board: amlogic: vim3: add support for dynamic PCIe enable
The VIM3 on-board MCU can mux the PCIe/USB3.0 shared differential
lines using a FUSB340TMX USB 3.1 SuperSpeed Data Switch between
an USB3.0 Type A connector and a M.2 Key M slot.
The PHY driving these differential lines is shared between
the USB3.0 controller and the PCIe Controller, thus only
a single controller can use it.
This adds this dynamic switching right before booting Linux
and the configuration steps in the boards documentation.
Signed-off-by: Neil Armstrong <narmstrong@baylibre.com>
Reviewed-by: Kevin Hilman <khilman@baylibre.com>
Tested-by: Kevin Hilman <khilman@baylibre.com>
[narmstrong: fixed warning by replacing min() by min_t()]
diff --git a/doc/board/amlogic/khadas-vim3.rst b/doc/board/amlogic/khadas-vim3.rst
index c1c0321..d6a9642 100644
--- a/doc/board/amlogic/khadas-vim3.rst
+++ b/doc/board/amlogic/khadas-vim3.rst
@@ -18,6 +18,33 @@
Schematics are available on the manufacturer website.
+PCIe Setup
+----------
+The VIM3 on-board MCU can mux the PCIe/USB3.0 shared differential
+lines using a FUSB340TMX USB 3.1 SuperSpeed Data Switch between
+an USB3.0 Type A connector and a M.2 Key M slot.
+The PHY driving these differential lines is shared between
+the USB3.0 controller and the PCIe Controller, thus only
+a single controller can use it.
+
+To setup for PCIe, run the following commands from U-Boot:
+
+.. code-block:: none
+
+ i2c dev i2c@5000
+ i2c mw 0x18 0x33 1
+
+Then power-cycle the board.
+
+To set back to USB3.0, run the following commands from U-Boot:
+
+.. code-block:: none
+
+ i2c dev i2c@5000
+ i2c mw 0x18 0x33 0
+
+Then power-cycle the board.
+
U-Boot compilation
------------------