[PATCH v12 0/5] userspace MHI client interface driver

[PATCH v12 0/5] userspace MHI client interface driver

[Hemant Kumar]

This patch series adds support for UCI driver. UCI driver enables userspace
clients to communicate to external MHI devices like modem and WLAN. UCI driver
probe creates standard character device file nodes for userspace clients to
perform open, read, write, poll and release file operations. These file
operations call MHI core layer APIs to perform data transfer using MHI bus
to communicate with MHI device. It also adds a loopback test application to
verify the UCI LOOPBACK channel. Patch is tested using arm64 based platform.

V12:
- Added loopback test driver under selftest/drivers/mhi. Updated kernel
  documentation for the usage of the loopback test application.
- Addressed review comments for renaming variable names, updated inline
  comments and removed two redundant dev_dbg.

V11:
- Fixed review comments for UCI documentation by expanding TLAs and rewording
  some sentences.

V10:
- Replaced mutex_lock with mutex_lock_interruptible in read() and write() file
  ops call back.

V9:
- Renamed dl_lock to dl_pending _lock and pending list to dl_pending for
  clarity.
- Used read lock to protect cur_buf.
- Change transfer status check logic and only consider 0 and -EOVERFLOW as
  only success.
- Added __int to module init function.
- Print channel name instead of minor number upon successful probe.

V8:
- Fixed kernel test robot compilation error by changing %lu to %zu for
  size_t.
- Replaced uci with UCI in Kconfig, commit text, and comments in driver
  code.
- Fixed minor style related comments.

V7:
- Decoupled uci device and uci channel objects. uci device is
  associated with device file node. uci channel is associated
  with MHI channels. uci device refers to uci channel to perform
  MHI channel operations for device file operations like read()
  and write(). uci device increments its reference count for
  every open(). uci device calls mhi_uci_dev_start_chan() to start
  the MHI channel. uci channel object is tracking number of times
  MHI channel is referred. This allows to keep the MHI channel in
  start state until last release() is called. After that uci channel
  reference count goes to 0 and uci channel clean up is performed
  which stops the MHI channel. After the last call to release() if
  driver is removed uci reference count becomes 0 and uci object is
  cleaned up.
- Use separate uci channel read and write lock to fine grain locking
  between reader and writer.
- Use uci device lock to synchronize open, release and driver remove.
- Optimize for downlink only or uplink only UCI device.

V6:
- Moved uci.c to mhi directory.
- Updated Kconfig to add module information.
- Updated Makefile to rename uci object file name as mhi_uci
- Removed kref for open count

V5:
- Removed mhi_uci_drv structure.
- Used idr instead of creating global list of uci devices.
- Used kref instead of local ref counting for uci device and
  open count.
- Removed unlikely macro.

V4:
- Fix locking to protect proper struct members.
- Updated documentation describing uci client driver use cases.
- Fixed uci ref counting in mhi_uci_open for error case.
- Addressed style related review comments.

V3: Added documentation for MHI UCI driver.

V2:
- Added mutex lock to prevent multiple readers to access same
- mhi buffer which can result into use after free.

Hemant Kumar (5):
  bus: mhi: core: Add helper API to return number of free TREs
  bus: mhi: core: Move MHI_MAX_MTU to external header file
  docs: Add documentation for userspace client interface
  bus: mhi: Add userspace client interface driver
  selftest: mhi: Add support to test MHI LOOPBACK channel

 Documentation/mhi/index.rst                        |   1 +
 Documentation/mhi/uci.rst                          | 109 +++
 drivers/bus/mhi/Kconfig                            |  13 +
 drivers/bus/mhi/Makefile                           |   3 +
 drivers/bus/mhi/core/internal.h                    |   1 -
 drivers/bus/mhi/core/main.c                        |  12 +
 drivers/bus/mhi/uci.c                              | 667 +++++++++++++++++
 include/linux/mhi.h                                |  12 +
 tools/testing/selftests/Makefile                   |   1 +
 tools/testing/selftests/drivers/.gitignore         |   1 +
 tools/testing/selftests/drivers/mhi/Makefile       |   8 +
 tools/testing/selftests/drivers/mhi/config         |   2 +
 .../testing/selftests/drivers/mhi/loopback_test.c  | 789 +++++++++++++++++++++
 13 files changed, 1618 insertions(+), 1 deletion(-)
 create mode 100644 Documentation/mhi/uci.rst
 create mode 100644 drivers/bus/mhi/uci.c
 create mode 100644 tools/testing/selftests/drivers/mhi/Makefile
 create mode 100644 tools/testing/selftests/drivers/mhi/config
 create mode 100644 tools/testing/selftests/drivers/mhi/loopback_test.c

-- 
The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum,
a Linux Foundation Collaborative Project

[PATCH v12 1/5] bus: mhi: core: Add helper API to return number of free TREs

[Hemant Kumar]

Introduce mhi_get_free_desc_count() API to return number
of TREs available to queue buffer. MHI clients can use this
API to know before hand if ring is full without calling queue
API.

Signed-off-by: Hemant Kumar <hemantk@codeaurora.org>
Reviewed-by: Jeffrey Hugo <jhugo@codeaurora.org>
Reviewed-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
---
 drivers/bus/mhi/core/main.c | 12 ++++++++++++
 include/linux/mhi.h         |  9 +++++++++
 2 files changed, 21 insertions(+)

diff --git a/drivers/bus/mhi/core/main.c b/drivers/bus/mhi/core/main.c
index f953e2a..6158720 100644
--- a/drivers/bus/mhi/core/main.c
+++ b/drivers/bus/mhi/core/main.c
@@ -260,6 +260,18 @@ int mhi_destroy_device(struct device *dev, void *data)
 	return 0;
 }
 
+int mhi_get_free_desc_count(struct mhi_device *mhi_dev,
+				enum dma_data_direction dir)
+{
+	struct mhi_controller *mhi_cntrl = mhi_dev->mhi_cntrl;
+	struct mhi_chan *mhi_chan = (dir == DMA_TO_DEVICE) ?
+		mhi_dev->ul_chan : mhi_dev->dl_chan;
+	struct mhi_ring *tre_ring = &mhi_chan->tre_ring;
+
+	return get_nr_avail_ring_elements(mhi_cntrl, tre_ring);
+}
+EXPORT_SYMBOL_GPL(mhi_get_free_desc_count);
+
 void mhi_notify(struct mhi_device *mhi_dev, enum mhi_callback cb_reason)
 {
 	struct mhi_driver *mhi_drv;
diff --git a/include/linux/mhi.h b/include/linux/mhi.h
index 52b3c60..a4d0f48 100644
--- a/include/linux/mhi.h
+++ b/include/linux/mhi.h
@@ -597,6 +597,15 @@ void mhi_set_mhi_state(struct mhi_controller *mhi_cntrl,
 void mhi_notify(struct mhi_device *mhi_dev, enum mhi_callback cb_reason);
 
 /**
+ * mhi_get_free_desc_count - Get transfer ring length
+ * Get # of TD available to queue buffers
+ * @mhi_dev: Device associated with the channels
+ * @dir: Direction of the channel
+ */
+int mhi_get_free_desc_count(struct mhi_device *mhi_dev,
+				enum dma_data_direction dir);
+
+/**
  * mhi_prepare_for_power_up - Do pre-initialization before power up.
  *                            This is optional, call this before power up if
  *                            the controller does not want bus framework to
-- 
The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum,
a Linux Foundation Collaborative Project

Re: [PATCH v12 1/5] bus: mhi: core: Add helper API to return number of free TREs

[Loic Poulain]

On Mon, 16 Nov 2020 at 23:46, Hemant Kumar <hemantk@codeaurora.org> wrote:
>
> Introduce mhi_get_free_desc_count() API to return number
> of TREs available to queue buffer. MHI clients can use this
> API to know before hand if ring is full without calling queue
> API.
>
> Signed-off-by: Hemant Kumar <hemantk@codeaurora.org>
> Reviewed-by: Jeffrey Hugo <jhugo@codeaurora.org>
> Reviewed-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>

In case this series get new comments to address, I would suggest
merging that patch in mhi-next separately so that other drivers can
start benefiting this function (I would like to use it in mhi-net).

Regards,
Loic

Re: [PATCH v12 1/5] bus: mhi: core: Add helper API to return number of free TREs

[Manivannan Sadhasivam]

On Wed, Nov 18, 2020 at 10:32:45AM +0100, Loic Poulain wrote:
> On Mon, 16 Nov 2020 at 23:46, Hemant Kumar <hemantk@codeaurora.org> wrote:
> >
> > Introduce mhi_get_free_desc_count() API to return number
> > of TREs available to queue buffer. MHI clients can use this
> > API to know before hand if ring is full without calling queue
> > API.
> >
> > Signed-off-by: Hemant Kumar <hemantk@codeaurora.org>
> > Reviewed-by: Jeffrey Hugo <jhugo@codeaurora.org>
> > Reviewed-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
> 
> In case this series get new comments to address, I would suggest
> merging that patch in mhi-next separately so that other drivers can
> start benefiting this function (I would like to use it in mhi-net).
> 

Greg doesn't like that. He asked me to pick APIs only when there an in-tree
consumer available.

Thanks,
Mani

> Regards,
> Loic

Re: [PATCH v12 1/5] bus: mhi: core: Add helper API to return number of free TREs

[Greg Kroah-Hartman]

On Sat, Nov 28, 2020 at 11:59:46AM +0530, Manivannan Sadhasivam wrote:
> On Wed, Nov 18, 2020 at 10:32:45AM +0100, Loic Poulain wrote:
> > On Mon, 16 Nov 2020 at 23:46, Hemant Kumar <hemantk@codeaurora.org> wrote:
> > >
> > > Introduce mhi_get_free_desc_count() API to return number
> > > of TREs available to queue buffer. MHI clients can use this
> > > API to know before hand if ring is full without calling queue
> > > API.
> > >
> > > Signed-off-by: Hemant Kumar <hemantk@codeaurora.org>
> > > Reviewed-by: Jeffrey Hugo <jhugo@codeaurora.org>
> > > Reviewed-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
> > 
> > In case this series get new comments to address, I would suggest
> > merging that patch in mhi-next separately so that other drivers can
> > start benefiting this function (I would like to use it in mhi-net).
> > 
> 
> Greg doesn't like that. He asked me to pick APIs only when there an in-tree
> consumer available.

If someone wants to use it, then yes, by all means merge it.  I can't
just take new apis without any user.

thanks,

greg k-h

[PATCH v12 2/5] bus: mhi: core: Move MHI_MAX_MTU to external header file

[Hemant Kumar]

Currently this macro is defined in internal MHI header as
a TRE length mask. Moving it to external header allows MHI
client drivers to set this upper bound for the transmit
buffer size.

Signed-off-by: Hemant Kumar <hemantk@codeaurora.org>
Reviewed-by: Jeffrey Hugo <jhugo@codeaurora.org>
Reviewed-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
---
 drivers/bus/mhi/core/internal.h | 1 -
 include/linux/mhi.h             | 3 +++
 2 files changed, 3 insertions(+), 1 deletion(-)

diff --git a/drivers/bus/mhi/core/internal.h b/drivers/bus/mhi/core/internal.h
index 2df8de5..7d1f8bc 100644
--- a/drivers/bus/mhi/core/internal.h
+++ b/drivers/bus/mhi/core/internal.h
@@ -453,7 +453,6 @@ enum mhi_pm_state {
 #define CMD_EL_PER_RING			128
 #define PRIMARY_CMD_RING		0
 #define MHI_DEV_WAKE_DB			127
-#define MHI_MAX_MTU			0xffff
 #define MHI_RANDOM_U32_NONZERO(bmsk)	(prandom_u32_max(bmsk) + 1)
 
 enum mhi_er_type {
diff --git a/include/linux/mhi.h b/include/linux/mhi.h
index a4d0f48..53bb41d 100644
--- a/include/linux/mhi.h
+++ b/include/linux/mhi.h
@@ -15,6 +15,9 @@
 #include <linux/wait.h>
 #include <linux/workqueue.h>
 
+/* MHI client drivers to set this upper bound for tx buffer */
+#define MHI_MAX_MTU 0xffff
+
 #define MHI_MAX_OEM_PK_HASH_SEGMENTS 16
 
 struct mhi_chan;
-- 
The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum,
a Linux Foundation Collaborative Project

[PATCH v12 3/5] docs: Add documentation for userspace client interface

[Hemant Kumar]

MHI userspace client driver is creating device file node
for user application to perform file operations. File
operations are handled by MHI core driver. Currently
Loopback MHI channel is supported by this driver.

Signed-off-by: Hemant Kumar <hemantk@codeaurora.org>
---
 Documentation/mhi/index.rst |  1 +
 Documentation/mhi/uci.rst   | 86 +++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 87 insertions(+)
 create mode 100644 Documentation/mhi/uci.rst

diff --git a/Documentation/mhi/index.rst b/Documentation/mhi/index.rst
index 1d8dec3..c75a371 100644
--- a/Documentation/mhi/index.rst
+++ b/Documentation/mhi/index.rst
@@ -9,6 +9,7 @@ MHI
 
    mhi
    topology
+   uci
 
 .. only::  subproject and html
 
diff --git a/Documentation/mhi/uci.rst b/Documentation/mhi/uci.rst
new file mode 100644
index 0000000..ce8740e
--- /dev/null
+++ b/Documentation/mhi/uci.rst
@@ -0,0 +1,86 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+=================================
+Userspace Client Interface (UCI)
+=================================
+
+UCI driver enables userspace clients to communicate to external MHI devices
+like modem and WLAN. UCI driver probe creates standard character device file
+nodes for userspace clients to perform open, read, write, poll and release file
+operations. UCI device object represents UCI device file node which gets
+instantiated as part of MHI UCI driver probe. UCI channel object represents
+MHI uplink or downlink channel.
+
+Operations
+==========
+
+open
+----
+
+Instantiates UCI channel object and starts MHI channels to move it to running
+state. Inbound buffers are queued to downlink channel transfer ring. Every
+subsequent open() increments UCI device reference count as well as UCI channel
+reference count.
+
+read
+----
+
+When data transfer is completed on downlink channel, transfer ring element
+buffer is copied to pending list. Reader is unblocked and data is copied to
+userspace buffer. Transfer ring element buffer is queued back to downlink
+channel transfer ring.
+
+write
+-----
+
+Write buffer is queued to uplink channel transfer ring if ring is not full. Upon
+uplink transfer completion buffer is freed.
+
+poll
+----
+
+Returns EPOLLIN | EPOLLRDNORM mask if pending list has buffers to be read by
+userspace. Returns EPOLLOUT | EPOLLWRNORM mask if MHI uplink channel transfer
+ring is not empty. Returns EPOLLERR when UCI driver is removed.
+
+release
+-------
+
+Decrements UCI device reference count and UCI channel reference count upon last
+release(). UCI channel clean up is performed. MHI channel moves to disable
+state and inbound buffers are freed.
+
+Usage
+=====
+
+Device file node is created with format:-
+
+/dev/mhi_<controller_name>_<mhi_device_name>
+
+controller_name is the name of underlying bus used to transfer data. mhi_device
+name is the name of the MHI channel being used by MHI client in userspace to
+send or receive data using MHI protocol.
+
+There is a separate character device file node created for each channel
+specified in MHI device id table. MHI channels are statically defined by MHI
+specification. The list of supported channels is in the channel list variable
+of mhi_device_id table in UCI driver.
+
+LOOPBACK Channel
+----------------
+
+Userspace MHI client using LOOPBACK channel opens device file node. As part of
+open operation transfer ring elements are queued to transfer ring of LOOPBACK
+channel 1 and channel doorbell is rung. When userspace MHI client performs write
+operation on device node, data buffer gets queued as part of transfer ring
+element to transfer ring of LOOPBACK channel 0. MHI Core driver rings the
+channel doorbell for MHI device to move data over underlying bus. When userspace
+MHI client driver performs read operation, same data gets looped back to MHI
+host using LOOPBACK channel 1. LOOPBACK channel is used to verify data path
+and data integrity between MHI Host and MHI device.
+
+Other Use Cases
+---------------
+
+Getting MHI device specific diagnostics information to userspace MHI diagnostic
+client using DIAG channel 4 (Host to device) and 5 (Device to Host).
-- 
The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum,
a Linux Foundation Collaborative Project

[PATCH v12 4/5] bus: mhi: Add userspace client interface driver

[Hemant Kumar]

This MHI client driver allows userspace clients to transfer
raw data between MHI device and host using standard file operations.
Driver instantiates UCI device object which is associated to device
file node. UCI device object instantiates UCI channel object when device
file node is opened. UCI channel object is used to manage MHI channels
by calling MHI core APIs for read and write operations. MHI channels
are started as part of device open(). MHI channels remain in start
state until last release() is called on UCI device file node. Device
file node is created with format

/dev/mhi_<controller_name>_<mhi_device_name>

Currently it supports LOOPBACK channel.

Signed-off-by: Hemant Kumar <hemantk@codeaurora.org>
---
 drivers/bus/mhi/Kconfig  |  13 +
 drivers/bus/mhi/Makefile |   3 +
 drivers/bus/mhi/uci.c    | 667 +++++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 683 insertions(+)
 create mode 100644 drivers/bus/mhi/uci.c

diff --git a/drivers/bus/mhi/Kconfig b/drivers/bus/mhi/Kconfig
index da5cd0c..5194e8e 100644
--- a/drivers/bus/mhi/Kconfig
+++ b/drivers/bus/mhi/Kconfig
@@ -29,3 +29,16 @@ config MHI_BUS_PCI_GENERIC
 	  This driver provides MHI PCI controller driver for devices such as
 	  Qualcomm SDX55 based PCIe modems.
 
+config MHI_UCI
+	tristate "MHI UCI"
+	depends on MHI_BUS
+	help
+	  MHI based Userspace Client Interface (UCI) driver is used for
+	  transferring raw data between host and device using standard file
+	  operations from userspace. Open, read, write, poll and close
+	  operations are supported by this driver. Please check
+	  mhi_uci_match_table for all supported channels that are exposed to
+	  userspace.
+
+	  To compile this driver as a module, choose M here: the module will be
+	  called mhi_uci.
diff --git a/drivers/bus/mhi/Makefile b/drivers/bus/mhi/Makefile
index 0a2d778..69f2111 100644
--- a/drivers/bus/mhi/Makefile
+++ b/drivers/bus/mhi/Makefile
@@ -4,3 +4,6 @@ obj-y += core/
 obj-$(CONFIG_MHI_BUS_PCI_GENERIC) += mhi_pci_generic.o
 mhi_pci_generic-y += pci_generic.o
 
+# MHI client
+mhi_uci-y := uci.o
+obj-$(CONFIG_MHI_UCI) += mhi_uci.o
diff --git a/drivers/bus/mhi/uci.c b/drivers/bus/mhi/uci.c
new file mode 100644
index 0000000..75b0831
--- /dev/null
+++ b/drivers/bus/mhi/uci.c
@@ -0,0 +1,667 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/* Copyright (c) 2018-2020, The Linux Foundation. All rights reserved.*/
+
+#include <linux/kernel.h>
+#include <linux/mhi.h>
+#include <linux/mod_devicetable.h>
+#include <linux/module.h>
+#include <linux/poll.h>
+
+#define MHI_DEVICE_NAME "mhi"
+#define MHI_UCI_DRIVER_NAME "mhi_uci"
+#define MHI_MAX_UCI_MINORS 128
+
+static DEFINE_IDR(uci_idr);
+static DEFINE_MUTEX(uci_drv_mutex);
+static struct class *uci_dev_class;
+static int uci_dev_major;
+
+/**
+ * struct uci_chan - MHI channel for a UCI device
+ * @udev: associated UCI device object
+ * @ul_wq: wait queue for writer
+ * @write_lock: mutex write lock for ul channel
+ * @dl_wq: wait queue for reader
+ * @read_lock: mutex read lock for dl channel
+ * @dl_pending_lock: spin lock for dl_pending list
+ * @dl_pending: list of dl buffers userspace is waiting to read
+ * @cur_buf: current buffer userspace is reading
+ * @dl_size: size of the current dl buffer userspace is reading
+ * @ref_count: uci_chan reference count
+ */
+struct uci_chan {
+	struct uci_dev *udev;
+	wait_queue_head_t ul_wq;
+
+	/* ul channel lock to synchronize multiple writes */
+	struct mutex write_lock;
+
+	wait_queue_head_t dl_wq;
+
+	/* dl channel lock to synchronize multiple reads */
+	struct mutex read_lock;
+
+	/*
+	 * protects pending list in bh context, channel release, read and
+	 * poll
+	 */
+	spinlock_t dl_pending_lock;
+
+	struct list_head dl_pending;
+	struct uci_buf *cur_buf;
+	size_t dl_size;
+	struct kref ref_count;
+};
+
+/**
+ * struct uci_buf - UCI buffer
+ * @data: data buffer
+ * @len: length of data buffer
+ * @node: list node of the UCI buffer
+ */
+struct uci_buf {
+	void *data;
+	size_t len;
+	struct list_head node;
+};
+
+/**
+ * struct uci_dev - MHI UCI device
+ * @minor: UCI device node minor number
+ * @mhi_dev: associated mhi device object
+ * @uchan: UCI uplink and downlink channel object
+ * @mtu: max TRE buffer length
+ * @enabled: Flag to track the state of the UCI device
+ * @lock: mutex lock to manage uchan object
+ * @ref_count: uci_dev reference count
+ */
+struct uci_dev {
+	unsigned int minor;
+	struct mhi_device *mhi_dev;
+	struct uci_chan *uchan;
+	size_t mtu;
+	bool enabled;
+
+	/* synchronize open, release and driver remove */
+	struct mutex lock;
+	struct kref ref_count;
+};
+
+static void mhi_uci_dev_chan_release(struct kref *ref)
+{
+	struct uci_buf *buf_itr, *tmp;
+	struct uci_chan *uchan =
+		container_of(ref, struct uci_chan, ref_count);
+
+	if (uchan->udev->enabled)
+		mhi_unprepare_from_transfer(uchan->udev->mhi_dev);
+
+	spin_lock_bh(&uchan->dl_pending_lock);
+	list_for_each_entry_safe(buf_itr, tmp, &uchan->dl_pending, node) {
+		list_del(&buf_itr->node);
+		kfree(buf_itr->data);
+	}
+	spin_unlock_bh(&uchan->dl_pending_lock);
+
+	wake_up(&uchan->ul_wq);
+	wake_up(&uchan->dl_wq);
+
+	mutex_lock(&uchan->read_lock);
+	if (uchan->cur_buf)
+		kfree(uchan->cur_buf->data);
+
+	uchan->cur_buf = NULL;
+	mutex_unlock(&uchan->read_lock);
+
+	mutex_destroy(&uchan->write_lock);
+	mutex_destroy(&uchan->read_lock);
+
+	uchan->udev->uchan = NULL;
+	kfree(uchan);
+}
+
+static int mhi_queue_inbound(struct uci_dev *udev)
+{
+	struct mhi_device *mhi_dev = udev->mhi_dev;
+	struct device *dev = &mhi_dev->dev;
+	int nr_desc, i, ret = -EIO;
+	size_t dl_buf_size;
+	void *buf;
+	struct uci_buf *ubuf;
+
+	/*
+	 * skip queuing without error if dl channel is not supported. This
+	 * allows open to succeed for udev, supporting ul only channel.
+	 */
+	if (!udev->mhi_dev->dl_chan)
+		return 0;
+
+	nr_desc = mhi_get_free_desc_count(mhi_dev, DMA_FROM_DEVICE);
+
+	for (i = 0; i < nr_desc; i++) {
+		buf = kmalloc(udev->mtu, GFP_KERNEL);
+		if (!buf)
+			return -ENOMEM;
+
+		dl_buf_size = udev->mtu - sizeof(*ubuf);
+
+		/* save uci_buf info at the end of buf */
+		ubuf = buf + dl_buf_size;
+		ubuf->data = buf;
+
+		dev_dbg(dev, "Allocated buf %d of %d size %zu\n", i, nr_desc,
+			dl_buf_size);
+
+		ret = mhi_queue_buf(mhi_dev, DMA_FROM_DEVICE, buf, dl_buf_size,
+				    MHI_EOT);
+		if (ret) {
+			kfree(buf);
+			dev_err(dev, "Failed to queue buffer %d\n", i);
+			return ret;
+		}
+	}
+
+	return ret;
+}
+
+static int mhi_uci_dev_start_chan(struct uci_dev *udev)
+{
+	int ret = 0;
+	struct uci_chan *uchan;
+
+	mutex_lock(&udev->lock);
+	if (!udev->uchan || !kref_get_unless_zero(&udev->uchan->ref_count)) {
+		uchan = kzalloc(sizeof(*uchan), GFP_KERNEL);
+		if (!uchan) {
+			ret = -ENOMEM;
+			goto error_chan_start;
+		}
+
+		udev->uchan = uchan;
+		uchan->udev = udev;
+		init_waitqueue_head(&uchan->ul_wq);
+		init_waitqueue_head(&uchan->dl_wq);
+		mutex_init(&uchan->write_lock);
+		mutex_init(&uchan->read_lock);
+		spin_lock_init(&uchan->dl_pending_lock);
+		INIT_LIST_HEAD(&uchan->dl_pending);
+
+		ret = mhi_prepare_for_transfer(udev->mhi_dev);
+		if (ret) {
+			dev_err(&udev->mhi_dev->dev, "Error starting transfer channels\n");
+			goto error_chan_cleanup;
+		}
+
+		ret = mhi_queue_inbound(udev);
+		if (ret)
+			goto error_chan_cleanup;
+
+		kref_init(&uchan->ref_count);
+	}
+
+	mutex_unlock(&udev->lock);
+
+	return 0;
+
+error_chan_cleanup:
+	mhi_uci_dev_chan_release(&uchan->ref_count);
+error_chan_start:
+	mutex_unlock(&udev->lock);
+	return ret;
+}
+
+static void mhi_uci_dev_release(struct kref *ref)
+{
+	struct uci_dev *udev =
+		container_of(ref, struct uci_dev, ref_count);
+
+	mutex_destroy(&udev->lock);
+
+	kfree(udev);
+}
+
+static int mhi_uci_open(struct inode *inode, struct file *filp)
+{
+	unsigned int minor = iminor(inode);
+	struct uci_dev *udev = NULL;
+	int ret;
+
+	mutex_lock(&uci_drv_mutex);
+	udev = idr_find(&uci_idr, minor);
+	if (!udev) {
+		pr_debug("uci dev: minor %d not found\n", minor);
+		mutex_unlock(&uci_drv_mutex);
+		return -ENODEV;
+	}
+
+	kref_get(&udev->ref_count);
+	mutex_unlock(&uci_drv_mutex);
+
+	ret = mhi_uci_dev_start_chan(udev);
+	if (ret) {
+		kref_put(&udev->ref_count, mhi_uci_dev_release);
+		return ret;
+	}
+
+	filp->private_data = udev;
+
+	return 0;
+}
+
+static int mhi_uci_release(struct inode *inode, struct file *file)
+{
+	struct uci_dev *udev = file->private_data;
+
+	mutex_lock(&udev->lock);
+	kref_put(&udev->uchan->ref_count, mhi_uci_dev_chan_release);
+	mutex_unlock(&udev->lock);
+
+	kref_put(&udev->ref_count, mhi_uci_dev_release);
+
+	return 0;
+}
+
+static __poll_t mhi_uci_poll(struct file *file, poll_table *wait)
+{
+	struct uci_dev *udev = file->private_data;
+	struct mhi_device *mhi_dev = udev->mhi_dev;
+	struct device *dev = &mhi_dev->dev;
+	struct uci_chan *uchan = udev->uchan;
+	__poll_t mask = 0;
+
+	poll_wait(file, &udev->uchan->ul_wq, wait);
+	poll_wait(file, &udev->uchan->dl_wq, wait);
+
+	if (!udev->enabled) {
+		mask = EPOLLERR;
+		goto done;
+	}
+
+	spin_lock_bh(&uchan->dl_pending_lock);
+	if (!list_empty(&uchan->dl_pending) || uchan->cur_buf)
+		mask |= EPOLLIN | EPOLLRDNORM;
+	spin_unlock_bh(&uchan->dl_pending_lock);
+
+	if (mhi_get_free_desc_count(mhi_dev, DMA_TO_DEVICE) > 0)
+		mask |= EPOLLOUT | EPOLLWRNORM;
+
+	dev_dbg(dev, "Client attempted to poll, returning mask 0x%x\n", mask);
+
+done:
+	return mask;
+}
+
+static ssize_t mhi_uci_write(struct file *file,
+			     const char __user *buf,
+			     size_t count,
+			     loff_t *offp)
+{
+	struct uci_dev *udev = file->private_data;
+	struct mhi_device *mhi_dev = udev->mhi_dev;
+	struct device *dev = &mhi_dev->dev;
+	struct uci_chan *uchan = udev->uchan;
+	size_t bytes_xfered = 0;
+	int ret, nr_desc = 0;
+
+	/* if ul channel is not supported return error */
+	if (!mhi_dev->ul_chan)
+		return -EOPNOTSUPP;
+
+	if (!buf || !count)
+		return -EINVAL;
+
+	dev_dbg(dev, "%s: to xfer: %zu bytes\n", __func__, count);
+
+	if (mutex_lock_interruptible(&uchan->write_lock))
+		return -EINTR;
+
+	while (count) {
+		size_t xfer_size;
+		void *kbuf;
+		enum mhi_flags flags;
+
+		/* wait for free descriptors */
+		ret = wait_event_interruptible(uchan->ul_wq,
+					       (!udev->enabled) ||
+				(nr_desc = mhi_get_free_desc_count(mhi_dev,
+					       DMA_TO_DEVICE)) > 0);
+
+		if (ret == -ERESTARTSYS) {
+			dev_dbg(dev, "Interrupted by a signal in %s, exiting\n",
+				__func__);
+			goto err_mtx_unlock;
+		}
+
+		if (!udev->enabled) {
+			ret = -ENODEV;
+			goto err_mtx_unlock;
+		}
+
+		xfer_size = min_t(size_t, count, udev->mtu);
+		kbuf = kmalloc(xfer_size, GFP_KERNEL);
+		if (!kbuf) {
+			ret = -ENOMEM;
+			goto err_mtx_unlock;
+		}
+
+		ret = copy_from_user(kbuf, buf, xfer_size);
+		if (ret) {
+			kfree(kbuf);
+			ret = -EFAULT;
+			goto err_mtx_unlock;
+		}
+
+		/* if ring is full after this force EOT */
+		if (nr_desc > 1 && (count - xfer_size))
+			flags = MHI_CHAIN;
+		else
+			flags = MHI_EOT;
+
+		ret = mhi_queue_buf(mhi_dev, DMA_TO_DEVICE, kbuf, xfer_size,
+				    flags);
+		if (ret) {
+			kfree(kbuf);
+			goto err_mtx_unlock;
+		}
+
+		bytes_xfered += xfer_size;
+		count -= xfer_size;
+		buf += xfer_size;
+	}
+
+	mutex_unlock(&uchan->write_lock);
+	dev_dbg(dev, "%s: bytes xferred: %zu\n", __func__, bytes_xfered);
+
+	return bytes_xfered;
+
+err_mtx_unlock:
+	mutex_unlock(&uchan->write_lock);
+
+	return ret;
+}
+
+static ssize_t mhi_uci_read(struct file *file,
+			    char __user *buf,
+			    size_t count,
+			    loff_t *ppos)
+{
+	struct uci_dev *udev = file->private_data;
+	struct mhi_device *mhi_dev = udev->mhi_dev;
+	struct uci_chan *uchan = udev->uchan;
+	struct device *dev = &mhi_dev->dev;
+	struct uci_buf *ubuf;
+	size_t rx_buf_size;
+	char *ptr;
+	size_t to_copy;
+	int ret = 0;
+
+	/* if dl channel is not supported return error */
+	if (!mhi_dev->dl_chan)
+		return -EOPNOTSUPP;
+
+	if (!buf)
+		return -EINVAL;
+
+	if (mutex_lock_interruptible(&uchan->read_lock))
+		return -EINTR;
+
+	spin_lock_bh(&uchan->dl_pending_lock);
+	/* No data available to read, wait */
+	if (!uchan->cur_buf && list_empty(&uchan->dl_pending)) {
+		dev_dbg(dev, "No data available to read, waiting\n");
+
+		spin_unlock_bh(&uchan->dl_pending_lock);
+		ret = wait_event_interruptible(uchan->dl_wq,
+					       (!udev->enabled ||
+					      !list_empty(&uchan->dl_pending)));
+
+		if (ret == -ERESTARTSYS) {
+			dev_dbg(dev, "Interrupted by a signal in %s, exiting\n",
+				__func__);
+			goto err_mtx_unlock;
+		}
+
+		if (!udev->enabled) {
+			ret = -ENODEV;
+			goto err_mtx_unlock;
+		}
+		spin_lock_bh(&uchan->dl_pending_lock);
+	}
+
+	/* new read, get the next descriptor from the list */
+	if (!uchan->cur_buf) {
+		ubuf = list_first_entry_or_null(&uchan->dl_pending,
+						struct uci_buf, node);
+		if (!ubuf) {
+			ret = -EIO;
+			goto err_spin_unlock;
+		}
+
+		list_del(&ubuf->node);
+		uchan->cur_buf = ubuf;
+		uchan->dl_size = ubuf->len;
+		dev_dbg(dev, "Got pkt of size: %zu\n", uchan->dl_size);
+	}
+	spin_unlock_bh(&uchan->dl_pending_lock);
+
+	ubuf = uchan->cur_buf;
+
+	/* Copy the buffer to user space */
+	to_copy = min_t(size_t, count, uchan->dl_size);
+	ptr = ubuf->data + (ubuf->len - uchan->dl_size);
+
+	ret = copy_to_user(buf, ptr, to_copy);
+	if (ret) {
+		ret = -EFAULT;
+		goto err_mtx_unlock;
+	}
+
+	dev_dbg(dev, "Copied %zu of %zu bytes\n", to_copy, uchan->dl_size);
+	uchan->dl_size -= to_copy;
+
+	/* we finished with this buffer, queue it back to hardware */
+	if (!uchan->dl_size) {
+		uchan->cur_buf = NULL;
+
+		rx_buf_size = udev->mtu - sizeof(*ubuf);
+		ret = mhi_queue_buf(mhi_dev, DMA_FROM_DEVICE, ubuf->data,
+				    rx_buf_size, MHI_EOT);
+		if (ret) {
+			dev_err(dev, "Failed to recycle element: %d\n", ret);
+			kfree(ubuf->data);
+			goto err_mtx_unlock;
+		}
+	}
+	mutex_unlock(&uchan->read_lock);
+
+	dev_dbg(dev, "%s: Returning %zu bytes\n", __func__, to_copy);
+
+	return to_copy;
+
+err_spin_unlock:
+	spin_unlock_bh(&uchan->dl_pending_lock);
+err_mtx_unlock:
+	mutex_unlock(&uchan->read_lock);
+	return ret;
+}
+
+static const struct file_operations mhidev_fops = {
+	.owner = THIS_MODULE,
+	.open = mhi_uci_open,
+	.release = mhi_uci_release,
+	.read = mhi_uci_read,
+	.write = mhi_uci_write,
+	.poll = mhi_uci_poll,
+};
+
+static void mhi_ul_xfer_cb(struct mhi_device *mhi_dev,
+			   struct mhi_result *mhi_result)
+{
+	struct uci_dev *udev = dev_get_drvdata(&mhi_dev->dev);
+	struct uci_chan *uchan = udev->uchan;
+	struct device *dev = &mhi_dev->dev;
+
+	dev_dbg(dev, "%s: status: %d xfer_len: %zu\n", __func__,
+		mhi_result->transaction_status, mhi_result->bytes_xferd);
+
+	kfree(mhi_result->buf_addr);
+
+	if (!mhi_result->transaction_status)
+		wake_up(&uchan->ul_wq);
+}
+
+static void mhi_dl_xfer_cb(struct mhi_device *mhi_dev,
+			   struct mhi_result *mhi_result)
+{
+	struct uci_dev *udev = dev_get_drvdata(&mhi_dev->dev);
+	struct uci_chan *uchan = udev->uchan;
+	struct device *dev = &mhi_dev->dev;
+	struct uci_buf *ubuf;
+	size_t dl_buf_size = udev->mtu - sizeof(*ubuf);
+
+	dev_dbg(dev, "%s: status: %d receive_len: %zu\n", __func__,
+		mhi_result->transaction_status, mhi_result->bytes_xferd);
+
+	if (mhi_result->transaction_status &&
+	    mhi_result->transaction_status != -EOVERFLOW) {
+		kfree(mhi_result->buf_addr);
+		return;
+	}
+
+	ubuf = mhi_result->buf_addr + dl_buf_size;
+	ubuf->data = mhi_result->buf_addr;
+	ubuf->len = mhi_result->bytes_xferd;
+	spin_lock_bh(&uchan->dl_pending_lock);
+	list_add_tail(&ubuf->node, &uchan->dl_pending);
+	spin_unlock_bh(&uchan->dl_pending_lock);
+
+	wake_up(&uchan->dl_wq);
+}
+
+static int mhi_uci_probe(struct mhi_device *mhi_dev,
+			 const struct mhi_device_id *id)
+{
+	struct uci_dev *udev;
+	struct mhi_controller *mhi_cntrl = mhi_dev->mhi_cntrl;
+	struct device *dev;
+	int index;
+
+	udev = kzalloc(sizeof(*udev), GFP_KERNEL);
+	if (!udev)
+		return -ENOMEM;
+
+	kref_init(&udev->ref_count);
+	mutex_init(&udev->lock);
+	udev->mhi_dev = mhi_dev;
+
+	mutex_lock(&uci_drv_mutex);
+	index = idr_alloc(&uci_idr, udev, 0, MHI_MAX_UCI_MINORS, GFP_KERNEL);
+	mutex_unlock(&uci_drv_mutex);
+	if (index < 0) {
+		kfree(udev);
+		return index;
+	}
+
+	udev->minor = index;
+
+	udev->mtu = min_t(size_t, id->driver_data, MHI_MAX_MTU);
+	dev_set_drvdata(&mhi_dev->dev, udev);
+	udev->enabled = true;
+
+	/* create device file node /dev/mhi_<cntrl_dev_name>_<mhi_dev_name> */
+	dev = device_create(uci_dev_class, &mhi_dev->dev,
+			    MKDEV(uci_dev_major, index), udev,
+			    MHI_DEVICE_NAME "_%s_%s",
+			    dev_name(mhi_cntrl->cntrl_dev), mhi_dev->name);
+	if (IS_ERR(dev)) {
+		mutex_lock(&uci_drv_mutex);
+		idr_remove(&uci_idr, udev->minor);
+		mutex_unlock(&uci_drv_mutex);
+		dev_set_drvdata(&mhi_dev->dev, NULL);
+		kfree(udev);
+		return PTR_ERR(dev);
+	}
+
+	dev_dbg(&mhi_dev->dev, "probed uci dev: %s\n", id->chan);
+
+	return 0;
+};
+
+static void mhi_uci_remove(struct mhi_device *mhi_dev)
+{
+	struct uci_dev *udev = dev_get_drvdata(&mhi_dev->dev);
+
+	/* disable the node */
+	mutex_lock(&udev->lock);
+	udev->enabled = false;
+
+	/* delete the node to prevent new opens */
+	device_destroy(uci_dev_class, MKDEV(uci_dev_major, udev->minor));
+
+	/* return error for any blocked read or write */
+	if (udev->uchan) {
+		wake_up(&udev->uchan->ul_wq);
+		wake_up(&udev->uchan->dl_wq);
+	}
+	mutex_unlock(&udev->lock);
+
+	mutex_lock(&uci_drv_mutex);
+	idr_remove(&uci_idr, udev->minor);
+	kref_put(&udev->ref_count, mhi_uci_dev_release);
+	mutex_unlock(&uci_drv_mutex);
+}
+
+/* .driver_data stores max mtu */
+static const struct mhi_device_id mhi_uci_match_table[] = {
+	{ .chan = "LOOPBACK", .driver_data = 0x1000},
+	{},
+};
+MODULE_DEVICE_TABLE(mhi, mhi_uci_match_table);
+
+static struct mhi_driver mhi_uci_driver = {
+	.id_table = mhi_uci_match_table,
+	.remove = mhi_uci_remove,
+	.probe = mhi_uci_probe,
+	.ul_xfer_cb = mhi_ul_xfer_cb,
+	.dl_xfer_cb = mhi_dl_xfer_cb,
+	.driver = {
+		.name = MHI_UCI_DRIVER_NAME,
+	},
+};
+
+static int __init mhi_uci_init(void)
+{
+	int ret;
+
+	ret = register_chrdev(0, MHI_UCI_DRIVER_NAME, &mhidev_fops);
+	if (ret < 0)
+		return ret;
+
+	uci_dev_major = ret;
+	uci_dev_class = class_create(THIS_MODULE, MHI_UCI_DRIVER_NAME);
+	if (IS_ERR(uci_dev_class)) {
+		unregister_chrdev(uci_dev_major, MHI_UCI_DRIVER_NAME);
+		return PTR_ERR(uci_dev_class);
+	}
+
+	ret = mhi_driver_register(&mhi_uci_driver);
+	if (ret) {
+		class_destroy(uci_dev_class);
+		unregister_chrdev(uci_dev_major, MHI_UCI_DRIVER_NAME);
+	}
+
+	return ret;
+}
+
+static void __exit mhi_uci_exit(void)
+{
+	mhi_driver_unregister(&mhi_uci_driver);
+	class_destroy(uci_dev_class);
+	unregister_chrdev(uci_dev_major, MHI_UCI_DRIVER_NAME);
+	idr_destroy(&uci_idr);
+}
+
+module_init(mhi_uci_init);
+module_exit(mhi_uci_exit);
+MODULE_LICENSE("GPL v2");
+MODULE_DESCRIPTION("MHI UCI Driver");
-- 
The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum,
a Linux Foundation Collaborative Project

Re: [PATCH v12 4/5] bus: mhi: Add userspace client interface driver

[Loic Poulain]

Just one comment:

On Mon, 16 Nov 2020 at 23:46, Hemant Kumar <hemantk@codeaurora.org> wrote:
>
> This MHI client driver allows userspace clients to transfer
> raw data between MHI device and host using standard file operations.
> Driver instantiates UCI device object which is associated to device
> file node. UCI device object instantiates UCI channel object when device
> file node is opened. UCI channel object is used to manage MHI channels
> by calling MHI core APIs for read and write operations. MHI channels
> are started as part of device open(). MHI channels remain in start
> state until last release() is called on UCI device file node. Device
> file node is created with format
>
> /dev/mhi_<controller_name>_<mhi_device_name>
>
> Currently it supports LOOPBACK channel.
>
> Signed-off-by: Hemant Kumar <hemantk@codeaurora.org>
> ---
>  drivers/bus/mhi/Kconfig  |  13 +
>  drivers/bus/mhi/Makefile |   3 +
>  drivers/bus/mhi/uci.c    | 667 +++++++++++++++++++++++++++++++++++++++++++++++
>  3 files changed, 683 insertions(+)
>  create mode 100644 drivers/bus/mhi/uci.c
>
> diff --git a/drivers/bus/mhi/Kconfig b/drivers/bus/mhi/Kconfig
> index da5cd0c..5194e8e 100644
> --- a/drivers/bus/mhi/Kconfig
> +++ b/drivers/bus/mhi/Kconfig
> @@ -29,3 +29,16 @@ config MHI_BUS_PCI_GENERIC
>           This driver provides MHI PCI controller driver for devices such as
>           Qualcomm SDX55 based PCIe modems.
>
> +config MHI_UCI
> +       tristate "MHI UCI"
> +       depends on MHI_BUS
> +       help
> +         MHI based Userspace Client Interface (UCI) driver is used for
> +         transferring raw data between host and device using standard file
> +         operations from userspace. Open, read, write, poll and close
> +         operations are supported by this driver. Please check
> +         mhi_uci_match_table for all supported channels that are exposed to
> +         userspace.
> +
> +         To compile this driver as a module, choose M here: the module will be
> +         called mhi_uci.
> diff --git a/drivers/bus/mhi/Makefile b/drivers/bus/mhi/Makefile
> index 0a2d778..69f2111 100644
> --- a/drivers/bus/mhi/Makefile
> +++ b/drivers/bus/mhi/Makefile
> @@ -4,3 +4,6 @@ obj-y += core/
>  obj-$(CONFIG_MHI_BUS_PCI_GENERIC) += mhi_pci_generic.o
>  mhi_pci_generic-y += pci_generic.o
>
> +# MHI client
> +mhi_uci-y := uci.o
> +obj-$(CONFIG_MHI_UCI) += mhi_uci.o
> diff --git a/drivers/bus/mhi/uci.c b/drivers/bus/mhi/uci.c
> new file mode 100644
> index 0000000..75b0831
> --- /dev/null
> +++ b/drivers/bus/mhi/uci.c
> @@ -0,0 +1,667 @@
> +// SPDX-License-Identifier: GPL-2.0-only
> +/* Copyright (c) 2018-2020, The Linux Foundation. All rights reserved.*/
> +
> +#include <linux/kernel.h>
> +#include <linux/mhi.h>
> +#include <linux/mod_devicetable.h>
> +#include <linux/module.h>
> +#include <linux/poll.h>
> +
> +#define MHI_DEVICE_NAME "mhi"
> +#define MHI_UCI_DRIVER_NAME "mhi_uci"
> +#define MHI_MAX_UCI_MINORS 128
> +
> +static DEFINE_IDR(uci_idr);
> +static DEFINE_MUTEX(uci_drv_mutex);
> +static struct class *uci_dev_class;
> +static int uci_dev_major;
> +
> +/**
> + * struct uci_chan - MHI channel for a UCI device
> + * @udev: associated UCI device object
> + * @ul_wq: wait queue for writer
> + * @write_lock: mutex write lock for ul channel
> + * @dl_wq: wait queue for reader
> + * @read_lock: mutex read lock for dl channel
> + * @dl_pending_lock: spin lock for dl_pending list
> + * @dl_pending: list of dl buffers userspace is waiting to read
> + * @cur_buf: current buffer userspace is reading
> + * @dl_size: size of the current dl buffer userspace is reading
> + * @ref_count: uci_chan reference count
> + */
> +struct uci_chan {
> +       struct uci_dev *udev;
> +       wait_queue_head_t ul_wq;
> +
> +       /* ul channel lock to synchronize multiple writes */
> +       struct mutex write_lock;
> +
> +       wait_queue_head_t dl_wq;
> +
> +       /* dl channel lock to synchronize multiple reads */
> +       struct mutex read_lock;
> +
> +       /*
> +        * protects pending list in bh context, channel release, read and
> +        * poll
> +        */
> +       spinlock_t dl_pending_lock;
> +
> +       struct list_head dl_pending;
> +       struct uci_buf *cur_buf;
> +       size_t dl_size;
> +       struct kref ref_count;
> +};
> +
> +/**
> + * struct uci_buf - UCI buffer
> + * @data: data buffer
> + * @len: length of data buffer
> + * @node: list node of the UCI buffer
> + */
> +struct uci_buf {
> +       void *data;
> +       size_t len;
> +       struct list_head node;
> +};
> +
> +/**
> + * struct uci_dev - MHI UCI device
> + * @minor: UCI device node minor number
> + * @mhi_dev: associated mhi device object
> + * @uchan: UCI uplink and downlink channel object
> + * @mtu: max TRE buffer length
> + * @enabled: Flag to track the state of the UCI device
> + * @lock: mutex lock to manage uchan object
> + * @ref_count: uci_dev reference count
> + */
> +struct uci_dev {
> +       unsigned int minor;
> +       struct mhi_device *mhi_dev;
> +       struct uci_chan *uchan;
> +       size_t mtu;
> +       bool enabled;
> +
> +       /* synchronize open, release and driver remove */
> +       struct mutex lock;
> +       struct kref ref_count;
> +};
> +
> +static void mhi_uci_dev_chan_release(struct kref *ref)
> +{
> +       struct uci_buf *buf_itr, *tmp;
> +       struct uci_chan *uchan =
> +               container_of(ref, struct uci_chan, ref_count);
> +
> +       if (uchan->udev->enabled)
> +               mhi_unprepare_from_transfer(uchan->udev->mhi_dev);
> +
> +       spin_lock_bh(&uchan->dl_pending_lock);
> +       list_for_each_entry_safe(buf_itr, tmp, &uchan->dl_pending, node) {
> +               list_del(&buf_itr->node);
> +               kfree(buf_itr->data);
> +       }
> +       spin_unlock_bh(&uchan->dl_pending_lock);
> +
> +       wake_up(&uchan->ul_wq);
> +       wake_up(&uchan->dl_wq);
> +
> +       mutex_lock(&uchan->read_lock);
> +       if (uchan->cur_buf)
> +               kfree(uchan->cur_buf->data);
> +
> +       uchan->cur_buf = NULL;
> +       mutex_unlock(&uchan->read_lock);
> +
> +       mutex_destroy(&uchan->write_lock);
> +       mutex_destroy(&uchan->read_lock);
> +
> +       uchan->udev->uchan = NULL;
> +       kfree(uchan);
> +}
> +
> +static int mhi_queue_inbound(struct uci_dev *udev)
> +{
> +       struct mhi_device *mhi_dev = udev->mhi_dev;
> +       struct device *dev = &mhi_dev->dev;
> +       int nr_desc, i, ret = -EIO;
> +       size_t dl_buf_size;
> +       void *buf;
> +       struct uci_buf *ubuf;
> +
> +       /*
> +        * skip queuing without error if dl channel is not supported. This
> +        * allows open to succeed for udev, supporting ul only channel.
> +        */
> +       if (!udev->mhi_dev->dl_chan)
> +               return 0;
> +
> +       nr_desc = mhi_get_free_desc_count(mhi_dev, DMA_FROM_DEVICE);
> +
> +       for (i = 0; i < nr_desc; i++) {
> +               buf = kmalloc(udev->mtu, GFP_KERNEL);
> +               if (!buf)
> +                       return -ENOMEM;
> +
> +               dl_buf_size = udev->mtu - sizeof(*ubuf);
> +
> +               /* save uci_buf info at the end of buf */
> +               ubuf = buf + dl_buf_size;
> +               ubuf->data = buf;
> +
> +               dev_dbg(dev, "Allocated buf %d of %d size %zu\n", i, nr_desc,
> +                       dl_buf_size);
> +
> +               ret = mhi_queue_buf(mhi_dev, DMA_FROM_DEVICE, buf, dl_buf_size,
> +                                   MHI_EOT);
> +               if (ret) {
> +                       kfree(buf);
> +                       dev_err(dev, "Failed to queue buffer %d\n", i);
> +                       return ret;
> +               }
> +       }
> +
> +       return ret;
> +}
> +
> +static int mhi_uci_dev_start_chan(struct uci_dev *udev)
> +{
> +       int ret = 0;
> +       struct uci_chan *uchan;
> +
> +       mutex_lock(&udev->lock);
> +       if (!udev->uchan || !kref_get_unless_zero(&udev->uchan->ref_count)) {
> +               uchan = kzalloc(sizeof(*uchan), GFP_KERNEL);
> +               if (!uchan) {
> +                       ret = -ENOMEM;
> +                       goto error_chan_start;
> +               }
> +
> +               udev->uchan = uchan;
> +               uchan->udev = udev;
> +               init_waitqueue_head(&uchan->ul_wq);
> +               init_waitqueue_head(&uchan->dl_wq);
> +               mutex_init(&uchan->write_lock);
> +               mutex_init(&uchan->read_lock);
> +               spin_lock_init(&uchan->dl_pending_lock);
> +               INIT_LIST_HEAD(&uchan->dl_pending);
> +
> +               ret = mhi_prepare_for_transfer(udev->mhi_dev);
> +               if (ret) {
> +                       dev_err(&udev->mhi_dev->dev, "Error starting transfer channels\n");
> +                       goto error_chan_cleanup;
> +               }
> +
> +               ret = mhi_queue_inbound(udev);
> +               if (ret)
> +                       goto error_chan_cleanup;
> +
> +               kref_init(&uchan->ref_count);
> +       }
> +
> +       mutex_unlock(&udev->lock);
> +
> +       return 0;
> +
> +error_chan_cleanup:
> +       mhi_uci_dev_chan_release(&uchan->ref_count);
> +error_chan_start:
> +       mutex_unlock(&udev->lock);
> +       return ret;
> +}
> +
> +static void mhi_uci_dev_release(struct kref *ref)
> +{
> +       struct uci_dev *udev =
> +               container_of(ref, struct uci_dev, ref_count);
> +
> +       mutex_destroy(&udev->lock);
> +
> +       kfree(udev);
> +}
> +
> +static int mhi_uci_open(struct inode *inode, struct file *filp)
> +{
> +       unsigned int minor = iminor(inode);
> +       struct uci_dev *udev = NULL;
> +       int ret;
> +
> +       mutex_lock(&uci_drv_mutex);
> +       udev = idr_find(&uci_idr, minor);
> +       if (!udev) {
> +               pr_debug("uci dev: minor %d not found\n", minor);
> +               mutex_unlock(&uci_drv_mutex);
> +               return -ENODEV;
> +       }
> +
> +       kref_get(&udev->ref_count);
> +       mutex_unlock(&uci_drv_mutex);
> +
> +       ret = mhi_uci_dev_start_chan(udev);
> +       if (ret) {
> +               kref_put(&udev->ref_count, mhi_uci_dev_release);
> +               return ret;
> +       }
> +
> +       filp->private_data = udev;
> +
> +       return 0;
> +}
> +
> +static int mhi_uci_release(struct inode *inode, struct file *file)
> +{
> +       struct uci_dev *udev = file->private_data;
> +
> +       mutex_lock(&udev->lock);
> +       kref_put(&udev->uchan->ref_count, mhi_uci_dev_chan_release);
> +       mutex_unlock(&udev->lock);
> +
> +       kref_put(&udev->ref_count, mhi_uci_dev_release);
> +
> +       return 0;
> +}
> +
> +static __poll_t mhi_uci_poll(struct file *file, poll_table *wait)
> +{
> +       struct uci_dev *udev = file->private_data;
> +       struct mhi_device *mhi_dev = udev->mhi_dev;
> +       struct device *dev = &mhi_dev->dev;
> +       struct uci_chan *uchan = udev->uchan;
> +       __poll_t mask = 0;
> +
> +       poll_wait(file, &udev->uchan->ul_wq, wait);
> +       poll_wait(file, &udev->uchan->dl_wq, wait);
> +
> +       if (!udev->enabled) {
> +               mask = EPOLLERR;
> +               goto done;
> +       }
> +
> +       spin_lock_bh(&uchan->dl_pending_lock);
> +       if (!list_empty(&uchan->dl_pending) || uchan->cur_buf)
> +               mask |= EPOLLIN | EPOLLRDNORM;
> +       spin_unlock_bh(&uchan->dl_pending_lock);
> +
> +       if (mhi_get_free_desc_count(mhi_dev, DMA_TO_DEVICE) > 0)
> +               mask |= EPOLLOUT | EPOLLWRNORM;
> +
> +       dev_dbg(dev, "Client attempted to poll, returning mask 0x%x\n", mask);
> +
> +done:
> +       return mask;
> +}
> +
> +static ssize_t mhi_uci_write(struct file *file,
> +                            const char __user *buf,
> +                            size_t count,
> +                            loff_t *offp)
> +{
> +       struct uci_dev *udev = file->private_data;
> +       struct mhi_device *mhi_dev = udev->mhi_dev;
> +       struct device *dev = &mhi_dev->dev;
> +       struct uci_chan *uchan = udev->uchan;
> +       size_t bytes_xfered = 0;
> +       int ret, nr_desc = 0;
> +
> +       /* if ul channel is not supported return error */
> +       if (!mhi_dev->ul_chan)
> +               return -EOPNOTSUPP;
> +
> +       if (!buf || !count)
> +               return -EINVAL;
> +
> +       dev_dbg(dev, "%s: to xfer: %zu bytes\n", __func__, count);
> +
> +       if (mutex_lock_interruptible(&uchan->write_lock))
> +               return -EINTR;
> +
> +       while (count) {
> +               size_t xfer_size;
> +               void *kbuf;
> +               enum mhi_flags flags;
> +
> +               /* wait for free descriptors */
> +               ret = wait_event_interruptible(uchan->ul_wq,
> +                                              (!udev->enabled) ||
> +                               (nr_desc = mhi_get_free_desc_count(mhi_dev,
> +                                              DMA_TO_DEVICE)) > 0);
> +
> +               if (ret == -ERESTARTSYS) {
> +                       dev_dbg(dev, "Interrupted by a signal in %s, exiting\n",
> +                               __func__);
> +                       goto err_mtx_unlock;
> +               }
> +
> +               if (!udev->enabled) {
> +                       ret = -ENODEV;
> +                       goto err_mtx_unlock;
> +               }
> +
> +               xfer_size = min_t(size_t, count, udev->mtu);
> +               kbuf = kmalloc(xfer_size, GFP_KERNEL);
> +               if (!kbuf) {
> +                       ret = -ENOMEM;
> +                       goto err_mtx_unlock;
> +               }
> +
> +               ret = copy_from_user(kbuf, buf, xfer_size);
> +               if (ret) {
> +                       kfree(kbuf);
> +                       ret = -EFAULT;
> +                       goto err_mtx_unlock;
> +               }
> +
> +               /* if ring is full after this force EOT */
> +               if (nr_desc > 1 && (count - xfer_size))
> +                       flags = MHI_CHAIN;
> +               else
> +                       flags = MHI_EOT;
> +
> +               ret = mhi_queue_buf(mhi_dev, DMA_TO_DEVICE, kbuf, xfer_size,
> +                                   flags);
> +               if (ret) {
> +                       kfree(kbuf);
> +                       goto err_mtx_unlock;
> +               }
> +
> +               bytes_xfered += xfer_size;
> +               count -= xfer_size;
> +               buf += xfer_size;
> +       }
> +
> +       mutex_unlock(&uchan->write_lock);
> +       dev_dbg(dev, "%s: bytes xferred: %zu\n", __func__, bytes_xfered);
> +
> +       return bytes_xfered;
> +
> +err_mtx_unlock:
> +       mutex_unlock(&uchan->write_lock);
> +
> +       return ret;
> +}
> +
> +static ssize_t mhi_uci_read(struct file *file,
> +                           char __user *buf,
> +                           size_t count,
> +                           loff_t *ppos)
> +{
> +       struct uci_dev *udev = file->private_data;
> +       struct mhi_device *mhi_dev = udev->mhi_dev;
> +       struct uci_chan *uchan = udev->uchan;
> +       struct device *dev = &mhi_dev->dev;
> +       struct uci_buf *ubuf;
> +       size_t rx_buf_size;
> +       char *ptr;
> +       size_t to_copy;
> +       int ret = 0;
> +
> +       /* if dl channel is not supported return error */
> +       if (!mhi_dev->dl_chan)
> +               return -EOPNOTSUPP;
> +
> +       if (!buf)
> +               return -EINVAL;
> +
> +       if (mutex_lock_interruptible(&uchan->read_lock))
> +               return -EINTR;
> +
> +       spin_lock_bh(&uchan->dl_pending_lock);
> +       /* No data available to read, wait */
> +       if (!uchan->cur_buf && list_empty(&uchan->dl_pending)) {
> +               dev_dbg(dev, "No data available to read, waiting\n");
> +
> +               spin_unlock_bh(&uchan->dl_pending_lock);
> +               ret = wait_event_interruptible(uchan->dl_wq,
> +                                              (!udev->enabled ||
> +                                             !list_empty(&uchan->dl_pending)));
> +
> +               if (ret == -ERESTARTSYS) {
> +                       dev_dbg(dev, "Interrupted by a signal in %s, exiting\n",
> +                               __func__);
> +                       goto err_mtx_unlock;
> +               }
> +
> +               if (!udev->enabled) {
> +                       ret = -ENODEV;
> +                       goto err_mtx_unlock;
> +               }
> +               spin_lock_bh(&uchan->dl_pending_lock);
> +       }
> +
> +       /* new read, get the next descriptor from the list */
> +       if (!uchan->cur_buf) {
> +               ubuf = list_first_entry_or_null(&uchan->dl_pending,
> +                                               struct uci_buf, node);
> +               if (!ubuf) {
> +                       ret = -EIO;
> +                       goto err_spin_unlock;
> +               }
> +
> +               list_del(&ubuf->node);
> +               uchan->cur_buf = ubuf;
> +               uchan->dl_size = ubuf->len;
> +               dev_dbg(dev, "Got pkt of size: %zu\n", uchan->dl_size);
> +       }
> +       spin_unlock_bh(&uchan->dl_pending_lock);
> +
> +       ubuf = uchan->cur_buf;
> +
> +       /* Copy the buffer to user space */
> +       to_copy = min_t(size_t, count, uchan->dl_size);
> +       ptr = ubuf->data + (ubuf->len - uchan->dl_size);
> +
> +       ret = copy_to_user(buf, ptr, to_copy);
> +       if (ret) {
> +               ret = -EFAULT;
> +               goto err_mtx_unlock;
> +       }
> +
> +       dev_dbg(dev, "Copied %zu of %zu bytes\n", to_copy, uchan->dl_size);
> +       uchan->dl_size -= to_copy;
> +
> +       /* we finished with this buffer, queue it back to hardware */
> +       if (!uchan->dl_size) {
> +               uchan->cur_buf = NULL;
> +
> +               rx_buf_size = udev->mtu - sizeof(*ubuf);
> +               ret = mhi_queue_buf(mhi_dev, DMA_FROM_DEVICE, ubuf->data,
> +                                   rx_buf_size, MHI_EOT);
> +               if (ret) {
> +                       dev_err(dev, "Failed to recycle element: %d\n", ret);
> +                       kfree(ubuf->data);
> +                       goto err_mtx_unlock;
> +               }
> +       }
> +       mutex_unlock(&uchan->read_lock);
> +
> +       dev_dbg(dev, "%s: Returning %zu bytes\n", __func__, to_copy);
> +
> +       return to_copy;
> +
> +err_spin_unlock:
> +       spin_unlock_bh(&uchan->dl_pending_lock);
> +err_mtx_unlock:
> +       mutex_unlock(&uchan->read_lock);
> +       return ret;
> +}
> +
> +static const struct file_operations mhidev_fops = {
> +       .owner = THIS_MODULE,
> +       .open = mhi_uci_open,
> +       .release = mhi_uci_release,
> +       .read = mhi_uci_read,
> +       .write = mhi_uci_write,
> +       .poll = mhi_uci_poll,
> +};
> +
> +static void mhi_ul_xfer_cb(struct mhi_device *mhi_dev,
> +                          struct mhi_result *mhi_result)
> +{
> +       struct uci_dev *udev = dev_get_drvdata(&mhi_dev->dev);
> +       struct uci_chan *uchan = udev->uchan;
> +       struct device *dev = &mhi_dev->dev;
> +
> +       dev_dbg(dev, "%s: status: %d xfer_len: %zu\n", __func__,
> +               mhi_result->transaction_status, mhi_result->bytes_xferd);
> +
> +       kfree(mhi_result->buf_addr);
> +
> +       if (!mhi_result->transaction_status)
> +               wake_up(&uchan->ul_wq);
> +}
> +
> +static void mhi_dl_xfer_cb(struct mhi_device *mhi_dev,
> +                          struct mhi_result *mhi_result)
> +{
> +       struct uci_dev *udev = dev_get_drvdata(&mhi_dev->dev);
> +       struct uci_chan *uchan = udev->uchan;
> +       struct device *dev = &mhi_dev->dev;
> +       struct uci_buf *ubuf;
> +       size_t dl_buf_size = udev->mtu - sizeof(*ubuf);
> +
> +       dev_dbg(dev, "%s: status: %d receive_len: %zu\n", __func__,
> +               mhi_result->transaction_status, mhi_result->bytes_xferd);
> +
> +       if (mhi_result->transaction_status &&
> +           mhi_result->transaction_status != -EOVERFLOW) {
> +               kfree(mhi_result->buf_addr);
> +               return;
> +       }
> +
> +       ubuf = mhi_result->buf_addr + dl_buf_size;
> +       ubuf->data = mhi_result->buf_addr;
> +       ubuf->len = mhi_result->bytes_xferd;
> +       spin_lock_bh(&uchan->dl_pending_lock);
> +       list_add_tail(&ubuf->node, &uchan->dl_pending);
> +       spin_unlock_bh(&uchan->dl_pending_lock);
> +
> +       wake_up(&uchan->dl_wq);
> +}
> +
> +static int mhi_uci_probe(struct mhi_device *mhi_dev,
> +                        const struct mhi_device_id *id)
> +{
> +       struct uci_dev *udev;
> +       struct mhi_controller *mhi_cntrl = mhi_dev->mhi_cntrl;
> +       struct device *dev;
> +       int index;
> +
> +       udev = kzalloc(sizeof(*udev), GFP_KERNEL);
> +       if (!udev)
> +               return -ENOMEM;
> +
> +       kref_init(&udev->ref_count);
> +       mutex_init(&udev->lock);
> +       udev->mhi_dev = mhi_dev;
> +
> +       mutex_lock(&uci_drv_mutex);
> +       index = idr_alloc(&uci_idr, udev, 0, MHI_MAX_UCI_MINORS, GFP_KERNEL);
> +       mutex_unlock(&uci_drv_mutex);
> +       if (index < 0) {
> +               kfree(udev);
> +               return index;
> +       }
> +
> +       udev->minor = index;
> +
> +       udev->mtu = min_t(size_t, id->driver_data, MHI_MAX_MTU);
> +       dev_set_drvdata(&mhi_dev->dev, udev);
> +       udev->enabled = true;
> +
> +       /* create device file node /dev/mhi_<cntrl_dev_name>_<mhi_dev_name> */
> +       dev = device_create(uci_dev_class, &mhi_dev->dev,
> +                           MKDEV(uci_dev_major, index), udev,
> +                           MHI_DEVICE_NAME "_%s_%s",
> +                           dev_name(mhi_cntrl->cntrl_dev), mhi_dev->name);

Here you can simply do:
MHI_DEVICE_NAME "_%s", dev_name(&mhi_dev->dev));

That will do exactly the same, and you can get rid of the mhi_cntrl reference.

[PATCH v12 5/5] selftest: mhi: Add support to test MHI LOOPBACK channel

[Hemant Kumar]

Loopback test opens the MHI device file node and writes
a data buffer to it. MHI UCI kernel space driver copies
the data and sends it to MHI uplink (Tx) LOOPBACK channel.
MHI device loops back the same data to MHI downlink (Rx)
LOOPBACK channel. This data is read by test application
and compared against the data sent. Test passes if data
buffer matches between Tx and Rx. Test application performs
open(), poll(), write(), read() and close() file operations.

Signed-off-by: Hemant Kumar <hemantk@codeaurora.org>
---
 Documentation/mhi/uci.rst                          |  32 +
 tools/testing/selftests/Makefile                   |   1 +
 tools/testing/selftests/drivers/.gitignore         |   1 +
 tools/testing/selftests/drivers/mhi/Makefile       |   8 +
 tools/testing/selftests/drivers/mhi/config         |   2 +
 .../testing/selftests/drivers/mhi/loopback_test.c  | 802 +++++++++++++++++++++
 6 files changed, 846 insertions(+)
 create mode 100644 tools/testing/selftests/drivers/mhi/Makefile
 create mode 100644 tools/testing/selftests/drivers/mhi/config
 create mode 100644 tools/testing/selftests/drivers/mhi/loopback_test.c

diff --git a/Documentation/mhi/uci.rst b/Documentation/mhi/uci.rst
index ce8740e..0a04afe 100644
--- a/Documentation/mhi/uci.rst
+++ b/Documentation/mhi/uci.rst
@@ -79,6 +79,38 @@ MHI client driver performs read operation, same data gets looped back to MHI
 host using LOOPBACK channel 1. LOOPBACK channel is used to verify data path
 and data integrity between MHI Host and MHI device.
 
+Loopback Test
+~~~~~~~~~~~~~
+
+Loopback test application is used to verify data integrity between MHI host and
+MHI device over LOOPBACK channel. This also confirms that basic MHI data path
+is working properly. Test performs write() to send tx buffer to MHI device file
+node for LOOPBACK uplink channel. MHI LOOPBACK downlink channel loops back
+transmit data to MHI Host. Test application receives data in receive buffer as
+part of read(). It verifies if tx buffer matches rx buffer. Test application
+performs poll() before making write() and read() system calls. Test passes if
+match is found.
+
+Test is present under tools/testing/selftests/drivers/mhi. It is compiled using
+following command in same dir:-
+
+make loopback_test
+
+Test is run using following command arguments:-
+
+loopback_test -c <device_node> -b <transmit buffer size> -l <log level> -i
+<number of iterations>
+
+Required argument:
+-c : loopback chardev node
+
+Optional argument:
+-b : transmit buffer size. If not present 1024 bytes size transmit buffer
+     is sent.
+-i : Number of iterations to perform, If not present only one transmit buffer
+     is sent.
+-l : Log level. If not present defaults to DBG_LVL_INFO.
+
 Other Use Cases
 ---------------
 
diff --git a/tools/testing/selftests/Makefile b/tools/testing/selftests/Makefile
index d9c2835..084bc1e 100644
--- a/tools/testing/selftests/Makefile
+++ b/tools/testing/selftests/Makefile
@@ -10,6 +10,7 @@ TARGETS += core
 TARGETS += cpufreq
 TARGETS += cpu-hotplug
 TARGETS += drivers/dma-buf
+TARGETS += drivers/mhi
 TARGETS += efivarfs
 TARGETS += exec
 TARGETS += filesystems
diff --git a/tools/testing/selftests/drivers/.gitignore b/tools/testing/selftests/drivers/.gitignore
index ca74f2e..e4806d5 100644
--- a/tools/testing/selftests/drivers/.gitignore
+++ b/tools/testing/selftests/drivers/.gitignore
@@ -1,2 +1,3 @@
 # SPDX-License-Identifier: GPL-2.0-only
 /dma-buf/udmabuf
+/mhi/loopback_test
diff --git a/tools/testing/selftests/drivers/mhi/Makefile b/tools/testing/selftests/drivers/mhi/Makefile
new file mode 100644
index 0000000..c06c925
--- /dev/null
+++ b/tools/testing/selftests/drivers/mhi/Makefile
@@ -0,0 +1,8 @@
+# SPDX-License-Identifier: GPL-2.0-only
+CFLAGS += -I../../../../../usr/include/ -g -Wall
+
+LDLIBS = -lpthread
+TEST_GEN_PROGS := loopback_test
+
+include ../../lib.mk
+
diff --git a/tools/testing/selftests/drivers/mhi/config b/tools/testing/selftests/drivers/mhi/config
new file mode 100644
index 0000000..471dc92
--- /dev/null
+++ b/tools/testing/selftests/drivers/mhi/config
@@ -0,0 +1,2 @@
+CONFIG_MHI_BUS=y
+CONFIG_MHi_UCI=y
diff --git a/tools/testing/selftests/drivers/mhi/loopback_test.c b/tools/testing/selftests/drivers/mhi/loopback_test.c
new file mode 100644
index 0000000..99b7712
--- /dev/null
+++ b/tools/testing/selftests/drivers/mhi/loopback_test.c
@@ -0,0 +1,802 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Loopback test application performs write() to send tx buffer to MHI device
+ * file node for LOOPBACK uplink channel. MHI LOOPBACK downlink channel loops
+ * back transmit data to MHI Host. Test application receives data in receive
+ * buffer as part of read(). It verifies if tx buffer matches rx buffer. Test
+ * application performs poll() before making write() and read() system
+ * calls. Test passes if match is found.
+ *
+ * Test is compiled using following command:-
+ *
+ * make loopback_test
+ *
+ * Test is run using following command arguments:-
+ *
+ * loopback_test -c <device_node> -b <transmit buffer size> -l <log level> -i
+ * <number of iterations>
+ *
+ * Required argument:
+ * -c : loopback chardev node
+ *
+ * Optional argument:
+ * -b : transmit buffer size. If not present 1024 bytes size transmit buffer
+ *      is sent.
+ * -i : Number of iterations to perform, If not present only one transmit buffer
+ *      is sent.
+ * -l : Log level. If not present defaults to DBG_LVL_INFO.
+ */
+
+#include <errno.h>
+#include <fcntl.h>
+#include <getopt.h>
+#include <pthread.h>
+#include <stdbool.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sys/poll.h>
+#include <unistd.h>
+
+enum debug_level {
+	DBG_LVL_VERBOSE,
+	DBG_LVL_INFO,
+	DBG_LVL_ERROR,
+};
+
+enum test_status {
+	TEST_STATUS_SUCCESS,
+	TEST_STATUS_ERROR,
+	TEST_STATUS_NO_DEV,
+};
+
+struct lb_test_ctx {
+	char dev_node[256];
+	unsigned char *tx_buff;
+	unsigned char *rx_buff;
+	unsigned int rx_pkt_count;
+	unsigned int tx_pkt_count;
+	int iterations;
+	bool iter_complete;
+	bool comp_complete;
+	bool test_complete;
+	bool all_complete;
+	unsigned long buff_size;
+	long byte_recvd;
+	long byte_sent;
+};
+
+bool force_exit;
+char write_data = 'a';
+int completed_iterations;
+
+struct lb_test_ctx test_ctxt;
+enum debug_level msg_lvl;
+struct pollfd read_fd;
+struct pollfd write_fd;
+enum test_status mhi_test_return_value;
+enum test_status tx_status;
+enum test_status rx_status;
+enum test_status cmp_rxtx_status;
+
+#define test_log(test_msg_lvl, format, ...) do { \
+		if (test_msg_lvl >= msg_lvl) \
+			fprintf(stderr, format, ##__VA_ARGS__); \
+} while (0)
+
+static void loopback_test_sleep_ms(int ms)
+{
+	usleep(1000 * ms);
+}
+
+static enum test_status loopback_test_open(struct pollfd *write_fd,
+					struct pollfd *read_fd, char *dev_name)
+{
+	enum test_status ret_val = TEST_STATUS_SUCCESS;
+
+	write_fd->fd = open(dev_name, O_SYNC | O_WRONLY);
+	if (write_fd->fd < 0) {
+		test_log(DBG_LVL_ERROR, "Error opening file for w: errno: %d\n", errno);
+		ret_val = TEST_STATUS_ERROR;
+	} else {
+		test_log(DBG_LVL_INFO, "Opened %s, return code: %i.\n",
+			 dev_name, write_fd->fd);
+		write_fd->events = POLLOUT;
+	}
+
+	read_fd->fd = open(dev_name, O_SYNC | O_RDONLY);
+	if (read_fd->fd < 0) {
+		test_log(DBG_LVL_ERROR, "Error opening file for r: errno: %d\n", errno);
+		ret_val = TEST_STATUS_ERROR;
+	} else {
+		test_log(DBG_LVL_INFO, "Opened %s, return code: %i.\n",
+			 dev_name, read_fd->fd);
+		read_fd->events = POLLIN;
+	}
+
+	return ret_val;
+}
+
+static enum test_status loopback_test_close(struct pollfd *write_fd,
+						 struct pollfd *read_fd)
+{
+	enum test_status ret_val = TEST_STATUS_SUCCESS;
+
+	if (close(read_fd->fd) == 0) {
+		test_log(DBG_LVL_INFO, "Closed device handle\n");
+	} else {
+		test_log(DBG_LVL_ERROR, "Unable to close handle to device\n");
+		ret_val = TEST_STATUS_ERROR;
+	}
+
+	if (close(write_fd->fd) == 0) {
+		test_log(DBG_LVL_INFO, "Closed device handle\n");
+	} else {
+		test_log(DBG_LVL_ERROR, "Unable to close handle to device\n");
+		ret_val = TEST_STATUS_ERROR;
+	}
+
+	return ret_val;
+}
+
+static enum test_status loopback_test_alloc_rx_tx_buff(void)
+{
+	test_ctxt.rx_buff = (unsigned char *)malloc(test_ctxt.buff_size);
+	if (!test_ctxt.rx_buff) {
+		test_log(DBG_LVL_ERROR, "Failed to allocate rx buff\n");
+		return TEST_STATUS_ERROR;
+	}
+
+	memset(test_ctxt.rx_buff, 0x00, sizeof(test_ctxt.buff_size));
+	test_ctxt.tx_buff = (unsigned char *)malloc(test_ctxt.buff_size);
+	if (!test_ctxt.tx_buff) {
+		test_log(DBG_LVL_ERROR, "Failed to allocate tx buff\n");
+		return TEST_STATUS_ERROR;
+	}
+
+	return TEST_STATUS_SUCCESS;
+}
+
+static enum test_status loopback_test_write(struct pollfd *write_fd)
+{
+	enum test_status ret_value = TEST_STATUS_SUCCESS;
+	signed long temp_bytes_sent = 0;
+	signed long total_bytes_sent = 0;
+
+	test_log(DBG_LVL_VERBOSE, "About to write %lu\n", test_ctxt.buff_size);
+
+	temp_bytes_sent = write(write_fd->fd,
+		test_ctxt.tx_buff + test_ctxt.byte_sent, test_ctxt.buff_size);
+
+	test_log(DBG_LVL_VERBOSE, "Returned %li\n", temp_bytes_sent);
+	test_log(DBG_LVL_INFO, "Wrote packet with %li bytes of %02x\n",
+		 temp_bytes_sent, *(test_ctxt.tx_buff + test_ctxt.byte_sent));
+
+	if (temp_bytes_sent < 0) {
+		/* write returned a negative value i.e. write failed */
+		test_log(DBG_LVL_ERROR, "write() failed: err code %d\n", errno);
+		return TEST_STATUS_ERROR;
+	}
+
+	if ((unsigned long)temp_bytes_sent > test_ctxt.buff_size) {
+		test_log(DBG_LVL_ERROR, "Wrote more bytes than intended\n");
+		return TEST_STATUS_ERROR;
+	}
+
+	if (temp_bytes_sent == 0) {
+		loopback_test_sleep_ms(10);
+	} else if (temp_bytes_sent > 0) {
+		test_ctxt.tx_pkt_count++;
+		test_ctxt.byte_sent += temp_bytes_sent;
+		total_bytes_sent += temp_bytes_sent;
+		test_log(DBG_LVL_INFO, "Total written packets %d\n",
+			 test_ctxt.tx_pkt_count);
+	}
+
+	return ret_value;
+}
+
+static void loopback_test_reset_ctxt(void)
+{
+	test_ctxt.byte_sent = 0;
+	__sync_synchronize();
+	test_ctxt.byte_recvd = 0;
+	test_ctxt.rx_pkt_count = 0;
+	test_ctxt.tx_pkt_count = 0;
+	test_ctxt.comp_complete = false;
+	memset((void *)test_ctxt.rx_buff, 0x00, test_ctxt.buff_size);
+}
+
+static enum test_status loopback_test_time_out(int *time_count)
+{
+	enum test_status ret_val = TEST_STATUS_SUCCESS;
+
+	loopback_test_sleep_ms(3);
+	if ((++*time_count) > 100000) {
+		test_log(DBG_LVL_ERROR, "Error: all bytes not received for this iteration\n");
+		ret_val = TEST_STATUS_ERROR;
+		while (1)
+			loopback_test_sleep_ms(1000);
+	}
+
+	return ret_val;
+}
+
+static enum test_status loopback_test_poll(struct pollfd *fd,
+						bool poll_timeout)
+{
+	enum test_status ret_val = TEST_STATUS_SUCCESS;
+	int poll_return = 0;
+	int i = 0;
+	int timeout = 1000; /* poll-wait 1 second */
+	int file_desc_type = -1;
+
+	if (fd->events == POLLIN) {
+		file_desc_type = 1; /* read */
+		test_log(DBG_LVL_VERBOSE,
+			 "Poll: opened read handle to device\n");
+	} else if (fd->events == POLLOUT) {
+		file_desc_type = 0; /* write */
+		test_log(DBG_LVL_VERBOSE,
+			 "Poll: opened write handle to device\n");
+	}
+
+	if (poll_timeout == false)
+		timeout = -1; /* poll-wait forever */
+
+	while (ret_val == TEST_STATUS_SUCCESS) {
+		if (force_exit == true) {
+			ret_val = TEST_STATUS_ERROR;
+		} else {
+			test_log(DBG_LVL_VERBOSE, "%s Polling %i\n",
+				 file_desc_type ? "Read" : "Write", i);
+
+			poll_return = poll(fd, 1, timeout);
+			if (poll_return == -1) {
+				test_log(DBG_LVL_ERROR, "%s Poll error - %d\n",
+					 file_desc_type ? "Read" : "Write",
+					 errno);
+				return TEST_STATUS_ERROR;
+			} else if (((file_desc_type == 1) &&
+				   (fd->revents & POLLIN)) ||
+				   ((file_desc_type == 0) &&
+				   (fd->revents & POLLOUT))) {
+				test_log(DBG_LVL_VERBOSE,
+					 "%s Poll Returned\n",
+					 file_desc_type ? "Read" : "Write");
+				return TEST_STATUS_SUCCESS;
+			} else if (poll_timeout == true) {
+				i++;
+				poll_return = 0;
+				if (i >= 250) {
+					test_log(DBG_LVL_ERROR,
+						 "Poll: %s Timed out: 10s\n",
+					file_desc_type ? "Read" : "Write");
+					return TEST_STATUS_ERROR;
+				}
+			}
+
+			loopback_test_sleep_ms(10);
+		}
+	}
+
+	return ret_val;
+}
+
+static void *loopback_test_rx(void *data)
+{
+	bool poll_timeout = true;
+	unsigned long read_size = test_ctxt.buff_size;
+	long temp_bytes_rec;
+	enum test_status status;
+
+	rx_status = TEST_STATUS_SUCCESS;
+
+	while (force_exit == false) {
+		if (test_ctxt.test_complete) {
+			test_log(DBG_LVL_INFO, "Rx: exiting thread\n");
+			pthread_exit(&rx_status);
+			return NULL;
+		}
+
+		while ((test_ctxt.byte_sent > test_ctxt.byte_recvd) &&
+		       (force_exit == false)) {
+			test_log(DBG_LVL_VERBOSE,
+				 "Rx: Bytes Sent: %li, Received %li\n",
+				test_ctxt.byte_sent, test_ctxt.byte_recvd);
+
+			temp_bytes_rec = 0;
+
+			if (test_ctxt.comp_complete == false) {
+				status = loopback_test_poll(&read_fd,
+							    poll_timeout);
+				if (status == TEST_STATUS_ERROR) {
+					if (test_ctxt.test_complete == true)
+						rx_status = TEST_STATUS_SUCCESS;
+					else
+						rx_status = TEST_STATUS_ERROR;
+
+					test_log(DBG_LVL_INFO,
+						 "Rx: exiting thread\n");
+					pthread_exit(&rx_status);
+					return NULL;
+				}
+
+				test_log(DBG_LVL_VERBOSE, "Rx: before read\n");
+				temp_bytes_rec = read(read_fd.fd,
+					test_ctxt.rx_buff + test_ctxt.byte_recvd,
+					read_size);
+				if (temp_bytes_rec < 0) {
+					test_log(DBG_LVL_ERROR,
+					"Rx: read() failed - err code %d\n",
+					errno);
+					rx_status = TEST_STATUS_ERROR;
+					pthread_exit(&rx_status);
+					return NULL;
+				}
+
+				if (temp_bytes_rec == 0) {
+					loopback_test_sleep_ms(10);
+					rx_status = TEST_STATUS_ERROR;
+					pthread_exit(&rx_status);
+					return NULL;
+				}
+
+				test_ctxt.rx_pkt_count++;
+				test_log(DBG_LVL_INFO,
+				"Rx: Read packet with %li bytes of %02x\n",
+				temp_bytes_rec,
+				*(test_ctxt.rx_buff + test_ctxt.byte_recvd));
+				test_ctxt.byte_recvd += temp_bytes_rec;
+				test_log(DBG_LVL_INFO,
+					 "Rx: Total byte_recvd: %li\n",
+					test_ctxt.byte_recvd);
+				test_log(DBG_LVL_INFO,
+					 "Rx: Total read packets %d\n",
+					test_ctxt.rx_pkt_count);
+				test_log(DBG_LVL_INFO,
+					 "Rx: %lu byte buff_size\n",
+					test_ctxt.buff_size);
+
+				read_fd.revents = 0;
+			}
+		}
+	}
+	rx_status = TEST_STATUS_ERROR;
+	pthread_exit(&rx_status);
+	return NULL;
+}
+
+/* This single compare thread, will compare each byte of tx and rx Buff */
+static void *loopback_test_compare_rxtx(void *data)
+{
+	int k;
+	bool completion = true;
+	long curr_ptr = 0;
+
+	test_log(DBG_LVL_INFO, "CompareRxTxThread: Inside thread\n");
+	cmp_rxtx_status = TEST_STATUS_SUCCESS;
+
+	for (;;) {
+		/* if the test is completed exit thread */
+		if (test_ctxt.all_complete == true) {
+			curr_ptr = 0;
+			test_log(DBG_LVL_INFO,
+				 "CompareRxTx: exiting thread\n");
+			pthread_exit(&cmp_rxtx_status);
+			return NULL;
+		}
+
+		/* Simply compares each byte in each Tx and Rx buffer */
+		while (curr_ptr < test_ctxt.byte_recvd) {
+			if (*(test_ctxt.rx_buff + curr_ptr) !=
+					*(test_ctxt.tx_buff + curr_ptr)) {
+				test_log(DBG_LVL_ERROR,
+					 "Mismatch Byte num %li\n", curr_ptr);
+				test_log(DBG_LVL_ERROR,
+					 "Bytes: Sent 0x%x, Received 0x%x\n",
+					 *(test_ctxt.tx_buff + curr_ptr),
+					 *(test_ctxt.rx_buff + curr_ptr));
+				test_log(DBG_LVL_VERBOSE, "Rx buffer dump:\n");
+				for (k = 0; k < 1024; k++)
+					test_log(DBG_LVL_VERBOSE, "%d:0x%x ", k,
+						 *(test_ctxt.rx_buff + k));
+
+				test_log(DBG_LVL_VERBOSE, "\n");
+
+				test_log(DBG_LVL_INFO,
+					 "CompareRxTx: finished iterations %i\n",
+					completed_iterations);
+				test_log(DBG_LVL_INFO,
+					 "CompareRxTx: Total pkts sent %u\n",
+					test_ctxt.tx_pkt_count);
+
+				curr_ptr = 0;
+				force_exit = true;
+				cmp_rxtx_status = TEST_STATUS_ERROR;
+				pthread_exit(&cmp_rxtx_status);
+				return NULL;
+			}
+
+			test_log(DBG_LVL_VERBOSE,
+			"CompareRxTx: Bytes Sent 0x%x, Received 0x%x\n",
+			*(test_ctxt.tx_buff + curr_ptr),
+			*(test_ctxt.rx_buff + curr_ptr));
+			curr_ptr++;
+		}
+
+		/*
+		 * completion will start as true and change depending if the
+		 * iterations has been completed for all client threads
+		 */
+		if (curr_ptr >= test_ctxt.byte_sent)
+			completion = (completion && test_ctxt.iter_complete);
+		else
+			completion = false;
+
+		/*
+		 * Once all client threads have finished their iteration, reset
+		 * everything and allow the client thread to start their next
+		 * iteration
+		 */
+		if (completion) {
+			test_ctxt.byte_sent = 0;
+			__sync_synchronize();
+			test_ctxt.byte_recvd = 0;
+			test_ctxt.iter_complete = false;
+			test_ctxt.comp_complete = true;
+			curr_ptr = 0;
+			test_log(DBG_LVL_INFO, "CompareRxTx: TX and RX match\n");
+		} else {
+			completion = true;
+		}
+	}
+}
+
+static void loopback_test_display_err_data(void)
+{
+	test_log(DBG_LVL_ERROR, "Wrote %lu bytes out of a %lu buff size\n",
+		 test_ctxt.byte_sent, test_ctxt.buff_size);
+	test_log(DBG_LVL_ERROR, "Remaining bytes to write %lu\n",
+		 (test_ctxt.buff_size - test_ctxt.byte_sent));
+}
+
+static enum test_status loopback_test_setup_write_packet(void)
+{
+	bool poll_timeout = true;
+
+	if (loopback_test_poll(&write_fd, poll_timeout) == TEST_STATUS_ERROR)
+		return TEST_STATUS_ERROR;
+
+	test_log(DBG_LVL_VERBOSE, "revents: %d\n", write_fd.revents);
+
+	if (write_fd.revents & POLLOUT) {
+		memset(test_ctxt.tx_buff + test_ctxt.byte_sent, write_data,
+		       test_ctxt.buff_size);
+		test_log(DBG_LVL_VERBOSE, "Write %02x of size %lu\n", write_data,
+			 test_ctxt.buff_size);
+
+		if (loopback_test_write(&write_fd) != TEST_STATUS_SUCCESS) {
+			loopback_test_sleep_ms(1000);
+			return TEST_STATUS_ERROR;
+		}
+
+		test_log(DBG_LVL_INFO, "Total byte_sent %li\n",
+			 test_ctxt.byte_sent);
+		write_fd.revents = 0;
+	}
+
+	return TEST_STATUS_SUCCESS;
+}
+
+static enum test_status loopback_test_wait_to_get_bytes_back(void)
+{
+	int time_count = 0;
+
+	test_log(DBG_LVL_INFO, "Sent %li bytes, received %li bytes\n",
+		 test_ctxt.byte_sent, test_ctxt.byte_recvd);
+
+	/* read thread will fill bytesRec and wait till it equals byte_sent */
+	while (test_ctxt.byte_recvd != test_ctxt.byte_sent) {
+		if (loopback_test_time_out(&time_count) == TEST_STATUS_ERROR)
+			return TEST_STATUS_ERROR;
+	}
+
+	return TEST_STATUS_SUCCESS;
+}
+
+static void *loopback_test_tx(void *data)
+{
+	int i;
+	int time_count = 0;
+	int failed_iterations = 0;
+	enum test_status status = TEST_STATUS_SUCCESS;
+
+	tx_status = TEST_STATUS_SUCCESS;
+
+	for (i = 0; i < test_ctxt.iterations; i++) {
+		loopback_test_reset_ctxt();
+
+		test_ctxt.iter_complete = false;
+
+		/* While the bytes sent is less than the buffsize */
+		while (((unsigned int)test_ctxt.byte_sent < test_ctxt.buff_size)
+			&& (status == TEST_STATUS_SUCCESS)) {
+			if (force_exit == true)
+				goto exit;
+
+			if (status != TEST_STATUS_SUCCESS) {
+				loopback_test_display_err_data();
+				tx_status = TEST_STATUS_ERROR;
+				goto exit;
+			}
+
+			status = loopback_test_setup_write_packet();
+			if (status == TEST_STATUS_ERROR) {
+				test_log(DBG_LVL_INFO,
+					 "Failed after %d iterations\n", i);
+				failed_iterations++;
+				goto exit;
+			}
+		}
+
+		if (loopback_test_wait_to_get_bytes_back() ==
+			TEST_STATUS_ERROR) {
+			tx_status = TEST_STATUS_ERROR;
+			goto exit;
+		}
+
+		__sync_synchronize();
+
+		test_ctxt.iter_complete = true;
+
+		while (!test_ctxt.comp_complete) {
+			if (loopback_test_time_out(&time_count) ==
+				TEST_STATUS_ERROR) {
+				tx_status = TEST_STATUS_ERROR;
+				goto exit;
+			}
+		}
+		time_count = 0;
+	}
+
+	if (failed_iterations > 0)
+		test_log(DBG_LVL_INFO, "Amount of Failed Iterations: %d\n",
+			 failed_iterations);
+
+exit:
+	loopback_test_reset_ctxt();
+
+	/* all of the iterations for this client thread have been completed */
+	test_ctxt.test_complete = true;
+
+	/* close the opened file descriptors */
+	loopback_test_close(&write_fd, &read_fd);
+
+	test_log(DBG_LVL_INFO, "mhi_test_loopback: exiting thread\n");
+
+	pthread_exit(&tx_status);
+
+	return NULL;
+}
+
+/*
+ * This function will be called when the user wishes to perform a loopback test.
+ * In this function, a compare thread will be created to compare the tx buffer
+ * and the rx Buffer. Device file node is opened for write and read. Tx thread
+ * is created to send data and Rx thread to receive data.
+ */
+enum test_status loopback_test_thread_create(void)
+{
+	int i = 0;
+	enum test_status status = TEST_STATUS_SUCCESS;
+	enum test_status *write_thread_retval;
+	enum test_status *read_thread_retval;
+	enum test_status *compare_thread_retval;
+
+	pthread_t compare_rx_tx_thread;
+	pthread_t loopback_thread;
+	pthread_t receive_thread;
+
+	/* set all tests (including open/close) to not completed */
+	test_ctxt.all_complete = false;
+
+	/* set current test to not completed */
+	test_ctxt.test_complete = false;
+
+	if (loopback_test_alloc_rx_tx_buff() == TEST_STATUS_ERROR) {
+		status = TEST_STATUS_ERROR;
+		goto exit;
+	}
+
+	/* Create thread for comparing the rx and tx buffers */
+	if (pthread_create(&compare_rx_tx_thread, NULL,
+			   loopback_test_compare_rxtx, NULL) != 0) {
+		test_log(DBG_LVL_ERROR, "Error creating compare thread\n");
+		status = TEST_STATUS_ERROR;
+		goto exit;
+	}
+
+	test_log(DBG_LVL_INFO, "dev_node: %s\n", test_ctxt.dev_node);
+
+	/* closing the device node will happen in the loopback thread */
+	status = loopback_test_open(&write_fd, &read_fd, test_ctxt.dev_node);
+	if (status == TEST_STATUS_ERROR) {
+		test_log(DBG_LVL_ERROR, "Failed to open device node\n");
+		goto exit;
+	}
+
+	/* Spawn the loopback tx thread */
+	if (pthread_create(&loopback_thread, NULL, loopback_test_tx, NULL)
+			   != 0) {
+		test_log(DBG_LVL_ERROR, "Error creating tx thread");
+		status = TEST_STATUS_ERROR;
+		goto exit;
+	}
+
+	/* Create thread for receiving packets */
+	if (pthread_create(&receive_thread, NULL, loopback_test_rx, NULL)
+			   != 0) {
+		test_log(DBG_LVL_ERROR, "Error creating rx thread\n");
+		status = TEST_STATUS_ERROR;
+		goto exit;
+	}
+
+	test_log(DBG_LVL_INFO, "Waiting for Tx and Rx threads to complete\n");
+
+	/* wait till all client and receive threads have finished */
+	pthread_join(loopback_thread, (void **)(&write_thread_retval));
+	pthread_join(receive_thread, (void **)(&read_thread_retval));
+
+	test_log(DBG_LVL_VERBOSE, "TX and Rx threads completed\n");
+
+	test_log(DBG_LVL_INFO, "Write thread status: %s\n",
+		 *write_thread_retval ? "Fail" : "Pass");
+	test_log(DBG_LVL_INFO, "Read thread status: %s\n",
+		 *read_thread_retval ? "Fail" : "Pass");
+
+	if ((*write_thread_retval == TEST_STATUS_ERROR) ||
+	    (*read_thread_retval == TEST_STATUS_ERROR)) {
+		test_log(DBG_LVL_ERROR, "Returned error, exiting\n");
+		status = TEST_STATUS_ERROR;
+		goto exit;
+	}
+
+	test_log(DBG_LVL_INFO, "Thread %i of tests complete\n", i);
+	test_ctxt.test_complete = false;
+
+	test_log(DBG_LVL_INFO, "All loopback threads completed\n");
+
+	test_ctxt.all_complete = true;
+
+	test_log(DBG_LVL_INFO, "Waiting for comp thread to exit\n");
+
+	pthread_join(compare_rx_tx_thread, (void **)(&compare_thread_retval));
+	if (*compare_thread_retval == TEST_STATUS_ERROR) {
+		test_log(DBG_LVL_ERROR, "Compare thread returned error\n");
+		status = TEST_STATUS_ERROR;
+	}
+
+exit:
+	/* All threads have finished using the Tx and Rx Buffers, free them */
+	free(test_ctxt.tx_buff);
+	test_ctxt.tx_buff = NULL;
+	free(test_ctxt.rx_buff);
+	test_ctxt.rx_buff = NULL;
+
+	return status;
+}
+
+static void *loopback_test_run(void *data)
+{
+	enum test_status status = TEST_STATUS_SUCCESS;
+
+	force_exit = false;
+	srand(time(NULL));
+
+	status = loopback_test_thread_create();
+
+	pthread_exit(&status);
+
+	return NULL;
+}
+
+static void loopback_test_set_defaults(void)
+{
+	msg_lvl = DBG_LVL_INFO;
+
+	memset(&test_ctxt, 0, sizeof(test_ctxt));
+	test_ctxt.iterations = 1;
+	test_ctxt.buff_size = 1024;
+}
+
+static void usage(void)
+{
+	test_log(DBG_LVL_INFO, "\nUsage:\n");
+	test_log(DBG_LVL_INFO, "-c: Device node\n");
+	test_log(DBG_LVL_INFO, "-b: Buffer size (default: 1024 bytes)\n");
+	test_log(DBG_LVL_INFO, "-i: Number of iterations\n");
+	test_log(DBG_LVL_INFO, "-l: log level, default - 1\n");
+	test_log(DBG_LVL_INFO, "log level : 0 -verbose, 1 -info , 2 -err\n");
+}
+
+static int loopback_test_parse(int argc, char *argv[])
+{
+	int i = 0;
+	int command = 0;
+	int indexptr = 0;
+	char *optstr = "-:c:b:i:l:";
+	int *return_value = NULL;
+	int status = -EINVAL;
+	pthread_t run_test;
+
+	optind = 1;
+
+	static const struct option optlongstr[] = {
+			{ "device node", required_argument, NULL, 'c'},
+			{0, 0, 0, 0}
+	};
+
+	test_log(DBG_LVL_INFO, "\nStarting MHI loopback tests\n");
+
+	test_log(DBG_LVL_VERBOSE, "argc: %d\n", argc);
+	for (i = 0; i < argc; i++)
+		test_log(DBG_LVL_VERBOSE, "argv[%i] = %s; ", i, argv[i]);
+
+	while ((command = getopt_long(argc, (char **)argv, optstr, optlongstr,
+				      &indexptr)) && (command != -1)) {
+		switch (command) {
+		case 'c':
+			sprintf(test_ctxt.dev_node, "%s", optarg);
+			test_log(DBG_LVL_INFO, "%s\n", test_ctxt.dev_node);
+			break;
+		case 'b':
+			test_ctxt.buff_size = atoi(optarg);
+			test_log(DBG_LVL_INFO, "%lu\n", test_ctxt.buff_size);
+			break;
+		case 'i':
+			test_ctxt.iterations = atoi(optarg);
+			test_log(DBG_LVL_INFO, "%u\n", test_ctxt.iterations);
+			break;
+		case 'l':
+			msg_lvl = atoi(optarg);
+			test_log(DBG_LVL_INFO, "log level: %d\n", atoi(optarg));
+			break;
+		default:
+			test_log(DBG_LVL_ERROR, "Invalid Option: %d\n",
+				 command);
+			usage();
+			return TEST_STATUS_ERROR;
+		}
+	}
+
+	if (pthread_create(&run_test, NULL, loopback_test_run, NULL) != 0) {
+		test_log(DBG_LVL_ERROR, "Error creating run_mhi_test\n");
+	} else {
+		pthread_join(run_test, (void **)(&return_value));
+
+		if (*return_value != TEST_STATUS_SUCCESS) {
+			test_log(DBG_LVL_ERROR, "Test Failed\n");
+		} else {
+			test_log(DBG_LVL_INFO, "Test Passed\n");
+			status = 0;
+		}
+	}
+
+	return status;
+}
+
+int main(int argc, char *argv[])
+{
+	int ret = 0;
+
+	loopback_test_set_defaults();
+	test_log(DBG_LVL_INFO, "MHI Loopback test App\n");
+
+	if (argc > 1)
+		ret = loopback_test_parse(argc, argv);
+	else
+		usage();
+
+	return ret;
+}
-- 
The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum,
a Linux Foundation Collaborative Project

Re: [PATCH v12 5/5] selftest: mhi: Add support to test MHI LOOPBACK channel

[Loic Poulain]

On Mon, 16 Nov 2020 at 23:46, Hemant Kumar <hemantk@codeaurora.org> wrote:
>
> Loopback test opens the MHI device file node and writes
> a data buffer to it. MHI UCI kernel space driver copies
> the data and sends it to MHI uplink (Tx) LOOPBACK channel.
> MHI device loops back the same data to MHI downlink (Rx)
> LOOPBACK channel. This data is read by test application
> and compared against the data sent. Test passes if data
> buffer matches between Tx and Rx. Test application performs
> open(), poll(), write(), read() and close() file operations.
>
> Signed-off-by: Hemant Kumar <hemantk@codeaurora.org>
> ---
>  Documentation/mhi/uci.rst                          |  32 +
>  tools/testing/selftests/Makefile                   |   1 +
>  tools/testing/selftests/drivers/.gitignore         |   1 +
>  tools/testing/selftests/drivers/mhi/Makefile       |   8 +
>  tools/testing/selftests/drivers/mhi/config         |   2 +
>  .../testing/selftests/drivers/mhi/loopback_test.c  | 802 +++++++++++++++++++++
>  6 files changed, 846 insertions(+)
>  create mode 100644 tools/testing/selftests/drivers/mhi/Makefile
>  create mode 100644 tools/testing/selftests/drivers/mhi/config
>  create mode 100644 tools/testing/selftests/drivers/mhi/loopback_test.c
>
> diff --git a/Documentation/mhi/uci.rst b/Documentation/mhi/uci.rst
> index ce8740e..0a04afe 100644
> --- a/Documentation/mhi/uci.rst
> +++ b/Documentation/mhi/uci.rst
> @@ -79,6 +79,38 @@ MHI client driver performs read operation, same data gets looped back to MHI
>  host using LOOPBACK channel 1. LOOPBACK channel is used to verify data path
>  and data integrity between MHI Host and MHI device.
>
> +Loopback Test
> +~~~~~~~~~~~~~
> +
> +Loopback test application is used to verify data integrity between MHI host and
> +MHI device over LOOPBACK channel. This also confirms that basic MHI data path
> +is working properly. Test performs write() to send tx buffer to MHI device file
> +node for LOOPBACK uplink channel. MHI LOOPBACK downlink channel loops back
> +transmit data to MHI Host. Test application receives data in receive buffer as
> +part of read(). It verifies if tx buffer matches rx buffer. Test application
> +performs poll() before making write() and read() system calls. Test passes if
> +match is found.
> +
> +Test is present under tools/testing/selftests/drivers/mhi. It is compiled using
> +following command in same dir:-
> +
> +make loopback_test
> +
> +Test is run using following command arguments:-
> +
> +loopback_test -c <device_node> -b <transmit buffer size> -l <log level> -i
> +<number of iterations>
> +
> +Required argument:
> +-c : loopback chardev node
> +
> +Optional argument:
> +-b : transmit buffer size. If not present 1024 bytes size transmit buffer
> +     is sent.
> +-i : Number of iterations to perform, If not present only one transmit buffer
> +     is sent.
> +-l : Log level. If not present defaults to DBG_LVL_INFO.
> +
>  Other Use Cases
>  ---------------
>
> diff --git a/tools/testing/selftests/Makefile b/tools/testing/selftests/Makefile
> index d9c2835..084bc1e 100644
> --- a/tools/testing/selftests/Makefile
> +++ b/tools/testing/selftests/Makefile
> @@ -10,6 +10,7 @@ TARGETS += core
>  TARGETS += cpufreq
>  TARGETS += cpu-hotplug
>  TARGETS += drivers/dma-buf
> +TARGETS += drivers/mhi
>  TARGETS += efivarfs
>  TARGETS += exec
>  TARGETS += filesystems
> diff --git a/tools/testing/selftests/drivers/.gitignore b/tools/testing/selftests/drivers/.gitignore
> index ca74f2e..e4806d5 100644
> --- a/tools/testing/selftests/drivers/.gitignore
> +++ b/tools/testing/selftests/drivers/.gitignore
> @@ -1,2 +1,3 @@
>  # SPDX-License-Identifier: GPL-2.0-only
>  /dma-buf/udmabuf
> +/mhi/loopback_test
> diff --git a/tools/testing/selftests/drivers/mhi/Makefile b/tools/testing/selftests/drivers/mhi/Makefile
> new file mode 100644
> index 0000000..c06c925
> --- /dev/null
> +++ b/tools/testing/selftests/drivers/mhi/Makefile
> @@ -0,0 +1,8 @@
> +# SPDX-License-Identifier: GPL-2.0-only
> +CFLAGS += -I../../../../../usr/include/ -g -Wall
> +
> +LDLIBS = -lpthread
> +TEST_GEN_PROGS := loopback_test
> +
> +include ../../lib.mk
> +
> diff --git a/tools/testing/selftests/drivers/mhi/config b/tools/testing/selftests/drivers/mhi/config
> new file mode 100644
> index 0000000..471dc92
> --- /dev/null
> +++ b/tools/testing/selftests/drivers/mhi/config
> @@ -0,0 +1,2 @@
> +CONFIG_MHI_BUS=y
> +CONFIG_MHi_UCI=y

CONFIG_MHI_UCI

> diff --git a/tools/testing/selftests/drivers/mhi/loopback_test.c b/tools/testing/selftests/drivers/mhi/loopback_test.c
> new file mode 100644
> index 0000000..99b7712
> --- /dev/null
> +++ b/tools/testing/selftests/drivers/mhi/loopback_test.c
> @@ -0,0 +1,802 @@
> +// SPDX-License-Identifier: GPL-2.0

[...]

Re: [PATCH v12 5/5] selftest: mhi: Add support to test MHI LOOPBACK channel

[Manivannan Sadhasivam]

On Mon, Nov 16, 2020 at 02:46:22PM -0800, Hemant Kumar wrote:
> Loopback test opens the MHI device file node and writes
> a data buffer to it. MHI UCI kernel space driver copies
> the data and sends it to MHI uplink (Tx) LOOPBACK channel.
> MHI device loops back the same data to MHI downlink (Rx)
> LOOPBACK channel. This data is read by test application
> and compared against the data sent. Test passes if data
> buffer matches between Tx and Rx. Test application performs
> open(), poll(), write(), read() and close() file operations.
> 
> Signed-off-by: Hemant Kumar <hemantk@codeaurora.org>

One nitpick below, with that addressed:

Reviewed-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>

> ---
>  Documentation/mhi/uci.rst                          |  32 +
>  tools/testing/selftests/Makefile                   |   1 +
>  tools/testing/selftests/drivers/.gitignore         |   1 +
>  tools/testing/selftests/drivers/mhi/Makefile       |   8 +
>  tools/testing/selftests/drivers/mhi/config         |   2 +
>  .../testing/selftests/drivers/mhi/loopback_test.c  | 802 +++++++++++++++++++++
>  6 files changed, 846 insertions(+)
>  create mode 100644 tools/testing/selftests/drivers/mhi/Makefile
>  create mode 100644 tools/testing/selftests/drivers/mhi/config
>  create mode 100644 tools/testing/selftests/drivers/mhi/loopback_test.c
> 
> diff --git a/Documentation/mhi/uci.rst b/Documentation/mhi/uci.rst
> index ce8740e..0a04afe 100644
> --- a/Documentation/mhi/uci.rst
> +++ b/Documentation/mhi/uci.rst
> @@ -79,6 +79,38 @@ MHI client driver performs read operation, same data gets looped back to MHI
>  host using LOOPBACK channel 1. LOOPBACK channel is used to verify data path
>  and data integrity between MHI Host and MHI device.
>  
> +Loopback Test
> +~~~~~~~~~~~~~
> +
> +Loopback test application is used to verify data integrity between MHI host and
> +MHI device over LOOPBACK channel. This also confirms that basic MHI data path
> +is working properly. Test performs write() to send tx buffer to MHI device file
> +node for LOOPBACK uplink channel. MHI LOOPBACK downlink channel loops back
> +transmit data to MHI Host. Test application receives data in receive buffer as
> +part of read(). It verifies if tx buffer matches rx buffer. Test application
> +performs poll() before making write() and read() system calls. Test passes if
> +match is found.
> +
> +Test is present under tools/testing/selftests/drivers/mhi. It is compiled using
> +following command in same dir:-
> +
> +make loopback_test
> +
> +Test is run using following command arguments:-
> +
> +loopback_test -c <device_node> -b <transmit buffer size> -l <log level> -i
> +<number of iterations>
> +
> +Required argument:
> +-c : loopback chardev node
> +
> +Optional argument:
> +-b : transmit buffer size. If not present 1024 bytes size transmit buffer
> +     is sent.
> +-i : Number of iterations to perform, If not present only one transmit buffer
> +     is sent.
> +-l : Log level. If not present defaults to DBG_LVL_INFO.
> +
>  Other Use Cases
>  ---------------
>  
> diff --git a/tools/testing/selftests/Makefile b/tools/testing/selftests/Makefile
> index d9c2835..084bc1e 100644
> --- a/tools/testing/selftests/Makefile
> +++ b/tools/testing/selftests/Makefile
> @@ -10,6 +10,7 @@ TARGETS += core
>  TARGETS += cpufreq
>  TARGETS += cpu-hotplug
>  TARGETS += drivers/dma-buf
> +TARGETS += drivers/mhi
>  TARGETS += efivarfs
>  TARGETS += exec
>  TARGETS += filesystems
> diff --git a/tools/testing/selftests/drivers/.gitignore b/tools/testing/selftests/drivers/.gitignore
> index ca74f2e..e4806d5 100644
> --- a/tools/testing/selftests/drivers/.gitignore
> +++ b/tools/testing/selftests/drivers/.gitignore
> @@ -1,2 +1,3 @@
>  # SPDX-License-Identifier: GPL-2.0-only
>  /dma-buf/udmabuf
> +/mhi/loopback_test
> diff --git a/tools/testing/selftests/drivers/mhi/Makefile b/tools/testing/selftests/drivers/mhi/Makefile
> new file mode 100644
> index 0000000..c06c925
> --- /dev/null
> +++ b/tools/testing/selftests/drivers/mhi/Makefile
> @@ -0,0 +1,8 @@
> +# SPDX-License-Identifier: GPL-2.0-only
> +CFLAGS += -I../../../../../usr/include/ -g -Wall
> +
> +LDLIBS = -lpthread
> +TEST_GEN_PROGS := loopback_test
> +
> +include ../../lib.mk
> +
> diff --git a/tools/testing/selftests/drivers/mhi/config b/tools/testing/selftests/drivers/mhi/config
> new file mode 100644
> index 0000000..471dc92
> --- /dev/null
> +++ b/tools/testing/selftests/drivers/mhi/config
> @@ -0,0 +1,2 @@
> +CONFIG_MHI_BUS=y
> +CONFIG_MHi_UCI=y
> diff --git a/tools/testing/selftests/drivers/mhi/loopback_test.c b/tools/testing/selftests/drivers/mhi/loopback_test.c
> new file mode 100644
> index 0000000..99b7712
> --- /dev/null
> +++ b/tools/testing/selftests/drivers/mhi/loopback_test.c
> @@ -0,0 +1,802 @@
> +

[...]

> +int main(int argc, char *argv[])
> +{
> +	int ret = 0;
> +
> +	loopback_test_set_defaults();
> +	test_log(DBG_LVL_INFO, "MHI Loopback test App\n");
> +
> +	if (argc > 1)
> +		ret = loopback_test_parse(argc, argv);

Effectively this functions does parse and run, so this should be called
as, "loopback_test_parse_run" or pthread creation should be moved here.

Thanks,
Mani

> +	else
> +		usage();
> +
> +	return ret;
> +}
> -- 
> The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum,
> a Linux Foundation Collaborative Project
> 

Re: [PATCH v12 5/5] selftest: mhi: Add support to test MHI LOOPBACK channel

[Hemant Kumar]

Hi Mani,
On 11/19/20 10:10 PM, Manivannan Sadhasivam wrote:
> On Mon, Nov 16, 2020 at 02:46:22PM -0800, Hemant Kumar wrote:
>> Loopback test opens the MHI device file node and writes
>> a data buffer to it. MHI UCI kernel space driver copies
>> the data and sends it to MHI uplink (Tx) LOOPBACK channel.
>> MHI device loops back the same data to MHI downlink (Rx)
>> LOOPBACK channel. This data is read by test application
>> and compared against the data sent. Test passes if data
>> buffer matches between Tx and Rx. Test application performs
>> open(), poll(), write(), read() and close() file operations.
>>
>> Signed-off-by: Hemant Kumar <hemantk@codeaurora.org>
> 
> One nitpick below, with that addressed:
> 
> Reviewed-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
[..]
> 
> Effectively this functions does parse and run, so this should be called
> as, "loopback_test_parse_run" or pthread creation should be moved here.
Done.

-- 
The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum,
a Linux Foundation Collaborative Project

Re: [PATCH v12 5/5] selftest: mhi: Add support to test MHI LOOPBACK channel

[Shuah Khan]

On 11/16/20 3:46 PM, Hemant Kumar wrote:
> Loopback test opens the MHI device file node and writes
> a data buffer to it. MHI UCI kernel space driver copies
> the data and sends it to MHI uplink (Tx) LOOPBACK channel.
> MHI device loops back the same data to MHI downlink (Rx)
> LOOPBACK channel. This data is read by test application
> and compared against the data sent. Test passes if data
> buffer matches between Tx and Rx. Test application performs
> open(), poll(), write(), read() and close() file operations.
> 
> Signed-off-by: Hemant Kumar <hemantk@codeaurora.org>
> ---
>   Documentation/mhi/uci.rst                          |  32 +
>   tools/testing/selftests/Makefile                   |   1 +
>   tools/testing/selftests/drivers/.gitignore         |   1 +
>   tools/testing/selftests/drivers/mhi/Makefile       |   8 +
>   tools/testing/selftests/drivers/mhi/config         |   2 +
>   .../testing/selftests/drivers/mhi/loopback_test.c  | 802 +++++++++++++++++++++
>   6 files changed, 846 insertions(+)
>   create mode 100644 tools/testing/selftests/drivers/mhi/Makefile
>   create mode 100644 tools/testing/selftests/drivers/mhi/config
>   create mode 100644 tools/testing/selftests/drivers/mhi/loopback_test.c
> 
> diff --git a/Documentation/mhi/uci.rst b/Documentation/mhi/uci.rst
> index ce8740e..0a04afe 100644
> --- a/Documentation/mhi/uci.rst
> +++ b/Documentation/mhi/uci.rst
> @@ -79,6 +79,38 @@ MHI client driver performs read operation, same data gets looped back to MHI
>   host using LOOPBACK channel 1. LOOPBACK channel is used to verify data path
>   and data integrity between MHI Host and MHI device.
>   

Nice.

> +Loopback Test
> +~~~~~~~~~~~~~
> +
> +Loopback test application is used to verify data integrity between MHI host and
> +MHI device over LOOPBACK channel. This also confirms that basic MHI data path
> +is working properly. Test performs write() to send tx buffer to MHI device file
> +node for LOOPBACK uplink channel. MHI LOOPBACK downlink channel loops back
> +transmit data to MHI Host. Test application receives data in receive buffer as
> +part of read(). It verifies if tx buffer matches rx buffer. Test application
> +performs poll() before making write() and read() system calls. Test passes if
> +match is found.
> +
> +Test is present under tools/testing/selftests/drivers/mhi. It is compiled using
> +following command in same dir:-
> +
> +make loopback_test
> +
> +Test is run using following command arguments:-
> +
> +loopback_test -c <device_node> -b <transmit buffer size> -l <log level> -i
> +<number of iterations>
> +
> +Required argument:
> +-c : loopback chardev node
> +
> +Optional argument:
> +-b : transmit buffer size. If not present 1024 bytes size transmit buffer
> +     is sent.
> +-i : Number of iterations to perform, If not present only one transmit buffer
> +     is sent.
> +-l : Log level. If not present defaults to DBG_LVL_INFO.
> +
>   Other Use Cases
>   ---------------
>   
> diff --git a/tools/testing/selftests/Makefile b/tools/testing/selftests/Makefile
> index d9c2835..084bc1e 100644
> --- a/tools/testing/selftests/Makefile
> +++ b/tools/testing/selftests/Makefile
> @@ -10,6 +10,7 @@ TARGETS += core
>   TARGETS += cpufreq
>   TARGETS += cpu-hotplug
>   TARGETS += drivers/dma-buf
> +TARGETS += drivers/mhi
>   TARGETS += efivarfs
>   TARGETS += exec
>   TARGETS += filesystems
> diff --git a/tools/testing/selftests/drivers/.gitignore b/tools/testing/selftests/drivers/.gitignore
> index ca74f2e..e4806d5 100644
> --- a/tools/testing/selftests/drivers/.gitignore
> +++ b/tools/testing/selftests/drivers/.gitignore
> @@ -1,2 +1,3 @@
>   # SPDX-License-Identifier: GPL-2.0-only
>   /dma-buf/udmabuf
> +/mhi/loopback_test
> diff --git a/tools/testing/selftests/drivers/mhi/Makefile b/tools/testing/selftests/drivers/mhi/Makefile
> new file mode 100644
> index 0000000..c06c925
> --- /dev/null
> +++ b/tools/testing/selftests/drivers/mhi/Makefile
> @@ -0,0 +1,8 @@
> +# SPDX-License-Identifier: GPL-2.0-only
> +CFLAGS += -I../../../../../usr/include/ -g -Wall
> +
> +LDLIBS = -lpthread
> +TEST_GEN_PROGS := loopback_test
> +
> +include ../../lib.mk
> +
> diff --git a/tools/testing/selftests/drivers/mhi/config b/tools/testing/selftests/drivers/mhi/config
> new file mode 100644
> index 0000000..471dc92
> --- /dev/null
> +++ b/tools/testing/selftests/drivers/mhi/config
> @@ -0,0 +1,2 @@
> +CONFIG_MHI_BUS=y
> +CONFIG_MHi_UCI=y
> diff --git a/tools/testing/selftests/drivers/mhi/loopback_test.c b/tools/testing/selftests/drivers/mhi/loopback_test.c
> new file mode 100644
> index 0000000..99b7712
> --- /dev/null
> +++ b/tools/testing/selftests/drivers/mhi/loopback_test.c
> @@ -0,0 +1,802 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * Loopback test application performs write() to send tx buffer to MHI device
> + * file node for LOOPBACK uplink channel. MHI LOOPBACK downlink channel loops
> + * back transmit data to MHI Host. Test application receives data in receive
> + * buffer as part of read(). It verifies if tx buffer matches rx buffer. Test
> + * application performs poll() before making write() and read() system
> + * calls. Test passes if match is found.
> + *
> + * Test is compiled using following command:-
> + *
> + * make loopback_test
> + *
> + * Test is run using following command arguments:-
> + *
> + * loopback_test -c <device_node> -b <transmit buffer size> -l <log level> -i
> + * <number of iterations>
> + *
> + * Required argument:
> + * -c : loopback chardev node
> + *
> + * Optional argument:
> + * -b : transmit buffer size. If not present 1024 bytes size transmit buffer
> + *      is sent.
> + * -i : Number of iterations to perform, If not present only one transmit buffer
> + *      is sent.
> + * -l : Log level. If not present defaults to DBG_LVL_INFO.
> + */
> +
> +#include <errno.h>
> +#include <fcntl.h>
> +#include <getopt.h>
> +#include <pthread.h>
> +#include <stdbool.h>
> +#include <stdio.h>
> +#include <stdlib.h>
> +#include <string.h>
> +#include <sys/poll.h>
> +#include <unistd.h>
> +
> +enum debug_level {
> +	DBG_LVL_VERBOSE,
> +	DBG_LVL_INFO,
> +	DBG_LVL_ERROR,
> +};
> +
> +enum test_status {
> +	TEST_STATUS_SUCCESS,
> +	TEST_STATUS_ERROR,
> +	TEST_STATUS_NO_DEV,
> +};
> +

Since you are running this test as part of kselftest, please use
ksft errors nd returns.

> +struct lb_test_ctx {
> +	char dev_node[256];
> +	unsigned char *tx_buff;
> +	unsigned char *rx_buff;
> +	unsigned int rx_pkt_count;
> +	unsigned int tx_pkt_count;
> +	int iterations;
> +	bool iter_complete;
> +	bool comp_complete;
> +	bool test_complete;
> +	bool all_complete;
> +	unsigned long buff_size;
> +	long byte_recvd;
> +	long byte_sent;
> +};
> +
> +bool force_exit;
> +char write_data = 'a';
> +int completed_iterations;
> +
> +struct lb_test_ctx test_ctxt;
> +enum debug_level msg_lvl;
> +struct pollfd read_fd;
> +struct pollfd write_fd;
> +enum test_status mhi_test_return_value;
> +enum test_status tx_status;
> +enum test_status rx_status;
> +enum test_status cmp_rxtx_status;
> +
> +#define test_log(test_msg_lvl, format, ...) do { \
> +		if (test_msg_lvl >= msg_lvl) \
> +			fprintf(stderr, format, ##__VA_ARGS__); \
> +} while (0)
> +
> +static void loopback_test_sleep_ms(int ms)
> +{
> +	usleep(1000 * ms);
> +}
> +

Have you run this as part of "make kselftest" run. How does this
sleep work in that env.?

> +static enum test_status loopback_test_open(struct pollfd *write_fd,
> +					struct pollfd *read_fd, char *dev_name)
> +{
> +	enum test_status ret_val = TEST_STATUS_SUCCESS;
> +
> +	write_fd->fd = open(dev_name, O_SYNC | O_WRONLY);
> +	if (write_fd->fd < 0) {
> +		test_log(DBG_LVL_ERROR, "Error opening file for w: errno: %d\n", errno);
> +		ret_val = TEST_STATUS_ERROR;
> +	} else {
> +		test_log(DBG_LVL_INFO, "Opened %s, return code: %i.\n",
> +			 dev_name, write_fd->fd);
> +		write_fd->events = POLLOUT;
> +	}
> +
> +	read_fd->fd = open(dev_name, O_SYNC | O_RDONLY);
> +	if (read_fd->fd < 0) {
> +		test_log(DBG_LVL_ERROR, "Error opening file for r: errno: %d\n", errno);
> +		ret_val = TEST_STATUS_ERROR;
> +	} else {
> +		test_log(DBG_LVL_INFO, "Opened %s, return code: %i.\n",
> +			 dev_name, read_fd->fd);
> +		read_fd->events = POLLIN;
> +	}
> +
> +	return ret_val;
> +}
> +
> +static enum test_status loopback_test_close(struct pollfd *write_fd,
> +						 struct pollfd *read_fd)
> +{
> +	enum test_status ret_val = TEST_STATUS_SUCCESS;
> +
> +	if (close(read_fd->fd) == 0) {
> +		test_log(DBG_LVL_INFO, "Closed device handle\n");
> +	} else {
> +		test_log(DBG_LVL_ERROR, "Unable to close handle to device\n");
> +		ret_val = TEST_STATUS_ERROR;
> +	}
> +
> +	if (close(write_fd->fd) == 0) {
> +		test_log(DBG_LVL_INFO, "Closed device handle\n");
> +	} else {
> +		test_log(DBG_LVL_ERROR, "Unable to close handle to device\n");
> +		ret_val = TEST_STATUS_ERROR;
> +	}
> +

This should match the KSFT error codes

> +	return ret_val;
> +}
> +
> +static enum test_status loopback_test_alloc_rx_tx_buff(void)
> +{
> +	test_ctxt.rx_buff = (unsigned char *)malloc(test_ctxt.buff_size);
> +	if (!test_ctxt.rx_buff) {
> +		test_log(DBG_LVL_ERROR, "Failed to allocate rx buff\n");
> +		return TEST_STATUS_ERROR;
> +	}
> +
> +	memset(test_ctxt.rx_buff, 0x00, sizeof(test_ctxt.buff_size));
> +	test_ctxt.tx_buff = (unsigned char *)malloc(test_ctxt.buff_size);
> +	if (!test_ctxt.tx_buff) {
> +		test_log(DBG_LVL_ERROR, "Failed to allocate tx buff\n");
> +		return TEST_STATUS_ERROR;
> +	}
> +
> +	return TEST_STATUS_SUCCESS;
> +}
> +
> +static enum test_status loopback_test_write(struct pollfd *write_fd)
> +{
> +	enum test_status ret_value = TEST_STATUS_SUCCESS;
> +	signed long temp_bytes_sent = 0;
> +	signed long total_bytes_sent = 0;
> +
> +	test_log(DBG_LVL_VERBOSE, "About to write %lu\n", test_ctxt.buff_size);
> +
> +	temp_bytes_sent = write(write_fd->fd,
> +		test_ctxt.tx_buff + test_ctxt.byte_sent, test_ctxt.buff_size);
> +
> +	test_log(DBG_LVL_VERBOSE, "Returned %li\n", temp_bytes_sent);
> +	test_log(DBG_LVL_INFO, "Wrote packet with %li bytes of %02x\n",
> +		 temp_bytes_sent, *(test_ctxt.tx_buff + test_ctxt.byte_sent));
> +
> +	if (temp_bytes_sent < 0) {
> +		/* write returned a negative value i.e. write failed */
> +		test_log(DBG_LVL_ERROR, "write() failed: err code %d\n", errno);
> +		return TEST_STATUS_ERROR;
> +	}
> +
> +	if ((unsigned long)temp_bytes_sent > test_ctxt.buff_size) {
> +		test_log(DBG_LVL_ERROR, "Wrote more bytes than intended\n");
> +		return TEST_STATUS_ERROR;
> +	}
> +
> +	if (temp_bytes_sent == 0) {
> +		loopback_test_sleep_ms(10);
> +	} else if (temp_bytes_sent > 0) {
> +		test_ctxt.tx_pkt_count++;
> +		test_ctxt.byte_sent += temp_bytes_sent;
> +		total_bytes_sent += temp_bytes_sent;
> +		test_log(DBG_LVL_INFO, "Total written packets %d\n",
> +			 test_ctxt.tx_pkt_count);
> +	}
> +
> +	return ret_value;
> +}
> +
> +static void loopback_test_reset_ctxt(void)
> +{
> +	test_ctxt.byte_sent = 0;
> +	__sync_synchronize();
> +	test_ctxt.byte_recvd = 0;
> +	test_ctxt.rx_pkt_count = 0;
> +	test_ctxt.tx_pkt_count = 0;
> +	test_ctxt.comp_complete = false;
> +	memset((void *)test_ctxt.rx_buff, 0x00, test_ctxt.buff_size);
> +}
> +
> +static enum test_status loopback_test_time_out(int *time_count)
> +{
> +	enum test_status ret_val = TEST_STATUS_SUCCESS;
> +
> +	loopback_test_sleep_ms(3);
> +	if ((++*time_count) > 100000) {
> +		test_log(DBG_LVL_ERROR, "Error: all bytes not received for this iteration\n");
> +		ret_val = TEST_STATUS_ERROR;
> +		while (1)
> +			loopback_test_sleep_ms(1000);
> +	}
> +
> +	return ret_val;
> +}
> +
> +static enum test_status loopback_test_poll(struct pollfd *fd,
> +						bool poll_timeout)
> +{
> +	enum test_status ret_val = TEST_STATUS_SUCCESS;
> +	int poll_return = 0;
> +	int i = 0;
> +	int timeout = 1000; /* poll-wait 1 second */
> +	int file_desc_type = -1;
> +
> +	if (fd->events == POLLIN) {
> +		file_desc_type = 1; /* read */
> +		test_log(DBG_LVL_VERBOSE,
> +			 "Poll: opened read handle to device\n");
> +	} else if (fd->events == POLLOUT) {
> +		file_desc_type = 0; /* write */
> +		test_log(DBG_LVL_VERBOSE,
> +			 "Poll: opened write handle to device\n");
> +	}
> +
> +	if (poll_timeout == false)
> +		timeout = -1; /* poll-wait forever */
> +
> +	while (ret_val == TEST_STATUS_SUCCESS) {
> +		if (force_exit == true) {
> +			ret_val = TEST_STATUS_ERROR;
> +		} else {
> +			test_log(DBG_LVL_VERBOSE, "%s Polling %i\n",
> +				 file_desc_type ? "Read" : "Write", i);
> +
> +			poll_return = poll(fd, 1, timeout);
> +			if (poll_return == -1) {
> +				test_log(DBG_LVL_ERROR, "%s Poll error - %d\n",
> +					 file_desc_type ? "Read" : "Write",
> +					 errno);
> +				return TEST_STATUS_ERROR;
> +			} else if (((file_desc_type == 1) &&
> +				   (fd->revents & POLLIN)) ||
> +				   ((file_desc_type == 0) &&
> +				   (fd->revents & POLLOUT))) {
> +				test_log(DBG_LVL_VERBOSE,
> +					 "%s Poll Returned\n",
> +					 file_desc_type ? "Read" : "Write");
> +				return TEST_STATUS_SUCCESS;
> +			} else if (poll_timeout == true) {
> +				i++;
> +				poll_return = 0;
> +				if (i >= 250) {
> +					test_log(DBG_LVL_ERROR,
> +						 "Poll: %s Timed out: 10s\n",
> +					file_desc_type ? "Read" : "Write");
> +					return TEST_STATUS_ERROR;
> +				}
> +			}
> +
> +			loopback_test_sleep_ms(10);
> +		}
> +	}
> +
> +	return ret_val;
> +}
> +
> +static void *loopback_test_rx(void *data)
> +{
> +	bool poll_timeout = true;
> +	unsigned long read_size = test_ctxt.buff_size;
> +	long temp_bytes_rec;
> +	enum test_status status;
> +
> +	rx_status = TEST_STATUS_SUCCESS;
> +
> +	while (force_exit == false) {
> +		if (test_ctxt.test_complete) {
> +			test_log(DBG_LVL_INFO, "Rx: exiting thread\n");
> +			pthread_exit(&rx_status);
> +			return NULL;
> +		}
> +
> +		while ((test_ctxt.byte_sent > test_ctxt.byte_recvd) &&
> +		       (force_exit == false)) {
> +			test_log(DBG_LVL_VERBOSE,
> +				 "Rx: Bytes Sent: %li, Received %li\n",
> +				test_ctxt.byte_sent, test_ctxt.byte_recvd);
> +
> +			temp_bytes_rec = 0;
> +
> +			if (test_ctxt.comp_complete == false) {
> +				status = loopback_test_poll(&read_fd,
> +							    poll_timeout);
> +				if (status == TEST_STATUS_ERROR) {
> +					if (test_ctxt.test_complete == true)
> +						rx_status = TEST_STATUS_SUCCESS;
> +					else
> +						rx_status = TEST_STATUS_ERROR;
> +
> +					test_log(DBG_LVL_INFO,
> +						 "Rx: exiting thread\n");
> +					pthread_exit(&rx_status);
> +					return NULL;
> +				}
> +
> +				test_log(DBG_LVL_VERBOSE, "Rx: before read\n");
> +				temp_bytes_rec = read(read_fd.fd,
> +					test_ctxt.rx_buff + test_ctxt.byte_recvd,
> +					read_size);
> +				if (temp_bytes_rec < 0) {
> +					test_log(DBG_LVL_ERROR,
> +					"Rx: read() failed - err code %d\n",
> +					errno);
> +					rx_status = TEST_STATUS_ERROR;
> +					pthread_exit(&rx_status);
> +					return NULL;
> +				}
> +
> +				if (temp_bytes_rec == 0) {
> +					loopback_test_sleep_ms(10);
> +					rx_status = TEST_STATUS_ERROR;
> +					pthread_exit(&rx_status);
> +					return NULL;
> +				}
> +
> +				test_ctxt.rx_pkt_count++;
> +				test_log(DBG_LVL_INFO,
> +				"Rx: Read packet with %li bytes of %02x\n",
> +				temp_bytes_rec,
> +				*(test_ctxt.rx_buff + test_ctxt.byte_recvd));
> +				test_ctxt.byte_recvd += temp_bytes_rec;
> +				test_log(DBG_LVL_INFO,
> +					 "Rx: Total byte_recvd: %li\n",
> +					test_ctxt.byte_recvd);
> +				test_log(DBG_LVL_INFO,
> +					 "Rx: Total read packets %d\n",
> +					test_ctxt.rx_pkt_count);
> +				test_log(DBG_LVL_INFO,
> +					 "Rx: %lu byte buff_size\n",
> +					test_ctxt.buff_size);
> +
> +				read_fd.revents = 0;
> +			}
> +		}
> +	}
> +	rx_status = TEST_STATUS_ERROR;
> +	pthread_exit(&rx_status);
> +	return NULL;
> +}
> +
> +/* This single compare thread, will compare each byte of tx and rx Buff */
> +static void *loopback_test_compare_rxtx(void *data)
> +{
> +	int k;
> +	bool completion = true;
> +	long curr_ptr = 0;
> +
> +	test_log(DBG_LVL_INFO, "CompareRxTxThread: Inside thread\n");
> +	cmp_rxtx_status = TEST_STATUS_SUCCESS;
> +
> +	for (;;) {
> +		/* if the test is completed exit thread */
> +		if (test_ctxt.all_complete == true) {
> +			curr_ptr = 0;
> +			test_log(DBG_LVL_INFO,
> +				 "CompareRxTx: exiting thread\n");
> +			pthread_exit(&cmp_rxtx_status);
> +			return NULL;
> +		}
> +
> +		/* Simply compares each byte in each Tx and Rx buffer */
> +		while (curr_ptr < test_ctxt.byte_recvd) {
> +			if (*(test_ctxt.rx_buff + curr_ptr) !=
> +					*(test_ctxt.tx_buff + curr_ptr)) {
> +				test_log(DBG_LVL_ERROR,
> +					 "Mismatch Byte num %li\n", curr_ptr);
> +				test_log(DBG_LVL_ERROR,
> +					 "Bytes: Sent 0x%x, Received 0x%x\n",
> +					 *(test_ctxt.tx_buff + curr_ptr),
> +					 *(test_ctxt.rx_buff + curr_ptr));
> +				test_log(DBG_LVL_VERBOSE, "Rx buffer dump:\n");
> +				for (k = 0; k < 1024; k++)
> +					test_log(DBG_LVL_VERBOSE, "%d:0x%x ", k,
> +						 *(test_ctxt.rx_buff + k));
> +
> +				test_log(DBG_LVL_VERBOSE, "\n");
> +
> +				test_log(DBG_LVL_INFO,
> +					 "CompareRxTx: finished iterations %i\n",
> +					completed_iterations);
> +				test_log(DBG_LVL_INFO,
> +					 "CompareRxTx: Total pkts sent %u\n",
> +					test_ctxt.tx_pkt_count);
> +
> +				curr_ptr = 0;
> +				force_exit = true;
> +				cmp_rxtx_status = TEST_STATUS_ERROR;
> +				pthread_exit(&cmp_rxtx_status);
> +				return NULL;
> +			}
> +
> +			test_log(DBG_LVL_VERBOSE,
> +			"CompareRxTx: Bytes Sent 0x%x, Received 0x%x\n",
> +			*(test_ctxt.tx_buff + curr_ptr),
> +			*(test_ctxt.rx_buff + curr_ptr));
> +			curr_ptr++;
> +		}
> +
> +		/*
> +		 * completion will start as true and change depending if the
> +		 * iterations has been completed for all client threads
> +		 */
> +		if (curr_ptr >= test_ctxt.byte_sent)
> +			completion = (completion && test_ctxt.iter_complete);
> +		else
> +			completion = false;
> +
> +		/*
> +		 * Once all client threads have finished their iteration, reset
> +		 * everything and allow the client thread to start their next
> +		 * iteration
> +		 */
> +		if (completion) {
> +			test_ctxt.byte_sent = 0;
> +			__sync_synchronize();
> +			test_ctxt.byte_recvd = 0;
> +			test_ctxt.iter_complete = false;
> +			test_ctxt.comp_complete = true;
> +			curr_ptr = 0;
> +			test_log(DBG_LVL_INFO, "CompareRxTx: TX and RX match\n");
> +		} else {
> +			completion = true;
> +		}
> +	}
> +}
> +
> +static void loopback_test_display_err_data(void)
> +{
> +	test_log(DBG_LVL_ERROR, "Wrote %lu bytes out of a %lu buff size\n",
> +		 test_ctxt.byte_sent, test_ctxt.buff_size);
> +	test_log(DBG_LVL_ERROR, "Remaining bytes to write %lu\n",
> +		 (test_ctxt.buff_size - test_ctxt.byte_sent));
> +}
> +
> +static enum test_status loopback_test_setup_write_packet(void)
> +{
> +	bool poll_timeout = true;
> +
> +	if (loopback_test_poll(&write_fd, poll_timeout) == TEST_STATUS_ERROR)
> +		return TEST_STATUS_ERROR;
> +
> +	test_log(DBG_LVL_VERBOSE, "revents: %d\n", write_fd.revents);
> +
> +	if (write_fd.revents & POLLOUT) {
> +		memset(test_ctxt.tx_buff + test_ctxt.byte_sent, write_data,
> +		       test_ctxt.buff_size);
> +		test_log(DBG_LVL_VERBOSE, "Write %02x of size %lu\n", write_data,
> +			 test_ctxt.buff_size);
> +
> +		if (loopback_test_write(&write_fd) != TEST_STATUS_SUCCESS) {
> +			loopback_test_sleep_ms(1000);
> +			return TEST_STATUS_ERROR;
> +		}
> +
> +		test_log(DBG_LVL_INFO, "Total byte_sent %li\n",
> +			 test_ctxt.byte_sent);
> +		write_fd.revents = 0;
> +	}
> +
> +	return TEST_STATUS_SUCCESS;
> +}
> +
> +static enum test_status loopback_test_wait_to_get_bytes_back(void)
> +{
> +	int time_count = 0;
> +
> +	test_log(DBG_LVL_INFO, "Sent %li bytes, received %li bytes\n",
> +		 test_ctxt.byte_sent, test_ctxt.byte_recvd);
> +
> +	/* read thread will fill bytesRec and wait till it equals byte_sent */
> +	while (test_ctxt.byte_recvd != test_ctxt.byte_sent) {
> +		if (loopback_test_time_out(&time_count) == TEST_STATUS_ERROR)
> +			return TEST_STATUS_ERROR;
> +	}

Same here.

> +
> +	return TEST_STATUS_SUCCESS;
> +}
Here too

> +
> +static void *loopback_test_tx(void *data)
> +{
> +	int i;
> +	int time_count = 0;
> +	int failed_iterations = 0;
> +	enum test_status status = TEST_STATUS_SUCCESS;
> +
> +	tx_status = TEST_STATUS_SUCCESS;
> +
> +	for (i = 0; i < test_ctxt.iterations; i++) {
> +		loopback_test_reset_ctxt();
> +
> +		test_ctxt.iter_complete = false;
> +
> +		/* While the bytes sent is less than the buffsize */
> +		while (((unsigned int)test_ctxt.byte_sent < test_ctxt.buff_size)
> +			&& (status == TEST_STATUS_SUCCESS)) {
> +			if (force_exit == true)
> +				goto exit;
> +
> +			if (status != TEST_STATUS_SUCCESS) {
> +				loopback_test_display_err_data();
> +				tx_status = TEST_STATUS_ERROR;
> +				goto exit;
> +			}
> +
> +			status = loopback_test_setup_write_packet();
> +			if (status == TEST_STATUS_ERROR) {
> +				test_log(DBG_LVL_INFO,
> +					 "Failed after %d iterations\n", i);
> +				failed_iterations++;
> +				goto exit;
> +			}
> +		}
> +
> +		if (loopback_test_wait_to_get_bytes_back() ==
> +			TEST_STATUS_ERROR) {
> +			tx_status = TEST_STATUS_ERROR;
> +			goto exit;
> +		}
> +
> +		__sync_synchronize();
> +
> +		test_ctxt.iter_complete = true;
> +
> +		while (!test_ctxt.comp_complete) {
> +			if (loopback_test_time_out(&time_count) ==
> +				TEST_STATUS_ERROR) {
> +				tx_status = TEST_STATUS_ERROR;
> +				goto exit;
> +			}
> +		}
> +		time_count = 0;
> +	}
> +
> +	if (failed_iterations > 0)
> +		test_log(DBG_LVL_INFO, "Amount of Failed Iterations: %d\n",
> +			 failed_iterations);
> +
> +exit:
> +	loopback_test_reset_ctxt();
> +
> +	/* all of the iterations for this client thread have been completed */
> +	test_ctxt.test_complete = true;
> +
> +	/* close the opened file descriptors */
> +	loopback_test_close(&write_fd, &read_fd);
> +
> +	test_log(DBG_LVL_INFO, "mhi_test_loopback: exiting thread\n");
> +
> +	pthread_exit(&tx_status);
> +
> +	return NULL;
> +}
> +
> +/*
> + * This function will be called when the user wishes to perform a loopback test.
> + * In this function, a compare thread will be created to compare the tx buffer
> + * and the rx Buffer. Device file node is opened for write and read. Tx thread
> + * is created to send data and Rx thread to receive data.
> + */
> +enum test_status loopback_test_thread_create(void)
> +{
> +	int i = 0;
> +	enum test_status status = TEST_STATUS_SUCCESS;
> +	enum test_status *write_thread_retval;
> +	enum test_status *read_thread_retval;
> +	enum test_status *compare_thread_retval;
> +
> +	pthread_t compare_rx_tx_thread;
> +	pthread_t loopback_thread;
> +	pthread_t receive_thread;
> +
> +	/* set all tests (including open/close) to not completed */
> +	test_ctxt.all_complete = false;
> +
> +	/* set current test to not completed */
> +	test_ctxt.test_complete = false;
> +
> +	if (loopback_test_alloc_rx_tx_buff() == TEST_STATUS_ERROR) {
> +		status = TEST_STATUS_ERROR;
> +		goto exit;
> +	}
> +
> +	/* Create thread for comparing the rx and tx buffers */
> +	if (pthread_create(&compare_rx_tx_thread, NULL,
> +			   loopback_test_compare_rxtx, NULL) != 0) {
> +		test_log(DBG_LVL_ERROR, "Error creating compare thread\n");
> +		status = TEST_STATUS_ERROR;
> +		goto exit;
> +	}
> +
> +	test_log(DBG_LVL_INFO, "dev_node: %s\n", test_ctxt.dev_node);
> +
> +	/* closing the device node will happen in the loopback thread */
> +	status = loopback_test_open(&write_fd, &read_fd, test_ctxt.dev_node);
> +	if (status == TEST_STATUS_ERROR) {
> +		test_log(DBG_LVL_ERROR, "Failed to open device node\n");
> +		goto exit;
> +	}
> +
> +	/* Spawn the loopback tx thread */
> +	if (pthread_create(&loopback_thread, NULL, loopback_test_tx, NULL)
> +			   != 0) {
> +		test_log(DBG_LVL_ERROR, "Error creating tx thread");
> +		status = TEST_STATUS_ERROR;
> +		goto exit;
> +	}
> +
> +	/* Create thread for receiving packets */
> +	if (pthread_create(&receive_thread, NULL, loopback_test_rx, NULL)
> +			   != 0) {
> +		test_log(DBG_LVL_ERROR, "Error creating rx thread\n");
> +		status = TEST_STATUS_ERROR;
> +		goto exit;
> +	}
> +
> +	test_log(DBG_LVL_INFO, "Waiting for Tx and Rx threads to complete\n");
> +
> +	/* wait till all client and receive threads have finished */
> +	pthread_join(loopback_thread, (void **)(&write_thread_retval));
> +	pthread_join(receive_thread, (void **)(&read_thread_retval));
> +
> +	test_log(DBG_LVL_VERBOSE, "TX and Rx threads completed\n");
> +
> +	test_log(DBG_LVL_INFO, "Write thread status: %s\n",
> +		 *write_thread_retval ? "Fail" : "Pass");
> +	test_log(DBG_LVL_INFO, "Read thread status: %s\n",
> +		 *read_thread_retval ? "Fail" : "Pass");
> +
> +	if ((*write_thread_retval == TEST_STATUS_ERROR) ||
> +	    (*read_thread_retval == TEST_STATUS_ERROR)) {
> +		test_log(DBG_LVL_ERROR, "Returned error, exiting\n");
> +		status = TEST_STATUS_ERROR;
> +		goto exit;
> +	}
> +
> +	test_log(DBG_LVL_INFO, "Thread %i of tests complete\n", i);
> +	test_ctxt.test_complete = false;
> +
> +	test_log(DBG_LVL_INFO, "All loopback threads completed\n");
> +
> +	test_ctxt.all_complete = true;
> +
> +	test_log(DBG_LVL_INFO, "Waiting for comp thread to exit\n");
> +
> +	pthread_join(compare_rx_tx_thread, (void **)(&compare_thread_retval));
> +	if (*compare_thread_retval == TEST_STATUS_ERROR) {
> +		test_log(DBG_LVL_ERROR, "Compare thread returned error\n");
> +		status = TEST_STATUS_ERROR;
> +	}
> +
> +exit:
> +	/* All threads have finished using the Tx and Rx Buffers, free them */
> +	free(test_ctxt.tx_buff);
> +	test_ctxt.tx_buff = NULL;
> +	free(test_ctxt.rx_buff);
> +	test_ctxt.rx_buff = NULL;
> +
> +	return status;
> +}
> +
> +static void *loopback_test_run(void *data)
> +{
> +	enum test_status status = TEST_STATUS_SUCCESS;
> +
> +	force_exit = false;
> +	srand(time(NULL));
> +
> +	status = loopback_test_thread_create();
> +
> +	pthread_exit(&status);
> +
> +	return NULL;
> +}
> +
> +static void loopback_test_set_defaults(void)
> +{
> +	msg_lvl = DBG_LVL_INFO;
> +
> +	memset(&test_ctxt, 0, sizeof(test_ctxt));
> +	test_ctxt.iterations = 1;
> +	test_ctxt.buff_size = 1024;
> +}
> +
> +static void usage(void)
> +{
> +	test_log(DBG_LVL_INFO, "\nUsage:\n");
> +	test_log(DBG_LVL_INFO, "-c: Device node\n");
> +	test_log(DBG_LVL_INFO, "-b: Buffer size (default: 1024 bytes)\n");
> +	test_log(DBG_LVL_INFO, "-i: Number of iterations\n");
> +	test_log(DBG_LVL_INFO, "-l: log level, default - 1\n");
> +	test_log(DBG_LVL_INFO, "log level : 0 -verbose, 1 -info , 2 -err\n");
> +}
> +
> +static int loopback_test_parse(int argc, char *argv[])
> +{
> +	int i = 0;
> +	int command = 0;
> +	int indexptr = 0;
> +	char *optstr = "-:c:b:i:l:";
> +	int *return_value = NULL;
> +	int status = -EINVAL;
> +	pthread_t run_test;
> +
> +	optind = 1;
> +
> +	static const struct option optlongstr[] = {
> +			{ "device node", required_argument, NULL, 'c'},
> +			{0, 0, 0, 0}
> +	};
> +
> +	test_log(DBG_LVL_INFO, "\nStarting MHI loopback tests\n");
> +
> +	test_log(DBG_LVL_VERBOSE, "argc: %d\n", argc);
> +	for (i = 0; i < argc; i++)
> +		test_log(DBG_LVL_VERBOSE, "argv[%i] = %s; ", i, argv[i]);
> +
> +	while ((command = getopt_long(argc, (char **)argv, optstr, optlongstr,
> +				      &indexptr)) && (command != -1)) {
> +		switch (command) {
> +		case 'c':
> +			sprintf(test_ctxt.dev_node, "%s", optarg);
> +			test_log(DBG_LVL_INFO, "%s\n", test_ctxt.dev_node);
> +			break;
> +		case 'b':
> +			test_ctxt.buff_size = atoi(optarg);
> +			test_log(DBG_LVL_INFO, "%lu\n", test_ctxt.buff_size);
> +			break;
> +		case 'i':
> +			test_ctxt.iterations = atoi(optarg);
> +			test_log(DBG_LVL_INFO, "%u\n", test_ctxt.iterations);
> +			break;
> +		case 'l':
> +			msg_lvl = atoi(optarg);
> +			test_log(DBG_LVL_INFO, "log level: %d\n", atoi(optarg));
> +			break;
> +		default:
> +			test_log(DBG_LVL_ERROR, "Invalid Option: %d\n",
> +				 command);
> +			usage();
> +			return TEST_STATUS_ERROR;
> +		}
> +	}
> +
> +	if (pthread_create(&run_test, NULL, loopback_test_run, NULL) != 0) {
> +		test_log(DBG_LVL_ERROR, "Error creating run_mhi_test\n");
> +	} else {
> +		pthread_join(run_test, (void **)(&return_value));
> +
> +		if (*return_value != TEST_STATUS_SUCCESS) {
> +			test_log(DBG_LVL_ERROR, "Test Failed\n");
> +		} else {
> +			test_log(DBG_LVL_INFO, "Test Passed\n");
> +			status = 0;
> +		}
> +	}
> +
> +	return status;
> +}
> +
> +int main(int argc, char *argv[])
> +{
> +	int ret = 0;
> +
> +	loopback_test_set_defaults();
> +	test_log(DBG_LVL_INFO, "MHI Loopback test App\n");
> +
> +	if (argc > 1)
> +		ret = loopback_test_parse(argc, argv);
> +	else
> +		usage();
> +
> +	return ret;
> +}
> 

Are there any cases where this test can't run and have to - those
cases need to be skips.

thanks,
-- Shuah

Re: [PATCH v12 5/5] selftest: mhi: Add support to test MHI LOOPBACK channel

[Hemant Kumar]

Hi Shuah,

On 11/20/20 7:26 AM, Shuah Khan wrote:
> On 11/16/20 3:46 PM, Hemant Kumar wrote:
>> Loopback test opens the MHI device file node and writes
>> a data buffer to it. MHI UCI kernel space driver copies
>> the data and sends it to MHI uplink (Tx) LOOPBACK channel.
>> MHI device loops back the same data to MHI downlink (Rx)
>> LOOPBACK channel. This data is read by test application
>> and compared against the data sent. Test passes if data
>> buffer matches between Tx and Rx. Test application performs
>> open(), poll(), write(), read() and close() file operations.
>>
>> Signed-off-by: Hemant Kumar <hemantk@codeaurora.org>
>> ---
>>   Documentation/mhi/uci.rst                          |  32 +
>>   tools/testing/selftests/Makefile                   |   1 +
>>   tools/testing/selftests/drivers/.gitignore         |   1 +
>>   tools/testing/selftests/drivers/mhi/Makefile       |   8 +
>>   tools/testing/selftests/drivers/mhi/config         |   2 +
>>   .../testing/selftests/drivers/mhi/loopback_test.c  | 802 
>> +++++++++++++++++++++
>>   6 files changed, 846 insertions(+)
>>   create mode 100644 tools/testing/selftests/drivers/mhi/Makefile
>>   create mode 100644 tools/testing/selftests/drivers/mhi/config
>>   create mode 100644 tools/testing/selftests/drivers/mhi/loopback_test.c
>>
>> diff --git a/Documentation/mhi/uci.rst b/Documentation/mhi/uci.rst
>> index ce8740e..0a04afe 100644
>> --- a/Documentation/mhi/uci.rst
>> +++ b/Documentation/mhi/uci.rst
>> @@ -79,6 +79,38 @@ MHI client driver performs read operation, same 
>> data gets looped back to MHI
>>   host using LOOPBACK channel 1. LOOPBACK channel is used to verify 
>> data path
>>   and data integrity between MHI Host and MHI device.
> 
> Nice.
[..]
>> +
>> +enum debug_level {
>> +    DBG_LVL_VERBOSE,
>> +    DBG_LVL_INFO,
>> +    DBG_LVL_ERROR,
>> +};
>> +
>> +enum test_status {
>> +    TEST_STATUS_SUCCESS,
>> +    TEST_STATUS_ERROR,
>> +    TEST_STATUS_NO_DEV,
>> +};
>> +
> 
> Since you are running this test as part of kselftest, please use
> ksft errors nd returns.
Are you suggesting to use following macros instead of test_status enum ?
#define KSFT_PASS  0
#define KSFT_FAIL  1

> 
>> +struct lb_test_ctx {
>> +    char dev_node[256];
>> +    unsigned char *tx_buff;
>> +    unsigned char *rx_buff;
>> +    unsigned int rx_pkt_count;
>> +    unsigned int tx_pkt_count;
>> +    int iterations;
>> +    bool iter_complete;
>> +    bool comp_complete;
>> +    bool test_complete;
>> +    bool all_complete;
>> +    unsigned long buff_size;
>> +    long byte_recvd;
>> +    long byte_sent;
>> +};
>> +
>> +bool force_exit;
>> +char write_data = 'a';
>> +int completed_iterations;
>> +
>> +struct lb_test_ctx test_ctxt;
>> +enum debug_level msg_lvl;
>> +struct pollfd read_fd;
>> +struct pollfd write_fd;
>> +enum test_status mhi_test_return_value;
>> +enum test_status tx_status;
>> +enum test_status rx_status;
>> +enum test_status cmp_rxtx_status;
>> +
>> +#define test_log(test_msg_lvl, format, ...) do { \
>> +        if (test_msg_lvl >= msg_lvl) \
>> +            fprintf(stderr, format, ##__VA_ARGS__); \
>> +} while (0)
>> +
>> +static void loopback_test_sleep_ms(int ms)
>> +{
>> +    usleep(1000 * ms);
>> +}
>> +
> 
> Have you run this as part of "make kselftest" run. How does this
> sleep work in that env.?
Looks like kselftest runs this test application by directly executing 
the binary, but this test application requires a valid mhi device file 
node as a required parameter. So considering that requirement, is this 
test application qualifies to run using kselftest ? Without a valid 
device file node test would fail. Is there an option to run this test as 
standalone test which can only be run when a mhi device file node is 
present ? Having said that i tested this driver by
directly executing it using the test binary which is compiled using
make loopback_test under mhi dir.

> Are there any cases where this test can't run and have to - those
> cases need to be skips.
Yes, as this test application can not run by itself it needs a valid mhi 
device file node to write and test reads the same device node to get the 
data back.
So test can not be run without having a MHI device connected over a 
transport (in my testing MHI device is connected over PCIe). Could you 
please suggest an option to use this test application as a standalone 
test instead of being part of kselftest?
> 
> thanks,
> -- Shuah

Thanks,
Hemant
-- 
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