From 6ffed70b59a2e679ec9dcc9086c96885d16233b0 Mon Sep 17 00:00:00 2001
From: Florent Kermarrec <florent@enjoy-digital.fr>
Date: Sun, 3 Aug 2014 12:26:41 +0200
Subject: [PATCH] uart2wishbone: disconnect rx line from shared pads when
 bridge is selected (avoid CPU crash when we communicate with the bridge)

---
 miscope/host/uart2wishbone.py |  1 +
 miscope/uart2wishbone.py      | 38 ++++++++++++++++++++++++-----------
 2 files changed, 27 insertions(+), 12 deletions(-)

diff --git a/miscope/host/uart2wishbone.py b/miscope/host/uart2wishbone.py
index 03c33a8e7..e9590866c 100644
--- a/miscope/host/uart2wishbone.py
+++ b/miscope/host/uart2wishbone.py
@@ -32,6 +32,7 @@ class Uart2Wishbone:
 			self.regs.uart2wb_sel.write(0)
 		except:
 			pass
+		self.uart.flushOutput()
 		self.uart.close()
 
 	def read(self, addr, burst_length=1):
diff --git a/miscope/uart2wishbone.py b/miscope/uart2wishbone.py
index 185232e5f..8a48ebcc8 100644
--- a/miscope/uart2wishbone.py
+++ b/miscope/uart2wishbone.py
@@ -136,18 +136,32 @@ class UARTPads:
 		self.tx = Signal()
 
 class UARTMux(Module):
-	def __init__(self, pads, nb):
-		self.sel = Signal(max=nb)
-		self.pads = [UARTPads() for i in range(nb)]
+	def __init__(self, pads):
+		self.sel = Signal(max=2)
+		self.shared_pads = UARTPads()
+		self.bridge_pads = UARTPads()
 
 	###	
-		# Route Rx pad to all modules
-		for i in range(nb):
-			self.comb += self.pads[i].rx.eq(pads.rx)
+		# Route rx pad:
+		# when sel==0, route it to shared rx and bridge rx
+		# when sel==1, route it only to bridge rx
+		self.comb += \
+			If(self.sel==0,
+				self.shared_pads.rx.eq(pads.rx),
+				self.bridge_pads.rx.eq(pads.rx)
+			).Else(
+				self.bridge_pads.rx.eq(pads.rx)
+			)
 
-		# Route only selected module to Tx pad
-		pads_tx = [self.pads[i].tx for i in range(nb)]
-		self.comb += chooser(Cat(pads_tx), self.sel, pads.tx, n=nb)
+		# Route tx:
+		# when sel==0, route shared tx to pads tx
+		# when sel==1, route bridge tx to pads tx
+		self.comb += \
+			If(self.sel==0,
+				pads.tx.eq(self.shared_pads.tx)
+			).Else(
+				pads.tx.eq(self.bridge_pads.tx)
+			)
 
 class UART2Wishbone(Module, AutoCSR):
 	WRITE_CMD = 0x01
@@ -161,9 +175,9 @@ class UART2Wishbone(Module, AutoCSR):
 
 	###
 		if share_uart:
-			self.submodules.uart_mux = UARTMux(pads, 2)
-			self.submodules.uart = UART(self.uart_mux.pads[1], clk_freq, baud)
-			self.shared_pads = self.uart_mux.pads[0]
+			self.submodules.uart_mux = UARTMux(pads)
+			self.submodules.uart = UART(self.uart_mux.bridge_pads, clk_freq, baud)
+			self.shared_pads = self.uart_mux.shared_pads
 			self.comb += self.uart_mux.sel.eq(self._sel.storage)
 		else:
 			self.submodules.uart = UART(pads, clk_freq, baud)