Expose API for creation of a jack control for notifying of available
devices that are plugged in/discovered, and that support offloading.  This
allows for control names to be standardized across implementations of USB
audio offloading.

Reviewed-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
Signed-off-by: Wesley Cheng <quic_wcheng@quicinc.com>
---
 include/sound/soc-usb.h | 23 +++++++++++
 sound/soc/soc-usb.c     | 89 +++++++++++++++++++++++++++++++++++++++++
 2 files changed, 112 insertions(+)

diff --git a/include/sound/soc-usb.h b/include/sound/soc-usb.h
index db9ff0b4191d..587ea07a8cf5 100644
--- a/include/sound/soc-usb.h
+++ b/include/sound/soc-usb.h
@@ -56,6 +56,12 @@ int snd_soc_usb_connect(struct device *usbdev, struct snd_soc_usb_device *sdev);
 int snd_soc_usb_disconnect(struct device *usbdev, struct snd_soc_usb_device *sdev);
 void *snd_soc_usb_find_priv_data(struct device *usbdev);
 
+int snd_soc_usb_setup_offload_jack(struct snd_soc_component *component,
+				   struct snd_soc_jack *jack);
+int snd_soc_usb_disable_offload_jack(struct snd_soc_component *component);
+int snd_soc_usb_enable_offload_jack(struct snd_soc_component *component,
+				    struct snd_soc_jack *jack);
+
 struct snd_soc_usb *snd_soc_usb_allocate_port(struct snd_soc_component *component,
 					      void *data);
 void snd_soc_usb_free_port(struct snd_soc_usb *usb);
@@ -86,6 +92,23 @@ static inline void *snd_soc_usb_find_priv_data(struct device *usbdev)
 	return NULL;
 }
 
+static inline int snd_soc_usb_setup_offload_jack(struct snd_soc_component *component,
+						 struct snd_soc_jack *jack)
+{
+	return 0;
+}
+
+static inline int snd_soc_usb_disable_offload_jack(struct snd_soc_component *component)
+{
+	return 0;
+}
+
+static inline int snd_soc_usb_enable_offload_jack(struct snd_soc_component *component,
+						  struct snd_soc_jack *jack)
+{
+	return 0;
+}
+
 static inline struct snd_soc_usb *
 snd_soc_usb_allocate_port(struct snd_soc_component *component, void *data)
 {
diff --git a/sound/soc/soc-usb.c b/sound/soc/soc-usb.c
index c63033468e4a..ab914878e101 100644
--- a/sound/soc/soc-usb.c
+++ b/sound/soc/soc-usb.c
@@ -4,7 +4,10 @@
  */
 #include <linux/of.h>
 #include <linux/usb.h>
+
+#include <sound/jack.h>
 #include <sound/soc-usb.h>
+
 #include "../usb/card.h"
 
 static DEFINE_MUTEX(ctx_mutex);
@@ -56,6 +59,92 @@ static struct snd_soc_usb *snd_soc_find_usb_ctx(struct device *dev)
 	return ctx ? ctx : NULL;
 }
 
+/* SOC USB sound kcontrols */
+/**
+ * snd_soc_usb_setup_offload_jack() - Create USB offloading jack
+ * @component: USB DPCM backend DAI component
+ * @jack: jack structure to create
+ *
+ * Creates a jack device for notifying userspace of the availability
+ * of an offload capable device.
+ *
+ * Returns 0 on success, negative on error.
+ *
+ */
+int snd_soc_usb_setup_offload_jack(struct snd_soc_component *component,
+				   struct snd_soc_jack *jack)
+{
+	int ret;
+
+	ret = snd_soc_card_jack_new(component->card, "USB Offload Jack",
+				    SND_JACK_USB, jack);
+	if (ret < 0) {
+		dev_err(component->card->dev, "Unable to add USB offload jack: %d\n",
+			ret);
+		return ret;
+	}
+
+	ret = snd_soc_component_set_jack(component, jack, NULL);
+	if (ret) {
+		dev_err(component->card->dev, "Failed to set jack: %d\n", ret);
+		return ret;
+	}
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(snd_soc_usb_setup_offload_jack);
+
+/**
+ * snd_soc_usb_disable_offload_jack() - Disables USB offloading jack
+ * @component: USB DPCM backend DAI component
+ *
+ * Disables the offload jack device, so that further connection events
+ * won't be notified.
+ *
+ * Returns 0 on success, negative on error.
+ *
+ */
+int snd_soc_usb_disable_offload_jack(struct snd_soc_component *component)
+{
+	int ret;
+
+	ret = snd_soc_component_set_jack(component, NULL, NULL);
+	if (ret) {
+		dev_err(component->card->dev, "Failed to disable jack: %d\n", ret);
+		return ret;
+	}
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(snd_soc_usb_disable_offload_jack);
+
+/**
+ * snd_soc_usb_enable_offload_jack() - Enables USB offloading jack
+ * @component: USB DPCM backend DAI component
+ * @jack: offload jack to enable
+ *
+ * Enables the offload jack device, so that further connection events
+ * will be notified.  This is the complement to
+ * snd_soc_usb_disable_offload_jack().
+ *
+ * Returns 0 on success, negative on error.
+ *
+ */
+int snd_soc_usb_enable_offload_jack(struct snd_soc_component *component,
+				    struct snd_soc_jack *jack)
+{
+	int ret;
+
+	ret = snd_soc_component_set_jack(component, jack, NULL);
+	if (ret) {
+		dev_err(component->card->dev, "Failed to enable jack: %d\n", ret);
+		return ret;
+	}
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(snd_soc_usb_enable_offload_jack);
+
 /**
  * snd_soc_usb_find_priv_data() - Retrieve private data stored
  * @usbdev: device reference