staging: bcm2835-audio: initial staging submission

Initial cleanup of bcm2835-audio driver for the
bcm2535(Raspberry PI)

Driver provides HDMI audio through ALSA and is built
on top of the vc04_services driver.

Original version of the driver is available at:
http://www.github.com/raspberry/linux

Driver compiles without any build errors or warnings.

Tested on a RPI 3 running in ARM64 mode with the
vlc player and alsautils.

Signed-off-by: Michael Zoran <mzoran@crowfest.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

1 files changed, 903 insertions, 0 deletions

diff --git a/drivers/staging/bcm2835-audio/bcm2835-vchiq.c b/drivers/staging/bcm2835-audio/bcm2835-vchiq.c
new file mode 100644
index 0000000..af70c27
--- /dev/null
+++ b/drivers/staging/bcm2835-audio/bcm2835-vchiq.c
@@ -0,0 +1,903 @@
+/*****************************************************************************
+ * Copyright 2011 Broadcom Corporation.  All rights reserved.
+ *
+ * Unless you and Broadcom execute a separate written software license
+ * agreement governing use of this software, this software is licensed to you
+ * under the terms of the GNU General Public License version 2, available at
+ * http://www.broadcom.com/licenses/GPLv2.php (the "GPL").
+ *
+ * Notwithstanding the above, under no circumstances may you combine this
+ * software in any way with any other Broadcom software provided under a
+ * license other than the GPL, without Broadcom's express prior written
+ * consent.
+ *****************************************************************************/
+
+#include <linux/device.h>
+#include <sound/core.h>
+#include <sound/initval.h>
+#include <sound/pcm.h>
+#include <linux/io.h>
+#include <linux/interrupt.h>
+#include <linux/fs.h>
+#include <linux/file.h>
+#include <linux/mm.h>
+#include <linux/syscalls.h>
+#include <asm/uaccess.h>
+#include <linux/slab.h>
+#include <linux/delay.h>
+#include <linux/atomic.h>
+#include <linux/module.h>
+#include <linux/completion.h>
+
+#include "bcm2835.h"
+
+/* ---- Include Files -------------------------------------------------------- */
+
+#include "interface/vchi/vchi.h"
+#include "vc_vchi_audioserv_defs.h"
+
+/* ---- Private Constants and Types ------------------------------------------ */
+
+#define BCM2835_AUDIO_STOP           0
+#define BCM2835_AUDIO_START          1
+#define BCM2835_AUDIO_WRITE          2
+
+/* Logging macros (for remapping to other logging mechanisms, i.e., printf) */
+#ifdef AUDIO_DEBUG_ENABLE
+#define LOG_ERR( fmt, arg... )   pr_err( "%s:%d " fmt, __func__, __LINE__, ##arg)
+#define LOG_WARN( fmt, arg... )  pr_info( "%s:%d " fmt, __func__, __LINE__, ##arg)
+#define LOG_INFO( fmt, arg... )  pr_info( "%s:%d " fmt, __func__, __LINE__, ##arg)
+#define LOG_DBG( fmt, arg... )   pr_info( "%s:%d " fmt, __func__, __LINE__, ##arg)
+#else
+#define LOG_ERR( fmt, arg... )   pr_err( "%s:%d " fmt, __func__, __LINE__, ##arg)
+#define LOG_WARN( fmt, arg... )
+#define LOG_INFO( fmt, arg... )
+#define LOG_DBG( fmt, arg... )
+#endif
+
+struct bcm2835_audio_instance {
+	unsigned int num_connections;
+	VCHI_SERVICE_HANDLE_T vchi_handle[VCHI_MAX_NUM_CONNECTIONS];
+	struct completion msg_avail_comp;
+	struct mutex vchi_mutex;
+	struct bcm2835_alsa_stream *alsa_stream;
+	int result;
+	short peer_version;
+};
+
+bool force_bulk = false;
+
+/* ---- Private Variables ---------------------------------------------------- */
+
+/* ---- Private Function Prototypes ------------------------------------------ */
+
+/* ---- Private Functions ---------------------------------------------------- */
+
+static int bcm2835_audio_stop_worker(struct bcm2835_alsa_stream *alsa_stream);
+static int bcm2835_audio_start_worker(struct bcm2835_alsa_stream *alsa_stream);
+static int bcm2835_audio_write_worker(struct bcm2835_alsa_stream *alsa_stream,
+				      unsigned int count, void *src);
+
+
+// Routine to send a message across a service
+
+static ssize_t
+bcm2835_vchi_msg_queue_callback(void *context, void *dest,
+				size_t offset, size_t maxsize)
+{
+	memcpy(dest, context + offset, maxsize);
+	return maxsize;
+}
+
+static int
+bcm2835_vchi_msg_queue(VCHI_SERVICE_HANDLE_T handle,
+		       void *data,
+		       unsigned int size)
+{
+	return vchi_msg_queue(handle,
+			      bcm2835_vchi_msg_queue_callback,
+			      data,
+			      size);
+}
+
+struct bcm2835_audio_work {
+	struct work_struct my_work;
+	struct bcm2835_alsa_stream *alsa_stream;
+	int cmd;
+	void *src;
+	unsigned int count;
+};
+
+static void my_wq_function(struct work_struct *work)
+{
+	struct bcm2835_audio_work *w =
+		container_of(work, struct bcm2835_audio_work, my_work);
+	int ret = -9;
+	LOG_DBG(" .. IN %p:%d\n", w->alsa_stream, w->cmd);
+	switch (w->cmd) {
+	case BCM2835_AUDIO_START:
+		ret = bcm2835_audio_start_worker(w->alsa_stream);
+		break;
+	case BCM2835_AUDIO_STOP:
+		ret = bcm2835_audio_stop_worker(w->alsa_stream);
+		break;
+	case BCM2835_AUDIO_WRITE:
+		ret = bcm2835_audio_write_worker(w->alsa_stream, w->count,
+						 w->src);
+		break;
+	default:
+		LOG_ERR(" Unexpected work: %p:%d\n", w->alsa_stream, w->cmd);
+		break;
+	}
+	kfree((void *) work);
+	LOG_DBG(" .. OUT %d\n", ret);
+}
+
+int bcm2835_audio_start(struct bcm2835_alsa_stream *alsa_stream)
+{
+	int ret = -1;
+	LOG_DBG(" .. IN\n");
+	if (alsa_stream->my_wq) {
+		struct bcm2835_audio_work *work =
+			kmalloc(sizeof(struct bcm2835_audio_work *), GFP_ATOMIC);
+		/*--- Queue some work (item 1) ---*/
+		if (work) {
+			INIT_WORK(&work->my_work, my_wq_function);
+			work->alsa_stream = alsa_stream;
+			work->cmd = BCM2835_AUDIO_START;
+			if (queue_work(alsa_stream->my_wq, &work->my_work))
+				ret = 0;
+		} else
+			LOG_ERR(" .. Error: NULL work kmalloc\n");
+	}
+	LOG_DBG(" .. OUT %d\n", ret);
+	return ret;
+}
+
+int bcm2835_audio_stop(struct bcm2835_alsa_stream *alsa_stream)
+{
+	int ret = -1;
+	LOG_DBG(" .. IN\n");
+	if (alsa_stream->my_wq) {
+		struct bcm2835_audio_work *work =
+			kmalloc(sizeof(struct bcm2835_audio_work *), GFP_ATOMIC);
+		/*--- Queue some work (item 1) ---*/
+		if (work) {
+			INIT_WORK(&work->my_work, my_wq_function);
+			work->alsa_stream = alsa_stream;
+			work->cmd = BCM2835_AUDIO_STOP;
+			if (queue_work(alsa_stream->my_wq, &work->my_work))
+				ret = 0;
+		} else
+			LOG_ERR(" .. Error: NULL work kmalloc\n");
+	}
+	LOG_DBG(" .. OUT %d\n", ret);
+	return ret;
+}
+
+int bcm2835_audio_write(struct bcm2835_alsa_stream *alsa_stream,
+			unsigned int count, void *src)
+{
+	int ret = -1;
+	LOG_DBG(" .. IN\n");
+	if (alsa_stream->my_wq) {
+		struct bcm2835_audio_work *work =
+			kmalloc(sizeof(struct bcm2835_audio_work *), GFP_ATOMIC);
+		/*--- Queue some work (item 1) ---*/
+		if (work) {
+			INIT_WORK(&work->my_work, my_wq_function);
+			work->alsa_stream = alsa_stream;
+			work->cmd = BCM2835_AUDIO_WRITE;
+			work->src = src;
+			work->count = count;
+			if (queue_work(alsa_stream->my_wq, &work->my_work))
+				ret = 0;
+		} else
+			LOG_ERR(" .. Error: NULL work kmalloc\n");
+	}
+	LOG_DBG(" .. OUT %d\n", ret);
+	return ret;
+}
+
+void my_workqueue_init(struct bcm2835_alsa_stream *alsa_stream)
+{
+	alsa_stream->my_wq = alloc_workqueue("my_queue", WQ_HIGHPRI, 1);
+	return;
+}
+
+void my_workqueue_quit(struct bcm2835_alsa_stream *alsa_stream)
+{
+	if (alsa_stream->my_wq) {
+		flush_workqueue(alsa_stream->my_wq);
+		destroy_workqueue(alsa_stream->my_wq);
+		alsa_stream->my_wq = NULL;
+	}
+	return;
+}
+
+static void audio_vchi_callback(void *param,
+				const VCHI_CALLBACK_REASON_T reason,
+				void *msg_handle)
+{
+	struct bcm2835_audio_instance *instance = param;
+	int status;
+	int msg_len;
+	struct vc_audio_msg m;
+	LOG_DBG(" .. IN instance=%p, handle=%p, alsa=%p, reason=%d, handle=%p\n",
+		instance, instance ? instance->vchi_handle[0] : NULL, instance ? instance->alsa_stream : NULL, reason, msg_handle);
+
+	if (reason != VCHI_CALLBACK_MSG_AVAILABLE) {
+		return;
+	}
+	if (!instance) {
+		LOG_ERR(" .. instance is null\n");
+		BUG();
+		return;
+	}
+	if (!instance->vchi_handle[0]) {
+		LOG_ERR(" .. instance->vchi_handle[0] is null\n");
+		BUG();
+		return;
+	}
+	status = vchi_msg_dequeue(instance->vchi_handle[0],
+				  &m, sizeof(m), &msg_len, VCHI_FLAGS_NONE);
+	if (m.type == VC_AUDIO_MSG_TYPE_RESULT) {
+		LOG_DBG(" .. instance=%p, m.type=VC_AUDIO_MSG_TYPE_RESULT, success=%d\n",
+			instance, m.u.result.success);
+		instance->result = m.u.result.success;
+		complete(&instance->msg_avail_comp);
+	} else if (m.type == VC_AUDIO_MSG_TYPE_COMPLETE) {
+		struct bcm2835_alsa_stream *alsa_stream = instance->alsa_stream;
+#if defined(CONFIG_64BIT)
+		irq_handler_t callback =
+			(irq_handler_t) (((unsigned long) m.u.complete.callbackl) |
+			((unsigned long) m.u.complete.callbackh << 32));
+#else
+		irq_handler_t callback = (irq_handler_t) m.u.complete.callback;
+#endif
+		LOG_DBG(" .. instance=%p, m.type=VC_AUDIO_MSG_TYPE_COMPLETE, complete=%d\n",
+			instance, m.u.complete.count);
+		if (alsa_stream && callback) {
+			atomic_add(m.u.complete.count, &alsa_stream->retrieved);
+			callback(0, alsa_stream);
+		} else {
+			LOG_ERR(" .. unexpected alsa_stream=%p, callback=%p\n",
+				alsa_stream, callback);
+		}
+	} else {
+		LOG_ERR(" .. unexpected m.type=%d\n", m.type);
+	}
+	LOG_DBG(" .. OUT\n");
+}
+
+static struct bcm2835_audio_instance *
+vc_vchi_audio_init(VCHI_INSTANCE_T vchi_instance,
+		   VCHI_CONNECTION_T **vchi_connections,
+		   unsigned int num_connections)
+{
+	unsigned int i;
+	struct bcm2835_audio_instance *instance;
+	int status;
+
+	LOG_DBG("%s: start", __func__);
+
+	if (num_connections > VCHI_MAX_NUM_CONNECTIONS) {
+		LOG_ERR("%s: unsupported number of connections %u (max=%u)\n",
+			__func__, num_connections, VCHI_MAX_NUM_CONNECTIONS);
+
+		return NULL;
+	}
+	/* Allocate memory for this instance */
+	instance = kmalloc(sizeof(*instance), GFP_KERNEL);
+	if (!instance)
+		return NULL;
+
+	memset(instance, 0, sizeof(*instance));
+	instance->num_connections = num_connections;
+
+	/* Create a lock for exclusive, serialized VCHI connection access */
+	mutex_init(&instance->vchi_mutex);
+	/* Open the VCHI service connections */
+	for (i = 0; i < num_connections; i++) {
+		SERVICE_CREATION_T params = {
+			VCHI_VERSION_EX(VC_AUDIOSERV_VER, VC_AUDIOSERV_MIN_VER),
+			VC_AUDIO_SERVER_NAME, // 4cc service code
+			vchi_connections[i], // passed in fn pointers
+			0, // rx fifo size (unused)
+			0, // tx fifo size (unused)
+			audio_vchi_callback, // service callback
+			instance, // service callback parameter
+			1, //TODO: remove VCOS_FALSE,   // unaligned bulk recieves
+			1, //TODO: remove VCOS_FALSE,   // unaligned bulk transmits
+			0 // want crc check on bulk transfers
+		};
+
+		LOG_DBG("%s: about to open %i\n", __func__, i);
+		status = vchi_service_open(vchi_instance, &params,
+			&instance->vchi_handle[i]);
+		LOG_DBG("%s: opened %i: %p=%d\n", __func__, i, instance->vchi_handle[i], status);
+		if (status) {
+			LOG_ERR("%s: failed to open VCHI service connection (status=%d)\n",
+				__func__, status);
+
+			goto err_close_services;
+		}
+		/* Finished with the service for now */
+		vchi_service_release(instance->vchi_handle[i]);
+	}
+
+	LOG_DBG("%s: okay\n", __func__);
+	return instance;
+
+err_close_services:
+	for (i = 0; i < instance->num_connections; i++) {
+		LOG_ERR("%s: closing %i: %p\n", __func__, i, instance->vchi_handle[i]);
+		if (instance->vchi_handle[i])
+			vchi_service_close(instance->vchi_handle[i]);
+	}
+
+	kfree(instance);
+	LOG_ERR("%s: error\n", __func__);
+
+	return NULL;
+}
+
+static int vc_vchi_audio_deinit(struct bcm2835_audio_instance *instance)
+{
+	unsigned int i;
+
+	LOG_DBG(" .. IN\n");
+
+	if (!instance) {
+		LOG_ERR("%s: invalid handle %p\n", __func__, instance);
+
+		return -1;
+	}
+
+	LOG_DBG(" .. about to lock (%d)\n", instance->num_connections);
+	if (mutex_lock_interruptible(&instance->vchi_mutex)) {
+		LOG_DBG("Interrupted whilst waiting for lock on (%d)\n",
+			instance->num_connections);
+		return -EINTR;
+	}
+
+	/* Close all VCHI service connections */
+	for (i = 0; i < instance->num_connections; i++) {
+		int status;
+		LOG_DBG(" .. %i:closing %p\n", i, instance->vchi_handle[i]);
+		vchi_service_use(instance->vchi_handle[i]);
+
+		status = vchi_service_close(instance->vchi_handle[i]);
+		if (status) {
+			LOG_DBG("%s: failed to close VCHI service connection (status=%d)\n",
+				__func__, status);
+		}
+	}
+
+	mutex_unlock(&instance->vchi_mutex);
+
+	kfree(instance);
+
+	LOG_DBG(" .. OUT\n");
+
+	return 0;
+}
+
+static int bcm2835_audio_open_connection(struct bcm2835_alsa_stream *alsa_stream)
+{
+	static VCHI_INSTANCE_T vchi_instance;
+	static VCHI_CONNECTION_T *vchi_connection;
+	static int initted;
+	struct bcm2835_audio_instance *instance =
+		(struct bcm2835_audio_instance *)alsa_stream->instance;
+	int ret;
+	LOG_DBG(" .. IN\n");
+
+	LOG_INFO("%s: start\n", __func__);
+	BUG_ON(instance);
+	if (instance) {
+		LOG_ERR("%s: VCHI instance already open (%p)\n",
+			__func__, instance);
+		instance->alsa_stream = alsa_stream;
+		alsa_stream->instance = instance;
+		ret = 0; // xxx todo -1;
+		goto err_free_mem;
+	}
+
+	/* Initialize and create a VCHI connection */
+	if (!initted) {
+		ret = vchi_initialise(&vchi_instance);
+		if (ret) {
+			LOG_ERR("%s: failed to initialise VCHI instance (ret=%d)\n",
+				__func__, ret);
+
+			ret = -EIO;
+			goto err_free_mem;
+		}
+		ret = vchi_connect(NULL, 0, vchi_instance);
+		if (ret) {
+			LOG_ERR("%s: failed to connect VCHI instance (ret=%d)\n",
+				__func__, ret);
+
+			ret = -EIO;
+			goto err_free_mem;
+		}
+		initted = 1;
+	}
+
+	/* Initialize an instance of the audio service */
+	instance = vc_vchi_audio_init(vchi_instance, &vchi_connection, 1);
+
+	if (!instance) {
+		LOG_ERR("%s: failed to initialize audio service\n", __func__);
+
+		ret = -EPERM;
+		goto err_free_mem;
+	}
+
+	instance->alsa_stream = alsa_stream;
+	alsa_stream->instance = instance;
+
+	LOG_DBG(" success !\n");
+err_free_mem:
+	LOG_DBG(" .. OUT\n");
+
+	return ret;
+}
+
+int bcm2835_audio_open(struct bcm2835_alsa_stream *alsa_stream)
+{
+	struct bcm2835_audio_instance *instance;
+	struct vc_audio_msg m;
+	int status;
+	int ret;
+	LOG_DBG(" .. IN\n");
+
+	my_workqueue_init(alsa_stream);
+
+	ret = bcm2835_audio_open_connection(alsa_stream);
+	if (ret) {
+		ret = -1;
+		goto exit;
+	}
+	instance = alsa_stream->instance;
+	LOG_DBG(" instance (%p)\n", instance);
+
+	if (mutex_lock_interruptible(&instance->vchi_mutex)) {
+		LOG_DBG("Interrupted whilst waiting for lock on (%d)\n", instance->num_connections);
+		return -EINTR;
+	}
+	vchi_service_use(instance->vchi_handle[0]);
+
+	m.type = VC_AUDIO_MSG_TYPE_OPEN;
+
+	/* Send the message to the videocore */
+	status = bcm2835_vchi_msg_queue(instance->vchi_handle[0],
+					&m, sizeof(m));
+
+	if (status) {
+		LOG_ERR("%s: failed on vchi_msg_queue (status=%d)\n",
+			__func__, status);
+
+		ret = -1;
+		goto unlock;
+	}
+
+	ret = 0;
+
+unlock:
+	vchi_service_release(instance->vchi_handle[0]);
+	mutex_unlock(&instance->vchi_mutex);
+exit:
+	LOG_DBG(" .. OUT\n");
+	return ret;
+}
+
+static int bcm2835_audio_set_ctls_chan(struct bcm2835_alsa_stream *alsa_stream,
+				       struct bcm2835_chip *chip)
+{
+	struct vc_audio_msg m;
+	struct bcm2835_audio_instance *instance = alsa_stream->instance;
+	int status;
+	int ret;
+	LOG_DBG(" .. IN\n");
+
+	LOG_INFO(" Setting ALSA dest(%d), volume(%d)\n",
+		 chip->dest, chip->volume);
+
+	if (mutex_lock_interruptible(&instance->vchi_mutex)) {
+		LOG_DBG("Interrupted whilst waiting for lock on (%d)\n",
+			instance->num_connections);
+		return -EINTR;
+	}
+	vchi_service_use(instance->vchi_handle[0]);
+
+	instance->result = -1;
+
+	m.type = VC_AUDIO_MSG_TYPE_CONTROL;
+	m.u.control.dest = chip->dest;
+	m.u.control.volume = chip->volume;
+
+	/* Create the message available completion */
+	init_completion(&instance->msg_avail_comp);
+
+	/* Send the message to the videocore */
+	status = bcm2835_vchi_msg_queue(instance->vchi_handle[0],
+					&m, sizeof(m));
+
+	if (status) {
+		LOG_ERR("%s: failed on vchi_msg_queue (status=%d)\n",
+			__func__, status);
+
+		ret = -1;
+		goto unlock;
+	}
+
+	/* We are expecting a reply from the videocore */
+	wait_for_completion(&instance->msg_avail_comp);
+
+	if (instance->result) {
+		LOG_ERR("%s: result=%d\n", __func__, instance->result);
+
+		ret = -1;
+		goto unlock;
+	}
+
+	ret = 0;
+
+unlock:
+	vchi_service_release(instance->vchi_handle[0]);
+	mutex_unlock(&instance->vchi_mutex);
+
+	LOG_DBG(" .. OUT\n");
+	return ret;
+}
+
+int bcm2835_audio_set_ctls(struct bcm2835_chip *chip)
+{
+	int i;
+	int ret = 0;
+	LOG_DBG(" .. IN\n");
+	LOG_DBG(" Setting ALSA dest(%d), volume(%d)\n", chip->dest, chip->volume);
+
+	/* change ctls for all substreams */
+	for (i = 0; i < MAX_SUBSTREAMS; i++) {
+		if (chip->avail_substreams & (1 << i)) {
+			if (!chip->alsa_stream[i]) {
+				LOG_DBG(" No ALSA stream available?! %i:%p (%x)\n", i, chip->alsa_stream[i], chip->avail_substreams);
+				ret = 0;
+			} else if (bcm2835_audio_set_ctls_chan(chip->alsa_stream[i], chip) != 0) {
+				LOG_ERR("Couldn't set the controls for stream %d\n", i);
+				ret = -1;
+			} else LOG_DBG(" Controls set for stream %d\n", i);
+		}
+	}
+	LOG_DBG(" .. OUT ret=%d\n", ret);
+	return ret;
+}
+
+int bcm2835_audio_set_params(struct bcm2835_alsa_stream *alsa_stream,
+			     unsigned int channels, unsigned int samplerate,
+			     unsigned int bps)
+{
+	struct vc_audio_msg m;
+	struct bcm2835_audio_instance *instance = alsa_stream->instance;
+	int status;
+	int ret;
+	LOG_DBG(" .. IN\n");
+
+	LOG_INFO(" Setting ALSA channels(%d), samplerate(%d), bits-per-sample(%d)\n",
+		channels, samplerate, bps);
+
+	/* resend ctls - alsa_stream may not have been open when first send */
+	ret = bcm2835_audio_set_ctls_chan(alsa_stream, alsa_stream->chip);
+	if (ret) {
+		LOG_ERR(" Alsa controls not supported\n");
+		return -EINVAL;
+	}
+
+	if (mutex_lock_interruptible(&instance->vchi_mutex)) {
+		LOG_DBG("Interrupted whilst waiting for lock on (%d)\n", instance->num_connections);
+		return -EINTR;
+	}
+	vchi_service_use(instance->vchi_handle[0]);
+
+	instance->result = -1;
+
+	m.type = VC_AUDIO_MSG_TYPE_CONFIG;
+	m.u.config.channels = channels;
+	m.u.config.samplerate = samplerate;
+	m.u.config.bps = bps;
+
+	/* Create the message available completion */
+	init_completion(&instance->msg_avail_comp);
+
+	/* Send the message to the videocore */
+	status = bcm2835_vchi_msg_queue(instance->vchi_handle[0],
+					&m, sizeof(m));
+
+	if (status) {
+		LOG_ERR("%s: failed on vchi_msg_queue (status=%d)\n",
+			__func__, status);
+
+		ret = -1;
+		goto unlock;
+	}
+
+	/* We are expecting a reply from the videocore */
+	wait_for_completion(&instance->msg_avail_comp);
+
+	if (instance->result) {
+		LOG_ERR("%s: result=%d", __func__, instance->result);
+
+		ret = -1;
+		goto unlock;
+	}
+
+	ret = 0;
+
+unlock:
+	vchi_service_release(instance->vchi_handle[0]);
+	mutex_unlock(&instance->vchi_mutex);
+
+	LOG_DBG(" .. OUT\n");
+	return ret;
+}
+
+int bcm2835_audio_setup(struct bcm2835_alsa_stream *alsa_stream)
+{
+	LOG_DBG(" .. IN\n");
+
+	LOG_DBG(" .. OUT\n");
+
+	return 0;
+}
+
+static int bcm2835_audio_start_worker(struct bcm2835_alsa_stream *alsa_stream)
+{
+	struct vc_audio_msg m;
+	struct bcm2835_audio_instance *instance = alsa_stream->instance;
+	int status;
+	int ret;
+	LOG_DBG(" .. IN\n");
+
+	if (mutex_lock_interruptible(&instance->vchi_mutex)) {
+		LOG_DBG("Interrupted whilst waiting for lock on (%d)\n",
+			instance->num_connections);
+		return -EINTR;
+	}
+	vchi_service_use(instance->vchi_handle[0]);
+
+	m.type = VC_AUDIO_MSG_TYPE_START;
+
+	/* Send the message to the videocore */
+	status = bcm2835_vchi_msg_queue(instance->vchi_handle[0],
+					&m, sizeof(m));
+
+	if (status) {
+		LOG_ERR("%s: failed on vchi_msg_queue (status=%d)\n",
+			__func__, status);
+
+		ret = -1;
+		goto unlock;
+	}
+
+	ret = 0;
+
+unlock:
+	vchi_service_release(instance->vchi_handle[0]);
+	mutex_unlock(&instance->vchi_mutex);
+	LOG_DBG(" .. OUT\n");
+	return ret;
+}
+
+static int bcm2835_audio_stop_worker(struct bcm2835_alsa_stream *alsa_stream)
+{
+	struct vc_audio_msg m;
+	struct bcm2835_audio_instance *instance = alsa_stream->instance;
+	int status;
+	int ret;
+	LOG_DBG(" .. IN\n");
+
+	if (mutex_lock_interruptible(&instance->vchi_mutex)) {
+		LOG_DBG("Interrupted whilst waiting for lock on (%d)\n",
+			instance->num_connections);
+		return -EINTR;
+	}
+	vchi_service_use(instance->vchi_handle[0]);
+
+	m.type = VC_AUDIO_MSG_TYPE_STOP;
+	m.u.stop.draining = alsa_stream->draining;
+
+	/* Send the message to the videocore */
+	status = bcm2835_vchi_msg_queue(instance->vchi_handle[0],
+					&m, sizeof(m));
+
+	if (status) {
+		LOG_ERR("%s: failed on vchi_msg_queue (status=%d)\n",
+			__func__, status);
+
+		ret = -1;
+		goto unlock;
+	}
+
+	ret = 0;
+
+unlock:
+	vchi_service_release(instance->vchi_handle[0]);
+	mutex_unlock(&instance->vchi_mutex);
+	LOG_DBG(" .. OUT\n");
+	return ret;
+}
+
+int bcm2835_audio_close(struct bcm2835_alsa_stream *alsa_stream)
+{
+	struct vc_audio_msg m;
+	struct bcm2835_audio_instance *instance = alsa_stream->instance;
+	int status;
+	int ret;
+	LOG_DBG(" .. IN\n");
+
+	my_workqueue_quit(alsa_stream);
+
+	if (mutex_lock_interruptible(&instance->vchi_mutex)) {
+		LOG_DBG("Interrupted whilst waiting for lock on (%d)\n",
+			instance->num_connections);
+		return -EINTR;
+	}
+	vchi_service_use(instance->vchi_handle[0]);
+
+	m.type = VC_AUDIO_MSG_TYPE_CLOSE;
+
+	/* Create the message available completion */
+	init_completion(&instance->msg_avail_comp);
+
+	/* Send the message to the videocore */
+	status = bcm2835_vchi_msg_queue(instance->vchi_handle[0],
+					&m, sizeof(m));
+
+	if (status) {
+		LOG_ERR("%s: failed on vchi_msg_queue (status=%d)\n",
+			__func__, status);
+		ret = -1;
+		goto unlock;
+	}
+
+	/* We are expecting a reply from the videocore */
+	wait_for_completion(&instance->msg_avail_comp);
+
+	if (instance->result) {
+		LOG_ERR("%s: failed result (result=%d)\n",
+			__func__, instance->result);
+
+		ret = -1;
+		goto unlock;
+	}
+
+	ret = 0;
+
+unlock:
+	vchi_service_release(instance->vchi_handle[0]);
+	mutex_unlock(&instance->vchi_mutex);
+
+	/* Stop the audio service */
+	if (instance) {
+		vc_vchi_audio_deinit(instance);
+		alsa_stream->instance = NULL;
+	}
+	LOG_DBG(" .. OUT\n");
+	return ret;
+}
+
+int bcm2835_audio_write_worker(struct bcm2835_alsa_stream *alsa_stream,
+			       unsigned int count, void *src)
+{
+	struct vc_audio_msg m;
+	struct bcm2835_audio_instance *instance = alsa_stream->instance;
+	int status;
+	int ret;
+
+	LOG_DBG(" .. IN\n");
+
+	LOG_INFO(" Writing %d bytes from %p\n", count, src);
+
+	if (mutex_lock_interruptible(&instance->vchi_mutex)) {
+		LOG_DBG("Interrupted whilst waiting for lock on (%d)\n",
+			instance->num_connections);
+		return -EINTR;
+	}
+	vchi_service_use(instance->vchi_handle[0]);
+
+	if (instance->peer_version == 0 && vchi_get_peer_version(instance->vchi_handle[0], &instance->peer_version) == 0) {
+		LOG_DBG("%s: client version %d connected\n", __func__, instance->peer_version);
+	}
+	m.type = VC_AUDIO_MSG_TYPE_WRITE;
+	m.u.write.count = count;
+	// old version uses bulk, new version uses control
+	m.u.write.max_packet = instance->peer_version < 2 || force_bulk ? 0 : 4000;
+#if defined(CONFIG_64BIT)
+	m.u.write.callbackl = (u32) (((unsigned long) alsa_stream->fifo_irq_handler)&0xFFFFFFFF);
+	m.u.write.callbackh = (u32) ((((unsigned long) alsa_stream->fifo_irq_handler) >> 32)&0xFFFFFFFF);
+#else
+	m.u.write.callback = alsa_stream->fifo_irq_handler;
+	m.u.write.cookie = alsa_stream;
+#endif
+	m.u.write.silence = src == NULL;
+
+	/* Send the message to the videocore */
+	status = bcm2835_vchi_msg_queue(instance->vchi_handle[0],
+					&m, sizeof(m));
+
+	if (status) {
+		LOG_ERR("%s: failed on vchi_msg_queue (status=%d)\n",
+			__func__, status);
+
+		ret = -1;
+		goto unlock;
+	}
+	if (!m.u.write.silence) {
+		if (!m.u.write.max_packet) {
+			/* Send the message to the videocore */
+			status = vchi_bulk_queue_transmit(instance->vchi_handle[0],
+				src, count,
+				0 *
+				VCHI_FLAGS_BLOCK_UNTIL_QUEUED
+				+
+				1 *
+				VCHI_FLAGS_BLOCK_UNTIL_DATA_READ,
+				NULL);
+		} else {
+			while (count > 0) {
+				int bytes = min((int) m.u.write.max_packet, (int) count);
+				status = bcm2835_vchi_msg_queue(instance->vchi_handle[0],
+								src, bytes);
+				src = (char *)src + bytes;
+				count -= bytes;
+			}
+		}
+		if (status) {
+			LOG_ERR("%s: failed on vchi_bulk_queue_transmit (status=%d)\n",
+				__func__, status);
+
+			ret = -1;
+			goto unlock;
+		}
+	}
+	ret = 0;
+
+unlock:
+	vchi_service_release(instance->vchi_handle[0]);
+	mutex_unlock(&instance->vchi_mutex);
+	LOG_DBG(" .. OUT\n");
+	return ret;
+}
+
+/**
+ * Returns all buffers from arm->vc
+ */
+void bcm2835_audio_flush_buffers(struct bcm2835_alsa_stream *alsa_stream)
+{
+	LOG_DBG(" .. IN\n");
+	LOG_DBG(" .. OUT\n");
+	return;
+}
+
+/**
+ * Forces VC to flush(drop) its filled playback buffers and
+ * return them the us. (VC->ARM)
+ */
+void bcm2835_audio_flush_playback_buffers(struct bcm2835_alsa_stream *alsa_stream)
+{
+	LOG_DBG(" .. IN\n");
+	LOG_DBG(" .. OUT\n");
+}
+
+unsigned int bcm2835_audio_retrieve_buffers(struct bcm2835_alsa_stream *alsa_stream)
+{
+	unsigned int count = atomic_read(&alsa_stream->retrieved);
+	atomic_sub(count, &alsa_stream->retrieved);
+	return count;
+}
+
+module_param(force_bulk, bool, 0444);
+MODULE_PARM_DESC(force_bulk, "Force use of vchiq bulk for audio");