[PATCH v12 21/41] ASoC: usb: Add PCM format check API for USB backend

[Wesley Cheng <quic_wcheng@xxxxxxxxxxx>]

Introduce a helper to check if a particular PCM format is supported by the
USB audio device connected.  If the USB audio device does not have an
audio profile which can support the requested format, then notify the USB
backend.

Signed-off-by: Wesley Cheng <quic_wcheng@xxxxxxxxxxx>
---
 include/sound/soc-usb.h |  2 ++
 sound/soc/soc-usb.c     | 25 +++++++++++++++++++++++++
 2 files changed, 27 insertions(+)

diff --git a/include/sound/soc-usb.h b/include/sound/soc-usb.h
index c0c6b5abacdf..d9fc83180c56 100644
--- a/include/sound/soc-usb.h
+++ b/include/sound/soc-usb.h
@@ -38,6 +38,8 @@ struct snd_soc_usb {
 };
 
 const char *snd_soc_usb_get_components_tag(bool playback);
+int snd_soc_usb_find_format(int card_idx, struct snd_pcm_hw_params *params,
+			int direction);
 
 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);
diff --git a/sound/soc/soc-usb.c b/sound/soc/soc-usb.c
index 5b127141f0a1..cad8e1d798e4 100644
--- a/sound/soc/soc-usb.c
+++ b/sound/soc/soc-usb.c
@@ -80,6 +80,31 @@ void *snd_soc_usb_find_priv_data(struct device *dev)
 }
 EXPORT_SYMBOL_GPL(snd_soc_usb_find_priv_data);
 
+/**
+ * snd_soc_usb_find_format() - Check if audio format is supported
+ * @card_idx: USB sound chip array index
+ * @params: PCM parameters
+ * @direction: capture or playback
+ *
+ * Ensure that a requested audio profile from the ASoC side is able to be
+ * supported by the USB device.
+ *
+ * Return 0 on success, negative on error.
+ *
+ */
+int snd_soc_usb_find_format(int card_idx, struct snd_pcm_hw_params *params,
+			int direction)
+{
+	struct snd_usb_stream *as;
+
+	as = snd_usb_find_suppported_substream(card_idx, params, direction);
+	if (!as)
+		return -EOPNOTSUPP;
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(snd_soc_usb_find_format);
+
 /**
  * snd_soc_usb_allocate_port() - allocate a SOC USB device
  * @component: USB DPCM backend DAI component