rpmsg_virtio: add new virtio feature bit

Introduce new feature bit that allows rpmsg buffer size via virtio
device config space. If the feature is available then, driver will set
single rpmsg buffer size from virtio device config space in the resource
table.

Signed-off-by: Tanmay Shah <tanmay.shah@amd.com>

Author: tnmysh

lib/include/openamp/rpmsg_virtio.h

@@ -15,6 +15,7 @@
 #include <metal/io.h>
 #include <metal/mutex.h>
 #include <metal/cache.h>
+#include <metal/compiler.h>
 #include <openamp/rpmsg.h>
 #include <openamp/virtio.h>
 
@@ -29,6 +30,7 @@ extern "C" {
 
 /* The feature bitmap for virtio rpmsg */
 #define VIRTIO_RPMSG_F_NS	0 /* RP supports name service notifications */
+#define VIRTIO_RPMSG_F_BUFSZ    1 /* fw provides tx and rx single buf size */
 
 #if defined(VIRTIO_USE_DCACHE)
 #define BUFFER_FLUSH(x, s)		metal_cache_flush(x, s)
@@ -59,7 +61,11 @@ struct rpmsg_virtio_shm_pool {
  * This structure is used by the RPMsg virtio host to configure the virtiio
  * layer.
  */
+METAL_PACKED_BEGIN
 struct rpmsg_virtio_config {
+	/** version of this struct */
+	uint16_t version;
+
 	/** The size of the buffer used to send data from host to remote */
 	uint32_t h2r_buf_size;
 
@@ -68,7 +74,7 @@ struct rpmsg_virtio_config {
 
 	/** The flag for splitting shared memory pool to TX and RX */
 	bool split_shpool;
-};
+} METAL_PACKED_END;
 
 /** @brief Representation of a RPMsg device based on virtio */
 struct rpmsg_virtio_device {

lib/rpmsg/rpmsg_virtio.c

@@ -62,6 +62,7 @@ struct vbuff_reclaimer_t {
 #if VIRTIO_ENABLED(VIRTIO_DRIVER_SUPPORT)
 #define RPMSG_VIRTIO_DEFAULT_CONFIG                \
 	(&(const struct rpmsg_virtio_config) {     \
+		.version = 1,			   \
 		.h2r_buf_size = RPMSG_BUFFER_SIZE, \
 		.r2h_buf_size = RPMSG_BUFFER_SIZE, \
 		.split_shpool = false,             \