Factor out I2C resource.

Author: awygle

nmigen_boards/arty_s7.py

@@ -38,10 +38,9 @@ class _ArtyS7Platform(Xilinx7SeriesPlatform):
             attrs=Attrs(IOSTANDARD="LVCMOS33")
         ),
 
-        Resource("i2c", 0,
-            Subsignal("scl",        Pins("J14", dir="io")),
-            Subsignal("sda",        Pins("J13", dir="io")),
-            Attrs(IOSTANDARD="LVCMOS33")
+        I2CResource(0,
+            scl="J14", sda="J13",
+            attrs=Attrs(IOSTANDARD="LVCMOS33")
         ),
 
         *SPIFlashResources(0,

nmigen_boards/genesys2.py

@@ -52,10 +52,8 @@ def bank15_16_17_iostandard(self):
                  Attrs(IOSTANDARD="LVCMOS33")),
         UARTResource(0, rx="Y20", tx="Y23",
                      attrs=Attrs(IOSTANDARD="LVCMOS33")),
-        Resource("i2c", 0,
-                 Subsignal("scl", Pins("AE30", dir="io")),
-                 Subsignal("sda", Pins("AF30", dir="io")),
-                 Attrs(IOSTANDARD="LVCMOS33")),
+        I2CResource(0, scl="AE30", sda="AF30",
+                    attrs=Attrs(IOSTANDARD="LVCMOS33")),
         Resource("ddr3", 0,
                  Subsignal("rst", PinsN("AG5", dir="o"),
                            Attrs(IOSTANDARD="SSTL15")),

nmigen_boards/resources/interface.py

@@ -2,7 +2,7 @@
 
 
 __all__ = [
-    "UARTResource", "IrDAResource", "SPIResource",
+    "UARTResource", "IrDAResource", "SPIResource", "I2CResource",
     "DirectUSBResource", "ULPIResource"
 ]
 
@@ -86,6 +86,15 @@ def SPIResource(*args, cs, clk, copi, cipo, int=None, reset=None,
     return Resource.family(*args, default_name="spi", ios=io)
 
 
+def I2CResource(*args, scl, sda, conn=None, attrs=None):
+    io = []
+    io.append(Subsignal("scl", Pins(scl, dir="io", conn=conn, assert_width=1)))
+    io.append(Subsignal("sda", Pins(sda, dir="io", conn=conn, assert_width=1)))
+    if attrs is not None:
+        io.append(attrs)
+    return Resource.family(*args, default_name="i2c", ios=io)
+
+
 def DirectUSBResource(*args, d_p, d_n, pullup=None, vbus_valid=None,
     conn=None, attrs=None):