[RFC,v2,11/22] ASoC: qcom: Add USB backend ASoC driver for Q6

diff --git a/include/sound/q6usboffload.h b/include/sound/q6usboffload.h
new file mode 100644
index 000000000000..e576808901d9
--- /dev/null
+++ b/include/sound/q6usboffload.h
@@ -0,0 +1,20 @@ 
+/* SPDX-License-Identifier: GPL-2.0
+ *
+ * linux/sound/q6usboffload.h -- QDSP6 USB offload
+ *
+ * Copyright (c) 2022 Qualcomm Innovation Center, Inc. All rights reserved.
+ */
+
+/**
+ * struct q6usb_offload
+ * @dev - dev handle to usb be
+ * @sid - streamID for iommu
+ * @intr_num - usb interrupter number
+ * @domain - allocated iommu domain
+ **/
+struct q6usb_offload {
+	struct device *dev;
+	u32 sid;
+	u32 intr_num;
+	struct iommu_domain *domain;
+};
diff --git a/sound/soc/qcom/Kconfig b/sound/soc/qcom/Kconfig
index 8c7398bc1ca8..d65c365116e5 100644
--- a/sound/soc/qcom/Kconfig
+++ b/sound/soc/qcom/Kconfig
@@ -111,6 +111,9 @@  config SND_SOC_QDSP6_APM
 config SND_SOC_QDSP6_PRM_LPASS_CLOCKS
 	tristate
 
+config SND_SOC_QDSP6_USB
+	tristate
+
 config SND_SOC_QDSP6_PRM
 	tristate
 	select SND_SOC_QDSP6_PRM_LPASS_CLOCKS
@@ -131,6 +134,7 @@  config SND_SOC_QDSP6
 	select SND_SOC_TOPOLOGY
 	select SND_SOC_QDSP6_APM
 	select SND_SOC_QDSP6_PRM
+	select SND_SOC_QDSP6_USB
 	help
 	 To add support for MSM QDSP6 Soc Audio.
 	 This will enable sound soc platform specific
diff --git a/sound/soc/qcom/qdsp6/Makefile b/sound/soc/qcom/qdsp6/Makefile
index 3963bf234664..c9457ee898d0 100644
--- a/sound/soc/qcom/qdsp6/Makefile
+++ b/sound/soc/qcom/qdsp6/Makefile
@@ -17,3 +17,4 @@  obj-$(CONFIG_SND_SOC_QDSP6_APM_DAI) += q6apm-dai.o
 obj-$(CONFIG_SND_SOC_QDSP6_APM_LPASS_DAI) += q6apm-lpass-dais.o
 obj-$(CONFIG_SND_SOC_QDSP6_PRM) += q6prm.o
 obj-$(CONFIG_SND_SOC_QDSP6_PRM_LPASS_CLOCKS) += q6prm-clocks.o
+obj-$(CONFIG_SND_SOC_QDSP6_USB) += q6usb.o
diff --git a/sound/soc/qcom/qdsp6/q6usb.c b/sound/soc/qcom/qdsp6/q6usb.c
new file mode 100644
index 000000000000..afbff66108bc
--- /dev/null
+++ b/sound/soc/qcom/qdsp6/q6usb.c
@@ -0,0 +1,231 @@ 
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (c) 2022 Qualcomm Innovation Center, Inc. All rights reserved.
+ */
+
+#include <linux/err.h>
+#include <linux/init.h>
+#include <linux/module.h>
+#include <linux/device.h>
+#include <linux/platform_device.h>
+#include <linux/slab.h>
+#include <linux/iommu.h>
+#include <linux/dma-mapping.h>
+#include <linux/dma-map-ops.h>
+
+#include <sound/pcm.h>
+#include <sound/soc.h>
+#include <sound/soc-usb.h>
+#include <sound/pcm_params.h>
+#include <sound/asound.h>
+#include <sound/q6usboffload.h>
+
+#include "q6dsp-lpass-ports.h"
+#include "q6afe.h"
+
+struct q6usb_port_data {
+	struct q6afe_usb_cfg usb_cfg;
+	struct snd_soc_usb *usb;
+	struct q6usb_offload priv;
+	int active_idx;
+};
+
+static const struct snd_soc_dapm_widget q6usb_dai_widgets[] = {
+	SND_SOC_DAPM_HP("USB_RX_BE", NULL),
+};
+
+static const struct snd_soc_dapm_route q6usb_dapm_routes[] = {
+	{"USB Playback", NULL, "USB_RX_BE"},
+};
+
+static int q6usb_hw_params(struct snd_pcm_substream *substream,
+			   struct snd_pcm_hw_params *params,
+			   struct snd_soc_dai *dai)
+{
+	return 0;
+}
+static const struct snd_soc_dai_ops q6usb_ops = {
+	.hw_params = q6usb_hw_params,
+};
+
+static struct snd_soc_dai_driver q6usb_be_dais[] = {
+	{
+		.playback = {
+			.stream_name = "USB BE RX",
+			.rates = SNDRV_PCM_RATE_8000 | SNDRV_PCM_RATE_11025 |
+				SNDRV_PCM_RATE_16000 | SNDRV_PCM_RATE_22050 |
+				SNDRV_PCM_RATE_32000 | SNDRV_PCM_RATE_44100 |
+				SNDRV_PCM_RATE_48000 | SNDRV_PCM_RATE_96000 |
+				SNDRV_PCM_RATE_192000,
+			.formats = SNDRV_PCM_FMTBIT_S16_LE | SNDRV_PCM_FMTBIT_S16_BE |
+				SNDRV_PCM_FMTBIT_U16_LE | SNDRV_PCM_FMTBIT_U16_BE |
+				SNDRV_PCM_FMTBIT_S24_LE | SNDRV_PCM_FMTBIT_S24_BE |
+				SNDRV_PCM_FMTBIT_U24_LE | SNDRV_PCM_FMTBIT_U24_BE,
+			.channels_min = 1,
+			.channels_max = 2,
+			.rate_max =     192000,
+			.rate_min =	8000,
+		},
+		.id = USB_RX,
+		.name = "USB_RX_BE",
+		.ops = &q6usb_ops,
+	},
+};
+
+static int q6usb_audio_ports_of_xlate_dai_name(struct snd_soc_component *component,
+					const struct of_phandle_args *args,
+					const char **dai_name)
+{
+	int id = args->args[0];
+	int ret = -EINVAL;
+	int i;
+
+	for (i = 0; i  < ARRAY_SIZE(q6usb_be_dais); i++) {
+		if (q6usb_be_dais[i].id == id) {
+			*dai_name = q6usb_be_dais[i].name;
+			ret = 0;
+			break;
+		}
+	}
+
+	return ret;
+}
+
+static int q6usb_component_probe(struct snd_soc_component *component)
+{
+	struct q6usb_port_data *data = dev_get_drvdata(component->dev);
+	struct snd_soc_dapm_context *dapm = snd_soc_component_get_dapm(component);
+
+	data->usb->component = component;
+
+	snd_soc_dapm_disable_pin(dapm, "USB_RX_BE");
+	snd_soc_dapm_sync(dapm);
+
+	return 0;
+}
+
+static const struct snd_soc_component_driver q6usb_dai_component = {
+	.probe = q6usb_component_probe,
+	.name = "q6usb-dai-component",
+	.dapm_widgets = q6usb_dai_widgets,
+	.num_dapm_widgets = ARRAY_SIZE(q6usb_dai_widgets),
+	.dapm_routes = q6usb_dapm_routes,
+	.num_dapm_routes = ARRAY_SIZE(q6usb_dapm_routes),
+	.of_xlate_dai_name = q6usb_audio_ports_of_xlate_dai_name,
+};
+
+static int q6usb_alsa_connection_cb(struct snd_soc_usb *usb, int card_idx,
+			int connected)
+{
+	struct snd_soc_dapm_context *dapm;
+	struct q6usb_port_data *data;
+
+	/* Check if routes to the backend have not yet been established */
+	if (!usb->component)
+		return -ENODEV;
+
+	dapm = snd_soc_component_get_dapm(usb->component);
+	data = dev_get_drvdata(usb->component->dev);
+
+	if (connected) {
+		snd_soc_dapm_enable_pin(dapm, "USB_RX_BE");
+		/* We only track the latest USB headset plugged in */
+		data->active_idx = card_idx;
+	} else {
+		snd_soc_dapm_disable_pin(dapm, "USB_RX_BE");
+	}
+	snd_soc_dapm_sync(dapm);
+
+	return 0;
+}
+
+static int q6usb_dai_dev_probe(struct platform_device *pdev)
+{
+	struct device_node *node = pdev->dev.of_node;
+	struct q6usb_port_data *data;
+	struct device *dev = &pdev->dev;
+	int ret;
+
+	data = devm_kzalloc(dev, sizeof(*data), GFP_KERNEL);
+	if (!data)
+		return -ENOMEM;
+
+	ret = of_property_read_u32(node, "qcom,usb-audio-stream-id",
+				&data->priv.sid);
+	if (ret) {
+		dev_err(&pdev->dev, "failed to read sid.\n");
+		return -ENODEV;
+	}
+
+	ret = of_property_read_u32(node, "qcom,usb-audio-intr-num",
+				&data->priv.intr_num);
+	if (ret) {
+		dev_err(&pdev->dev, "failed to read intr num.\n");
+		return -ENODEV;
+	}
+
+	data->priv.domain = iommu_domain_alloc(pdev->dev.bus);
+	if (!data->priv.domain) {
+		dev_err(&pdev->dev, "failed to allocate iommu domain\n");
+		return -ENODEV;
+	}
+
+	/* attach to external processor iommu */
+	ret = iommu_attach_device(data->priv.domain, &pdev->dev);
+	if (ret) {
+		dev_err(&pdev->dev, "failed to attach device ret = %d\n", ret);
+		goto free_domain;
+	}
+
+	data->usb = snd_soc_usb_add_port(dev, q6usb_alsa_connection_cb);
+	if (IS_ERR(data->usb)) {
+		dev_err(&pdev->dev, "failed to add usb port\n");
+		goto detach_device;
+	}
+
+	data->priv.dev = dev;
+	dev_set_drvdata(dev, data);
+	devm_snd_soc_register_component(dev, &q6usb_dai_component,
+					q6usb_be_dais, ARRAY_SIZE(q6usb_be_dais));
+	snd_soc_usb_set_priv_data(dev, &data->priv);
+
+	return 0;
+
+detach_device:
+	iommu_detach_device(data->priv.domain, &pdev->dev);
+free_domain:
+	iommu_domain_free(data->priv.domain);
+
+	return ret;
+}
+
+static int q6usb_dai_dev_remove(struct platform_device *pdev)
+{
+	struct q6usb_port_data *data = platform_get_drvdata(pdev);
+
+	iommu_detach_device(data->priv.domain, &pdev->dev);
+	iommu_domain_free(data->priv.domain);
+
+	snd_soc_usb_remove_port(&pdev->dev);
+
+	return 0;
+}
+
+static const struct of_device_id q6usb_dai_device_id[] = {
+	{ .compatible = "qcom,q6usb-dais" },
+	{},
+};
+MODULE_DEVICE_TABLE(of, q6usb_dai_device_id);
+
+static struct platform_driver q6usb_dai_platform_driver = {
+	.driver = {
+		.name = "q6usb-dai",
+		.of_match_table = of_match_ptr(q6usb_dai_device_id),
+	},
+	.probe = q6usb_dai_dev_probe,
+	.remove = q6usb_dai_dev_remove,
+};
+module_platform_driver(q6usb_dai_platform_driver);
+
+MODULE_DESCRIPTION("Q6 USB backend dai driver");
+MODULE_LICENSE("GPL");