Hi Oleksij,
Any comments on this?
On Thu, Jun 27, 2019 at 11:14 AM Daniel Baluta <daniel.baluta@xxxxxxx> wrote:
>
> 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 driver 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 driver 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 drivers 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 driver on
> notification arrival from DSP.
>
> Signed-off-by: Daniel Baluta <daniel.baluta@xxxxxxx>
> ---
> drivers/firmware/imx/Kconfig | 11 +++
> drivers/firmware/imx/Makefile | 1 +
> drivers/firmware/imx/imx-dsp.c | 142 +++++++++++++++++++++++++++++++
> include/linux/firmware/imx/dsp.h | 67 +++++++++++++++
> 4 files changed, 221 insertions(+)
> create mode 100644 drivers/firmware/imx/imx-dsp.c
> create mode 100644 include/linux/firmware/imx/dsp.h
>
> diff --git a/drivers/firmware/imx/Kconfig b/drivers/firmware/imx/Kconfig
> index 42b566f8903f..ddb241708c31 100644
> --- a/drivers/firmware/imx/Kconfig
> +++ b/drivers/firmware/imx/Kconfig
> @@ -1,4 +1,15 @@
> # 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 CPU (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
> diff --git a/drivers/firmware/imx/Makefile b/drivers/firmware/imx/Makefile
> index 802c4ad8e8f9..08bc9ddfbdfb 100644
> --- a/drivers/firmware/imx/Makefile
> +++ b/drivers/firmware/imx/Makefile
> @@ -1,3 +1,4 @@
> # 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
> diff --git a/drivers/firmware/imx/imx-dsp.c b/drivers/firmware/imx/imx-dsp.c
> new file mode 100644
> index 000000000000..c4d34a2fbff3
> --- /dev/null
> +++ b/drivers/firmware/imx/imx-dsp.c
> @@ -0,0 +1,142 @@
> +// SPDX-License-Identifier: GPL-2.0+
> +/*
> + * Copyright 2019 NXP
> + * Author: Daniel Baluta <daniel.baluta@xxxxxxx>
> + *
> + * 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;
> +
> + 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 const struct of_device_id imx_dsp_match[] = {
> + { .compatible = "fsl,imx8qxp-dsp", },
> + { /* Sentinel */ }
> +};
> +
> +static struct platform_driver imx_dsp_driver = {
> + .driver = {
> + .name = "imx-dsp",
> + .of_match_table = imx_dsp_match,
> + },
> + .probe = imx_dsp_probe,
> +};
> +builtin_platform_driver(imx_dsp_driver);
> +
> +MODULE_AUTHOR("Daniel Baluta <daniel.baluta@xxxxxxx>");
> +MODULE_DESCRIPTION("IMX DSP IPC protocol driver");
> +MODULE_LICENSE("GPL v2");
> diff --git a/include/linux/firmware/imx/dsp.h b/include/linux/firmware/imx/dsp.h
> new file mode 100644
> index 000000000000..7562099c9e46
> --- /dev/null
> +++ b/include/linux/firmware/imx/dsp.h
> @@ -0,0 +1,67 @@
> +/* 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 */
> --
> 2.17.1
>
