The layer registration allows to handle an extra functionality
on top of the control API. It can be used for the audio
LED control for example.
Signed-off-by: Jaroslav Kysela <perex@xxxxxxxx>
---
include/sound/control.h | 12 +++++
sound/core/control.c | 104 +++++++++++++++++++++++++++++++++++++++-
2 files changed, 114 insertions(+), 2 deletions(-)
diff --git a/include/sound/control.h b/include/sound/control.h
index 22f3d48163ff..175610bfa8c8 100644
--- a/include/sound/control.h
+++ b/include/sound/control.h
@@ -108,6 +108,14 @@ struct snd_ctl_file {
struct list_head events; /* waiting events for read */
};
+struct snd_ctl_layer_ops {
+ struct snd_ctl_layer_ops *next;
+ const char *module_name;
+ void (*lregister)(struct snd_card *card);
+ void (*ldisconnect)(struct snd_card *card);
+ void (*lnotify)(struct snd_card *card, unsigned int mask, struct snd_kcontrol *kctl, unsigned int ioff);
+};
+
#define snd_ctl_file(n) list_entry(n, struct snd_ctl_file, list)
typedef int (*snd_kctl_ioctl_func_t) (struct snd_card * card,
@@ -140,6 +148,10 @@ int snd_ctl_unregister_ioctl_compat(snd_kctl_ioctl_func_t fcn);
#define snd_ctl_unregister_ioctl_compat(fcn)
#endif
+int snd_ctl_request_layer(const char *module_name);
+void snd_ctl_register_layer(struct snd_ctl_layer_ops *lops);
+void snd_ctl_disconnect_layer(struct snd_ctl_layer_ops *lops);
+
int snd_ctl_get_preferred_subdevice(struct snd_card *card, int type);
static inline unsigned int snd_ctl_get_ioffnum(struct snd_kcontrol *kctl, struct snd_ctl_elem_id *id)
diff --git a/sound/core/control.c b/sound/core/control.c
index 8a5cedb0a4be..19aa19d8ff92 100644
--- a/sound/core/control.c
+++ b/sound/core/control.c
@@ -28,10 +28,12 @@ struct snd_kctl_ioctl {
};
static DECLARE_RWSEM(snd_ioctl_rwsem);
+static DECLARE_RWSEM(snd_ctl_layer_rwsem);
static LIST_HEAD(snd_control_ioctls);
#ifdef CONFIG_COMPAT
static LIST_HEAD(snd_control_compat_ioctls);
#endif
+static struct snd_ctl_layer_ops *snd_ctl_layer;
static int snd_ctl_open(struct inode *inode, struct file *file)
{
@@ -195,10 +197,15 @@ void snd_ctl_notify_one(struct snd_card *card, unsigned int mask,
struct snd_kcontrol *kctl, unsigned int ioff)
{
struct snd_ctl_elem_id id = kctl->id;
+ struct snd_ctl_layer_ops *lops;
id.index += ioff;
id.numid += ioff;
snd_ctl_notify(card, mask, &id);
+ down_read(&snd_ctl_layer_rwsem);
+ for (lops = snd_ctl_layer; lops; lops = lops->next)
+ lops->lnotify(card, mask, kctl, ioff);
+ up_read(&snd_ctl_layer_rwsem);
}
EXPORT_SYMBOL(snd_ctl_notify_one);
@@ -1997,6 +2004,84 @@ EXPORT_SYMBOL_GPL(snd_ctl_get_preferred_subdevice);
#define snd_ctl_ioctl_compat NULL
#endif
+/*
+ * control layers (audio LED etc.)
+ */
+
+/**
+ * snd_ctl_request_layer - request to use the layer
+ * @module_name: Name of the kernel module (NULL == build-in)
+ *
+ * Return an error code when the module cannot be loaded.
+ */
+int snd_ctl_request_layer(const char *module_name)
+{
+ struct snd_ctl_layer_ops *lops;
+
+ if (module_name == NULL)
+ return 0;
+ down_read(&snd_ctl_layer_rwsem);
+ for (lops = snd_ctl_layer; lops; lops = lops->next)
+ if (strcmp(lops->module_name, module_name) == 0)
+ break;
+ up_read(&snd_ctl_layer_rwsem);
+ if (lops)
+ return 0;
+ return request_module(module_name);
+}
+EXPORT_SYMBOL_GPL(snd_ctl_request_layer);
+
+/**
+ * snd_ctl_register_layer - register new control layer
+ * @lops: operation structure
+ *
+ * The new layer can track all control elements and do additional
+ * operations on top (like audio LED handling).
+ */
+void snd_ctl_register_layer(struct snd_ctl_layer_ops *lops)
+{
+ struct snd_card *card;
+ int card_number;
+
+ down_write(&snd_ctl_layer_rwsem);
+ lops->next = snd_ctl_layer;
+ snd_ctl_layer = lops;
+ for (card_number = 0; card_number < SNDRV_CARDS; card_number++) {
+ card = snd_card_ref(card_number);
+ if (card) {
+ lops->lregister(card);
+ snd_card_unref(card);
+ }
+ }
+ up_write(&snd_ctl_layer_rwsem);
+}
+EXPORT_SYMBOL_GPL(snd_ctl_register_layer);
+
+/**
+ * snd_ctl_disconnect_layer - disconnect control layer
+ * @lops: operation structure
+ *
+ * It is expected that the information about tracked cards
+ * is freed before this call (the disconnect callback is
+ * not called here).
+ */
+void snd_ctl_disconnect_layer(struct snd_ctl_layer_ops *lops)
+{
+ struct snd_ctl_layer_ops *lops2, *prev_lops2;
+
+ down_write(&snd_ctl_layer_rwsem);
+ for (lops2 = snd_ctl_layer, prev_lops2 = NULL; lops2; lops2 = lops2->next)
+ if (lops2 == lops) {
+ if (!prev_lops2)
+ snd_ctl_layer = lops->next;
+ else
+ prev_lops2->next = lops->next;
+ break;
+ }
+ up_write(&snd_ctl_layer_rwsem);
+}
+EXPORT_SYMBOL_GPL(snd_ctl_disconnect_layer);
+
/*
* INIT PART
*/
@@ -2020,9 +2105,18 @@ static const struct file_operations snd_ctl_f_ops =
static int snd_ctl_dev_register(struct snd_device *device)
{
struct snd_card *card = device->device_data;
+ struct snd_ctl_layer_ops *lops;
+ int err;
- return snd_register_device(SNDRV_DEVICE_TYPE_CONTROL, card, -1,
- &snd_ctl_f_ops, card, &card->ctl_dev);
+ err = snd_register_device(SNDRV_DEVICE_TYPE_CONTROL, card, -1,
+ &snd_ctl_f_ops, card, &card->ctl_dev);
+ if (err < 0)
+ return err;
+ down_read(&snd_ctl_layer_rwsem);
+ for (lops = snd_ctl_layer; lops; lops = lops->next)
+ lops->lregister(card);
+ up_read(&snd_ctl_layer_rwsem);
+ return 0;
}
/*
@@ -2032,6 +2126,7 @@ static int snd_ctl_dev_disconnect(struct snd_device *device)
{
struct snd_card *card = device->device_data;
struct snd_ctl_file *ctl;
+ struct snd_ctl_layer_ops *lops;
unsigned long flags;
read_lock_irqsave(&card->ctl_files_rwlock, flags);
@@ -2041,6 +2136,11 @@ static int snd_ctl_dev_disconnect(struct snd_device *device)
}
read_unlock_irqrestore(&card->ctl_files_rwlock, flags);
+ down_read(&snd_ctl_layer_rwsem);
+ for (lops = snd_ctl_layer; lops; lops = lops->next)
+ lops->ldisconnect(card);
+ up_read(&snd_ctl_layer_rwsem);
+
return snd_unregister_device(&card->ctl_dev);
}
--
2.29.2
