From 64700dec65d6217d88b8f869dcf1a36cc365f94d Mon Sep 17 00:00:00 2001
From: YRabbit <rabbit@yrabbit.cyou>
Date: Tue, 21 Oct 2025 12:36:06 +1000
Subject: [PATCH] Gowin. Disable unsupported BSRAM mode in GW5A

All supported (and planned to be supported) GW5A series chips do not
support the 2: Read-before-Write write mode.

Here, we prohibit the generation of BSRAM with this mode.

Signed-off-by: YRabbit <rabbit@yrabbit.cyou>
---
 techlibs/gowin/Makefile.inc   |  1 +
 techlibs/gowin/brams_gw5a.txt | 69 +++++++++++++++++++++++++++++++++++
 techlibs/gowin/synth_gowin.cc |  2 +-
 3 files changed, 71 insertions(+), 1 deletion(-)
 create mode 100644 techlibs/gowin/brams_gw5a.txt

diff --git a/techlibs/gowin/Makefile.inc b/techlibs/gowin/Makefile.inc
index df1b79317..08893e73f 100644
--- a/techlibs/gowin/Makefile.inc
+++ b/techlibs/gowin/Makefile.inc
@@ -10,5 +10,6 @@ $(eval $(call add_share_file,share/gowin,techlibs/gowin/arith_map.v))
 $(eval $(call add_share_file,share/gowin,techlibs/gowin/brams_map.v))
 $(eval $(call add_share_file,share/gowin,techlibs/gowin/brams_map_gw5a.v))
 $(eval $(call add_share_file,share/gowin,techlibs/gowin/brams.txt))
+$(eval $(call add_share_file,share/gowin,techlibs/gowin/brams_gw5a.txt))
 $(eval $(call add_share_file,share/gowin,techlibs/gowin/lutrams_map.v))
 $(eval $(call add_share_file,share/gowin,techlibs/gowin/lutrams.txt))
diff --git a/techlibs/gowin/brams_gw5a.txt b/techlibs/gowin/brams_gw5a.txt
new file mode 100644
index 000000000..2747ea451
--- /dev/null
+++ b/techlibs/gowin/brams_gw5a.txt
@@ -0,0 +1,69 @@
+ram block $__GOWIN_SP_ {
+	abits 14;
+	widths 1 2 4 9 18 36 per_port;
+	cost 128;
+	init no_undef;
+	port srsw "A" {
+		clock posedge;
+		clken;
+		option "RESET_MODE" "SYNC" {
+			rdsrst zero ungated;
+		}
+		option "RESET_MODE" "ASYNC" {
+			rdarst zero;
+		}
+		rdinit zero;
+		portoption "WRITE_MODE" 0 {
+			rdwr no_change;
+		}
+		portoption "WRITE_MODE" 1 {
+			rdwr new;
+		}
+	}
+}
+
+ram block $__GOWIN_DP_ {
+	abits 14;
+	widths 1 2 4 9 18 per_port;
+	cost 128;
+	init no_undef;
+	port srsw "A" "B" {
+		clock posedge;
+		clken;
+		option "RESET_MODE" "SYNC" {
+			rdsrst zero ungated;
+		}
+		option "RESET_MODE" "ASYNC" {
+			rdarst zero;
+		}
+		rdinit zero;
+		portoption "WRITE_MODE" 0 {
+			rdwr no_change;
+		}
+		portoption "WRITE_MODE" 1 {
+			rdwr new;
+		}
+	}
+}
+
+ram block $__GOWIN_SDP_ {
+	abits 14;
+	widths 1 2 4 9 18 36 per_port;
+	cost 128;
+	init no_undef;
+	port sr "R" {
+		clock posedge;
+		clken;
+		option "RESET_MODE" "SYNC" {
+			rdsrst zero ungated;
+		}
+		option "RESET_MODE" "ASYNC" {
+			rdarst zero;
+		}
+		rdinit zero;
+	}
+	port sw "W" {
+		clock posedge;
+		clken;
+	}
+}
diff --git a/techlibs/gowin/synth_gowin.cc b/techlibs/gowin/synth_gowin.cc
index 1a55f9f37..4e925daab 100644
--- a/techlibs/gowin/synth_gowin.cc
+++ b/techlibs/gowin/synth_gowin.cc
@@ -263,7 +263,7 @@ struct SynthGowinPass : public ScriptPass
 				if (nolutram)
 					args += " -no-auto-distributed";
 			}
-			run("memory_libmap -lib +/gowin/lutrams.txt -lib +/gowin/brams.txt" + args, "(-no-auto-block if -nobram, -no-auto-distributed if -nolutram)");
+			run(stringf("memory_libmap -lib +/gowin/lutrams.txt -lib +/gowin/brams%s.txt", family == "gw5a" ? "_gw5a" : "") + args, "(-no-auto-block if -nobram, -no-auto-distributed if -nolutram)");
 			run(stringf("techmap -map +/gowin/lutrams_map.v -map +/gowin/brams_map%s.v", family == "gw5a" ? "_gw5a" : ""));
 		}