[PATCH v22 31/38] ASoC: usb: Create SOC USB SND jack kcontrol

[Wesley Cheng <quic_wcheng@xxxxxxxxxxx>]

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@xxxxxxxxxxx>
---
 include/sound/soc-usb.h | 16 +++++++++++
 sound/soc/soc-usb.c     | 62 ++++++++++++++++++++++++++++++++++++++++-
 2 files changed, 77 insertions(+), 1 deletion(-)

diff --git a/include/sound/soc-usb.h b/include/sound/soc-usb.h
index c5aecdd0b006..8e94c1991819 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_kctl {
 	SND_SOC_USB_KCTL_CARD_ROUTE,
 	SND_SOC_USB_KCTL_PCM_ROUTE,
@@ -88,6 +90,9 @@ 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);
+int snd_soc_usb_disable_offload_jack(struct snd_soc_component *component);
 
 struct snd_soc_usb *snd_soc_usb_allocate_port(struct snd_soc_component *component,
 					      int num_streams, void *data);
@@ -143,6 +148,17 @@ static inline int snd_soc_usb_set_session_state(struct snd_soc_usb *usb,
 	return -EINVAL;
 }
 
+static inline int snd_soc_usb_setup_offload_jack(struct snd_soc_component *component,
+						 struct snd_soc_jack *jack)
+{
+	return -ENODEV;
+}
+
+static inline int snd_soc_usb_disable_offload_jack(struct snd_soc_component *component)
+{
+	return -ENODEV;
+}
+
 static inline struct snd_soc_usb *snd_soc_usb_allocate_port(
 					      struct snd_soc_component *component,
 					      int num_streams, void *data)
diff --git a/sound/soc/soc-usb.c b/sound/soc/soc-usb.c
index faacae8a6a5c..0baba34910b5 100644
--- a/sound/soc/soc-usb.c
+++ b/sound/soc/soc-usb.c
@@ -4,8 +4,10 @@
  */
 #include <linux/of.h>
 #include <linux/usb.h>
-#include <sound/soc.h>
+
+#include <sound/jack.h>
 #include <sound/soc-usb.h>
+
 #include "../usb/card.h"
 
 static DEFINE_MUTEX(ctx_mutex);
@@ -61,6 +63,64 @@ static struct snd_soc_usb *snd_soc_find_usb_ctx(struct device *dev)
 }
 
 /* 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 Playback 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_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
+ * @jack: jack structure to disable
+ *
+ * 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);
+
 static int snd_soc_usb_get_offload_card_status(struct snd_kcontrol *kcontrol,
 				   struct snd_ctl_elem_value *ucontrol)
 {