From 85f12c75f1aeb7ef6140d028b941d5dde4bed4ba Mon Sep 17 00:00:00 2001
From: Byron Lathi <bslathi19@gmail.com>
Date: Fri, 21 Jul 2023 22:10:39 -0700
Subject: [PATCH] Start spi controller and tb

---
 .gitignore                                    |  1 +
 .vscode/settings.json                         |  5 --
 hw/efinix_fpga/simulation/Makefile            |  5 +-
 .../simulation/spi_controller_tb.sv           | 69 +++++++++++++++
 hw/efinix_fpga/spi_controller.sv              | 84 +++++++++++++++++++
 5 files changed, 158 insertions(+), 6 deletions(-)
 create mode 100644 .gitignore
 delete mode 100644 .vscode/settings.json
 create mode 100644 hw/efinix_fpga/simulation/spi_controller_tb.sv
 create mode 100644 hw/efinix_fpga/spi_controller.sv

diff --git a/.gitignore b/.gitignore
new file mode 100644
index 0000000..722d5e7
--- /dev/null
+++ b/.gitignore
@@ -0,0 +1 @@
+.vscode
diff --git a/.vscode/settings.json b/.vscode/settings.json
deleted file mode 100644
index 0cbf8a7..0000000
--- a/.vscode/settings.json
+++ /dev/null
@@ -1,5 +0,0 @@
-{
-    "files.associations": {
-        "conio.h": "c"
-    }
-}
\ No newline at end of file
diff --git a/hw/efinix_fpga/simulation/Makefile b/hw/efinix_fpga/simulation/Makefile
index 2befbaf..ebaffce 100644
--- a/hw/efinix_fpga/simulation/Makefile
+++ b/hw/efinix_fpga/simulation/Makefile
@@ -1,4 +1,4 @@
-TARGETS= timer interrupt_controller
+TARGETS= timer interrupt_controller spi_controller
 TB=$(patsubst %, %_tb.sv, $(TARGETS))
 
 all: $(TARGETS)
@@ -6,6 +6,9 @@ all: $(TARGETS)
 timer: timer_tb.sv
 	iverilog -g2005-sv -s sim -o $@ $@_tb.sv ../$@.sv
 
+spi_controller: spi_controller_tb.sv
+	iverilog -g2005-sv -s sim -o $@ $@_tb.sv ../$@.sv
+
 interrupt_controller: interrupt_controller_tb.sv
 	iverilog -g2005-sv -s sim -o $@ $@_tb.sv ../$@.sv
 
diff --git a/hw/efinix_fpga/simulation/spi_controller_tb.sv b/hw/efinix_fpga/simulation/spi_controller_tb.sv
new file mode 100644
index 0000000..37c1ae3
--- /dev/null
+++ b/hw/efinix_fpga/simulation/spi_controller_tb.sv
@@ -0,0 +1,69 @@
+module sim();
+
+timeunit 10ns;
+timeprecision 1ns;
+
+logic clk_50;
+
+logic i_clk;
+logic i_rst;
+
+logic i_cs;
+logic i_rwb;
+logic [1:0] i_addr;
+logic [7:0] i_data;
+logic [7:0] o_data;
+
+logic o_spi_cs;
+logic o_spi_clk;
+logic o_spi_mosi;
+logic i_spi_miso;
+
+spi_controller dut(.*);
+
+always #1 clk_50 = clk_50 === 1'b0;
+always #100 i_clk = i_clk === 1'b0;
+
+task write_reg(input logic [2:0] _addr, input logic [7:0] _data);
+    @(negedge i_clk);
+    i_cs <= '1;
+    i_addr <= _addr;
+    i_rwb <= '0;
+    i_data <= '1;
+    @(posedge i_clk);
+    i_data <= _data;
+    @(negedge i_clk);
+    i_cs <= '0;
+    i_rwb <= '1;
+endtask
+
+task read_reg(input logic [2:0] _addr, output logic [7:0] _data);
+    @(negedge i_clk);
+    i_cs <= '1;
+    i_addr <= _addr;
+    i_rwb <= '1;
+    i_data <= '1;
+    @(posedge i_clk);
+    _data <= o_data;
+    @(negedge i_clk);
+    i_cs <= '0;
+    i_rwb <= '1;
+endtask
+
+initial
+begin
+    $dumpfile("spi_controller.vcd");
+    $dumpvars(0,sim);
+end
+
+initial begin
+    i_rst <= '1;
+    repeat(5) @(posedge i_clk);
+    i_rst <= '0;
+
+    repeat(5) @(posedge i_clk);
+
+    $finish();
+end
+
+endmodule
\ No newline at end of file
diff --git a/hw/efinix_fpga/spi_controller.sv b/hw/efinix_fpga/spi_controller.sv
new file mode 100644
index 0000000..9b806f7
--- /dev/null
+++ b/hw/efinix_fpga/spi_controller.sv
@@ -0,0 +1,84 @@
+module spi_controller(
+    input i_clk,
+    input i_rst,
+
+    input i_cs,
+    input i_rwb,
+    input [1:0] i_addr,
+    input [7:0] i_data,
+    output logic [7:0] o_data,
+
+    output o_spi_cs,
+    output o_spi_clk,
+    output o_spi_mosi,
+    input i_spi_miso
+);
+
+
+// We need a speed register
+// an input data register
+// and an output data register
+// and then a control register for cs
+
+logic [7:0] r_baud_rate;
+logic [7:0] r_input_data;
+logic [7:0] r_output_data;
+logic [7:0] r_control;
+
+logic [8:0] r_clock_counter;
+
+logic active;
+logic spi_clk;
+
+logic r_spi_mosi;
+
+always @(posedge i_clk) begin
+    if (i_rst) begin
+        r_baud_rate <= 8'h10;
+        r_input_data <= '0;
+        r_output_data <= '0;
+        r_control <= '0;
+        r_clock_counter <= '0;
+        spi_clk <= '0;
+    end else begin
+        if (~i_rwb & i_cs) begin
+            unique case (i_addr)
+                0: r_baud_rate <= i_data;
+                1:;
+                2: begin 
+                    r_output_data <= i_data;
+                    active <= '1;
+                end
+                3: r_control <= i_data;
+            endcase
+        end
+
+        if (active) begin
+            r_spi_mosi <= r_output_data[0];
+            r_clock_counter <= r_clock_counter + 9'b1;
+            if (r_clock_counter >= r_baud_rate) begin
+                r_clock_counter <= '0;
+                spi_clk <= ~spi_clk;
+                if (spi_clk == '0) begin
+                    r_output_data <= r_output_data >> 1;
+                end
+                if (spi_clk == '1) begin
+                    r_input_data <= {r_input_data[7:1], i_spi_miso};
+                end
+            end
+
+        end
+    end
+end
+
+always_comb begin
+    unique case (i_addr)
+        0: o_data = r_baud_rate;
+        1: o_data = r_input_data;
+        2:;
+        3: o_data = r_control;
+    endcase
+end
+
+
+endmodule
\ No newline at end of file