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. Patch is tested using arm64 and x86 based
platform.
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 (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 | 95 ++++++
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 | 664 ++++++++++++++++++++++++++++++++++++++++
include/linux/mhi.h | 12 +
8 files changed, 800 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
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 6f80ec3..2b9c063 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 e36d575..f072605 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
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 702c31b..74a25e7 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 aa9757e..e36d575 100644
--- a/include/linux/mhi.h
+++ b/include/linux/mhi.h
@@ -599,6 +599,15 @@ 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