[PATCH v10 33/41] ASoC: usb: Create SOC USB SND jack kcontrol

[Wesley Cheng <quic_wcheng@quicinc.com>]

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.

Signed-off-by: Wesley Cheng <quic_wcheng@quicinc.com>
---
 include/sound/soc-usb.h |  4 ++++
 sound/soc/soc-usb.c     | 37 +++++++++++++++++++++++++++++++++++++
 2 files changed, 41 insertions(+)

diff --git a/include/sound/soc-usb.h b/include/sound/soc-usb.h
index b0dbb89316fe..6bbd4339e8c5 100644
--- a/include/sound/soc-usb.h
+++ b/include/sound/soc-usb.h
@@ -6,6 +6,8 @@
 #ifndef __LINUX_SND_SOC_USB_H
 #define __LINUX_SND_SOC_USB_H
 
+#include <sound/soc.h>
+
 enum snd_soc_usb_dai_state {
 	SND_SOC_USB_IDLE,
 	SND_SOC_USB_PREPARED,
@@ -76,6 +78,8 @@ int snd_soc_usb_prepare_session(struct snd_soc_usb *usb, int card_idx, int pcm_i
 int snd_soc_usb_shutdown_session(struct snd_soc_usb *usb, int session_id);
 int snd_soc_usb_set_session_state(struct snd_soc_usb *usb, int session_id,
 				  enum snd_soc_usb_dai_state state);
+int snd_soc_usb_setup_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,
 			int num_supported_streams, void *data);
diff --git a/sound/soc/soc-usb.c b/sound/soc/soc-usb.c
index 50cd53db365f..7d202b0a2680 100644
--- a/sound/soc/soc-usb.c
+++ b/sound/soc/soc-usb.c
@@ -4,8 +4,11 @@
  */
 #include <linux/of.h>
 #include <linux/usb.h>
+
+#include <sound/jack.h>
 #include <sound/soc.h>
 #include <sound/soc-usb.h>
+
 #include "../usb/card.h"
 
 static DEFINE_MUTEX(ctx_mutex);
@@ -42,6 +45,40 @@ static struct snd_soc_usb *snd_soc_find_usb_ctx(struct device_node *node)
 }
 
 /* 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, "SNDUSB OFFLD Jack",
+					SND_JACK_HEADPHONE, jack);
+	if (ret < 0) {
+		dev_err(component->card->dev, "Unable to add USB offload jack\n");
+		return ret;
+	}
+
+	ret = snd_soc_component_set_jack(component, jack, NULL);
+	if (ret) {
+		dev_warn(component->card->dev, "Failed to set jack: %d\n", ret);
+		return ret;
+	}
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(snd_soc_usb_setup_offload_jack);
+
 static int snd_soc_usb_get_offload_status(struct snd_kcontrol *kcontrol,
 				   struct snd_ctl_elem_value *ucontrol)
 {