page index resolved properly
+      SoC flash consists of 256 pages.
+
+   Test 8: Write block size API
+      write-block-size = 1