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
