1 files changed, 149 insertions, 0 deletions
diff --git a/pw_stream_uart_linux/stream.cc b/pw_stream_uart_linux/stream.cc
new file mode 100644
index 000000000..7bb7e7f15
--- /dev/null
+++ b/pw_stream_uart_linux/stream.cc
@@ -0,0 +1,149 @@
+// Copyright 2023 The Pigweed Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License"); you may not
+// use this file except in compliance with the License. You may obtain a copy of
+// the License at
+//
+//     https://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+// WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+// License for the specific language governing permissions and limitations under
+// the License.
+
+#include "pw_stream_uart_linux/stream.h"
+
+#include <fcntl.h>
+#include <termios.h>
+#include <unistd.h>
+
+#include <cerrno>
+#include <cinttypes>
+
+#include "pw_log/log.h"
+
+namespace pw::stream {
+
+Result<speed_t> BaudRateToSpeed(uint32_t baud_rate) {
+  switch (baud_rate) {
+    case 9600:
+      return B9600;
+    case 19200:
+      return B19200;
+    case 38400:
+      return B38400;
+    case 57600:
+      return B57600;
+    case 115200:
+      return B115200;
+    case 230400:
+      return B230400;
+    case 460800:
+      return B460800;
+    case 500000:
+      return B500000;
+    case 576000:
+      return B576000;
+    case 921600:
+      return B921600;
+    case 1000000:
+      return B1000000;
+    case 1152000:
+      return B1152000;
+    case 1500000:
+      return B1500000;
+    case 2000000:
+      return B2000000;
+    case 2500000:
+      return B2500000;
+    case 3000000:
+      return B3000000;
+    case 3500000:
+      return B3500000;
+    case 4000000:
+      return B4000000;
+    default:
+      return Status::InvalidArgument();
+  }
+}
+
+Status UartStreamLinux::Open(const char* path, uint32_t baud_rate) {
+  const auto speed_result = BaudRateToSpeed(baud_rate);
+  if (!speed_result.ok()) {
+    PW_LOG_ERROR("Unsupported baud rate: %" PRIu32, baud_rate);
+    return speed_result.status();
+  }
+  speed_t speed = speed_result.value();
+
+  if (fd_ != kInvalidFd) {
+    PW_LOG_ERROR("UART device already open");
+    return Status::FailedPrecondition();
+  }
+
+  fd_ = open(path, O_RDWR);
+  if (fd_ < 0) {
+    PW_LOG_ERROR(
+        "Failed to open UART device '%s', %s", path, std::strerror(errno));
+    return Status::Unknown();
+  }
+
+  struct termios tty;
+  int result = tcgetattr(fd_, &tty);
+  if (result < 0) {
+    PW_LOG_ERROR("Failed to get TTY attributes for '%s', %s",
+                 path,
+                 std::strerror(errno));
+    return Status::Unknown();
+  }
+
+  cfmakeraw(&tty);
+  result = cfsetspeed(&tty, speed);
+  if (result < 0) {
+    PW_LOG_ERROR(
+        "Failed to set TTY speed for '%s', %s", path, std::strerror(errno));
+    return Status::Unknown();
+  }
+
+  result = tcsetattr(fd_, TCSANOW, &tty);
+  if (result < 0) {
+    PW_LOG_ERROR("Failed to set TTY attributes for '%s', %s",
+                 path,
+                 std::strerror(errno));
+    return Status::Unknown();
+  }
+
+  return OkStatus();
+}
+
+void UartStreamLinux::Close() {
+  if (fd_ != kInvalidFd) {
+    close(fd_);
+    fd_ = kInvalidFd;
+  }
+}
+
+Status UartStreamLinux::DoWrite(ConstByteSpan data) {
+  const size_t size = data.size_bytes();
+  size_t written = 0;
+  while (written < size) {
+    int bytes = write(fd_, &data[written], size - written);
+    if (bytes < 0) {
+      PW_LOG_ERROR("Failed to write to UART, %s", std::strerror(errno));
+      return Status::Unknown();
+    }
+    written += bytes;
+  }
+  return OkStatus();
+}
+
+StatusWithSize UartStreamLinux::DoRead(ByteSpan dest) {
+  int bytes = read(fd_, &dest[0], dest.size_bytes());
+  if (bytes < 0) {
+    PW_LOG_ERROR("Failed to read from UART, %s", std::strerror(errno));
+    return StatusWithSize::Unknown();
+  }
+  return StatusWithSize(bytes);
+}
+
+}  // namespace pw::stream