[PATCH v4 7/7] doc: board: Add document for DFU boot on am62x SoCs

[Sjoerd Simons]

Both AM62 SK and beagleplay support DFU boot in a similar way now;
Document how to actually run DFU boot for both boards

Signed-off-by: Sjoerd Simons <sjoerd at collabora.com>

---

Changes in v4:
- New patch

 doc/board/beagle/am62x_beagleplay.rst | 12 +++++++++
 doc/board/ti/am62x_sk.rst             | 37 +++++++++++++++++++++++++++
 2 files changed, 49 insertions(+)

diff --git a/doc/board/beagle/am62x_beagleplay.rst b/doc/board/beagle/am62x_beagleplay.rst
index 7784e62b0b7..4c8b0845845 100644
--- a/doc/board/beagle/am62x_beagleplay.rst
+++ b/doc/board/beagle/am62x_beagleplay.rst
@@ -270,6 +270,18 @@ for details.
 To switch to SD card boot mode, hold the USR button while powering on
 with Type-C power supply, then release when power LED lights up.
 
+DFU based boot
+--------------
+
+To boot the board over DFU, ensure there is no SD card inserted with a
+bootloader. Hold the USR switch while plugging into the Type C to boot into DFU
+mode. After power-on the build artifacts needs to be uploaded one by one with a
+tool like dfu-util.
+
+.. include::  ../ti/am62x_sk.rst
+    :start-after: .. am62x_evm_rst_include_start_dfu_boot
+    :end-before: .. am62x_evm_rst_include_end_dfu_boot
+
 Debugging U-Boot
 ----------------
 
diff --git a/doc/board/ti/am62x_sk.rst b/doc/board/ti/am62x_sk.rst
index b12dc85f06b..904a54cd5ff 100644
--- a/doc/board/ti/am62x_sk.rst
+++ b/doc/board/ti/am62x_sk.rst
@@ -105,6 +105,20 @@ Set the variables corresponding to this platform:
 
 * 3.1 R5:
 
+.. include::  ../ti/k3.rst
+    :start-after: .. k3_rst_include_start_build_steps_spl_r5
+    :end-before: .. k3_rst_include_end_build_steps_spl_r5
+
+* 3.1.1 Alternatively build R5 for DFU boot:
+
+As the SPL size can get to big when building with support for booting both from
+local storage *and* DFU an extra config fragment should be used to enable DFU
+support (and disable storage support)
+
+.. prompt:: bash $
+
+  export UBOOT_CFG_CORTEXR=${UBOOT_CFG_CORTEXR} am62x_r5_usbdfu.config
+
 .. include::  ../ti/k3.rst
     :start-after: .. k3_rst_include_start_build_steps_spl_r5
     :end-before: .. k3_rst_include_end_build_steps_spl_r5
@@ -251,6 +265,29 @@ https://www.ti.com/lit/pdf/spruiv7 under the `Boot Mode Pins` section.
 
 For SW2 and SW1, the switch state in the "ON" position = 1.
 
+DFU based boot
+--------------
+
+To boot the board over DFU, set the switches to DFU mode and connect to the
+USB Type C DRD Port on the board. After power-on the build artifacts needs to be
+uploaded one by one with a tool like dfu-util.
+
+.. am62x_evm_rst_include_start_dfu_boot
+
+The initial ROM will have a DFU alt named `bootloader` for the initial R5 spl
+upload. The next stages as exposed by u-boot have target alts matching the name
+of the artifacts, for these a USB reset has to be done after each upload.
+
+When using dfu-util the following commands can be used to boot to a u-boot shell:
+
+.. prompt:: bash $
+
+  dfu-util -a bootloader -D tiboot3.bin
+  dfu-util -R -a tispl -D tispl.bin
+  dfu-util -R -a u-boot.img -D u-boot.img
+
+.. am62x_evm_rst_include_end_dfu_boot
+
 Debugging U-Boot
 ----------------
 
-- 
2.43.0