[PATCH V5 3/3] rpmsg: char: Add RPMSG GET/SET SIGNAL IOCTL support

From: Sarannya S
Date: Tue Feb 21 2023 - 11:04:59 EST


Add RPMSG_GET_SIGNAL_IOCTL and RPMSG_SET_SIGNAL_IOCTL 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 | 58 ++++++++++++++++++++++++++++++++++++++++------
include/uapi/linux/rpmsg.h | 12 +++++++++-
2 files changed, 62 insertions(+), 8 deletions(-)

diff --git a/drivers/rpmsg/rpmsg_char.c b/drivers/rpmsg/rpmsg_char.c
index 3e0b8f3..45a22e8 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;

+ u32 remote_signals;
+ bool flow_control;
};

int rpmsg_chrdev_eptdev_destroy(struct device *dev, void *data)
@@ -109,7 +112,22 @@ static int rpmsg_ept_cb(struct rpmsg_device *rpdev, void *buf, int len,
skb_queue_tail(&eptdev->queue, skb);
spin_unlock(&eptdev->queue_lock);

- /* wake up any blocking processes, waiting for new data */
+ wake_up_interruptible(&eptdev->readq);
+
+ return 0;
+}
+
+static int rpmsg_ept_flow_cb(struct rpmsg_device *rpdev, void *priv, bool enable)
+{
+ struct rpmsg_eptdev *eptdev = priv;
+
+ if (enable)
+ eptdev->remote_signals = RPMSG_FLOW_CONTROL_ON;
+ else
+ eptdev->remote_signals = 0;
+
+ eptdev->flow_control = true;
+
wake_up_interruptible(&eptdev->readq);

return 0;
@@ -146,6 +164,7 @@ 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);
@@ -166,6 +185,7 @@ static int rpmsg_eptdev_release(struct inode *inode, struct file *filp)
eptdev->ept = NULL;
}
mutex_unlock(&eptdev->ept_lock);
+ eptdev->flow_control = false;

/* Discard all SKBs */
skb_queue_purge(&eptdev->queue);
@@ -279,6 +299,9 @@ static __poll_t rpmsg_eptdev_poll(struct file *filp, poll_table *wait)
if (!skb_queue_empty(&eptdev->queue))
mask |= EPOLLIN | EPOLLRDNORM;

+ if (eptdev->flow_control)
+ mask |= EPOLLPRI;
+
mask |= rpmsg_poll(eptdev->ept, filp, wait);

return mask;
@@ -289,14 +312,35 @@ 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;
+ u32 val;
+ int ret;

- /* Don't allow to destroy a default endpoint. */
- if (eptdev->default_ept)
- return -EINVAL;
+ switch (cmd) {
+ case RPMSG_GET_SIGNAL_IOCTL:
+ eptdev->flow_control = false;
+ ret = put_user(eptdev->remote_signals, (int __user *)arg);
+ break;
+ case RPMSG_SET_SIGNAL_IOCTL:
+ ret = get_user(val, (int __user *)arg);
+ if (ret)
+ break;
+ set = (val & RPMSG_FLOW_CONTROL_ON) ? true : false;
+ ret = rpmsg_set_flow_control(eptdev->ept, set);
+ 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..c549649 100644
--- a/include/uapi/linux/rpmsg.h
+++ b/include/uapi/linux/rpmsg.h
@@ -10,7 +10,7 @@
#include <linux/types.h>

#define RPMSG_ADDR_ANY 0xFFFFFFFF
-
+#define RPMSG_FLOW_CONTROL_ON 0x001
/**
* struct rpmsg_endpoint_info - endpoint info representation
* @name: name of service
@@ -43,4 +43,14 @@ struct rpmsg_endpoint_info {
*/
#define RPMSG_RELEASE_DEV_IOCTL _IOW(0xb5, 0x4, struct rpmsg_endpoint_info)

+/**
+ * Get the remote rpmsg char device's flow control signal.
+ */
+#define RPMSG_GET_SIGNAL_IOCTL _IOW(0xb5, 0x5, struct rpmsg_endpoint_info)
+
+/**
+ * Set the flow control for the local rpmsg char device.
+ */
+#define RPMSG_SET_SIGNAL_IOCTL _IOW(0xb5, 0x6, struct rpmsg_endpoint_info)
+
#endif
--
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