Improve soc.svd output for eventmanager events

Right now no data is created for which bit means what in
the soc.svd file. Attempt to extend event manager finalization
to use "fields" instead of bit positions, so that the SVD
file can auto-generate the events correctly.

litex/soc/interconnect/csr_eventmanager.py

@@ -142,18 +142,22 @@ class EventManager(Module, AutoCSR):
         sources_u = [v for k, v in xdir(self, True) if isinstance(v, _EventSource)]
         sources = sorted(sources_u, key=lambda x: x.duid)
         n = len(sources)
-        self.status = CSR(n)
+
-        self.pending = CSR(n)
+        fields = []
-        self.enable = CSRStorage(n)
+        for i, source in enumerate(sources):
+            fields += [CSRField(source.name, size=1, description="Mask bit for {}".format(str(source.name)))]
+        self.status = CSRStatus(n, fields=fields)
+        self.pending = CSRStatus(n, fields=fields)
+        self.enable = CSRStorage(n, fields=fields)
 
         for i, source in enumerate(sources):
             self.comb += [
-                self.status.w[i].eq(source.status),
+                getattr(self.status.fields, source.name).eq(source.status),
-                If(self.pending.re & self.pending.r[i], source.clear.eq(1)),
+                getattr(self.pending.fields, source.name).eq(source.pending),
-                self.pending.w[i].eq(source.pending)
+                If(self.pending.re & getattr(self.pending.fields, source.name), source.clear.eq(1)),
             ]
 
-        irqs = [self.pending.w[i] & self.enable.storage[i] for i in range(n)]
+        irqs = [self.pending.status[i] & self.enable.storage[i] for i in range(n)]
         self.comb += self.irq.eq(reduce(or_, irqs))
 
     def __setattr__(self, name, value):