ASoC: SOF: Introduce IPC SOF client support

A client in the SOF (Sound Open Firmware) context is a driver that needs
to communicate with the DSP via IPC messages. The SOF core is responsible
for serializing the IPC messages to the DSP from the different clients.

One example of an SOF client would be an IPC test client that floods the
DSP with test IPC messages to validate if the serialization works as
expected.

Multi-client support will also add the ability to split the existing audio
cards into multiple ones, so as to e.g. to deal with HDMI with a dedicated
client instead of adding HDMI to all cards.

This patch introduces descriptors for SOF client driver and SOF client
device along with APIs for registering and unregistering a SOF client
driver, sending IPCs from a client device and accessing the SOF core
debugfs root entry.

Along with this, add a couple of new members to struct snd_sof_dev that
will be used for maintaining the list of clients.

Signed-off-by: Ranjani Sridharan <ranjani.sridharan@linux.intel.com>
Co-developed-by: Fred Oh <fred.oh@linux.intel.com>
Signed-off-by: Fred Oh <fred.oh@linux.intel.com>
Signed-off-by: Peter Ujfalusi <peter.ujfalusi@linux.intel.com>

Author: ujfalusi

sound/soc/sof/Kconfig

@@ -61,6 +61,13 @@ config SND_SOC_SOF_DEBUG_PROBES
 	  Say Y if you want to enable probes.
 	  If unsure, select "N".
 
+config SND_SOC_SOF_CLIENT
+	tristate
+	select AUXILIARY_BUS
+	help
+	  This option is not user-selectable but automagically handled by
+	  'select' statements at a higher level.
+
 config SND_SOC_SOF_DEVELOPER_SUPPORT
 	bool "SOF developer options support"
 	depends on EXPERT

sound/soc/sof/Makefile

@@ -2,6 +2,7 @@
 
 snd-sof-objs := core.o ops.o loader.o ipc.o pcm.o pm.o debug.o topology.o\
 		control.o trace.o iomem-utils.o sof-audio.o stream-ipc.o ipc4.o
+snd-sof-$(CONFIG_SND_SOC_SOF_CLIENT) += sof-client.o
 
 snd-sof-$(CONFIG_SND_SOC_SOF_DEBUG_PROBES) += sof-probes.o
 snd-sof-$(CONFIG_SND_SOC_SOF_COMPRESS) += compress.o

sound/soc/sof/core.c

@@ -122,6 +122,27 @@ void sof_print_oops_and_stack(struct snd_sof_dev *sdev, const char *level,
 }
 EXPORT_SYMBOL(sof_print_oops_and_stack);
 
+/* Helper to manage DSP state */
+void sof_set_fw_state(struct snd_sof_dev *sdev, enum sof_fw_state new_state)
+{
+	if (sdev->fw_state == new_state)
+		return;
+
+	dev_dbg(sdev->dev, "fw_state change: %d -> %d\n", sdev->fw_state, new_state);
+	sdev->fw_state = new_state;
+
+	switch (new_state) {
+	case SOF_FW_BOOT_NOT_STARTED:
+	case SOF_FW_BOOT_COMPLETE:
+	case SOF_FW_CRASHED:
+		sof_client_fw_state_dispatcher(sdev);
+		fallthrough;
+	default:
+		break;
+	}
+}
+EXPORT_SYMBOL(sof_set_fw_state);
+
 /*
  *			FW Boot State Transition Diagram
  *
@@ -266,6 +287,12 @@ static int sof_probe_continue(struct snd_sof_dev *sdev)
 		goto fw_trace_err;
 	}
 
+	ret = sof_register_clients(sdev);
+	if (ret < 0) {
+		dev_err(sdev->dev, "failed to register clients %d\n", ret);
+		goto sof_machine_err;
+	}
+
 	/*
 	 * Some platforms in SOF, ex: BYT, may not have their platform PM
 	 * callbacks set. Increment the usage count so as to
@@ -281,6 +308,8 @@ static int sof_probe_continue(struct snd_sof_dev *sdev)
 
 	return 0;
 
+sof_machine_err:
+	snd_sof_machine_unregister(sdev, plat_data);
 fw_trace_err:
 	snd_sof_free_trace(sdev);
 fw_run_err:
@@ -329,7 +358,6 @@ int snd_sof_device_probe(struct device *dev, struct snd_sof_pdata *plat_data)
 
 	sdev->pdata = plat_data;
 	sdev->first_boot = true;
-	sof_set_fw_state(sdev, SOF_FW_BOOT_NOT_STARTED);
 #if IS_ENABLED(CONFIG_SND_SOC_SOF_DEBUG_PROBES)
 	sdev->extractor_stream_tag = SOF_PROBE_INVALID_NODE_ID;
 #endif
@@ -350,9 +378,14 @@ int snd_sof_device_probe(struct device *dev, struct snd_sof_pdata *plat_data)
 	INIT_LIST_HEAD(&sdev->widget_list);
 	INIT_LIST_HEAD(&sdev->dai_list);
 	INIT_LIST_HEAD(&sdev->route_list);
+	INIT_LIST_HEAD(&sdev->ipc_client_list);
+	INIT_LIST_HEAD(&sdev->ipc_rx_handler_list);
+	INIT_LIST_HEAD(&sdev->fw_state_handler_list);
 	spin_lock_init(&sdev->ipc_lock);
 	spin_lock_init(&sdev->hw_lock);
 	mutex_init(&sdev->power_state_access);
+	mutex_init(&sdev->ipc_client_mutex);
+	mutex_init(&sdev->client_event_handler_mutex);
 
 	/* set default timeouts if none provided */
 	if (plat_data->desc->ipc_timeout == 0)
@@ -364,6 +397,8 @@ int snd_sof_device_probe(struct device *dev, struct snd_sof_pdata *plat_data)
 	else
 		sdev->boot_timeout = plat_data->desc->boot_timeout;
 
+	sof_set_fw_state(sdev, SOF_FW_BOOT_NOT_STARTED);
+
 	if (IS_ENABLED(CONFIG_SND_SOC_SOF_PROBE_WORK_QUEUE)) {
 		INIT_WORK(&sdev->probe_work, sof_probe_work);
 		schedule_work(&sdev->probe_work);
@@ -391,6 +426,12 @@ int snd_sof_device_remove(struct device *dev)
 	if (IS_ENABLED(CONFIG_SND_SOC_SOF_PROBE_WORK_QUEUE))
 		cancel_work_sync(&sdev->probe_work);
 
+	/*
+	 * Unregister any registered client device first before IPC and debugfs
+	 * to allow client drivers to be removed cleanly
+	 */
+	sof_unregister_clients(sdev);
+
 	/*
 	 * Unregister machine driver. This will unbind the snd_card which
 	 * will remove the component driver and unload the topology

sound/soc/sof/ipc.c

@@ -541,22 +541,25 @@ void snd_sof_ipc_msgs_rx(struct snd_sof_dev *sdev)
 		break;
 	}
 
-	if (rx_callback) {
-		/* read the full message as we have rx handler for it */
-		msg_buf = kmalloc(hdr.size, GFP_KERNEL);
-		if (!msg_buf)
-			return;
+	/* read the full message */
+	msg_buf = kmalloc(hdr.size, GFP_KERNEL);
+	if (!msg_buf)
+		return;
 
-		err = snd_sof_ipc_msg_data(sdev, NULL, msg_buf, hdr.size);
-		if (err < 0)
-			dev_err(sdev->dev, "%s: Failed to read message: %d\n",
-				__func__, err);
-		else
+	err = snd_sof_ipc_msg_data(sdev, NULL, msg_buf, hdr.size);
+	if (err < 0) {
+		dev_err(sdev->dev, "%s: Failed to read message: %d\n", __func__, err);
+	} else {
+		/* Call local handler for the message */
+		if (rx_callback)
 			rx_callback(sdev, msg_buf);
 
-		kfree(msg_buf);
+		/* Notify registered clients */
+		sof_client_ipc_rx_dispatcher(sdev, msg_buf);
 	}
 
+	kfree(msg_buf);
+
 	ipc_log_header(sdev->dev, "ipc rx done", hdr.cmd);
 }
 EXPORT_SYMBOL(snd_sof_ipc_msgs_rx);