Negotiate individual buffer size dynamically

If slave support VIRTIO_RPMSG_F_BUFSZ(0x04) feature, master
determine the buffer size from config space(first 8 bytes),
otherwise the default size(512 bytes) will be used.

Signed-off-by: Chao An <anchao@pinecone.net>

lib/include/openamp/remoteproc.h

@@ -303,6 +303,23 @@ struct fw_rsc_vdev {
 	struct fw_rsc_vdev_vring vring[0];
 } METAL_PACKED_END;
 
+/**
+ * struct fw_rsc_config - configuration space declaration
+ * @txbuf_size: the tx buffer size
+ * @rxbuf_size: the rx buffer size
+ * @reserved: reserved (must be zero)
+ *
+ * This structure immediately follow fw_rsc_vdev to provide the config info.
+ */
+METAL_PACKED_BEGIN
+struct fw_rsc_config {
+	/* The tx/rx individual buffer size(if VIRTIO_RPMSG_F_BUFSZ) */
+	uint32_t txbuf_size;
+	uint32_t rxbuf_size;
+	uint32_t reserved[14]; /* Reserve for the future use */
+	/* Put the customize config here */
+} METAL_PACKED_END;
+
 /**
  * struct fw_rsc_vendor - remote processor vendor specific resource
  * @len: length of the resource

lib/include/openamp/rpmsg_virtio.h

@@ -16,6 +16,7 @@
 #include <metal/mutex.h>
 #include <openamp/rpmsg.h>
 #include <openamp/virtio.h>
+#include <openamp/remoteproc.h>
 
 #if defined __cplusplus
 extern "C" {
@@ -28,6 +29,7 @@ extern "C" {
 
 /* The feature bitmap for virtio rpmsg */
 #define VIRTIO_RPMSG_F_NS	0 /* RP supports name service notifications */
+#define VIRTIO_RPMSG_F_BUFSZ	2 /* RP supports buffer size negotiation */
 
 /**
  * struct rpmsg_virtio_shm_pool - shared memory pool used for rpmsg buffers
@@ -44,6 +46,7 @@ struct rpmsg_virtio_shm_pool {
 /**
  * struct rpmsg_virtio_device - representation of a rpmsg device based on virtio
  * @rdev: rpmsg device, first property in the struct
+ * @config: rpmsg config information
  * @vdev: pointer to the virtio device
  * @rvq: pointer to receive virtqueue
  * @svq: pointer to send virtqueue
@@ -52,6 +55,7 @@ struct rpmsg_virtio_shm_pool {
  */
 struct rpmsg_virtio_device {
 	struct rpmsg_device rdev;
+	struct fw_rsc_config config;
 	struct virtio_device *vdev;
 	struct virtqueue *rvq;
 	struct virtqueue *svq;

lib/rpmsg/rpmsg_virtio.c

@@ -145,8 +145,8 @@ static void *rpmsg_virtio_get_tx_buffer(struct rpmsg_virtio_device *rvdev,
 		data = virtqueue_get_buffer(rvdev->svq, len, idx);
 		if (!data) {
 			data = rpmsg_virtio_shm_pool_get_buffer(rvdev->shpool,
-							RPMSG_BUFFER_SIZE);
-			*len = RPMSG_BUFFER_SIZE;
+						    rvdev->config.rxbuf_size);
+			*len = rvdev->config.rxbuf_size;
 		}
 	}
 #endif /*!VIRTIO_SLAVE_ONLY*/
@@ -238,7 +238,7 @@ static int _rpmsg_virtio_get_buffer_size(struct rpmsg_virtio_device *rvdev)
 		 * If device role is Master then buffers are provided by us,
 		 * so just provide the macro.
 		 */
-		length = RPMSG_BUFFER_SIZE - sizeof(struct rpmsg_hdr);
+		length = rvdev->config.rxbuf_size - sizeof(struct rpmsg_hdr);
 	}
 #endif /*!VIRTIO_SLAVE_ONLY*/
 
@@ -529,7 +529,10 @@ int rpmsg_init_vdev(struct rpmsg_virtio_device *rvdev,
 	rvdev->vdev = vdev;
 	rdev->ns_bind_cb = ns_bind_cb;
 	vdev->priv = rvdev;
+	rvdev->config.txbuf_size = RPMSG_BUFFER_SIZE;
+	rvdev->config.rxbuf_size = RPMSG_BUFFER_SIZE;
 	rdev->ops.send_offchannel_raw = rpmsg_virtio_send_offchannel_raw;
+
 	role = rpmsg_virtio_get_role(rvdev);
 
 #ifndef VIRTIO_MASTER_ONLY
@@ -541,6 +544,13 @@ int rpmsg_init_vdev(struct rpmsg_virtio_device *rvdev,
 	vdev->features = rpmsg_virtio_get_features(rvdev);
 	rdev->support_ns = !!(vdev->features & (1 << VIRTIO_RPMSG_F_NS));
 
+	if (vdev->features & (1 << VIRTIO_RPMSG_F_BUFSZ)) {
+		rpmsg_virtio_read_config(rvdev,
+			0,
+			&rvdev->config,
+			sizeof(rvdev->config));
+	}
+
 #ifndef VIRTIO_SLAVE_ONLY
 	if (role == RPMSG_MASTER) {
 		/*
@@ -601,11 +611,11 @@ int rpmsg_init_vdev(struct rpmsg_virtio_device *rvdev,
 		unsigned int idx;
 		void *buffer;
 
-		vqbuf.len = RPMSG_BUFFER_SIZE;
+		vqbuf.len = rvdev->config.txbuf_size;
 		for (idx = 0; idx < rvdev->rvq->vq_nentries; idx++) {
 			/* Initialize TX virtqueue buffers for remote device */
 			buffer = rpmsg_virtio_shm_pool_get_buffer(shpool,
-							RPMSG_BUFFER_SIZE);
+						rvdev->config.txbuf_size);
 
 			if (!buffer) {
 				return RPMSG_ERR_NO_BUFF;
@@ -616,7 +626,7 @@ int rpmsg_init_vdev(struct rpmsg_virtio_device *rvdev,
 			metal_io_block_set(shm_io,
 					   metal_io_virt_to_offset(shm_io,
 								   buffer),
-					   0x00, RPMSG_BUFFER_SIZE);
+					   0x00, rvdev->config.txbuf_size);
 			status =
 				virtqueue_add_buffer(rvdev->rvq, &vqbuf, 0, 1,
 						     buffer);