arm: async uart writes & fixes

arm/uart.h

@@ -3,20 +3,37 @@
 #include <span>
 #include <string_view>
 
-#include "xuartlite.h"
-
-extern XUartLite* uart0;
+#include "async.h"
+#include "buffer.h"
 
 void InitUarts();
 
-// blocking
-void UartSend(std::span<const std::byte> data);
-inline void UartSend(std::string_view s) {
-    return UartSend(std::as_bytes(std::span{s.data(), s.size()}));
+async::task<buffer> UartRead(int size);
+async::task<> UartWrite(std::span<const std::byte> data);
+inline async::task<> UartWrite(std::string_view s) {
+    co_await UartWrite(std::as_bytes(std::span{s.data(), s.size()}));
 }
-void UartSendCrash(std::span<const std::byte> data);
-inline void UartSendCrash(std::string_view s) {
-    return UartSendCrash(std::as_bytes(std::span{s.data(), s.size()}));
+
+// block until the provided buffer is full
+void UartReadBlocking(std::span<std::byte> data);
+inline uint8_t UartReadByteBlocking() {
+    std::byte byte;
+    UartReadBlocking(std::span{&byte, 1});
+    return static_cast<uint8_t>(byte);
+}
+
+// send and poll the uart until transmitted
+void UartWriteCrash(std::span<const std::byte> data);
+inline void UartWriteCrash(std::string_view s) {
+    return UartWriteCrash(std::as_bytes(std::span{s.data(), s.size()}));
+}
+
+// block until room is available in tx fifo, then send
+void UartWriteBlocking(std::span<const std::byte> data);
+inline void UartWriteBlocking(std::string_view s) {
+    return UartWriteBlocking(std::as_bytes(std::span{s.data(), s.size()}));
 }
 
 void HandleUartTxFromIsr(void*, unsigned int transmitted);
+void HandleUartRxFromIsr(void*, unsigned int);
+void HandleUartIsr();