[PATCH v3 13/16] Documentation: accel/thames: Add initial docs

[Tomeu Vizoso]

With pointers to the other components and how users can make use of it.

Assisted-by: LLM
Signed-off-by: Tomeu Vizoso <tomeu at tomeuvizoso.net>
---
 Documentation/accel/index.rst        |  1 +
 Documentation/accel/thames/index.rst | 47 ++++++++++++++++++++++++++++++++++++
 MAINTAINERS                          |  1 +
 3 files changed, 49 insertions(+)

diff --git a/Documentation/accel/index.rst b/Documentation/accel/index.rst
index cbc7d4c3876a..eb115413db07 100644
--- a/Documentation/accel/index.rst
+++ b/Documentation/accel/index.rst
@@ -11,3 +11,4 @@ Compute Accelerators
    amdxdna/index
    qaic/index
    rocket/index
+   thames/index
diff --git a/Documentation/accel/thames/index.rst b/Documentation/accel/thames/index.rst
new file mode 100644
index 000000000000..6382ff2369be
--- /dev/null
+++ b/Documentation/accel/thames/index.rst
@@ -0,0 +1,47 @@
+.. SPDX-License-Identifier: GPL-2.0-only
+
+============================================================
+ accel/thames Driver for the C7x DSPs from Texas Instruments
+============================================================
+
+The accel/thames driver supports the C7x DSP cores of the Texas Instruments
+J722S as compute accelerators, for workloads such as machine learning
+inference.
+
+Each core runs a firmware that remoteproc (Documentation/staging/remoteproc.rst)
+loads;
+the driver attaches to a core remoteproc has booted, boots one left offline, and
+resets a core through it after a fault or a timeout.  The firmware's source is
+at https://gitlab.freedesktop.org/tomeu/thames-firmware/.
+
+The driver and the firmware of a core share a block of memory reserved in the
+device tree.  It holds the core's Ring, the queue of submitted Jobs in the
+order the core runs them, and its Fence, the sequence number the firmware
+writes as each Job completes.  The driver adds an entry to the Ring and rings a
+mailbox doorbell; the firmware rings one back when the Fence moves.
+
+Each file that opens the device gets a Context: a page table the core switches
+to while it runs the Context's Jobs, so the buffers of one client are isolated
+from the others'.  A buffer is created without a mapping and bound into the
+Context at a DSP address the client chooses.
+
+A Job is created once from a program, its parameters and the transfers the
+core's DMA unit performs around it, and is checked then.  It can then be
+submitted any number of times, in arrays of Jobs that run in order and signal
+sync objects when they finish; the call waits on no sync object, the fences of
+the listed buffers order the work.  The drm-gpu-scheduler spreads the
+submissions over the cores.  A Job that faults leaves a fault record, which
+userspace reads with a query; the capability query returns the sizes and
+addresses userspace compiles against.
+
+Everything else is done in userspace, as a Gallium driver (also called thames)
+that is part of the Mesa3D project: https://docs.mesa3d.org/teflon.html
+
+The interface is described in ``include/uapi/drm/thames_accel.h``.
+
+.. kernel-doc:: include/uapi/drm/thames_accel.h
+   :doc: Terms
+
+Hardware currently supported:
+
+* J722S
diff --git a/MAINTAINERS b/MAINTAINERS
index c63ab2d77b01..dce817531184 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -8024,6 +8024,7 @@ M:	Tomeu Vizoso <tomeu at tomeuvizoso.net>
 L:	dri-devel at lists.freedesktop.org
 S:	Supported
 T:	git https://gitlab.freedesktop.org/drm/misc/kernel.git
+F:	Documentation/accel/thames/
 F:	drivers/accel/thames/
 F:	include/uapi/drm/thames_accel.h
 

-- 
2.54.0