[PATCH 1/6] staging: most: sound: create one sound card w/ multiple PCM devices per MOST device

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This patch avoids that a sound card is created and registered with ALSA
every time a channel is being linked. Instead the channels are hooked on
the same card, which is registered not until the final link has been added
to the component.

Signed-off-by: Christian Gromm <christian.gromm@xxxxxxxxxxxxx>
---
 drivers/staging/most/sound/sound.c | 127 +++++++++++++++++++++++++------------
 1 file changed, 87 insertions(+), 40 deletions(-)

diff --git a/drivers/staging/most/sound/sound.c b/drivers/staging/most/sound/sound.c
index 89b02fc..41bcd2c 100644
--- a/drivers/staging/most/sound/sound.c
+++ b/drivers/staging/most/sound/sound.c
@@ -10,6 +10,7 @@
 #include <linux/module.h>
 #include <linux/printk.h>
 #include <linux/kernel.h>
+#include <linux/slab.h>
 #include <linux/init.h>
 #include <sound/core.h>
 #include <sound/pcm.h>
@@ -20,7 +21,6 @@
 
 #define DRIVER_NAME "sound"
 
-static struct list_head dev_list;
 static struct core_component comp;
 
 /**
@@ -56,6 +56,17 @@ struct channel {
 	void (*copy_fn)(void *alsa, void *most, unsigned int bytes);
 };
 
+struct sound_adapter {
+	struct list_head dev_list;
+	struct most_interface *iface;
+	struct snd_card *card;
+	struct list_head list;
+	bool registered;
+	int pcm_dev_idx;
+};
+
+static struct list_head adpt_list;
+
 #define MOST_PCM_INFO (SNDRV_PCM_INFO_MMAP | \
 		       SNDRV_PCM_INFO_MMAP_VALID | \
 		       SNDRV_PCM_INFO_BATCH | \
@@ -157,9 +168,10 @@ static void most_to_alsa_copy32(void *alsa, void *most, unsigned int bytes)
 static struct channel *get_channel(struct most_interface *iface,
 				   int channel_id)
 {
+	struct sound_adapter *adpt = iface->priv;
 	struct channel *channel, *tmp;
 
-	list_for_each_entry_safe(channel, tmp, &dev_list, list) {
+	list_for_each_entry_safe(channel, tmp, &adpt->dev_list, list) {
 		if ((channel->iface == iface) && (channel->id == channel_id))
 			return channel;
 	}
@@ -460,7 +472,7 @@ static const struct snd_pcm_ops pcm_ops = {
 };
 
 static int split_arg_list(char *buf, char **card_name, u16 *ch_num,
-			  char **sample_res)
+			  char **sample_res, u8 *create)
 {
 	char *num;
 	int ret;
@@ -479,6 +491,9 @@ static int split_arg_list(char *buf, char **card_name, u16 *ch_num,
 	*sample_res = strsep(&buf, ".\n");
 	if (!*sample_res)
 		goto err;
+
+	if (buf && !strcmp(buf, "create"))
+		*create = 1;
 	return 0;
 
 err:
@@ -536,6 +551,19 @@ static int audio_set_hw_params(struct snd_pcm_hardware *pcm_hw,
 	return 0;
 }
 
+static void release_adapter(struct sound_adapter *adpt)
+{
+	struct channel *channel, *tmp;
+
+	list_for_each_entry_safe(channel, tmp, &adpt->dev_list, list) {
+		list_del(&channel->list);
+		kfree(channel);
+	}
+	snd_card_free(adpt->card);
+	list_del(&adpt->list);
+	kfree(adpt);
+}
+
 /**
  * audio_probe_channel - probe function of the driver module
  * @iface: pointer to interface instance
@@ -553,7 +581,7 @@ static int audio_probe_channel(struct most_interface *iface, int channel_id,
 			       char *arg_list)
 {
 	struct channel *channel;
-	struct snd_card *card;
+	struct sound_adapter *adpt;
 	struct snd_pcm *pcm;
 	int playback_count = 0;
 	int capture_count = 0;
@@ -561,6 +589,7 @@ static int audio_probe_channel(struct most_interface *iface, int channel_id,
 	int direction;
 	char *card_name;
 	u16 ch_num;
+	u8 create = 0;
 	char *sample_res;
 
 	if (!iface)
@@ -571,6 +600,40 @@ static int audio_probe_channel(struct most_interface *iface, int channel_id,
 		return -EINVAL;
 	}
 
+	ret = split_arg_list(arg_list, &card_name, &ch_num, &sample_res,
+			     &create);
+	if (ret < 0)
+		return ret;
+
+	list_for_each_entry(adpt, &adpt_list, list) {
+		if (adpt->iface == iface && adpt->registered)
+			return -ENOSPC;
+		if (!adpt->registered) {
+			adpt->pcm_dev_idx++;
+			goto skip_adpt_alloc;
+		}
+	}
+	adpt = kzalloc(sizeof(*adpt), GFP_KERNEL);
+	if (!adpt)
+		return -ENOMEM;
+
+	adpt->iface = iface;
+	adpt->registered = false;
+	adpt->pcm_dev_idx = 0;
+	INIT_LIST_HEAD(&adpt->dev_list);
+	iface->priv = adpt;
+	ret = snd_card_new(&iface->dev, -1, card_name, THIS_MODULE,
+			   sizeof(*channel), &adpt->card);
+	if (ret < 0)
+		return ret;
+	snprintf(adpt->card->driver, sizeof(adpt->card->driver),
+		 "%s", DRIVER_NAME);
+	snprintf(adpt->card->shortname, sizeof(adpt->card->shortname),
+		 "Microchip MOST:%d", adpt->card->number);
+	snprintf(adpt->card->longname, sizeof(adpt->card->longname),
+		 "%s at %s, ch %d", adpt->card->shortname, iface->description,
+		 channel_id);
+skip_adpt_alloc:
 	if (get_channel(iface, channel_id)) {
 		pr_err("channel (%s:%d) is already linked\n",
 		       iface->description, channel_id);
@@ -584,36 +647,25 @@ static int audio_probe_channel(struct most_interface *iface, int channel_id,
 		capture_count = 1;
 		direction = SNDRV_PCM_STREAM_CAPTURE;
 	}
-
-	ret = split_arg_list(arg_list, &card_name, &ch_num, &sample_res);
-	if (ret < 0)
-		return ret;
-
-	ret = snd_card_new(&iface->dev, -1, card_name, THIS_MODULE,
-			   sizeof(*channel), &card);
-	if (ret < 0)
-		return ret;
-
-	channel = card->private_data;
-	channel->card = card;
+	channel = kzalloc(sizeof(*channel), GFP_KERNEL);
+	if (!channel)
+		goto err_free_card;
+	channel->card = adpt->card;
 	channel->cfg = cfg;
 	channel->iface = iface;
 	channel->id = channel_id;
 	init_waitqueue_head(&channel->playback_waitq);
+	list_add_tail(&channel->list, &adpt->dev_list);
+	list_add_tail(&adpt->list, &adpt_list);
 
 	ret = audio_set_hw_params(&channel->pcm_hardware, ch_num, sample_res,
 				  cfg);
 	if (ret)
 		goto err_free_card;
 
-	snprintf(card->driver, sizeof(card->driver), "%s", DRIVER_NAME);
-	snprintf(card->shortname, sizeof(card->shortname), "Microchip MOST:%d",
-		 card->number);
-	snprintf(card->longname, sizeof(card->longname), "%s at %s, ch %d",
-		 card->shortname, iface->description, channel_id);
+	ret = snd_pcm_new(adpt->card, card_name, adpt->pcm_dev_idx,
+			  playback_count, capture_count, &pcm);
 
-	ret = snd_pcm_new(card, card_name, 0, playback_count,
-			  capture_count, &pcm);
 	if (ret < 0)
 		goto err_free_card;
 
@@ -621,16 +673,16 @@ static int audio_probe_channel(struct most_interface *iface, int channel_id,
 
 	snd_pcm_set_ops(pcm, direction, &pcm_ops);
 
-	ret = snd_card_register(card);
-	if (ret < 0)
-		goto err_free_card;
-
-	list_add_tail(&channel->list, &dev_list);
-
+	if (create) {
+		ret = snd_card_register(adpt->card);
+		if (ret < 0)
+			goto err_free_card;
+		adpt->registered = true;
+	}
 	return 0;
 
 err_free_card:
-	snd_card_free(card);
+	release_adapter(adpt);
 	return ret;
 }
 
@@ -647,6 +699,7 @@ static int audio_disconnect_channel(struct most_interface *iface,
 				    int channel_id)
 {
 	struct channel *channel;
+	struct sound_adapter *adpt = iface->priv;
 
 	channel = get_channel(iface, channel_id);
 	if (!channel) {
@@ -656,8 +709,10 @@ static int audio_disconnect_channel(struct most_interface *iface,
 	}
 
 	list_del(&channel->list);
-	snd_card_free(channel->card);
 
+	kfree(channel);
+	if (list_empty(&adpt->dev_list))
+		release_adapter(adpt);
 	return 0;
 }
 
@@ -733,22 +788,14 @@ static int __init audio_init(void)
 {
 	pr_info("init()\n");
 
-	INIT_LIST_HEAD(&dev_list);
+	INIT_LIST_HEAD(&adpt_list);
 
 	return most_register_component(&comp);
 }
 
 static void __exit audio_exit(void)
 {
-	struct channel *channel, *tmp;
-
 	pr_info("exit()\n");
-
-	list_for_each_entry_safe(channel, tmp, &dev_list, list) {
-		list_del(&channel->list);
-		snd_card_free(channel->card);
-	}
-
 	most_deregister_component(&comp);
 }
 
-- 
2.7.4

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