chardev: add serial chardev support to chardev-add (qmp)

Similar to file, except that no separate in/out files are supported
because it's pointless for direct device access.  Also the special
tty ioctl hooks (pass through linespeed settings etc) are activated
on Unix.

Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>

qapi-schema.json

@@ -3031,6 +3031,22 @@
 { 'type': 'ChardevFile', 'data': { '*in' : 'str',
                                    'out' : 'str' } }
 
+##
+# @ChardevPort:
+#
+# Configuration info for device chardevs.
+#
+# @device: The name of the special file for the device,
+#          i.e. /dev/ttyS0 on Unix or COM1: on Windows
+# @type: What kind of device this is.
+#
+# Since: 1.4
+##
+{ 'enum': 'ChardevPortKind', 'data': [ 'serial' ] }
+
+{ 'type': 'ChardevPort', 'data': { 'device' : 'str',
+                                   'type'   : 'ChardevPortKind'} }
+
 ##
 # @ChardevBackend:
 #
@@ -3041,6 +3057,7 @@
 { 'type': 'ChardevDummy', 'data': { } }
 
 { 'union': 'ChardevBackend', 'data': { 'file' : 'ChardevFile',
+                                       'port' : 'ChardevPort',
                                        'null' : 'ChardevDummy' } }
 
 ##

qemu-char.c

@@ -1230,21 +1230,27 @@ static void qemu_chr_close_tty(CharDriverState *chr)
     }
 }
 
+static CharDriverState *qemu_chr_open_tty_fd(int fd)
+{
+    CharDriverState *chr;
+
+    tty_serial_init(fd, 115200, 'N', 8, 1);
+    chr = qemu_chr_open_fd(fd, fd);
+    chr->chr_ioctl = tty_serial_ioctl;
+    chr->chr_close = qemu_chr_close_tty;
+    return chr;
+}
+
 static CharDriverState *qemu_chr_open_tty(QemuOpts *opts)
 {
     const char *filename = qemu_opt_get(opts, "path");
-    CharDriverState *chr;
     int fd;
 
     TFR(fd = qemu_open(filename, O_RDWR | O_NONBLOCK));
     if (fd < 0) {
         return NULL;
     }
-    tty_serial_init(fd, 115200, 'N', 8, 1);
-    chr = qemu_chr_open_fd(fd, fd);
-    chr->chr_ioctl = tty_serial_ioctl;
-    chr->chr_close = qemu_chr_close_tty;
-    return chr;
+    return qemu_chr_open_tty_fd(fd);
 }
 #endif /* __linux__ || __sun__ */
 
@@ -1666,9 +1672,8 @@ static int win_chr_poll(void *opaque)
     return 0;
 }
 
-static CharDriverState *qemu_chr_open_win(QemuOpts *opts)
+static CharDriverState *qemu_chr_open_win_path(const char *filename)
 {
-    const char *filename = qemu_opt_get(opts, "path");
     CharDriverState *chr;
     WinCharState *s;
 
@@ -1687,6 +1692,11 @@ static CharDriverState *qemu_chr_open_win(QemuOpts *opts)
     return chr;
 }
 
+static CharDriverState *qemu_chr_open_win(QemuOpts *opts)
+{
+    return qemu_chr_open_win_path(qemu_opt_get(opts, "path"));
+}
+
 static int win_chr_pipe_poll(void *opaque)
 {
     CharDriverState *chr = opaque;
@@ -2765,6 +2775,7 @@ static const struct {
 #endif
 #ifdef HAVE_CHARDEV_TTY
     { .name = "tty",       .open = qemu_chr_open_tty },
+    { .name = "serial",    .open = qemu_chr_open_tty },
     { .name = "pty",       .open = qemu_chr_open_pty },
 #endif
 #ifdef HAVE_CHARDEV_PARPORT
@@ -3031,6 +3042,17 @@ static CharDriverState *qmp_chardev_open_file(ChardevFile *file, Error **errp)
     return qemu_chr_open_win_file(out);
 }
 
+static CharDriverState *qmp_chardev_open_port(ChardevPort *port, Error **errp)
+{
+    switch (port->type) {
+    case CHARDEV_PORT_KIND_SERIAL:
+        return qemu_chr_open_win_path(port->device);
+    default:
+        error_setg(errp, "unknown chardev port (%d)", port->type);
+        return NULL;
+    }
+}
+
 #else /* WIN32 */
 
 static int qmp_chardev_open_file_source(char *src, int flags,
@@ -3067,6 +3089,27 @@ static CharDriverState *qmp_chardev_open_file(ChardevFile *file, Error **errp)
     return qemu_chr_open_fd(in, out);
 }
 
+static CharDriverState *qmp_chardev_open_port(ChardevPort *port, Error **errp)
+{
+    int flags, fd;
+
+    switch (port->type) {
+#ifdef HAVE_CHARDEV_TTY
+    case CHARDEV_PORT_KIND_SERIAL:
+        flags = O_RDWR;
+        fd = qmp_chardev_open_file_source(port->device, flags, errp);
+        if (error_is_set(errp)) {
+            return NULL;
+        }
+        socket_set_nonblock(fd);
+        return qemu_chr_open_tty_fd(fd);
+#endif
+    default:
+        error_setg(errp, "unknown chardev port (%d)", port->type);
+        return NULL;
+    }
+}
+
 #endif /* WIN32 */
 
 ChardevReturn *qmp_chardev_add(const char *id, ChardevBackend *backend,
@@ -3086,6 +3129,9 @@ ChardevReturn *qmp_chardev_add(const char *id, ChardevBackend *backend,
     case CHARDEV_BACKEND_KIND_FILE:
         chr = qmp_chardev_open_file(backend->file, errp);
         break;
+    case CHARDEV_BACKEND_KIND_PORT:
+        chr = qmp_chardev_open_port(backend->port, errp);
+        break;
     case CHARDEV_BACKEND_KIND_NULL:
         chr = qemu_chr_open_null(NULL);
         break;

qemu-options.hx

@@ -1742,6 +1742,7 @@ DEF("chardev", HAS_ARG, QEMU_OPTION_chardev,
 #endif
 #if defined(__linux__) || defined(__sun__) || defined(__FreeBSD__) \
         || defined(__NetBSD__) || defined(__OpenBSD__) || defined(__DragonFly__)
+    "-chardev serial,id=id,path=path[,mux=on|off]\n"
     "-chardev tty,id=id,path=path[,mux=on|off]\n"
 #endif
 #if defined(__linux__) || defined(__FreeBSD__) || defined(__DragonFly__)
@@ -1910,8 +1911,8 @@ take any options.
 
 Send traffic from the guest to a serial device on the host.
 
-@option{serial} is
-only available on Windows hosts.
+On Unix hosts serial will actually accept any tty device,
+not only serial lines.
 
 @option{path} specifies the name of the serial device to open.
 
@@ -1937,10 +1938,8 @@ Connect to a local BrlAPI server. @option{braille} does not take any options.
 
 @item -chardev tty ,id=@var{id} ,path=@var{path}
 
-Connect to a local tty device.
-
 @option{tty} is only available on Linux, Sun, FreeBSD, NetBSD, OpenBSD and
-DragonFlyBSD hosts.
+DragonFlyBSD hosts.  It is an alias for -serial.
 
 @option{path} specifies the path to the tty. @option{path} is required.