greybus: gb-audio: Add integrated greybus audio driver

Message ID 1431115056-23206-1-git-send-email-john.stultz@linaro.org
State New
Headers show

Commit Message

John Stultz May 8, 2015, 7:57 p.m.
So here's the current greybus audio driver, which I
wanted to send out for more serious review and
consideration for merging.

I've tried to integrate much of the feedback from the
last round and most of the hotplug issues that I've found
have been resolved. I've tested this via gbsim, and the
Android ARA HAL layer seems to work with it.

Mark has also successfully played audio with this driver,
adding a few hacks to get the codec's i2c connection to
probe.

Current issues:
* Hotplug problem - When gbsim is killed, or the module
  removed, the greybus driver gets stuck since the android
  mediaserver process is holding the audio device open.
  Killing the mediaserver allows things to clean up and
  allows greybus to accept new gbsim connections. I have
  a workaround patch to the soc-core.c logic which converts
  the snd_card_free() call to snd_card_free_when_closed()
  which allows the greybus connection cleanup to finish.

Remaining todos:
* Probably need to break apart the mgmt_setup function
  to integrate better with the constraint logic. I took
  a really basic stab at this, but more is probably
  needed.
* Figure out how to properly find and tie in the
  codec's I2C bus-id to the driver.

This code requires that the kernel support the following
config options, which I've enabled in a separate kernel
patch:
	CONFIG_SND_SIMPLE_CARD
	CONFIG_SND_SOC_SPDIF
	CONFIG_SND_SOC_RT5645

I really can't calim to be the sole author of this, since
many many fixes and tweaks that have been folded in have
come from Mark Greer. His analsysis and debugging is really
what has made this dummy-framework driver evolve into an
actual audio driver. So much credit and thanks to Mark!

Signed-off-by: John Stultz <john.stultz@linaro.org>
---
 Makefile        |   8 +-
 audio-dai.c     | 103 ++++++++++++++
 audio-gb-cmds.c | 207 +++++++++++++++++++++++++++
 audio-pcm.c     | 262 ++++++++++++++++++++++++++++++++++
 audio.c         | 432 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 audio.h         | 100 +++++++++++++
 gpb.c           |   8 ++
 gpbridge.h      |   2 +-
 protocol.h      |   3 +
 9 files changed, 1122 insertions(+), 3 deletions(-)
 create mode 100644 audio-dai.c
 create mode 100644 audio-gb-cmds.c
 create mode 100644 audio-pcm.c
 create mode 100644 audio.c
 create mode 100644 audio.h

Patch hide | download patch | download mbox

diff --git a/Makefile b/Makefile
index 9945cb8..5158d87 100644
--- a/Makefile
+++ b/Makefile
@@ -10,7 +10,7 @@  greybus-y :=	core.o		\
 		protocol.o	\
 		operation.o
 
-gb-phy-y :=	gpb.o		\
+gb-phy-y :=	gpb.o	\
 		sdio.o	\
 		uart.o	\
 		pwm.o	\
@@ -18,7 +18,11 @@  gb-phy-y :=	gpb.o		\
 		hid.o	\
 		i2c.o	\
 		spi.o	\
-		usb.o
+		usb.o	\
+		audio.o		\
+		audio-pcm.o	\
+		audio-dai.o	\
+		audio-gb-cmds.o
 
 # Prefix all modules with gb-
 gb-vibrator-y := vibrator.o
diff --git a/audio-dai.c b/audio-dai.c
new file mode 100644
index 0000000..f2c8ca0
--- /dev/null
+++ b/audio-dai.c
@@ -0,0 +1,103 @@ 
+#include <linux/kernel.h>
+#include <linux/device.h>
+#include <linux/interrupt.h>
+#include <linux/module.h>
+#include <linux/platform_device.h>
+#include <linux/workqueue.h>
+#include <linux/i2c.h>
+#include <sound/core.h>
+#include <sound/pcm.h>
+#include <sound/pcm_params.h>
+#include <sound/soc.h>
+#include <sound/dmaengine_pcm.h>
+#include <sound/simple_card.h>
+#include "greybus.h"
+#include "gpbridge.h"
+#include "audio.h"
+
+/*
+ * This is the greybus cpu dai logic. It really doesn't do much
+ * other then provide the TRIGGER_START/STOP hooks that start
+ * and stop the timer sending audio data in the pcm logic.
+ */
+
+
+static int gb_dai_trigger(struct snd_pcm_substream *substream, int cmd,
+				struct snd_soc_dai *dai)
+{
+	struct snd_soc_pcm_runtime *rtd = substream->private_data;
+	struct gb_snd *snd_dev;
+
+
+	snd_dev = snd_soc_dai_get_drvdata(rtd->cpu_dai);
+
+	switch (cmd) {
+	case SNDRV_PCM_TRIGGER_START:
+		gb_pcm_hrtimer_start(snd_dev);
+		break;
+	case SNDRV_PCM_TRIGGER_STOP:
+		gb_pcm_hrtimer_stop(snd_dev);
+		break;
+	default:
+		return -EINVAL;
+	}
+	return 0;
+}
+
+/*
+ * XXX This is annoying, if we don't have a set_fmt function
+ * the subsystem returns -ENOTSUPP, which causes applications
+ * to fail, so add a dummy function here.
+ */
+static int gb_dai_set_fmt(struct snd_soc_dai *dai, unsigned int fmt)
+{
+	return 0;
+}
+
+static const struct snd_soc_dai_ops gb_dai_ops = {
+	.trigger	= gb_dai_trigger,
+	.set_fmt	= gb_dai_set_fmt,
+};
+
+struct snd_soc_dai_driver gb_cpu_dai = {
+	.name			= "gb-cpu-dai",
+	.playback = {
+		.rates		= GB_RATES,
+		.formats	= GB_FMTS,
+		.channels_min	= 1,
+		.channels_max	= 2,
+	},
+	.ops = &gb_dai_ops,
+};
+
+static const struct snd_soc_component_driver gb_soc_component = {
+	.name		= "gb-component",
+};
+
+static int gb_plat_probe(struct platform_device *pdev)
+{
+	struct gb_snd *snd_dev;
+	int ret;
+
+	snd_dev = (struct gb_snd *)pdev->dev.platform_data;
+	dev_set_drvdata(&pdev->dev, snd_dev);
+
+	ret = snd_soc_register_component(&pdev->dev, &gb_soc_component,
+							&gb_cpu_dai, 1);
+	return ret;
+}
+
+static int gb_plat_remove(struct platform_device *pdev)
+{
+	snd_soc_unregister_component(&pdev->dev);
+	snd_soc_unregister_platform(&pdev->dev);
+	return 0;
+}
+
+struct platform_driver gb_audio_plat_driver = {
+	.driver		= {
+		.name	= "gb-dai-audio",
+	},
+	.probe		= gb_plat_probe,
+	.remove		= gb_plat_remove,
+};
diff --git a/audio-gb-cmds.c b/audio-gb-cmds.c
new file mode 100644
index 0000000..ef31916
--- /dev/null
+++ b/audio-gb-cmds.c
@@ -0,0 +1,207 @@ 
+#include <linux/kernel.h>
+#include "greybus.h"
+#include "gpbridge.h"
+#include "audio.h"
+
+#define GB_I2S_MGMT_VERSION_MAJOR		0x00
+#define GB_I2S_MGMT_VERSION_MINOR		0x01
+
+#define GB_I2S_DATA_VERSION_MAJOR		0x00
+#define GB_I2S_MGMT_VERSION_MINOR		0x01
+
+/***********************************
+ * GB I2S helper functions
+ ***********************************/
+int gb_i2s_mgmt_get_version(struct gb_connection *connection)
+{
+	struct gb_protocol_version_response response;
+
+	memset(&response, 0, sizeof(response));
+	return gb_protocol_get_version(connection,
+				       GB_I2S_MGMT_TYPE_PROTOCOL_VERSION,
+				       NULL, 0, &response,
+				       GB_I2S_MGMT_VERSION_MAJOR);
+}
+
+int gb_i2s_data_get_version(struct gb_connection *connection)
+{
+	struct gb_protocol_version_response response;
+
+	memset(&response, 0, sizeof(response));
+	return gb_protocol_get_version(connection,
+				       GB_I2S_DATA_TYPE_PROTOCOL_VERSION,
+				       NULL, 0, &response,
+				       GB_I2S_DATA_VERSION_MAJOR);
+}
+
+int gb_i2s_mgmt_activate_cport(struct gb_connection *connection,
+				      uint16_t cport)
+{
+	struct gb_i2s_mgmt_activate_cport_request request;
+
+	memset(&request, 0, sizeof(request));
+	request.cport = cport;
+
+	return gb_operation_sync(connection, GB_I2S_MGMT_TYPE_ACTIVATE_CPORT,
+				 &request, sizeof(request), NULL, 0);
+}
+
+int gb_i2s_mgmt_deactivate_cport(struct gb_connection *connection,
+					uint16_t cport)
+{
+	struct gb_i2s_mgmt_deactivate_cport_request request;
+
+	memset(&request, 0, sizeof(request));
+	request.cport = cport;
+
+	return gb_operation_sync(connection, GB_I2S_MGMT_TYPE_DEACTIVATE_CPORT,
+				 &request, sizeof(request), NULL, 0);
+}
+
+int gb_i2s_mgmt_get_supported_configurations(
+	struct gb_connection *connection,
+	struct gb_i2s_mgmt_get_supported_configurations_response *get_cfg,
+	size_t size)
+{
+	return gb_operation_sync(connection,
+				 GB_I2S_MGMT_TYPE_GET_SUPPORTED_CONFIGURATIONS,
+				 NULL, 0, get_cfg, size);
+}
+
+int gb_i2s_mgmt_set_configuration(struct gb_connection *connection,
+			struct gb_i2s_mgmt_set_configuration_request *set_cfg)
+{
+	return gb_operation_sync(connection, GB_I2S_MGMT_TYPE_SET_CONFIGURATION,
+				 set_cfg, sizeof(*set_cfg), NULL, 0);
+}
+
+int gb_i2s_mgmt_set_samples_per_message(
+				struct gb_connection *connection,
+				uint16_t samples_per_message)
+{
+	struct gb_i2s_mgmt_set_samples_per_message_request request;
+
+	memset(&request, 0, sizeof(request));
+	request.samples_per_message = samples_per_message;
+
+	return gb_operation_sync(connection,
+				 GB_I2S_MGMT_TYPE_SET_SAMPLES_PER_MESSAGE,
+				 &request, sizeof(request), NULL, 0);
+}
+
+/*
+ * XXX This is sort of a generic "setup" function which  probably needs
+ * to be broken up, and tied into the constraints.
+ *
+ * I'm on the fence if we should just dictate that we only support
+ * 48k, 16bit, 2 channel, and avoid doign the whole probe for configurations
+ * and then picking one.
+ */
+int gb_i2s_mgmt_setup(struct gb_connection *connection)
+{
+	struct gb_i2s_mgmt_get_supported_configurations_response *get_cfg;
+	struct gb_i2s_mgmt_set_configuration_request set_cfg;
+	struct gb_i2s_mgmt_configuration *cfg;
+	size_t size;
+	int i, ret;
+
+	size = sizeof(*get_cfg) +
+	       (CONFIG_COUNT_MAX * sizeof(get_cfg->config[0]));
+
+	get_cfg = kzalloc(size, GFP_KERNEL);
+	if (!get_cfg)
+		return -ENOMEM;
+
+	ret = gb_i2s_mgmt_get_supported_configurations(connection, get_cfg,
+						       size);
+	if (ret) {
+		pr_err("get_supported_config failed: %d\n", ret);
+		goto free_get_cfg;
+	}
+
+	/* Pick 48KHz 16-bits/channel */
+	for (i = 0, cfg = get_cfg->config; i < CONFIG_COUNT_MAX; i++, cfg++) {
+		if ((cfg->sample_frequency == GB_SAMPLE_RATE) &&
+		    (cfg->num_channels == 2) &&
+		    (cfg->bytes_per_channel == 2) &&
+		    (cfg->byte_order & GB_I2S_MGMT_BYTE_ORDER_LE) &&
+		    (cfg->spatial_locations ==
+			(GB_I2S_MGMT_SPATIAL_LOCATION_FL |
+			 GB_I2S_MGMT_SPATIAL_LOCATION_FR)) &&
+		    (cfg->ll_protocol & GB_I2S_MGMT_PROTOCOL_I2S) &&
+		    (cfg->ll_mclk_role & GB_I2S_MGMT_ROLE_MASTER) &&
+		    (cfg->ll_bclk_role & GB_I2S_MGMT_ROLE_MASTER) &&
+		    (cfg->ll_wclk_role & GB_I2S_MGMT_ROLE_MASTER) &&
+		    (cfg->ll_wclk_polarity & GB_I2S_MGMT_POLARITY_NORMAL) &&
+		    (cfg->ll_wclk_change_edge & GB_I2S_MGMT_EDGE_FALLING) &&
+		    (cfg->ll_wclk_tx_edge & GB_I2S_MGMT_EDGE_FALLING) &&
+		    (cfg->ll_wclk_rx_edge & GB_I2S_MGMT_EDGE_RISING) &&
+		    (cfg->ll_data_offset == 1))
+			break;
+	}
+
+	if (i >= CONFIG_COUNT_MAX) {
+		pr_err("No valid configuration\n");
+		ret = -EINVAL;
+		goto free_get_cfg;
+	}
+
+	memcpy(&set_cfg, cfg, sizeof(set_cfg));
+	set_cfg.config.byte_order = GB_I2S_MGMT_BYTE_ORDER_LE;
+	set_cfg.config.ll_protocol = GB_I2S_MGMT_PROTOCOL_I2S;
+	set_cfg.config.ll_mclk_role = GB_I2S_MGMT_ROLE_MASTER;
+	set_cfg.config.ll_bclk_role = GB_I2S_MGMT_ROLE_MASTER;
+	set_cfg.config.ll_wclk_role = GB_I2S_MGMT_ROLE_MASTER;
+	set_cfg.config.ll_wclk_polarity = GB_I2S_MGMT_POLARITY_NORMAL;
+	set_cfg.config.ll_wclk_change_edge = GB_I2S_MGMT_EDGE_RISING;
+	set_cfg.config.ll_wclk_tx_edge = GB_I2S_MGMT_EDGE_FALLING;
+	set_cfg.config.ll_wclk_rx_edge = GB_I2S_MGMT_EDGE_RISING;
+
+	ret = gb_i2s_mgmt_set_configuration(connection, &set_cfg);
+	if (ret) {
+		pr_err("set_configuration failed: %d\n", ret);
+		goto free_get_cfg;
+	}
+
+	ret = gb_i2s_mgmt_set_samples_per_message(connection,
+						  CONFIG_SAMPLES_PER_MSG);
+	if (ret) {
+		pr_err("set_samples_per_msg failed: %d\n", ret);
+		goto free_get_cfg;
+	}
+
+	/* XXX Add start delay here (probably 1ms) */
+	ret = gb_i2s_mgmt_activate_cport(connection,
+					 CONFIG_I2S_REMOTE_DATA_CPORT);
+	if (ret) {
+		pr_err("activate_cport failed: %d\n", ret);
+		goto free_get_cfg;
+	}
+
+free_get_cfg:
+	kfree(get_cfg);
+	return ret;
+}
+
+int gb_i2s_send_data(struct gb_connection *connection,
+					void *req_buf, void *source_addr,
+					size_t len, int sample_num)
+{
+	struct gb_i2s_send_data_request *gb_req;
+	int ret;
+
+	gb_req = req_buf;
+	gb_req->sample_number = sample_num;
+
+	memcpy((void *)&gb_req->data[0], source_addr, len);
+
+	if (len < MAX_SEND_DATA_LEN)
+		for (; len < MAX_SEND_DATA_LEN; len++)
+			gb_req->data[len] = gb_req->data[len - SAMPLE_SIZE];
+
+	gb_req->size = len;
+
+	ret = gb_operation_sync(connection, GB_I2S_DATA_TYPE_SEND_DATA,
+				(void *) gb_req, SEND_DATA_BUF_LEN, NULL, 0);
+	return ret;
+}
diff --git a/audio-pcm.c b/audio-pcm.c
new file mode 100644
index 0000000..28b5e11
--- /dev/null
+++ b/audio-pcm.c
@@ -0,0 +1,262 @@ 
+#include <linux/kernel.h>
+#include <linux/device.h>
+#include <linux/interrupt.h>
+#include <linux/module.h>
+#include <linux/platform_device.h>
+#include <linux/workqueue.h>
+#include <linux/i2c.h>
+#include <sound/core.h>
+#include <sound/pcm.h>
+#include <sound/pcm_params.h>
+#include <sound/soc.h>
+#include <sound/dmaengine_pcm.h>
+#include <sound/simple_card.h>
+#include "greybus.h"
+#include "gpbridge.h"
+#include "audio.h"
+
+/*
+ * timer/workqueue logic for pushing pcm data.
+ *
+ * Since when we are playing audio, we don't get any
+ * status or feedback from the codec, we have to use a
+ * hrtimer to trigger sending data to the remote codec.
+ * However since the hrtimer runs in irq context, so we
+ * have to schedule a workqueue to actually send the
+ * greybus data.
+ */
+
+static void gb_pcm_work(struct work_struct *work)
+{
+	struct gb_snd *snd_dev = container_of(work, struct gb_snd, work);
+	struct snd_pcm_substream *substream = snd_dev->substream;
+	struct snd_pcm_runtime *runtime = substream->runtime;
+	unsigned int stride, frames, oldptr;
+	int period_elapsed;
+	char *address;
+	long len;
+
+	if (!snd_dev)
+		return;
+
+	if (!atomic_read(&snd_dev->running))
+		return;
+
+	address = runtime->dma_area + snd_dev->hwptr_done;
+
+	len = frames_to_bytes(runtime,
+			      runtime->buffer_size) - snd_dev->hwptr_done;
+	len = min(len, MAX_SEND_DATA_LEN);
+	gb_i2s_send_data(snd_dev->i2s_tx_connection, snd_dev->send_data_req_buf,
+				address, len, snd_dev->send_data_sample_count);
+
+	snd_dev->send_data_sample_count += CONFIG_SAMPLES_PER_MSG;
+
+	stride = runtime->frame_bits >> 3;
+	frames = len/stride;
+
+	snd_pcm_stream_lock(substream);
+	oldptr = snd_dev->hwptr_done;
+	snd_dev->hwptr_done += len;
+	if (snd_dev->hwptr_done >= runtime->buffer_size * stride)
+		snd_dev->hwptr_done -= runtime->buffer_size * stride;
+
+	frames = (len + (oldptr % stride)) / stride;
+
+	snd_dev->transfer_done += frames;
+	if (snd_dev->transfer_done >= runtime->period_size) {
+		snd_dev->transfer_done -= runtime->period_size;
+		period_elapsed = 1;
+	}
+
+	snd_pcm_stream_unlock(substream);
+	if (period_elapsed)
+		snd_pcm_period_elapsed(snd_dev->substream);
+}
+
+static enum hrtimer_restart gb_pcm_timer_function(struct hrtimer *hrtimer)
+{
+	struct gb_snd *snd_dev = container_of(hrtimer, struct gb_snd, timer);
+
+	if (!atomic_read(&snd_dev->running))
+		return HRTIMER_NORESTART;
+	queue_work(snd_dev->workqueue, &snd_dev->work);
+	hrtimer_forward_now(hrtimer, ns_to_ktime(CONFIG_PERIOD_NS));
+	return HRTIMER_RESTART;
+}
+
+void gb_pcm_hrtimer_start(struct gb_snd *snd_dev)
+{
+	atomic_set(&snd_dev->running, 1);
+	hrtimer_start(&snd_dev->timer, ns_to_ktime(CONFIG_PERIOD_NS),
+						HRTIMER_MODE_REL);
+}
+
+void gb_pcm_hrtimer_stop(struct gb_snd *snd_dev)
+{
+	atomic_set(&snd_dev->running, 0);
+	hrtimer_cancel(&snd_dev->timer);
+}
+
+static int gb_pcm_hrtimer_init(struct gb_snd *snd_dev)
+{
+	hrtimer_init(&snd_dev->timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
+	snd_dev->timer.function = gb_pcm_timer_function;
+	atomic_set(&snd_dev->running, 0);
+	snd_dev->workqueue = alloc_workqueue("gb-audio", WQ_HIGHPRI, 0);
+	if (!snd_dev->workqueue)
+		return -ENOMEM;
+	INIT_WORK(&snd_dev->work, gb_pcm_work);
+	return 0;
+}
+
+
+/*
+ * Core gb pcm structure
+ */
+static struct snd_pcm_hardware gb_plat_pcm_hardware = {
+	.info			= SNDRV_PCM_INFO_INTERLEAVED |
+				  SNDRV_PCM_INFO_MMAP        |
+				  SNDRV_PCM_INFO_MMAP_VALID,
+	.formats		= GB_FMTS,
+	.rates			= GB_RATES,
+	.rate_min		= 8000,
+	.rate_max		= GB_SAMPLE_RATE,
+	.channels_min		= 1,
+	.channels_max		= 2,
+	/* XXX - All the values below are junk */
+	.buffer_bytes_max	= 64 * 1024,
+	.period_bytes_min	= 32,
+	.period_bytes_max	= 8192,
+	.periods_min		= 2,
+	.periods_max		= 32,
+};
+
+static snd_pcm_uframes_t gb_pcm_pointer(struct snd_pcm_substream *substream)
+{
+	struct snd_soc_pcm_runtime *rtd = substream->private_data;
+	struct gb_snd *snd_dev;
+
+	snd_dev = snd_soc_dai_get_drvdata(rtd->cpu_dai);
+
+	return snd_dev->hwptr_done  / (substream->runtime->frame_bits >> 3);
+}
+
+static int gb_pcm_prepare(struct snd_pcm_substream *substream)
+{
+	struct snd_soc_pcm_runtime *rtd = substream->private_data;
+	struct gb_snd *snd_dev;
+
+	snd_dev = snd_soc_dai_get_drvdata(rtd->cpu_dai);
+	snd_dev->hwptr_done = 0;
+	snd_dev->transfer_done = 0;
+	return 0;
+}
+
+static unsigned int rates[] = {GB_SAMPLE_RATE};
+static struct snd_pcm_hw_constraint_list constraints_rates = {
+	.count = ARRAY_SIZE(rates),
+	.list = rates,
+	.mask = 0,
+};
+
+static int gb_pcm_open(struct snd_pcm_substream *substream)
+{
+	struct snd_pcm_runtime *runtime = substream->runtime;
+	struct snd_soc_pcm_runtime *rtd = substream->private_data;
+	struct gb_snd *snd_dev;
+	unsigned long flags;
+	int ret;
+
+	snd_dev = snd_soc_dai_get_drvdata(rtd->cpu_dai);
+
+	spin_lock_irqsave(&snd_dev->lock, flags);
+	runtime->private_data = snd_dev;
+	snd_dev->substream = substream;
+	ret = gb_pcm_hrtimer_init(snd_dev);
+	spin_unlock_irqrestore(&snd_dev->lock, flags);
+
+	if (ret)
+		return ret;
+
+	snd_soc_set_runtime_hwparams(substream, &gb_plat_pcm_hardware);
+
+	ret = snd_pcm_hw_constraint_list(substream->runtime, 0,
+					SNDRV_PCM_HW_PARAM_RATE,
+					&constraints_rates);
+	if (ret < 0)
+		return ret;
+
+	return snd_pcm_hw_constraint_integer(runtime,
+					     SNDRV_PCM_HW_PARAM_PERIODS);
+}
+
+static int gb_pcm_close(struct snd_pcm_substream *substream)
+{
+	substream->runtime->private_data = NULL;
+	return 0;
+}
+
+static int gb_pcm_hw_params(struct snd_pcm_substream *substream,
+				struct snd_pcm_hw_params *hw_params)
+{
+	return snd_pcm_lib_malloc_pages(substream,
+					params_buffer_bytes(hw_params));
+}
+
+static int gb_pcm_hw_free(struct snd_pcm_substream *substream)
+{
+	return snd_pcm_lib_free_pages(substream);
+}
+
+static struct snd_pcm_ops gb_pcm_ops = {
+	.open		= gb_pcm_open,
+	.close		= gb_pcm_close,
+	.ioctl		= snd_pcm_lib_ioctl,
+	.hw_params	= gb_pcm_hw_params,
+	.hw_free	= gb_pcm_hw_free,
+	.prepare	= gb_pcm_prepare,
+	.pointer	= gb_pcm_pointer,
+};
+
+static void gb_pcm_free(struct snd_pcm *pcm)
+{
+	snd_pcm_lib_preallocate_free_for_all(pcm);
+}
+
+static int gb_pcm_new(struct snd_soc_pcm_runtime *rtd)
+{
+	struct snd_pcm *pcm = rtd->pcm;
+
+	return snd_pcm_lib_preallocate_pages_for_all(
+			pcm,
+			SNDRV_DMA_TYPE_CONTINUOUS,
+			snd_dma_continuous_data(GFP_KERNEL),
+			PREALLOC_BUFFER, PREALLOC_BUFFER_MAX);
+}
+
+struct snd_soc_platform_driver gb_soc_platform = {
+	.ops		= &gb_pcm_ops,
+	.pcm_new	= gb_pcm_new,
+	.pcm_free	= gb_pcm_free,
+};
+
+static int gb_soc_platform_probe(struct platform_device *pdev)
+{
+	return snd_soc_register_platform(&pdev->dev, &gb_soc_platform);
+}
+
+static int gb_soc_platform_remove(struct platform_device *pdev)
+{
+	snd_soc_unregister_platform(&pdev->dev);
+	return 0;
+}
+
+struct platform_driver gb_audio_pcm_driver = {
+	.driver = {
+			.name = "gb-pcm-audio",
+			.owner = THIS_MODULE,
+	},
+	.probe = gb_soc_platform_probe,
+	.remove = gb_soc_platform_remove,
+};
diff --git a/audio.c b/audio.c
new file mode 100644
index 0000000..717e002
--- /dev/null
+++ b/audio.c
@@ -0,0 +1,432 @@ 
+#include <linux/kernel.h>
+#include <linux/device.h>
+#include <linux/interrupt.h>
+#include <linux/module.h>
+#include <linux/platform_device.h>
+#include <linux/workqueue.h>
+#include <linux/i2c.h>
+#include <sound/core.h>
+#include <sound/pcm.h>
+#include <sound/pcm_params.h>
+#include <sound/soc.h>
+#include <sound/dmaengine_pcm.h>
+#include <sound/simple_card.h>
+#include "greybus.h"
+#include "gpbridge.h"
+#include "audio.h"
+
+
+#define GB_AUDIO_DATA_DRIVER_NAME		"gb_audio_data"
+#define GB_AUDIO_MGMT_DRIVER_NAME		"gb_audio_mgmt"
+
+/*
+ * gb_snd management functions
+ */
+static DEFINE_SPINLOCK(gb_snd_list_lock);
+static LIST_HEAD(gb_snd_list);
+static int device_count;
+
+static struct gb_snd *gb_find_snd(int bundle_id)
+{
+	struct gb_snd *tmp, *ret = NULL;
+	unsigned long flags;
+
+	spin_lock_irqsave(&gb_snd_list_lock, flags);
+	list_for_each_entry(tmp, &gb_snd_list, list)
+		if (tmp->gb_bundle_id == bundle_id) {
+			ret = tmp;
+			break;
+		}
+	spin_unlock_irqrestore(&gb_snd_list_lock, flags);
+	return ret;
+}
+
+static struct gb_snd *gb_get_snd(int bundle_id)
+{
+	struct gb_snd *snd_dev;
+	unsigned long flags;
+
+	snd_dev = gb_find_snd(bundle_id);
+	if (snd_dev)
+		return snd_dev;
+
+	snd_dev = kzalloc(sizeof(*snd_dev), GFP_KERNEL);
+	if (!snd_dev)
+		return NULL;
+
+	spin_lock_init(&snd_dev->lock);
+	snd_dev->device_count = device_count++;
+	snd_dev->gb_bundle_id = bundle_id;
+	spin_lock_irqsave(&gb_snd_list_lock, flags);
+	list_add(&snd_dev->list, &gb_snd_list);
+	spin_unlock_irqrestore(&gb_snd_list_lock, flags);
+	return snd_dev;
+}
+
+static void gb_free_snd(struct gb_snd *snd)
+{
+	unsigned long flags;
+
+	spin_lock_irqsave(&gb_snd_list_lock, flags);
+	if (!snd->i2s_tx_connection &&
+			!snd->mgmt_connection) {
+		list_del(&snd->list);
+		spin_unlock_irqrestore(&gb_snd_list_lock, flags);
+		kfree(snd);
+	} else {
+		spin_unlock_irqrestore(&gb_snd_list_lock, flags);
+	}
+}
+
+
+
+
+/*
+ * This is the ASoC simple card binds the platform codec,
+ * cpu-dai and codec-dai togheter
+ */
+struct gb_card_info_object {
+	struct asoc_simple_card_info card_info;
+	char codec_name[255];
+	char platform_name[255];
+	char dai_name[255];
+};
+
+
+struct asoc_simple_card_info *setup_card_info(int device_count)
+{
+	struct gb_card_info_object *obj;
+
+	obj = kzalloc(sizeof(struct gb_card_info_object), GFP_KERNEL);
+	if (!obj)
+		return NULL;
+
+	obj->card_info.name		= "Greybus Audio Module";
+	obj->card_info.card		= "gb-card";
+	obj->card_info.codec		= obj->codec_name;
+	obj->card_info.platform		= obj->platform_name;
+	obj->card_info.cpu_dai.name	= obj->dai_name;
+	obj->card_info.cpu_dai.fmt	= GB_FMTS;
+#if USE_RT5645
+	obj->card_info.daifmt		= GB_FMTS;
+	sprintf(obj->codec_name, "rt5645.%s", "6-001b"); /* XXX do i2c bus addr dynamically */
+	obj->card_info.codec_dai.name	= "rt5645-aif1";
+	obj->card_info.codec_dai.fmt	= SND_SOC_DAIFMT_CBM_CFM;
+	obj->card_info.codec_dai.sysclk	= 12288000;
+#else
+	sprintf(obj->codec_name, "spdif-dit");
+	obj->card_info.codec_dai.name = "dit-hifi";
+#endif
+	sprintf(obj->platform_name, "gb-pcm-audio.%i", device_count);
+	sprintf(obj->dai_name, "gb-dai-audio.%i", device_count);
+
+	return &obj->card_info;
+}
+
+void free_card_info(struct asoc_simple_card_info *ci)
+{
+	struct gb_card_info_object *obj;
+
+	obj = container_of(ci, struct gb_card_info_object, card_info);
+	kfree(obj);
+}
+
+
+/*
+ * XXX this is sort of cruddy but I get warnings if
+ * we don't have dev.release handler set.
+ */
+static void default_release(struct device *dev)
+{
+}
+
+/*
+ * GB connection hooks
+ */
+static int gb_i2s_transmitter_connection_init(struct gb_connection *connection)
+{
+	struct gb_snd *snd_dev;
+	struct platform_device *codec, *dai;
+	struct asoc_simple_card_info *simple_card;
+	unsigned long flags;
+	int ret;
+
+	snd_dev = gb_get_snd(connection->bundle->id);
+	if (!snd_dev)
+		return -ENOMEM;
+
+	codec = platform_device_register_simple("spdif-dit", -1, NULL, 0);
+	if (!codec) {
+		ret = -ENOMEM;
+		goto out;
+	}
+
+	dai = platform_device_register_simple("gb-pcm-audio", snd_dev->device_count, NULL, 0);
+	if (!dai) {
+		ret = -ENOMEM;
+		goto out;
+	}
+
+	simple_card = setup_card_info(snd_dev->device_count);
+	if (!simple_card) {
+		ret = -ENOMEM;
+		goto out;
+	}
+
+	spin_lock_irqsave(&snd_dev->lock, flags);
+	snd_dev->card.name = "asoc-simple-card";
+	snd_dev->card.id = snd_dev->device_count;
+	snd_dev->card.dev.release = default_release; /* XXX - suspicious */
+
+	snd_dev->cpu_dai.name = "gb-dai-audio";
+	snd_dev->cpu_dai.id = snd_dev->device_count;
+	snd_dev->cpu_dai.dev.release = default_release; /* XXX - suspicious */
+
+
+	snd_dev->simple_card_info = simple_card;
+	snd_dev->card.dev.platform_data = simple_card;
+
+	snd_dev->codec = codec;
+	snd_dev->i2s_tx_connection = connection;
+	snd_dev->cpu_dai.dev.platform_data = snd_dev;
+	snd_dev->i2s_tx_connection->private = snd_dev;
+	spin_unlock_irqrestore(&snd_dev->lock, flags);
+
+	ret = platform_device_register(&snd_dev->cpu_dai);
+	if (ret) {
+		pr_err("cpu_dai platform_device register failed\n");
+		goto out_dai;
+	}
+
+	ret = platform_device_register(&snd_dev->card);
+	if (ret) {
+		pr_err("card platform_device register failed\n");
+		goto out_card;
+	}
+
+	ret = gb_i2s_data_get_version(connection);
+	if (ret) {
+		pr_err("i2s data get_version() failed: %d\n", ret);
+		goto out_get_ver;
+	}
+
+	return 0;
+
+out_get_ver:
+	platform_device_unregister(&snd_dev->card);
+out_card:
+	platform_device_unregister(&snd_dev->cpu_dai);
+out_dai:
+	platform_device_unregister(codec);
+out:
+	gb_free_snd(snd_dev);
+	return ret;
+}
+
+static void gb_i2s_transmitter_connection_exit(struct gb_connection *connection)
+{
+	struct gb_snd *snd_dev;
+
+	snd_dev = (struct gb_snd *)connection->private;
+
+	platform_device_unregister(&snd_dev->card);
+	platform_device_unregister(&snd_dev->cpu_dai);
+	platform_device_unregister(snd_dev->codec);
+
+	free_card_info(snd_dev->simple_card_info);
+	snd_dev->i2s_tx_connection = NULL;
+	gb_free_snd(snd_dev);
+}
+
+static int gb_i2s_mgmt_connection_init(struct gb_connection *connection)
+{
+	struct gb_snd *snd_dev;
+	unsigned long flags;
+	int ret;
+
+	snd_dev = gb_get_snd(connection->bundle->id);
+	if (!snd_dev)
+		return -ENOMEM;
+
+	spin_lock_irqsave(&snd_dev->lock, flags);
+	snd_dev->mgmt_connection = connection;
+	connection->private = snd_dev;
+	spin_unlock_irqrestore(&snd_dev->lock, flags);
+
+	ret = gb_i2s_mgmt_get_version(connection);
+	if (ret) {
+		pr_err("i2s mgmt get_version() failed: %d\n", ret);
+		goto err_free_snd_dev;
+	}
+
+	gb_i2s_mgmt_setup(connection);
+
+	snd_dev->send_data_req_buf = kzalloc(SEND_DATA_BUF_LEN, GFP_KERNEL);
+
+	if (!snd_dev->send_data_req_buf) {
+		ret = -ENOMEM;
+		goto err_deactivate_cport;
+	}
+
+	return 0;
+
+err_deactivate_cport:
+	gb_i2s_mgmt_deactivate_cport(connection, CONFIG_I2S_REMOTE_DATA_CPORT);
+err_free_snd_dev:
+	gb_free_snd(snd_dev);
+	return ret;
+}
+
+static void gb_i2s_mgmt_connection_exit(struct gb_connection *connection)
+{
+	struct gb_snd *snd_dev = (struct gb_snd *)connection->private;
+	int ret;
+
+	ret = gb_i2s_mgmt_deactivate_cport(connection,
+					   CONFIG_I2S_REMOTE_DATA_CPORT);
+	if (ret)
+		pr_err("deactivate_cport failed: %d\n", ret);
+
+	kfree(snd_dev->send_data_req_buf);
+	snd_dev->send_data_req_buf = NULL;
+
+	snd_dev->mgmt_connection = NULL;
+	gb_free_snd(snd_dev);
+}
+
+static int gb_i2s_mgmt_report_event_recv(u8 type, struct gb_operation *op)
+{
+	struct gb_connection *connection = op->connection;
+	struct gb_i2s_mgmt_report_event_request *req = op->request->payload;
+	char *event_name;
+
+	if (type != GB_I2S_MGMT_TYPE_REPORT_EVENT) {
+		dev_err(&connection->dev, "Invalid request type: %d\n",
+			type);
+		return -EINVAL;
+	}
+
+	if (op->request->payload_size < sizeof(*req)) {
+		dev_err(&connection->dev, "Short request received: %d, %d\n",
+			op->request->payload_size, sizeof(*req));
+		return -EINVAL;
+	}
+
+	switch (req->event) {
+	case GB_I2S_MGMT_EVENT_UNSPECIFIED:
+		event_name = "UNSPECIFIED";
+		break;
+	case GB_I2S_MGMT_EVENT_HALT:
+		/* XXX Should stop streaming now */
+		event_name = "HALT";
+		break;
+	case GB_I2S_MGMT_EVENT_INTERNAL_ERROR:
+		event_name = "INTERNAL_ERROR";
+		break;
+	case GB_I2S_MGMT_EVENT_PROTOCOL_ERROR:
+		event_name = "PROTOCOL_ERROR";
+		break;
+	case GB_I2S_MGMT_EVENT_FAILURE:
+		event_name = "FAILURE";
+		break;
+	case GB_I2S_MGMT_EVENT_OUT_OF_SEQUENCE:
+		event_name = "OUT_OF_SEQUENCE";
+		break;
+	case GB_I2S_MGMT_EVENT_UNDERRUN:
+		event_name = "UNDERRUN";
+		break;
+	case GB_I2S_MGMT_EVENT_OVERRUN:
+		event_name = "OVERRUN";
+		break;
+	case GB_I2S_MGMT_EVENT_CLOCKING:
+		event_name = "CLOCKING";
+		break;
+	case GB_I2S_MGMT_EVENT_DATA_LEN:
+		event_name = "DATA_LEN";
+		break;
+	default:
+		dev_warn(&connection->dev, "Unknown I2S Event received: %d\n",
+			 req->event);
+		return -EINVAL;
+	}
+
+	dev_warn(&connection->dev, "I2S Event received: %d - '%s'\n",
+		 req->event, event_name);
+
+	return 0;
+}
+
+static struct gb_protocol gb_i2s_receiver_protocol = {
+	.name			= GB_AUDIO_DATA_DRIVER_NAME,
+	.id			= GREYBUS_PROTOCOL_I2S_RECEIVER,
+	.major			= 0,
+	.minor			= 1,
+	.connection_init	= gb_i2s_transmitter_connection_init,
+	.connection_exit	= gb_i2s_transmitter_connection_exit,
+	.request_recv		= NULL,
+};
+
+static struct gb_protocol gb_i2s_mgmt_protocol = {
+	.name			= GB_AUDIO_MGMT_DRIVER_NAME,
+	.id			= GREYBUS_PROTOCOL_I2S_MGMT,
+	.major			= 0,
+	.minor			= 1,
+	.connection_init	= gb_i2s_mgmt_connection_init,
+	.connection_exit	= gb_i2s_mgmt_connection_exit,
+	.request_recv		= gb_i2s_mgmt_report_event_recv,
+};
+
+
+/*
+ * This is the basic hook get things initialized and registered w/ gb
+ */
+
+int gb_audio_protocol_init(void)
+{
+	int err;
+
+	err = gb_protocol_register(&gb_i2s_mgmt_protocol);
+	if (err) {
+		pr_err("Can't register i2s mgmt protocol driver: %d\n", -err);
+		return err;
+	}
+
+	err = gb_protocol_register(&gb_i2s_receiver_protocol);
+	if (err) {
+		pr_err("Can't register Audio protocol driver: %d\n", -err);
+		goto err_unregister_i2s_mgmt;
+	}
+
+	err = platform_driver_register(&gb_audio_plat_driver);
+	if (err) {
+		pr_err("Can't register platform driver: %d\n", -err);
+		goto err_unregister_plat;
+	}
+
+	err = platform_driver_register(&gb_audio_pcm_driver);
+	if (err) {
+		pr_err("Can't register pcm driver: %d\n", -err);
+		goto err_unregister_pcm;
+	}
+
+	return 0;
+
+err_unregister_pcm:
+	platform_driver_unregister(&gb_audio_plat_driver);
+err_unregister_plat:
+	gb_protocol_deregister(&gb_i2s_receiver_protocol);
+err_unregister_i2s_mgmt:
+	gb_protocol_deregister(&gb_i2s_mgmt_protocol);
+	return err;
+}
+
+void gb_audio_protocol_exit(void)
+{
+	platform_driver_unregister(&gb_audio_pcm_driver);
+	platform_driver_unregister(&gb_audio_plat_driver);
+	gb_protocol_deregister(&gb_i2s_receiver_protocol);
+	gb_protocol_deregister(&gb_i2s_mgmt_protocol);
+}
+
+
+MODULE_LICENSE("GPL");
diff --git a/audio.h b/audio.h
new file mode 100644
index 0000000..6a337d1
--- /dev/null
+++ b/audio.h
@@ -0,0 +1,100 @@ 
+#ifndef __GB_AUDIO_H
+#define __GB_AUDIO_H
+#include <linux/kernel.h>
+#include <linux/device.h>
+#include <linux/interrupt.h>
+#include <linux/module.h>
+#include <linux/platform_device.h>
+#include <sound/soc.h>
+#include "greybus.h"
+#include "gpbridge.h"
+
+
+#define GB_SAMPLE_RATE				48000
+#define GB_RATES				SNDRV_PCM_RATE_48000
+#define GB_FMTS					SNDRV_PCM_FMTBIT_S16_LE
+#define PREALLOC_BUFFER				(32 * 1024)
+#define PREALLOC_BUFFER_MAX			(32 * 1024)
+
+/* assuming 1 ms samples @ 48KHz */
+#define CONFIG_SAMPLES_PER_MSG			48L
+#define CONFIG_PERIOD_NS			1000000 /* send msg every 1ms */
+
+#define CONFIG_COUNT_MAX			32
+#define CONFIG_I2S_REMOTE_DATA_CPORT		7 /* XXX shouldn't be hardcoded...*/
+#define RT5647_SLAVE_ADDR			0x1b /* from toshiba/quanta code */
+
+/* Switch between dummy spdif and jetson rt5645 codec */
+#define USE_RT5645				0
+
+#define SAMPLE_SIZE				4
+#define MAX_SEND_DATA_LEN (CONFIG_SAMPLES_PER_MSG * SAMPLE_SIZE)
+#define SEND_DATA_BUF_LEN (sizeof(struct gb_i2s_send_data_request) + \
+				MAX_SEND_DATA_LEN)
+
+
+/*
+ * This is the gb_snd structure which ties everything together
+ * and fakes DMA interrupts via a timer.
+ */
+struct gb_snd {
+	struct platform_device		card;
+	struct platform_device		cpu_dai;
+	struct platform_device		*codec;
+	struct asoc_simple_card_info	*simple_card_info;
+	struct gb_connection		*mgmt_connection;
+	struct gb_connection		*i2s_tx_connection;
+	struct gb_connection		*i2s_rx_connection;
+	char				*send_data_req_buf;
+	long				send_data_sample_count;
+	int				gb_bundle_id;
+	int				device_count;
+	struct snd_pcm_substream	*substream;
+	struct hrtimer			timer;
+	atomic_t			running;
+	struct workqueue_struct		*workqueue;
+	struct work_struct		work;
+	int				hwptr_done;
+	int				transfer_done;
+	struct list_head		list;
+	spinlock_t			lock;
+};
+
+
+/*
+ * GB I2S cmd functions
+ */
+int gb_i2s_mgmt_get_version(struct gb_connection *connection);
+int gb_i2s_data_get_version(struct gb_connection *connection);
+int gb_i2s_mgmt_activate_cport(struct gb_connection *connection,
+				      uint16_t cport);
+int gb_i2s_mgmt_deactivate_cport(struct gb_connection *connection,
+					uint16_t cport);
+int gb_i2s_mgmt_get_supported_configurations(
+	struct gb_connection *connection,
+	struct gb_i2s_mgmt_get_supported_configurations_response *get_cfg,
+	size_t size);
+int gb_i2s_mgmt_set_configuration(struct gb_connection *connection,
+			struct gb_i2s_mgmt_set_configuration_request *set_cfg);
+int gb_i2s_mgmt_set_samples_per_message(struct gb_connection *connection,
+					uint16_t samples_per_message);
+int gb_i2s_mgmt_setup(struct gb_connection *connection);
+int gb_i2s_send_data(struct gb_connection *connection, void *req_buf,
+				void *source_addr, size_t len, int sample_num);
+
+
+/*
+ * GB PCM hooks
+ */
+void gb_pcm_hrtimer_start(struct gb_snd *snd_dev);
+void gb_pcm_hrtimer_stop(struct gb_snd *snd_dev);
+
+
+/*
+ * Platform drivers
+ */
+extern struct platform_driver gb_audio_pcm_driver;
+extern struct platform_driver gb_audio_plat_driver;
+
+
+#endif /* __GB_AUDIO_H */
diff --git a/gpb.c b/gpb.c
index d5747b2..2324270 100644
--- a/gpb.c
+++ b/gpb.c
@@ -53,8 +53,15 @@  static int __init gpbridge_init(void)
 		pr_err("error initializing hid protocol\n");
 		goto error_hid;
 	}
+	if (gb_audio_protocol_init()) {
+		pr_err("error initializing audio protocols\n");
+		goto error_audio;
+	}
+
 	return 0;
 
+error_audio:
+	gb_hid_protocol_exit();
 error_hid:
 	gb_spi_protocol_exit();
 error_spi:
@@ -76,6 +83,7 @@  module_init(gpbridge_init);
 
 static void __exit gpbridge_exit(void)
 {
+	gb_audio_protocol_exit();
 	gb_hid_protocol_exit();
 	gb_spi_protocol_exit();
 	gb_i2c_protocol_exit();
diff --git a/gpbridge.h b/gpbridge.h
index 85d8019..85cc385 100644
--- a/gpbridge.h
+++ b/gpbridge.h
@@ -341,6 +341,7 @@  struct gb_i2s_mgmt_configuration {
 	__u8	pad;
 	__le32	spatial_locations;
 	__le32	ll_protocol;
+	__u8	ll_mclk_role;
 	__u8	ll_bclk_role;
 	__u8	ll_wclk_role;
 	__u8	ll_wclk_polarity;
@@ -348,7 +349,6 @@  struct gb_i2s_mgmt_configuration {
 	__u8	ll_wclk_tx_edge;
 	__u8	ll_wclk_rx_edge;
 	__u8	ll_data_offset;
-	__u8	ll_pad;
 };
 
 /* get supported configurations request has no payload */
diff --git a/protocol.h b/protocol.h
index 495d13a..7958802 100644
--- a/protocol.h
+++ b/protocol.h
@@ -87,6 +87,9 @@  extern void gb_spi_protocol_exit(void);
 extern int gb_hid_protocol_init(void);
 extern void gb_hid_protocol_exit(void);
 
+extern int gb_audio_protocol_init(void);
+extern void gb_audio_protocol_exit(void);
+
 #define gb_protocol_driver(__protocol)			\
 static int __init protocol_init(void)			\
 {							\