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: Daniel Baluta <daniel.baluta@nxp.com>
Reviewed-by: Oleksij Rempel <o.rempel@pengutronix.de>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>

diff --git a/drivers/firmware/imx/Kconfig b/drivers/firmware/imx/Kconfig
index 42b566f8903fad18c15c3ba76b12422be79dd5dd..0dbee32da4c6d52ea3a84704245fee151ef37d65 100644 (file)
--- 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 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

diff --git a/drivers/firmware/imx/Makefile b/drivers/firmware/imx/Makefile
index 802c4ad8e8f96736d868c9588a51302b18ba5a7e..08bc9ddfbdfb5112b1a6c5983a159f0626fba00f 100644 (file)
--- 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 (file)
index 0000000..a43d2db
--- /dev/null
+++ b/drivers/firmware/imx/imx-dsp.c
@@ -0,0 +1,155 @@
+// 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");

diff --git a/include/linux/firmware/imx/dsp.h b/include/linux/firmware/imx/dsp.h
new file mode 100644 (file)
index 0000000..7562099
--- /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 */