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,mt8196-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,mt8196-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 -- 2.45.2
