linux-kernel - [PATCH RFC 0/3] add VCP mailbox and IPC driver

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Message-ID: <20250305082047.15746-1-jjian.zhou@mediatek.com>
Date: Wed, 5 Mar 2025 16:20:37 +0800
From: Jjian Zhou <jjian.zhou@...iatek.com>
To: Jassi Brar <jassisinghbrar@...il.com>, Rob Herring <robh@...nel.org>,
	Krzysztof Kozlowski <krzk+dt@...nel.org>, Conor Dooley <conor+dt@...nel.org>,
	Matthias Brugger <matthias.bgg@...il.com>, AngeloGioacchino Del Regno
	<angelogioacchino.delregno@...labora.com>
CC: <linux-kernel@...r.kernel.org>, <devicetree@...r.kernel.org>,
	<linux-arm-kernel@...ts.infradead.org>, <linux-mediatek@...ts.infradead.org>,
	<Project_Global_Chrome_Upstream_Group@...iatek.com>, Jason-ch Chen
	<jason-ch.chen@...iatek.com>, Jjian Zhou <jjian.zhou@...iatek.com>
Subject: [PATCH RFC 0/3] add VCP mailbox and IPC driver

The VCP mailbox has 5 groups. Each group has corresponding interrupts,
registers, and 64 slots (each slot is 4 bytes). Since different features
share one of the mailbox groups, the VCP mailbox needs to establish a
send table and a receive table. The send table is used to record the
feature ID, mailbox ID, and the number of slots occupied. The receive table
is used to record the feature ID, mailbox ID, the number of slots occupied,
and the receive options. The API setup_mbox_table in mtk-vcp-ipc.c calculates
the slot offset and pin index for each feature ID based on the mailbox ID and
slot number in the send and receive tables (several slots form a pin, and
each pin can trigger an interrupt). These descriptions are written in the
mtk-vcp-ipc.c file -- we call it the IPC layer.

We have two questions:
How should we describe the mailbox and IPI?
Can the intermediate IPC layer be rewritten as a virtual mailbox layer?

Example of send and recve table:
Operation | mbox_id | ipi_id | msg_size | align_size | slot_ofs | pin_index |  notes
send          0          0       18          18           0          0
recv          0          1       18          18          18          9
send          1         15        8           8           0          0
send          1         16       18          18           8          4
send          1          9        2           2          26         13
recv          1         15        8           8          28         14       ack of send ipi_id=15
recv          1         17       18          18          36         18
recv          1         10        2           2          54         27       ack of send ipi_id=2
send          2         11       18          18           0          0
send          2          2        2           2          18          9
send          2          3        3           4          20         10
send          2         32        2           2          24         12
recv          2         12       18          18          26         13
recv          2          5        1           2          44         22
recv          2          2        1           2          46         23

Recv ipi_id=2 is the ack of send ipi_id=2(The ipi_id=15 is the same.)

Jjian Zhou (3):
  mailbox: mediatek: Add mtk-vcp-mailbox driver
  firmware: mediatek: Add vcp ipc protocol interface
  dt-bindings: mailbox: mtk,vcp-mbox: add mtk vcp-mbox document

 .../bindings/mailbox/mtk,vcp-mbox.yaml        |  49 ++
 drivers/firmware/Kconfig                      |   9 +
 drivers/firmware/Makefile                     |   1 +
 drivers/firmware/mtk-vcp-ipc.c                | 481 ++++++++++++++++++
 drivers/mailbox/Kconfig                       |   9 +
 drivers/mailbox/Makefile                      |   2 +
 drivers/mailbox/mtk-vcp-mailbox.c             | 179 +++++++
 include/linux/firmware/mediatek/mtk-vcp-ipc.h | 151 ++++++
 include/linux/mailbox/mtk-vcp-mailbox.h       |  34 ++
 9 files changed, 915 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/mailbox/mtk,vcp-mbox.yaml
 create mode 100644 drivers/firmware/mtk-vcp-ipc.c
 create mode 100644 drivers/mailbox/mtk-vcp-mailbox.c
 create mode 100644 include/linux/firmware/mediatek/mtk-vcp-ipc.h
 create mode 100644 include/linux/mailbox/mtk-vcp-mailbox.h

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2.45.2