interconnect: Add debugfs test client

It's often useful during test, debug, and development to issue path
votes from shell. Add a debugfs client for this purpose.

Example usage:
cd /sys/kernel/debug/interconnect/test-client/

# Configure node endpoints for the path from CPU to DDR on
# qcom/sm8550.
echo chm_apps > src_node
echo ebi > dst_node

# Get path between src_node and dst_node. This is only
# necessary after updating the node endpoints.
echo 1 > get

# Set desired BW to 1GBps avg and 2GBps peak.
echo 1000000 > avg_bw
echo 2000000 > peak_bw

# Vote for avg_bw and peak_bw on the latest path from "get".
# Voting for multiple paths is possible by repeating this
# process for different nodes endpoints.
echo 1 > commit

Allowing userspace to directly enable and set bus rates can be dangerous
So, following in the footsteps of the regmap [0] and clk [1] frameworks,
keep these userspace controls compile-time disabled without Kconfig
options to enable them. Enabling this will require code changes to
define INTERCONNECT_ALLOW_WRITE_DEBUGFS.

[0] commit 09c6ecd39410 ("regmap: Add support for writing to regmap registers via debugfs")
[1] commit 37215da5553e ("clk: Add support for setting clk_rate via debugfs")

Signed-off-by: Mike Tipton <quic_mdtipton@quicinc.com>
Link: https://lore.kernel.org/r/20230807142914.12480-4-quic_mdtipton@quicinc.com
Signed-off-by: Georgi Djakov <djakov@kernel.org>

interconnect: add clk-based icc provider support

For some devices it is useful to export clocks as interconnect providers,
if the clock corresponds to bus bandwidth.

For example, on MSM8996 the cluster interconnect clock should be scaled
according to the cluster frequencies. Exporting it as an interconnect
allows one to properly describe this as the cluster bandwidth
requirements.

Tested-by: Yassine Oudjana <y.oudjana@protonmail.com>
Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Link: https://lore.kernel.org/r/20230512001334.2983048-3-dmitry.baryshkov@linaro.org
Signed-off-by: Georgi Djakov <djakov@kernel.org>

interconnect: Add generic interconnect driver for Exynos SoCs

This patch adds a generic interconnect driver for Exynos SoCs in order
to provide interconnect functionality for each "samsung,exynos-bus"
compatible device.

The SoC topology is a graph (or more specifically, a tree) and its
edges are described by specifying in the 'interconnects' property
the interconnect consumer path for each interconnect provider DT node.

Each bus is now an interconnect provider and an interconnect node as
well (cf. Documentation/interconnect/interconnect.rst), i.e. every bus
registers itself as a node. Node IDs are not hard coded but rather
assigned dynamically at runtime. This approach allows for using this
driver with various Exynos SoCs.

Frequencies requested via the interconnect API for a given node are
propagated to devfreq using dev_pm_qos_update_request(). Please note
that it is not an error when CONFIG_INTERCONNECT is 'n', in which
case all interconnect API functions are no-op.

The samsung,data-clk-ratio DT property is used to specify the ratio
of the interconect bandwidth to the minimum data clock frequency
for each bus.

Due to unspecified relative probing order, -EPROBE_DEFER may be
propagated to ensure that the parent is probed before its children.

Reviewed-by: Chanwoo Choi <cw00.choi@samsung.com>
Tested-by: Chanwoo Choi <cw00.choi@samsung.com>
Acked-by: Krzysztof Kozlowski <krzk@kernel.org>
Signed-off-by: Artur Świgoń <a.swigon@samsung.com>
Signed-off-by: Sylwester Nawrocki <s.nawrocki@samsung.com>
Link: https://lore.kernel.org/r/20201112140931.31139-3-s.nawrocki@samsung.com
Signed-off-by: Georgi Djakov <georgi.djakov@linaro.org>

interconnect: Add bulk API helpers

There are drivers which just need to get multiple interconnect paths,
request some predefined amounts of bandwidth and then just toggle the
paths between enabled/disabled state.

The aim of this patch is simplify the above and to allow drivers to put
all the path names and bandwidth data into a single static icc_bulk_data
table and call the icc_bulk_* functions on that table in order to scale
all the interconnect paths in parallel.

Suggested-by: Evan Green <evgreen@chromium.org>
Suggested-by: Bjorn Andersson <bjorn.andersson@linaro.org>
Reviewed-by: Bjorn Andersson <bjorn.andersson@linaro.org>
Link: https://lore.kernel.org/r/20200729123439.9961-1-georgi.djakov@linaro.org
Signed-off-by: Georgi Djakov <georgi.djakov@linaro.org>

interconnect: Add imx core driver

This adds support for i.MX SoC family to interconnect framework.

Platform drivers can describe the interconnect graph and several
adjustment knobs where icc node bandwidth is converted to a
DEV_PM_QOS_MIN_FREQUENCY request.

The interconnect provider is probed through the main NOC device and
other adjustable nodes on the same graph are found from a
fsl,scalable-nodes phandle array property.

Signed-off-by: Alexandre Bailon <abailon@baylibre.com>
Signed-off-by: Leonard Crestez <leonard.crestez@nxp.com>
Tested-by: Martin Kepplinger <martin.kepplinger@puri.sm>
Link: https://lore.kernel.org/r/35920e673df6c04cbbb7d877a7d4ba25fd91a784.1586174566.git.leonard.crestez@nxp.com
Signed-off-by: Georgi Djakov <georgi.djakov@linaro.org>

interconnect: Add basic tracepoints

The tracepoints can help with understanding the system behavior of a
given interconnect path when the consumer drivers change their bandwidth
demands. This might be interesting when we want to monitor the requested
interconnect bandwidth for each client driver. The paths may share the
same nodes and this will help to understand "who and when is requesting
what". All this is useful for subsystem drivers developers and may also
provide hints when optimizing the power and performance profile of the
system.

Reviewed-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Reviewed-by: Bjorn Andersson <bjorn.andersson@linaro.org>
Signed-off-by: Georgi Djakov <georgi.djakov@linaro.org>

interconnect: qcom: Add sdm845 interconnect provider driver

Introduce Qualcomm SDM845 specific provider driver using the
interconnect framework.

Signed-off-by: David Dai <daidavid1@codeaurora.org>
Acked-by: Rob Herring <robh@kernel.org>
Signed-off-by: Georgi Djakov <georgi.djakov@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

interconnect: Add generic on-chip interconnect API

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 node along the path
to support a bandwidth that satisfies all bandwidth requests that cross
through that node. The topology could be complicated and multi-tiered and
is SoC specific.

Reviewed-by: Evan Green <evgreen@chromium.org>
Signed-off-by: Georgi Djakov <georgi.djakov@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>