[PATCH v7 1/8] interconnect: Add generic on-chip interconnect API
From: Randy Dunlap <hidden>
Date: 2018-08-02 00:06:06
Also in:
linux-arm-msm, linux-pm, lkml
On 07/31/2018 09:13 AM, Georgi Djakov wrote:
quoted hunk ↗ jump to hunk
This patch introduces 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 <redacted> --- Documentation/interconnect/interconnect.rst | 96 ++++ drivers/Kconfig | 2 + drivers/Makefile | 1 + drivers/interconnect/Kconfig | 10 + drivers/interconnect/Makefile | 2 + drivers/interconnect/core.c | 569 ++++++++++++++++++++ include/linux/interconnect-provider.h | 125 +++++ include/linux/interconnect.h | 42 ++ 8 files changed, 847 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/core.c create mode 100644 include/linux/interconnect-provider.h create mode 100644 include/linux/interconnect.hdiff --git a/Documentation/interconnect/interconnect.rst b/Documentation/interconnect/interconnect.rst new file mode 100644 index 000000000000..e628881ee218 --- /dev/null +++ b/Documentation/interconnect/interconnect.rst@@ -0,0 +1,96 @@ +.. SPDX-License-Identifier: GPL-2.0 + +===================================== +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,
I would say: on an SoC. Do you pronounce that as "sock" or the letters S.O.C.?
+latency and priority between multiple interconnected devices or functional +blocks. 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
bus is hardware
+set on a data path according to the requests received from various drivers. +An example of interconnect buses are the interconnects between various +components or functional blocks in chipsets. There can be multiple interconnects +on a SoC that can be multi-tiered.
an SoC
+ +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, P 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 connect to the memory is +called an interconnect node, which belongs to the Mem NoC interconnect provider. + +Interconnect endpoints 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 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 drivers should
configure interconnect bus hardware. (i.e., drop the "a")
+be registered with the interconnect provider core. + +The interconnect framework provider API functions are documented in +.. kernel-doc:: include/linux/interconnect-provider.h
What do you want that to do? and does that happen? The .. kernel-doc:: line won't be printed. It will just be expanded to the contents of that header file, so the preceding sentence fragment will look/sound odd.
+ +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.h
same as above. -- ~Randy