From: Daniel Baluta <[email protected]>
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 <[email protected]>
---
drivers/firmware/imx/Kconfig | 11 ++
drivers/firmware/imx/Makefile | 1 +
drivers/firmware/imx/imx-dsp.c | 167 +++++++++++++++++++++++++++++++
include/linux/firmware/imx/dsp.h | 61 +++++++++++
4 files changed, 240 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..383996b679a8 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..953fd364ad76
--- /dev/null
+++ b/drivers/firmware/imx/imx-dsp.c
@@ -0,0 +1,167 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * Copyright 2018 NXP
+ * Author: Daniel Baluta <[email protected]>
+ *
+ * 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>
+
+static struct imx_dsp_ipc *imx_dsp_handle;
+
+/*
+ * Get the default handle used by DSP
+ */
+int imx_dsp_get_handle(struct imx_dsp_ipc **ipc)
+{
+ if (!imx_dsp_handle)
+ return -EPROBE_DEFER;
+
+ *ipc = imx_dsp_handle;
+ return 0;
+}
+EXPORT_SYMBOL(imx_dsp_get_handle);
+
+void imx_dsp_set_data(struct imx_dsp_ipc *ipc, void *data)
+{
+ if (!ipc)
+ return;
+
+ ipc->private_data = data;
+}
+EXPORT_SYMBOL(imx_dsp_set_data);
+
+void *imx_dsp_get_data(struct imx_dsp_ipc *ipc)
+{
+ if (!ipc)
+ return NULL;
+
+ return ipc->private_data;
+}
+EXPORT_SYMBOL(imx_dsp_get_data);
+
+/*
+ * 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;
+
+ 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);
+ return ret;
+ }
+
+ 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;
+
+ imx_dsp_handle = dsp_ipc;
+
+ dev_info(dev, "NXP i.MX DSP IPC initialized\n");
+
+ return devm_of_platform_populate(dev);
+}
+
+static const struct of_device_id imx_dsp_match[] = {
+ { .compatible = "fsl,imx-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 <[email protected]>");
+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..75637d8fab34
--- /dev/null
+++ b/include/linux/firmware/imx/dsp.h
@@ -0,0 +1,61 @@
+/* SPDX-License-Identifier: GPL-2.0+ */
+/*
+ * Copyright 2018 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;
+ 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;
+};
+
+#if IS_ENABLED(CONFIG_IMX_DSP)
+
+int imx_dsp_ring_doorbell(struct imx_dsp_ipc *dsp, unsigned int chan_idx);
+int imx_dsp_get_handle(struct imx_dsp_ipc **ipc);
+void imx_dsp_set_data(struct imx_dsp_ipc *ipc, void *data);
+void *imx_dsp_get_data(struct imx_dsp_ipc *ipc);
+
+#else
+
+static inline int imx_dsp_get_handle(struct imx_dsp_ipc **ipc)
+{
+ return -EIO;
+}
+
+static inline int imx_dsp_ring_doorbell(struct imx_dsp_ipc *ipc,
+ unsigned int chan_idx)
+{
+ return -EIO;
+}
+
+void imx_dsp_set_data(struct imx_dsp_ipc *ipc, void *data) { }
+void *imx_dsp_get_data(struct imx_dsp_ipc *ipc) { return NULL; }
+
+#endif
+#endif /* _IMX_DSP_IPC_H */
--
2.17.1
Hi Daniel,
please, see my review inline.
On Fri, Jun 14, 2019 at 04:16:49PM +0800, [email protected] wrote:
> From: Daniel Baluta <[email protected]>
>
> 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 <[email protected]>
> ---
> drivers/firmware/imx/Kconfig | 11 ++
> drivers/firmware/imx/Makefile | 1 +
> drivers/firmware/imx/imx-dsp.c | 167 +++++++++++++++++++++++++++++++
> include/linux/firmware/imx/dsp.h | 61 +++++++++++
> 4 files changed, 240 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..383996b679a8 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..953fd364ad76
> --- /dev/null
> +++ b/drivers/firmware/imx/imx-dsp.c
> @@ -0,0 +1,167 @@
> +// SPDX-License-Identifier: GPL-2.0+
> +/*
> + * Copyright 2018 NXP
> + * Author: Daniel Baluta <[email protected]>
> + *
> + * 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>
> +
> +static struct imx_dsp_ipc *imx_dsp_handle;
> +
> +/*
> + * Get the default handle used by DSP
> + */
> +int imx_dsp_get_handle(struct imx_dsp_ipc **ipc)
> +{
> + if (!imx_dsp_handle)
> + return -EPROBE_DEFER;
> +
> + *ipc = imx_dsp_handle;
> + return 0;
> +}
> +EXPORT_SYMBOL(imx_dsp_get_handle);
Please, extract needed device or handle form device tree. The consumer
should pars own device tree node and get the phandle to the dsp node.
> +void imx_dsp_set_data(struct imx_dsp_ipc *ipc, void *data)
> +{
> + if (!ipc)
> + return;
> +
> + ipc->private_data = data;
> +}
> +EXPORT_SYMBOL(imx_dsp_set_data);
> +
> +void *imx_dsp_get_data(struct imx_dsp_ipc *ipc)
> +{
> + if (!ipc)
> + return NULL;
> +
> + return ipc->private_data;
> +}
> +EXPORT_SYMBOL(imx_dsp_get_data);
> +
> +/*
> + * 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;
On this test idx may overflow. DSP_MU_CHAN_NUM is 4, means idx can be:
0, 1, 2, 3. In you case idx == 4 is allowed, so the caller will be able
to corrupt the rest of imx_dsp_ipc struct.
> + 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;
> +
> + 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);
> + return ret;
On the error you will leak the memory previously allocated chan_name.
And you should call mbox_free_channel() for each previously registered
channel in this loop.
> + }
> +
> + 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;
> +
> + imx_dsp_handle = dsp_ipc;
bad idea. What happens if multiple dsp nodes are registered in the
device tree?
> + dev_info(dev, "NXP i.MX DSP IPC initialized\n");
> +
> + return devm_of_platform_populate(dev);
> +}
> +
> +static const struct of_device_id imx_dsp_match[] = {
> + { .compatible = "fsl,imx-dsp", },
i would prefer to have chip name in the compatible. For example
fsl,imx8qm-dsp. Soon or later we will need to define some quirks
for on or another chip.
> + { /* 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 <[email protected]>");
> +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..75637d8fab34
> --- /dev/null
> +++ b/include/linux/firmware/imx/dsp.h
> @@ -0,0 +1,61 @@
> +/* SPDX-License-Identifier: GPL-2.0+ */
> +/*
> + * Copyright 2018 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;
> + 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;
> +};
> +
> +#if IS_ENABLED(CONFIG_IMX_DSP)
> +
> +int imx_dsp_ring_doorbell(struct imx_dsp_ipc *dsp, unsigned int chan_idx);
> +int imx_dsp_get_handle(struct imx_dsp_ipc **ipc);
> +void imx_dsp_set_data(struct imx_dsp_ipc *ipc, void *data);
> +void *imx_dsp_get_data(struct imx_dsp_ipc *ipc);
> +
> +#else
> +
> +static inline int imx_dsp_get_handle(struct imx_dsp_ipc **ipc)
> +{
> + return -EIO;
please, use -ENOTSUPP instead.
> +}
> +
> +static inline int imx_dsp_ring_doorbell(struct imx_dsp_ipc *ipc,
> + unsigned int chan_idx)
> +{
> + return -EIO;
> +}
> +
> +void imx_dsp_set_data(struct imx_dsp_ipc *ipc, void *data) { }
> +void *imx_dsp_get_data(struct imx_dsp_ipc *ipc) { return NULL; }
> +
> +#endif
> +#endif /* _IMX_DSP_IPC_H */
> --
> 2.17.1
>
>
--
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On Fri, Jun 14, 2019 at 12:08 PM Oleksij Rempel <[email protected]> wrote:
>
> Hi Daniel,
>
> please, see my review inline.
Thanks Oleksij for review. See my answers inline.
>
> On Fri, Jun 14, 2019 at 04:16:49PM +0800, [email protected] wrote:
> > From: Daniel Baluta <[email protected]>
> >
> > 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 <[email protected]>
> > ---
> > drivers/firmware/imx/Kconfig | 11 ++
> > drivers/firmware/imx/Makefile | 1 +
> > drivers/firmware/imx/imx-dsp.c | 167 +++++++++++++++++++++++++++++++
> > include/linux/firmware/imx/dsp.h | 61 +++++++++++
> > 4 files changed, 240 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..383996b679a8 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..953fd364ad76
> > --- /dev/null
> > +++ b/drivers/firmware/imx/imx-dsp.c
> > @@ -0,0 +1,167 @@
> > +// SPDX-License-Identifier: GPL-2.0+
> > +/*
> > + * Copyright 2018 NXP
> > + * Author: Daniel Baluta <[email protected]>
> > + *
> > + * 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>
> > +
> > +static struct imx_dsp_ipc *imx_dsp_handle;
> > +
> > +/*
> > + * Get the default handle used by DSP
> > + */
> > +int imx_dsp_get_handle(struct imx_dsp_ipc **ipc)
> > +{
> > + if (!imx_dsp_handle)
> > + return -EPROBE_DEFER;
> > +
> > + *ipc = imx_dsp_handle;
> > + return 0;
> > +}
> > +EXPORT_SYMBOL(imx_dsp_get_handle);
>
> Please, extract needed device or handle form device tree. The consumer
> should pars own device tree node and get the phandle to the dsp node.
I understand the idea, but I'm not sure how this can be done.
imx_dsp_handle is just a pointer to the memory allocated in imx_dsp_probe.
I assume that consumer might have access to this driver's
platform_device dev and
we can hive the imx_dsp_ipc handle inside some sort of private date. I will
investigate this. So far I have followed the approach taken in
drivers/firmware/imx/imx-scu.c
>
> > +void imx_dsp_set_data(struct imx_dsp_ipc *ipc, void *data)
> > +{
> > + if (!ipc)
> > + return;
> > +
> > + ipc->private_data = data;
> > +}
> > +EXPORT_SYMBOL(imx_dsp_set_data);
> > +
> > +void *imx_dsp_get_data(struct imx_dsp_ipc *ipc)
> > +{
> > + if (!ipc)
> > + return NULL;
> > +
> > + return ipc->private_data;
> > +}
> > +EXPORT_SYMBOL(imx_dsp_get_data);
> > +
> > +/*
> > + * 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;
>
> On this test idx may overflow. DSP_MU_CHAN_NUM is 4, means idx can be:
> 0, 1, 2, 3. In you case idx == 4 is allowed, so the caller will be able
> to corrupt the rest of imx_dsp_ipc struct.
Indeed, you are right! Will fix in v2.
>
> > + 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;
> > +
> > + 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);
> > + return ret;
>
> On the error you will leak the memory previously allocated chan_name.
> And you should call mbox_free_channel() for each previously registered
> channel in this loop.
Will fix in v2.
>
> > + }
> > +
> > + 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;
> > +
> > + imx_dsp_handle = dsp_ipc;
>
> bad idea. What happens if multiple dsp nodes are registered in the
> device tree?
True. Altough we have only one DSP. Having that global variable seemed
a very idea from the start. Will need to fix that also in imx-scu.c
>
> > + dev_info(dev, "NXP i.MX DSP IPC initialized\n");
> > +
> > + return devm_of_platform_populate(dev);
> > +}
> > +
> > +static const struct of_device_id imx_dsp_match[] = {
> > + { .compatible = "fsl,imx-dsp", },
>
> i would prefer to have chip name in the compatible. For example
> fsl,imx8qm-dsp. Soon or later we will need to define some quirks
> for on or another chip.
I see. Will fix in v2.
>
> > + { /* 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 <[email protected]>");
> > +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..75637d8fab34
> > --- /dev/null
> > +++ b/include/linux/firmware/imx/dsp.h
> > @@ -0,0 +1,61 @@
> > +/* SPDX-License-Identifier: GPL-2.0+ */
> > +/*
> > + * Copyright 2018 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;
> > + 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;
> > +};
> > +
> > +#if IS_ENABLED(CONFIG_IMX_DSP)
> > +
> > +int imx_dsp_ring_doorbell(struct imx_dsp_ipc *dsp, unsigned int chan_idx);
> > +int imx_dsp_get_handle(struct imx_dsp_ipc **ipc);
> > +void imx_dsp_set_data(struct imx_dsp_ipc *ipc, void *data);
> > +void *imx_dsp_get_data(struct imx_dsp_ipc *ipc);
> > +
> > +#else
> > +
> > +static inline int imx_dsp_get_handle(struct imx_dsp_ipc **ipc)
> > +{
> > + return -EIO;
>
> please, use -ENOTSUPP instead.
Makes sense. Will fix in v2.
thanks,
Daniel.