[PATCH v5 0/2] accel: Add Arm Ethos-U NPU

Rob Herring (Arm)
2025-10-16T21:10:09Z

The Arm Ethos-U65/85 NPUs are designed for edge AI inference
applications[0].

The driver works with Mesa Teflon. The Ethos support was merged on
10/15. The UAPI should also be compatible with the downstream (open
source) driver stack[2] and Vela compiler though that has not been
implemented.

Testing so far has been on i.MX93 boards with Ethos-U65 and a FVP model
with Ethos-U85. More work is needed in mesa for handling U85 command
stream differences, but that doesn't affect the UAPI.

A git tree is here[3].

Rob

[0] https://www.arm.com/products/silicon-ip-cpu?families=ethos%20npus
[2] https://gitlab.arm.com/artificial-intelligence/ethos-u/
[3] git://git.kernel.org/pub/scm/linux/kernel/git/robh/linux.git ethos-v5

Signed-off-by: Rob Herring (Arm) <robh@kernel.org>
---
Changes in v5:
- Rework Runtime PM init in probe
- Use __free() cleanups where possible
- Use devm_mutex_init()
- Handle U85 NPU_SET_WEIGHT2_BASE and NPU_SET_WEIGHT2_LENGTH
- Link to v4: https://lore.kernel.org/r/20251015-ethos-v4-0-81025a3dcbf3@kernel.org

Changes in v4:
- Use bulk clk API
- Various whitespace fixes mostly due to ethos->ethosu rename
- Drop error check on dma_set_mask_and_coherent()
- Drop unnecessary pm_runtime_mark_last_busy() call
- Move variable declarations out of switch (a riscv/clang build failure)
- Use lowercase hex in all defines
- Drop unused ethosu_device.coherent member
- Add comments on all locks
- Link to v3: https://lore.kernel.org/r/20250926-ethos-v3-0-6bd24373e4f5@kernel.org

Changes in v3:
- Rework and improve job submit validation
- Rename ethos to ethosu. There was an Ethos-Nxx that's unrelated.
- Add missing init for sched_lock mutex
- Drop some prints to debug level
- Fix i.MX93 SRAM accesses (AXI config)
- Add U85 AXI configuration and test on FVP with U85
- Print the current cmd value on timeout
- Link to v2: https://lore.kernel.org/r/20250811-ethos-v2-0-a219fc52a95b@kernel.org

Changes in v2:
- Rebase on v6.17-rc1 adapting to scheduler changes
- scheduler: Drop the reset workqueue. According to the scheduler docs,
we don't need it since we have a single h/w queue.
- scheduler: Rework the timeout handling to continue running if we are
making progress. Fixes timeouts on larger jobs.
- Reset the NPU on resume so it's in a known state
- Add error handling on clk_get() calls
- Fix drm_mm splat on module unload. We were missing a put on the
cmdstream BO in the scheduler clean-up.
- Fix 0-day report needing explicit bitfield.h include
- Link to v1: https://lore.kernel.org/r/20250722-ethos-v1-0-cc1c5a0cbbfb@kernel.org

---
Rob Herring (Arm) (2):
dt-bindings: npu: Add Arm Ethos-U65/U85
accel: Add Arm Ethos-U NPU driver

.../devicetree/bindings/npu/arm,ethos.yaml | 79 +++
MAINTAINERS | 9 +
drivers/accel/Kconfig | 1 +
drivers/accel/Makefile | 1 +
drivers/accel/ethosu/Kconfig | 10 +
drivers/accel/ethosu/Makefile | 4 +
drivers/accel/ethosu/ethosu_device.h | 195 ++++++
drivers/accel/ethosu/ethosu_drv.c | 403 ++++++++++++
drivers/accel/ethosu/ethosu_drv.h | 15 +
drivers/accel/ethosu/ethosu_gem.c | 704 +++++++++++++++++++++
drivers/accel/ethosu/ethosu_gem.h | 46 ++
drivers/accel/ethosu/ethosu_job.c | 540 ++++++++++++++++
drivers/accel/ethosu/ethosu_job.h | 41 ++
include/uapi/drm/ethosu_accel.h | 261 ++++++++
14 files changed, 2309 insertions(+)
---
base-commit: 3a8660878839faadb4f1a6dd72c3179c1df56787
change-id: 20250715-ethos-3fdd39ef6f19

Best regards,
--
Rob Herring (Arm) <robh@kernel.org>