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

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  [very-RFC 7/8] AVB ALSA - Add ALSA shim for TSN Henrik Austad <henrik@austad.us> - 2016-06-12 01:10 +0200
    Re: [very-RFC 7/8] AVB ALSA - Add ALSA shim for TSN Richard Cochran <richardcochran@gmail.com> - 2016-06-15 13:50 +0200
      Re: [very-RFC 7/8] AVB ALSA - Add ALSA shim for TSN Henrik Austad <henrik@austad.us> - 2016-06-15 14:20 +0200
        Re: [very-RFC 7/8] AVB ALSA - Add ALSA shim for TSN Richard Cochran <richardcochran@gmail.com> - 2016-06-15 14:50 +0200

#1420095 — [very-RFC 7/8] AVB ALSA - Add ALSA shim for TSN

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

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#1422927

Now that I understand better...

On Sun, Jun 12, 2016 at 01:01:35AM +0200, Henrik Austad wrote:
> 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

This is exactly why configfs is the wrong interface.  If you implement
the AVB device in alsa-lib user space, then you can handle the
reservations, configuration, UDP sockets, etc, in a way transparent to
the aplay program.

Heck, if done properly, your layer could discover the AVB nodes in the
network and present each one as a separate device...

Thanks,
Richard

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#1422969

[Multipart message — attachments visible in raw view] — view raw

On Wed, Jun 15, 2016 at 01:49:08PM +0200, Richard Cochran wrote:
> Now that I understand better...
> 
> On Sun, Jun 12, 2016 at 01:01:35AM +0200, Henrik Austad wrote:
> > 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
> 
> This is exactly why configfs is the wrong interface.  If you implement
> the AVB device in alsa-lib user space, then you can handle the
> reservations, configuration, UDP sockets, etc, in a way transparent to
> the aplay program.

And how would v4l2 benefit from this being in alsalib? Should we require 
both V4L and ALSA to implement the same, or should we place it in a common 
place for all.

And what about those systems that want to use TSN but is not a 
media-device, they should be given a raw-socket to send traffic over, 
should they also implement something in a library?

So no, here I think configfs is an apt choice.

> Heck, if done properly, your layer could discover the AVB nodes in the
> network and present each one as a separate device...

No, you definately do not want the kernel to automagically add devices 
whenever something pops up on the network, for this you need userspace to 
be in control. 1722.1 should not be handled in-kernel.


-- 
Henrik Austad

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#1422980

On Wed, Jun 15, 2016 at 02:13:03PM +0200, Henrik Austad wrote:
> On Wed, Jun 15, 2016 at 01:49:08PM +0200, Richard Cochran wrote:
> And how would v4l2 benefit from this being in alsalib? Should we require 
> both V4L and ALSA to implement the same, or should we place it in a common 
> place for all.

I don't require V4L to implement anything.  You were the one wanting
AVB "devices".  Go ahead and do that, but in user space please.  We
don't want to have kernel code that sends arbitrary Layer2 and UDP
media packets.

The example you present of using aplay over the network is a cute
idea, but after all it is a trivial application.  I have nothing
against creating virtual ALSA devices (if done properly), but that
model won't work for more realistic AVB networks.

> And what about those systems that want to use TSN but is not a 
> media-device, they should be given a raw-socket to send traffic over, 
> should they also implement something in a library?

A raw socket is the way to do it, yes.

Since TSN is about bandwidth reservation and time triggered Ethernet,
decoupled from the contents of the streams, each new TSN application
will have to see what works best.  If common ground is found, then a
library makes sense to do.

At this point, it is way too early to guess how that will look.  But
media packet formats clearly belong in user space.

> So no, here I think configfs is an apt choice.
> 
> > Heck, if done properly, your layer could discover the AVB nodes in the
> > network and present each one as a separate device...
> 
> No, you definately do not want the kernel to automagically add devices 
> whenever something pops up on the network, for this you need userspace to 
> be in control. 1722.1 should not be handled in-kernel.

The layer should be in user space.  Alsa-lib *is* user space.

Thanks,
Richard

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