[PATCH v1 0/3] Introduce on-chip interconnect API

[PATCH v1 0/3] Introduce on-chip interconnect API

[Georgi Djakov]

Modern SoCs have multiple processors and various dedicated cores (video, gpu,
graphics, modem). These cores are talking to each other and can generate a lot
of data flowing through the on-chip interconnects. These interconnect buses
could form different topologies such as crossbar, point to point buses,
hierarchical buses or use the network-on-chip concept.

These buses have been sized usually to handle use cases with high data
throughput but it is not necessary all the time and consume a lot of power.
Furthermore, the priority between masters can vary depending on the running
use case like video playback or cpu intensive tasks.

Having an API to control the requirement of the system in term of bandwidth
and QoS, so we can adapt the interconnect configuration to match those by
scaling the frequencies, setting link priority and tuning QoS parameters.
This configuration can be a static, one-time operation done at boot for some
platforms or a dynamic set of operations that happen at run-time.

This patchset introduce a new API to get the requirement and configure the
interconnect buses across the entire chipset to fit with the current demand.
The API is NOT for changing the performance of the endpoint devices, but only
the interconnect path in between them.

The API is using a consumer/provider-based model, where the providers are
the interconnect controllers and the consumers could be various drivers.
The consumers request interconnect resources (path) to an endpoint and set
the desired constraints on this data flow path. The provider(s) receive
requests from consumers and aggregate these requests for all master-slave
pairs on that path. Then the providers configure each participating in the
topology node according to the requested data flow path, physical links and
constraints. The topology could be complicated and multi-tiered and is SoC
specific.

Below is a simplified diagram of a real-world SoC topology. The interconnect
providers are the memory front-end and the NoCs.

+----------------+    +----------------+
| HW Accelerator |--->|      M NoC     |<---------------+
+----------------+    +----------------+                |
                        |      |                    +------------+
          +-------------+      V       +------+     |            |
          |                +--------+  | PCIe |     |            |
          |                | Slaves |  +------+     |            |
          |                +--------+     |         |   C NoC    |
          V                               V         |            |
+------------------+   +------------------------+   |            |   +-----+
|                  |-->|                        |-->|            |-->| CPU |
|                  |-->|                        |<--|            |   +-----+
|      Memory      |   |         S NoC          |   +------------+
|                  |<--|                        |---------+    |
|                  |<--|                        |<------+ |    |   +--------+
+------------------+   +------------------------+       | |    +-->| Slaves |
   ^     ^    ^           ^                             | |        +--------+
   |     |    |           |                             | V
+-----+  |  +-----+    +-----+  +---------+   +----------------+   +--------+
| CPU |  |  | GPU |    | DSP |  | Masters |-->|       P NoC    |-->| Slaves |
+-----+  |  +-----+    +-----+  +---------+   +----------------+   +--------+
         |
     +-------+
     | Modem |
     +-------+

This RFC does not implement all features but only main skeleton to check the
validity of the proposal.

TODO:
 * Constraints are currently stored in internal data structure. Should PM QoS
 be used instead?
 * Extend interconect_set() to handle parameters such as latency and other QoS
   values.
 * Cache the path between the nodes instead of walking the graph on each get().
 * Sync interconnect requests with the idle state of the device.

Summary of the patches:
Patch 1 introduces the interconnect API.
Patch 2 creates the first vendor specific interconnect controller driver.
Patch 3 is a proposal for DT bindings

Changes since RFC v2 (https://lkml.org/lkml/2017/6/12/316)
* Converted documentation to rst format.
* Fixed an incorrect call to mutex_lock. Renamed max_bw to peak_bw.

Changes since RFC v1 (https://lkml.org/lkml/2017/5/15/605)
* Refactored code into shorter functions.
* Added a new aggregate() API function.
* Rearranged some structs to reduce padding bytes.

Changes since RFC v0 (https://lkml.org/lkml/2017/3/1/599)
* Removed DT support and added optional Patch 3 with new bindings proposal.
* Converted the topology into internal driver data.
* Made the framework modular.
* interconnect_get() now takes (src and dst ports as arguments).
* Removed public declarations of some structs.
* Now passing prev/next nodes to the vendor driver.
* Properly remove requests on _put().
* Added refcounting.
* Updated documentation.
* Changed struct interconnect_path to use array instead of linked list.


Georgi Djakov (3):
  interconnect: Add generic interconnect controller API
  interconnect: Add Qualcomm msm8916 interconnect provider driver
  dt-bindings: Interconnect device-tree bindings draft

 .../bindings/interconnect/interconnect.txt         |  75 ++++
 Documentation/interconnect/interconnect.rst        |  71 ++++
 drivers/Kconfig                                    |   2 +
 drivers/Makefile                                   |   1 +
 drivers/interconnect/Kconfig                       |  15 +
 drivers/interconnect/Makefile                      |   2 +
 drivers/interconnect/interconnect.c                | 376 ++++++++++++++++++
 drivers/interconnect/qcom/Kconfig                  |  12 +
 drivers/interconnect/qcom/Makefile                 |   2 +
 drivers/interconnect/qcom/interconnect_msm8916.c   | 421 +++++++++++++++++++++
 include/dt-bindings/interconnect/qcom,msm8916.h    |  87 +++++
 include/linux/interconnect-consumer.h              |  72 ++++
 include/linux/interconnect-provider.h              | 120 ++++++
 13 files changed, 1256 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/interconnect/interconnect.txt
 create mode 100644 Documentation/interconnect/interconnect.rst
 create mode 100644 drivers/interconnect/Kconfig
 create mode 100644 drivers/interconnect/Makefile
 create mode 100644 drivers/interconnect/interconnect.c
 create mode 100644 drivers/interconnect/qcom/Kconfig
 create mode 100644 drivers/interconnect/qcom/Makefile
 create mode 100644 drivers/interconnect/qcom/interconnect_msm8916.c
 create mode 100644 include/dt-bindings/interconnect/qcom,msm8916.h
 create mode 100644 include/linux/interconnect-consumer.h
 create mode 100644 include/linux/interconnect-provider.h

[PATCH v1 1/3] interconnect: Add generic interconnect controller API

[Georgi Djakov]

This patch introduce a new API to get the requirement and configure the
interconnect buses across the entire chipset to fit with the current demand.

The API is using a consumer/provider-based model, where the providers are
the interconnect controllers and the consumers could be various drivers.
The consumers request interconnect resources (path) to an endpoint and set
the desired constraints on this data flow path. The provider(s) receive
requests from consumers and aggregate these requests for all master-slave
pairs on that path. Then the providers configure each participating in the
topology node according to the requested data flow path, physical links and
constraints. The topology could be complicated and multi-tiered and is SoC
specific.

Signed-off-by: Georgi Djakov <georgi.djakov@linaro.org>
---
 Documentation/interconnect/interconnect.rst |  71 ++++++
 drivers/Kconfig                             |   2 +
 drivers/Makefile                            |   1 +
 drivers/interconnect/Kconfig                |  10 +
 drivers/interconnect/Makefile               |   1 +
 drivers/interconnect/interconnect.c         | 376 ++++++++++++++++++++++++++++
 include/linux/interconnect-consumer.h       |  72 ++++++
 include/linux/interconnect-provider.h       | 120 +++++++++
 8 files changed, 653 insertions(+)
 create mode 100644 Documentation/interconnect/interconnect.rst
 create mode 100644 drivers/interconnect/Kconfig
 create mode 100644 drivers/interconnect/Makefile
 create mode 100644 drivers/interconnect/interconnect.c
 create mode 100644 include/linux/interconnect-consumer.h
 create mode 100644 include/linux/interconnect-provider.h

diff --git a/Documentation/interconnect/interconnect.rst b/Documentation/interconnect/interconnect.rst
new file mode 100644
index 000000000000..a5f8f4576b66
--- /dev/null
+++ b/Documentation/interconnect/interconnect.rst
@@ -0,0 +1,71 @@
+================================================
+GENERIC SYSTEM INTERCONNECT CONTROLLER SUBSYSTEM
+================================================
+
+Introduction
+------------
+
+This framework is designed to provide a standard kernel interface to control
+the settings of the interconnects on a SoC. These settings can be throughput,
+latency and priority between multiple interconnected devices. This can be
+controlled dynamically in order to save power or provide maximum performance.
+
+The interconnect controller is a hardware with configurable parameters, which
+can be set on a data path according to the requests received from various
+drivers. An example of interconnect controllers are the interconnects between
+various components on chipsets. There can be multiple interconnects on a SoC
+that can be multi-tiered.
+
+Below is a simplified diagram of a real-world SoC topology. The interconnect
+providers are the memory front end and the NoCs.
+
+::
+
+ +----------------+    +----------------+
+ | HW Accelerator |--->|      M NoC     |<---------------+
+ +----------------+    +----------------+                |
+                         |      |                    +------------+
+           +-------------+      V       +------+     |            |
+           |                +--------+  | PCIe |     |            |
+           |                | Slaves |  +------+     |            |
+           |                +--------+     |         |   C NoC    |
+           V                               V         |            |
+ +------------------+   +------------------------+   |            |   +-----+
+ |                  |-->|                        |-->|            |-->| CPU |
+ |                  |-->|                        |<--|            |   +-----+
+ |      Memory      |   |         S NoC          |   +------------+
+ |                  |<--|                        |---------+    |
+ |                  |<--|                        |<------+ |    |   +--------+
+ +------------------+   +------------------------+       | |    +-->| Slaves |
+    ^     ^    ^           ^                             | |        +--------+
+    |     |    |           |                             | V
+ +-----+  |  +-----+    +-----+  +---------+   +----------------+   +--------+
+ | CPU |  |  | GPU |    | DSP |  | Masters |-->|       P NoC    |-->| Slaves |
+ +-----+  |  +-----+    +-----+  +---------+   +----------------+   +--------+
+          |
+      +-------+
+      | Modem |
+      +-------+
+
+Interconnect providers
+----------------------
+
+Interconnect provider is an entity that implements methods to initialize and
+configure a interconnect controller hardware.
+
+An interconnect controller should register with the interconnect provider core
+with interconnect_add_provider().
+
+A previously registered interconnect provider is unregistered with
+interconnect_del_provider().
+
+Interconnect consumers
+----------------------
+
+Interconnect consumers are the entities which make use of the data paths exposed
+by the providers. The consumers send requests to providers requesting various
+throughput, latency and priority. Usually the consumers are device drivers, that
+send request based on their needs.
+
+The interconnect framework consumer API functions are documented in
+.. kernel-doc:: include/linux/interconnect-consumer.h
diff --git a/drivers/Kconfig b/drivers/Kconfig
index 505c676fa9c7..930ecde654d5 100644
--- a/drivers/Kconfig
+++ b/drivers/Kconfig
@@ -208,4 +208,6 @@ source "drivers/tee/Kconfig"
 
 source "drivers/mux/Kconfig"
 
+source "drivers/interconnect/Kconfig"
+
 endmenu
diff --git a/drivers/Makefile b/drivers/Makefile
index dfdcda00bfe3..a114b679bb5b 100644
--- a/drivers/Makefile
+++ b/drivers/Makefile
@@ -182,3 +182,4 @@ obj-$(CONFIG_FPGA)		+= fpga/
 obj-$(CONFIG_FSI)		+= fsi/
 obj-$(CONFIG_TEE)		+= tee/
 obj-$(CONFIG_MULTIPLEXER)	+= mux/
+obj-$(CONFIG_INTERCONNECT)	+= interconnect/
diff --git a/drivers/interconnect/Kconfig b/drivers/interconnect/Kconfig
new file mode 100644
index 000000000000..1e50e951cdc1
--- /dev/null
+++ b/drivers/interconnect/Kconfig
@@ -0,0 +1,10 @@
+menuconfig INTERCONNECT
+	tristate "On-Chip Interconnect management support"
+	help
+	  Support for management of the on-chip interconnects.
+
+	  This framework is designed to provide a generic interface for
+          managing the interconnects in a SoC.
+
+	  If unsure, say no.
+
diff --git a/drivers/interconnect/Makefile b/drivers/interconnect/Makefile
new file mode 100644
index 000000000000..d9da6a6c3560
--- /dev/null
+++ b/drivers/interconnect/Makefile
@@ -0,0 +1 @@
+obj-$(CONFIG_INTERCONNECT)  += interconnect.o
diff --git a/drivers/interconnect/interconnect.c b/drivers/interconnect/interconnect.c
new file mode 100644
index 000000000000..5cd98dc97fb8
--- /dev/null
+++ b/drivers/interconnect/interconnect.c
@@ -0,0 +1,376 @@
+/*
+ * Copyright (c) 2017, Linaro Ltd.
+ *
+ * This software is licensed under the terms of the GNU General Public
+ * License version 2, as published by the Free Software Foundation, and
+ * may be copied, distributed, and modified under those terms.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ */
+
+#include <linux/device.h>
+#include <linux/init.h>
+#include <linux/interconnect-consumer.h>
+#include <linux/interconnect-provider.h>
+#include <linux/list.h>
+#include <linux/module.h>
+#include <linux/mutex.h>
+#include <linux/slab.h>
+
+static DEFINE_MUTEX(interconnect_provider_list_mutex);
+static LIST_HEAD(interconnect_provider_list);
+
+/**
+ * struct interconnect_path - interconnect path structure
+ * @num_nodes: number of hops (nodes)
+ * @reqs: array of the requests applicable to this path of nodes
+ */
+struct interconnect_path {
+	size_t num_nodes;
+	struct interconnect_req reqs[0];
+};
+
+static struct interconnect_node *node_find(const char *dev_id, int con_id)
+{
+	struct icp *icp;
+	struct interconnect_node *node = ERR_PTR(-EPROBE_DEFER);
+	int match, best = 0;
+
+	mutex_lock(&interconnect_provider_list_mutex);
+
+	list_for_each_entry(icp, &interconnect_provider_list, icp_list) {
+		struct interconnect_node *n;
+
+		match = 0;
+
+		list_for_each_entry(n, &icp->nodes, icn_list) {
+			if (n->dev_id) {
+				if (!dev_id || strncmp(n->dev_id, dev_id,
+						       strlen(dev_id)))
+					continue;
+				match += 2;
+			}
+			if (n->con_id) {
+				if (!con_id || n->con_id != con_id)
+					continue;
+				match += 1;
+			}
+			if (match > best) {
+				node = n;
+				if (match == 3)
+					goto out;
+
+				best = match;
+			}
+		}
+	}
+
+out:
+	mutex_unlock(&interconnect_provider_list_mutex);
+
+	return node;
+}
+
+static struct interconnect_path *path_allocate(struct interconnect_node *node,
+					       ssize_t num_nodes)
+{
+	struct interconnect_path *path;
+	size_t i;
+
+	path = kzalloc(sizeof(*path) + num_nodes * sizeof(*path->reqs),
+		       GFP_KERNEL);
+	if (!path)
+		return ERR_PTR(-ENOMEM);
+
+	path->num_nodes = num_nodes;
+
+	for (i = 0; i < num_nodes; i++) {
+		hlist_add_head(&path->reqs[i].req_node, &node->req_list);
+
+		/* TODO: populate default values */
+		path->reqs[i].node = node;
+		node = node->reverse;
+	}
+
+	return path;
+}
+
+static struct interconnect_path *path_find(struct interconnect_node *src,
+					   struct interconnect_node *dst)
+{
+	struct list_head edge_list;
+	struct list_head traverse_list;
+	struct list_head tmp_list;
+	struct interconnect_node *node = NULL;
+	size_t i, number = 1;
+	bool found = false;
+
+	INIT_LIST_HEAD(&traverse_list);
+	INIT_LIST_HEAD(&edge_list);
+	INIT_LIST_HEAD(&tmp_list);
+
+	list_add_tail(&src->search_list, &traverse_list);
+
+	do {
+		list_for_each_entry(node, &traverse_list, search_list) {
+			if (node == dst) {
+				found = true;
+				list_add(&node->search_list, &tmp_list);
+				break;
+			}
+			for (i = 0; i < node->num_links; i++) {
+				struct interconnect_node *tmp = node->links[i];
+
+				if (!tmp) {
+					WARN_ON(1);
+					return ERR_PTR(-ENOENT);
+				}
+
+				if (tmp->is_traversed)
+					continue;
+
+				tmp->is_traversed = true;
+				tmp->reverse = node;
+				list_add_tail(&tmp->search_list, &edge_list);
+			}
+		}
+		if (found)
+			break;
+
+		list_splice_init(&traverse_list, &tmp_list);
+		list_splice_init(&edge_list, &traverse_list);
+
+		/* count the number of nodes */
+		number++;
+
+	} while (!list_empty(&traverse_list));
+
+	/* reset the traversed state */
+	list_for_each_entry(node, &tmp_list, search_list) {
+		node->is_traversed = false;
+	}
+
+	if (found)
+		return path_allocate(dst, number);
+
+	return ERR_PTR(-EPROBE_DEFER);
+}
+
+static int path_init(struct interconnect_path *path)
+{
+	struct interconnect_node *node;
+	size_t i;
+
+	for (i = 0; i < path->num_nodes; i++) {
+		node = path->reqs[i].node;
+
+		mutex_lock(&node->icp->lock);
+		node->icp->users++;
+		mutex_unlock(&node->icp->lock);
+	}
+
+	return 0;
+}
+
+static int interconnect_aggregate(struct interconnect_node *node,
+				  struct interconnect_creq *creq)
+{
+	int ret = 0;
+
+	mutex_lock(&node->icp->lock);
+
+	if (node->icp->ops->aggregate) {
+		ret = node->icp->ops->aggregate(node, creq);
+		if (ret) {
+			pr_info("%s: error (%d)\n", __func__, ret);
+			goto out;
+		}
+	} else {
+		/* do not aggregate by default */
+		struct icp *icp = node->icp;
+
+		icp->creq.avg_bw = creq->avg_bw;
+		icp->creq.peak_bw = creq->peak_bw;
+	}
+
+out:
+	mutex_unlock(&node->icp->lock);
+	return ret;
+}
+
+/**
+ * interconnect_set() - set constraints on a path between two endpoints
+ * @path: reference to the path returned by interconnect_get()
+ * @creq: request from the consumer, containing its requirements
+ *
+ * This function is used by an interconnect consumer to express its own needs
+ * in term of bandwidth and QoS for a previously requested path between two
+ * endpoints. The requests are aggregated and each node is updated accordingly.
+ *
+ * Returns 0 on success, or an approproate error code otherwise.
+ */
+int interconnect_set(struct interconnect_path *path,
+		     struct interconnect_creq *creq)
+{
+	struct interconnect_node *next, *prev = NULL;
+	size_t i;
+	int ret = 0;
+
+	for (i = 0; i < path->num_nodes; i++, prev = next) {
+		next = path->reqs[i].node;
+
+		if (!next || !prev)
+			continue;
+
+		if (next->icp != prev->icp)
+			continue;
+
+		/* aggregate requests from consumers */
+		ret = interconnect_aggregate(next, creq);
+		if (ret)
+			goto out;
+
+		if (next->icp->ops->set) {
+			mutex_lock(&next->icp->lock);
+			/* commit the aggregated constraints */
+			ret = next->icp->ops->set(prev, next, &next->icp->creq);
+			mutex_unlock(&next->icp->lock);
+			if (ret)
+				goto out;
+		}
+	}
+
+out:
+	return ret;
+}
+
+/**
+ * interconnect_get() - return a handle for path between two endpoints
+ * @sdev: source device identifier
+ * @sid: source device port id
+ * @ddev: destination device identifier
+ * @did: destination device port id
+ *
+ * This function will search for a path between two endpoints and return an
+ * interconnect_path handle on success. Use interconnect_put() to release
+ * constraints when the they are not needed anymore.
+ *
+ * Return: interconnect_path pointer on success, or ERR_PTR() on error
+ */
+struct interconnect_path *interconnect_get(const char *sdev, const int sid,
+					   const char *ddev, const int did)
+{
+	struct interconnect_node *src, *dst;
+	struct interconnect_path *path;
+	int ret;
+
+	src = node_find(sdev, sid);
+	if (IS_ERR(src))
+		return ERR_CAST(src);
+
+	dst = node_find(ddev, did);
+	if (IS_ERR(dst))
+		return ERR_CAST(dst);
+
+	/* TODO: cache the path */
+	path = path_find(src, dst);
+	if (IS_ERR(path)) {
+		pr_err("error finding path between %p and %p (%ld)\n",
+		       src, dst, PTR_ERR(path));
+		return path;
+	}
+
+	ret = path_init(path);
+	if (ret)
+		return ERR_PTR(ret);
+
+	return path;
+}
+EXPORT_SYMBOL_GPL(interconnect_get);
+
+/**
+ * interconnect_put() - release the reference to the interconnect_path
+ *
+ * @path: interconnect path
+ *
+ * Use this function to release the path and free the memory when setting
+ * constraints on the path is no longer needed.
+ */
+void interconnect_put(struct interconnect_path *path)
+{
+	struct interconnect_creq creq = { 0, 0 };
+	struct interconnect_node *node;
+	size_t i;
+	int ret;
+
+	if (IS_ERR(path))
+		return;
+
+	for (i = 0; i < path->num_nodes; i++) {
+		node = path->reqs[i].node;
+
+		/*
+		 * Remove the constraints from the path,
+		 * update the nodes and free the memory
+		 */
+		ret = interconnect_set(path, &creq);
+		if (ret)
+			pr_err("%s error %d\n", __func__, ret);
+
+		node->icp->users--;
+	}
+
+	kfree(path);
+}
+EXPORT_SYMBOL_GPL(interconnect_put);
+
+/**
+ * interconnect_add_provider() - add a new interconnect provider
+ * @icp: the interconnect provider that will be added into topology
+ *
+ * Return: 0 on success, or an error code otherwise
+ */
+int interconnect_add_provider(struct icp *icp)
+{
+	WARN(!icp->ops->set, "%s: .set is not implemented\n", __func__);
+
+	mutex_lock(&interconnect_provider_list_mutex);
+	mutex_init(&icp->lock);
+	list_add(&icp->icp_list, &interconnect_provider_list);
+	mutex_unlock(&interconnect_provider_list_mutex);
+
+	dev_info(icp->dev, "interconnect provider is added to topology\n");
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(interconnect_add_provider);
+
+/**
+ * interconnect_del_provider() - delete previously added interconnect provider
+ * @icp: the interconnect provider that will be removed from topology
+ *
+ * Return: 0 on success, or an error code otherwise
+ */
+int interconnect_del_provider(struct icp *icp)
+{
+	mutex_lock(&icp->lock);
+	if (icp->users) {
+		mutex_unlock(&icp->lock);
+		return -EBUSY;
+	}
+	mutex_unlock(&icp->lock);
+
+	mutex_lock(&interconnect_provider_list_mutex);
+	list_del(&icp->icp_list);
+	mutex_unlock(&interconnect_provider_list_mutex);
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(interconnect_del_provider);
+
+MODULE_AUTHOR("Georgi Djakov <georgi.djakov@linaro.org");
+MODULE_DESCRIPTION("Interconnect Driver Core");
+MODULE_LICENSE("GPL v2");
diff --git a/include/linux/interconnect-consumer.h b/include/linux/interconnect-consumer.h
new file mode 100644
index 000000000000..c8055f936ff3
--- /dev/null
+++ b/include/linux/interconnect-consumer.h
@@ -0,0 +1,72 @@
+/*
+ * Copyright (c) 2017, Linaro Ltd.
+ *
+ * This software is licensed under the terms of the GNU General Public
+ * License version 2, as published by the Free Software Foundation, and
+ * may be copied, distributed, and modified under those terms.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ */
+
+#ifndef _LINUX_INTERCONNECT_CONSUMER_H
+#define _LINUX_INTERCONNECT_CONSUMER_H
+
+struct interconnect_node;
+struct interconnect_path;
+
+#if IS_ENABLED(CONFIG_INTERCONNECT)
+
+struct interconnect_path *interconnect_get(const char *sdev, const int sid,
+					   const char *ddev, const int did);
+
+void interconnect_put(struct interconnect_path *path);
+
+/**
+ * struct creq - interconnect consumer request
+ * @avg_bw: the average requested bandwidth (over longer period of time) in kbps
+ * @peak_bw: the peak (maximum) bandwidth in kpbs
+ */
+struct interconnect_creq {
+	u32 avg_bw;
+	u32 peak_bw;
+};
+
+/**
+ * interconnect_set() - set constraints on a path between two endpoints
+ * @path: reference to the path returned by interconnect_get()
+ * @creq: request from the consumer, containing its requirements
+ *
+ * This function is used by an interconnect consumer to express its own needs
+ * in term of bandwidth and QoS for a previously requested path between two
+ * endpoints. The requests are aggregated and each node is updated accordingly.
+ *
+ * Returns 0 on success, or an approproate error code otherwise.
+ */
+int interconnect_set(struct interconnect_path *path,
+		     struct interconnect_creq *creq);
+
+#else
+
+inline struct interconnect_path *interconnect_get(const char *sdev,
+							 const int sid,
+							 const char *ddev,
+							 const int did)
+{
+	return ERR_PTR(-ENOTSUPP);
+}
+
+inline void interconnect_put(struct interconnect_path *path)
+{
+}
+
+inline int interconnect_set(struct interconnect_path *path, u32 bandwidth)
+{
+	return -ENOTSUPP
+}
+
+#endif /* CONFIG_INTERCONNECT */
+
+#endif /* _LINUX_INTERCONNECT_CONSUMER_H */
diff --git a/include/linux/interconnect-provider.h b/include/linux/interconnect-provider.h
new file mode 100644
index 000000000000..84b9c7130553
--- /dev/null
+++ b/include/linux/interconnect-provider.h
@@ -0,0 +1,120 @@
+/*
+ * Copyright (c) 2017, Linaro Ltd.
+ *
+ * This software is licensed under the terms of the GNU General Public
+ * License version 2, as published by the Free Software Foundation, and
+ * may be copied, distributed, and modified under those terms.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ */
+
+#ifndef _LINUX_INTERCONNECT_PROVIDER_H
+#define _LINUX_INTERCONNECT_PROVIDER_H
+
+#include <linux/interconnect-consumer.h>
+
+/**
+ * struct icp_ops - platform specific callback operations for interconnect
+ * providers that will be called from drivers
+ *
+ * @aggregate: aggregate constraints with the current configuration
+ * @set: set constraints on interconnect
+ */
+struct icp_ops {
+	int (*aggregate)(struct interconnect_node *node,
+			 struct interconnect_creq *creq);
+	int (*set)(struct interconnect_node *src, struct interconnect_node *dst,
+		   struct interconnect_creq *creq);
+};
+
+/**
+ * struct icp - interconnect provider (controller) entity that might
+ * provide multiple interconnect controls
+ *
+ * @icp_list: list of the registered interconnect providers
+ * @nodes: internal list of the interconnect provider nodes
+ * @ops: pointer to device specific struct icp_ops
+ * @dev: the device this interconnect provider belongs to
+ * @lock: a lock to protect creq and users
+ * @creq: the actual state of constraints for this interconnect provider
+ * @users: count of active users
+ * @data: pointer to private data
+ */
+struct icp {
+	struct list_head	icp_list;
+	struct list_head	nodes;
+	const struct icp_ops	*ops;
+	struct device		*dev;
+	struct mutex		lock;
+	struct interconnect_creq creq;
+	int			users;
+	void			*data;
+};
+
+/**
+ * struct interconnect_node - entity that is part of the interconnect topology
+ *
+ * @links: links to other interconnect nodes
+ * @num_links: number of links to other interconnect nodes
+ * @icp: points to the interconnect provider of this node
+ * @icn_list: list of interconnect nodes
+ * @search_list: list used when walking the nodes graph
+ * @reverse: pointer to previous node when walking the nodes graph
+ * @is_traversed: flag that is used when walking the nodes graph
+ * @req_list: a list of QoS constraint requests
+ * @dev_id: device id
+ * @con_id: connection id
+ */
+struct interconnect_node {
+	struct interconnect_node **links;
+	size_t			num_links;
+
+	struct icp		*icp;
+	struct list_head	icn_list;
+	struct list_head	search_list;
+	struct interconnect_node *reverse;
+	bool			is_traversed;
+	struct hlist_head	req_list;
+
+	const char		*dev_id;
+	int			con_id;
+};
+
+/**
+ * struct interconnect_req - constraints that are attached to each node
+ *
+ * @req_node: the linked list node
+ * @node: the interconnect node to which this constraint applies
+ * @avg_bw: an integer describing the average bandwidth in kbps
+ * @peak_bw: an integer describing the peak bandwidth in kbps
+ */
+struct interconnect_req {
+	struct hlist_node req_node;
+	struct interconnect_node *node;
+	u32 avg_bw;
+	u32 peak_bw;
+};
+
+#if IS_ENABLED(CONFIG_INTERCONNECT)
+
+int interconnect_add_provider(struct icp *icp);
+int interconnect_del_provider(struct icp *icp);
+
+#else
+
+static inline int interconnect_add_provider(struct icp *icp)
+{
+	return -ENOTSUPP;
+}
+
+static inline int interconnect_del_provider(struct icp *icp)
+{
+	return -ENOTSUPP;
+}
+
+#endif /* CONFIG_INTERCONNECT */
+
+#endif /* _LINUX_INTERCONNECT_PROVIDER_H */

[PATCH v1 2/3] interconnect: Add Qualcomm msm8916 interconnect provider driver

[Georgi Djakov]

Add driver for the Qualcomm interconnect controllers found in
msm8916 based platforms. This patch contains only a small part
of the topology to make reviewing easier.

Signed-off-by: Georgi Djakov <georgi.djakov@linaro.org>
---
 drivers/interconnect/Kconfig                     |   5 +
 drivers/interconnect/Makefile                    |   1 +
 drivers/interconnect/qcom/Kconfig                |  12 +
 drivers/interconnect/qcom/Makefile               |   2 +
 drivers/interconnect/qcom/interconnect_msm8916.c | 421 +++++++++++++++++++++++
 include/dt-bindings/interconnect/qcom,msm8916.h  |  87 +++++
 6 files changed, 528 insertions(+)
 create mode 100644 drivers/interconnect/qcom/Kconfig
 create mode 100644 drivers/interconnect/qcom/Makefile
 create mode 100644 drivers/interconnect/qcom/interconnect_msm8916.c
 create mode 100644 include/dt-bindings/interconnect/qcom,msm8916.h

diff --git a/drivers/interconnect/Kconfig b/drivers/interconnect/Kconfig
index 1e50e951cdc1..b123a76e2f9d 100644
--- a/drivers/interconnect/Kconfig
+++ b/drivers/interconnect/Kconfig
@@ -8,3 +8,8 @@ menuconfig INTERCONNECT
 
 	  If unsure, say no.
 
+if INTERCONNECT
+
+source "drivers/interconnect/qcom/Kconfig"
+
+endif
diff --git a/drivers/interconnect/Makefile b/drivers/interconnect/Makefile
index d9da6a6c3560..62a01de24aeb 100644
--- a/drivers/interconnect/Makefile
+++ b/drivers/interconnect/Makefile
@@ -1 +1,2 @@
 obj-$(CONFIG_INTERCONNECT)  += interconnect.o
+obj-$(CONFIG_INTERCONNECT_QCOM)                += qcom/
diff --git a/drivers/interconnect/qcom/Kconfig b/drivers/interconnect/qcom/Kconfig
new file mode 100644
index 000000000000..d96dbf5fd547
--- /dev/null
+++ b/drivers/interconnect/qcom/Kconfig
@@ -0,0 +1,12 @@
+config INTERCONNECT_QCOM
+	bool "Qualcomm Network-on-Chip interconnect drivers"
+	depends on OF
+	depends on ARCH_QCOM || COMPILE_TEST
+	default y
+
+config INTERCONNECT_QCOM_MSM8916
+	tristate "Qualcomm MSM8916 interconnect driver"
+	depends on INTERCONNECT_QCOM
+	help
+	  This is a driver for the Qualcomm Network-on-Chip on msm8916-based platforms.
+
diff --git a/drivers/interconnect/qcom/Makefile b/drivers/interconnect/qcom/Makefile
new file mode 100644
index 000000000000..e5bf8e2b92ac
--- /dev/null
+++ b/drivers/interconnect/qcom/Makefile
@@ -0,0 +1,2 @@
+obj-$(CONFIG_INTERCONNECT_QCOM_MSM8916) += interconnect_msm8916.o
+
diff --git a/drivers/interconnect/qcom/interconnect_msm8916.c b/drivers/interconnect/qcom/interconnect_msm8916.c
new file mode 100644
index 000000000000..8a1cd5ddb3d4
--- /dev/null
+++ b/drivers/interconnect/qcom/interconnect_msm8916.c
@@ -0,0 +1,421 @@
+/*
+ * Copyright (C) 2017 Linaro Ltd
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 and
+ * only version 2 as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ */
+
+#include <asm/div64.h>
+#include <linux/clk.h>
+#include <linux/device.h>
+#include <linux/io.h>
+#include <linux/interconnect-provider.h>
+#include <linux/module.h>
+#include <linux/of_device.h>
+#include <linux/of_platform.h>
+#include <linux/platform_device.h>
+#include <linux/slab.h>
+#include <dt-bindings/interconnect/qcom,msm8916.h>
+
+#define to_qcom_icp(_icp) \
+	container_of(_icp, struct qcom_interconnect_provider, icp)
+#define to_qcom_node(_node) \
+	container_of(_node, struct qcom_interconnect_node, node)
+
+enum qcom_bus_type {
+	QCOM_BUS_TYPE_NOC = 0,
+	QCOM_BUS_TYPE_MEM,
+	QCOM_BUS_TYPE_MAX,
+};
+
+struct qcom_interconnect_provider {
+	struct icp		icp;
+	void __iomem		*base;
+	enum qcom_bus_type	type;
+	u32			base_offset;
+	u32			qos_offset;
+	struct clk		*bus_clk;
+	struct clk		*bus_a_clk;
+};
+
+struct qcom_interconnect_node {
+	struct interconnect_node node;
+	unsigned char *name;
+	struct interconnect_node *links[8];
+	u16 id;
+	u16 num_links;
+	u16 port;
+	u16 buswidth;
+	u64 rate;
+};
+
+static struct qcom_interconnect_node snoc_int_0;
+static struct qcom_interconnect_node snoc_int_1;
+static struct qcom_interconnect_node snoc_int_bimc;
+static struct qcom_interconnect_node snoc_bimc_0_mas;
+static struct qcom_interconnect_node pnoc_snoc_slv;
+
+static struct qcom_interconnect_node snoc_bimc_0_slv;
+static struct qcom_interconnect_node slv_ebi_ch0;
+
+static struct qcom_interconnect_node pnoc_int_1;
+static struct qcom_interconnect_node mas_pnoc_sdcc_1;
+static struct qcom_interconnect_node mas_pnoc_sdcc_2;
+static struct qcom_interconnect_node pnoc_snoc_mas;
+
+struct qcom_interconnect_desc {
+	struct qcom_interconnect_node **nodes;
+	size_t num_nodes;
+};
+
+static struct qcom_interconnect_node snoc_int_0 = {
+	.id = 10004,
+	.name = "snoc-int-0",
+#if 0
+	.links = { &snoc_pnoc_mas.node },
+	.num_links = 1,
+#endif
+	.buswidth = 8,
+};
+
+static struct qcom_interconnect_node snoc_int_1 = {
+	.id = 10005,
+	.name = "snoc-int-1",
+#if 0
+	.links = { &slv_apss.node, &slv_cats_0.node, &slv_cats_1.node },
+	.num_links = 3,
+#endif
+	.buswidth = 8,
+};
+
+static struct qcom_interconnect_node snoc_int_bimc = {
+	.id = 10006,
+	.name = "snoc-bimc",
+	.links = { &snoc_bimc_0_mas.node },
+	.num_links = 1,
+	.buswidth = 8,
+};
+
+static struct qcom_interconnect_node snoc_bimc_0_mas = {
+	.id = 10007,
+	.name = "snoc-bimc-0-mas",
+	.links = { &snoc_bimc_0_slv.node },
+	.num_links = 1,
+	.buswidth = 8,
+};
+
+static struct qcom_interconnect_node pnoc_snoc_slv = {
+	.id = 10011,
+	.name = "snoc-pnoc",
+	.links = { &snoc_int_0.node, &snoc_int_bimc.node, &snoc_int_1.node },
+	.num_links = 3,
+	.buswidth = 8,
+};
+
+static struct qcom_interconnect_node *msm8916_snoc_nodes[] = {
+	[SNOC_INT_0] = &snoc_int_0,
+	[SNOC_INT_1] = &snoc_int_1,
+	[SNOC_INT_BIMC] = &snoc_int_bimc,
+	[SNOC_BIMC_0_MAS] = &snoc_bimc_0_mas,
+	[PNOC_SNOC_SLV] = &pnoc_snoc_slv,
+};
+
+static struct qcom_interconnect_desc msm8916_snoc = {
+	.nodes = msm8916_snoc_nodes,
+	.num_nodes = ARRAY_SIZE(msm8916_snoc_nodes),
+};
+
+static struct qcom_interconnect_node snoc_bimc_0_slv = {
+	.id = 10025,
+	.name = "snoc_bimc_0_slv",
+	.links = { &slv_ebi_ch0.node },
+	.num_links = 1,
+	.buswidth = 8,
+};
+
+static struct qcom_interconnect_node slv_ebi_ch0 = {
+	.id = 512,
+	.name = "slv-ebi-ch0",
+	.buswidth = 8,
+};
+
+static struct qcom_interconnect_node *msm8916_bimc_nodes[] = {
+	[SNOC_BIMC_0_SLV] = &snoc_bimc_0_slv,
+	[SLV_EBI_CH0] = &slv_ebi_ch0,
+};
+
+static struct qcom_interconnect_desc msm8916_bimc = {
+	.nodes = msm8916_bimc_nodes,
+	.num_nodes = ARRAY_SIZE(msm8916_bimc_nodes),
+};
+
+static struct qcom_interconnect_node pnoc_int_1 = {
+	.id = 10013,
+	.name = "pnoc-int-1",
+	.links = { &pnoc_snoc_mas.node },
+	.num_links = 1,
+	.buswidth = 8,
+};
+
+static struct qcom_interconnect_node mas_pnoc_sdcc_1 = {
+	.id = 78,
+	.name = "mas-pnoc-sdcc-1",
+	.links = { &pnoc_int_1.node },
+	.num_links = 1,
+	.port = 7,
+	.buswidth = 8,
+};
+
+static struct qcom_interconnect_node mas_pnoc_sdcc_2 = {
+	.id = 81,
+	.name = "mas-pnoc-sdcc-2",
+	.links = { &pnoc_int_1.node },
+	.num_links = 1,
+	.port = 8,
+	.buswidth = 8,
+};
+
+static struct qcom_interconnect_node pnoc_snoc_mas = {
+	.id = 10010,
+	.name = "pnoc-snoc-mas",
+	.links = { &pnoc_snoc_slv.node },
+	.num_links = 1,
+	.buswidth = 8,
+};
+
+static struct qcom_interconnect_node *msm8916_pnoc_nodes[] = {
+	[PNOC_INT_1] = &pnoc_int_1,
+	[MAS_PNOC_SDCC_1] = &mas_pnoc_sdcc_1,
+	[MAS_PNOC_SDCC_2] = &mas_pnoc_sdcc_2,
+	[PNOC_SNOC_MAS] = &pnoc_snoc_mas,
+};
+
+static struct qcom_interconnect_desc msm8916_pnoc = {
+	.nodes = msm8916_pnoc_nodes,
+	.num_nodes = ARRAY_SIZE(msm8916_pnoc_nodes),
+};
+
+static int qcom_interconnect_init(struct interconnect_node *node)
+{
+	struct qcom_interconnect_node *qn = to_qcom_node(node);
+	int ret = 0;
+
+	/* populate default values */
+	if (!qn->buswidth)
+		qn->buswidth = 8;
+
+	/* TODO: init qos and priority */
+
+	return ret;
+}
+
+static int qcom_interconnect_aggregate(struct interconnect_node *node,
+				       struct interconnect_creq *creq)
+{
+	struct interconnect_node *n;
+	struct interconnect_req *r;
+	struct icp *icp = node->icp;
+	u32 avg_bw = 0;
+	u32 peak_bw = 0;
+
+	list_for_each_entry(n, &node->icp->nodes, icn_list) {
+		hlist_for_each_entry(r, &n->req_list, req_node) {
+			if (n == node) {
+				/* update constraints */
+				r->avg_bw = creq->avg_bw;
+				r->peak_bw = creq->peak_bw;
+			}
+			avg_bw += r->avg_bw;
+			peak_bw = max(peak_bw, r->peak_bw);
+		}
+	}
+
+	/* save the aggregated values */
+	icp->creq.avg_bw = avg_bw;
+	icp->creq.peak_bw = peak_bw;
+
+	return 0;
+}
+
+static int qcom_interconnect_set(struct interconnect_node *src,
+				 struct interconnect_node *dst,
+				 struct interconnect_creq *creq)
+{
+	struct qcom_interconnect_provider *qicp;
+	struct qcom_interconnect_node *qn;
+	struct interconnect_node *node;
+	struct icp *icp;
+	u64 rate = 0;
+	int ret = 0;
+
+	if (!src && !dst)
+		return -ENODEV;
+
+	if (!src)
+		node = dst;
+	else
+		node = src;
+
+	qn = to_qcom_node(node);
+	icp = qn->node.icp;
+	qicp = to_qcom_icp(node->icp);
+
+	rate = max(icp->creq.avg_bw, icp->creq.peak_bw);
+
+	do_div(rate, qn->buswidth);
+
+	if (qn->rate != rate) {
+		ret = clk_set_rate(qicp->bus_clk, rate);
+		if (ret) {
+			pr_err("set clk rate %lld error %d\n", rate, ret);
+			return ret;
+		}
+
+		ret = clk_set_rate(qicp->bus_a_clk, rate);
+		if (ret) {
+			pr_err("set clk rate %lld error %d\n", rate, ret);
+			return ret;
+		}
+
+		qn->rate = rate;
+	}
+
+	return ret;
+}
+
+struct interconnect_onecell_data {
+	struct interconnect_node **nodes;
+	unsigned int num_nodes;
+};
+
+static const struct icp_ops qcom_ops = {
+	.aggregate = qcom_interconnect_aggregate,
+	.set = qcom_interconnect_set,
+};
+
+static int qnoc_probe(struct platform_device *pdev)
+{
+	struct qcom_interconnect_provider *qicp;
+	struct icp *icp;
+	struct device *dev = &pdev->dev;
+	struct device_node *np = dev->of_node;
+	struct resource *res;
+	void __iomem *base;
+	struct clk *bus_clk, *bus_a_clk;
+	size_t num_nodes, i;
+	const struct qcom_interconnect_desc *desc;
+	struct qcom_interconnect_node **qnodes;
+	struct interconnect_node *nodes;
+	struct interconnect_onecell_data *data;
+	u32 type, base_offset, qos_offset = 0;
+
+	desc = of_device_get_match_data(&pdev->dev);
+	if (!desc)
+		return -EINVAL;
+
+	qnodes = desc->nodes;
+	num_nodes = desc->num_nodes;
+
+	qicp = devm_kzalloc(dev, sizeof(*qicp), GFP_KERNEL);
+	if (!qicp)
+		return -ENOMEM;
+
+	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	base = devm_ioremap_resource(dev, res);
+	if (IS_ERR(base))
+		return PTR_ERR(base);
+
+	bus_clk = devm_clk_get(&pdev->dev, "bus_clk");
+	if (IS_ERR(bus_clk))
+		return PTR_ERR(bus_clk);
+	bus_a_clk = devm_clk_get(&pdev->dev, "bus_a_clk");
+	if (IS_ERR(bus_a_clk))
+		return PTR_ERR(bus_a_clk);
+
+	of_property_read_u32(np, "type", &type);
+	of_property_read_u32(np, "base-offset", &base_offset);
+	of_property_read_u32(np, "qos-offset", &qos_offset);
+
+	qicp->base = base;
+	qicp->type = type;
+	qicp->base_offset = base_offset;
+	qicp->qos_offset = qos_offset;
+	qicp->bus_clk = bus_clk;
+	qicp->bus_a_clk = bus_a_clk;
+	icp = &qicp->icp;
+	icp->dev = dev;
+	icp->ops = &qcom_ops;
+	INIT_LIST_HEAD(&icp->nodes);
+
+	data = devm_kzalloc(dev, sizeof(*data), GFP_KERNEL);
+	if (!data)
+		return -ENOMEM;
+
+	icp->data = data;
+	data->num_nodes = num_nodes;
+
+	data->nodes = devm_kcalloc(dev, num_nodes, sizeof(*nodes), GFP_KERNEL);
+	if (!data->nodes)
+		return -ENOMEM;
+
+	for (i = 0; i < num_nodes; i++) {
+		struct interconnect_node *node;
+		int ret;
+		size_t j;
+
+		if (!qnodes[i])
+			continue;
+
+		node = &qnodes[i]->node;
+		node->dev_id = kstrdup_const(qnodes[i]->name, GFP_KERNEL);
+		node->con_id = qnodes[i]->id;
+		node->icp = icp;
+		node->num_links = qnodes[i]->num_links;
+		node->links = devm_kcalloc(dev, node->num_links,
+				sizeof(*node->links), GFP_KERNEL);
+		if (!node->links)
+			return -ENOMEM;
+
+		/* populate links */
+		for (j = 0; j < node->num_links; j++)
+			node->links[j] = qnodes[i]->links[j];
+
+		/* add node to interconnect provider */
+		data->nodes[i] = node;
+		list_add_tail(&node->icn_list, &icp->nodes);
+		dev_dbg(&pdev->dev, "registered node %p %s %d\n", node,
+			node->dev_id, node->con_id);
+
+		ret = qcom_interconnect_init(node);
+		if (ret)
+			dev_err(&pdev->dev, "node init error (%d)\n", ret);
+	}
+
+	return interconnect_add_provider(icp);
+}
+
+static const struct of_device_id qnoc_of_match[] = {
+	{ .compatible = "qcom,msm-bus-pnoc", .data = &msm8916_pnoc },
+	{ .compatible = "qcom,msm-bus-snoc", .data = &msm8916_snoc },
+	{ .compatible = "qcom,msm-bus-bimc", .data = &msm8916_bimc },
+	{ },
+};
+MODULE_DEVICE_TABLE(of, qnoc_of_match);
+
+static struct platform_driver qnoc_driver = {
+	.probe = qnoc_probe,
+	.driver = {
+		.name = "qcom,qnoc",
+		.of_match_table = qnoc_of_match,
+	},
+};
+module_platform_driver(qnoc_driver);
+MODULE_AUTHOR("Georgi Djakov <georgi.djakov@linaro.org>");
+MODULE_DESCRIPTION("Qualcomm msm8916 NoC driver");
+MODULE_LICENSE("GPL v2");
diff --git a/include/dt-bindings/interconnect/qcom,msm8916.h b/include/dt-bindings/interconnect/qcom,msm8916.h
new file mode 100644
index 000000000000..ea772b34ac96
--- /dev/null
+++ b/include/dt-bindings/interconnect/qcom,msm8916.h
@@ -0,0 +1,87 @@
+#define MAS_VIDEO				0
+#define MAS_JPEG				1
+#define MAS_VFE					2
+#define MAS_MDP					3
+#define MAS_QDSS_BAM				4
+#define MAS_SNOC_CFG				5
+#define MAS_QDSS_ETR				6
+#define MM_INT_0				7
+#define MM_INT_1				8
+#define MM_INT_2				9
+#define MM_INT_BIMC				10
+#define SNOC_INT_0				11
+#define SNOC_INT_1				12
+#define SNOC_INT_BIMC				13
+#define SNOC_BIMC_0_MAS				14
+#define SNOC_BIMC_1_MAS				15
+#define QDSS_INT				16
+#define BIMC_SNOC_SLV				17
+#define SNOC_PNOC_MAS				18
+#define PNOC_SNOC_SLV				19
+#define SLV_SRVC_SNOC				20
+#define SLV_QDSS_STM				21
+#define SLV_IMEM				22
+#define SLV_APSS				23
+#define SLV_CATS_0				24
+#define SLV_CATS_1				25
+
+#define MAS_APPS				0
+#define MAS_TCU0				1
+#define MAS_TCU1				2
+#define MAS_GFX					3
+#define BIMC_SNOC_MAS				4
+#define SNOC_BIMC_0_SLV				5
+#define SNOC_BIMC_1_SLV				6
+#define SLV_EBI_CH0				7
+#define SLV_APPS_L2				8
+
+#define SNOC_PNOC_SLV				0
+#define PNOC_INT_0				1
+#define PNOC_INT_1				2
+#define PNOC_M_0				3
+#define PNOC_M_1				4
+#define PNOC_S_0				5
+#define PNOC_S_1				6
+#define PNOC_S_2				7
+#define PNOC_S_3				8
+#define PNOC_S_4				9
+#define PNOC_S_8				10
+#define PNOC_S_9				11
+#define SLV_IMEM_CFG				12
+#define SLV_CRYPTO_0_CFG			13
+#define SLV_MSG_RAM				14
+#define SLV_PDM					15
+#define SLV_PRNG				16
+#define SLV_CLK_CTL				17
+#define SLV_MSS					18
+#define SLV_TLMM				19
+#define SLV_TCSR				20
+#define SLV_SECURITY				21
+#define SLV_SPDM				22
+#define SLV_PNOC_CFG				23
+#define SLV_PMIC_ARB				24
+#define SLV_BIMC_CFG				25
+#define SLV_BOOT_ROM				26
+#define SLV_MPM					27
+#define SLV_QDSS_CFG				28
+#define SLV_RBCPR_CFG				29
+#define SLV_SNOC_CFG				30
+#define SLV_DEHR_CFG				31
+#define SLV_VENUS_CFG				32
+#define SLV_DISPLAY_CFG				33
+#define SLV_CAMERA_CFG				34
+#define SLV_USB_HS				35
+#define SLV_SDCC_1				36
+#define SLV_BLSP_1				37
+#define SLV_SDCC_2				38
+#define SLV_GFX_CFG				39
+#define SLV_AUDIO				40
+#define MAS_BLSP_1				41
+#define MAS_SPDM				42
+#define MAS_DEHR				43
+#define MAS_AUDIO				44
+#define MAS_USB_HS				45
+#define MAS_PNOC_CRYPTO_0			46
+#define MAS_PNOC_SDCC_1				47
+#define MAS_PNOC_SDCC_2				48
+#define PNOC_SNOC_MAS				49

[PATCH v1 3/3] dt-bindings: Interconnect device-tree bindings draft

[Georgi Djakov]

The interconnect API is not yet using DT bindings for expressing
the relations between the API consumers and providers. This is
posted a separate patch as it needs further discussions on how
to represent this with DT.

Signed-off-by: Georgi Djakov <georgi.djakov@linaro.org>
---
 .../bindings/interconnect/interconnect.txt         | 75 ++++++++++++++++++++++
 1 file changed, 75 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/interconnect/interconnect.txt

diff --git a/Documentation/devicetree/bindings/interconnect/interconnect.txt b/Documentation/devicetree/bindings/interconnect/interconnect.txt
new file mode 100644
index 000000000000..e38a29db981e
--- /dev/null
+++ b/Documentation/devicetree/bindings/interconnect/interconnect.txt
@@ -0,0 +1,75 @@
+Interconnect Provider Device Tree Bindings
+=========================================
+
+The purpose of this document is to define a common set of generic interconnect
+providers/consumers properties.
+
+
+= interconnect providers =
+
+The interconnect provider binding is intended to represent the interconnect
+controllers in the system. Each provider registers a set of interconnect
+nodes, which expose the interconnect related capabilities of the interconnect
+to consumer drivers. These capabilities can be throughput, latency, priority
+etc. The consumer drivers set constraints on interconnect path (or endpoints)
+depending on the usecase. Interconnect providers can also be interconnect
+consumers, such as in the case where two network-on-chip fabrics interface
+directly
+
+Required properties:
+- compatible : contains the interconnect provider vendor specific compatible
+	       string
+- reg : register space of the interconnect controller hardware
+- #interconnect-cells : number of cells in a interconnect specifier needed to
+		       encode the interconnect node id.
+
+Example:
+
+		snoc: snoc@0580000 {
+			compatible = "qcom,msm-bus-snoc";
+			reg = <0x580000 0x14000>;
+			#interconnect-cells = <1>;
+			clock-names = "bus_clk", "bus_a_clk";
+			clocks = <&rpmcc RPM_SMD_SNOC_CLK>, <&rpmcc RPM_SMD_SNOC_A_CLK>;
+			status = "okay";
+		};
+		bimc: bimc@0400000 {
+			compatible = "qcom,msm-bus-bimc";
+			reg = <0x400000 0x62000>;
+			#interconnect-cells = <1>;
+			clock-names = "bus_clk", "bus_a_clk";
+			clocks = <&rpmcc RPM_SMD_BIMC_CLK>, <&rpmcc RPM_SMD_BIMC_A_CLK>;
+			status = "okay";
+		};
+		pnoc: pnoc@500000 {
+			compatible = "qcom,msm-bus-pnoc";
+			reg = <0x500000 0x11000>;
+			#interconnect-cells = <1>;
+			clock-names = "bus_clk", "bus_a_clk";
+			clocks = <&rpmcc RPM_SMD_PCNOC_CLK>, <&rpmcc RPM_SMD_PCNOC_A_CLK>;
+			status = "okay";
+		};
+
+= interconnect consumers =
+
+The interconnect consumers are device nodes which consume the interconnect
+path(s) provided by the interconnect provider. There can be multiple
+interconnect providers on a SoC and the consumer may consume multiple paths
+from different providers depending on usecase and the components it has to
+interact with.
+
+Required-properties:
+interconnect-src : A phandle and interconnect provider specifier as defined by
+		bindings of the interconnect provider specified by phandle.
+		This denotes the source device port which will be used, as the
+		device may have multiple master ports.
+interconnect-dst : A phandle and internet provider specifier pointing to the
+		local port of the target device.
+
+Example:
+
+	sdhci@07864000 {
+		...
+		interconnect-src = <&pnoc MAS_PNOC_SDCC_2>;
+		interconnect-dst = <&pnoc SLV_BLSP_1>;
+	};

Re: [PATCH v1 1/3] interconnect: Add generic interconnect controller API

[Vincent Guittot]

Hi Georgi,

On 27 June 2017 at 19:49, Georgi Djakov <georgi.djakov@linaro.org> wrote:

[snip]

> +
> +static int interconnect_aggregate(struct interconnect_node *node,
> +                                 struct interconnect_creq *creq)
> +{
> +       int ret = 0;
> +
> +       mutex_lock(&node->icp->lock);
> +
> +       if (node->icp->ops->aggregate) {
> +               ret = node->icp->ops->aggregate(node, creq);
> +               if (ret) {
> +                       pr_info("%s: error (%d)\n", __func__, ret);
> +                       goto out;
> +               }
> +       } else {
> +               /* do not aggregate by default */
> +               struct icp *icp = node->icp;
> +
> +               icp->creq.avg_bw = creq->avg_bw;
> +               icp->creq.peak_bw = creq->peak_bw;

Does it means that by default the last caller defines the bandwidth
for everybody ?
IMHO, having a default aggregation policy that sums the avg_bw of all
request of the node
and that gets the max of peak_bw of all request of a node is better

> +       }
> +
> +out:
> +       mutex_unlock(&node->icp->lock);
> +       return ret;
> +}
> +
> +/**
> + * interconnect_set() - set constraints on a path between two endpoints
> + * @path: reference to the path returned by interconnect_get()
> + * @creq: request from the consumer, containing its requirements
> + *
> + * This function is used by an interconnect consumer to express its own needs
> + * in term of bandwidth and QoS for a previously requested path between two
> + * endpoints. The requests are aggregated and each node is updated accordingly.
> + *
> + * Returns 0 on success, or an approproate error code otherwise.
> + */
> +int interconnect_set(struct interconnect_path *path,
> +                    struct interconnect_creq *creq)
> +{
> +       struct interconnect_node *next, *prev = NULL;
> +       size_t i;
> +       int ret = 0;
> +
> +       for (i = 0; i < path->num_nodes; i++, prev = next) {
> +               next = path->reqs[i].node;
> +
> +               if (!next || !prev)

This needs a comment with an explanation about why you don't do
anything in this case

> +                       continue;
> +
> +               if (next->icp != prev->icp)

This needs a comment with an explanation about why you don't do
anything in this case

> +                       continue;
> +
> +               /* aggregate requests from consumers */

you should update the path->reqs[i].avg_bw and path->reqs[i].peak_bw
with creq values
before aggregating the requests from the different consumer of a node ?

              path->reqs[i].avg_bw = creq->avg_bw
              path->reqs[i].peak_bw = creq->peak_bw

> +               ret = interconnect_aggregate(next, creq);
> +               if (ret)
> +                       goto out;
> +
> +               if (next->icp->ops->set) {
> +                       mutex_lock(&next->icp->lock);
> +                       /* commit the aggregated constraints */
> +                       ret = next->icp->ops->set(prev, next, &next->icp->creq);
> +                       mutex_unlock(&next->icp->lock);
> +                       if (ret)
> +                               goto out;
> +               }
> +       }
> +
> +out:
> +       return ret;
> +}
> +
> +/**
> + * interconnect_get() - return a handle for path between two endpoints
> + * @sdev: source device identifier
> + * @sid: source device port id
> + * @ddev: destination device identifier
> + * @did: destination device port id
> + *
> + * This function will search for a path between two endpoints and return an
> + * interconnect_path handle on success. Use interconnect_put() to release
> + * constraints when the they are not needed anymore.
> + *
> + * Return: interconnect_path pointer on success, or ERR_PTR() on error
> + */
> +struct interconnect_path *interconnect_get(const char *sdev, const int sid,
> +                                          const char *ddev, const int did)
> +{
> +       struct interconnect_node *src, *dst;
> +       struct interconnect_path *path;
> +       int ret;
> +
> +       src = node_find(sdev, sid);
> +       if (IS_ERR(src))
> +               return ERR_CAST(src);
> +
> +       dst = node_find(ddev, did);
> +       if (IS_ERR(dst))
> +               return ERR_CAST(dst);
> +
> +       /* TODO: cache the path */
> +       path = path_find(src, dst);
> +       if (IS_ERR(path)) {
> +               pr_err("error finding path between %p and %p (%ld)\n",
> +                      src, dst, PTR_ERR(path));
> +               return path;
> +       }
> +
> +       ret = path_init(path);
> +       if (ret)
> +               return ERR_PTR(ret);
> +
> +       return path;
> +}
> +EXPORT_SYMBOL_GPL(interconnect_get);
> +
> +/**
> + * interconnect_put() - release the reference to the interconnect_path
> + *
> + * @path: interconnect path
> + *
> + * Use this function to release the path and free the memory when setting
> + * constraints on the path is no longer needed.
> + */
> +void interconnect_put(struct interconnect_path *path)
> +{
> +       struct interconnect_creq creq = { 0, 0 };
> +       struct interconnect_node *node;
> +       size_t i;
> +       int ret;
> +
> +       if (IS_ERR(path))
> +               return;
> +
> +       for (i = 0; i < path->num_nodes; i++) {
> +               node = path->reqs[i].node;
> +
> +               /*
> +                * Remove the constraints from the path,
> +                * update the nodes and free the memory
> +                */
> +               ret = interconnect_set(path, &creq);
> +               if (ret)
> +                       pr_err("%s error %d\n", __func__, ret);
> +
> +               node->icp->users--;
> +       }
> +
> +       kfree(path);
> +}
> +EXPORT_SYMBOL_GPL(interconnect_put);
> +
> +/**
> + * interconnect_add_provider() - add a new interconnect provider
> + * @icp: the interconnect provider that will be added into topology
> + *
> + * Return: 0 on success, or an error code otherwise
> + */
> +int interconnect_add_provider(struct icp *icp)
> +{
> +       WARN(!icp->ops->set, "%s: .set is not implemented\n", __func__);
> +
> +       mutex_lock(&interconnect_provider_list_mutex);
> +       mutex_init(&icp->lock);
> +       list_add(&icp->icp_list, &interconnect_provider_list);
> +       mutex_unlock(&interconnect_provider_list_mutex);
> +
> +       dev_info(icp->dev, "interconnect provider is added to topology\n");
> +
> +       return 0;
> +}
> +EXPORT_SYMBOL_GPL(interconnect_add_provider);
> +
> +/**
> + * interconnect_del_provider() - delete previously added interconnect provider
> + * @icp: the interconnect provider that will be removed from topology
> + *
> + * Return: 0 on success, or an error code otherwise
> + */
> +int interconnect_del_provider(struct icp *icp)
> +{
> +       mutex_lock(&icp->lock);
> +       if (icp->users) {
> +               mutex_unlock(&icp->lock);
> +               return -EBUSY;
> +       }
> +       mutex_unlock(&icp->lock);
> +
> +       mutex_lock(&interconnect_provider_list_mutex);
> +       list_del(&icp->icp_list);
> +       mutex_unlock(&interconnect_provider_list_mutex);
> +
> +       return 0;
> +}
> +EXPORT_SYMBOL_GPL(interconnect_del_provider);
> +
> +MODULE_AUTHOR("Georgi Djakov <georgi.djakov@linaro.org");
> +MODULE_DESCRIPTION("Interconnect Driver Core");
> +MODULE_LICENSE("GPL v2");
> diff --git a/include/linux/interconnect-consumer.h b/include/linux/interconnect-consumer.h
> new file mode 100644
> index 000000000000..c8055f936ff3
> --- /dev/null
> +++ b/include/linux/interconnect-consumer.h
> @@ -0,0 +1,72 @@
> +/*
> + * Copyright (c) 2017, Linaro Ltd.
> + *
> + * This software is licensed under the terms of the GNU General Public
> + * License version 2, as published by the Free Software Foundation, and
> + * may be copied, distributed, and modified under those terms.
> + *
> + * This program is distributed in the hope that it will be useful,
> + * but WITHOUT ANY WARRANTY; without even the implied warranty of
> + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
> + * GNU General Public License for more details.
> + */
> +
> +#ifndef _LINUX_INTERCONNECT_CONSUMER_H
> +#define _LINUX_INTERCONNECT_CONSUMER_H
> +
> +struct interconnect_node;
> +struct interconnect_path;
> +
> +#if IS_ENABLED(CONFIG_INTERCONNECT)
> +
> +struct interconnect_path *interconnect_get(const char *sdev, const int sid,
> +                                          const char *ddev, const int did);
> +
> +void interconnect_put(struct interconnect_path *path);
> +
> +/**
> + * struct creq - interconnect consumer request
> + * @avg_bw: the average requested bandwidth (over longer period of time) in kbps
> + * @peak_bw: the peak (maximum) bandwidth in kpbs
> + */
> +struct interconnect_creq {
> +       u32 avg_bw;
> +       u32 peak_bw;
> +};
> +
> +/**
> + * interconnect_set() - set constraints on a path between two endpoints
> + * @path: reference to the path returned by interconnect_get()
> + * @creq: request from the consumer, containing its requirements
> + *
> + * This function is used by an interconnect consumer to express its own needs
> + * in term of bandwidth and QoS for a previously requested path between two
> + * endpoints. The requests are aggregated and each node is updated accordingly.
> + *
> + * Returns 0 on success, or an approproate error code otherwise.
> + */
> +int interconnect_set(struct interconnect_path *path,
> +                    struct interconnect_creq *creq);
> +
> +#else
> +
> +inline struct interconnect_path *interconnect_get(const char *sdev,
> +                                                        const int sid,
> +                                                        const char *ddev,
> +                                                        const int did)
> +{
> +       return ERR_PTR(-ENOTSUPP);
> +}
> +
> +inline void interconnect_put(struct interconnect_path *path)
> +{
> +}
> +
> +inline int interconnect_set(struct interconnect_path *path, u32 bandwidth)
> +{
> +       return -ENOTSUPP
> +}
> +
> +#endif /* CONFIG_INTERCONNECT */
> +
> +#endif /* _LINUX_INTERCONNECT_CONSUMER_H */
> diff --git a/include/linux/interconnect-provider.h b/include/linux/interconnect-provider.h
> new file mode 100644
> index 000000000000..84b9c7130553
> --- /dev/null
> +++ b/include/linux/interconnect-provider.h
> @@ -0,0 +1,120 @@
> +/*
> + * Copyright (c) 2017, Linaro Ltd.
> + *
> + * This software is licensed under the terms of the GNU General Public
> + * License version 2, as published by the Free Software Foundation, and
> + * may be copied, distributed, and modified under those terms.
> + *
> + * This program is distributed in the hope that it will be useful,
> + * but WITHOUT ANY WARRANTY; without even the implied warranty of
> + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
> + * GNU General Public License for more details.
> + */
> +
> +#ifndef _LINUX_INTERCONNECT_PROVIDER_H
> +#define _LINUX_INTERCONNECT_PROVIDER_H
> +
> +#include <linux/interconnect-consumer.h>
> +
> +/**
> + * struct icp_ops - platform specific callback operations for interconnect
> + * providers that will be called from drivers
> + *
> + * @aggregate: aggregate constraints with the current configuration
> + * @set: set constraints on interconnect
> + */
> +struct icp_ops {
> +       int (*aggregate)(struct interconnect_node *node,
> +                        struct interconnect_creq *creq);
> +       int (*set)(struct interconnect_node *src, struct interconnect_node *dst,
> +                  struct interconnect_creq *creq);
> +};
> +
> +/**
> + * struct icp - interconnect provider (controller) entity that might
> + * provide multiple interconnect controls
> + *
> + * @icp_list: list of the registered interconnect providers
> + * @nodes: internal list of the interconnect provider nodes
> + * @ops: pointer to device specific struct icp_ops
> + * @dev: the device this interconnect provider belongs to
> + * @lock: a lock to protect creq and users
> + * @creq: the actual state of constraints for this interconnect provider
> + * @users: count of active users
> + * @data: pointer to private data
> + */
> +struct icp {
> +       struct list_head        icp_list;
> +       struct list_head        nodes;
> +       const struct icp_ops    *ops;
> +       struct device           *dev;
> +       struct mutex            lock;
> +       struct interconnect_creq creq;
> +       int                     users;
> +       void                    *data;
> +};
> +
> +/**
> + * struct interconnect_node - entity that is part of the interconnect topology
> + *
> + * @links: links to other interconnect nodes
> + * @num_links: number of links to other interconnect nodes
> + * @icp: points to the interconnect provider of this node
> + * @icn_list: list of interconnect nodes
> + * @search_list: list used when walking the nodes graph
> + * @reverse: pointer to previous node when walking the nodes graph
> + * @is_traversed: flag that is used when walking the nodes graph
> + * @req_list: a list of QoS constraint requests
> + * @dev_id: device id
> + * @con_id: connection id
> + */
> +struct interconnect_node {
> +       struct interconnect_node **links;
> +       size_t                  num_links;
> +
> +       struct icp              *icp;
> +       struct list_head        icn_list;
> +       struct list_head        search_list;
> +       struct interconnect_node *reverse;
> +       bool                    is_traversed;
> +       struct hlist_head       req_list;
> +
> +       const char              *dev_id;
> +       int                     con_id;
> +};
> +
> +/**
> + * struct interconnect_req - constraints that are attached to each node
> + *
> + * @req_node: the linked list node
> + * @node: the interconnect node to which this constraint applies
> + * @avg_bw: an integer describing the average bandwidth in kbps
> + * @peak_bw: an integer describing the peak bandwidth in kbps
> + */
> +struct interconnect_req {
> +       struct hlist_node req_node;
> +       struct interconnect_node *node;
> +       u32 avg_bw;
> +       u32 peak_bw;
> +};
> +
> +#if IS_ENABLED(CONFIG_INTERCONNECT)
> +
> +int interconnect_add_provider(struct icp *icp);
> +int interconnect_del_provider(struct icp *icp);
> +
> +#else
> +
> +static inline int interconnect_add_provider(struct icp *icp)
> +{
> +       return -ENOTSUPP;
> +}
> +
> +static inline int interconnect_del_provider(struct icp *icp)
> +{
> +       return -ENOTSUPP;
> +}
> +
> +#endif /* CONFIG_INTERCONNECT */
> +
> +#endif /* _LINUX_INTERCONNECT_PROVIDER_H */

Re: [PATCH v1 3/3] dt-bindings: Interconnect device-tree bindings draft

[Rob Herring]

On Tue, Jun 27, 2017 at 08:49:03PM +0300, Georgi Djakov wrote:
> The interconnect API is not yet using DT bindings for expressing
> the relations between the API consumers and providers. This is
> posted a separate patch as it needs further discussions on how
> to represent this with DT.

I would recommend continuing to sort out how this works within the 
kernel before fixing things in DT. Something like this needs to be a 
core binding in the DT spec.

Also, you should CC some ARM, Ltd. folks like Mark R and Lorenzo. 
There's been some discussion in the past how to describe the DMA master 
side of the bus topology.

Rob

Re: [PATCH v1 1/3] interconnect: Add generic interconnect controller API

[Georgi Djakov]

Hi Vincent,

On 06/28/2017 08:45 PM, Vincent Guittot wrote:
> Hi Georgi,
> 
> On 27 June 2017 at 19:49, Georgi Djakov <georgi.djakov@linaro.org> wrote:
> 
> [snip]
> 
>> +
>> +static int interconnect_aggregate(struct interconnect_node *node,
>> +                                 struct interconnect_creq *creq)
>> +{
>> +       int ret = 0;
>> +
>> +       mutex_lock(&node->icp->lock);
>> +
>> +       if (node->icp->ops->aggregate) {
>> +               ret = node->icp->ops->aggregate(node, creq);
>> +               if (ret) {
>> +                       pr_info("%s: error (%d)\n", __func__, ret);
>> +                       goto out;
>> +               }
>> +       } else {
>> +               /* do not aggregate by default */
>> +               struct icp *icp = node->icp;
>> +
>> +               icp->creq.avg_bw = creq->avg_bw;
>> +               icp->creq.peak_bw = creq->peak_bw;
> 
> Does it means that by default the last caller defines the bandwidth
> for everybody ?
> IMHO, having a default aggregation policy that sums the avg_bw of all
> request of the node
> and that gets the max of peak_bw of all request of a node is better
> 

Yes, i had this in one of the previous versions, but then i removed the
aggregation by default. Will put it back. Thanks!

>> +       }
>> +
>> +out:
>> +       mutex_unlock(&node->icp->lock);
>> +       return ret;
>> +}
>> +
>> +/**
>> + * interconnect_set() - set constraints on a path between two endpoints
>> + * @path: reference to the path returned by interconnect_get()
>> + * @creq: request from the consumer, containing its requirements
>> + *
>> + * This function is used by an interconnect consumer to express its own needs
>> + * in term of bandwidth and QoS for a previously requested path between two
>> + * endpoints. The requests are aggregated and each node is updated accordingly.
>> + *
>> + * Returns 0 on success, or an approproate error code otherwise.
>> + */
>> +int interconnect_set(struct interconnect_path *path,
>> +                    struct interconnect_creq *creq)
>> +{
>> +       struct interconnect_node *next, *prev = NULL;
>> +       size_t i;
>> +       int ret = 0;
>> +
>> +       for (i = 0; i < path->num_nodes; i++, prev = next) {
>> +               next = path->reqs[i].node;
>> +
>> +               if (!next || !prev)
> 
> This needs a comment with an explanation about why you don't do
> anything in this case

Ok.

> 
>> +                       continue;
>> +
>> +               if (next->icp != prev->icp)
> 
> This needs a comment with an explanation about why you don't do
> anything in this case

Ok.

> 
>> +                       continue;
>> +
>> +               /* aggregate requests from consumers */
> 
> you should update the path->reqs[i].avg_bw and path->reqs[i].peak_bw
> with creq values
> before aggregating the requests from the different consumer of a node ?
> 
>               path->reqs[i].avg_bw = creq->avg_bw
>               path->reqs[i].peak_bw = creq->peak_bw

I am updating them currently in the vendor implementation of the
aggregate() function, but this was probably not the right place,
so i will move it here instead. Thanks for the comments!

BR,
Georgi

Re: [PATCH v1 3/3] dt-bindings: Interconnect device-tree bindings draft

[Georgi Djakov]

Hi Rob,

On 06/30/2017 12:32 AM, Rob Herring wrote:
> On Tue, Jun 27, 2017 at 08:49:03PM +0300, Georgi Djakov wrote:
>> The interconnect API is not yet using DT bindings for expressing
>> the relations between the API consumers and providers. This is
>> posted a separate patch as it needs further discussions on how
>> to represent this with DT.
> 
> I would recommend continuing to sort out how this works within the 
> kernel before fixing things in DT. Something like this needs to be a 
> core binding in the DT spec.

Yes, that's the plan. Do you prefer me to drop this patch for now?

> 
> Also, you should CC some ARM, Ltd. folks like Mark R and Lorenzo. 
> There's been some discussion in the past how to describe the DMA master 
> side of the bus topology.

Thanks for the information! I will CC them on the next version!

BR,
Georgi