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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>
67 lines
1.2 KiB
C
67 lines
1.2 KiB
C
/* SPDX-License-Identifier: GPL-2.0+ */
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/*
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* Copyright 2019 NXP
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*
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* Header file for the DSP IPC implementation
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*/
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#ifndef _IMX_DSP_IPC_H
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#define _IMX_DSP_IPC_H
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#include <linux/device.h>
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#include <linux/types.h>
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#include <linux/mailbox_client.h>
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#define DSP_MU_CHAN_NUM 4
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struct imx_dsp_chan {
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struct imx_dsp_ipc *ipc;
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struct mbox_client cl;
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struct mbox_chan *ch;
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char *name;
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int idx;
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};
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struct imx_dsp_ops {
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void (*handle_reply)(struct imx_dsp_ipc *ipc);
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void (*handle_request)(struct imx_dsp_ipc *ipc);
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};
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struct imx_dsp_ipc {
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/* Host <-> DSP communication uses 2 txdb and 2 rxdb channels */
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struct imx_dsp_chan chans[DSP_MU_CHAN_NUM];
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struct device *dev;
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struct imx_dsp_ops *ops;
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void *private_data;
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};
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static inline void imx_dsp_set_data(struct imx_dsp_ipc *ipc, void *data)
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{
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if (!ipc)
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return;
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ipc->private_data = data;
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}
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static inline void *imx_dsp_get_data(struct imx_dsp_ipc *ipc)
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{
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if (!ipc)
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return NULL;
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return ipc->private_data;
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}
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#if IS_ENABLED(CONFIG_IMX_DSP)
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int imx_dsp_ring_doorbell(struct imx_dsp_ipc *dsp, unsigned int chan_idx);
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#else
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static inline int imx_dsp_ring_doorbell(struct imx_dsp_ipc *ipc,
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unsigned int chan_idx)
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{
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return -ENOTSUPP;
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}
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#endif
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#endif /* _IMX_DSP_IPC_H */
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