[PATCH v3 0/3] Introduce on-chip interconnect API

[PATCH v3 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 buses 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 NoCs.

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

This patchset 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.
 * Replace dev_id string names resource lookups with integer ids.

Summary of the patches:
Patch 1 introduces the interconnect API.
Patch 2 add basic support for tracepoints
Patch 3 creates the first vendor specific interconnect bus driver.

Changes since patchset v2 (https://lkml.org/lkml/2017/7/20/825)
* Split the aggregation into per node and per provider. Cache the
  aggregated values.
* Various small refactorings and cleanups in the framework.
* Added a patch introducing basic tracepoint support for monitoring
  the time required to update the interconnect nodes.

Changes since patchset v1 (https://lkml.org/lkml/2017/6/27/890)
* Updates in the documentation.
* Changes in request aggregation, locking.
* Dropped the aggregate() callback and use the default as it currently
  sufficient for the single vendor driver. Will add it later when needed.
* Dropped the dt-bindings draft patch for now.

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 on-chip interconnect API
  interconnect: Add basic event tracing
  interconnect: Add Qualcomm msm8916 interconnect provider driver

 Documentation/interconnect/interconnect.rst      |  93 ++++++
 drivers/Kconfig                                  |   2 +
 drivers/Makefile                                 |   1 +
 drivers/interconnect/Kconfig                     |  15 +
 drivers/interconnect/Makefile                    |   2 +
 drivers/interconnect/interconnect.c              | 389 +++++++++++++++++++++++
 drivers/interconnect/qcom/Kconfig                |  11 +
 drivers/interconnect/qcom/Makefile               |   1 +
 drivers/interconnect/qcom/interconnect_msm8916.c | 375 ++++++++++++++++++++++
 include/linux/interconnect-consumer.h            |  73 +++++
 include/linux/interconnect-provider.h            | 119 +++++++
 include/linux/interconnect/qcom-msm8916.h        |  92 ++++++
 include/trace/events/interconnect.h              |  45 +++
 13 files changed, 1218 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 drivers/interconnect/qcom/Kconfig
 create mode 100644 drivers/interconnect/qcom/Makefile
 create mode 100644 drivers/interconnect/qcom/interconnect_msm8916.c
 create mode 100644 include/linux/interconnect-consumer.h
 create mode 100644 include/linux/interconnect-provider.h
 create mode 100644 include/linux/interconnect/qcom-msm8916.h
 create mode 100644 include/trace/events/interconnect.h

[PATCH v3 1/3] interconnect: Add generic on-chip interconnect API

[Georgi Djakov]

This patch introduce a new API to get requirements 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 buses and the consumers could be various drivers.
The consumers request interconnect resources (path) between endpoints and
set the desired constraints on this data flow path. The providers 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 |  93 +++++++
 drivers/Kconfig                             |   2 +
 drivers/Makefile                            |   1 +
 drivers/interconnect/Kconfig                |  10 +
 drivers/interconnect/Makefile               |   1 +
 drivers/interconnect/interconnect.c         | 382 ++++++++++++++++++++++++++++
 include/linux/interconnect-consumer.h       |  73 ++++++
 include/linux/interconnect-provider.h       | 119 +++++++++
 8 files changed, 681 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..b057e9c12d70
--- /dev/null
+++ b/Documentation/interconnect/interconnect.rst
@@ -0,0 +1,93 @@
+=====================================
+GENERIC SYSTEM INTERCONNECT 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 bus 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 buses 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 interconnect bus topology.
+
+::
+
+ +----------------+    +----------------+
+ | HW Accelerator |--->|      M NoC     |<---------------+
+ +----------------+    +----------------+                |
+                         |      |                    +------------+
+  +-----+  +-------------+      V       +------+     |            |
+  | DDR |  |                +--------+  | PCIe |     |            |
+  +-----+  |                | Slaves |  +------+     |            |
+    ^ ^    |                +--------+     |         |   C NoC    |
+    | |    V                               V         |            |
+ +------------------+   +------------------------+   |            |   +-----+
+ |                  |-->|                        |-->|            |-->| CPU |
+ |                  |-->|                        |<--|            |   +-----+
+ |     Mem NoC      |   |         S NoC          |   +------------+
+ |                  |<--|                        |---------+    |
+ |                  |<--|                        |<------+ |    |   +--------+
+ +------------------+   +------------------------+       | |    +-->| Slaves |
+   ^  ^    ^    ^          ^                             | |        +--------+
+   |  |    |    |          |                             | V
+ +------+  |  +-----+   +-----+  +---------+   +----------------+   +--------+
+ | CPUs |  |  | GPU |   | DSP |  | Masters |-->|       P NoC    |-->| Slaves |
+ +------+  |  +-----+   +-----+  +---------+   +----------------+   +--------+
+           |
+       +-------+
+       | Modem |
+       +-------+
+
+Terminology
+-----------
+
+Interconnect provider is the software definition of the interconnect hardware.
+The interconnect providers on the above diagram are M NoC, S NoC, C NoC and Mem
+NoC.
+
+Interconnect node is the software definition of the interconnect hardware
+port. Each interconnect provider consists of multiple interconnect nodes,
+which are connected to other SoC components including other interconnect
+providers. The point on the diagram where the CPUs connects to the memory is
+called an interconnect node, which belongs to the Mem NoC interconnect provider.
+
+Interconnect endpoits are the first or the last element of the path. Every
+endpoint is a node, but not every node is an endpoint.
+
+Interconnect path is everything between two endpoints including all the nodes
+that have to be traversed to reach from a source to destination node. It may
+include multiple master-slave pairs across several interconnect providers.
+
+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. An example for a consumer is a a video
+decoder that supports various formats and image sizes.
+
+Interconnect providers
+----------------------
+
+Interconnect provider is an entity that implements methods to initialize and
+configure a interconnect bus hardware. The interconnect provider driver should
+be registered with the interconnect provider core.
+
+The interconnect framework provider API functions are documented in
+.. kernel-doc:: include/linux/interconnect-provider.h
+
+Interconnect consumers
+----------------------
+
+Interconnect consumers are the clients which use the interconnect APIs to
+get paths between endpoints and set their bandwidth/latency/QoS requirements
+for these interconnect paths.
+
+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..94e2a9f01545
--- /dev/null
+++ b/drivers/interconnect/interconnect.c
@@ -0,0 +1,382 @@
+/*
+ * 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 interconnect_node *node = ERR_PTR(-EPROBE_DEFER);
+	struct icp *icp;
+
+	mutex_lock(&interconnect_provider_list_mutex);
+
+	list_for_each_entry(icp, &interconnect_provider_list, icp_list) {
+		struct interconnect_node *n;
+
+		list_for_each_entry(n, &icp->nodes, icn_list) {
+			if (!strcmp(n->dev_id, dev_id) && n->con_id == con_id) {
+				node = n;
+				goto out;
+			}
+		}
+	}
+
+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);
+
+		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 interconnect_node *node = NULL;
+	struct list_head traverse_list;
+	struct list_head edge_list;
+	struct list_head tmp_list;
+	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 void interconnect_aggregate_icn(struct interconnect_node *node)
+{
+	struct interconnect_req *r;
+	u32 avg_bw = 0;
+	u32 peak_bw = 0;
+
+	hlist_for_each_entry(r, &node->req_list, req_node) {
+		/* sum(averages) and max(peaks) */
+		avg_bw += r->avg_bw;
+		peak_bw = max(peak_bw, r->peak_bw);
+	}
+
+	node->creq.avg_bw = avg_bw;
+	node->creq.peak_bw = peak_bw;
+}
+
+static void interconnect_aggregate_icp(struct icp *icp)
+{
+	struct interconnect_node *n;
+	u32 avg_bw = 0;
+	u32 peak_bw = 0;
+
+	/* aggregate for the interconnect provider */
+	list_for_each_entry(n, &icp->nodes, icn_list) {
+		/* sum the average and max the peak */
+		avg_bw += n->creq.avg_bw;
+		peak_bw = max(peak_bw, n->creq.peak_bw);
+	}
+
+	/* save the aggregated values */
+	icp->creq.avg_bw = avg_bw;
+	icp->creq.peak_bw = 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)
+{
+	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;
+
+		/*
+		 * Both endpoints should be valid and master-slave pairs of
+		 * the same interconnect provider that will be configured.
+		 */
+		if (!next || !prev)
+			continue;
+		if (next->icp != prev->icp)
+			continue;
+
+		mutex_lock(&next->icp->lock);
+
+		/* update the consumer request for this path */
+		path->reqs[i].avg_bw = creq->avg_bw;
+		path->reqs[i].peak_bw = creq->peak_bw;
+
+		/* aggregate all requests */
+		interconnect_aggregate_icn(next);
+		interconnect_aggregate_icp(next->icp);
+
+		if (next->icp->ops->set) {
+			/* 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 (!path || WARN_ON_ONCE(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);
+
+		mutex_lock(&node->icp->lock);
+		node->icp->users--;
+		mutex_unlock(&node->icp->lock);
+	}
+
+	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)
+{
+	if (!icp)
+		return -EINVAL;
+
+	if (!icp->ops->set) {
+		dev_err(icp->dev, "%s: .set is not implemented\n", __func__);
+		return -EINVAL;
+	}
+
+	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..6e71bf7a63c0
--- /dev/null
+++ b/include/linux/interconnect-consumer.h
@@ -0,0 +1,73 @@
+/*
+ * 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,
+			    struct interconnect_creq *creq);
+{
+	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..6cf6f6a79846
--- /dev/null
+++ b/include/linux/interconnect-provider.h
@@ -0,0 +1,119 @@
+/*
+ * 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
+ *
+ * @set: set constraints on interconnect
+ */
+struct icp_ops {
+	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
+ * @creq: aggregated values of all 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;
+	struct interconnect_creq creq;
+
+	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 */

[RFC v3 2/3] interconnect: Add basic event tracing

[Georgi Djakov]

Add basic tracepoints in interconnect_set() so we can trace the
performance and the operations which configure the hardware.

Signed-off-by: Georgi Djakov <georgi.djakov@linaro.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Ingo Molnar <mingo@redhat.com>
---
 drivers/interconnect/interconnect.c |  7 ++++++
 include/trace/events/interconnect.h | 45 +++++++++++++++++++++++++++++++++++++
 2 files changed, 52 insertions(+)
 create mode 100644 include/trace/events/interconnect.h

diff --git a/drivers/interconnect/interconnect.c b/drivers/interconnect/interconnect.c
index 94e2a9f01545..4a016f3bedc3 100644
--- a/drivers/interconnect/interconnect.c
+++ b/drivers/interconnect/interconnect.c
@@ -33,6 +33,9 @@ struct interconnect_path {
 	struct interconnect_req reqs[0];
 };
 
+#define CREATE_TRACE_POINTS
+#include <trace/events/interconnect.h>
+
 static struct interconnect_node *node_find(const char *dev_id, int con_id)
 {
 	struct interconnect_node *node = ERR_PTR(-EPROBE_DEFER);
@@ -209,6 +212,8 @@ int interconnect_set(struct interconnect_path *path,
 	size_t i;
 	int ret = 0;
 
+	trace_interconnect_set(path);
+
 	for (i = 0; i < path->num_nodes; i++, prev = next) {
 		next = path->reqs[i].node;
 
@@ -242,6 +247,8 @@ int interconnect_set(struct interconnect_path *path,
 	}
 
 out:
+	trace_interconnect_set_complete(path);
+
 	return ret;
 }
 
diff --git a/include/trace/events/interconnect.h b/include/trace/events/interconnect.h
new file mode 100644
index 000000000000..c4a72163873c
--- /dev/null
+++ b/include/trace/events/interconnect.h
@@ -0,0 +1,45 @@
+#undef TRACE_SYSTEM
+#define TRACE_SYSTEM interconnect
+
+#if !defined(_TRACE_INTERCONNECT_H) || defined(TRACE_HEADER_MULTI_READ)
+#define _TRACE_INTERCONNECT_H
+
+#include <linux/tracepoint.h>
+
+struct interconnect_path;
+
+DECLARE_EVENT_CLASS(interconnect_path,
+
+	TP_PROTO(struct interconnect_path *path),
+
+	TP_ARGS(path),
+
+	TP_STRUCT__entry(
+		__field(struct interconnect_path *, path)
+	),
+
+	TP_fast_assign(
+		__entry->path = path;
+	),
+
+	TP_printk("INTERCONNECT: %p", __entry->path)
+);
+
+DEFINE_EVENT(interconnect_path, interconnect_set,
+
+	TP_PROTO(struct interconnect_path *path),
+
+	TP_ARGS(path)
+);
+
+DEFINE_EVENT(interconnect_path, interconnect_set_complete,
+
+	TP_PROTO(struct interconnect_path *path),
+
+	TP_ARGS(path)
+);
+
+#endif /* _TRACE_INTERCONNECT_H */
+
+/* This part must be outside protection */
+#include <trace/define_trace.h>

[PATCH v3 3/3] interconnect: Add Qualcomm msm8916 interconnect provider driver

[Georgi Djakov]

Add driver for the Qualcomm interconnect buses found in msm8916 based
platforms. This patch contains only a partial 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                |  11 +
 drivers/interconnect/qcom/Makefile               |   1 +
 drivers/interconnect/qcom/interconnect_msm8916.c | 375 +++++++++++++++++++++++
 include/linux/interconnect/qcom-msm8916.h        |  92 ++++++
 6 files changed, 485 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/linux/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..86465dc37bd4
--- /dev/null
+++ b/drivers/interconnect/qcom/Kconfig
@@ -0,0 +1,11 @@
+config INTERCONNECT_QCOM
+	bool "Qualcomm Network-on-Chip interconnect drivers"
+	depends on INTERCONNECT
+	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..0831080e1100
--- /dev/null
+++ b/drivers/interconnect/qcom/Makefile
@@ -0,0 +1 @@
+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..9b001e100974
--- /dev/null
+++ b/drivers/interconnect/qcom/interconnect_msm8916.c
@@ -0,0 +1,375 @@
+/*
+ * 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 <linux/clk.h>
+#include <linux/device.h>
+#include <linux/io.h>
+#include <linux/interconnect-provider.h>
+#include <linux/interconnect/qcom-msm8916.h>
+#include <linux/module.h>
+#include <linux/of_device.h>
+#include <linux/of_platform.h>
+#include <linux/platform_device.h>
+#include <linux/slab.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,
+};
+
+struct qcom_interconnect_provider {
+	struct icp		icp;
+	void __iomem		*base;
+	struct clk		*bus_clk;
+	struct clk		*bus_a_clk;
+	u32			base_offset;
+	u32			qos_offset;
+	enum qcom_bus_type	type;
+};
+
+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);
+
+	/* populate default values */
+	if (!qn->buswidth)
+		qn->buswidth = 8;
+
+	/* TODO: init qos and priority */
+
+	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 = {
+	.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;
+	u32 type, base_offset, qos_offset;
+
+	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);
+
+	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 the node to interconnect provider */
+		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,msm8916-pnoc", .data = &msm8916_pnoc },
+	{ .compatible = "qcom,msm8916-snoc", .data = &msm8916_snoc },
+	{ .compatible = "qcom,msm8916-bimc", .data = &msm8916_bimc },
+	{ },
+};
+MODULE_DEVICE_TABLE(of, qnoc_of_match);
+
+static struct platform_driver qnoc_driver = {
+	.probe = qnoc_probe,
+	.driver = {
+		.name = "qnoc-msm8916",
+		.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/linux/interconnect/qcom-msm8916.h b/include/linux/interconnect/qcom-msm8916.h
new file mode 100644
index 000000000000..355582a09bea
--- /dev/null
+++ b/include/linux/interconnect/qcom-msm8916.h
@@ -0,0 +1,92 @@
+#ifndef __LINUX_INTERCONNECT_QCOM_NOC_H
+#define __LINUX_INTERCONNECT_QCOM_NOC_H
+
+#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
+
+#endif

Re: [RFC v3 2/3] interconnect: Add basic event tracing

[Steven Rostedt]

On Fri,  8 Sep 2017 20:18:29 +0300
Georgi Djakov <georgi.djakov@linaro.org> wrote:

> diff --git a/include/trace/events/interconnect.h b/include/trace/events/interconnect.h
> new file mode 100644
> index 000000000000..c4a72163873c
> --- /dev/null
> +++ b/include/trace/events/interconnect.h
> @@ -0,0 +1,45 @@
> +#undef TRACE_SYSTEM
> +#define TRACE_SYSTEM interconnect
> +
> +#if !defined(_TRACE_INTERCONNECT_H) || defined(TRACE_HEADER_MULTI_READ)
> +#define _TRACE_INTERCONNECT_H
> +
> +#include <linux/tracepoint.h>
> +
> +struct interconnect_path;
> +
> +DECLARE_EVENT_CLASS(interconnect_path,
> +
> +	TP_PROTO(struct interconnect_path *path),
> +
> +	TP_ARGS(path),
> +
> +	TP_STRUCT__entry(
> +		__field(struct interconnect_path *, path)
> +	),
> +
> +	TP_fast_assign(
> +		__entry->path = path;
> +	),
> +
> +	TP_printk("INTERCONNECT: %p", __entry->path)

You're passing in an interconnect_path and only recording the pointer
to it? Wouldn't it be useful to record other aspects? Like the number
of nodes, the avg and peak bw of each node?

-- Steve

> +);
> +
> +DEFINE_EVENT(interconnect_path, interconnect_set,
> +
> +	TP_PROTO(struct interconnect_path *path),
> +
> +	TP_ARGS(path)
> +);
> +
> +DEFINE_EVENT(interconnect_path, interconnect_set_complete,
> +
> +	TP_PROTO(struct interconnect_path *path),
> +
> +	TP_ARGS(path)
> +);
> +
> +#endif /* _TRACE_INTERCONNECT_H */
> +
> +/* This part must be outside protection */
> +#include <trace/define_trace.h>

Re: [RFC v3 2/3] interconnect: Add basic event tracing

[Georgi Djakov]

On 8.09.17 г. 21:13, Steven Rostedt wrote:
> On Fri,  8 Sep 2017 20:18:29 +0300
> Georgi Djakov <georgi.djakov@linaro.org> wrote:
> 
>> diff --git a/include/trace/events/interconnect.h b/include/trace/events/interconnect.h
>> new file mode 100644
>> index 000000000000..c4a72163873c
>> --- /dev/null
>> +++ b/include/trace/events/interconnect.h
>> @@ -0,0 +1,45 @@
>> +#undef TRACE_SYSTEM
>> +#define TRACE_SYSTEM interconnect
>> +
>> +#if !defined(_TRACE_INTERCONNECT_H) || defined(TRACE_HEADER_MULTI_READ)
>> +#define _TRACE_INTERCONNECT_H
>> +
>> +#include <linux/tracepoint.h>
>> +
>> +struct interconnect_path;
>> +
>> +DECLARE_EVENT_CLASS(interconnect_path,
>> +
>> +	TP_PROTO(struct interconnect_path *path),
>> +
>> +	TP_ARGS(path),
>> +
>> +	TP_STRUCT__entry(
>> +		__field(struct interconnect_path *, path)
>> +	),
>> +
>> +	TP_fast_assign(
>> +		__entry->path = path;
>> +	),
>> +
>> +	TP_printk("INTERCONNECT: %p", __entry->path)
> 
> You're passing in an interconnect_path and only recording the pointer
> to it? Wouldn't it be useful to record other aspects? Like the number
> of nodes, the avg and peak bw of each node?
> 

My goal was to get just the path with some timestamps, but your suggestion
sounds good. Will do it. Thanks!

Re: [PATCH v3 1/3] interconnect: Add generic on-chip interconnect API

[Georgi Djakov]

Hi,

On 09/08/2017 08:18 PM, Georgi Djakov wrote:
> This patch introduce a new API to get requirements 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 buses and the consumers could be various drivers.
> The consumers request interconnect resources (path) between endpoints and
> set the desired constraints on this data flow path. The providers 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 |  93 +++++++
>  drivers/Kconfig                             |   2 +
>  drivers/Makefile                            |   1 +
>  drivers/interconnect/Kconfig                |  10 +
>  drivers/interconnect/Makefile               |   1 +
>  drivers/interconnect/interconnect.c         | 382 ++++++++++++++++++++++++++++
>  include/linux/interconnect-consumer.h       |  73 ++++++
>  include/linux/interconnect-provider.h       | 119 +++++++++
>  8 files changed, 681 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

Any comments on this patch?

I am planning to change the prefix that is used for naming for example
the functions from "interconnect_" to something shorter like icbus_.

Thanks,
Georgi

Re: [PATCH v3 1/3] interconnect: Add generic on-chip interconnect API

[Bjorn Andersson]

On Fri 20 Oct 07:43 PDT 2017, Georgi Djakov wrote:

> Hi,
> 
> On 09/08/2017 08:18 PM, Georgi Djakov wrote:
> > This patch introduce a new API to get requirements 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 buses and the consumers could be various drivers.
> > The consumers request interconnect resources (path) between endpoints and
> > set the desired constraints on this data flow path. The providers 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 |  93 +++++++
> >  drivers/Kconfig                             |   2 +
> >  drivers/Makefile                            |   1 +
> >  drivers/interconnect/Kconfig                |  10 +
> >  drivers/interconnect/Makefile               |   1 +
> >  drivers/interconnect/interconnect.c         | 382 ++++++++++++++++++++++++++++
> >  include/linux/interconnect-consumer.h       |  73 ++++++
> >  include/linux/interconnect-provider.h       | 119 +++++++++
> >  8 files changed, 681 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
> 
> Any comments on this patch?
> 

Sorry, I still haven't found the time to do a proper review of this yet.

> I am planning to change the prefix that is used for naming for example
> the functions from "interconnect_" to something shorter like icbus_.
> 

This isn't implementing a bus; if you feel that just ic_ is too short I
would suggest naming things inter_. (But keep the full name in the file
names)

Regards,
Bjorn

Re: [PATCH v3 1/3] interconnect: Add generic on-chip interconnect API

[Michael Turquette]

Hi all,

On Fri, Oct 20, 2017 at 3:34 PM, Bjorn Andersson
<bjorn.andersson@linaro.org> wrote:
> On Fri 20 Oct 07:43 PDT 2017, Georgi Djakov wrote:
>
>> Hi,
>>
>> On 09/08/2017 08:18 PM, Georgi Djakov wrote:
>> > This patch introduce a new API to get requirements 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 buses and the consumers could be various drivers.
>> > The consumers request interconnect resources (path) between endpoints and
>> > set the desired constraints on this data flow path. The providers 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 |  93 +++++++
>> >  drivers/Kconfig                             |   2 +
>> >  drivers/Makefile                            |   1 +
>> >  drivers/interconnect/Kconfig                |  10 +
>> >  drivers/interconnect/Makefile               |   1 +
>> >  drivers/interconnect/interconnect.c         | 382 ++++++++++++++++++++++++++++
>> >  include/linux/interconnect-consumer.h       |  73 ++++++
>> >  include/linux/interconnect-provider.h       | 119 +++++++++
>> >  8 files changed, 681 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
>>
>> Any comments on this patch?
>>
>
> Sorry, I still haven't found the time to do a proper review of this yet.

Same.

>
>> I am planning to change the prefix that is used for naming for example
>> the functions from "interconnect_" to something shorter like icbus_.
>>
>
> This isn't implementing a bus; if you feel that just ic_ is too short I
> would suggest naming things inter_. (But keep the full name in the file
> names)

Not trying to bikeshed too much, but how about icc_ for "interconnect
controller"? No idea if that is a hash collision with other in-kernel
apis.

Just "ic_" looks to me like "integrated circuit".

Regards,
Mike

>
> Regards,
> Bjorn

Re: [PATCH v3 1/3] interconnect: Add generic on-chip interconnect API

[Amit Kucheria]

On Fri, Sep 8, 2017 at 10:48 PM, Georgi Djakov <georgi.djakov@linaro.org> wrote:
> This patch introduce a new API to get requirements 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 buses and the consumers could be various drivers.
> The consumers request interconnect resources (path) between endpoints and
> set the desired constraints on this data flow path. The providers 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 |  93 +++++++
>  drivers/Kconfig                             |   2 +
>  drivers/Makefile                            |   1 +
>  drivers/interconnect/Kconfig                |  10 +
>  drivers/interconnect/Makefile               |   1 +
>  drivers/interconnect/interconnect.c         | 382 ++++++++++++++++++++++++++++
>  include/linux/interconnect-consumer.h       |  73 ++++++
>  include/linux/interconnect-provider.h       | 119 +++++++++
>  8 files changed, 681 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..b057e9c12d70
> --- /dev/null
> +++ b/Documentation/interconnect/interconnect.rst
> @@ -0,0 +1,93 @@
> +=====================================
> +GENERIC SYSTEM INTERCONNECT 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 bus 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 buses 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 interconnect bus topology.
> +
> +::
> +
> + +----------------+    +----------------+
> + | HW Accelerator |--->|      M NoC     |<---------------+
> + +----------------+    +----------------+                |
> +                         |      |                    +------------+
> +  +-----+  +-------------+      V       +------+     |            |
> +  | DDR |  |                +--------+  | PCIe |     |            |
> +  +-----+  |                | Slaves |  +------+     |            |
> +    ^ ^    |                +--------+     |         |   C NoC    |
> +    | |    V                               V         |            |
> + +------------------+   +------------------------+   |            |   +-----+
> + |                  |-->|                        |-->|            |-->| CPU |
> + |                  |-->|                        |<--|            |   +-----+
> + |     Mem NoC      |   |         S NoC          |   +------------+
> + |                  |<--|                        |---------+    |
> + |                  |<--|                        |<------+ |    |   +--------+
> + +------------------+   +------------------------+       | |    +-->| Slaves |
> +   ^  ^    ^    ^          ^                             | |        +--------+
> +   |  |    |    |          |                             | V
> + +------+  |  +-----+   +-----+  +---------+   +----------------+   +--------+
> + | CPUs |  |  | GPU |   | DSP |  | Masters |-->|       P NoC    |-->| Slaves |
> + +------+  |  +-----+   +-----+  +---------+   +----------------+   +--------+
> +           |
> +       +-------+
> +       | Modem |
> +       +-------+
> +
> +Terminology
> +-----------
> +
> +Interconnect provider is the software definition of the interconnect hardware.
> +The interconnect providers on the above diagram are M NoC, S NoC, C NoC and Mem
> +NoC.
> +
> +Interconnect node is the software definition of the interconnect hardware
> +port. Each interconnect provider consists of multiple interconnect nodes,
> +which are connected to other SoC components including other interconnect
> +providers. The point on the diagram where the CPUs connects to the memory is
> +called an interconnect node, which belongs to the Mem NoC interconnect provider.
> +
> +Interconnect endpoits are the first or the last element of the path. Every

s/endpoits/endpoints

> +endpoint is a node, but not every node is an endpoint.
> +
> +Interconnect path is everything between two endpoints including all the nodes
> +that have to be traversed to reach from a source to destination node. It may
> +include multiple master-slave pairs across several interconnect providers.
> +
> +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. An example for a consumer is a a video

typo: is a video

> +decoder that supports various formats and image sizes.
> +
> +Interconnect providers
> +----------------------
> +
> +Interconnect provider is an entity that implements methods to initialize and
> +configure a interconnect bus hardware. The interconnect provider driver should
> +be registered with the interconnect provider core.
> +
> +The interconnect framework provider API functions are documented in
> +.. kernel-doc:: include/linux/interconnect-provider.h
> +
> +Interconnect consumers
> +----------------------
> +
> +Interconnect consumers are the clients which use the interconnect APIs to
> +get paths between endpoints and set their bandwidth/latency/QoS requirements
> +for these interconnect paths.
> +
> +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..94e2a9f01545
> --- /dev/null
> +++ b/drivers/interconnect/interconnect.c
> @@ -0,0 +1,382 @@
> +/*
> + * 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];
> +};

<snip>

> +/**
> + * 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;
> +
> +               /*
> +                * Both endpoints should be valid and master-slave pairs of

Losing the 'and' improves readability.

> +                * the same interconnect provider that will be configured.
> +                */
> +               if (!next || !prev)
> +                       continue;
> +               if (next->icp != prev->icp)
> +                       continue;
> +
> +               mutex_lock(&next->icp->lock);
> +
> +               /* update the consumer request for this path */
> +               path->reqs[i].avg_bw = creq->avg_bw;
> +               path->reqs[i].peak_bw = creq->peak_bw;
> +
> +               /* aggregate all requests */
> +               interconnect_aggregate_icn(next);
> +               interconnect_aggregate_icp(next->icp);
> +
> +               if (next->icp->ops->set) {
> +                       /* commit the aggregated constraints */
> +                       ret = next->icp->ops->set(prev, next, &next->icp->creq);
> +               }

A comment here on how the contraints are propagated along the path
would be good. At the moment, this seems to go to each provider along
the path, take the provider lock and set the new constraints, then
move on to the next provider. Is there any need to make the changes
along the entire path "atomic"?

I'm trying to understand what happens in the case where a new request
comes along while the previous path is still be traversed.

> +               mutex_unlock(&next->icp->lock);
> +               if (ret)
> +                       goto out;
> +       }
> +
> +out:
> +       return ret;
> +}
> +
> +/**
> + * interconnect_get() - return a handle for path between two endpoints

This is not used currently by the msm8916 platform driver? Is this
expected to be called by leaf device drivers or by higher layer bus
drivers? I suspect a mix of the two, but an example would be nice.

> + * @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 (!path || WARN_ON_ONCE(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);
> +
> +               mutex_lock(&node->icp->lock);
> +               node->icp->users--;
> +               mutex_unlock(&node->icp->lock);
> +       }
> +
> +       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)
> +{
> +       if (!icp)
> +               return -EINVAL;
> +
> +       if (!icp->ops->set) {
> +               dev_err(icp->dev, "%s: .set is not implemented\n", __func__);
> +               return -EINVAL;
> +       }
> +
> +       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..6e71bf7a63c0
> --- /dev/null
> +++ b/include/linux/interconnect-consumer.h
> @@ -0,0 +1,73 @@
> +/*
> + * 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,
> +                           struct interconnect_creq *creq);
> +{
> +       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..6cf6f6a79846
> --- /dev/null
> +++ b/include/linux/interconnect-provider.h
> @@ -0,0 +1,119 @@
> +/*
> + * 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
> + *
> + * @set: set constraints on interconnect
> + */
> +struct icp_ops {
> +       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;
> +};

Use interconnect_provider here instead of icp for the sake of
consistency. Same for icp_ops. Or replace everything with any of the
other suggested alternatives. My suggestion to the name pool is 'xcon'
where x == inter.

> +/**
> + * 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
> + * @creq: aggregated values of all 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;
> +       struct interconnect_creq creq;
> +
> +       const char              *dev_id;
> +       int                     con_id;
> +};

Re: [PATCH v3 3/3] interconnect: Add Qualcomm msm8916 interconnect provider driver

[Amit Kucheria]

On Fri, Sep 8, 2017 at 10:48 PM, Georgi Djakov <georgi.djakov@linaro.org> wrote:
> Add driver for the Qualcomm interconnect buses found in msm8916 based
> platforms. This patch contains only a partial 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                |  11 +
>  drivers/interconnect/qcom/Makefile               |   1 +
>  drivers/interconnect/qcom/interconnect_msm8916.c | 375 +++++++++++++++++++++++
>  include/linux/interconnect/qcom-msm8916.h        |  92 ++++++
>  6 files changed, 485 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/linux/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..86465dc37bd4
> --- /dev/null
> +++ b/drivers/interconnect/qcom/Kconfig
> @@ -0,0 +1,11 @@
> +config INTERCONNECT_QCOM
> +       bool "Qualcomm Network-on-Chip interconnect drivers"
> +       depends on INTERCONNECT
> +       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..0831080e1100
> --- /dev/null
> +++ b/drivers/interconnect/qcom/Makefile
> @@ -0,0 +1 @@
> +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..9b001e100974
> --- /dev/null
> +++ b/drivers/interconnect/qcom/interconnect_msm8916.c
> @@ -0,0 +1,375 @@
> +/*
> + * 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 <linux/clk.h>
> +#include <linux/device.h>
> +#include <linux/io.h>
> +#include <linux/interconnect-provider.h>
> +#include <linux/interconnect/qcom-msm8916.h>
> +#include <linux/module.h>
> +#include <linux/of_device.h>
> +#include <linux/of_platform.h>
> +#include <linux/platform_device.h>
> +#include <linux/slab.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,
> +};
> +
> +struct qcom_interconnect_provider {
> +       struct icp              icp;
> +       void __iomem            *base;
> +       struct clk              *bus_clk;
> +       struct clk              *bus_a_clk;
> +       u32                     base_offset;
> +       u32                     qos_offset;
> +       enum qcom_bus_type      type;
> +};
> +
> +struct qcom_interconnect_node {
> +       struct interconnect_node node;
> +       unsigned char *name;
> +       struct interconnect_node *links[8];

Magic number 8. Replace with 8916_MAX_LINKS or something.

> +       u16 id;
> +       u16 num_links;
> +       u16 port;
> +       u16 buswidth;

Comment on what a buswidth is just to be clear

> +       u64 rate;

Comment on units

> +};
> +
> +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;

IMO, saving an 'a' and 'e' is not worth it for the sake of
readability. Just use 'slave' and 'master' in the names.

> +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

Please get rid if these.

> +       .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,
> +};


Suggest replacing this list of definitions with a macro such as:

#define DEFINE_XCON_NODE(_name, _id, numlinks, buswidth, ...) \
             static struct qcom_interconnect_node _name;                       \
             static struct qcom_interconnect_node _name = {                  \
                   .id = _id,
                                 \
                   .name = _name,
                        \
                   .buswidth = buswidth,
                      \
                   .num_links = numlinks,
                    \
                   .links = { __VA_ARGS__ },
                \
            };


This will reduce these definitions to a series of definitions as
follows that improves readability.

DEFINE_XCON_NODE(snoc_int_0, 10004, 1, 8, &snoc_pnoc_mas.node)
DEFINE_XCON_NODE(snoc_int_1, 10005, 3, 8, &snoc_apss.node,
&slv_cats_0.node, &slv_cats_1.node)
DEFINE_XCON_NODE(snoc_int_bimc, 10006, 1, 8, &snoc_bimc_0_mas.node)

If fact you could take it one step further and move the definitions
under the provider definition below directly.

> +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,
> +};

There are big holes in this node array definition because the index
values are not contiguous. Are you planning fill these in later for
each of the providers?

> +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);
> +
> +       /* populate default values */
> +       if (!qn->buswidth)
> +               qn->buswidth = 8;
> +
> +       /* TODO: init qos and priority */
> +
> +       return 0;

Re: [PATCH v3 1/3] interconnect: Add generic on-chip interconnect API

[Georgi Djakov]

Hi Amit,

On 11/02/2017 09:28 AM, Amit Kucheria wrote:
[..>> +Interconnect node is the software definition of the interconnect
hardware
>> +port. Each interconnect provider consists of multiple interconnect nodes,
>> +which are connected to other SoC components including other interconnect
>> +providers. The point on the diagram where the CPUs connects to the memory is
>> +called an interconnect node, which belongs to the Mem NoC interconnect provider.
>> +
>> +Interconnect endpoits are the first or the last element of the path. Every
> 
> s/endpoits/endpoints
> 

Ok!

>> +endpoint is a node, but not every node is an endpoint.
>> +
>> +Interconnect path is everything between two endpoints including all the nodes
>> +that have to be traversed to reach from a source to destination node. It may
>> +include multiple master-slave pairs across several interconnect providers.
>> +
>> +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. An example for a consumer is a a video
> 
> typo: is a video>

Ok!

[..]
>> +/**
>> + * 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;
>> +
>> +               /*
>> +                * Both endpoints should be valid and master-slave pairs of
> 
> Losing the 'and' improves readability.
> 

Ok!

>> +                * the same interconnect provider that will be configured.
>> +                */
>> +               if (!next || !prev)
>> +                       continue;
>> +               if (next->icp != prev->icp)
>> +                       continue;
>> +
>> +               mutex_lock(&next->icp->lock);
>> +
>> +               /* update the consumer request for this path */
>> +               path->reqs[i].avg_bw = creq->avg_bw;
>> +               path->reqs[i].peak_bw = creq->peak_bw;
>> +
>> +               /* aggregate all requests */
>> +               interconnect_aggregate_icn(next);
>> +               interconnect_aggregate_icp(next->icp);
>> +
>> +               if (next->icp->ops->set) {
>> +                       /* commit the aggregated constraints */
>> +                       ret = next->icp->ops->set(prev, next, &next->icp->creq);
>> +               }
> 
> A comment here on how the contraints are propagated along the path
> would be good. At the moment, this seems to go to each provider along
> the path, take the provider lock and set the new constraints, then
> move on to the next provider. Is there any need to make the changes
> along the entire path "atomic"?

Yes, the above is correct. There is no such need at least for the
hardware i am currently playing with. We can add support for that later
if needed.

> 
> I'm trying to understand what happens in the case where a new request
> comes along while the previous path is still be traversed.

It just gets aggregated and set and this seems to not be an issue as the
paths are valid. Now I am trying to keep it simple and if anything needs
serialization we can add some locking later.

> 
>> +               mutex_unlock(&next->icp->lock);
>> +               if (ret)
>> +                       goto out;
>> +       }
>> +
>> +out:
>> +       return ret;
>> +}
>> +
>> +/**
>> + * interconnect_get() - return a handle for path between two endpoints
> 
> This is not used currently by the msm8916 platform driver? Is this
> expected to be called by leaf device drivers or by higher layer bus
> drivers? I suspect a mix of the two, but an example would be nice.

This is called by a consumer driver to express its for example bandwidth
needs between various endpoints. Will add some examples.

[..]
>> +/**
>> + * 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;
>> +};
> 
> Use interconnect_provider here instead of icp for the sake of
> consistency. Same for icp_ops. Or replace everything with any of the
> other suggested alternatives. My suggestion to the name pool is 'xcon'
> where x == inter.

Yes i am working on better naming, thanks!

BR,
Georgi

Re: [PATCH v3 3/3] interconnect: Add Qualcomm msm8916 interconnect provider driver

[Georgi Djakov]

Hi Amit,

On 11/02/2017 09:28 AM, Amit Kucheria wrote:
> On Fri, Sep 8, 2017 at 10:48 PM, Georgi Djakov <georgi.djakov@linaro.org> wrote:
>> Add driver for the Qualcomm interconnect buses found in msm8916 based
>> platforms. This patch contains only a partial 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                |  11 +
>>  drivers/interconnect/qcom/Makefile               |   1 +
>>  drivers/interconnect/qcom/interconnect_msm8916.c | 375 +++++++++++++++++++++++
>>  include/linux/interconnect/qcom-msm8916.h        |  92 ++++++
>>  6 files changed, 485 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/linux/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..86465dc37bd4
>> --- /dev/null
>> +++ b/drivers/interconnect/qcom/Kconfig
>> @@ -0,0 +1,11 @@
>> +config INTERCONNECT_QCOM
>> +       bool "Qualcomm Network-on-Chip interconnect drivers"
>> +       depends on INTERCONNECT
>> +       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..0831080e1100
>> --- /dev/null
>> +++ b/drivers/interconnect/qcom/Makefile
>> @@ -0,0 +1 @@
>> +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..9b001e100974
>> --- /dev/null
>> +++ b/drivers/interconnect/qcom/interconnect_msm8916.c
>> @@ -0,0 +1,375 @@
>> +/*
>> + * 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 <linux/clk.h>
>> +#include <linux/device.h>
>> +#include <linux/io.h>
>> +#include <linux/interconnect-provider.h>
>> +#include <linux/interconnect/qcom-msm8916.h>
>> +#include <linux/module.h>
>> +#include <linux/of_device.h>
>> +#include <linux/of_platform.h>
>> +#include <linux/platform_device.h>
>> +#include <linux/slab.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,
>> +};
>> +
>> +struct qcom_interconnect_provider {
>> +       struct icp              icp;
>> +       void __iomem            *base;
>> +       struct clk              *bus_clk;
>> +       struct clk              *bus_a_clk;
>> +       u32                     base_offset;
>> +       u32                     qos_offset;
>> +       enum qcom_bus_type      type;
>> +};
>> +
>> +struct qcom_interconnect_node {
>> +       struct interconnect_node node;
>> +       unsigned char *name;
>> +       struct interconnect_node *links[8];
> 
> Magic number 8. Replace with 8916_MAX_LINKS or something.
> 

Ok, sure!

>> +       u16 id;
>> +       u16 num_links;
>> +       u16 port;
>> +       u16 buswidth;
> 
> Comment on what a buswidth is just to be clear
> 

Ok!

>> +       u64 rate;
> 
> Comment on units

Ok!

> 
>> +};
>> +
>> +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;
> 
> IMO, saving an 'a' and 'e' is not worth it for the sake of
> readability. Just use 'slave' and 'master' in the names.
> 

Currently i prefer to keep it this way. Maybe i can put a comment
somewhere.

>> +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
> 
> Please get rid if these.
> 

I have included only a small part of the topology for this SoC for
simplicity. Will remove them.

>> +       .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,
>> +};
> 
> 
> Suggest replacing this list of definitions with a macro such as:
> 
> #define DEFINE_XCON_NODE(_name, _id, numlinks, buswidth, ...) \
>              static struct qcom_interconnect_node _name;                       \
>              static struct qcom_interconnect_node _name = {                  \
>                    .id = _id,
>                                  \
>                    .name = _name,
>                         \
>                    .buswidth = buswidth,
>                       \
>                    .num_links = numlinks,
>                     \
>                    .links = { __VA_ARGS__ },
>                 \
>             };
> 
> 
> This will reduce these definitions to a series of definitions as
> follows that improves readability.
> 
> DEFINE_XCON_NODE(snoc_int_0, 10004, 1, 8, &snoc_pnoc_mas.node)
> DEFINE_XCON_NODE(snoc_int_1, 10005, 3, 8, &snoc_apss.node,
> &slv_cats_0.node, &slv_cats_1.node)
> DEFINE_XCON_NODE(snoc_int_bimc, 10006, 1, 8, &snoc_bimc_0_mas.node)
> 
> If fact you could take it one step further and move the definitions
> under the provider definition below directly.
> 

Will do it. Thanks!

[..]

>> +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,
>> +};
> 
> There are big holes in this node array definition because the index
> values are not contiguous. Are you planning fill these in later for
> each of the providers?
> 

Yes, exactly. I trying to keep this patch as small as possible to be
more review friendly. At some time will add the full topology.

Thanks for the comments!

BR,
Georgi

Re: [PATCH v3 1/3] interconnect: Add generic on-chip interconnect API

[Amit Kucheria]

On Fri, Sep 8, 2017 at 10:48 PM, Georgi Djakov <georgi.djakov@linaro.org> wrote:
> This patch introduce a new API to get requirements 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 buses and the consumers could be various drivers.
> The consumers request interconnect resources (path) between endpoints and
> set the desired constraints on this data flow path. The providers 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 |  93 +++++++
>  drivers/Kconfig                             |   2 +
>  drivers/Makefile                            |   1 +
>  drivers/interconnect/Kconfig                |  10 +
>  drivers/interconnect/Makefile               |   1 +
>  drivers/interconnect/interconnect.c         | 382 ++++++++++++++++++++++++++++
>  include/linux/interconnect-consumer.h       |  73 ++++++
>  include/linux/interconnect-provider.h       | 119 +++++++++
>  8 files changed, 681 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
>

<snip>

> diff --git a/include/linux/interconnect-consumer.h b/include/linux/interconnect-consumer.h
> new file mode 100644
> index 000000000000..6e71bf7a63c0
> --- /dev/null
> +++ b/include/linux/interconnect-consumer.h
> @@ -0,0 +1,73 @@
> +/*
> + * 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,
> +                           struct interconnect_creq *creq);

Remove the semi colon

> +{
> +       return -ENOTSUPP

return ERR_PTR(-ENOTSUPP);

> +}
> +

This breaks the build with INTERCONNECT disabled in Kconfig.

Re: [PATCH v3 1/3] interconnect: Add generic on-chip interconnect API

[Georgi Djakov]

Hi Amit,

On 12/08/2017 08:38 PM, Amit Kucheria wrote:
> On Fri, Sep 8, 2017 at 10:48 PM, Georgi Djakov <georgi.djakov@linaro.org> wrote:
>> This patch introduce a new API to get requirements 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 buses and the consumers could be various drivers.
>> The consumers request interconnect resources (path) between endpoints and
>> set the desired constraints on this data flow path. The providers 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>

[..]

>> +inline int interconnect_set(struct interconnect_path *path,
>> +                           struct interconnect_creq *creq);
> 
> Remove the semi colon

Thanks! Fixed.

> 
>> +{
>> +       return -ENOTSUPP
> 
> return ERR_PTR(-ENOTSUPP);

I do not agree here. It should be left as is, because the function
returns int.

> 
>> +}
>> +
> 
> This breaks the build with INTERCONNECT disabled in Kconfig.

Ok, i have fixed this as well.

Thanks,
Georgi

Re: [PATCH v3 1/3] interconnect: Add generic on-chip interconnect API

[Rob Clark]

On Fri, Sep 8, 2017 at 1:18 PM, Georgi Djakov <georgi.djakov@linaro.org> wrote:
> This patch introduce a new API to get requirements 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 buses and the consumers could be various drivers.
> The consumers request interconnect resources (path) between endpoints and
> set the desired constraints on this data flow path. The providers 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 |  93 +++++++
>  drivers/Kconfig                             |   2 +
>  drivers/Makefile                            |   1 +
>  drivers/interconnect/Kconfig                |  10 +
>  drivers/interconnect/Makefile               |   1 +
>  drivers/interconnect/interconnect.c         | 382 ++++++++++++++++++++++++++++
>  include/linux/interconnect-consumer.h       |  73 ++++++
>  include/linux/interconnect-provider.h       | 119 +++++++++
>  8 files changed, 681 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
>
>

[snip]

> +/**
> + * 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)

drive-by comment... afaict creq could be 'const'

BR,
-R