ALSA: Add a hook capability to vmaster controls
This patch adds a hook to vmaster control to be called at each time
when the master value is changed. It'd be handy for an additional
mute LED control following the Master switch, for example.
Signed-off-by: Takashi Iwai <tiwai@suse.de>
diff --git a/sound/core/vmaster.c b/sound/core/vmaster.c
index 130cfe6..14a286a 100644
--- a/sound/core/vmaster.c
+++ b/sound/core/vmaster.c
@@ -37,6 +37,8 @@
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 @@
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 @@
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 @@
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);