[PATCH v22 29/38] ASoC: Introduce SND kcontrols to track USB offloading state

[Wesley Cheng]

Expose helpers in the SoC USB layer so components can update and keep track
of the offloading sessions.  This exposes a kcontrol to userspace, so that
applications can be aware of what the current USB offloading status is.
An example output using tinymix is:

USB offloading idle:
tinymix -D 0 get 'USB Offload Playback Route Card Status'
-->-1 (range -1->32)
tinymix -D 0 get 'USB Offload Playback Route PCM Status'
-->-1 (range -1->255)

USB offloading active(USB card#1 pcm#0):
tinymix -D 0 get 'USB Offload Playback Route Card Status'
-->1 (range -1->32)
tinymix -D 0 get 'USB Offload Playback Route PCM Status'
-->0 (range -1->255)

Signed-off-by: Wesley Cheng <quic_wcheng@xxxxxxxxxxx>
---
 include/sound/soc-usb.h |  46 ++++++++++
 sound/soc/soc-usb.c     | 193 ++++++++++++++++++++++++++++++++++++++++
 2 files changed, 239 insertions(+)

diff --git a/include/sound/soc-usb.h b/include/sound/soc-usb.h
index 495de5143db8..c5aecdd0b006 100644
--- a/include/sound/soc-usb.h
+++ b/include/sound/soc-usb.h
@@ -9,9 +9,29 @@
 enum snd_soc_usb_kctl {
 	SND_SOC_USB_KCTL_CARD_ROUTE,
 	SND_SOC_USB_KCTL_PCM_ROUTE,
+	SND_SOC_USB_KCTL_CARD_STATUS,
+	SND_SOC_USB_KCTL_PCM_STATUS,
 	SND_SOC_USB_KCTL_MAX,
 };
 
+enum snd_soc_usb_dai_state {
+	SND_SOC_USB_IDLE,
+	SND_SOC_USB_PREPARED,
+	SND_SOC_USB_RUNNING,
+};
+
+/**
+ * struct snd_soc_usb_session
+ * @active_card_idx - active offloaded sound card
+ * @active_pcm_idx - active offloaded PCM device
+ * @state - USB BE DAI link PCM state
+ */
+struct snd_soc_usb_session {
+	int active_card_idx;
+	int active_pcm_idx;
+	enum snd_soc_usb_dai_state state;
+};
+
 /**
  * struct snd_soc_usb_device
  * @card_idx - sound card index associated with USB device
@@ -31,6 +51,7 @@ struct snd_soc_usb_device {
  * @list - list head for SND SOC struct list
  * @component - reference to ASoC component
  * @kctl - list of kcontrols created
+ * @active_list - active sessions
  * @num_supported_streams - number of supported concurrent sessions
  * @connection_status_cb - callback to notify connection events
  * @put_offload_dev - callback to select USB sound card/PCM device
@@ -41,6 +62,7 @@ struct snd_soc_usb {
 	struct list_head list;
 	struct snd_soc_component *component;
 	struct snd_kcontrol *kctl[SND_SOC_USB_KCTL_MAX];
+	struct snd_soc_usb_session *active_list;
 	unsigned int num_supported_streams;
 	int (*connection_status_cb)(struct snd_soc_usb *usb,
 			struct snd_soc_usb_device *sdev, bool connected);
@@ -62,6 +84,11 @@ 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 *dev);
 
+int snd_soc_usb_prepare_session(struct snd_soc_usb *usb, int card_idx, int pcm_idx);
+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);
+
 struct snd_soc_usb *snd_soc_usb_allocate_port(struct snd_soc_component *component,
 					      int num_streams, void *data);
 void snd_soc_usb_free_port(struct snd_soc_usb *usb);
@@ -97,6 +124,25 @@ static inline void *snd_soc_usb_find_priv_data(struct device *dev)
 	return NULL;
 }
 
+static inline int snd_soc_usb_prepare_session(struct snd_soc_usb *usb, int card_idx,
+						int pcm_idx)
+{
+	return -EINVAL;
+}
+
+static inline int snd_soc_usb_shutdown_session(struct snd_soc_usb *usb,
+						int session_id)
+{
+	return -EINVAL;
+}
+
+static inline int snd_soc_usb_set_session_state(struct snd_soc_usb *usb,
+						int session_id,
+						enum snd_soc_usb_dai_state state)
+{
+	return -EINVAL;
+}
+
 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 ef84957014dd..faacae8a6a5c 100644
--- a/sound/soc/soc-usb.c
+++ b/sound/soc/soc-usb.c
@@ -61,6 +61,79 @@ static struct snd_soc_usb *snd_soc_find_usb_ctx(struct device *dev)
 }
 
 /* SOC USB sound kcontrols */
+static int snd_soc_usb_get_offload_card_status(struct snd_kcontrol *kcontrol,
+				   struct snd_ctl_elem_value *ucontrol)
+{
+	struct snd_soc_component *component = snd_kcontrol_chip(kcontrol);
+	struct snd_soc_usb *ctx = snd_soc_usb_ctx_lookup(component->dev->of_node);
+	int control_idx = 0;
+	int card_idx;
+	int i;
+
+	for (i = 0; i < ctx->num_supported_streams; i++) {
+		card_idx = -1;
+
+		if (ctx->active_list[i].state == SND_SOC_USB_RUNNING)
+			card_idx = ctx->active_list[i].active_card_idx;
+
+		ucontrol->value.integer.value[control_idx] = card_idx;
+		control_idx++;
+	}
+
+	return 0;
+}
+
+static int snd_soc_usb_offload_card_status_info(struct snd_kcontrol *kcontrol,
+			      struct snd_ctl_elem_info *uinfo)
+{
+	struct snd_soc_component *component = snd_kcontrol_chip(kcontrol);
+	struct snd_soc_usb *ctx = snd_soc_usb_ctx_lookup(component->dev->of_node);
+
+	uinfo->type = SNDRV_CTL_ELEM_TYPE_INTEGER;
+	uinfo->count = ctx->num_supported_streams;
+	uinfo->value.integer.min = -1;
+	uinfo->value.integer.max = SNDRV_CARDS;
+
+	return 0;
+}
+
+static int snd_soc_usb_get_offload_pcm_status(struct snd_kcontrol *kcontrol,
+				   struct snd_ctl_elem_value *ucontrol)
+{
+	struct snd_soc_component *component = snd_kcontrol_chip(kcontrol);
+	struct snd_soc_usb *ctx = snd_soc_usb_ctx_lookup(component->dev->of_node);
+	int control_idx = 0;
+	int pcm_idx;
+	int i;
+
+	for (i = 0; i < ctx->num_supported_streams; i++) {
+		pcm_idx = -1;
+
+		if (ctx->active_list[i].state == SND_SOC_USB_RUNNING)
+			pcm_idx = ctx->active_list[i].active_pcm_idx;
+
+		ucontrol->value.integer.value[control_idx] = pcm_idx;
+		control_idx++;
+	}
+
+	return 0;
+}
+
+static int snd_soc_usb_offload_pcm_status_info(struct snd_kcontrol *kcontrol,
+			      struct snd_ctl_elem_info *uinfo)
+{
+	struct snd_soc_component *component = snd_kcontrol_chip(kcontrol);
+	struct snd_soc_usb *ctx = snd_soc_usb_ctx_lookup(component->dev->of_node);
+
+	uinfo->type = SNDRV_CTL_ELEM_TYPE_INTEGER;
+	uinfo->count = ctx->num_supported_streams;
+	uinfo->value.integer.min = -1;
+	/* Arbitrary max value, as there is no 'limit' on number of PCM devices */
+	uinfo->value.integer.max = 0xff;
+
+	return 0;
+}
+
 static int soc_usb_put_offload_pcm_dev(struct snd_kcontrol *kcontrol,
 			      struct snd_ctl_elem_value *ucontrol)
 {
@@ -181,6 +254,22 @@ static const struct snd_kcontrol_new soc_usb_kcontrols[] = {
 		.get = soc_usb_get_offload_pcm_dev,
 		.put = soc_usb_put_offload_pcm_dev,
 	},
+	[SND_SOC_USB_KCTL_CARD_STATUS] = {
+		.iface = SNDRV_CTL_ELEM_IFACE_CARD,
+		.access = SNDRV_CTL_ELEM_ACCESS_READ,
+		.name = "USB Offload Playback Route Card Status",
+		.info = snd_soc_usb_offload_card_status_info,
+		.get = snd_soc_usb_get_offload_card_status,
+		.put = NULL,
+	},
+	[SND_SOC_USB_KCTL_PCM_STATUS] = {
+		.iface = SNDRV_CTL_ELEM_IFACE_CARD,
+		.access = SNDRV_CTL_ELEM_ACCESS_READ,
+		.name = "USB Offload Playback Route PCM Status",
+		.info = snd_soc_usb_offload_pcm_status_info,
+		.get = snd_soc_usb_get_offload_pcm_status,
+		.put = NULL,
+	},
 };
 
 static int snd_soc_usb_control_remove(struct snd_soc_usb *usb)
@@ -216,6 +305,102 @@ static int snd_soc_usb_control_init(struct snd_soc_usb *usb)
 	return ret;
 }
 
+/**
+ * snd_soc_usb_set_session_state() - Set the session state for a session
+ * @usb: SOC USB device
+ * @session_id: index to active_list
+ * @state: USB PCM device index
+ *
+ * Set the session state for an entry in active_list.  This should be only
+ * called after snd_soc_usb_prepare_session.
+ *
+ * Returns 0 on success, negative on error.
+ *
+ */
+int snd_soc_usb_set_session_state(struct snd_soc_usb *usb, int session_id,
+				  enum snd_soc_usb_dai_state state)
+{
+	if (session_id < 0 || session_id >= usb->num_supported_streams)
+		return -EINVAL;
+
+	mutex_lock(&ctx_mutex);
+	if (usb->active_list[session_id].state == state) {
+		mutex_unlock(&ctx_mutex);
+		return 0;
+	}
+
+	usb->active_list[session_id].state = state;
+	mutex_unlock(&ctx_mutex);
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(snd_soc_usb_set_session_state);
+
+/**
+ * snd_soc_usb_prepare_session() - Find and prepare a session
+ * @usb: SOC USB device
+ * @card_idx: USB card index
+ * @pcm_idx: USB PCM device index
+ *
+ * Find an open active session slot on the SOC USB device.  If all slots
+ * are busy, return an error.  If not, claim the slot and place it into
+ * the SND_SOC_USB_PREPARED state.  This should be called first before
+ * calling snd_soc_usb_set_session_state or snd_soc_usb_shutdown_session.
+ *
+ * Returns the session id (index) to active_list, negative on error.
+ *
+ */
+int snd_soc_usb_prepare_session(struct snd_soc_usb *usb, int card_idx, int pcm_idx)
+{
+	int i;
+
+	mutex_lock(&ctx_mutex);
+	for (i = 0; i < usb->num_supported_streams; i++) {
+		if (usb->active_list[i].state == SND_SOC_USB_IDLE) {
+			usb->active_list[i].active_card_idx = card_idx;
+			usb->active_list[i].active_pcm_idx = pcm_idx;
+			usb->active_list[i].state = SND_SOC_USB_PREPARED;
+			mutex_unlock(&ctx_mutex);
+			return i;
+		}
+	}
+	mutex_unlock(&ctx_mutex);
+
+	return -EBUSY;
+}
+EXPORT_SYMBOL_GPL(snd_soc_usb_prepare_session);
+
+/**
+ * snd_soc_usb_shutdown_session() - Set USB SOC to idle state
+ * @usb: SOC USB device
+ * @session_id: index to active_list
+ *
+ * Place the session specified by session_id into the idle/shutdown state.
+ *
+ */
+int snd_soc_usb_shutdown_session(struct snd_soc_usb *usb, int session_id)
+{
+	return snd_soc_usb_set_session_state(usb, session_id, SND_SOC_USB_IDLE);
+}
+EXPORT_SYMBOL_GPL(snd_soc_usb_shutdown_session);
+
+/**
+ * snd_soc_usb_get_components_tag() - Retrieve SOC USB component tag
+ * @playback: direction of audio stream
+ *
+ * Returns the USB offload component tag used in the ASoC components
+ * string.
+ *
+ */
+const char *snd_soc_usb_get_components_tag(bool playback)
+{
+	if (playback)
+		return "usbplaybackoffload: 1";
+	else
+		return "usbcaptureoffload : 1";
+}
+EXPORT_SYMBOL_GPL(snd_soc_usb_get_components_tag);
+
 /**
  * snd_soc_usb_find_priv_data() - Retrieve private data stored
  * @dev: device reference
@@ -277,6 +462,13 @@ struct snd_soc_usb *snd_soc_usb_allocate_port(struct snd_soc_component *componen
 	if (!usb)
 		return ERR_PTR(-ENOMEM);
 
+	usb->active_list = kcalloc(num_streams, sizeof(struct snd_soc_usb_session),
+				   GFP_KERNEL);
+	if (!usb->active_list) {
+		kfree(usb);
+		return ERR_PTR(-ENOMEM);
+	}
+
 	usb->component = component;
 	usb->priv_data = data;
 	usb->num_supported_streams = num_streams;
@@ -295,6 +487,7 @@ EXPORT_SYMBOL_GPL(snd_soc_usb_allocate_port);
 void snd_soc_usb_free_port(struct snd_soc_usb *usb)
 {
 	snd_soc_usb_remove_port(usb);
+	kfree(usb->active_list);
 	kfree(usb);
 }
 EXPORT_SYMBOL_GPL(snd_soc_usb_free_port);