| lists.openwall.net | lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC | |
|
Open Source and information security mailing list archives
| ||
|
Message-Id: <20250923-loopback_mhi-v1-2-8618f31f44aa@oss.qualcomm.com>
Date: Tue, 23 Sep 2025 12:07:42 +0530
From: Sumit Kumar <sumit.kumar@....qualcomm.com>
To: Manivannan Sadhasivam <mani@...nel.org>
Cc: Krishna Chaitanya Chundru <krishna.chundru@....qualcomm.com>,
Akhil Vinod <akhil.vinod@....qualcomm.com>,
Subramanian Ananthanarayanan <subramanian.ananthanarayanan@....qualcomm.com>,
linux-kernel@...r.kernel.org, mhi@...ts.linux.dev,
linux-arm-msm@...r.kernel.org, quic_vpernami@...cinc.com,
Sumit Kumar <sumit.kumar@....qualcomm.com>
Subject: [PATCH 2/2] bus: mhi: ep: Add loopback driver for data path
testing
Add loopback driver for MHI endpoint devices. The driver receives
data on the uplink channel and echoes it back on the downlink
channel using a workqueue for asynchronous processing.
The driver is useful for testing MHI endpoint data path functionality
and debugging communication issues.
Co-developed-by: Krishna Chaitanya Chundru <krishna.chundru@....qualcomm.com>
Signed-off-by: Krishna Chaitanya Chundru <krishna.chundru@....qualcomm.com>
Signed-off-by: Sumit Kumar <sumit.kumar@....qualcomm.com>
---
drivers/bus/mhi/ep/Kconfig | 8 +++
drivers/bus/mhi/ep/Makefile | 1 +
drivers/bus/mhi/ep/mhi_ep_loopback.c | 132 +++++++++++++++++++++++++++++++++++
3 files changed, 141 insertions(+)
diff --git a/drivers/bus/mhi/ep/Kconfig b/drivers/bus/mhi/ep/Kconfig
index 90ab3b040672e0f04181d4802e3062afcc7cf782..ce7b63c2da82a6ca49528517687f4910552c35bb 100644
--- a/drivers/bus/mhi/ep/Kconfig
+++ b/drivers/bus/mhi/ep/Kconfig
@@ -8,3 +8,11 @@ config MHI_BUS_EP
MHI_BUS_EP implements the MHI protocol for the endpoint devices,
such as SDX55 modem connected to the host machine over PCIe.
+
+config MHI_BUS_EP_LOOPBACK
+ tristate "MHI Endpoint loopback driver"
+ depends on MHI_BUS_EP
+ help
+ MHI endpoint loopback driver for data path testing.
+ This driver receives data on the uplink channel and echoes
+ it back on the downlink channel for testing purposes.
diff --git a/drivers/bus/mhi/ep/Makefile b/drivers/bus/mhi/ep/Makefile
index aad85f180b707fb997fcb541837eda9bbbb67437..02e4700e8dc3f860d40290476b0a852286683f8f 100644
--- a/drivers/bus/mhi/ep/Makefile
+++ b/drivers/bus/mhi/ep/Makefile
@@ -1,2 +1,3 @@
obj-$(CONFIG_MHI_BUS_EP) += mhi_ep.o
mhi_ep-y := main.o mmio.o ring.o sm.o
+obj-$(CONFIG_MHI_BUS_EP_LOOPBACK) += mhi_ep_loopback.o
diff --git a/drivers/bus/mhi/ep/mhi_ep_loopback.c b/drivers/bus/mhi/ep/mhi_ep_loopback.c
new file mode 100644
index 0000000000000000000000000000000000000000..89244aca684ffc959a38f8a0c3ad577b2d127c48
--- /dev/null
+++ b/drivers/bus/mhi/ep/mhi_ep_loopback.c
@@ -0,0 +1,132 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (c) Qualcomm Technologies, Inc. and/or its subsidiaries.
+ */
+
+#include <linux/mhi_ep.h>
+#include <linux/mod_devicetable.h>
+#include <linux/module.h>
+#include <linux/skbuff.h>
+
+struct mhi_ep_loopback {
+ struct workqueue_struct *loopback_wq;
+ struct mhi_ep_device *mdev;
+};
+
+struct mhi_ep_loopback_work {
+ struct mhi_ep_device *mdev;
+ struct work_struct work;
+ struct sk_buff *skb;
+};
+
+static void mhi_ep_loopback_work_handler(struct work_struct *work)
+{
+ int ret;
+ struct mhi_ep_loopback_work *mhi_ep_lb_work = container_of(work,
+ struct mhi_ep_loopback_work, work);
+
+ ret = mhi_ep_queue_skb(mhi_ep_lb_work->mdev, mhi_ep_lb_work->skb);
+ if (ret) {
+ dev_err(&mhi_ep_lb_work->mdev->dev, "Failed to send the packet\n");
+ kfree_skb(mhi_ep_lb_work->skb);
+ }
+
+ kfree(mhi_ep_lb_work);
+}
+
+static void mhi_ep_loopback_ul_callback(struct mhi_ep_device *mhi_dev,
+ struct mhi_result *mhi_res)
+{
+ struct mhi_ep_loopback *mhi_ep_lb = dev_get_drvdata(&mhi_dev->dev);
+ struct mhi_ep_loopback_work *mhi_ep_lb_work;
+ struct sk_buff *skb;
+
+ if (!(mhi_res->transaction_status)) {
+ skb = alloc_skb(mhi_res->bytes_xferd, GFP_KERNEL);
+ if (!skb) {
+ dev_err(&mhi_dev->dev, "Failed to allocate skb\n");
+ return;
+ }
+
+ skb_put_data(skb, mhi_res->buf_addr, mhi_res->bytes_xferd);
+
+ mhi_ep_lb_work = kmalloc(sizeof(*mhi_ep_lb_work), GFP_KERNEL);
+ if (!mhi_ep_lb_work) {
+ dev_err(&mhi_dev->dev, "Unable to allocate the work structure\n");
+ kfree_skb(skb);
+ return;
+ }
+
+ INIT_WORK(&mhi_ep_lb_work->work, mhi_ep_loopback_work_handler);
+ mhi_ep_lb_work->mdev = mhi_dev;
+ mhi_ep_lb_work->skb = skb;
+
+ queue_work(mhi_ep_lb->loopback_wq, &mhi_ep_lb_work->work);
+ }
+}
+
+static void mhi_ep_loopback_dl_callback(struct mhi_ep_device *mhi_dev,
+ struct mhi_result *mhi_res)
+{
+ struct sk_buff *skb;
+
+ if (mhi_res->transaction_status)
+ return;
+
+ skb = mhi_res->buf_addr;
+ if (skb)
+ kfree_skb(skb);
+}
+
+static int mhi_ep_loopback_probe(struct mhi_ep_device *mhi_dev, const struct mhi_device_id *id)
+{
+ struct mhi_ep_loopback *mhi_ep_lb;
+
+ mhi_ep_lb = devm_kzalloc(&mhi_dev->dev, sizeof(struct mhi_ep_loopback), GFP_KERNEL);
+ if (!mhi_ep_lb)
+ return -ENOMEM;
+
+ mhi_ep_lb->loopback_wq = alloc_ordered_workqueue("mhi_loopback", WQ_MEM_RECLAIM);
+ if (!mhi_ep_lb->loopback_wq) {
+ dev_err(&mhi_dev->dev, "Failed to create workqueue.\n");
+ return -ENOMEM;
+ }
+
+ mhi_ep_lb->mdev = mhi_dev;
+ dev_set_drvdata(&mhi_dev->dev, mhi_ep_lb);
+
+ return 0;
+}
+
+static void mhi_ep_loopback_remove(struct mhi_ep_device *mhi_dev)
+{
+ struct mhi_ep_loopback *mhi_ep_lb = dev_get_drvdata(&mhi_dev->dev);
+
+ destroy_workqueue(mhi_ep_lb->loopback_wq);
+ dev_set_drvdata(&mhi_dev->dev, NULL);
+}
+
+static const struct mhi_device_id mhi_ep_loopback_id_table[] = {
+ { .chan = "LOOPBACK"},
+ {}
+};
+MODULE_DEVICE_TABLE(mhi, mhi_ep_loopback_id_table);
+
+static struct mhi_ep_driver mhi_ep_loopback_driver = {
+ .probe = mhi_ep_loopback_probe,
+ .remove = mhi_ep_loopback_remove,
+ .dl_xfer_cb = mhi_ep_loopback_dl_callback,
+ .ul_xfer_cb = mhi_ep_loopback_ul_callback,
+ .id_table = mhi_ep_loopback_id_table,
+ .driver = {
+ .name = "mhi_ep_loopback",
+ .owner = THIS_MODULE,
+ },
+};
+
+module_mhi_ep_driver(mhi_ep_loopback_driver);
+
+MODULE_AUTHOR("Krishna chaitanya chundru <krishna.chundru@....qualcomm.com>");
+MODULE_AUTHOR("Sumit Kumar <sumit.kumar@....qualcomm.com>");
+MODULE_DESCRIPTION("MHI Endpoint Loopback driver");
+MODULE_LICENSE("GPL");
--
2.34.1
Powered by blists - more mailing lists