Merge branch 'for-next/imx'

2 files changed, 155 insertions, 0 deletions

diff --git a/Documentation/boards/imx.rst b/Documentation/boards/imx.rst
index 71cc6bb09a..8fe0a2828d 100644
--- a/Documentation/boards/imx.rst
+++ b/Documentation/boards/imx.rst
@@ -142,6 +142,79 @@ It must be included in the board's flash header:
 
 Analogous to HABv4 options and a template exist for HABv3.
 
+Secure Boot on i.MX6
+~~~~~~~~~~~~~~~~~~~~
+
+For most boards, the secure boot process on i.MX6 consist of the following image
+constellation::
+
+    0x0 +---------------------------------+
+        | Barebox Header                  |
+  0x400 +---------------------------------+       -
+        | i.MX IVT Header                 |       |
+        | Boot Data                       +--+    |
+        | CSF Pointer                     +--|-+  | Signed Area
+        +---------------------------------+  | |  |
+        | Device Configuration Data (DCD) |  | |  |
+ 0x1000 +---------------------------------+  | |  |
+        | Barebox Prebootloader (PBL)     |<-+ |  |
+        +---------------------------------+    |  |
+        | Piggydata (Main Barebox Binary) |    |  |
+        +---------------------------------+    |  -
+        | Command Sequence File (CSF)     |<---+
+        +---------------------------------+
+
+Here the Command Sequence File signs the complete Header, PBL and piggy data
+file. This ensures that the whole barebox binary is authenticated. This is
+possible since the DDR RAM is configured using the DCD and the whole DDR memory
+area can be used to load data onto the device for authentication.
+The boot ROM loads the CSF area and barebox into memory and uses the CSF to
+verify the complete barebox binary.
+
+Boards which do require a boot via SRAM, need changes akin to the implementation
+for i.MX8MQ described in the next chapter.
+
+Secure Boot on i.MX8MQ
+~~~~~~~~~~~~~~~~~~~~~~
+
+For i.MX8MQ the image has the following design::
+
+    0x0 +---------------------------------+
+        | Barebox Header                  |
+        +---------------------------------+
+        | i.MX IVT Header                 |
+        | HDMI Firmware (Signed by NXP)   |
+        +---------------------------------+        -
+        | i.MX IVT Header                 |        |
+        | Boot Data                       +--+     |
+        | CSF Pointer                     +--|-+   |
+        +---------------------------------+  | |   | Signed Area
+        | Device Configuration Data (DCD) |  | |   |
+        +---------------------------------+  | |   |
+        | Barebox Prebootloader (PBL)     |<-+ |   |
+        | Piggydata Hash (SHA256)         +----|-+ |
+        +---------------------------------+    | | -
+        | Command Sequence File (CSF)     |<---+ |
+        +---------------------------------+      | -
+        | Piggydata (Main Barebox Binary) |<-----+ | Hashed Area
+        +---------------------------------+        -
+
+In contrast to i.MX6, for the i.MX8MQ the piggydata can not be signed together
+with the PBL binary. The DDR memory is initialized during the start of the PBL,
+previous to this no access to the DDR memory is possible. Since the Tightly
+Coupled Memory used for early startup on i.MX8MQ has only 256Kib, the whole
+barebox can't be loaded and verified at once, since the complete barebox with
+firmware has a size of ~500Kib.
+
+The bootrom loads the HDMI firmware unconditionally, since it is signed by NXP.
+Afterwards the Prebootloader (PBL) is loaded into SRAM and the bootrom proceeds
+to verify the PBL according to the Command Sequence File (CSF). The verified
+PBL initializes the ARM Trusted Firmware (TF-A) and DDR RAM. It subsequently
+loads the piggydata from the boot media and calculates the sha256sum of the
+piggydata. This is compared to the sha256sum built into the PBL during compile
+time, the PBL will only continue to boot if the sha256sum matches the builtin
+sha256sum.
+
 Using GPT on i.MX
 ^^^^^^^^^^^^^^^^^
 
diff --git a/Documentation/boards/imx/embest-marsboard.rst b/Documentation/boards/imx/embest-marsboard.rst
new file mode 100644
index 0000000000..bdaa0880ae
--- /dev/null
+++ b/Documentation/boards/imx/embest-marsboard.rst
@@ -0,0 +1,82 @@
+Embest MarS Board
+=================
+
+Board comes with:
+
+* 1G DDR3 SDRAM
+* 4G eMMC
+* 2M SPI-NOR Flash
+
+Layout::
+
+  .-----------------------------------------------------.
+  |O                                    OTG-->| V |    O|
+  |                              SW1    USB   '---'  .--|
+  |             .-----------.    v.---.           .->| <|
+  |             |           |    1|o--| O         |  `--|
+  |             | i.MX6Dual |    2|--o| N        Debug  |
+  |             |    SoC    |     `---'          USB    |
+  |             |           |                           |
+  |             `-----------'                           |
+  |                                                     |
+  |                                                     |
+  |                                                     |
+  |                                                     |
+  |O                                                   O|
+  `-----------------------------------------------------'
+
+Boot Configuration
+==================
+
+DIP Switch ``SW1`` on the board can be used to set ``BOOT_MODE1`` and
+``BOOT_MODE0`` going to the i.MX6:
+
+Set ``SW1 = 01`` for serial boot::
+
+        SW1
+        v.---.
+        1|o--| O
+        2|--o| N
+         `---'
+
+Set ``SW1 = 10`` for internal (SPI-NOR Flash) boot::
+
+        SW1
+        v.---.
+        1|--o| O
+        2|o--| N
+         `---'
+
+Set ``SW1 = 00`` for boot from eFuses::
+
+        SW1
+        v.---.
+        1|o--| O
+        2|o--| N
+         `---'
+
+Flashing barebox
+----------------
+
+  1. Connect to the board's Debug Mini-USB (115200 8N1)
+
+  2. Set ``SW1 = 01`` for serial boot mode (see above)
+
+  3. Turn board's power on
+
+  4. Upload barebox image to the board via imx-usb-loader
+
+.. code-block:: none
+
+  host$ imx-usb-loader images/barebox-embest-imx6q-marsboard.img
+..
+
+  4. Flash barebox to SPI-NOR Flash via Android Fastboot
+
+.. code-block:: none
+
+  host$ fastboot flash bbu-spiflash images/barebox-embest-imx6q-marsboard.img
+
+..
+
+  5. Restore ``SW1 = 10`` for internal (SPI-NOR) boot (see above)