Merge tag 'soundwire-4.20-rc1' of...

Merge tag 'soundwire-4.20-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/vkoul/soundwire into char-misc-next

Vinod writes:

soundwire updates for 4.20-rc1

 - support for multi-link streaming
 - updates in intel driver for multi-link streaming
 - Update Vinod's email
 - Fix rst formatting

* tag 'soundwire-4.20-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/vkoul/soundwire:
  Documentation: soundwire: fix stream.rst markup warnings
  soundwire: intel: Remove duplicate assignment
  MAINTAINERS: Update Vinod's email
  soundwire: intel: Fix uninitialized adev deref
  soundwire: intel: Add pre/post bank switch ops
  soundwire: keep track of Masters in a stream
  soundwire: Add support for multi link bank switch
  soundwire: Handle multiple master instances in a stream
  soundwire: Add support to lock across bus instances
  soundwire: Initialize completion for defer messages
  Documentation: soundwire: Add documentation for multi link

Documentation/driver-api/soundwire/stream.rst

@@ -101,6 +101,34 @@ interface. ::
 	+--------------------+                             |                |
 							   +----------------+
 
+Example 5: Stereo Stream with L and R channel is rendered by 2 Masters, each
+rendering one channel, and is received by two different Slaves, each
+receiving one channel. Both Masters and both Slaves are using single port. ::
+
+	+---------------+                    Clock Signal  +---------------+
+	|    Master     +----------------------------------+     Slave     |
+	|   Interface   |                                  |   Interface   |
+	|       1       |                                  |       1       |
+	|               |                     Data Signal  |               |
+	|       L       +----------------------------------+       L       |
+	|     (Data)    |     Data Direction               |     (Data)    |
+	+---------------+  +----------------------->       +---------------+
+
+	+---------------+                    Clock Signal  +---------------+
+	|    Master     +----------------------------------+     Slave     |
+	|   Interface   |                                  |   Interface   |
+	|       2       |                                  |       2       |
+	|               |                     Data Signal  |               |
+	|       R       +----------------------------------+       R       |
+	|     (Data)    |     Data Direction               |     (Data)    |
+	+---------------+  +----------------------->       +---------------+
+
+Note: In multi-link cases like above, to lock, one would acquire a global
+lock and then go on locking bus instances. But, in this case the caller
+framework(ASoC DPCM) guarantees that stream operations on a card are
+always serialized. So, there is no race condition and hence no need for
+global lock.
+
 SoundWire Stream Management flow
 ================================
 
@@ -174,6 +202,7 @@ per stream. From ASoC DPCM framework, this stream state maybe linked to
 .startup() operation.
 
   .. code-block:: c
+
   int sdw_alloc_stream(char * stream_name);
 
 
@@ -200,6 +229,7 @@ only be invoked once by respective Master(s) and Slave(s). From ASoC DPCM
 framework, this stream state is linked to .hw_params() operation.
 
   .. code-block:: c
+
   int sdw_stream_add_master(struct sdw_bus * bus,
 		struct sdw_stream_config * stream_config,
 		struct sdw_ports_config * ports_config,
@@ -245,6 +275,7 @@ stream. From ASoC DPCM framework, this stream state is linked to
 .prepare() operation.
 
   .. code-block:: c
+
   int sdw_prepare_stream(struct sdw_stream_runtime * stream);
 
 
@@ -274,6 +305,7 @@ stream. From ASoC DPCM framework, this stream state is linked to
 .trigger() start operation.
 
   .. code-block:: c
+
   int sdw_enable_stream(struct sdw_stream_runtime * stream);
 
 SDW_STREAM_DISABLED
@@ -301,6 +333,7 @@ per stream. From ASoC DPCM framework, this stream state is linked to
 .trigger() stop operation.
 
   .. code-block:: c
+
   int sdw_disable_stream(struct sdw_stream_runtime * stream);
 
 
@@ -325,6 +358,7 @@ per stream. From ASoC DPCM framework, this stream state is linked to
 .trigger() stop operation.
 
   .. code-block:: c
+
   int sdw_deprepare_stream(struct sdw_stream_runtime * stream);
 
 
@@ -349,6 +383,7 @@ all the Master(s) and Slave(s) associated with stream. From ASoC DPCM
 framework, this stream state is linked to .hw_free() operation.
 
   .. code-block:: c
+
   int sdw_stream_remove_master(struct sdw_bus * bus,
 		struct sdw_stream_runtime * stream);
   int sdw_stream_remove_slave(struct sdw_slave * slave,
@@ -361,6 +396,7 @@ stream assigned as part of ALLOCATED state.
 In .shutdown() the data structure maintaining stream state are freed up.
 
   .. code-block:: c
+
   void sdw_release_stream(struct sdw_stream_runtime * stream);
 
 Not Supported

MAINTAINERS

@@ -13619,7 +13619,7 @@ F:	sound/soc/
 F:	include/sound/soc*
 
 SOUNDWIRE SUBSYSTEM
-M:	Vinod Koul <vinod.koul@intel.com>
+M:	Vinod Koul <vkoul@kernel.org>
 M:	Sanyog Kale <sanyog.r.kale@intel.com>
 R:	Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
 L:	alsa-devel@alsa-project.org (moderated for non-subscribers)

drivers/soundwire/bus.c

@@ -35,6 +35,11 @@ int sdw_add_bus_master(struct sdw_bus *bus)
 	INIT_LIST_HEAD(&bus->slaves);
 	INIT_LIST_HEAD(&bus->m_rt_list);
 
+	/*
+	 * Initialize multi_link flag
+	 * TODO: populate this flag by reading property from FW node
+	 */
+	bus->multi_link = false;
 	if (bus->ops->read_prop) {
 		ret = bus->ops->read_prop(bus);
 		if (ret < 0) {
@@ -175,6 +180,7 @@ static inline int do_transfer_defer(struct sdw_bus *bus,
 
 	defer->msg = msg;
 	defer->length = msg->len;
+	init_completion(&defer->complete);
 
 	for (i = 0; i <= retry; i++) {
 		resp = bus->ops->xfer_msg_defer(bus, msg, defer);

drivers/soundwire/bus.h

@@ -4,6 +4,8 @@
 #ifndef __SDW_BUS_H
 #define __SDW_BUS_H
 
+#define DEFAULT_BANK_SWITCH_TIMEOUT 3000
+
 #if IS_ENABLED(CONFIG_ACPI)
 int sdw_acpi_find_slaves(struct sdw_bus *bus);
 #else
@@ -99,6 +101,7 @@ struct sdw_slave_runtime {
  * this stream, can be zero.
  * @slave_rt_list: Slave runtime list
  * @port_list: List of Master Ports configured for this stream, can be zero.
+ * @stream_node: sdw_stream_runtime master_list node
  * @bus_node: sdw_bus m_rt_list node
  */
 struct sdw_master_runtime {
@@ -108,6 +111,7 @@ struct sdw_master_runtime {
 	unsigned int ch_count;
 	struct list_head slave_rt_list;
 	struct list_head port_list;
+	struct list_head stream_node;
 	struct list_head bus_node;
 };
 

drivers/soundwire/intel.c

@@ -397,6 +397,69 @@ static int intel_config_stream(struct sdw_intel *sdw,
 	return -EIO;
 }
 
+/*
+ * bank switch routines
+ */
+
+static int intel_pre_bank_switch(struct sdw_bus *bus)
+{
+	struct sdw_cdns *cdns = bus_to_cdns(bus);
+	struct sdw_intel *sdw = cdns_to_intel(cdns);
+	void __iomem *shim = sdw->res->shim;
+	int sync_reg;
+
+	/* Write to register only for multi-link */
+	if (!bus->multi_link)
+		return 0;
+
+	/* Read SYNC register */
+	sync_reg = intel_readl(shim, SDW_SHIM_SYNC);
+	sync_reg |= SDW_SHIM_SYNC_CMDSYNC << sdw->instance;
+	intel_writel(shim, SDW_SHIM_SYNC, sync_reg);
+
+	return 0;
+}
+
+static int intel_post_bank_switch(struct sdw_bus *bus)
+{
+	struct sdw_cdns *cdns = bus_to_cdns(bus);
+	struct sdw_intel *sdw = cdns_to_intel(cdns);
+	void __iomem *shim = sdw->res->shim;
+	int sync_reg, ret;
+
+	/* Write to register only for multi-link */
+	if (!bus->multi_link)
+		return 0;
+
+	/* Read SYNC register */
+	sync_reg = intel_readl(shim, SDW_SHIM_SYNC);
+
+	/*
+	 * post_bank_switch() ops is called from the bus in loop for
+	 * all the Masters in the steam with the expectation that
+	 * we trigger the bankswitch for the only first Master in the list
+	 * and do nothing for the other Masters
+	 *
+	 * So, set the SYNCGO bit only if CMDSYNC bit is set for any Master.
+	 */
+	if (!(sync_reg & SDW_SHIM_SYNC_CMDSYNC_MASK))
+		return 0;
+
+	/*
+	 * Set SyncGO bit to synchronously trigger a bank switch for
+	 * all the masters. A write to SYNCGO bit clears CMDSYNC bit for all
+	 * the Masters.
+	 */
+	sync_reg |= SDW_SHIM_SYNC_SYNCGO;
+
+	ret = intel_clear_bit(shim, SDW_SHIM_SYNC, sync_reg,
+					SDW_SHIM_SYNC_SYNCGO);
+	if (ret < 0)
+		dev_err(sdw->cdns.dev, "Post bank switch failed: %d", ret);
+
+	return ret;
+}
+
 /*
  * DAI routines
  */
@@ -750,6 +813,8 @@ static struct sdw_master_ops sdw_intel_ops = {
 	.xfer_msg_defer = cdns_xfer_msg_defer,
 	.reset_page_addr = cdns_reset_page_addr,
 	.set_bus_conf = cdns_bus_conf,
+	.pre_bank_switch = intel_pre_bank_switch,
+	.post_bank_switch = intel_post_bank_switch,
 };
 
 /*
@@ -780,9 +845,6 @@ static int intel_probe(struct platform_device *pdev)
 	sdw_intel_ops.read_prop = intel_prop_read;
 	sdw->cdns.bus.ops = &sdw_intel_ops;
 
-	sdw_intel_ops.read_prop = intel_prop_read;
-	sdw->cdns.bus.ops = &sdw_intel_ops;
-
 	platform_set_drvdata(pdev, sdw);
 
 	ret = sdw_add_bus_master(&sdw->cdns.bus);

drivers/soundwire/intel_init.c

@@ -151,7 +151,7 @@ static acpi_status sdw_intel_acpi_cb(acpi_handle handle, u32 level,
 	struct acpi_device *adev;
 
 	if (acpi_bus_get_device(handle, &adev)) {
-		dev_err(&adev->dev, "Couldn't find ACPI handle\n");
+		pr_err("%s: Couldn't find ACPI handle\n", __func__);
 		return AE_NOT_FOUND;
 	}
 

drivers/soundwire/stream.c

@@ -626,9 +626,10 @@ static int sdw_program_params(struct sdw_bus *bus)
 	return ret;
 }
 
-static int sdw_bank_switch(struct sdw_bus *bus)
+static int sdw_bank_switch(struct sdw_bus *bus, int m_rt_count)
 {
 	int col_index, row_index;
+	bool multi_link;
 	struct sdw_msg *wr_msg;
 	u8 *wbuf = NULL;
 	int ret = 0;
@@ -638,6 +639,8 @@ static int sdw_bank_switch(struct sdw_bus *bus)
 	if (!wr_msg)
 		return -ENOMEM;
 
+	bus->defer_msg.msg = wr_msg;
+
 	wbuf = kzalloc(sizeof(*wbuf), GFP_KERNEL);
 	if (!wbuf) {
 		ret = -ENOMEM;
@@ -658,17 +661,29 @@ static int sdw_bank_switch(struct sdw_bus *bus)
 					SDW_MSG_FLAG_WRITE, wbuf);
 	wr_msg->ssp_sync = true;
 
-	ret = sdw_transfer(bus, wr_msg);
+	/*
+	 * Set the multi_link flag only when both the hardware supports
+	 * and there is a stream handled by multiple masters
+	 */
+	multi_link = bus->multi_link && (m_rt_count > 1);
+
+	if (multi_link)
+		ret = sdw_transfer_defer(bus, wr_msg, &bus->defer_msg);
+	else
+		ret = sdw_transfer(bus, wr_msg);
+
 	if (ret < 0) {
 		dev_err(bus->dev, "Slave frame_ctrl reg write failed");
 		goto error;
 	}
 
-	kfree(wr_msg);
-	kfree(wbuf);
-	bus->defer_msg.msg = NULL;
-	bus->params.curr_bank = !bus->params.curr_bank;
-	bus->params.next_bank = !bus->params.next_bank;
+	if (!multi_link) {
+		kfree(wr_msg);
+		kfree(wbuf);
+		bus->defer_msg.msg = NULL;
+		bus->params.curr_bank = !bus->params.curr_bank;
+		bus->params.next_bank = !bus->params.next_bank;
+	}
 
 	return 0;
 
@@ -679,37 +694,138 @@ static int sdw_bank_switch(struct sdw_bus *bus)
 	return ret;
 }
 
+/**
+ * sdw_ml_sync_bank_switch: Multilink register bank switch
+ *
+ * @bus: SDW bus instance
+ *
+ * Caller function should free the buffers on error
+ */
+static int sdw_ml_sync_bank_switch(struct sdw_bus *bus)
+{
+	unsigned long time_left;
+
+	if (!bus->multi_link)
+		return 0;
+
+	/* Wait for completion of transfer */
+	time_left = wait_for_completion_timeout(&bus->defer_msg.complete,
+						bus->bank_switch_timeout);
+
+	if (!time_left) {
+		dev_err(bus->dev, "Controller Timed out on bank switch");
+		return -ETIMEDOUT;
+	}
+
+	bus->params.curr_bank = !bus->params.curr_bank;
+	bus->params.next_bank = !bus->params.next_bank;
+
+	if (bus->defer_msg.msg) {
+		kfree(bus->defer_msg.msg->buf);
+		kfree(bus->defer_msg.msg);
+	}
+
+	return 0;
+}
+
 static int do_bank_switch(struct sdw_stream_runtime *stream)
 {
-	struct sdw_master_runtime *m_rt = stream->m_rt;
+	struct sdw_master_runtime *m_rt = NULL;
 	const struct sdw_master_ops *ops;
-	struct sdw_bus *bus = m_rt->bus;
+	struct sdw_bus *bus = NULL;
+	bool multi_link = false;
 	int ret = 0;
 
-	ops = bus->ops;
+	list_for_each_entry(m_rt, &stream->master_list, stream_node) {
+		bus = m_rt->bus;
+		ops = bus->ops;
+
+		if (bus->multi_link) {
+			multi_link = true;
+			mutex_lock(&bus->msg_lock);
+		}
+
+		/* Pre-bank switch */
+		if (ops->pre_bank_switch) {
+			ret = ops->pre_bank_switch(bus);
+			if (ret < 0) {
+				dev_err(bus->dev,
+					"Pre bank switch op failed: %d", ret);
+				goto msg_unlock;
+			}
+		}
 
-	/* Pre-bank switch */
-	if (ops->pre_bank_switch) {
-		ret = ops->pre_bank_switch(bus);
+		/*
+		 * Perform Bank switch operation.
+		 * For multi link cases, the actual bank switch is
+		 * synchronized across all Masters and happens later as a
+		 * part of post_bank_switch ops.
+		 */
+		ret = sdw_bank_switch(bus, stream->m_rt_count);
 		if (ret < 0) {
-			dev_err(bus->dev, "Pre bank switch op failed: %d", ret);
-			return ret;
+			dev_err(bus->dev, "Bank switch failed: %d", ret);
+			goto error;
+
 		}
 	}
 
-	/* Bank switch */
-	ret = sdw_bank_switch(bus);
-	if (ret < 0) {
-		dev_err(bus->dev, "Bank switch failed: %d", ret);
-		return ret;
-	}
+	/*
+	 * For multi link cases, it is expected that the bank switch is
+	 * triggered by the post_bank_switch for the first Master in the list
+	 * and for the other Masters the post_bank_switch() should return doing
+	 * nothing.
+	 */
+	list_for_each_entry(m_rt, &stream->master_list, stream_node) {
+		bus = m_rt->bus;
+		ops = bus->ops;
+
+		/* Post-bank switch */
+		if (ops->post_bank_switch) {
+			ret = ops->post_bank_switch(bus);
+			if (ret < 0) {
+				dev_err(bus->dev,
+					"Post bank switch op failed: %d", ret);
+				goto error;
+			}
+		} else if (bus->multi_link && stream->m_rt_count > 1) {
+			dev_err(bus->dev,
+				"Post bank switch ops not implemented");
+			goto error;
+		}
+
+		/* Set the bank switch timeout to default, if not set */
+		if (!bus->bank_switch_timeout)
+			bus->bank_switch_timeout = DEFAULT_BANK_SWITCH_TIMEOUT;
 
-	/* Post-bank switch */
-	if (ops->post_bank_switch) {
-		ret = ops->post_bank_switch(bus);
+		/* Check if bank switch was successful */
+		ret = sdw_ml_sync_bank_switch(bus);
 		if (ret < 0) {
 			dev_err(bus->dev,
-					"Post bank switch op failed: %d", ret);
+				"multi link bank switch failed: %d", ret);
+			goto error;
+		}
+
+		mutex_unlock(&bus->msg_lock);
+	}
+
+	return ret;
+
+error:
+	list_for_each_entry(m_rt, &stream->master_list, stream_node) {
+
+		bus = m_rt->bus;
+
+		kfree(bus->defer_msg.msg->buf);
+		kfree(bus->defer_msg.msg);
+	}
+
+msg_unlock:
+
+	if (multi_link) {
+		list_for_each_entry(m_rt, &stream->master_list, stream_node) {
+			bus = m_rt->bus;
+			if (mutex_is_locked(&bus->msg_lock))
+				mutex_unlock(&bus->msg_lock);
 		}
 	}
 
@@ -747,12 +863,29 @@ struct sdw_stream_runtime *sdw_alloc_stream(char *stream_name)
 		return NULL;
 
 	stream->name = stream_name;
+	INIT_LIST_HEAD(&stream->master_list);
 	stream->state = SDW_STREAM_ALLOCATED;
+	stream->m_rt_count = 0;
 
 	return stream;
 }
 EXPORT_SYMBOL(sdw_alloc_stream);
 
+static struct sdw_master_runtime
+*sdw_find_master_rt(struct sdw_bus *bus,
+			struct sdw_stream_runtime *stream)
+{
+	struct sdw_master_runtime *m_rt = NULL;
+
+	/* Retrieve Bus handle if already available */
+	list_for_each_entry(m_rt, &stream->master_list, stream_node) {
+		if (m_rt->bus == bus)
+			return m_rt;
+	}
+
+	return NULL;
+}
+
 /**
  * sdw_alloc_master_rt() - Allocates and initialize Master runtime handle
  *
@@ -769,12 +902,11 @@ static struct sdw_master_runtime
 {
 	struct sdw_master_runtime *m_rt;
 
-	m_rt = stream->m_rt;
-
 	/*
 	 * check if Master is already allocated (as a result of Slave adding
 	 * it first), if so skip allocation and go to configure
 	 */
+	m_rt = sdw_find_master_rt(bus, stream);
 	if (m_rt)
 		goto stream_config;
 
@@ -785,7 +917,7 @@ static struct sdw_master_runtime
 	/* Initialization of Master runtime handle */
 	INIT_LIST_HEAD(&m_rt->port_list);
 	INIT_LIST_HEAD(&m_rt->slave_rt_list);
-	stream->m_rt = m_rt;
+	list_add_tail(&m_rt->stream_node, &stream->master_list);
 
 	list_add_tail(&m_rt->bus_node, &bus->m_rt_list);
 
@@ -843,17 +975,21 @@ static void sdw_slave_port_release(struct sdw_bus *bus,
 			struct sdw_stream_runtime *stream)
 {
 	struct sdw_port_runtime *p_rt, *_p_rt;
-	struct sdw_master_runtime *m_rt = stream->m_rt;
+	struct sdw_master_runtime *m_rt;
 	struct sdw_slave_runtime *s_rt;
 
-	list_for_each_entry(s_rt, &m_rt->slave_rt_list, m_rt_node) {
-		if (s_rt->slave != slave)
-			continue;
+	list_for_each_entry(m_rt, &stream->master_list, stream_node) {
+		list_for_each_entry(s_rt, &m_rt->slave_rt_list, m_rt_node) {
 
-		list_for_each_entry_safe(p_rt, _p_rt,
-				&s_rt->port_list, port_node) {
-			list_del(&p_rt->port_node);
-			kfree(p_rt);
+			if (s_rt->slave != slave)
+				continue;
+
+			list_for_each_entry_safe(p_rt, _p_rt,
+					&s_rt->port_list, port_node) {
+
+				list_del(&p_rt->port_node);
+				kfree(p_rt);
+			}
 		}
 	}
 }
@@ -870,16 +1006,18 @@ static void sdw_release_slave_stream(struct sdw_slave *slave,
 			struct sdw_stream_runtime *stream)
 {
 	struct sdw_slave_runtime *s_rt, *_s_rt;
-	struct sdw_master_runtime *m_rt = stream->m_rt;
+	struct sdw_master_runtime *m_rt;
 
-	/* Retrieve Slave runtime handle */
-	list_for_each_entry_safe(s_rt, _s_rt,
-			&m_rt->slave_rt_list, m_rt_node) {
+	list_for_each_entry(m_rt, &stream->master_list, stream_node) {
+		/* Retrieve Slave runtime handle */
+		list_for_each_entry_safe(s_rt, _s_rt,
+					&m_rt->slave_rt_list, m_rt_node) {
 
-		if (s_rt->slave == slave) {
-			list_del(&s_rt->m_rt_node);
-			kfree(s_rt);
-			return;
+			if (s_rt->slave == slave) {
+				list_del(&s_rt->m_rt_node);
+				kfree(s_rt);
+				return;
+			}
 		}
 	}
 }
@@ -887,6 +1025,7 @@ static void sdw_release_slave_stream(struct sdw_slave *slave,
 /**
  * sdw_release_master_stream() - Free Master runtime handle
  *
+ * @m_rt: Master runtime node
  * @stream: Stream runtime handle.
  *
  * This function is to be called with bus_lock held
@@ -894,9 +1033,9 @@ static void sdw_release_slave_stream(struct sdw_slave *slave,
  * handle. If this is called first then sdw_release_slave_stream() will have
  * no effect as Slave(s) runtime handle would already be freed up.
  */
-static void sdw_release_master_stream(struct sdw_stream_runtime *stream)
+static void sdw_release_master_stream(struct sdw_master_runtime *m_rt,
+			struct sdw_stream_runtime *stream)
 {
-	struct sdw_master_runtime *m_rt = stream->m_rt;
 	struct sdw_slave_runtime *s_rt, *_s_rt;
 
 	list_for_each_entry_safe(s_rt, _s_rt, &m_rt->slave_rt_list, m_rt_node) {
@@ -904,7 +1043,9 @@ static void sdw_release_master_stream(struct sdw_stream_runtime *stream)
 		sdw_release_slave_stream(s_rt->slave, stream);
 	}
 
+	list_del(&m_rt->stream_node);
 	list_del(&m_rt->bus_node);
+	kfree(m_rt);
 }
 
 /**
@@ -918,13 +1059,23 @@ static void sdw_release_master_stream(struct sdw_stream_runtime *stream)
 int sdw_stream_remove_master(struct sdw_bus *bus,
 		struct sdw_stream_runtime *stream)
 {
+	struct sdw_master_runtime *m_rt, *_m_rt;
+
 	mutex_lock(&bus->bus_lock);
 
-	sdw_release_master_stream(stream);
-	sdw_master_port_release(bus, stream->m_rt);
-	stream->state = SDW_STREAM_RELEASED;
-	kfree(stream->m_rt);
-	stream->m_rt = NULL;
+	list_for_each_entry_safe(m_rt, _m_rt,
+			&stream->master_list, stream_node) {
+
+		if (m_rt->bus != bus)
+			continue;
+
+		sdw_master_port_release(bus, m_rt);
+		sdw_release_master_stream(m_rt, stream);
+		stream->m_rt_count--;
+	}
+
+	if (list_empty(&stream->master_list))
+		stream->state = SDW_STREAM_RELEASED;
 
 	mutex_unlock(&bus->bus_lock);
 
@@ -1107,6 +1258,18 @@ int sdw_stream_add_master(struct sdw_bus *bus,
 
 	mutex_lock(&bus->bus_lock);
 
+	/*
+	 * For multi link streams, add the second master only if
+	 * the bus supports it.
+	 * Check if bus->multi_link is set
+	 */
+	if (!bus->multi_link && stream->m_rt_count > 0) {
+		dev_err(bus->dev,
+			"Multilink not supported, link %d", bus->link_id);
+		ret = -EINVAL;
+		goto unlock;
+	}
+
 	m_rt = sdw_alloc_master_rt(bus, stream_config, stream);
 	if (!m_rt) {
 		dev_err(bus->dev,
@@ -1124,10 +1287,12 @@ int sdw_stream_add_master(struct sdw_bus *bus,
 	if (ret)
 		goto stream_error;
 
+	stream->m_rt_count++;
+
 	goto unlock;
 
 stream_error:
-	sdw_release_master_stream(stream);
+	sdw_release_master_stream(m_rt, stream);
 unlock:
 	mutex_unlock(&bus->bus_lock);
 	return ret;
@@ -1205,7 +1370,7 @@ int sdw_stream_add_slave(struct sdw_slave *slave,
 	 * we hit error so cleanup the stream, release all Slave(s) and
 	 * Master runtime
 	 */
-	sdw_release_master_stream(stream);
+	sdw_release_master_stream(m_rt, stream);
 error:
 	mutex_unlock(&slave->bus->bus_lock);
 	return ret;
@@ -1245,33 +1410,82 @@ struct sdw_dpn_prop *sdw_get_slave_dpn_prop(struct sdw_slave *slave,
 	return NULL;
 }
 
+/**
+ * sdw_acquire_bus_lock: Acquire bus lock for all Master runtime(s)
+ *
+ * @stream: SoundWire stream
+ *
+ * Acquire bus_lock for each of the master runtime(m_rt) part of this
+ * stream to reconfigure the bus.
+ * NOTE: This function is called from SoundWire stream ops and is
+ * expected that a global lock is held before acquiring bus_lock.
+ */
+static void sdw_acquire_bus_lock(struct sdw_stream_runtime *stream)
+{
+	struct sdw_master_runtime *m_rt = NULL;
+	struct sdw_bus *bus = NULL;
+
+	/* Iterate for all Master(s) in Master list */
+	list_for_each_entry(m_rt, &stream->master_list, stream_node) {
+		bus = m_rt->bus;
+
+		mutex_lock(&bus->bus_lock);
+	}
+}
+
+/**
+ * sdw_release_bus_lock: Release bus lock for all Master runtime(s)
+ *
+ * @stream: SoundWire stream
+ *
+ * Release the previously held bus_lock after reconfiguring the bus.
+ * NOTE: This function is called from SoundWire stream ops and is
+ * expected that a global lock is held before releasing bus_lock.
+ */
+static void sdw_release_bus_lock(struct sdw_stream_runtime *stream)
+{
+	struct sdw_master_runtime *m_rt = NULL;
+	struct sdw_bus *bus = NULL;
+
+	/* Iterate for all Master(s) in Master list */
+	list_for_each_entry_reverse(m_rt, &stream->master_list, stream_node) {
+		bus = m_rt->bus;
+		mutex_unlock(&bus->bus_lock);
+	}
+}
+
 static int _sdw_prepare_stream(struct sdw_stream_runtime *stream)
 {
-	struct sdw_master_runtime *m_rt = stream->m_rt;
-	struct sdw_bus *bus = m_rt->bus;
+	struct sdw_master_runtime *m_rt = NULL;
+	struct sdw_bus *bus = NULL;
 	struct sdw_master_prop *prop = NULL;
 	struct sdw_bus_params params;
 	int ret;
 
-	prop = &bus->prop;
-	memcpy(&params, &bus->params, sizeof(params));
+	/* Prepare  Master(s) and Slave(s) port(s) associated with stream */
+	list_for_each_entry(m_rt, &stream->master_list, stream_node) {
+		bus = m_rt->bus;
+		prop = &bus->prop;
+		memcpy(&params, &bus->params, sizeof(params));
 
-	/* TODO: Support Asynchronous mode */
-	if ((prop->max_freq % stream->params.rate) != 0) {
-		dev_err(bus->dev, "Async mode not supported");
-		return -EINVAL;
-	}
+		/* TODO: Support Asynchronous mode */
+		if ((prop->max_freq % stream->params.rate) != 0) {
+			dev_err(bus->dev, "Async mode not supported");
+			return -EINVAL;
+		}
 
-	/* Increment cumulative bus bandwidth */
-	/* TODO: Update this during Device-Device support */
-	bus->params.bandwidth += m_rt->stream->params.rate *
-		m_rt->ch_count * m_rt->stream->params.bps;
+		/* Increment cumulative bus bandwidth */
+		/* TODO: Update this during Device-Device support */
+		bus->params.bandwidth += m_rt->stream->params.rate *
+			m_rt->ch_count * m_rt->stream->params.bps;
+
+		/* Program params */
+		ret = sdw_program_params(bus);
+		if (ret < 0) {
+			dev_err(bus->dev, "Program params failed: %d", ret);
+			goto restore_params;
+		}
 
-	/* Program params */
-	ret = sdw_program_params(bus);
-	if (ret < 0) {
-		dev_err(bus->dev, "Program params failed: %d", ret);
-		goto restore_params;
 	}
 
 	ret = do_bank_switch(stream);
@@ -1280,12 +1494,16 @@ static int _sdw_prepare_stream(struct sdw_stream_runtime *stream)
 		goto restore_params;
 	}
 
-	/* Prepare port(s) on the new clock configuration */
-	ret = sdw_prep_deprep_ports(m_rt, true);
-	if (ret < 0) {
-		dev_err(bus->dev, "Prepare port(s) failed ret = %d",
-				ret);
-		return ret;
+	list_for_each_entry(m_rt, &stream->master_list, stream_node) {
+		bus = m_rt->bus;
+
+		/* Prepare port(s) on the new clock configuration */
+		ret = sdw_prep_deprep_ports(m_rt, true);
+		if (ret < 0) {
+			dev_err(bus->dev, "Prepare port(s) failed ret = %d",
+					ret);
+			return ret;
+		}
 	}
 
 	stream->state = SDW_STREAM_PREPARED;
@@ -1313,35 +1531,40 @@ int sdw_prepare_stream(struct sdw_stream_runtime *stream)
 		return -EINVAL;
 	}
 
-	mutex_lock(&stream->m_rt->bus->bus_lock);
+	sdw_acquire_bus_lock(stream);
 
 	ret = _sdw_prepare_stream(stream);
 	if (ret < 0)
 		pr_err("Prepare for stream:%s failed: %d", stream->name, ret);
 
-	mutex_unlock(&stream->m_rt->bus->bus_lock);
+	sdw_release_bus_lock(stream);
 	return ret;
 }
 EXPORT_SYMBOL(sdw_prepare_stream);
 
 static int _sdw_enable_stream(struct sdw_stream_runtime *stream)
 {
-	struct sdw_master_runtime *m_rt = stream->m_rt;
-	struct sdw_bus *bus = m_rt->bus;
+	struct sdw_master_runtime *m_rt = NULL;
+	struct sdw_bus *bus = NULL;
 	int ret;
 
-	/* Program params */
-	ret = sdw_program_params(bus);
-	if (ret < 0) {
-		dev_err(bus->dev, "Program params failed: %d", ret);
-		return ret;
-	}
+	/* Enable Master(s) and Slave(s) port(s) associated with stream */
+	list_for_each_entry(m_rt, &stream->master_list, stream_node) {
+		bus = m_rt->bus;
 
-	/* Enable port(s) */
-	ret = sdw_enable_disable_ports(m_rt, true);
-	if (ret < 0) {
-		dev_err(bus->dev, "Enable port(s) failed ret: %d", ret);
-		return ret;
+		/* Program params */
+		ret = sdw_program_params(bus);
+		if (ret < 0) {
+			dev_err(bus->dev, "Program params failed: %d", ret);
+			return ret;
+		}
+
+		/* Enable port(s) */
+		ret = sdw_enable_disable_ports(m_rt, true);
+		if (ret < 0) {
+			dev_err(bus->dev, "Enable port(s) failed ret: %d", ret);
+			return ret;
+		}
 	}
 
 	ret = do_bank_switch(stream);
@@ -1370,37 +1593,42 @@ int sdw_enable_stream(struct sdw_stream_runtime *stream)
 		return -EINVAL;
 	}
 
-	mutex_lock(&stream->m_rt->bus->bus_lock);
+	sdw_acquire_bus_lock(stream);
 
 	ret = _sdw_enable_stream(stream);
 	if (ret < 0)
 		pr_err("Enable for stream:%s failed: %d", stream->name, ret);
 
-	mutex_unlock(&stream->m_rt->bus->bus_lock);
+	sdw_release_bus_lock(stream);
 	return ret;
 }
 EXPORT_SYMBOL(sdw_enable_stream);
 
 static int _sdw_disable_stream(struct sdw_stream_runtime *stream)
 {
-	struct sdw_master_runtime *m_rt = stream->m_rt;
-	struct sdw_bus *bus = m_rt->bus;
+	struct sdw_master_runtime *m_rt = NULL;
+	struct sdw_bus *bus = NULL;
 	int ret;
 
-	/* Disable port(s) */
-	ret = sdw_enable_disable_ports(m_rt, false);
-	if (ret < 0) {
-		dev_err(bus->dev, "Disable port(s) failed: %d", ret);
-		return ret;
+	list_for_each_entry(m_rt, &stream->master_list, stream_node) {
+		bus = m_rt->bus;
+		/* Disable port(s) */
+		ret = sdw_enable_disable_ports(m_rt, false);
+		if (ret < 0) {
+			dev_err(bus->dev, "Disable port(s) failed: %d", ret);
+			return ret;
+		}
 	}
-
 	stream->state = SDW_STREAM_DISABLED;
 
-	/* Program params */
-	ret = sdw_program_params(bus);
-	if (ret < 0) {
-		dev_err(bus->dev, "Program params failed: %d", ret);
-		return ret;
+	list_for_each_entry(m_rt, &stream->master_list, stream_node) {
+		bus = m_rt->bus;
+		/* Program params */
+		ret = sdw_program_params(bus);
+		if (ret < 0) {
+			dev_err(bus->dev, "Program params failed: %d", ret);
+			return ret;
+		}
 	}
 
 	return do_bank_switch(stream);
@@ -1422,43 +1650,46 @@ int sdw_disable_stream(struct sdw_stream_runtime *stream)
 		return -EINVAL;
 	}
 
-	mutex_lock(&stream->m_rt->bus->bus_lock);
+	sdw_acquire_bus_lock(stream);
 
 	ret = _sdw_disable_stream(stream);
 	if (ret < 0)
 		pr_err("Disable for stream:%s failed: %d", stream->name, ret);
 
-	mutex_unlock(&stream->m_rt->bus->bus_lock);
+	sdw_release_bus_lock(stream);
 	return ret;
 }
 EXPORT_SYMBOL(sdw_disable_stream);
 
 static int _sdw_deprepare_stream(struct sdw_stream_runtime *stream)
 {
-	struct sdw_master_runtime *m_rt = stream->m_rt;
-	struct sdw_bus *bus = m_rt->bus;
+	struct sdw_master_runtime *m_rt = NULL;
+	struct sdw_bus *bus = NULL;
 	int ret = 0;
 
-	/* De-prepare port(s) */
-	ret = sdw_prep_deprep_ports(m_rt, false);
-	if (ret < 0) {
-		dev_err(bus->dev, "De-prepare port(s) failed: %d", ret);
-		return ret;
-	}
+	list_for_each_entry(m_rt, &stream->master_list, stream_node) {
+		bus = m_rt->bus;
+		/* De-prepare port(s) */
+		ret = sdw_prep_deprep_ports(m_rt, false);
+		if (ret < 0) {
+			dev_err(bus->dev, "De-prepare port(s) failed: %d", ret);
+			return ret;
+		}
 
-	stream->state = SDW_STREAM_DEPREPARED;
+		/* TODO: Update this during Device-Device support */
+		bus->params.bandwidth -= m_rt->stream->params.rate *
+			m_rt->ch_count * m_rt->stream->params.bps;
 
-	/* TODO: Update this during Device-Device support */
-	bus->params.bandwidth -= m_rt->stream->params.rate *
-		m_rt->ch_count * m_rt->stream->params.bps;
+		/* Program params */
+		ret = sdw_program_params(bus);
+		if (ret < 0) {
+			dev_err(bus->dev, "Program params failed: %d", ret);
+			return ret;
+		}
 
-	/* Program params */
-	ret = sdw_program_params(bus);
-	if (ret < 0) {
-		dev_err(bus->dev, "Program params failed: %d", ret);
-		return ret;
 	}
 
+	stream->state = SDW_STREAM_DEPREPARED;
 	return do_bank_switch(stream);
 }
 
@@ -1478,13 +1709,12 @@ int sdw_deprepare_stream(struct sdw_stream_runtime *stream)
 		return -EINVAL;
 	}
 
-	mutex_lock(&stream->m_rt->bus->bus_lock);
-
+	sdw_acquire_bus_lock(stream);
 	ret = _sdw_deprepare_stream(stream);
 	if (ret < 0)
 		pr_err("De-prepare for stream:%d failed: %d", ret, ret);
 
-	mutex_unlock(&stream->m_rt->bus->bus_lock);
+	sdw_release_bus_lock(stream);
 	return ret;
 }
 EXPORT_SYMBOL(sdw_deprepare_stream);

include/linux/soundwire/sdw.h

@@ -678,6 +678,9 @@ struct sdw_master_ops {
  * @defer_msg: Defer message
  * @clk_stop_timeout: Clock stop timeout computed
  * @bank_switch_timeout: Bank switch timeout computed
+ * @multi_link: Store bus property that indicates if multi links
+ * are supported. This flag is populated by drivers after reading
+ * appropriate firmware (ACPI/DT).
  */
 struct sdw_bus {
 	struct device *dev;
@@ -694,6 +697,7 @@ struct sdw_bus {
 	struct sdw_defer defer_msg;
 	unsigned int clk_stop_timeout;
 	u32 bank_switch_timeout;
+	bool multi_link;
 };
 
 int sdw_add_bus_master(struct sdw_bus *bus);
@@ -768,14 +772,18 @@ struct sdw_stream_params {
  * @params: Stream parameters
  * @state: Current state of the stream
  * @type: Stream type PCM or PDM
- * @m_rt: Master runtime
+ * @master_list: List of Master runtime(s) in this stream.
+ * master_list can contain only one m_rt per Master instance
+ * for a stream
+ * @m_rt_count: Count of Master runtime(s) in this stream
  */
 struct sdw_stream_runtime {
 	char *name;
 	struct sdw_stream_params params;
 	enum sdw_stream_state state;
 	enum sdw_stream_type type;
-	struct sdw_master_runtime *m_rt;
+	struct list_head master_list;
+	int m_rt_count;
 };
 
 struct sdw_stream_runtime *sdw_alloc_stream(char *stream_name);