sandbox: Improve sandbox serial port keyboard interface

Implements the tstc() interface for the serial driver.  Multiplexing
the console between the serial port and a keyboard uses a polling
method of checking if characters are available; this means that the
serial console must be non-blocking when attempting to read
characters.

Signed-off-by: Taylor Hutt <thutt@chromium.org>
Signed-off-by: Simon Glass <sjg@chromium.org>

1 files changed, 8 insertions, 0 deletions

diff --git a/arch/sandbox/cpu/os.c b/arch/sandbox/cpu/os.c
index 36637af6ce4..3e37c930b06 100644
--- a/arch/sandbox/cpu/os.c
+++ b/arch/sandbox/cpu/os.c
@@ -44,6 +44,14 @@ ssize_t os_read(int fd, void *buf, size_t count)
 	return read(fd, buf, count);
 }
 
+ssize_t os_read_no_block(int fd, void *buf, size_t count)
+{
+	const int flags = fcntl(fd, F_GETFL, 0);
+
+	fcntl(fd, F_SETFL, flags | O_NONBLOCK);
+	return os_read(fd, buf, count);
+}
+
 ssize_t os_write(int fd, const void *buf, size_t count)
 {
 	return write(fd, buf, count);