[RFC PATCH 04/11] ALSA: implement MEDIA_IOC_ENUM_LINKS (1)

[Clemens Ladisch <clemens@ladisch.de>]

Allow to retrieve pad information.

Signed-off-by: Clemens Ladisch <clemens@ladisch.de>
---
 sound/core/media.c |   44 ++++++++++++++++++++++++++++++++++++++++++++
 1 files changed, 44 insertions(+), 0 deletions(-)

diff --git a/sound/core/media.c b/sound/core/media.c
index aa94175..96b09a3 100644
--- a/sound/core/media.c
+++ b/sound/core/media.c
@@ -161,6 +161,48 @@ static int snd_media_enum_entities(struct snd_card *card,
 	return copy_to_user(descp, &desc, sizeof(desc));
 }

+static int snd_media_enum_links(struct snd_card *card,
+				struct media_links_enum __user *linksp)
+{
+	struct media_links_enum links;
+	struct snd_media_entity *entity;
+
+	if (copy_from_user(&links, linksp, sizeof(links)))
+		return -EFAULT;
+
+	mutex_lock(&card->media_mutex);
+	entity = search_entity(card, links.entity);
+	mutex_unlock(&card->media_mutex);
+	if (!entity)
+		return -EINVAL;
+
+	if (links.pads) {
+		struct media_pad_desc pad;
+		unsigned int i;
+
+		memset(&pad, 0, sizeof(pad));
+		pad.entity = entity->id;
+
+		pad.flags = MEDIA_PAD_FL_SINK;
+		for (i = 0; i < entity->sinks; i++) {
+			if (copy_to_user(links.pads, &pad, sizeof(pad)))
+				return -EFAULT;
+			links.pads++;
+			pad.index++;
+		}
+
+		pad.flags = MEDIA_PAD_FL_SOURCE;
+		for (i = 0; i < entity->sources; i++) {
+			if (copy_to_user(links.pads, &pad, sizeof(pad)))
+				return -EFAULT;
+			links.pads++;
+			pad.index++;
+		}
+	}
+
+	return 0;
+}
+
 static int snd_media_control_ioctl(struct snd_card *card,
 				   struct snd_ctl_file *ctl_file,
 				   unsigned int cmd, unsigned long arg)
@@ -172,6 +214,8 @@ static int snd_media_control_ioctl(struct snd_card *card,
 		return snd_media_device_info(card, argp);
 	case MEDIA_IOC_ENUM_ENTITIES:
 		return snd_media_enum_entities(card, argp);
+	case MEDIA_IOC_ENUM_LINKS:
+		return snd_media_enum_links(card, argp);
 	default:
 		return -ENOIOCTLCMD;
 	}