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@perex.cz --- include/sound/control.h | 12 +++++ sound/core/control.c | 110 +++++++++++++++++++++++++++++++++++++++- 2 files changed, 120 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..87630021e434 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 +2004,86 @@ 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; + up_write(&snd_ctl_layer_rwsem); + for (card_number = 0; card_number < SNDRV_CARDS; card_number++) { + card = snd_card_ref(card_number); + if (card) { + down_read(&card->controls_rwsem); + lops->lregister(card); + up_read(&card->controls_rwsem); + snd_card_unref(card); + } + } +} +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 +2107,20 @@ 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(&card->controls_rwsem); + down_read(&snd_ctl_layer_rwsem); + for (lops = snd_ctl_layer; lops; lops = lops->next) + lops->lregister(card); + up_read(&snd_ctl_layer_rwsem); + up_read(&card->controls_rwsem); + return 0; }
/* @@ -2032,6 +2130,7 @@ 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 +2140,13 @@ static int snd_ctl_dev_disconnect(struct snd_device *device) } read_unlock_irqrestore(&card->ctl_files_rwlock, flags);
+ down_read(&card->controls_rwsem); + down_read(&snd_ctl_layer_rwsem); + for (lops = snd_ctl_layer; lops; lops = lops->next) + lops->ldisconnect(card); + up_read(&snd_ctl_layer_rwsem); + up_read(&card->controls_rwsem); + return snd_unregister_device(&card->ctl_dev); }