Use Linux custom baud rate selection based on struct termios2.

device/serial/serial_io_handler_posix.cc

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "device/serial/serial_io_handler_posix.h"
 
 #include <sys/ioctl.h>
 #include <termios.h>
 
 #include "base/posix/eintr_wrapper.h"
 
 #if defined(OS_LINUX)
 #include <linux/serial.h>
 #if defined(OS_CHROMEOS)
 #include "base/bind.h"
 #include "base/sys_info.h"
 #include "chromeos/dbus/dbus_thread_manager.h"
 #include "chromeos/dbus/permission_broker_client.h"
 #endif  // defined(OS_CHROMEOS)
+
+// The definition of struct termios2 is copied from asm-generic/termbits.h
+// because including that header directly conflicts with termios.h.
+extern "C" {
+struct termios2 {
+  tcflag_t c_iflag;  // input mode flags
+  tcflag_t c_oflag;  // output mode flags
+  tcflag_t c_cflag;  // control mode flags
+  tcflag_t c_lflag;  // local mode flags
+  cc_t c_line;       // line discipline
+  cc_t c_cc[19];     // control characters
+  speed_t c_ispeed;  // input speed
+  speed_t c_ospeed;  // output speed
+};
+}
+
 #endif  // defined(OS_LINUX)
 
 namespace {
 
 // Convert an integral bit rate to a nominal one. Returns |true|
 // if the conversion was successful and |false| otherwise.
 bool BitrateToSpeedConstant(int bitrate, speed_t* speed) {
 #define BITRATE_TO_SPEED_CASE(x) \
   case x:                        \
     *speed = B##x;               \
     return true;
   switch (bitrate) {
     BITRATE_TO_SPEED_CASE(0)
     BITRATE_TO_SPEED_CASE(50)
     BITRATE_TO_SPEED_CASE(75)
     BITRATE_TO_SPEED_CASE(110)
     BITRATE_TO_SPEED_CASE(134)
     BITRATE_TO_SPEED_CASE(150)
     BITRATE_TO_SPEED_CASE(200)
     BITRATE_TO_SPEED_CASE(300)
     BITRATE_TO_SPEED_CASE(600)
     BITRATE_TO_SPEED_CASE(1200)
     BITRATE_TO_SPEED_CASE(1800)
     BITRATE_TO_SPEED_CASE(2400)
     BITRATE_TO_SPEED_CASE(4800)
     BITRATE_TO_SPEED_CASE(9600)
     BITRATE_TO_SPEED_CASE(19200)
     BITRATE_TO_SPEED_CASE(38400)
-#if defined(OS_POSIX) && !defined(OS_MACOSX)
+#if !defined(OS_MACOSX)
     BITRATE_TO_SPEED_CASE(57600)
     BITRATE_TO_SPEED_CASE(115200)
     BITRATE_TO_SPEED_CASE(230400)
     BITRATE_TO_SPEED_CASE(460800)
     BITRATE_TO_SPEED_CASE(576000)
     BITRATE_TO_SPEED_CASE(921600)
 #endif
     default:
       return false;
   }
@@ skipping 17 matching lines @@
     SPEED_TO_BITRATE_CASE(200)
     SPEED_TO_BITRATE_CASE(300)
     SPEED_TO_BITRATE_CASE(600)
     SPEED_TO_BITRATE_CASE(1200)
     SPEED_TO_BITRATE_CASE(1800)
     SPEED_TO_BITRATE_CASE(2400)
     SPEED_TO_BITRATE_CASE(4800)
     SPEED_TO_BITRATE_CASE(9600)
     SPEED_TO_BITRATE_CASE(19200)
     SPEED_TO_BITRATE_CASE(38400)
-#if defined(OS_POSIX) && !defined(OS_MACOSX)
+#if !defined(OS_MACOSX)
     SPEED_TO_BITRATE_CASE(57600)
     SPEED_TO_BITRATE_CASE(115200)
     SPEED_TO_BITRATE_CASE(230400)
     SPEED_TO_BITRATE_CASE(460800)
     SPEED_TO_BITRATE_CASE(576000)
     SPEED_TO_BITRATE_CASE(921600)
 #endif
     default:
       return false;
   }
 #undef SPEED_TO_BITRATE_CASE
 }
 
 bool SetCustomBitrate(base::PlatformFile file,
                       struct termios* config,
                       int bitrate) {
 #if defined(OS_LINUX)
-  struct serial_struct serial;
-  if (ioctl(file, TIOCGSERIAL, &serial) < 0) {
+  struct termios2 tio;
+  if (ioctl(file, TCGETS2, &tio) < 0) {
+    VPLOG(1) << "Failed to get parameters to set custom bitrate";
     return false;
   }
-  serial.flags = (serial.flags & ~ASYNC_SPD_MASK) | ASYNC_SPD_CUST;
-  serial.custom_divisor = serial.baud_base / bitrate;
-  if (serial.custom_divisor < 1) {
-    serial.custom_divisor = 1;
+  tio.c_cflag &= ~CBAUD;
+  tio.c_cflag |= CBAUDEX;
+  tio.c_ispeed = bitrate;
+  tio.c_ospeed = bitrate;
+  if (ioctl(file, TCSETS2, &tio) < 0) {
+    VPLOG(1) << "Failed to set custom bitrate";
+    return false;
   }
-  cfsetispeed(config, B38400);
-  cfsetospeed(config, B38400);
-  return ioctl(file, TIOCSSERIAL, &serial) >= 0;
+  return true;
 #elif defined(OS_MACOSX)
   speed_t speed = static_cast<speed_t>(bitrate);
   cfsetispeed(config, speed);
   cfsetospeed(config, speed);
   return true;
 #else
   return false;
 #endif
 }
 
@@ skipping 326 matching lines @@
       (config.c_cflag & CSTOPB) ? serial::STOP_BITS_TWO : serial::STOP_BITS_ONE;
   info->cts_flow_control = (config.c_cflag & CRTSCTS) != 0;
   return info.Pass();
 }
 
 std::string SerialIoHandler::MaybeFixUpPortName(const std::string& port_name) {
   return port_name;
 }
 
 }  // namespace device