Linux kernel stable tree (mirror) https://git.radix-linux.su/kernel/linux.git/atom?h=v5.4.225 2019-08-12T13:19:25+00:00 2019-08-12T13:19:25+00:00 Daniel Baluta daniel.baluta@nxp.com 2019-08-01T09:56:36+00:00 urn:sha1:ffbf23d50353915dc2622a3b7b4ddc678165f92d Some of i.MX8 processors (e.g i.MX8QM, i.MX8QXP) contain the Tensilica HiFi4 DSP for advanced pre- and post-audio processing. The communication between Host CPU and DSP firmware is taking place using a shared memory area for message passing and a dedicated Messaging Unit for notifications. DSP IPC protocol offers a doorbell interface using imx-mailbox API. We use 4 MU channels (2 x TXDB, 2 x RXDB) to implement a request-reply protocol. Connection 0 (txdb0, rxdb0): - Host writes messasge to shared memory [SHMEM] - Host sends a request [MU] - DSP handles request [SHMEM] - DSP sends reply [MU] Connection 1 (txdb1, rxdb1): - DSP writes a message to shared memory [SHMEM] - DSP sends a request [MU] - Host handles request [SHMEM] - Host sends reply [MU] The protocol interface will be used by a Host client to communicate with the DSP. First client will be the i.MX8 part from Sound Open Firmware infrastructure. The protocol offers the following interface: On Tx: - imx_dsp_ring_doorbell, will be called to notify the DSP that it needs to handle a request. On Rx: - clients need to provide two callbacks: .handle_reply .handle_request - the callbacks will be used by the protocol on notification arrival from DSP. Signed-off-by: Daniel Baluta <daniel.baluta@nxp.com> Reviewed-by: Oleksij Rempel <o.rempel@pengutronix.de> Signed-off-by: Shawn Guo <shawnguo@kernel.org>