linux-kernel - [PATCH V2 3/3] rpmsg: char: Add TIOCMGET/TIOCMSET ioctl support

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Date:   Wed, 19 Jan 2022 01:13:13 +0530
From:   Deepak Kumar Singh <quic_deesin@...cinc.com>
To:     <bjorn.andersson@...aro.org>, <swboyd@...omium.org>,
        <quic_clew@...cinc.com>, <mathieu.poirier@...aro.org>
CC:     <linux-kernel@...r.kernel.org>, <linux-arm-msm@...r.kernel.org>,
        <linux-remoteproc@...r.kernel.org>,
        Deepak Kumar Singh <quic_deesin@...cinc.com>,
        Ohad Ben-Cohen <ohad@...ery.com>
Subject: [PATCH V2 3/3] rpmsg: char: Add TIOCMGET/TIOCMSET ioctl support

Add TICOMGET and TIOCMSET ioctl support for rpmsg char device nodes
to get/set the low level transport signals.

Signed-off-by: Chris Lew <quic_clew@...cinc.com>
Signed-off-by: Deepak Kumar Singh <quic_deesin@...cinc.com>
---
 drivers/rpmsg/rpmsg_char.c | 47 ++++++++++++++++++++++++++++++++++++++++++----
 1 file changed, 43 insertions(+), 4 deletions(-)

diff --git a/drivers/rpmsg/rpmsg_char.c b/drivers/rpmsg/rpmsg_char.c
index b5907b8..c03a118 100644
--- a/drivers/rpmsg/rpmsg_char.c
+++ b/drivers/rpmsg/rpmsg_char.c
@@ -19,6 +19,7 @@
 #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>
 
@@ -74,6 +75,9 @@ struct rpmsg_eptdev {
 	spinlock_t queue_lock;
 	struct sk_buff_head queue;
 	wait_queue_head_t readq;
+
+	u32 rsigs;
+	bool sig_pending;
 };
 
 static int rpmsg_eptdev_destroy(struct device *dev, void *data)
@@ -112,7 +116,18 @@ 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_sigs_cb(struct rpmsg_device *rpdev, void *priv, u32 sigs)
+{
+	struct rpmsg_eptdev *eptdev = priv;
+
+	eptdev->rsigs = sigs;
+	eptdev->sig_pending = true;
+
 	wake_up_interruptible(&eptdev->readq);
 
 	return 0;
@@ -137,6 +152,7 @@ static int rpmsg_eptdev_open(struct inode *inode, struct file *filp)
 		return -EINVAL;
 	}
 
+	ept->sig_cb = rpmsg_sigs_cb;
 	eptdev->ept = ept;
 	filp->private_data = eptdev;
 
@@ -155,6 +171,7 @@ static int rpmsg_eptdev_release(struct inode *inode, struct file *filp)
 		eptdev->ept = NULL;
 	}
 	mutex_unlock(&eptdev->ept_lock);
+	eptdev->sig_pending = false;
 
 	/* Discard all SKBs */
 	skb_queue_purge(&eptdev->queue);
@@ -265,6 +282,9 @@ static __poll_t rpmsg_eptdev_poll(struct file *filp, poll_table *wait)
 	if (!skb_queue_empty(&eptdev->queue))
 		mask |= EPOLLIN | EPOLLRDNORM;
 
+	if (eptdev->sig_pending)
+		mask |= EPOLLPRI;
+
 	mask |= rpmsg_poll(eptdev->ept, filp, wait);
 
 	return mask;
@@ -274,11 +294,30 @@ static long rpmsg_eptdev_ioctl(struct file *fp, unsigned int cmd,
 			       unsigned long arg)
 {
 	struct rpmsg_eptdev *eptdev = fp->private_data;
+	bool set;
+	u32 val;
+	int ret;
 
-	if (cmd != RPMSG_DESTROY_EPT_IOCTL)
-		return -EINVAL;
+	switch (cmd) {
+	case TIOCMGET:
+		eptdev->sig_pending = false;
+		ret = put_user(eptdev->rsigs, (int __user *)arg);
+		break;
+	case TIOCMSET:
+		ret = get_user(val, (int __user *)arg);
+		if (ret)
+			break;
+		set = (val & TIOCM_DTR) ? true : false;
+		ret = rpmsg_set_flow_control(eptdev->ept, set);
+		break;
+	case RPMSG_DESTROY_EPT_IOCTL:
+		ret = rpmsg_eptdev_destroy(&eptdev->dev, NULL);
+		break;
+	default:
+		ret = -EINVAL;
+	}
 
-	return rpmsg_eptdev_destroy(&eptdev->dev, NULL);
+	return ret;
 }
 
 static const struct file_operations rpmsg_eptdev_fops = {
-- 
2.7.4