Re: [PATCH v2 1/3] dt-bindings: accel: add device tree for AMD PKI accelerator

[Jeff Hugo]

On 4/9/2025 11:30 AM, Nipun Gupta wrote:

No cover letter?

> Add binding documentation for AMD PKI accelerator supported for AMD
> versal-net SoC.
>
> AMD PKI accelerator is a device on AMD versa-net SoC to execute public key
> asymmetric crypto operations like ECDSA, ECDH, RSA etc. with high performance.
> The driver provides accel interface to applications for configuring the device
> and performing the required operations. AMD PKI device comprises of multiple
> Barco Silex ba414 PKI engines bundled together, and providing a queue based
> interface to interact with the device.
>
>   +------------------+
>   |    Software      |
>   +------------------+
>       |          |
>       |          v
>       |     +-----------------------------------------------------------+
>       |     |                     RAM                                   |
>       |     |  +----------------------------+   +---------------------+ |
>       |     |  |           RQ pages         |   |       CQ pages      | |
>       |     |  | +------------------------+ |   | +-----------------+ | |
>       |     |  | |   START (cmd)          | |   | | req_id | status | | |
>       |     |  | |   TFRI (addr, sz)---+  | |   | | req_id | status | | |
>       |     |  | | +-TFRO (addr, sz)   |  | |   | | ...             | | |
>       |     |  | | | NTFY (req_id)     |  | |   | +-----------------+ | |
>       |     |  | +-|-------------------|--+ |   |                     | |
>       |     |  |   |                   v    |   +---------------------+ |
>       |     |  |   |         +-----------+  |                           |
>       |     |  |   |         | input     |  |                           |
>       |     |  |   |         | data      |  |                           |
>       |     |  |   v         +-----------+  |                           |
>       |     |  |  +----------------+        |                           |
>       |     |  |  |  output data   |        |                           |
>       |     |  |  +----------------+        |                           |
>       |     |  +----------------------------+                           |
>       |     |                                                           |
>       |     +-----------------------------------------------------------+
>       |
>       |
>   +---|----------------------------------------------------+
>   |   v                AMD PKI device                      |
>   |  +-------------------+     +------------------------+  |
>   |  | New request FIFO  | --> |       PK engines       |  |
>   |  +-------------------+     +------------------------+  |
>   +--------------------------------------------------------+
>
> To perform a crypto operation, the software writes a sequence of descriptors,
> into the RQ memory. This includes input data and designated location for the
> output data. After preparing the request, request offset (from the RQ memory
> region) is written into the NEW_REQUEST register. Request is then stored in a
> common hardware FIFO shared among all RQs.
>
> When a PK engine becomes available, device pops the request from the FIFO and
> fetches the descriptors. It DMAs the input data from RQ memory and executes
> the necessary computations. After computation is complete, the device writes
> output data back to RAM via DMA. Device then writes a new entry in CQ ring
> buffer in RAM, indicating completion of the request. Device also generates
> an interrupt for notifying completion to the software.
>
> Signed-off-by: Nipun Gupta <nipun.gupta@xxxxxxx>
> ---
>
> The patch series was originally submitted as misc driver:
> https://lore.kernel.org/all/20250312095421.1839220-1-nipun.gupta@xxxxxxx/
>
> As suggested by Greg, the driver does not fit in misc and should be part
> of accel or crypto. Accel is well suited for AMD PKI Crypto Accelerator,
> and thus the driver is updated as an accel driver and yaml moved to
> newly created accel folder.

Why does this not fit in crypto?