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-rw-r--r--sound/core/vmaster.c46
1 files changed, 45 insertions, 1 deletions
diff --git a/sound/core/vmaster.c b/sound/core/vmaster.c
index 130cfe677d60..14a286a7bf2b 100644
--- a/sound/core/vmaster.c
+++ b/sound/core/vmaster.c
@@ -37,6 +37,8 @@ struct link_master {
struct link_ctl_info info;
int val; /* the master value */
unsigned int tlv[4];
+ void (*hook)(void *private_data, int);
+ void *hook_private_data;
};
/*
@@ -126,7 +128,9 @@ static int master_init(struct link_master *master)
master->info.count = 1; /* always mono */
/* set full volume as default (= no attenuation) */
master->val = master->info.max_val;
- return 0;
+ if (master->hook)
+ master->hook(master->hook_private_data, master->val);
+ return 1;
}
return -ENOENT;
}
@@ -329,6 +333,8 @@ static int master_put(struct snd_kcontrol *kcontrol,
slave_put_val(slave, uval);
}
kfree(uval);
+ if (master->hook && !err)
+ master->hook(master->hook_private_data, master->val);
return 1;
}
@@ -408,3 +414,41 @@ struct snd_kcontrol *snd_ctl_make_virtual_master(char *name,
return kctl;
}
EXPORT_SYMBOL(snd_ctl_make_virtual_master);
+
+/**
+ * snd_ctl_add_vmaster_hook - Add a hook to a vmaster control
+ * @kcontrol: vmaster kctl element
+ * @hook: the hook function
+ *
+ * Adds the given hook to the vmaster control element so that it's called
+ * at each time when the value is changed.
+ */
+int snd_ctl_add_vmaster_hook(struct snd_kcontrol *kcontrol,
+ void (*hook)(void *private_data, int),
+ void *private_data)
+{
+ struct link_master *master = snd_kcontrol_chip(kcontrol);
+ master->hook = hook;
+ master->hook_private_data = private_data;
+ return 0;
+}
+EXPORT_SYMBOL_GPL(snd_ctl_add_vmaster_hook);
+
+/**
+ * snd_ctl_sync_vmaster_hook - Sync the vmaster hook
+ * @kcontrol: vmaster kctl element
+ *
+ * Call the hook function to synchronize with the current value of the given
+ * vmaster element. NOP when NULL is passed to @kcontrol or the hook doesn't
+ * exist.
+ */
+void snd_ctl_sync_vmaster_hook(struct snd_kcontrol *kcontrol)
+{
+ struct link_master *master;
+ if (!kcontrol)
+ return;
+ master = snd_kcontrol_chip(kcontrol);
+ if (master->hook)
+ master->hook(master->hook_private_data, master->val);
+}
+EXPORT_SYMBOL_GPL(snd_ctl_sync_vmaster_hook);