axi_pwm_gen: Start, Stop fix

Previously when issuing a load_config, each pwm channel
was stopped in its tracks and waited for an external sync,
if that was active, or load_config release.
The desired behaviour is to wait for the pwm channels to finish
their events from the current period, before a new aligned start.
Also, the first positive edge of each pulse was initiated only
in the second pwm channel period.
This niche behaviours have not affected any functionality in the
long term alignments for current setups.

Signed-off-by: AndreiGrozav <andrei.grozav@analog.com>

library/axi_pwm_gen/axi_pwm_gen_1.v

@@ -47,7 +47,7 @@ module axi_pwm_gen_1 #(
   input               load_config,
   input               sync,
 
-  output  reg         pulse,
+  output              pulse,
   output              pulse_armed
 );
 
@@ -59,6 +59,8 @@ module axi_pwm_gen_1 #(
   reg     [31:0]               pulse_period_d = PULSE_PERIOD;
   reg     [31:0]               pulse_width_d = PULSE_WIDTH;
   reg                          phase_align_armed = 1'b1;
+  reg                          pulse_i = 1'b0;
+  reg                          busy = 1'b0;
 
   // internal wires
 
@@ -107,7 +109,19 @@ module axi_pwm_gen_1 #(
     end
   end
 
-  assign phase_align = phase_align_armed & sync;
+  always @(posedge clk) begin
+    if (rstn == 1'b0) begin
+      busy <= 1'b0;
+    end else begin
+      if (end_of_period) begin
+        busy <= 1'b0;
+      end else if ( ~(phase_align_armed & sync)) begin
+        busy <= 1'b1;
+      end
+    end
+  end
+
+  assign phase_align = phase_align_armed & sync & busy;
 
   // a free running counter
 
@@ -127,13 +141,14 @@ module axi_pwm_gen_1 #(
   // generate pulse with a specified width
 
   always @ (posedge clk) begin
-    if ((rstn == 1'b0) || (phase_align == 1'b1) || (end_of_pulse == 1'b1)) begin
-      pulse <= 1'b0;
-    end else if (end_of_period == 1'b1 && pulse_enable == 1'b1) begin
-      pulse <= 1'b1;
+    if ((rstn == 1'b0) || (end_of_pulse == 1'b1)) begin
+      pulse_i <= 1'b0;
+    end else if ((end_of_period == 1'b1 || phase_align == 1'b1) && pulse_enable == 1'b1) begin
+      pulse_i <= 1'b1;
     end
   end
 
+  assign pulse = pulse_i & !(phase_align_armed & sync);
   assign pulse_armed = phase_align_armed;
 
 endmodule