[PATCH v2 0/6] Add AMD PL Mailbox and RPMsg support for the AMD BRAM remoteproc

[Ben Levinsky <ben.levinsky@amd.com>]

This series adds a mailbox controller for the AMD programmable-logic (PL)
Mailbox soft IP and uses it to add RPMsg support to the AMD MicroBlaze/V
BRAM remoteproc driver, so that a soft processor in the PL can communicate
with Linux over virtio-rpmsg.

Patches 1-2 fix the existing BRAM remoteproc driver:
- Pass the device name to rproc_mem_entry_init() through a constant format
  string instead of using it as the format.
- Drive the reset GPIO with gpiod_direction_output() so a start still
  produces a reset pulse after the PL has been reconfigured, which restores
  the AXI GPIO to its default direction.

Patches 3-4 add the binding and the mailbox-framework controller for the
PL Mailbox IP. The controller exposes independent TX and RX channels. Its
interface clock is enabled only while a channel is started. RX uses a
threaded receive-threshold interrupt that drains the FIFO, with the FIFO
depth taken from the device tree. TX completion is reported by
mailbox-core polling of the send-threshold status bit.

Patches 5-6 extend the BRAM remoteproc binding and driver with optional
mailbox channels and named reserved-memory regions for the vrings and the
shared RPMsg buffer pool. The driver registers the carveouts, exposes the
loaded resource table, requests the mailbox channels at probe time, sends
virtqueue notification IDs through the mailbox framework, and defers
received notifications to process context. Without mailboxes the driver
keeps supporting load, start and stop only.

The series is based on mainline during the v7.4 merge window and uses the
remoteproc wc-ioremap and optional resource-table helpers merged for
v7.3-rc1.

Changes in v2:
- dt-bindings: mailbox:
  - Use the single compatible "amd,pl-mailbox-2.1". The Mailbox is a soft
    IP core in programmable logic, not a SoC block, so like other PL soft
    IP bindings the compatible names the IP core and its version instead
    of a SoC. "pl" distinguishes it from the IPI mailbox hardware.
  - Rename amd,mbox-pl-fifo-len to amd,pl-mailbox-depth, and explain that
    the depth is chosen per IP instance at synthesis time and cannot be
    read from the registers.
  - Add the MAINTAINERS entry together with the binding.
- mailbox:
  - Match only amd,pl-mailbox-2.1.
  - Depend on ARCH_ZYNQMP || COMPILE_TEST.
  - Do not access the FIFO when the mailbox core submits a queued message
    after the transmit channel has started to shut down.
  - Handle the receive interrupt in a threaded handler that acknowledges
    the event first and then drains the FIFO until it is empty, so a full
    FIFO can no longer stall reception.
  - Add a file header with the driver description and copyright.
- dt-bindings: remoteproc: drop the redundant dependentRequired block.
- remoteproc:
  - Keep the existing dependencies and add "depends on MAILBOX" instead
    of selecting user-visible symbols. Name the PL Mailbox controller and
    the virtio RPMsg bus in the help text.
  - Request the mailbox channels at probe time, so a missing controller
    defers the probe, and release them on unbind.
  - Free the mailbox channels before cancelling the receive work, so a
    late notification cannot queue it again.

v1: https://lore.kernel.org/r/20261014213426.2957480-1-ben.levinsky@amd.com

Ben Levinsky (6):
  remoteproc: amd_mbv_bram: Bound device name formatting
  remoteproc: amd_mbv_bram: Restore reset GPIO direction after PL
    reconfig
  dt-bindings: mailbox: Add AMD PL Mailbox IP
  mailbox: Add AMD PL Mailbox soft IP controller
  dt-bindings: remoteproc: Add RPMsg resources to AMD BRAM rproc
  remoteproc: amd_mbv_bram: Add RPMsg support

 .../bindings/mailbox/amd,pl-mailbox-2.1.yaml  |  73 ++++
 .../bindings/remoteproc/amd,bram-rproc.yaml   |  21 +
 MAINTAINERS                                   |   7 +
 drivers/mailbox/Kconfig                       |  11 +
 drivers/mailbox/Makefile                      |   1 +
 drivers/mailbox/amd-pl-mailbox.c              | 378 ++++++++++++++++++
 drivers/remoteproc/Kconfig                    |   5 +
 drivers/remoteproc/amd_mbv_bram_rproc.c       | 270 ++++++++++++-
 8 files changed, 761 insertions(+), 5 deletions(-)
 create mode 100644 Documentation/devicetree/bindings/mailbox/amd,pl-mailbox-2.1.yaml
 create mode 100644 drivers/mailbox/amd-pl-mailbox.c


base-commit: 6b4b543fa18757297ac756a6fe6e64f506b7844a
-- 
2.34.1