commit 9d9dac161db94c2f75ed1d7b598d4a625bc20aa8
author Hemant Kumar <hemantk@codeaurora.org> Mon Mar 07 14:46:31 2016 -0800
committer Jack Pham <jackp@codeaurora.org> Thu Mar 23 15:59:07 2017 -0700
tree 6716fdba9b30b3e74136597044c2610b3c7360b0
parent 48cb3887af5a7948d3741960b58ff98a4709b386

sound: usb: Add helper APIs to enable audio stream

Adding helper API to find usb substream context information
using card number, pcm device number and direction. This usb
substream is used to enable/disable by issuing SET_ALT
command to device. Also add disconnect call back to perform
any clean up required.

Change-Id: I252f5171bd94b5ab096eb1a2f053f29a8c049c3b
Signed-off-by: Hemant Kumar <hemantk@codeaurora.org>
Signed-off-by: Jack Pham <jackp@codeaurora.org>

sound/usb/card.c

diff --git a/sound/usb/card.c b/sound/usb/card.c
index 90a4e68..33e5b67 100644
--- a/sound/usb/card.c
+++ b/sound/usb/card.c
@@ -113,6 +113,71 @@
 static struct snd_usb_audio *usb_chip[SNDRV_CARDS];
 static struct usb_driver usb_audio_driver;
 
+struct snd_usb_substream *find_snd_usb_substream(unsigned int card_num,
+	unsigned int pcm_idx, unsigned int direction, struct snd_usb_audio
+	**uchip, void (*disconnect_cb)(struct snd_usb_audio *chip))
+{
+	int idx;
+	struct snd_usb_stream *as;
+	struct snd_usb_substream *subs = NULL;
+	struct snd_usb_audio *chip = NULL;
+
+	mutex_lock(&register_mutex);
+	/*
+	 * legacy audio snd card number assignment is dynamic. Hence
+	 * search using chip->card->number
+	 */
+	for (idx = 0; idx < SNDRV_CARDS; idx++) {
+		if (!usb_chip[idx])
+			continue;
+		if (usb_chip[idx]->card->number == card_num) {
+			chip = usb_chip[idx];
+			break;
+		}
+	}
+
+	if (!chip || atomic_read(&chip->shutdown)) {
+		pr_debug("%s: instance of usb crad # %d does not exist\n",
+			__func__, card_num);
+		goto err;
+	}
+
+	if (pcm_idx >= chip->pcm_devs) {
+		pr_err("%s: invalid pcm dev number %u > %d\n", __func__,
+			pcm_idx, chip->pcm_devs);
+		goto err;
+	}
+
+	if (direction > SNDRV_PCM_STREAM_CAPTURE) {
+		pr_err("%s: invalid direction %u\n", __func__, direction);
+		goto err;
+	}
+
+	list_for_each_entry(as, &chip->pcm_list, list) {
+		if (as->pcm_index == pcm_idx) {
+			subs = &as->substream[direction];
+			if (subs->interface < 0 && !subs->data_endpoint &&
+				!subs->sync_endpoint) {
+				pr_debug("%s: stream disconnected, bail out\n",
+					__func__);
+				subs = NULL;
+				goto err;
+			}
+			goto done;
+		}
+	}
+
+done:
+	chip->card_num = card_num;
+	chip->disconnect_cb = disconnect_cb;
+err:
+	*uchip = chip;
+	if (!subs)
+		pr_debug("%s: substream instance not found\n", __func__);
+	mutex_unlock(&register_mutex);
+	return subs;
+}
+
 /*
  * disconnect streams
  * called from usb_audio_disconnect()
@@ -693,6 +758,8 @@
 	if (chip->num_interfaces <= 0) {
 		usb_chip[chip->index] = NULL;
 		mutex_unlock(&register_mutex);
+		if (chip->disconnect_cb)
+			chip->disconnect_cb(chip);
 		snd_card_free_when_closed(card);
 	} else {
 		mutex_unlock(&register_mutex);