Messages in this thread Patch in this message | ![/](/images/icornerl.gif) | | From | Vincent Guittot <> | Date | Wed, 31 May 2017 18:02:04 +0200 | Subject | Re: [RFC v1 1/3] interconnect: Add generic interconnect controller API |
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On 15 May 2017 at 17:35, Georgi Djakov <georgi.djakov@linaro.org> wrote: > This patch introduce a new API to get the requirement and configure the > interconnect buses across the entire chipset to fit with the current demand. > > The API is using a consumer/provider-based model, where the providers are > the interconnect controllers and the consumers could be various drivers. > The consumers request interconnect resources (path) to an endpoint and set > the desired constraints on this data flow path. The provider(s) receive > requests from consumers and aggregate these requests for all master-slave > pairs on that path. Then the providers configure each participating in the > topology node according to the requested data flow path, physical links and > constraints. The topology could be complicated and multi-tiered and is SoC > specific. > > Signed-off-by: Georgi Djakov <georgi.djakov@linaro.org> > --- > Documentation/interconnect/interconnect.txt | 65 ++++++ > drivers/Kconfig | 2 + > drivers/Makefile | 1 + > drivers/interconnect/Kconfig | 10 + > drivers/interconnect/Makefile | 1 + > drivers/interconnect/interconnect.c | 317 ++++++++++++++++++++++++++++ > include/linux/interconnect-consumer.h | 84 ++++++++ > include/linux/interconnect-provider.h | 110 ++++++++++ > 8 files changed, 590 insertions(+) > create mode 100644 Documentation/interconnect/interconnect.txt > 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.txt b/Documentation/interconnect/interconnect.txt > new file mode 100644 > index 000000000000..f761a2fb553c > --- /dev/null > +++ b/Documentation/interconnect/interconnect.txt > @@ -0,0 +1,65 @@ > +GENERIC SYSTEM INTERCONNECT CONTROLLER SUBSYSTEM > +=============================================== > + > +1. Introduction > +--------------- > +This framework is designed to provide a standard kernel interface to control > +the settings of the interconnects on a SoC. These settings can be throughput, > +latency and priority between multiple interconnected devices. This can be > +controlled dynamically in order to save power or provide maximum performance. > + > +The interconnect controller is a hardware with configurable parameters, which > +can be set on a data path according to the requests received from various > +drivers. An example of interconnect controllers are the interconnects between > +various components on chipsets. There can be multiple interconnects on a SoC > +that can be multi-tiered. > + > +Below is a simplified diagram of a real-world SoC topology. The interconnect > +providers are the memory front end and the NoCs. > + > ++----------------+ +----------------+ > +| HW Accelerator |--->| M NoC |<---------------+ > ++----------------+ +----------------+ | > + | | +------------+ > + +-------------+ V +------+ | | > + | +--------+ | PCIe | | | > + | | Slaves | +------+ | | > + | +--------+ | | C NoC | > + V V | | > ++------------------+ +------------------------+ | | +-----+ > +| |-->| |-->| |-->| CPU | > +| |-->| |<--| | +-----+ > +| Memory | | S NoC | +------------+ > +| |<--| |---------+ | > +| |<--| |<------+ | | +--------+ > ++------------------+ +------------------------+ | | +-->| Slaves | > + ^ ^ ^ ^ | | +--------+ > + | | | | | V > ++-----+ | +-----+ +-----+ +---------+ +----------------+ +--------+ > +| CPU | | | GPU | | DSP | | Masters |-->| P NoC |-->| Slaves | > ++-----+ | +-----+ +-----+ +---------+ +----------------+ +--------+ > + | > + +-------+ > + | Modem | > + +-------+ > + > +2. Interconnect providers > +------------------------ > +Interconnect provider is an entity that implements methods to initialize and > +configure a interconnect controller hardware. > + > +An interconnect controller should register with the interconnect provider core > +with interconnect_add_provider(). > + > +A previously registered interconnect provider is unregistered with > +interconnect_del_provider(). > + > +3. Interconnect consumers > +------------------------ > +Interconnect consumers are the entities which make use of the data paths exposed > +by the providers. The consumers send requests to providers requesting various > +throughput, latency and priority. Usually the consumers are device drivers, that > +send request based on their needs. > + > +The interconnect framework consumer API functions are documented in > +include/linux/interconnect-consumer.h > diff --git a/drivers/Kconfig b/drivers/Kconfig > index d2ac339de85f..6e4d80e98f5c 100644 > --- a/drivers/Kconfig > +++ b/drivers/Kconfig > @@ -198,4 +198,6 @@ source "drivers/hwtracing/intel_th/Kconfig" > > source "drivers/fpga/Kconfig" > > +source "drivers/interconnect/Kconfig" > + > endmenu > diff --git a/drivers/Makefile b/drivers/Makefile > index 795d0ca714bf..d5b4733f3875 100644 > --- a/drivers/Makefile > +++ b/drivers/Makefile > @@ -172,3 +172,4 @@ obj-$(CONFIG_STM) += hwtracing/stm/ > obj-$(CONFIG_ANDROID) += android/ > obj-$(CONFIG_NVMEM) += nvmem/ > obj-$(CONFIG_FPGA) += fpga/ > +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..633ee157226f > --- /dev/null > +++ b/drivers/interconnect/interconnect.c > @@ -0,0 +1,317 @@ > +/* > + * 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/slab.h> > + > +static DEFINE_MUTEX(interconnect_provider_list_mutex); > +static LIST_HEAD(interconnect_provider_list); > + > +/** > + * struct interconnect_path - interconnect path structure > + * > + * @nodes: array of the nodes in this path > + * @num_nodes: number of hops (nodes) > + */ > +struct interconnect_path { > + struct interconnect_node **nodes; > + size_t num_nodes; > +};
You should better start the struct with size_t num_nodes and put the array of struct interconnect_node **nodes at the end like below struct interconnect_path { size_t num_nodes; struct interconnect_node *nodes[]; };
Then you can do only one allocation for everything kzalloc(sizeof(*path) + number * sizeof(*node), GFP_KERNEL);
> + > +static struct interconnect_node *node_find(const char *dev_id, int con_id) > +{ > + struct icp *icp; > + struct interconnect_node *node = ERR_PTR(-EPROBE_DEFER); > + int match, best = 0; > + > + mutex_lock(&interconnect_provider_list_mutex); > + > + list_for_each_entry(icp, &interconnect_provider_list, icp_list) { > + struct interconnect_node *n; > + > + match = 0; > + > + list_for_each_entry(n, &icp->nodes, icn_list) { > + if (n->dev_id) { > + if (!dev_id || strncmp(n->dev_id, dev_id, > + strlen(dev_id))) > + continue; > + match += 2; > + } > + if (n->con_id) { > + if (!con_id || n->con_id != con_id) > + continue; > + match += 1; > + } > + > + if (match > best) { > + node = n; > + if (match == 3) > + goto out; > + > + best = match; > + } > + } > + } > + > +out: > + mutex_unlock(&interconnect_provider_list_mutex); > + > + return node; > +} > + > +static struct interconnect_path *path_find(struct interconnect_node *src, > + struct interconnect_node *dst) > +{ > + struct list_head edge_list; > + struct list_head traverse_list; > + struct list_head tmp_list; > + struct interconnect_path *path = ERR_PTR(-EPROBE_DEFER); > + struct interconnect_node *node = NULL; > + size_t i, number = 1; > + bool found = false; > + > + INIT_LIST_HEAD(&traverse_list); > + INIT_LIST_HEAD(&edge_list); > + INIT_LIST_HEAD(&tmp_list); > + > + list_add_tail(&src->search_list, &traverse_list); > + > + do { > + list_for_each_entry(node, &traverse_list, search_list) { > + if (node == dst) { > + found = true; > + list_add(&node->search_list, &tmp_list); > + break; > + } > + for (i = 0; i < node->num_links; i++) { > + struct interconnect_node *tmp = node->links[i]; > + > + if (!tmp) { > + WARN_ON(1); > + return ERR_PTR(-ENOENT); > + } > + > + if (tmp->is_traversed) > + continue; > + > + tmp->is_traversed = true; > + tmp->reverse = node; > + list_add_tail(&tmp->search_list, &edge_list); > + } > + } > + if (found) > + break; > + > + list_splice_init(&traverse_list, &tmp_list); > + list_splice_init(&edge_list, &traverse_list); > + > + /* count the number of nodes */ > + number++; > + > + } while (!list_empty(&traverse_list)); > + > + /* reset the traversed state */ > + list_for_each_entry(node, &tmp_list, search_list) { > + node->is_traversed = false; > + } > + > + if (found) { > + path = kzalloc(sizeof(*path), GFP_KERNEL); > + if (!path) > + return ERR_PTR(-ENOMEM); > + > + path->nodes = kcalloc(number, sizeof(*node), GFP_KERNEL); > + if (!path->nodes) { > + kfree(path); > + return ERR_PTR(-ENOMEM); > + } > + > + path->num_nodes = number; > + > + /* start from the destination and go back to source */ > + node = dst; > + > + for (i = 0; i < number; i++) { > + path->nodes[i] = node; > + node = node->reverse; > + } > + } > + > + return path; > +} > + > +int interconnect_set(struct interconnect_path *path, u32 bandwidth) > +{ > + struct interconnect_node *next, *prev = NULL; > + size_t i; > + > + for (i = 0; i < path->num_nodes; i++) { > + struct icn_qos *req; > + u32 agg_bw = 0; > + > + next = path->nodes[i]; > + > + /* aggregate requests */ > + hlist_for_each_entry(req, &next->qos_list, node) { > + if (req->path == path) { > + /* update the bandwidth for the path */ > + req->bandwidth = bandwidth; > + } > + > + agg_bw += req->bandwidth; > + } > + > + if (next->icp->ops->set) > + next->icp->ops->set(prev, next, agg_bw); > + > + prev = next; > + > + /* is this the last node? */ > + if (i == path->num_nodes - 1) { > + if (next->icp->ops->set) > + next->icp->ops->set(next, NULL, agg_bw); > + } > + } > + > + return 0; > +} > + > +struct interconnect_path *interconnect_get(const char *sdev, const int sid, > + const char *ddev, const int did) > +{ > + struct interconnect_node *src, *dst, *node; > + struct interconnect_path *path; > + size_t i; > + > + 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; > + } > + > + for (i = 0; i < path->num_nodes; i++) { > + struct icn_qos *req; > + > + node = path->nodes[i]; > + > + pr_debug("%s: i=%lu node=%p\n", __func__, i, node); > + > + /* > + * Create icn_qos for each separate link between the nodes. > + * They may have different constraints and may belong to > + * different interconnect providers. > + */ > + req = kzalloc(sizeof(*req), GFP_KERNEL); > + if (!req) > + return ERR_PTR(-ENOMEM); > + > + req->path = path; > + req->bandwidth = 0; > + > + hlist_add_head(&req->node, &node->qos_list); > + > + node->icp->users++; > + } > + > + return path; > +} > +EXPORT_SYMBOL_GPL(interconnect_get); > + > +void interconnect_put(struct interconnect_path *path) > +{ > + struct interconnect_node *node; > + struct icn_qos *req; > + struct hlist_node *tmp; > + size_t i; > + int ret; > + > + if (IS_ERR(path)) > + return; > + > + for (i = 0; i < path->num_nodes; i++) { > + node = path->nodes[i]; > + > + hlist_for_each_entry_safe(req, tmp, &node->qos_list, node) { > + if (req->path == path) { > + /* > + * Remove the constraints from the path, > + * update the nodes and free the memory > + */ > + ret = interconnect_set(path, 0); > + if (ret) > + pr_err("%s error %d\n", __func__, ret); > + > + hlist_del(&req->node); > + kfree(req); > + } > + } > + > + node->icp->users--; > + } > + > + kfree(path); > +} > +EXPORT_SYMBOL_GPL(interconnect_put); > + > +int interconnect_add_provider(struct icp *icp) > +{ > + struct interconnect_node *node; > + > + WARN(!icp->ops->set, "%s: .set is not implemented\n", __func__); > + > + mutex_lock(&interconnect_provider_list_mutex); > + list_add(&icp->icp_list, &interconnect_provider_list); > + mutex_unlock(&interconnect_provider_list_mutex); > + > + list_for_each_entry(node, &icp->nodes, icn_list) { > + INIT_HLIST_HEAD(&node->qos_list); > + } > + > + dev_info(icp->dev, "interconnect provider is added to topology\n"); > + > + return 0; > +} > +EXPORT_SYMBOL_GPL(interconnect_add_provider); > + > +int interconnect_del_provider(struct icp *icp) > +{ > + if (icp->users) > + return -EBUSY; > + > + 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..e187efa6c20a > --- /dev/null > +++ b/include/linux/interconnect-consumer.h > @@ -0,0 +1,84 @@ > +/* > + * 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) > + > +/** > + * interconnect_get() - get an interconnect path between two endpoits > + * > + * @sdev: source device identifier > + * @sid: source device port identifier > + * @ddev: destination device identifier > + * @did: destination device port identifier > + * > + * This function will search for a path between the source device (caller) > + * and a destination endpoint. It returns an interconnect_path handle on > + * success. Use interconnect_put() to release constraints when the they > + * are not needed anymore. > + * > + * This function returns a handle on success, or ERR_PTR() otherwise. > + */ > +struct interconnect_path *interconnect_get(const char *sdev, const int sid, > + const char *ddev, const int did); > + > +/** > + * 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); > + > +/** > + * interconnect_set() - set constraints on a path between two endpoints > + * @path: reference to the path returned by interconnect_get() > + * @bandwidth: the requested bandwidth in kpbs between the path endpoints > + * > + * This function sends a request for bandwidth between the two endpoints, > + * (path). It aggragates the requests for constraints and updates each node > + * accordingly. > + * > + * Returns 0 on success, or an approproate error code otherwise. > + */ > +int interconnect_set(struct interconnect_path *path, u32 bandwidth); > + > +#else > + > +inline struct interconnect_path *interconnect_get(const char *sdev, > + const int sid, > + const char *ddev, > + const int did) > +{ > + return ERR_PTR(-ENOSYS); > +} > + > +inline void interconnect_put(struct interconnect_path *path) > +{ > +} > + > +inline int interconnect_set(struct interconnect_path *path, u32 bandwidth) > +{ > + return -ENOSYS; > +} > + > +#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..733d5c3e00b7 > --- /dev/null > +++ b/include/linux/interconnect-provider.h > @@ -0,0 +1,110 @@ > +/* > + * 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, u32 bandwidth); > +}; > + > +/** > + * 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 > + * @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; > + 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 > + * @qos_list: a list of QoS constraints > + * @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 qos_list; > + > + const char *dev_id; > + int con_id; > +}; > + > +/** > + * struct icn_qos - constraints that are attached to each node > + * > + * @node: linked list node > + * @path: the interconnect path which is using this constraint > + * @bandwidth: an integer describing the bandwidth in kbps > + */ > +struct icn_qos { > + struct hlist_node node; > + struct interconnect_path *path; > + u32 bandwidth; > +}; > + > +#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 -ENOSYS; > +} > + > +static inline int interconnect_del_provider(struct icp *icp) > +{ > + return -ENOSYS; > +} > + > +#endif /* CONFIG_INTERCONNECT */ > + > +#endif /* _LINUX_INTERCONNECT_PROVIDER_H */
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