Hi Greg, On Wed, Jan 06, 2021 at 10:44:13AM -0800, Hemant Kumar wrote: > This patch series adds support for UCI driver. UCI driver enables userspace > clients to communicate to external MHI devices like modem. 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. > > This interface allows exposing modem control channel(s) such as QMI, MBIM, > or AT commands to userspace which can be used to configure the modem using > tools such as libqmi, ModemManager, minicom (for AT), etc over MHI. This is > required as there are no kernel APIs to access modem control path for device > configuration. Data path transporting the network payload (IP), however, is > routed to the Linux network via the mhi-net driver. Currently driver supports > QMI channel. libqmi is userspace MHI client which communicates to a QMI > service using QMI channel. Please refer to > https://www.freedesktop.org/wiki/Software/libqmi/ for additional information > on libqmi. > > Patch is tested using arm64 and x86 based platform. > This series looks good to me and I'd like to merge it into mhi-next. You shared your reviews on the previous revisions, so I'd like to get your opinion first. Thanks, Mani > V18: > - Updated commit text for UCI to clarify why this driver is required for QMI > over MHI. Also updated cover letter with same information. > > v17: > - Updated commit text for UCI driver by mentioning about libqmi open-source > userspace program that will be talking to this UCI kernel driver. > - UCI driver depends upon patch "bus: mhi: core: Add helper API to return number > of free TREs". > > v16: > - Removed reference of WLAN as an external MHI device in documentation and > cover letter. > > v15: > - Updated documentation related to poll and release operations. > > V14: > - Fixed device file node format to /dev/<mhi_dev_name> instead of > /dev/mhi_<mhi_dev_name> because "mhi" is already part of mhi device name. > For example old format: /dev/mhi_mhi0_QMI new format: /dev/mhi0_QMI. > - Updated MHI documentation to reflect index mhi controller name in > QMI usage example. > > V13: > - Removed LOOPBACK channel from mhi_device_id table from this patch series. > Pushing a new patch series to add support for LOOPBACK channel and the user > space test application. Also removed the description from kernel documentation. > - Added QMI channel to mhi_device_id table. QMI channel has existing libqmi > support from user space. > - Updated kernel Documentation for QMI channel and provided external reference > for libqmi. > - Updated device file node name by appending mhi device name only, which already > includes mhi controller device name. > > 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 (3): > 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 | 95 ++++++ > drivers/bus/mhi/Kconfig | 13 + > drivers/bus/mhi/Makefile | 3 + > drivers/bus/mhi/core/internal.h | 1 - > drivers/bus/mhi/uci.c | 664 ++++++++++++++++++++++++++++++++++++++++ > include/linux/mhi.h | 3 + > 7 files changed, 779 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 >
