ALSA: PCM: channel mapping API implementation
This patch implements the basic data types for the standard channel
mapping API handling.
- The definitions of the channel positions and the new TLV types are
added in sound/asound.h and sound/tlv.h, so that they can be
referred from user-space.
- Introduced a new helper function snd_pcm_add_chmap_ctls() to create
control elements representing the channel maps for each PCM
(sub)stream.
- Some standard pre-defined channel maps are provided for
convenience.
Signed-off-by: Takashi Iwai <tiwai@suse.de>
diff --git a/sound/core/pcm_lib.c b/sound/core/pcm_lib.c
index 7ae6719..5651027 100644
--- a/sound/core/pcm_lib.c
+++ b/sound/core/pcm_lib.c
@@ -26,6 +26,7 @@
#include <linux/export.h>
#include <sound/core.h>
#include <sound/control.h>
+#include <sound/tlv.h>
#include <sound/info.h>
#include <sound/pcm.h>
#include <sound/pcm_params.h>
@@ -2302,3 +2303,217 @@
}
EXPORT_SYMBOL(snd_pcm_lib_readv);
+
+/*
+ * standard channel mapping helpers
+ */
+
+/* default channel maps for multi-channel playbacks, up to 8 channels */
+const struct snd_pcm_chmap_elem snd_pcm_std_chmaps[] = {
+ { .channels = 1,
+ .map = { SNDRV_CHMAP_FC } },
+ { .channels = 2,
+ .map = { SNDRV_CHMAP_FL, SNDRV_CHMAP_FR } },
+ { .channels = 4,
+ .map = { SNDRV_CHMAP_FL, SNDRV_CHMAP_FR,
+ SNDRV_CHMAP_RL, SNDRV_CHMAP_RR } },
+ { .channels = 6,
+ .map = { SNDRV_CHMAP_FL, SNDRV_CHMAP_FR,
+ SNDRV_CHMAP_RL, SNDRV_CHMAP_RR,
+ SNDRV_CHMAP_FC, SNDRV_CHMAP_LFE } },
+ { .channels = 8,
+ .map = { SNDRV_CHMAP_FL, SNDRV_CHMAP_FR,
+ SNDRV_CHMAP_RL, SNDRV_CHMAP_RR,
+ SNDRV_CHMAP_FC, SNDRV_CHMAP_LFE,
+ SNDRV_CHMAP_SL, SNDRV_CHMAP_SR } },
+ { }
+};
+EXPORT_SYMBOL_GPL(snd_pcm_std_chmaps);
+
+/* alternative channel maps with CLFE <-> surround swapped for 6/8 channels */
+const struct snd_pcm_chmap_elem snd_pcm_alt_chmaps[] = {
+ { .channels = 1,
+ .map = { SNDRV_CHMAP_FC } },
+ { .channels = 2,
+ .map = { SNDRV_CHMAP_FL, SNDRV_CHMAP_FR } },
+ { .channels = 4,
+ .map = { SNDRV_CHMAP_FL, SNDRV_CHMAP_FR,
+ SNDRV_CHMAP_RL, SNDRV_CHMAP_RR } },
+ { .channels = 6,
+ .map = { SNDRV_CHMAP_FL, SNDRV_CHMAP_FR,
+ SNDRV_CHMAP_FC, SNDRV_CHMAP_LFE,
+ SNDRV_CHMAP_RL, SNDRV_CHMAP_RR } },
+ { .channels = 8,
+ .map = { SNDRV_CHMAP_FL, SNDRV_CHMAP_FR,
+ SNDRV_CHMAP_FC, SNDRV_CHMAP_LFE,
+ SNDRV_CHMAP_RL, SNDRV_CHMAP_RR,
+ SNDRV_CHMAP_SL, SNDRV_CHMAP_SR } },
+ { }
+};
+EXPORT_SYMBOL_GPL(snd_pcm_alt_chmaps);
+
+static bool valid_chmap_channels(const struct snd_pcm_chmap *info, int ch)
+{
+ if (ch > info->max_channels)
+ return false;
+ return !info->channel_mask || (info->channel_mask & (1U << ch));
+}
+
+static int pcm_chmap_ctl_info(struct snd_kcontrol *kcontrol,
+ struct snd_ctl_elem_info *uinfo)
+{
+ struct snd_pcm_chmap *info = snd_kcontrol_chip(kcontrol);
+
+ uinfo->type = SNDRV_CTL_ELEM_TYPE_INTEGER;
+ uinfo->count = 0;
+ uinfo->count = info->max_channels;
+ uinfo->value.integer.min = 0;
+ uinfo->value.integer.max = SNDRV_CHMAP_LAST;
+ return 0;
+}
+
+/* get callback for channel map ctl element
+ * stores the channel position firstly matching with the current channels
+ */
+static int pcm_chmap_ctl_get(struct snd_kcontrol *kcontrol,
+ struct snd_ctl_elem_value *ucontrol)
+{
+ struct snd_pcm_chmap *info = snd_kcontrol_chip(kcontrol);
+ unsigned int idx = snd_ctl_get_ioffidx(kcontrol, &ucontrol->id);
+ struct snd_pcm_substream *substream;
+ const struct snd_pcm_chmap_elem *map;
+
+ if (snd_BUG_ON(!info->chmap))
+ return -EINVAL;
+ substream = snd_pcm_chmap_substream(info, idx);
+ if (!substream)
+ return -ENODEV;
+ memset(ucontrol->value.integer.value, 0,
+ sizeof(ucontrol->value.integer.value));
+ if (!substream->runtime)
+ return 0; /* no channels set */
+ for (map = info->chmap; map->channels; map++) {
+ int i;
+ if (map->channels == substream->runtime->channels &&
+ valid_chmap_channels(info, map->channels)) {
+ for (i = 0; i < map->channels; i++)
+ ucontrol->value.integer.value[i] = map->map[i];
+ return 0;
+ }
+ }
+ return -EINVAL;
+}
+
+/* tlv callback for channel map ctl element
+ * expands the pre-defined channel maps in a form of TLV
+ */
+static int pcm_chmap_ctl_tlv(struct snd_kcontrol *kcontrol, int op_flag,
+ unsigned int size, unsigned int __user *tlv)
+{
+ struct snd_pcm_chmap *info = snd_kcontrol_chip(kcontrol);
+ const struct snd_pcm_chmap_elem *map;
+ unsigned int __user *dst;
+ int c, count = 0;
+
+ if (snd_BUG_ON(!info->chmap))
+ return -EINVAL;
+ if (size < 8)
+ return -ENOMEM;
+ if (put_user(SNDRV_CTL_TLVT_CONTAINER, tlv))
+ return -EFAULT;
+ size -= 8;
+ dst = tlv + 2;
+ for (map = info->chmap; map->channels; map++) {
+ int chs_bytes = map->channels * 4;
+ if (!valid_chmap_channels(info, map->channels))
+ continue;
+ if (size < 8)
+ return -ENOMEM;
+ if (put_user(SNDRV_CTL_TLVT_CHMAP_FIXED, dst) ||
+ put_user(chs_bytes, dst + 1))
+ return -EFAULT;
+ dst += 2;
+ size -= 8;
+ count += 8;
+ if (size < chs_bytes)
+ return -ENOMEM;
+ size -= chs_bytes;
+ count += chs_bytes;
+ for (c = 0; c < map->channels; c++) {
+ if (put_user(map->map[c], dst))
+ return -EFAULT;
+ dst++;
+ }
+ }
+ if (put_user(count, tlv + 1))
+ return -EFAULT;
+ return 0;
+}
+
+static void pcm_chmap_ctl_private_free(struct snd_kcontrol *kcontrol)
+{
+ struct snd_pcm_chmap *info = snd_kcontrol_chip(kcontrol);
+ info->pcm->streams[info->stream].chmap_kctl = NULL;
+ kfree(info);
+}
+
+/**
+ * snd_pcm_add_chmap_ctls - create channel-mapping control elements
+ * @pcm: the assigned PCM instance
+ * @stream: stream direction
+ * @chmap: channel map elements (for query)
+ * @max_channels: the max number of channels for the stream
+ * @private_value: the value passed to each kcontrol's private_value field
+ * @info_ret: store struct snd_pcm_chmap instance if non-NULL
+ *
+ * Create channel-mapping control elements assigned to the given PCM stream(s).
+ * Returns zero if succeed, or a negative error value.
+ */
+int snd_pcm_add_chmap_ctls(struct snd_pcm *pcm, int stream,
+ const struct snd_pcm_chmap_elem *chmap,
+ int max_channels,
+ unsigned long private_value,
+ struct snd_pcm_chmap **info_ret)
+{
+ struct snd_pcm_chmap *info;
+ struct snd_kcontrol_new knew = {
+ .iface = SNDRV_CTL_ELEM_IFACE_PCM,
+ .access = SNDRV_CTL_ELEM_ACCESS_READ |
+ SNDRV_CTL_ELEM_ACCESS_VOLATILE | /* no notification */
+ SNDRV_CTL_ELEM_ACCESS_TLV_READ |
+ SNDRV_CTL_ELEM_ACCESS_TLV_CALLBACK,
+ .info = pcm_chmap_ctl_info,
+ .get = pcm_chmap_ctl_get,
+ .tlv.c = pcm_chmap_ctl_tlv,
+ };
+ int err;
+
+ info = kzalloc(sizeof(*info), GFP_KERNEL);
+ if (!info)
+ return -ENOMEM;
+ info->pcm = pcm;
+ info->stream = stream;
+ info->chmap = chmap;
+ info->max_channels = max_channels;
+ if (stream == SNDRV_PCM_STREAM_PLAYBACK)
+ knew.name = "Playback Channel Map";
+ else
+ knew.name = "Capture Channel Map";
+ 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);
+ return -ENOMEM;
+ }
+ info->kctl->private_free = pcm_chmap_ctl_private_free;
+ err = snd_ctl_add(pcm->card, info->kctl);
+ if (err < 0)
+ return err;
+ pcm->streams[stream].chmap_kctl = info->kctl;
+ if (info_ret)
+ *info_ret = info;
+ return 0;
+}
+EXPORT_SYMBOL_GPL(snd_pcm_add_chmap_ctls);