[PATCH v4 11/11] net: qrtr: mhi: Report endpoint id in sysfs

[Mihai Moldovan <ionic@ionic.de>]

From: Denis Kenzior <denkenz@gmail.com>

Add a read-only 'endpoint' sysfs entry that contains the qrtr endpoint
identifier assigned to this mhi device.  Can be used to direct / receive
qrtr traffic only from a particular MHI device.

Signed-off-by: Denis Kenzior <denkenz@gmail.com>
Reviewed-by: Marcel Holtmann <marcel@holtmann.org>
Reviewed-by: Andy Gross <agross@kernel.org>
Signed-off-by: Mihai Moldovan <ionic@ionic.de>

---

v4:
  - no changes
  - Link to v3: https://msgid.link/e1f5b82cd25b2ac433b1bd7e83e22604e6b24f03.1753313000.git.ionic@ionic.de

v3:
  - rebase against current master
  - Link to v2: https://msgid.link/1a49dec96d5c2c5258c9df935d8c9381793d4ddd.1752947108.git.ionic@ionic.de

v2:
  - rebase against current master
  - use %u formatter instead of %d when printing endpoint id (u32) as
    per review comment
  - Link to v1: https://msgid.link/20241018181842.1368394-11-denkenz@gmail.com
---
 net/qrtr/mhi.c | 14 ++++++++++++++
 1 file changed, 14 insertions(+)

diff --git a/net/qrtr/mhi.c b/net/qrtr/mhi.c
index 69f53625a049..9a23c888e234 100644
--- a/net/qrtr/mhi.c
+++ b/net/qrtr/mhi.c
@@ -72,6 +72,16 @@ static int qcom_mhi_qrtr_send(struct qrtr_endpoint *ep, struct sk_buff *skb)
 	return rc;
 }
 
+static ssize_t endpoint_show(struct device *dev,
+			     struct device_attribute *attr, char *buf)
+{
+	struct qrtr_mhi_dev *qdev = dev_get_drvdata(dev);
+
+	return sprintf(buf, "%u\n", qdev->ep.id);
+}
+
+static DEVICE_ATTR_RO(endpoint);
+
 static int qcom_mhi_qrtr_probe(struct mhi_device *mhi_dev,
 			       const struct mhi_device_id *id)
 {
@@ -91,6 +101,9 @@ static int qcom_mhi_qrtr_probe(struct mhi_device *mhi_dev,
 	if (rc)
 		return rc;
 
+	if (device_create_file(&mhi_dev->dev, &dev_attr_endpoint) < 0)
+		dev_err(qdev->dev, "Failed to create endpoint attribute\n");
+
 	/* start channels */
 	rc = mhi_prepare_for_transfer_autoqueue(mhi_dev);
 	if (rc) {
@@ -107,6 +120,7 @@ static void qcom_mhi_qrtr_remove(struct mhi_device *mhi_dev)
 {
 	struct qrtr_mhi_dev *qdev = dev_get_drvdata(&mhi_dev->dev);
 
+	device_remove_file(&mhi_dev->dev, &dev_attr_endpoint);
 	qrtr_endpoint_unregister(&qdev->ep);
 	mhi_unprepare_from_transfer(mhi_dev);
 	dev_set_drvdata(&mhi_dev->dev, NULL);
-- 
2.50.0