From f015d6732b35f8be8be4ea434f153e969732ac06 Mon Sep 17 00:00:00 2001
From: mwojcik <mw@m-labs.hk>
Date: Mon, 16 Aug 2021 11:51:50 +0200
Subject: [PATCH] sram: support for different burst settings on read

---
 src/gateware/aux_controller.py | 30 ++++++++++++++----------------
 1 file changed, 14 insertions(+), 16 deletions(-)

diff --git a/src/gateware/aux_controller.py b/src/gateware/aux_controller.py
index 76d6ce6..ef03c34 100644
--- a/src/gateware/aux_controller.py
+++ b/src/gateware/aux_controller.py
@@ -34,13 +34,8 @@ class SRAM(Module):
 
         ###
 
-        # probably will get removed
-        self.addr_base = CSRStorage(32)
-
         # Dout : Data received from CPU, output by SRAM <- port.dat_r
         # Din : Data driven into SRAM, written into CPU <- port.dat_w
-        # When stb assert, index shows word being read/written, dout/din holds <- will be removed
-        # data
         #
         # Cycle:
         # Then out_burst_len words are strobed out of dout
@@ -51,20 +46,17 @@ class SRAM(Module):
         self.dout = Signal(64)
         self.din = Signal(64)
 
-        # probably not correct here
-        self.sync += If(self.trigger_stb, self.trig_count.status.eq(self.trig_count.status+1))
-
         ar, aw, w, r, b = attrgetter("ar", "aw", "w", "r", "b")(bus)
 
         ### Read
         self.comb += [
-            port.adr.eq(ar.addr),
+            port.adr.eq(ar.addr), # still not sure if legal hm
             r.data.eq(port.dat_r),
-            r.ready.eq(1),
-            ar.burst.eq(axi.Burst.incr.value),
-            ar.len.eq(OUT_BURST_LEN-1), # Number of transfers in burst (0->1 transfer, 1->2 transfers...)
-            ar.size.eq(3), # Width of burst: 3 = 8 bytes = 64 bits
-            ar.cache.eq(0xf),
+            # r.ready.eq(1),
+            # ar.burst.eq(axi.Burst.incr.value),
+            # ar.len.eq(OUT_BURST_LEN-1), # Number of transfers in burst (0->1 transfer, 1->2 transfers...)
+            # ar.size.eq(3), # Width of burst: 3 = 8 bytes = 64 bits
+            # ar.cache.eq(0xf),
         ]
 
         # read control
@@ -77,6 +69,7 @@ class SRAM(Module):
         )
         read_fsm.act("READ_START",
             r.data.eq(port.dat_r),
+            r.resp.eq(axi.Response.okay.value),
             r.valid.eq(1),
             If(r.ready,
                 r.data.eq(port.dat_r), # that should be always updated, right?
@@ -96,7 +89,12 @@ class SRAM(Module):
                 ar.ready.eq(0)
             ).Else(If(r.ready & read_fsm.ongoing("READ"),
                     self.dout_index.eq(self.dout_index+1),
-                    port.adr.eq(port.adr + self.dout_index), # update address in the port
+                    If(ar.burst==axi.Burst.incr.value, 
+                        port.adr.eq(port.adr + self.dout_index)
+                    ).Else(If(ar.burst==axi.Burst.wrap.value,
+                        port.adr.eq((port.adr + self.dout_index) | ar.len)
+                    )), # update address in the port if it's incr or wrapped burst value
+                    # no port.adr update for fixed burst type
                     If(self.dout_index==ar.len, r.last.eq(1)) # and update last
                 )
             )
@@ -104,7 +102,7 @@ class SRAM(Module):
 
         ### Write
         self.comb += [
-            w.data.eq(port.dat_w),
+            port.dat_w.eq(w.data),
             port.addr.eq(aw.addr),
             w.strb.eq(0xff),
             aw.burst.eq(axi.Burst.incr.value),