mbv: add uart echo app

mbv/Makefile

@@ -14,6 +14,10 @@ wozmon:  ## Build the wozmon app in docker
 timer:  ## Build the timer app in docker
 	docker build -o . --target export --build-arg TARGET=timer.bin .
 
+.PHONY: uart
+uart:  ## Build the uart app in docker
+	docker build -o . --target export --build-arg TARGET=uart.bin .
+
 .PHONY: dev-image
 dev-image:
 	docker build -t mbv-dev --target dev .

mbv/apps/uart/uart.cc

@@ -0,0 +1,87 @@
+#include <cstdint>
+
+#include "intc.h"
+#include "interrupts.h"
+#include "pol0.h"
+#include "xuartlite.h"
+
+extern "C" {
+void BiosWozmon();
+}
+
+namespace {
+
+struct Gpio {
+    volatile uint32_t data;
+};
+
+Gpio* leds = reinterpret_cast<Gpio*>(GPIO0_BASE);
+
+XUartLite uart0_inst;
+XUartLite_Config uart0_config = {
+    .DeviceId = 0,
+    .RegBaseAddr = UART0_BASE,
+    .BaudRate = 115200,
+    .UseParity = false,
+    .DataBits = 8,
+};
+
+XUartLite* uart0 = &uart0_inst;
+
+volatile int incoming = 0;
+
+void HandleUartRxFromIsr(void*, unsigned int) {
+    incoming += 1;
+}
+
+void HandleUartTxFromIsr(void*, unsigned int) {
+}
+
+void Uart0Isr() {
+    XUartLite_InterruptHandler(uart0);
+}
+
+void InitUarts() {
+    XUartLite_CfgInitialize(uart0, &uart0_config, uart0_config.RegBaseAddr);
+
+    XUartLite_SetSendHandler(uart0, HandleUartTxFromIsr, nullptr);
+    XUartLite_SetRecvHandler(uart0, HandleUartRxFromIsr, nullptr);
+    XUartLite_EnableInterrupt(uart0);
+
+    SetIsr(UART0_IRQN, Uart0Isr);
+    SetIrqEnabled(UART0_IRQN, true);
+}
+
+}
+
+int main() {
+    leds->data = 0xa0;
+
+    InitUarts();
+    EnableInterrupts();
+    SetExternalInterruptHandler(InterruptHandler);
+    EnableExternalInterrupts();
+
+    int counter = 0;
+
+    uint8_t c;
+    while (XUartLite_Recv(uart0, &c, 1) > 0) {
+        XUartLite_Send(uart0, &c, 1);
+        while (XUartLite_IsSending(uart0)) {}
+    }
+    leds->data = 0xa1;
+    while (1) {
+        // should disable interrupts around this
+        if (incoming > 0) {
+            counter += 1;
+            leds->data = counter;
+            XUartLite_Send(uart0, &c, 1);
+            while (XUartLite_IsSending(uart0)) {}
+            while (XUartLite_Recv(uart0, &c, 1) > 0) {
+                XUartLite_Send(uart0, &c, 1);
+                while (XUartLite_IsSending(uart0)) {}
+            }
+            incoming -= 1;
+        }
+    }
+}

mbv/configure

@@ -277,6 +277,7 @@ all = [
         app_image("helloworld"),
         app_image("wozmon"),
         app_image("timer"),
+        app_image("uart"),
 ]