Documentation: i.MX8M: add EVK QSPI NOR barebox installation documentation

Document the steps required to flash the barebox image to a QSPI NOR
flash. This can be helpful if the user-space wants to update the QSPI
NOR barebox image. These steps can be skipped if barebox is updated by
the qspi bbu-handler.

Signed-off-by: Marco Felsch <m.felsch@pengutronix.de>
Link: https://lore.barebox.org/20230228-v2023-02-0-topic-flexspi-v2-23-3d33126d2434@pengutronix.de
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

3 files changed, 35 insertions, 0 deletions

diff --git a/Documentation/boards/imx/nxp-imx8mm-evk.rst b/Documentation/boards/imx/nxp-imx8mm-evk.rst
index f0dfc53ed0..aa70419139 100644
--- a/Documentation/boards/imx/nxp-imx8mm-evk.rst
+++ b/Documentation/boards/imx/nxp-imx8mm-evk.rst
@@ -85,5 +85,16 @@ installation to the eMMC boot partition requires special handling:
     then afterwards, the newly written boot partition is activated
     (This is controlled by the barebox ``mmcX.boot`` variable).
 
+The following steps are required to write the image to the QSPI NOR flash:
+
+  - The 32KiB preamble MMC preamble must be stripped.
+
+  - The QSPI NOR partition ``barebox`` must be erased before the stripped
+    image is written. The erase size depends on the stripped image size but
+    always start at offset 0.
+
+  - Write the stripped barebox image to the QSPI NOR partition ``barebox``
+    at offset 0.
+
 The ``barebox_update`` command takes care of this and need just be
 supplied a barebox image as argument.
diff --git a/Documentation/boards/imx/nxp-imx8mn-evk.rst b/Documentation/boards/imx/nxp-imx8mn-evk.rst
index 177fc59c10..597db57eaf 100644
--- a/Documentation/boards/imx/nxp-imx8mn-evk.rst
+++ b/Documentation/boards/imx/nxp-imx8mn-evk.rst
@@ -80,5 +80,17 @@ installation to the eMMC boot partition requires special handling:
     start at an offset when booting from eMMC boot partitions, thus the first
     32KiB must be stripped.
 
+The following steps are required to write the image to the QSPI NOR flash:
+
+  - Strip the 32KiB preamble, like it is done for the eMMC boot partition case
+    (see above).
+
+  - The QSPI NOR partition ``barebox`` must be erased before the stripped
+    image is written. The erase size depends on the stripped image size but
+    always start at offset 0.
+
+  - Write the stripped barebox image to the QSPI NOR partition ``barebox``
+    at offset 0.
+
 The ``barebox_update`` command takes care of this and need just be
 supplied a barebox image as argument.
diff --git a/Documentation/boards/imx/nxp-imx8mp-evk.rst b/Documentation/boards/imx/nxp-imx8mp-evk.rst
index 53cdd904ab..cfd1153e15 100644
--- a/Documentation/boards/imx/nxp-imx8mp-evk.rst
+++ b/Documentation/boards/imx/nxp-imx8mp-evk.rst
@@ -88,5 +88,17 @@ installation to the eMMC boot partition requires special handling:
     start at an offset when booting from eMMC boot partitions, thus the first
     32KiB must be stripped.
 
+The following steps are required to write the image to the QSPI NOR flash:
+
+  - Strip the 32KiB preamble, like it is done for the eMMC boot partition case
+    (see above).
+
+  - The QSPI NOR partition ``barebox`` must be erased before the stripped
+    image is written. The erase size depends on the stripped image size but
+    always start at offset 0.
+
+  - Write the stripped barebox image to the QSPI NOR partition ``barebox``
+    at offset 0.
+
 The ``barebox_update`` command takes care of this and need just be
 supplied a barebox image as argument.