ALSA: PCM: volume API implementation
Introduced a new helper function snd_pcm_add_volume_ctls() to
create control elements representing the volume for each PCM
(sub)stream.
Change-Id: Id483257c4fe84a909e7a4af3a5aa3e4f0d5d9ea5
Signed-off-by: Damir Didjusto <damird@codeaurora.org>
diff --git a/include/sound/pcm.h b/include/sound/pcm.h
index 028e683..8984405 100644
--- a/include/sound/pcm.h
+++ b/include/sound/pcm.h
@@ -447,6 +447,7 @@
#endif
#endif
struct snd_kcontrol *chmap_kctl; /* channel-mapping controls */
+ struct snd_kcontrol *vol_kctl; /* volume controls */
};
struct snd_pcm {
@@ -1128,4 +1129,28 @@
unsigned long private_value,
struct snd_pcm_chmap **info_ret);
+/*
+ * PCM Volume control API
+ */
+/* array element of volume */
+struct snd_pcm_volume_elem {
+ int volume;
+};
+
+/* pp information; retrieved via snd_kcontrol_chip() */
+struct snd_pcm_volume {
+ struct snd_pcm *pcm; /* assigned PCM instance */
+ int stream; /* PLAYBACK or CAPTURE */
+ struct snd_kcontrol *kctl;
+ const struct snd_pcm_volume_elem *volume;
+ int max_length;
+ void *private_data; /* optional: private data pointer */
+};
+
+int snd_pcm_add_volume_ctls(struct snd_pcm *pcm, int stream,
+ const struct snd_pcm_volume_elem *volume,
+ int max_length,
+ unsigned long private_value,
+ struct snd_pcm_volume **info_ret);
+
#endif /* __SOUND_PCM_H */
diff --git a/sound/core/pcm.c b/sound/core/pcm.c
index d98e160..2e8d6f4 100644
--- a/sound/core/pcm.c
+++ b/sound/core/pcm.c
@@ -1199,6 +1199,10 @@
snd_ctl_remove(pcm->card, pcm->streams[cidx].chmap_kctl);
pcm->streams[cidx].chmap_kctl = NULL;
}
+ if (pcm->streams[cidx].vol_kctl) {
+ snd_ctl_remove(pcm->card, pcm->streams[cidx].vol_kctl);
+ pcm->streams[cidx].vol_kctl = NULL;
+ }
}
unlock:
mutex_unlock(®ister_mutex);
diff --git a/sound/core/pcm_lib.c b/sound/core/pcm_lib.c
index e0ab899..06d617b 100644
--- a/sound/core/pcm_lib.c
+++ b/sound/core/pcm_lib.c
@@ -31,6 +31,8 @@
#include <sound/pcm_params.h>
#include <sound/timer.h>
+#define STRING_LENGTH_OF_INT 12
+
/*
* fill ring buffer with silence
* runtime->silence_start: starting pointer to silence area
@@ -2444,6 +2446,23 @@
kfree(info);
}
+static int pcm_volume_ctl_info(struct snd_kcontrol *kcontrol,
+ struct snd_ctl_elem_info *uinfo)
+{
+ uinfo->type = SNDRV_CTL_ELEM_TYPE_INTEGER;
+ uinfo->count = 1;
+ uinfo->value.integer.min = 0;
+ uinfo->value.integer.max = 0x2000;
+ return 0;
+}
+
+static void pcm_volume_ctl_private_free(struct snd_kcontrol *kcontrol)
+{
+ struct snd_pcm_volume *info = snd_kcontrol_chip(kcontrol);
+ info->pcm->streams[info->stream].vol_kctl = NULL;
+ kfree(info);
+}
+
/**
* snd_pcm_add_chmap_ctls - create channel-mapping control elements
* @pcm: the assigned PCM instance
@@ -2503,3 +2522,74 @@
return 0;
}
EXPORT_SYMBOL_GPL(snd_pcm_add_chmap_ctls);
+
+/**
+ * snd_pcm_add_volume_ctls - create volume control elements
+ * @pcm: the assigned PCM instance
+ * @stream: stream direction
+ * @max_length: the max length of the volume parameter of stream
+ * @private_value: the value passed to each kcontrol's private_value field
+ * @info_ret: store struct snd_pcm_volume instance if non-NULL
+ *
+ * Create volume control elements assigned to the given PCM stream(s).
+ * Returns zero if succeed, or a negative error value.
+ */
+int snd_pcm_add_volume_ctls(struct snd_pcm *pcm, int stream,
+ const struct snd_pcm_volume_elem *volume,
+ int max_length,
+ unsigned long private_value,
+ struct snd_pcm_volume **info_ret)
+{
+ struct snd_pcm_volume *info;
+ struct snd_kcontrol_new knew = {
+ .iface = SNDRV_CTL_ELEM_IFACE_MIXER,
+ .access = SNDRV_CTL_ELEM_ACCESS_TLV_READ |
+ SNDRV_CTL_ELEM_ACCESS_READWRITE,
+ .info = pcm_volume_ctl_info,
+ };
+ int err;
+ int size;
+
+ info = kzalloc(sizeof(*info), GFP_KERNEL);
+ if (!info)
+ return -ENOMEM;
+ info->pcm = pcm;
+ info->stream = stream;
+ info->volume = volume;
+ info->max_length = max_length;
+ size = sizeof("Playback ") + sizeof(" Volume") +
+ STRING_LENGTH_OF_INT*sizeof(char) + 1;
+ knew.name = kzalloc(size, GFP_KERNEL);
+ if (!knew.name) {
+ kfree(info);
+ return -ENOMEM;
+ }
+ if (stream == SNDRV_PCM_STREAM_PLAYBACK)
+ snprintf(knew.name, size, "%s %d %s",
+ "Playback", pcm->device, "Volume");
+ else
+ snprintf(knew.name, size, "%s %d %s",
+ "Capture", pcm->device, "Volume");
+ knew.device = pcm->device;
+ knew.count = pcm->streams[stream].substream_count;
+ knew.private_value = private_value;
+ info->kctl = snd_ctl_new1(&knew, info);
+ if (!info->kctl) {
+ kfree(info);
+ kfree(knew.name);
+ return -ENOMEM;
+ }
+ info->kctl->private_free = pcm_volume_ctl_private_free;
+ err = snd_ctl_add(pcm->card, info->kctl);
+ if (err < 0) {
+ kfree(info);
+ kfree(knew.name);
+ return -ENOMEM;
+ }
+ pcm->streams[stream].vol_kctl = info->kctl;
+ if (info_ret)
+ *info_ret = info;
+ kfree(knew.name);
+ return 0;
+}
+EXPORT_SYMBOL_GPL(snd_pcm_add_volume_ctls);