512 bytes isn't always suitable for all case, let firmware
maker decide the best value from resource table.
enable by VIRTIO_RPMSG_F_BUFSZ feature bit.

Signed-off-by: Tanmay Shah <[email protected]>
---

Test done:
  - Verify this patch works with the existing firmware
  - Verify this patch works with the firmware that configures
    differt tx & rx buf size

Changes in v2:
  - %s/sbuf_size/tx_buf_size/
  - %s/rbuf_size/rx_buf_size/
  - fix typo
  - do not use ALIGN on buf size, rely on allocator
  - make err msg more explicit, %s/vdev config:/bad vdev config/
  - fix license and add AMD copyrights in the header virtio_rpmsg.h
  - Assign bit 1 to VIRTIO_RPMSG_F_BUFSZ feature
  - use __virtio32 over __u32
  - add version field to virtio rpmsg config structure
  - move linux/virtio_rpmsg.h to linux/rpmsg/virtio_rpmsg.h

 drivers/rpmsg/virtio_rpmsg_bus.c   | 70 ++++++++++++++++++++++--------
 include/linux/rpmsg/virtio_rpmsg.h | 27 ++++++++++++
 2 files changed, 79 insertions(+), 18 deletions(-)
 create mode 100644 include/linux/rpmsg/virtio_rpmsg.h

diff --git a/drivers/rpmsg/virtio_rpmsg_bus.c b/drivers/rpmsg/virtio_rpmsg_bus.c
index e59d8cf9b975..8116d94413cc 100644
--- a/drivers/rpmsg/virtio_rpmsg_bus.c
+++ b/drivers/rpmsg/virtio_rpmsg_bus.c
@@ -20,6 +20,7 @@
 #include <linux/rpmsg.h>
 #include <linux/rpmsg/byteorder.h>
 #include <linux/rpmsg/ns.h>
+#include <linux/rpmsg/virtio_rpmsg.h>
 #include <linux/scatterlist.h>
 #include <linux/slab.h>
 #include <linux/sched.h>
@@ -39,7 +40,8 @@
  * @tx_bufs:   kernel address of tx buffers
  * @num_rx_buf:        total number of buffers for rx
  * @num_tx_buf:        total number of buffers for tx
- * @buf_size:  size of one rx or tx buffer
+ * @rx_buf_size: size of one rx buffer
+ * @tx_buf_size: size of one tx buffer
  * @last_sbuf: index of last tx buffer used
  * @bufs_dma:  dma base addr of the buffers
  * @tx_lock:   protects svq and tx_bufs, to allow concurrent senders.
@@ -59,7 +61,8 @@ struct virtproc_info {
        void *rx_bufs, *tx_bufs;
        unsigned int num_rx_buf;
        unsigned int num_tx_buf;
-       unsigned int buf_size;
+       unsigned int rx_buf_size;
+       unsigned int tx_buf_size;
        int last_sbuf;
        dma_addr_t bufs_dma;
        struct mutex tx_lock;
@@ -68,9 +71,6 @@ struct virtproc_info {
        wait_queue_head_t sendq;
 };
 
-/* The feature bitmap for virtio rpmsg */
-#define VIRTIO_RPMSG_F_NS      0 /* RP supports name service notifications */
-
 /**
  * struct rpmsg_hdr - common header for all rpmsg messages
  * @src: source address
@@ -128,7 +128,7 @@ struct virtio_rpmsg_channel {
  * processor.
  */
 #define MAX_RPMSG_NUM_BUFS     (256)
-#define MAX_RPMSG_BUF_SIZE     (512)
+#define DEFAULT_RPMSG_BUF_SIZE (512)
 
 /*
  * Local addresses are dynamically allocated on-demand.
@@ -444,7 +444,7 @@ static void *get_a_tx_buf(struct virtproc_info *vrp)
 
        /* either pick the next unused tx buffer */
        if (vrp->last_sbuf < vrp->num_tx_buf)
-               ret = vrp->tx_bufs + vrp->buf_size * vrp->last_sbuf++;
+               ret = vrp->tx_bufs + vrp->tx_buf_size * vrp->last_sbuf++;
        /* or recycle a used one */
        else
                ret = virtqueue_get_buf(vrp->svq, &len);
@@ -514,7 +514,7 @@ static int rpmsg_send_offchannel_raw(struct rpmsg_device 
*rpdev,
         * messaging), or to improve the buffer allocator, to support
         * variable-length buffer sizes.
         */
-       if (len > vrp->buf_size - sizeof(struct rpmsg_hdr)) {
+       if (len > vrp->tx_buf_size - sizeof(struct rpmsg_hdr)) {
                dev_err(dev, "message is too big (%d)\n", len);
                return -EMSGSIZE;
        }
@@ -647,7 +647,7 @@ static ssize_t virtio_rpmsg_get_mtu(struct rpmsg_endpoint 
*ept)
        struct rpmsg_device *rpdev = ept->rpdev;
        struct virtio_rpmsg_channel *vch = to_virtio_rpmsg_channel(rpdev);
 
-       return vch->vrp->buf_size - sizeof(struct rpmsg_hdr);
+       return vch->vrp->tx_buf_size - sizeof(struct rpmsg_hdr);
 }
 
 static int rpmsg_recv_single(struct virtproc_info *vrp, struct device *dev,
@@ -673,7 +673,7 @@ static int rpmsg_recv_single(struct virtproc_info *vrp, 
struct device *dev,
         * We currently use fixed-sized buffers, so trivially sanitize
         * the reported payload length.
         */
-       if (len > vrp->buf_size ||
+       if (len > vrp->rx_buf_size ||
            msg_len > (len - sizeof(struct rpmsg_hdr))) {
                dev_warn(dev, "inbound msg too big: (%d, %d)\n", len, msg_len);
                return -EINVAL;
@@ -706,7 +706,7 @@ static int rpmsg_recv_single(struct virtproc_info *vrp, 
struct device *dev,
                dev_warn_ratelimited(dev, "msg received with no recipient\n");
 
        /* publish the real size of the buffer */
-       rpmsg_sg_init(&sg, msg, vrp->buf_size);
+       rpmsg_sg_init(&sg, msg, vrp->rx_buf_size);
 
        /* add the buffer back to the remote processor's virtqueue */
        err = virtqueue_add_inbuf(vrp->rvq, &sg, 1, msg, GFP_KERNEL);
@@ -824,6 +824,7 @@ static int rpmsg_probe(struct virtio_device *vdev)
        int err = 0, i;
        size_t total_buf_space;
        bool notify;
+       u16 version;
 
        vrp = kzalloc_obj(*vrp);
        if (!vrp)
@@ -855,9 +856,41 @@ static int rpmsg_probe(struct virtio_device *vdev)
        else
                vrp->num_tx_buf = MAX_RPMSG_NUM_BUFS;
 
-       vrp->buf_size = MAX_RPMSG_BUF_SIZE;
+       /*
+        * If VIRTIO_RPMSG_F_BUFSZ feature is supported, then configure buf
+        * size from virtio device config space from the resource table.
+        * If the feature is not supported, then assign default buf size.
+        */
+       if (virtio_has_feature(vdev, VIRTIO_RPMSG_F_BUFSZ)) {
+               /* note: virtio_rpmsg_config is defined from remote view */
+               version = 0;
+               virtio_cread(vdev, struct virtio_rpmsg_config,
+                            version, &version);
+               virtio_cread(vdev, struct virtio_rpmsg_config,
+                            txbuf_size, &vrp->rx_buf_size);
+               virtio_cread(vdev, struct virtio_rpmsg_config,
+                            rxbuf_size, &vrp->tx_buf_size);
+
+               /* The buffers must hold at least the rpmsg header */
+               if (vrp->rx_buf_size < sizeof(struct rpmsg_hdr) ||
+                   vrp->tx_buf_size < sizeof(struct rpmsg_hdr)) {
+                       dev_err(&vdev->dev,
+                               "bad vdev config: rx buf sz = %d, tx buf sz = 
%d\n",
+                               vrp->rx_buf_size, vrp->tx_buf_size);
+                       err = -EINVAL;
+                       goto vqs_del;
+               }
+
+               dev_dbg(&vdev->dev,
+                       "vdev config: version=%d, rx buf sz = 0x%x, tx buf sz = 
0x%x\n",
+                       version, vrp->rx_buf_size, vrp->tx_buf_size);
+       } else {
+               vrp->rx_buf_size = DEFAULT_RPMSG_BUF_SIZE;
+               vrp->tx_buf_size = DEFAULT_RPMSG_BUF_SIZE;
+       }
 
-       total_buf_space = (vrp->num_rx_buf + vrp->num_tx_buf) * vrp->buf_size;
+       total_buf_space = (vrp->num_rx_buf * vrp->rx_buf_size) +
+                         (vrp->num_tx_buf * vrp->tx_buf_size);
 
        /* allocate coherent memory for the buffers */
        bufs_va = dma_alloc_coherent(vdev->dev.parent,
@@ -875,14 +908,14 @@ static int rpmsg_probe(struct virtio_device *vdev)
        vrp->rx_bufs = bufs_va;
 
        /* and second part is dedicated for TX */
-       vrp->tx_bufs = bufs_va + vrp->num_rx_buf * vrp->buf_size;
+       vrp->tx_bufs = bufs_va + (vrp->num_rx_buf * vrp->rx_buf_size);
 
        /* set up the receive buffers */
        for (i = 0; i < vrp->num_rx_buf; i++) {
                struct scatterlist sg;
-               void *cpu_addr = vrp->rx_bufs + i * vrp->buf_size;
+               void *cpu_addr = vrp->rx_bufs + i * vrp->rx_buf_size;
 
-               rpmsg_sg_init(&sg, cpu_addr, vrp->buf_size);
+               rpmsg_sg_init(&sg, cpu_addr, vrp->rx_buf_size);
 
                err = virtqueue_add_inbuf(vrp->rvq, &sg, 1, cpu_addr,
                                          GFP_KERNEL);
@@ -965,8 +998,8 @@ static int rpmsg_remove_device(struct device *dev, void 
*data)
 static void rpmsg_remove(struct virtio_device *vdev)
 {
        struct virtproc_info *vrp = vdev->priv;
-       unsigned int num_bufs = vrp->num_rx_buf + vrp->num_tx_buf;
-       size_t total_buf_space = num_bufs * vrp->buf_size;
+       size_t total_buf_space = (vrp->num_rx_buf * vrp->rx_buf_size) +
+                                (vrp->num_tx_buf * vrp->tx_buf_size);
        int ret;
 
        virtio_reset_device(vdev);
@@ -992,6 +1025,7 @@ static struct virtio_device_id id_table[] = {
 
 static unsigned int features[] = {
        VIRTIO_RPMSG_F_NS,
+       VIRTIO_RPMSG_F_BUFSZ,
 };
 
 static struct virtio_driver virtio_ipc_driver = {
diff --git a/include/linux/rpmsg/virtio_rpmsg.h 
b/include/linux/rpmsg/virtio_rpmsg.h
new file mode 100644
index 000000000000..285918be68b9
--- /dev/null
+++ b/include/linux/rpmsg/virtio_rpmsg.h
@@ -0,0 +1,27 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Copyright (C) Pinecone Inc. 2019
+ * Copyright (C) Xiang Xiao <[email protected]>
+ * Copyright (C) Advanced Micro Devices, Inc.
+ */
+
+#ifndef _LINUX_VIRTIO_RPMSG_H
+#define _LINUX_VIRTIO_RPMSG_H
+
+#include <linux/types.h>
+#include <linux/virtio_types.h>
+
+/* The feature bitmap for virtio rpmsg */
+#define VIRTIO_RPMSG_F_NS      0 /* RP supports name service notifications */
+#define VIRTIO_RPMSG_F_BUFSZ   1 /* RP get buffer size from config space */
+
+struct virtio_rpmsg_config {
+       __virtio16 version;
+       /* The tx/rx individual buffer size(if VIRTIO_RPMSG_F_BUFSZ) */
+       __virtio32 txbuf_size;
+       __virtio32 rxbuf_size;
+       __virtio32 reserved[14]; /* Reserve for the future use */
+       /* Put the customize config here */
+} __packed;
+
+#endif /* _LINUX_VIRTIO_RPMSG_H */
-- 
2.34.1


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