rpmsg: char: Add RPMSG GET/SET FLOWCONTROL IOCTL support

Add RPMSG_GET_OUTGOING_FLOWCONTROL and RPMSG_SET_INCOMING_FLOWCONTROL
IOCTL support for rpmsg char device nodes to get/set the low level
transport signals.

Signed-off-by: Chris Lew <quic_clew@quicinc.com>
Signed-off-by: Deepak Kumar Singh <quic_deesin@quicinc.com>
Signed-off-by: Sarannya S <quic_sarannya@quicinc.com>
Acked-by: Arnaud Pouliquen <arnaud.pouliquen@foss.st.com>
Link: https://lore.kernel.org/r/1688679698-31274-4-git-send-email-quic_sarannya@quicinc.com
Signed-off-by: Bjorn Andersson <andersson@kernel.org>

diff --git a/drivers/rpmsg/rpmsg_char.c b/drivers/rpmsg/rpmsg_char.c
index a271fceb16f421ecda950384fc40c67538471192..09833ad05da75cb6ca91f53e4e425cac7fad6fc9 100644 (file)
--- a/drivers/rpmsg/rpmsg_char.c
+++ b/drivers/rpmsg/rpmsg_char.c
@@ -52,6 +52,8 @@ static DEFINE_IDA(rpmsg_minor_ida);
  * @readq:     wait object for incoming queue
  * @default_ept: set to channel default endpoint if the default endpoint should be re-used
  *              on device open to prevent endpoint address update.
+ * remote_flow_restricted: to indicate if the remote has requested for flow to be limited
+ * remote_flow_updated: to indicate if the flow control has been requested
  */
 struct rpmsg_eptdev {
        struct device dev;
@@ -68,6 +70,8 @@ struct rpmsg_eptdev {
        struct sk_buff_head queue;
        wait_queue_head_t readq;
 
+       bool remote_flow_restricted;
+       bool remote_flow_updated;
 };
 
 int rpmsg_chrdev_eptdev_destroy(struct device *dev, void *data)
@@ -116,6 +120,18 @@ static int rpmsg_ept_cb(struct rpmsg_device *rpdev, void *buf, int len,
        return 0;
 }
 
+static int rpmsg_ept_flow_cb(struct rpmsg_device *rpdev, void *priv, bool enable)
+{
+       struct rpmsg_eptdev *eptdev = priv;
+
+       eptdev->remote_flow_restricted = enable;
+       eptdev->remote_flow_updated = true;
+
+       wake_up_interruptible(&eptdev->readq);
+
+       return 0;
+}
+
 static int rpmsg_eptdev_open(struct inode *inode, struct file *filp)
 {
        struct rpmsg_eptdev *eptdev = cdev_to_eptdev(inode->i_cdev);
@@ -152,6 +168,7 @@ static int rpmsg_eptdev_open(struct inode *inode, struct file *filp)
                return -EINVAL;
        }
 
+       ept->flow_cb = rpmsg_ept_flow_cb;
        eptdev->ept = ept;
        filp->private_data = eptdev;
        mutex_unlock(&eptdev->ept_lock);
@@ -172,6 +189,7 @@ static int rpmsg_eptdev_release(struct inode *inode, struct file *filp)
                eptdev->ept = NULL;
        }
        mutex_unlock(&eptdev->ept_lock);
+       eptdev->remote_flow_updated = false;
 
        /* Discard all SKBs */
        skb_queue_purge(&eptdev->queue);
@@ -285,6 +303,9 @@ static __poll_t rpmsg_eptdev_poll(struct file *filp, poll_table *wait)
        if (!skb_queue_empty(&eptdev->queue))
                mask |= EPOLLIN | EPOLLRDNORM;
 
+       if (eptdev->remote_flow_updated)
+               mask |= EPOLLPRI;
+
        mutex_lock(&eptdev->ept_lock);
        mask |= rpmsg_poll(eptdev->ept, filp, wait);
        mutex_unlock(&eptdev->ept_lock);
@@ -297,14 +318,35 @@ static long rpmsg_eptdev_ioctl(struct file *fp, unsigned int cmd,
 {
        struct rpmsg_eptdev *eptdev = fp->private_data;
 
-       if (cmd != RPMSG_DESTROY_EPT_IOCTL)
-               return -EINVAL;
+       bool set;
+       int ret;
 
-       /* Don't allow to destroy a default endpoint. */
-       if (eptdev->default_ept)
-               return -EINVAL;
+       switch (cmd) {
+       case RPMSG_GET_OUTGOING_FLOWCONTROL:
+               eptdev->remote_flow_updated = false;
+               ret = put_user(eptdev->remote_flow_restricted, (int __user *)arg);
+               break;
+       case RPMSG_SET_INCOMING_FLOWCONTROL:
+               if (arg > 1) {
+                       ret = -EINVAL;
+                       break;
+               }
+               set = !!arg;
+               ret = rpmsg_set_flow_control(eptdev->ept, set, eptdev->chinfo.dst);
+               break;
+       case RPMSG_DESTROY_EPT_IOCTL:
+               /* Don't allow to destroy a default endpoint. */
+               if (eptdev->default_ept) {
+                       ret = -EINVAL;
+                       break;
+               }
+               ret = rpmsg_chrdev_eptdev_destroy(&eptdev->dev, NULL);
+               break;
+       default:
+               ret = -EINVAL;
+       }
 
-       return rpmsg_chrdev_eptdev_destroy(&eptdev->dev, NULL);
+       return ret;
 }
 
 static const struct file_operations rpmsg_eptdev_fops = {

diff --git a/include/uapi/linux/rpmsg.h b/include/uapi/linux/rpmsg.h
index 1637e68177d9d9370126f16982449b81186acd7a..f0c8da2b185b43bc58ea4640b66c8fdfa08e970f 100644 (file)
--- a/include/uapi/linux/rpmsg.h
+++ b/include/uapi/linux/rpmsg.h
@@ -43,4 +43,14 @@ struct rpmsg_endpoint_info {
  */
 #define RPMSG_RELEASE_DEV_IOCTL        _IOW(0xb5, 0x4, struct rpmsg_endpoint_info)
 
+/**
+ * Get the flow control state of the remote rpmsg char device.
+ */
+#define RPMSG_GET_OUTGOING_FLOWCONTROL _IOR(0xb5, 0x5, int)
+
+/**
+ * Set the flow control state of the local rpmsg char device.
+ */
+#define RPMSG_SET_INCOMING_FLOWCONTROL _IOR(0xb5, 0x6, int)
+
 #endif