[PATCH V7 3/3] rpmsg: char: Add RPMSG GET/SET FLOWCONTROL IOCTL support

From: Sarannya S
Date: Sat Apr 22 2023 - 06:43:23 EST


From: Chris Lew <quic_clew@xxxxxxxxxxx>

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@xxxxxxxxxxx>
Signed-off-by: Deepak Kumar Singh <quic_deesin@xxxxxxxxxxx>
Signed-off-by: Sarannya S <quic_sarannya@xxxxxxxxxxx>
---
drivers/rpmsg/rpmsg_char.c | 49 ++++++++++++++++++++++++++++++++++++++++------
include/uapi/linux/rpmsg.h | 11 ++++++++++-
2 files changed, 53 insertions(+), 7 deletions(-)

diff --git a/drivers/rpmsg/rpmsg_char.c b/drivers/rpmsg/rpmsg_char.c
index a271fce..d50908f 100644
--- a/drivers/rpmsg/rpmsg_char.c
+++ b/drivers/rpmsg/rpmsg_char.c
@@ -23,6 +23,7 @@
#include <linux/rpmsg.h>
#include <linux/skbuff.h>
#include <linux/slab.h>
+#include <linux/termios.h>
#include <linux/uaccess.h>
#include <uapi/linux/rpmsg.h>

@@ -68,6 +69,8 @@ struct rpmsg_eptdev {
struct sk_buff_head queue;
wait_queue_head_t readq;

+ bool remote_flow;
+ bool remote_flow_updated;
};

int rpmsg_chrdev_eptdev_destroy(struct device *dev, void *data)
@@ -116,6 +119,18 @@ 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 = 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 +167,7 @@ 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 +188,7 @@ 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 +302,9 @@ 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 +317,31 @@ 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, (int __user *)arg);
+ break;
+ case RPMSG_SET_INCOMING_FLOWCONTROL:
+ 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 1637e68..c955e27 100644
--- a/include/uapi/linux/rpmsg.h
+++ b/include/uapi/linux/rpmsg.h
@@ -10,7 +10,6 @@
#include <linux/types.h>

#define RPMSG_ADDR_ANY 0xFFFFFFFF
-
/**
* struct rpmsg_endpoint_info - endpoint info representation
* @name: name of service
@@ -43,4 +42,14 @@ struct rpmsg_endpoint_info {
*/
#define RPMSG_RELEASE_DEV_IOCTL _IOW(0xb5, 0x4, struct rpmsg_endpoint_info)

+/**
+ * Set the flow control for the remote rpmsg char device.
+ */
+#define RPMSG_GET_OUTGOING_FLOWCONTROL _IOW(0xb5, 0x5, struct rpmsg_endpoint_info)
+
+/**
+ * Set the flow control for the local rpmsg char device.
+ */
+#define RPMSG_SET_INCOMING_FLOWCONTROL _IOW(0xb5, 0x6, struct rpmsg_endpoint_info)
+
#endif
--
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