ECPIX-5 support

[paulusmack]

The ECPIX-5 is a FPGA development board from Lambda Concepts with a Lattice ECP5 FPGA and lots of other stuff, including 512MiB of DRAM, 32MiB of SPI flash memory, gigabit ethernet PHY, micro SD card slot, USB2, USB3, HDMI and SATA interfaces, and 8 PMOD slots. It comes in 45K and 85K LUT versions.

This adds basic support for Microwatt on the 85K LUT version of the ECPIX-5, including support for the DRAM, flash memory, ethernet and SD card.

Note that the verilog for litedram, liteeth and litesdcard have been regenerated from recent upstream Litex for all supported targets. I have tested the arty_a7-100 target (and obviously ECPIX-5) but not any of the others.

[mikey]

Can we add this to CI also? something like this should do it:

diff --git a/.github/workflows/test.yml b/.github/workflows/test.yml
index cf220669fa..52db2cdc6e 100644
--- a/.github/workflows/test.yml
+++ b/.github/workflows/test.yml
@@ -73,7 +73,7 @@ jobs:
       fail-fast: false
       max-parallel: 2
       matrix:
-        task: [ ECP5-EVN, ORANGE-CRAB, ORANGE-CRAB-0.21 ]
+        task: [ ECP5-EVN, ORANGE-CRAB, ORANGE-CRAB-0.21, ECPIX-5 ]
     runs-on: ubuntu-latest
     env:
       DOCKER: 1

[paulusmack]

I should mention that the litesdcard verilog was generated by a modified litesdcard tree, which is published at https://github.com/paulusmack/litesdcard (master branch). I have put in a pull request for it, but it hasn't been picked up yet. I don't see why it would be controversial, since it's just exporting a couple of buffer direction control signals that already exist. We need them on the ECPIX-5 to control an external buffer chip between the FPGA and the micro SD card slot.