Commit ffbf23d5 authored by Daniel Baluta's avatar Daniel Baluta Committed by Shawn Guo
Browse files

firmware: imx: Add DSP IPC protocol interface 



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: default avatarDaniel Baluta <daniel.baluta@nxp.com>
Reviewed-by: default avatarOleksij Rempel <o.rempel@pengutronix.de>
Signed-off-by: default avatarShawn Guo <shawnguo@kernel.org>
parent 73feb4d0

drivers/firmware/imx/Kconfig

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# SPDX-License-Identifier: GPL-2.0-only

config IMX_DSP

	bool "IMX DSP Protocol driver"

	depends on IMX_MBOX

	help

	  This enables DSP IPC protocol between host AP (Linux)

	  and the firmware running on DSP.

	  DSP exists on some i.MX8 processors (e.g i.MX8QM, i.MX8QXP).



	  It acts like a doorbell. Client might use shared memory to

	  exchange information with DSP side.



config IMX_SCU

	bool "IMX SCU Protocol driver"

	depends on IMX_MBOX

drivers/firmware/imx/Makefile

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# SPDX-License-Identifier: GPL-2.0

obj-$(CONFIG_IMX_DSP)		+= imx-dsp.o

obj-$(CONFIG_IMX_SCU)		+= imx-scu.o misc.o imx-scu-irq.o

obj-$(CONFIG_IMX_SCU_PD)	+= scu-pd.o

drivers/firmware/imx/imx-dsp.c

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// SPDX-License-Identifier: GPL-2.0+

/*

 * Copyright 2019 NXP

 *  Author: Daniel Baluta <daniel.baluta@nxp.com>

 *

 * Implementation of the DSP IPC interface (host side)

 */



#include <linux/firmware/imx/dsp.h>

#include <linux/kernel.h>

#include <linux/mailbox_client.h>

#include <linux/module.h>

#include <linux/of_platform.h>

#include <linux/platform_device.h>

#include <linux/slab.h>



/*

 * imx_dsp_ring_doorbell - triggers an interrupt on the other side (DSP)

 *

 * @dsp: DSP IPC handle

 * @chan_idx: index of the channel where to trigger the interrupt

 *

 * Returns non-negative value for success, negative value for error

 */

int imx_dsp_ring_doorbell(struct imx_dsp_ipc *ipc, unsigned int idx)

{

	int ret;

	struct imx_dsp_chan *dsp_chan;



	if (idx >= DSP_MU_CHAN_NUM)

		return -EINVAL;



	dsp_chan = &ipc->chans[idx];

	ret = mbox_send_message(dsp_chan->ch, NULL);

	if (ret < 0)

		return ret;



	return 0;

}

EXPORT_SYMBOL(imx_dsp_ring_doorbell);



/*

 * imx_dsp_handle_rx - rx callback used by imx mailbox

 *

 * @c: mbox client

 * @msg: message received

 *

 * Users of DSP IPC will need to privde handle_reply and handle_request

 * callbacks.

 */

static void imx_dsp_handle_rx(struct mbox_client *c, void *msg)

{

	struct imx_dsp_chan *chan = container_of(c, struct imx_dsp_chan, cl);



	if (chan->idx == 0) {

		chan->ipc->ops->handle_reply(chan->ipc);

	} else {

		chan->ipc->ops->handle_request(chan->ipc);

		imx_dsp_ring_doorbell(chan->ipc, 1);

	}

}



static int imx_dsp_probe(struct platform_device *pdev)

{

	struct device *dev = &pdev->dev;

	struct imx_dsp_ipc *dsp_ipc;

	struct imx_dsp_chan *dsp_chan;

	struct mbox_client *cl;

	char *chan_name;

	int ret;

	int i, j;



	device_set_of_node_from_dev(&pdev->dev, pdev->dev.parent);



	dsp_ipc = devm_kzalloc(dev, sizeof(*dsp_ipc), GFP_KERNEL);

	if (!dsp_ipc)

		return -ENOMEM;



	for (i = 0; i < DSP_MU_CHAN_NUM; i++) {

		if (i < 2)

			chan_name = kasprintf(GFP_KERNEL, "txdb%d", i);

		else

			chan_name = kasprintf(GFP_KERNEL, "rxdb%d", i - 2);



		if (!chan_name)

			return -ENOMEM;



		dsp_chan = &dsp_ipc->chans[i];

		cl = &dsp_chan->cl;

		cl->dev = dev;

		cl->tx_block = false;

		cl->knows_txdone = true;

		cl->rx_callback = imx_dsp_handle_rx;



		dsp_chan->ipc = dsp_ipc;

		dsp_chan->idx = i % 2;

		dsp_chan->ch = mbox_request_channel_byname(cl, chan_name);

		if (IS_ERR(dsp_chan->ch)) {

			ret = PTR_ERR(dsp_chan->ch);

			if (ret != -EPROBE_DEFER)

				dev_err(dev, "Failed to request mbox chan %s ret %d\n",

					chan_name, ret);

			goto out;

		}



		dev_dbg(dev, "request mbox chan %s\n", chan_name);

		/* chan_name is not used anymore by framework */

		kfree(chan_name);

	}



	dsp_ipc->dev = dev;



	dev_set_drvdata(dev, dsp_ipc);



	dev_info(dev, "NXP i.MX DSP IPC initialized\n");



	return devm_of_platform_populate(dev);

out:

	kfree(chan_name);

	for (j = 0; j < i; j++) {

		dsp_chan = &dsp_ipc->chans[j];

		mbox_free_channel(dsp_chan->ch);

	}



	return ret;

}



static int imx_dsp_remove(struct platform_device *pdev)

{

	struct imx_dsp_chan *dsp_chan;

	struct imx_dsp_ipc *dsp_ipc;

	int i;



	dsp_ipc = dev_get_drvdata(&pdev->dev);



	for (i = 0; i < DSP_MU_CHAN_NUM; i++) {

		dsp_chan = &dsp_ipc->chans[i];

		mbox_free_channel(dsp_chan->ch);

	}



	return 0;

}



static struct platform_driver imx_dsp_driver = {

	.driver = {

		.name = "imx-dsp",

	},

	.probe = imx_dsp_probe,

	.remove = imx_dsp_remove,

};

builtin_platform_driver(imx_dsp_driver);



MODULE_AUTHOR("Daniel Baluta <daniel.baluta@nxp.com>");

MODULE_DESCRIPTION("IMX DSP IPC protocol driver");

MODULE_LICENSE("GPL v2");

include/linux/firmware/imx/dsp.h

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/* SPDX-License-Identifier: GPL-2.0+ */

/*

 * Copyright 2019 NXP

 *

 * Header file for the DSP IPC implementation

 */



#ifndef _IMX_DSP_IPC_H

#define _IMX_DSP_IPC_H



#include <linux/device.h>

#include <linux/types.h>

#include <linux/mailbox_client.h>



#define DSP_MU_CHAN_NUM		4



struct imx_dsp_chan {

	struct imx_dsp_ipc *ipc;

	struct mbox_client cl;

	struct mbox_chan *ch;

	char *name;

	int idx;

};



struct imx_dsp_ops {

	void (*handle_reply)(struct imx_dsp_ipc *ipc);

	void (*handle_request)(struct imx_dsp_ipc *ipc);

};



struct imx_dsp_ipc {

	/* Host <-> DSP communication uses 2 txdb and 2 rxdb channels */

	struct imx_dsp_chan chans[DSP_MU_CHAN_NUM];

	struct device *dev;

	struct imx_dsp_ops *ops;

	void *private_data;

};



static inline void imx_dsp_set_data(struct imx_dsp_ipc *ipc, void *data)

{

	if (!ipc)

		return;



	ipc->private_data = data;

}



static inline void *imx_dsp_get_data(struct imx_dsp_ipc *ipc)

{

	if (!ipc)

		return NULL;



	return ipc->private_data;

}



#if IS_ENABLED(CONFIG_IMX_DSP)



int imx_dsp_ring_doorbell(struct imx_dsp_ipc *dsp, unsigned int chan_idx);



#else



static inline int imx_dsp_ring_doorbell(struct imx_dsp_ipc *ipc,

					unsigned int chan_idx)

{

	return -ENOTSUPP;

}



#endif

#endif /* _IMX_DSP_IPC_H */

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