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. Patch is tested using arm64 based platform.
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 (4):
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
Documentation/mhi/index.rst | 1 +
Documentation/mhi/uci.rst | 83 +++++
drivers/bus/mhi/Kconfig | 13 +
drivers/bus/mhi/Makefile | 4 +
drivers/bus/mhi/core/internal.h | 1 -
drivers/bus/mhi/core/main.c | 12 +
drivers/bus/mhi/uci.c | 658 ++++++++++++++++++++++++++++++++++++++++
include/linux/mhi.h | 12 +
8 files changed, 783 insertions(+), 1 deletion(-)
create mode 100644 Documentation/mhi/uci.rst
create mode 100644 drivers/bus/mhi/uci.c
--
The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum,
a Linux Foundation Collaborative Project
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 <[email protected]>
Reviewed-by: Jeffrey Hugo <[email protected]>
Reviewed-by: Manivannan Sadhasivam <[email protected]>
---
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 2cff5dd..3950792 100644
--- a/drivers/bus/mhi/core/main.c
+++ b/drivers/bus/mhi/core/main.c
@@ -258,6 +258,18 @@ 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 d4841e5..7829b1d 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
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 <[email protected]>
---
Documentation/mhi/index.rst | 1 +
Documentation/mhi/uci.rst | 83 +++++++++++++++++++++++++++++++++++++++++++++
2 files changed, 84 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..fe901c4
--- /dev/null
+++ b/Documentation/mhi/uci.rst
@@ -0,0 +1,83 @@
+.. 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.
+
+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, TRE buffer is copied to
+pending list. Reader is unblocked and data is copied to userspace buffer. TRE
+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. MHI channels
+move to disabled state upon driver remove.
+
+release
+-------
+
+Decrements UCI device reference count and UCI channel reference count upon last
+release(). UCI channel clean up is performed. MHI channel moves to disabled
+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 TREs to transfer ring of LOOPBACK channel 1 gets queued and channel
+doorbell is rung. When userspace MHI client performs write operation on device node,
+data buffer gets queued as a TRE 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 diag 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
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 <[email protected]>
---
drivers/bus/mhi/Kconfig | 13 +
drivers/bus/mhi/Makefile | 4 +
drivers/bus/mhi/uci.c | 658 +++++++++++++++++++++++++++++++++++++++++++++++
3 files changed, 675 insertions(+)
create mode 100644 drivers/bus/mhi/uci.c
diff --git a/drivers/bus/mhi/Kconfig b/drivers/bus/mhi/Kconfig
index e841c10..476cc55 100644
--- a/drivers/bus/mhi/Kconfig
+++ b/drivers/bus/mhi/Kconfig
@@ -20,3 +20,16 @@ config MHI_BUS_DEBUG
Enable debugfs support for use with the MHI transport. Allows
reading and/or modifying some values within the MHI controller
for debug and test purposes.
+
+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, 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 19e6443..80feefb 100644
--- a/drivers/bus/mhi/Makefile
+++ b/drivers/bus/mhi/Makefile
@@ -1,2 +1,6 @@
# core layer
obj-y += core/
+
+# 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..6c64356
--- /dev/null
+++ b/drivers/bus/mhi/uci.c
@@ -0,0 +1,658 @@
+// 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 DEVICE_NAME "mhi"
+#define MHI_UCI_DRIVER_NAME "mhi_uci"
+#define 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_trbs, i, ret = -EIO;
+ size_t dl_buf_size;
+ void *buf;
+ struct uci_buf *ubuf;
+
+ /* dont queue if dl channel is not supported */
+ if (!udev->mhi_dev->dl_chan)
+ return 0;
+
+ nr_trbs = mhi_get_free_desc_count(mhi_dev, DMA_FROM_DEVICE);
+
+ for (i = 0; i < nr_trbs; 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_trbs,
+ 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) {
+ dev_dbg(dev, "Client can read from node\n");
+ mask |= EPOLLIN | EPOLLRDNORM;
+ }
+ spin_unlock_bh(&uchan->dl_pending_lock);
+
+ if (mhi_get_free_desc_count(mhi_dev, DMA_TO_DEVICE) > 0) {
+ dev_dbg(dev, "Client can write to node\n");
+ 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_avail = 0;
+
+ /* if ul channel is not supported return error */
+ if (!buf || !count || !mhi_dev->ul_chan)
+ return -EINVAL;
+
+ dev_dbg(dev, "%s: to xfer: %zu bytes\n", __func__, count);
+
+ mutex_lock(&uchan->write_lock);
+ 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_avail = 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_avail > 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 (!buf || !mhi_dev->dl_chan)
+ return -EINVAL;
+
+ mutex_lock(&uchan->read_lock);
+ 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, "status: %d xfer_len: %zu\n",
+ 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, "status: %d receive_len: %zu\n",
+ 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, 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,
+ 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
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 <[email protected]>
Reviewed-by: Jeffrey Hugo <[email protected]>
Reviewed-by: Manivannan Sadhasivam <[email protected]>
---
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 7989269..4abf0cf 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 7829b1d..6e1122c 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
On Fri, 23 Oct 2020 16:17:54 -0700 Hemant Kumar wrote:
> +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.
What's the user space that talks to this?
On Mon, 2020-10-26 at 07:38 -0600, Jeffrey Hugo wrote:
> On 10/25/2020 3:46 PM, Jakub Kicinski wrote:
> > On Fri, 23 Oct 2020 16:17:54 -0700 Hemant Kumar wrote:
> > > +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.
> >
> > What's the user space that talks to this?
> >
>
> Multiple.
>
> Each channel has a different purpose. There it is expected that a
> different userspace application would be using it.
>
> Hemant implemented the loopback channel, which is a simple channel
> that
> just sends you back anything you send it. Typically this is consumed
> by
> a test application.
>
> Diag is a typical channel to be consumed by userspace. This is
> consumed
> by various applications that talk to the remote device for
> diagnostic
> information (logs and such).
QMI too?
Dan
> Sahara is another common channel that is usually used for the
> multistage
> firmware loading process.
>
On 10/26/2020 7:46 AM, Dan Williams wrote:
> On Mon, 2020-10-26 at 07:38 -0600, Jeffrey Hugo wrote:
>> On 10/25/2020 3:46 PM, Jakub Kicinski wrote:
>>> On Fri, 23 Oct 2020 16:17:54 -0700 Hemant Kumar wrote:
>>>> +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.
>>>
>>> What's the user space that talks to this?
>>>
>>
>> Multiple.
>>
>> Each channel has a different purpose. There it is expected that a
>> different userspace application would be using it.
>>
>> Hemant implemented the loopback channel, which is a simple channel
>> that
>> just sends you back anything you send it. Typically this is consumed
>> by
>> a test application.
>>
>> Diag is a typical channel to be consumed by userspace. This is
>> consumed
>> by various applications that talk to the remote device for
>> diagnostic
>> information (logs and such).
>
> QMI too?
> Dan
Interesting question. My product doesn't use QMI. I would expect that
all QMI runs through Router these days, but I am seeing some QMI
channels in the downstream source.
Hemant, Do you know what is the usecase for the QMI0/QMI1 channels?
--
Jeffrey Hugo
Qualcomm Technologies, Inc. is a member of the
Code Aurora Forum, a Linux Foundation Collaborative Project.
On 10/25/2020 3:46 PM, Jakub Kicinski wrote:
> On Fri, 23 Oct 2020 16:17:54 -0700 Hemant Kumar wrote:
>> +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.
>
> What's the user space that talks to this?
>
Multiple.
Each channel has a different purpose. There it is expected that a
different userspace application would be using it.
Hemant implemented the loopback channel, which is a simple channel that
just sends you back anything you send it. Typically this is consumed by
a test application.
Diag is a typical channel to be consumed by userspace. This is consumed
by various applications that talk to the remote device for diagnostic
information (logs and such).
Sahara is another common channel that is usually used for the multistage
firmware loading process.
--
Jeffrey Hugo
Qualcomm Technologies, Inc. is a member of the
Code Aurora Forum, a Linux Foundation Collaborative Project.
On 10/26/20 6:56 AM, Jeffrey Hugo wrote:
> On 10/26/2020 7:46 AM, Dan Williams wrote:
>> On Mon, 2020-10-26 at 07:38 -0600, Jeffrey Hugo wrote:
>>> On 10/25/2020 3:46 PM, Jakub Kicinski wrote:
>>>> On Fri, 23 Oct 2020 16:17:54 -0700 Hemant Kumar wrote:
>>>>> +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.
>>>>
>>>> What's the user space that talks to this?
>>>>
>>>
>>> Multiple.
>>>
>>> Each channel has a different purpose. There it is expected that a
>>> different userspace application would be using it.
>>>
>>> Hemant implemented the loopback channel, which is a simple channel
>>> that
>>> just sends you back anything you send it. Typically this is consumed
>>> by
>>> a test application.
>>>
>>> Diag is a typical channel to be consumed by userspace. This is
>>> consumed
>>> by various applications that talk to the remote device for
>>> diagnostic
>>> information (logs and such).
>>
>> QMI too?
>> Dan
>
> Interesting question. My product doesn't use QMI. I would expect that
> all QMI runs through Router these days, but I am seeing some QMI
> channels in the downstream source.
>
> Hemant, Do you know what is the usecase for the QMI0/QMI1 channels?
>
QMI0/QMI1 is used to send QMI message (control path) to bring the qmi
rmnet data call.
Thanks,
Hemant
--
The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum,
a Linux Foundation Collaborative Project
On Mon, 26 Oct 2020 07:38:46 -0600 Jeffrey Hugo wrote:
> On 10/25/2020 3:46 PM, Jakub Kicinski wrote:
> > On Fri, 23 Oct 2020 16:17:54 -0700 Hemant Kumar wrote:
> >> +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.
> >
> > What's the user space that talks to this?
>
> Multiple.
>
> Each channel has a different purpose. There it is expected that a
> different userspace application would be using it.
>
> Hemant implemented the loopback channel, which is a simple channel that
> just sends you back anything you send it. Typically this is consumed by
> a test application.
>
> Diag is a typical channel to be consumed by userspace. This is consumed
> by various applications that talk to the remote device for diagnostic
> information (logs and such).
>
> Sahara is another common channel that is usually used for the multistage
> firmware loading process.
Thanks for the info, are there any open source tests based on the
loopback channel (perhaps even in tree?)
Since that's the only channel enabled in this set its the only one
we can comment on.
Hi Jakub,
On 10/26/20 3:56 PM, Jakub Kicinski wrote:
> On Mon, 26 Oct 2020 07:38:46 -0600 Jeffrey Hugo wrote:
>> On 10/25/2020 3:46 PM, Jakub Kicinski wrote:
>>> On Fri, 23 Oct 2020 16:17:54 -0700 Hemant Kumar wrote:
>>>> +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.
>>>
>>> What's the user space that talks to this?
>>
>> Multiple.
>>
>> Each channel has a different purpose. There it is expected that a
>> different userspace application would be using it.
>>
>> Hemant implemented the loopback channel, which is a simple channel that
>> just sends you back anything you send it. Typically this is consumed by
>> a test application.
>>
>> Diag is a typical channel to be consumed by userspace. This is consumed
>> by various applications that talk to the remote device for diagnostic
>> information (logs and such).
>>
>> Sahara is another common channel that is usually used for the multistage
>> firmware loading process.
>
> Thanks for the info, are there any open source tests based on the
> loopback channel (perhaps even in tree?)
>
> Since that's the only channel enabled in this set its the only one
> we can comment on.
>
i am not aware of any open source tests based on loopback channel. My
testing includes multiple sessions of echo, cat etc using adb to confirm
what is sent is received back. Loic is using UCI driver for his use case
too.
Loic, in case you have any use case (which is part of open source) which
can use UCI driver, pls share that info ?
I think as soon as UCI becomes part of the tree, more and more channels
would get added to the driver having open source code for that from
other folks in community (Loic would be one of them i guess).
Thanks,
Hemant
--
The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum,
a Linux Foundation Collaborative Project
Hi Loic,
On 10/26/20 10:34 AM, Loic Poulain wrote:
> Hi Hemant,
>
> That looks better IMHO, just small comments on locking.
>
[..]
> +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_avail = 0;
> +
> + /* if ul channel is not supported return error */
> + if (!buf || !count || !mhi_dev->ul_chan)
> + return -EINVAL;
> +
> + dev_dbg(dev, "%s: to xfer: %zu bytes\n", __func__, count);
> +
> + mutex_lock(&uchan->write_lock);
>
>
> Maybe mutex_lock_interruptible is more appropriate here (same in read fops).
i agree, will return -EINTR if mutex_lock_interruptible returns < 0.
>
[..]
> +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 (!buf || !mhi_dev->dl_chan)
> + return -EINVAL;
> +
> + mutex_lock(&uchan->read_lock);
> + 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 you need to protect dl_pending list against concurent access, you
> need to do it in wait_event as well. I would suggest to lookg at
> `wait_event_interruptible_lock_irq` function, that allows to pass a
> locked spinlock as parameter. That would be safer and prevent this
> lock/unlock dance.
When using this API difference is, first we take spin_lock_bh() and then
wait API is using spin_unlock_irq()/spin_lock_irq(). I am getting
"BUG: scheduling while atomic" when i use this way. When i changed
spin_lock_bh to spin_lock_irq then we got rid of the kernel BUG.
Thanks,
Hemant
--
The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum,
a Linux Foundation Collaborative Project