Factor out SPI flash resource definition.

2 files changed, 37 insertions, 0 deletions

diff --git a/nmigen_boards/dev/__init__.py b/nmigen_boards/dev/__init__.py
new file mode 100644
index 0000000..b27acfa
--- /dev/null
+++ b/nmigen_boards/dev/__init__.py
@@ -0,0 +1 @@
+from .flash import SPIFlashResources
diff --git a/nmigen_boards/dev/flash.py b/nmigen_boards/dev/flash.py
new file mode 100644
index 0000000..a4b5e33
--- /dev/null
+++ b/nmigen_boards/dev/flash.py
@@ -0,0 +1,36 @@
+from nmigen.build import *
+
+
+__all__ = ["SPIFlashResources"]
+
+
+def SPIFlashResources(number, *, cs_n, clk, mosi, miso, wp_n=None, hold_n=None, attrs=None):
+    resources = []
+
+    io_all = []
+    if attrs is not None:
+        io_all.append(attrs)
+    io_all.append(Subsignal("cs_n", Pins(cs_n, dir="o")))
+    io_all.append(Subsignal("clk",  Pins(clk,  dir="o")))
+
+    io_1x = list(io_all)
+    io_1x.append(Subsignal("mosi", Pins(mosi, dir="o")))
+    io_1x.append(Subsignal("miso", Pins(miso, dir="i")))
+    if wp_n is not None and hold_n is not None:
+        # Tristate these pins by default, and rely on a pullup on the board or within the flash.
+        # An alternative would be to define them as outputs with reset value of 1, but that's
+        # not currently possible in nMigen.
+        io_1x.append(Subsignal("wp_n",   Pins(wp_n, dir="oe")))
+        io_1x.append(Subsignal("hold_n", Pins(hold_n, dir="oe")))
+    resources.append(Resource("spiflash", number, *io_1x))
+
+    io_2x = list(io_all)
+    io_2x.append(Subsignal("dq", Pins(" ".join([mosi, miso]), dir="io")))
+    resources.append(Resource("spiflash2x", number, *io_2x))
+
+    if wp_n is not None and hold_n is not None:
+        io_4x = list(io_all)
+        io_4x.append(Subsignal("dq", Pins(" ".join([mosi, miso, wp_n, hold_n]), dir="io")))
+        resources.append(Resource("spiflash4x", number, *io_4x))
+
+    return resources