[PATCH 4/4] serial: embed the rx buffer in struct serial_dev_priv

[Rasmus Villemoes <ravi@prevas.dk>]

The initialization of upriv->buf doesn't check for a NULL return. But
there's actually no point in doing a separate, unconditional malloc()
in post_probe; we can just make serial_dev_priv contain the rx buffer
itself, and let the (larger) allocation be handled by the driver core
when it allocates the ->per_device_auto. The total run-time memory
used is mostly the same, we reduce the code size a little, and as a
bonus, struct serial_dev_priv does not contain the unused members when
!SERIAL_RX_BUFFER.

Signed-off-by: Rasmus Villemoes <ravi@prevas.dk>
---
 drivers/serial/serial-uclass.c | 5 -----
 include/serial.h               | 4 +++-
 2 files changed, 3 insertions(+), 6 deletions(-)

diff --git a/drivers/serial/serial-uclass.c b/drivers/serial/serial-uclass.c
index 484f0f7d3e8..d737e25223d 100644
--- a/drivers/serial/serial-uclass.c
+++ b/drivers/serial/serial-uclass.c
@@ -588,11 +588,6 @@ static int serial_post_probe(struct udevice *dev)
 	sdev.getc = serial_stub_getc;
 	sdev.tstc = serial_stub_tstc;
 
-#if CONFIG_IS_ENABLED(SERIAL_RX_BUFFER)
-	/* Allocate the RX buffer */
-	upriv->buf = malloc(CONFIG_SERIAL_RX_BUFFER_SIZE);
-#endif
-
 	stdio_register_dev(&sdev, &upriv->sdev);
 #endif
 	return 0;
diff --git a/include/serial.h b/include/serial.h
index 14563239b7d..eabc49f820f 100644
--- a/include/serial.h
+++ b/include/serial.h
@@ -298,9 +298,11 @@ struct dm_serial_ops {
 struct serial_dev_priv {
 	struct stdio_dev *sdev;
 
-	char *buf;
+#if CONFIG_IS_ENABLED(SERIAL_RX_BUFFER)
+	char buf[CONFIG_SERIAL_RX_BUFFER_SIZE];
 	uint rd_ptr;
 	uint wr_ptr;
+#endif
 };
 
 /* Access the serial operations for a device */
-- 
2.46.2