[PATCH v4 0/4] Add APIs to request TX/RX DMA channels for thread ID

[Siddharth Vadapalli <s-vadapalli@ti.com>]

The existing APIs for requesting TX and RX DMA channels rely on parsing
a device-tree node to obtain the Channel/Thread IDs from their names.
However, it is possible to know the thread IDs by alternative means such
as being informed by Firmware on a remote core via RPMsg regarding the
allocated TX/RX DMA channel thread IDs. In such cases, the driver can be
probed by non device-tree methods such as RPMsg-bus, due to which it is not
necessary that the device using the DMA has a device-tree node
corresponding to it. Thus, add APIs to enable the driver to make use of
the existing DMA APIs even when there's no device-tree node.

Additionally, since the name of the device for the remote RX channel is
being set purely on the basis of the RX channel ID itself, it can result
in duplicate names when multiple flows are used on the same channel.
Avoid name duplication by including the flow in the name.

Series is based on linux-next tagged next-20240124.

v3:
https://lore.kernel.org/r/20231218062640.2338453-1-s-vadapalli@ti.com/
Changes since v3:
- Rebased series on linux-next tagged next-20240124.
- Collected Acked-by tag from Peter Ujfalusi <peter.ujfalusi@gmail.com> at:
  https://lore.kernel.org/r/4b5bd2c2-37c9-4cdf-934d-8bc6d6f73152@gmail.com/
  for the series.

v2:
https://lore.kernel.org/r/20231212111011.1401641-1-s-vadapalli@ti.com/
Changes since v2:
- Rebased series on linux-next tagged next-20231215.
- Renamed the function "k3_udma_glue_request_tx_chn_by_id()" to
  "k3_udma_glue_request_tx_chn_for_thread_id()" as suggested by:
  Péter Ujfalusi <peter.ujfalusi@gmail.com>
- Similar to the above change, I have also renamed the function
  "k3_udma_glue_request_remote_rx_chn_by_id()" to
  "k3_udma_glue_request_remote_rx_chn_for_thread_id()".
- Updated the function prototypes in include/linux/dma/k3-udma-glue.h
  accordingly.
- Updated the commit messages for patches 3/4 and 4/4 to match the
  changes made to the function names.

v1:
https://lore.kernel.org/r/20231114083906.3143548-1-s-vadapalli@ti.com/
Changes since v1:
- Rebased series on linux-next tagged next-20231212.
- Updated commit messages with details regarding the use-case for which
  the newly added APIs will be required.
- Removed unnecessary return value check within
  "of_k3_udma_glue_parse_chn()" function in patch 1, since it will fall
  through to "out_put_spec" anyway.
- Removed unnecessary return value check within
  "of_k3_udma_glue_parse_chn_by_id()" function in patch 1, since it will
  fall through to "out_put_spec" anyway.
- Moved patch 4 of v1 series to patch 2 of current series.

RFC Series:
https://lore.kernel.org/r/20231111121555.2656760-1-s-vadapalli@ti.com/
Changes since RFC Series:
- Rebased patches 1, 2 and 3 on linux-next tagged next-20231114.
- Added patch 4 to the series.

Regards,
Siddharth.

Siddharth Vadapalli (4):
  dmaengine: ti: k3-udma-glue: Add function to parse channel by ID
  dmaengine: ti: k3-udma-glue: Update name for remote RX channel device
  dmaengine: ti: k3-udma-glue: Add function to request TX chan for
    thread ID
  dmaengine: ti: k3-udma-glue: Add function to request RX chan for
    thread ID

 drivers/dma/ti/k3-udma-glue.c    | 306 ++++++++++++++++++++++---------
 include/linux/dma/k3-udma-glue.h |  10 +
 2 files changed, 229 insertions(+), 87 deletions(-)

-- 
2.34.1