[very-RFC 7/8] AVB ALSA - Add ALSA shim for TSN

Henrik Austad
2016-06-11T23:01:45Z

From: Henrik Austad <haustad@cisco.com>

This exposes a *very* rudimentary and simplistic ALSA driver that hooks
into TSN to create a device for userspace.

It currently only supports 44.1/48kHz sampling, 2ch, S16_LE

Userspace is supposed to reserve bandwidth, find StreamID etc.

To use as a Talker:

mkdir /config/tsn/test/eth0/talker
cd /config/tsn/test/eth0/talker
echo 65535 > buffer_size
echo 08:00:27:08:9f:c3 > remote_mac
echo 42 > stream_id
echo alsa > enabled

aplay -Ddefault:CARD=avb -c2 -r48000 -fS16_LE /opt/rickroll.wav

The same applies to Listener and arecord.

Cc: Mauro Carvalho Chehab <mchehab@osg.samsung.com>
Cc: Takashi Iwai <tiwai@suse.de>
Cc: Mark Brown <broonie@kernel.org>
Signed-off-by: Henrik Austad <haustad@cisco.com>
---
drivers/media/Kconfig | 15 +
drivers/media/Makefile | 3 +-
drivers/media/avb/Makefile | 5 +
drivers/media/avb/avb_alsa.c | 742 +++++++++++++++++++++++++++++++++++++++
drivers/media/avb/tsn_iec61883.h | 124 +++++++
5 files changed, 888 insertions(+), 1 deletion(-)
create mode 100644 drivers/media/avb/Makefile
create mode 100644 drivers/media/avb/avb_alsa.c
create mode 100644 drivers/media/avb/tsn_iec61883.h

diff --git a/drivers/media/Kconfig b/drivers/media/Kconfig
index a8518fb..14ad1d9 100644
--- a/drivers/media/Kconfig
+++ b/drivers/media/Kconfig
@@ -217,3 +217,18 @@ source "drivers/media/tuners/Kconfig"
source "drivers/media/dvb-frontends/Kconfig"

endif # MEDIA_SUPPORT
+
+config MEDIA_AVB_ALSA
+ tristate "ALSA part of AVB over TSN"
+ depends on TSN
+ help
+
+ Enable the ALSA device that hoooks into TSN and allows the
+ computer to send ethernet frames over the network carrying
+ audio-data to selected hosts.
+
+ This must be configured by userspace as MSRP and IEEE 1722.1
+ (discovery and enumeration) is not implemented within the
+ kernel.
+
+ If unsure, say N
\ No newline at end of file
diff --git a/drivers/media/Makefile b/drivers/media/Makefile
index e608bbc..a1ca09e 100644
--- a/drivers/media/Makefile
+++ b/drivers/media/Makefile
@@ -20,6 +20,7 @@ endif

obj-$(CONFIG_VIDEO_DEV) += v4l2-core/
obj-$(CONFIG_DVB_CORE) += dvb-core/
+obj-$(CONFIG_AVB) += avb/

# There are both core and drivers at RC subtree - merge before drivers
obj-y += rc/
@@ -30,4 +31,4 @@ obj-y += rc/

obj-y += common/ platform/ pci/ usb/ mmc/ firewire/
obj-$(CONFIG_VIDEO_DEV) += radio/
-
+obj-$(CONFIG_MEDIA_AVB_ALSA) += avb/
diff --git a/drivers/media/avb/Makefile b/drivers/media/avb/Makefile
new file mode 100644
index 0000000..5d6302c
--- /dev/null
+++ b/drivers/media/avb/Makefile
@@ -0,0 +1,5 @@
+#
+# Makefile for the ALSA shim in AVB/TSN
+#
+
+obj-$(CONFIG_MEDIA_AVB_ALSA) += avb_alsa.o
diff --git a/drivers/media/avb/avb_alsa.c b/drivers/media/avb/avb_alsa.c
new file mode 100644
index 0000000..9aff7d3
--- /dev/null
+++ b/drivers/media/avb/avb_alsa.c
@@ -0,0 +1,742 @@
+/* Copyright 2016 Cisco Systems, Inc. and/or its affiliates. All rights
+ * reserved.
+ *
+ * This program is free software; you may redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; version 2 of the License.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+ * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+ * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+ * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
+ * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
+ * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
+ * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+#include <linux/platform_device.h>
+#include <sound/pcm_params.h>
+#include <linux/module.h>
+#include <linux/slab.h>
+#include <sound/core.h>
+#include <sound/pcm.h>
+
+#include <linux/tsn.h>
+#include "tsn_iec61883.h"
+
+struct avb_chip {
+ struct snd_card *card;
+ struct tsn_link *link;
+ struct snd_pcm *pcm;
+ struct snd_pcm_substream *substream;
+
+ /* Need a reference to this when we unregister the platform
+ * driver.
+ */
+ struct platform_device *device;
+
+ /* on first copy, we set a few values, use this to make sure we
+ * only do this once.
+ */
+ u8 first_copy;
+
+ u8 sample_size;
+ u8 channels;
+
+ /* current idx in 10ms set of frames
+ * class A: 80
+ * class B: 40
+ *
+ * This is mostly relevant for 44.1kHz samplefreq
+ */
+ u8 num_10ms_series;
+
+ u32 sample_freq;
+};
+
+/* currently, only playback is implemented in TSN layer
+ *
+
+ * FIXMEs: (should be set according to the active TSN link)
+ * - format
+ * - rates
+ * - channels
+ */
+static struct snd_pcm_hardware snd_avb_hw = {
+ .info = SNDRV_PCM_INFO_INTERLEAVED,
+ .formats = SNDRV_PCM_FMTBIT_S16_LE,
+ .rates = SNDRV_PCM_RATE_44100 | SNDRV_PCM_RATE_48000,
+ .rate_min = 44100,
+ .rate_max = 48000,
+ .channels_min = 2,
+ .channels_max = 2,
+ .period_bytes_min = 4096,
+ .period_bytes_max = 32768,
+ .buffer_bytes_max = 32768,
+ .periods_min = 1,
+ .periods_max = 1024,
+ .fifo_size = 0,
+};
+
+static size_t snd_avb_copy_size(struct tsn_link *link);
+
+
+static int _set_chip_values(struct avb_chip *avb_chip,
+ struct snd_pcm_runtime *runtime)
+{
+ if (!avb_chip->first_copy)
+ return 0;
+
+
+ /*
+ * first copy, we now know that runtime has all the correct
+ * values set, we can grab channels and rate. Sample_size
+ * (runtime->format) is currently hard-coded to S16_LE.
+ */
+ avb_chip->channels = runtime->channels;
+ avb_chip->sample_freq = runtime->rate;
+ avb_chip->sample_size = 16;
+
+ if (snd_avb_copy_size(avb_chip->link) > avb_chip->link->max_payload_size) {
+ pr_err("%s: Resulting payload-size is larger (%zd) than available (%u)\n",
+ __func__, snd_avb_copy_size(avb_chip->link),
+ avb_chip->link->max_payload_size);
+ return -EINVAL;
+ }
+ avb_chip->first_copy = 0;
+ return 0;
+}
+
+static int _snd_avb_open(struct avb_chip *avb_chip,
+ struct snd_pcm_runtime *runtime)
+{
+ /*
+ * We do not know what some of these values are until we see the
+ * first copy. We set to sane defaults where we don't have exact
+ * content.
+ */
+ avb_chip->channels = 0;
+ avb_chip->sample_size = 0;
+ avb_chip->sample_freq = 0;
+ avb_chip->num_10ms_series = 0;
+ avb_chip->first_copy = 1;
+
+ runtime->hw = snd_avb_hw;
+ runtime->buffer_size = avb_chip->link->buffer_size;
+ return 0;
+}
+
+/*
+ * bytes_to_frames()
+ * frames_to_bytes()
+ *
+ * frames_to_bytes(runtime, runtrime->period_size);
+ *
+ * Interrupt callbacks:
+ * The field traonsfer_ack_begin and transfer_ack_end are called at the
+ * beginning and at the end of snd_pcm_period_elapsed(), respectively.
+ */
+static int snd_avb_playback_open(struct snd_pcm_substream *substream)
+{
+ struct snd_pcm_runtime *runtime = substream->runtime;
+ struct avb_chip *avb_chip = snd_pcm_substream_chip(substream);
+ int ret = 0;
+
+ /*
+ * we've opened the PCM before probe returned properly and
+ * stored link in the struct.
+ */
+ if (!avb_chip || !avb_chip->link) {
+ pr_err("%s: Chip-data or link not available, cannot continue\n",
+ __func__);
+ return -EINVAL;
+ }
+ if (!avb_chip->link->estype_talker) {
+ pr_info("Link (%llu) not registered as Talker, cannot do playback\n",
+ avb_chip->link->stream_id);
+ return -EINVAL;
+ }
+
+ ret = _snd_avb_open(avb_chip, runtime);
+ if (ret < 0) {
+ pr_err("%s: Could not open playback-device (requested %d ch, %zd buffer)",
+ __func__, avb_chip->channels,
+ avb_chip->link->buffer_size);
+ return ret;
+ }
+ pr_info("%s: %d channel PCM stream opened successfully, buffersize: %zd\n",
+ __func__, avb_chip->channels, avb_chip->link->buffer_size);
+ return 0;
+}
+
+static int snd_avb_playback_close(struct snd_pcm_substream *substream)
+{
+ struct avb_chip *avb_chip = snd_pcm_substream_chip(substream);
+
+ tsn_lb_disable(avb_chip->link);
+
+ pr_info("%s: something happened\n", __func__);
+ return 0;
+}
+
+/*
+ * snd_avb snd_avb.0: BUG: ,
+ * pos = 12288,
+ * buffer size = 8192,
+ * period size = 2048
+ *
+ * Playback is when we *send* data to a remote speaker
+ */
+static int snd_avb_playback_copy(struct snd_pcm_substream *substream,
+ int channel,
+ snd_pcm_uframes_t pos,
+ void *src,
+ snd_pcm_uframes_t count)
+{
+ struct snd_pcm_runtime *runtime = substream->runtime;
+ struct avb_chip *avb_chip = snd_pcm_substream_chip(substream);
+ size_t bytes;
+ int ret;
+
+ /*
+ * From alsadoc:
+ *
+ * You need to check the channel argument, and if it's -1, copy
+ * the whole channels. Otherwise, you have to copy only the
+ * specified channel. Please check isa/gus/gus_pcm.c as an
+ * example.
+ */
+ if (channel != -1) {
+ pr_err("%s: partial copy not supportet\n", __func__);
+ return -EINVAL;
+ }
+
+ ret = _set_chip_values(avb_chip, runtime);
+ if (ret != 0)
+ return ret;
+
+ bytes = frames_to_bytes(runtime, count);
+ ret = tsn_buffer_write(avb_chip->link, src, bytes);
+ if (ret != bytes) {
+ pr_err("%s: Incorrect copy (%zd, %d) corruption possible\n",
+ __func__, bytes, ret);
+ return -EIO;
+ }
+ return 0;
+}
+
+static int snd_avb_capture_open(struct snd_pcm_substream *substream)
+{
+ struct snd_pcm_runtime *runtime = substream->runtime;
+ struct avb_chip *avb_chip = snd_pcm_substream_chip(substream);
+ int ret = 0;
+
+ if (!avb_chip || !avb_chip->link) {
+ pr_err("%s: Chip-data or link not available, cannot continue\n",
+ __func__);
+ return -EINVAL;
+ }
+ if (avb_chip->link->estype_talker) {
+ pr_info("Link (%llu) registered as Talker, cannot capture\n",
+ avb_chip->link->stream_id);
+ return -EINVAL;
+ }
+ ret = _snd_avb_open(avb_chip, runtime);
+ if (ret < 0) {
+ pr_err("%s: Could not open capture-device (requested %d ch, %zd buffer)",
+ __func__, avb_chip->channels,
+ avb_chip->link->buffer_size);
+ return ret;
+ }
+ tsn_lb_enable(avb_chip->link);
+ pr_info("%s: %d channel PCM stream opened successfully, buffersize: %zd\n",
+ __func__, avb_chip->channels, avb_chip->link->buffer_size);
+ return 0;
+}
+
+static int snd_avb_capture_close(struct snd_pcm_substream *substream)
+{
+ struct avb_chip *avb_chip = snd_pcm_substream_chip(substream);
+
+ if (!avb_chip || !avb_chip->link)
+ return -EINVAL;
+ pr_err("%s: closing stream\n", __func__);
+
+ tsn_lb_disable(avb_chip->link);
+
+ return 0;
+}
+
+static int snd_avb_capture_copy(struct snd_pcm_substream *substream,
+ int channel,
+ snd_pcm_uframes_t pos,
+ void *src,
+ snd_pcm_uframes_t count)
+{
+ struct snd_pcm_runtime *runtime = substream->runtime;
+ struct avb_chip *avb_chip = snd_pcm_substream_chip(substream);
+ size_t bytes;
+ int ret;
+
+ bytes = frames_to_bytes(runtime, count);
+ ret = tsn_buffer_read(avb_chip->link, src, bytes);
+ if (ret != bytes) {
+ pr_err("%s: incorrect copy (%zd, %d), corrupt capture possible\n",
+ __func__, bytes, ret);
+ tsn_lb_disable(avb_chip->link);
+ return -EIO;
+ }
+ return 0;
+}
+
+static int snd_avb_silence(struct snd_pcm_substream *substream,
+ int channel, snd_pcm_uframes_t pos,
+ snd_pcm_uframes_t count)
+{
+ /* FIXME, should do more than nothing */
+ return 0;
+}
+
+/*
+ * Called when the client defines buffer_size, period_size, format etc
+ * for the pcm substream.
+ *
+ * This is where link->buffer is allocated and link->buffer_size is
+ * defined.
+ *
+ * We are called in the beginning of snd_pcm_hw_params in
+ * sound/core/pcm_native.c, we cannot override runtime-values as they
+ * are updated from hw_params.
+ */
+static int snd_avb_pcm_hw_params(struct snd_pcm_substream *substream,
+ struct snd_pcm_hw_params *hw_params)
+{
+ struct avb_chip *avb_chip = snd_pcm_substream_chip(substream);
+ unsigned int bsize = params_buffer_bytes(hw_params);
+ int ret = 0;
+
+ /* We need this reference for the refill callback so that we can
+ * call snd_pcm_period_elapsed();
+ */
+ avb_chip->substream = substream;
+ ret = tsn_set_buffer_size(avb_chip->link, bsize);
+ if (ret < 0) {
+ pr_err("%s: could not set buffer_size (alsa requested too large? (%d)\n",
+ __func__, ret);
+ goto out;
+ }
+
+ avb_chip->num_10ms_series = 0;
+ pr_info("%s: successfully set hw-params\n", __func__);
+out:
+ return ret;
+}
+
+static int snd_avb_pcm_hw_free(struct snd_pcm_substream *substream)
+{
+ struct avb_chip *avb_chip = snd_pcm_substream_chip(substream);
+
+ if (!avb_chip || !avb_chip->link)
+ return -EINVAL;
+ tsn_clear_buffer_size(avb_chip->link);
+ pr_info("%s: something happened\n", __func__);
+ avb_chip->substream = NULL;
+ return 0;
+}
+
+static int snd_avb_pcm_prepare(struct snd_pcm_substream *substream)
+{
+ /* verify that samplerate, freq and size is what we have set in
+ * the link.
+ */
+
+ return 0;
+}
+
+/*
+ * When the PCM stream is started, stopped, paused etc.
+ *
+ * Atomic function (some lock is being held by PCM layer)
+ */
+static int snd_avb_pcm_trigger(struct snd_pcm_substream *substream,
+ int cmd)
+{
+ struct avb_chip *avb_chip = snd_pcm_substream_chip(substream);
+
+ switch (cmd) {
+ case SNDRV_PCM_TRIGGER_START:
+ case SNDRV_PCM_TRIGGER_RESUME:
+ /* pr_err("%s: starting for some reason\n", __func__); */
+ tsn_lb_enable(avb_chip->link);
+ break;
+ case SNDRV_PCM_TRIGGER_STOP:
+ case SNDRV_PCM_TRIGGER_SUSPEND:
+ /* memset buffer to 0 */
+ /* pr_err("%s: stopping for some reason\n", __func__); */
+ tsn_lb_disable(avb_chip->link);
+ break;
+ default:
+ pr_info("%s: cmd: %d (return -EINVAL)\n", __func__, cmd);
+ return -EINVAL;
+ }
+ return 0;
+}
+
+/*
+ * current hw-position in the buffer, in frames from 0 to buffer_size -1
+ *
+ * Need to know where the hw-pointer is and how this corresponds to the
+ * underlying TSN-buffer setup
+ *
+ * Atomic function (some lock is being held by PCM layer)
+ *
+ */
+static snd_pcm_uframes_t snd_avb_pcm_pointer(struct snd_pcm_substream *substream)
+{
+ struct avb_chip *avb_chip = snd_pcm_substream_chip(substream);
+ struct tsn_link *link = avb_chip->link;
+ snd_pcm_uframes_t pointer;
+
+ if (link->estype_talker)
+ pointer = bytes_to_frames(substream->runtime,
+ link->tail - link->buffer);
+ else
+ pointer = bytes_to_frames(substream->runtime,
+ link->head - link->buffer);
+ return pointer;
+}
+
+static struct snd_pcm_ops snd_avb_playback_ops = {
+ .open = snd_avb_playback_open,
+ .close = snd_avb_playback_close,
+ .copy = snd_avb_playback_copy,
+ .silence = snd_avb_silence,
+ .ioctl = snd_pcm_lib_ioctl,
+ .hw_params = snd_avb_pcm_hw_params,
+ .hw_free = snd_avb_pcm_hw_free,
+ .prepare = snd_avb_pcm_prepare,
+ .trigger = snd_avb_pcm_trigger,
+ .pointer = snd_avb_pcm_pointer,
+};
+
+static struct snd_pcm_ops snd_avb_capture_ops = {
+ .open = snd_avb_capture_open,
+ .close = snd_avb_capture_close,
+ .copy = snd_avb_capture_copy,
+ .silence = snd_avb_silence,
+ .ioctl = snd_pcm_lib_ioctl,
+ .hw_params = snd_avb_pcm_hw_params,
+ .hw_free = snd_avb_pcm_hw_free,
+ .prepare = snd_avb_pcm_prepare,
+ .trigger = snd_avb_pcm_trigger,
+ .pointer = snd_avb_pcm_pointer,
+};
+
+/*
+ * Callback for tsn_core for moving data into the buffer.
+ *
+ * This should be a wrapper (replace it with) the refill-functionality ALSA use.
+ */
+static size_t snd_avb_refill(struct tsn_link *link)
+{
+ struct avb_chip *avb_chip = link->media_chip;
+
+ if (avb_chip && avb_chip->substream) {
+ snd_pcm_period_elapsed(avb_chip->substream);
+ return 0;
+ }
+ return -EINVAL;
+}
+
+static size_t snd_avb_drain(struct tsn_link *link)
+{
+ struct avb_chip *avb_chip = link->media_chip;
+
+ if (avb_chip && avb_chip->substream) {
+ snd_pcm_period_elapsed(avb_chip->substream);
+ return 0;
+ }
+ return -EINVAL;
+}
+
+static size_t snd_avb_hdr_size(struct tsn_link *link)
+{
+ /* return the size of the iec61883-6 audio header */
+ return _iec61883_hdr_len();
+}
+
+static size_t snd_avb_copy_size(struct tsn_link *link)
+{
+ struct avb_chip *chip = link->media_chip;
+ /* use values in avb_chip, not link */
+ size_t framesize = (chip->sample_size >> 3) * chip->channels;
+ size_t numframes = 0;
+
+ if (!chip->sample_freq)
+ return link->max_payload_size;
+
+ /* size of each frame (samples per frame, sample-size && class)
+ * sample_size: 16 -> 2
+ * spframe : 12 (class b)
+ * channels: 2
+ *
+ * framesize: 2*12*2 -> 48
+ */
+
+ switch (chip->sample_freq) {
+ case 44100:
+ /*
+ * Class B: 40 frames, first 12 bytes, next 39 should be 11
+ */
+ if (!link->class_a) {
+ numframes = (chip->num_10ms_series ? 11 : 12);
+ chip->num_10ms_series++;
+ if (chip->num_10ms_series > 39)
+ chip->num_10ms_series = 0;
+ } else {
+ /* Class A slightly more involved
+ * Need 41 6 bytes and 39 5 bytes
+ *
+ * If 0th is set to 6, remaining odd idx should
+ * be 6, even (except 0th) to be 6
+ */
+ numframes = 5;
+ if (!chip->num_10ms_series ||
+ (chip->num_10ms_series % 0x2))
+ numframes++;
+ chip->num_10ms_series++;
+ if (chip->num_10ms_series > 79)
+ chip->num_10ms_series = 0;
+ }
+ break;
+ case 48000:
+ numframes = (link->class_a ? 6 : 12);
+ break;
+ default:
+ pr_err("Unsupported sample_freq (%d), disabling link\n",
+ chip->sample_freq);
+ tsn_lb_disable(link);
+ return -EINVAL;
+ }
+ return numframes * framesize;
+}
+
+static void snd_avb_assemble_iidc(struct tsn_link *link,
+ struct avtpdu_header *header, size_t bytes)
+{
+ _iec61883_hdr_assemble(header, bytes);
+}
+
+static int snd_avb_validate_iidc(struct tsn_link *link,
+ struct avtpdu_header *header)
+{
+ return _iec61883_hdr_verify(header);
+}
+
+static void *snd_avb_get_payload_data(struct tsn_link *link,
+ struct avtpdu_header *header)
+{
+ return _iec61883_payload(header);
+}
+
+static int snd_avb_new_pcm(struct avb_chip *avb_chip, int device)
+{
+ struct snd_pcm *pcm;
+ int err;
+
+ err = snd_pcm_new(avb_chip->card, "AVB PCM", device, 1, 1, &pcm);
+ if (err < 0)
+ return err;
+ pcm->private_data = avb_chip;
+ strcpy(pcm->name, "AVB PCM");
+ avb_chip->pcm = pcm;
+
+ /* only playback at the moment, once we implement capture, we
+ * need to grab the Talker/Listener from TSN link
+ */
+ snd_pcm_set_ops(pcm, SNDRV_PCM_STREAM_PLAYBACK, &snd_avb_playback_ops);
+ snd_pcm_set_ops(pcm, SNDRV_PCM_STREAM_CAPTURE, &snd_avb_capture_ops);
+
+ return 0;
+
+}
+static int snd_avb_probe(struct platform_device *devptr)
+{
+ int err;
+ struct snd_card *card;
+ struct avb_chip *avb_chip;
+
+ pr_info("%s: starting\n", __func__);
+
+ /*
+ * older kernel use snd_card_create. This is handled by
+ * tsn_compat.h in an attempt to make it easier to backport to
+ * older kernels.
+ */
+ err = snd_card_new(&devptr->dev, 1, "avb", THIS_MODULE,
+ sizeof(struct avb_chip), &card);
+ if (err < 0) {
+ pr_err("%s: trouble creating new card -> %d\n",
+ __func__, err);
+ return err;
+ }
+ avb_chip = card->private_data;
+ avb_chip->card = card;
+
+
+ /* create PCM device*/
+ err = snd_avb_new_pcm(avb_chip, 0);
+ if (err < 0) {
+ pr_err("%s: could not create new PCM device\n", __func__);
+ goto err_out;
+ }
+
+ /* register card */
+ pr_info("%s: ready to register card\n", __func__);
+ strcpy(card->driver, "Avb");
+ strcpy(card->shortname, "Avb");
+ sprintf(card->longname, "Avb %i", devptr->id + 1);
+ err = snd_card_register(card);
+ if (err < 0) {
+ pr_err("%s: Could not register card -> %d\n",
+ __func__, err);
+ snd_card_free(card);
+ return err;
+ }
+
+ if (err == 0) {
+ platform_set_drvdata(devptr, card);
+ pr_info("%s: Successfully initialized %s\n",
+ __func__, card->shortname);
+ return 0;
+ }
+err_out:
+ snd_card_free(card);
+ return err;
+}
+
+/*
+ * We are here as a result from being removed via
+ * tsn_link->shim_ops->media_close, which is snd_avb_close()
+ */
+static int snd_avb_remove(struct platform_device *devptr)
+{
+ struct snd_card *card = platform_get_drvdata(devptr);
+ struct avb_chip *avb_chip = card->private_data;
+
+ /* Make sure link holds no ref to this now dead card */
+ if (avb_chip && avb_chip->link) {
+ avb_chip->link->media_chip = NULL;
+ avb_chip->link = NULL;
+ }
+
+ /* call into link->ops->media_close() ? */
+ snd_card_free(card);
+ return 0;
+}
+
+static struct platform_driver snd_avb_driver = {
+ .probe = snd_avb_probe,
+ .remove = snd_avb_remove,
+ .driver = {
+ .name = "snd_avb",
+ .pm = NULL, /* don't care about Power Management */
+ },
+};
+
+static int snd_avb_close(struct tsn_link *link)
+{
+ struct avb_chip *avb_chip = link->media_chip;
+
+ if (!link->media_chip)
+ return 0;
+
+ pr_info("%s: Removing device\n", __func__);
+
+ platform_device_unregister(avb_chip->device);
+ /* platform unregister will call into snd_avb_remove */
+ platform_driver_unregister(&snd_avb_driver);
+
+ /* update link to remove pointer to now invalid memory */
+ link->media_chip = NULL;
+ return 0;
+}
+
+static int snd_avb_new(struct tsn_link *link)
+{
+ struct avb_chip *avb_chip;
+ struct snd_card *card;
+ struct platform_device *device;
+ int err;
+
+ err = platform_driver_register(&snd_avb_driver);
+ if (err < 0) {
+ pr_info("%s: trouble registering driver %d, unreg. partial driver and abort.\n",
+ __func__, err);
+ return err;
+ }
+
+ /*
+ * We only register a single card for now, look to
+ * /sys/devices/platform/snd_avb.0 for content.
+ *
+ * Probe will be triggered if name is same as .name in platform_driver
+ */
+ device = platform_device_register_simple("snd_avb", 0, NULL, 0);
+ if (IS_ERR(device)) {
+ pr_info("%s: ERROR registering simple platform-device\n",
+ __func__);
+ platform_driver_unregister(&snd_avb_driver);
+ return -ENODEV;
+ }
+
+ /* store data in driver so we can access it in .probe */
+ card = platform_get_drvdata(device);
+ if (card == NULL) {
+ pr_info("%s: Did not get anything from platform_get_drvdata()\n",
+ __func__);
+ platform_device_unregister(device);
+ return -ENODEV;
+ }
+ avb_chip = card->private_data;
+ avb_chip->device = device;
+ avb_chip->link = link;
+
+ link->media_chip = avb_chip;
+
+ return 0;
+}
+
+static struct tsn_shim_ops shim_ops = {
+ .shim_name = "alsa",
+ .probe = snd_avb_new,
+ .buffer_refill = snd_avb_refill,
+ .buffer_drain = snd_avb_drain,
+ .media_close = snd_avb_close,
+ .hdr_size = snd_avb_hdr_size,
+ .copy_size = snd_avb_copy_size,
+ .assemble_header = snd_avb_assemble_iidc,
+ .validate_header = snd_avb_validate_iidc,
+ .get_payload_data = snd_avb_get_payload_data,
+};
+
+static int __init avb_alsa_init(void)
+{
+ if (tsn_shim_register_ops(&shim_ops)) {
+ pr_err("Could not register ALSA-shim with TSN\n");
+ return -EINVAL;
+ }
+ pr_info("AVB ALSA added OK\n");
+ return 0;
+}
+
+static void __exit avb_alsa_exit(void)
+{
+ tsn_shim_deregister_ops(&shim_ops);
+}
+
+module_init(avb_alsa_init);
+module_exit(avb_alsa_exit);
+MODULE_AUTHOR("Henrik Austad");
+MODULE_LICENSE("GPL");
+MODULE_DESCRIPTION("TSN ALSA shim driver");
diff --git a/drivers/media/avb/tsn_iec61883.h b/drivers/media/avb/tsn_iec61883.h
new file mode 100644
index 0000000..bf26138
--- /dev/null
+++ b/drivers/media/avb/tsn_iec61883.h
@@ -0,0 +1,124 @@
+#ifndef TSN_IEC61883_H
+#define TSN_IEC61883_H
+#include <linux/tsn.h>
+
+/*
+ * psh:
+ * tag:2
+ * channel:6
+ * tcode:4
+ * sy:4
+ * See IEEE 1722.1 :: 6.2 for details
+ */
+struct iec61883_tag {
+ u8 tag:2;
+ u8 channel:6;
+ u8 tcode:4;
+ u8 sy:4;
+} __packed;
+
+struct iec61883_audio_header {
+ u8 sid:6;
+ u8 cip_1:2;
+
+ u8 dbs:8;
+
+ u8 rsv:2; /* reserved */
+ u8 sph:1;
+ u8 qpc:3;
+ u8 fn:2;
+
+ u8 dbc;
+
+ u8 fmt:6;
+ u8 cip_2:2;
+ u8 fdf;
+ u16 syt;
+ u8 payload[0];
+} __packed;
+
+static inline size_t _iec61883_hdr_len(void)
+{
+ return sizeof(struct iec61883_audio_header);
+}
+
+static inline int _iec61883_hdr_verify(struct avtpdu_header *hdr)
+{
+ struct iec61883_audio_header *dh;
+ struct iec61883_tag *psh;
+
+ if (hdr->subtype != AVTP_61883_IIDC)
+ return -EINVAL;
+ dh = (struct iec61883_audio_header *)&hdr->data;
+ psh = (struct iec61883_tag *)&hdr->psh;
+
+ /* Verify 61883 header */
+ if (psh->tag != 1 || psh->channel != 31 ||
+ psh->tcode != 0xA || psh->sy != 0)
+ return -EINVAL;
+
+ /* check flags that should be static from frame to frame */
+ if (dh->cip_1 != 0 || dh->sid != 0x3f || dh->qpc != 0 || dh->fn != 0 ||
+ dh->sph != 0 || dh->cip_2 != 2)
+ return -EINVAL;
+
+ if (dh->dbs != ntohs(hdr->sd_len)*2 || dh->dbc != hdr->seqnr)
+ return -EINVAL;
+
+ return 0;
+}
+
+static inline void _iec61883_hdr_assemble(struct avtpdu_header *hdr,
+ size_t bytes)
+{
+ struct iec61883_tag *psh;
+ struct iec61883_audio_header *dh;
+
+ if (bytes > 0x7f)
+ pr_warn("%s: hdr->dbs will overflow, malformed frame will be the result\n",
+ __func__);
+
+
+ hdr->subtype = AVTP_61883_IIDC;
+
+ /* IIDC 61883 header */
+ psh = (struct iec61883_tag *)&hdr->psh;
+ psh->tag = 1;
+ psh->channel = 31; /* 0x1f */
+ psh->tcode = 0xA;
+ psh->sy = 0;
+
+ dh = (struct iec61883_audio_header *)&hdr->data;
+ dh->cip_1 = 0;
+ dh->sid = 63; /* 0x3f */
+ dh->dbs = (u8)(bytes*2); /* number of quadlets of data in AVTPDU */
+ dh->qpc = 0;
+ dh->fn = 0;
+ dh->sph = 0;
+ dh->dbc = hdr->seqnr;
+ dh->cip_2 = 2;
+
+ /*
+ * FMT (Format ID): same as specified in iec 61883-1:2003
+ *
+ * For IEC 61883-6, it shall be 0x10 (16) to define Audio and
+ * Music data
+ */
+ dh->fmt = 0x10;
+
+ /* FIXME: find value
+ * Could be sampling-freq, but 8 bits give 0 - 65kHz sampling.
+ */
+ dh->fdf = 0;
+
+ dh->syt = 0xFFFF;
+}
+
+static inline void *_iec61883_payload(struct avtpdu_header *hdr)
+{
+ struct iec61883_audio_header *dh = (struct iec61883_audio_header *)&hdr->data;
+ /* TODO: add some basic checks before returning payload ? */
+ return &dh->payload;
+}
+
+#endif /* TSN_IEC61883_H */
--
2.7.4