[PATCH v13 43/53] ASoC: Add SND kcontrol for fetching USB offload status

Wesley Cheng
2024-02-03T02:37:51Z

Add a kcontrol to the platform sound card to fetch the current offload
status. This can allow for userspace to ensure/check which USB SND
resources are actually busy versus having to attempt opening the USB SND
devices, which will result in an error if offloading is active.

Signed-off-by: Wesley Cheng <quic_wcheng@quicinc.com>
---
include/sound/soc-usb.h | 27 ++++++++
sound/soc/soc-usb.c | 150 +++++++++++++++++++++++++++++++++++++++-
2 files changed, 175 insertions(+), 2 deletions(-)

diff --git a/include/sound/soc-usb.h b/include/sound/soc-usb.h
index 20d7b32bba07..c05d9b2f5c90 100644
--- a/include/sound/soc-usb.h
+++ b/include/sound/soc-usb.h
@@ -6,6 +6,24 @@
#ifndef __LINUX_SND_SOC_USB_H
#define __LINUX_SND_SOC_USB_H

+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
@@ -25,6 +43,8 @@ struct snd_soc_usb_device {
* @list - list head for SND SOC struct list
* @dev - USB backend device reference
* @component - reference to ASoC component
+ * @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
* @get_offload_dev - callback to fetch selected USB sound card/PCM device
@@ -33,6 +53,8 @@ struct snd_soc_usb_device {
struct snd_soc_usb {
struct list_head list;
struct snd_soc_component *component;
+ 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);
int (*put_offload_dev)(struct snd_kcontrol *kcontrol,
@@ -50,6 +72,11 @@ 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_supported_streams, void *data);
void snd_soc_usb_free_port(struct snd_soc_usb *usb);
diff --git a/sound/soc/soc-usb.c b/sound/soc/soc-usb.c
index c568c67e3e4a..9c082129cb9f 100644
--- a/sound/soc/soc-usb.c
+++ b/sound/soc/soc-usb.c
@@ -42,11 +42,62 @@ static struct snd_soc_usb *snd_soc_find_usb_ctx(struct device_node *node)
}

/* SOC USB sound kcontrols */
+static int snd_soc_usb_get_offload_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_find_usb_ctx(component->dev->of_node);
+ int control_idx = 0;
+ int pcm_idx;
+ int card_idx;
+ int i;
+
+ for (i = 0; i < ctx->num_supported_streams; i++) {
+ card_idx = -1;
+ pcm_idx = -1;
+
+ if (ctx->active_list[i].state == SND_SOC_USB_RUNNING) {
+ card_idx = ctx->active_list[i].active_card_idx;
+ pcm_idx = ctx->active_list[i].active_pcm_idx;
+ }
+
+ ucontrol->value.integer.value[control_idx] = card_idx;
+ control_idx++;
+ ucontrol->value.integer.value[control_idx] = pcm_idx;
+ control_idx++;
+ }
+
+ return 0;
+}
+
+static int snd_soc_usb_offload_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_find_usb_ctx(component->dev->of_node);
+
+ uinfo->type = SNDRV_CTL_ELEM_TYPE_INTEGER;
+ uinfo->count = 2*ctx->num_supported_streams;
+ uinfo->value.integer.min = -1;
+ uinfo->value.integer.max = SNDRV_CARDS;
+
+ return 0;
+}
+
+static const struct snd_kcontrol_new soc_usb_status_ctrl = {
+ .iface = SNDRV_CTL_ELEM_IFACE_CARD,
+ .access = SNDRV_CTL_ELEM_ACCESS_READ,
+ .name = "SNDUSB OFFLD playback status",
+ .info = snd_soc_usb_offload_status_info,
+ .get = snd_soc_usb_get_offload_status,
+ .put = NULL,
+};
+
static int soc_usb_put_offload_dev(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_find_priv_data(component->dev);
+ struct snd_soc_usb *ctx = snd_soc_find_usb_ctx(component->dev->of_node);
int ret = 0;

mutex_lock(&ctx_mutex);
@@ -61,7 +112,7 @@ static int soc_usb_get_offload_dev(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_find_priv_data(component->dev);
+ struct snd_soc_usb *ctx = snd_soc_find_usb_ctx(component->dev->of_node);
int ret = 0;

mutex_lock(&ctx_mutex);
@@ -95,10 +146,96 @@ static const struct snd_kcontrol_new soc_usb_dev_ctrl = {

static int snd_soc_usb_control_init(struct snd_soc_component *component)
{
+ int ret;
+
+ ret = snd_ctl_add(component->card->snd_card,
+ snd_ctl_new1(&soc_usb_status_ctrl, component));
+ if (ret < 0)
+ return ret;
+
return snd_ctl_add(component->card->snd_card,
snd_ctl_new1(&soc_usb_dev_ctrl, component));
}

+/**
+ * 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
@@ -185,8 +322,16 @@ 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;

return usb;
}
@@ -202,6 +347,7 @@ 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);