cpuidle: dt: Replace deprecated strncpy() with strscpy()

`strncpy` is deprecated for use on NUL-terminated destination strings [1].

We should prefer more robust and less ambiguous string interfaces.

A suitable replacement is `strscpy` [2] due to the fact that it guarantees
NUL-termination on the destination buffer. With this, we can also drop
the now unnecessary `CPUIDLE_(NAME|DESC)_LEN - 1` pieces.

Link: https://www.kernel.org/doc/html/latest/process/deprecated.html#strncpy-on-nul-terminated-strings [1]
Link: https://manpages.debian.org/testing/linux-manual-4.8/strscpy.9.en.html [2]
Link: https://github.com/KSPP/linux/issues/90
Cc: linux-hardening@vger.kernel.org
Signed-off-by: Justin Stitt <justinstitt@google.com>
Reviewed-by: Kees Cook <keescook@chromium.org>
Link: https://lore.kernel.org/r/20230913-strncpy-drivers-cpuidle-dt_idle_states-c-v1-1-d16a0dbe5658@google.com
Signed-off-by: Kees Cook <keescook@chromium.org>

cpuidle: Adjust includes to remove of_device.h

Now that of_cpu_device_node_get() is defined in of.h, of_device.h is just
implicitly including other includes, and is no longer needed. Adjust the
include files with what was implicitly included by of_device.h (cpu.h,
cpuhotplug.h, of.h, and of_platform.h) and drop including of_device.h.

Acked-by: Anup Patel <anup@brainfault.org>
Acked-by: Rafael J. Wysocki <rafael@kernel.org>
Acked-by: Sudeep Holla <sudeep.holla@arm.com>
Link: https://lore.kernel.org/r/20230329-dt-cpu-header-cleanups-v1-16-581e2605fe47@kernel.org
Signed-off-by: Rob Herring <robh@kernel.org>

cpuidle, dt: Push RCU-idle into driver

Doing RCU-idle outside the driver, only to then temporarily enable it
again before going idle is suboptimal.

Notably: this converts all dt_init_idle_driver() and
__CPU_PM_CPU_IDLE_ENTER() users for they are inextrably intertwined.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Tested-by: Tony Lindgren <tony@atomide.com>
Tested-by: Ulf Hansson <ulf.hansson@linaro.org>
Acked-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Acked-by: Frederic Weisbecker <frederic@kernel.org>
Link: https://lore.kernel.org/r/20230112195540.068981667@infradead.org

cpuidle: dt: Clarify a comment and simplify code in dt_init_idle_driver()

The drv->state_count is assigned the total number of available states, so
let's make that clear.

Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
Reviewed-by: Sudeep Holla <sudeep.holla@arm.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

cpuidle: dt: Return the correct numbers of parsed idle states

While we correctly skips to initialize an idle state from a disabled idle
state node in DT, the returned value from dt_init_idle_driver() don't get
adjusted accordingly. Instead the number of found idle state nodes are
returned, while the callers are expecting the number of successfully
initialized idle states from DT.

This leads to cpuidle drivers unnecessarily continues to initialize their
idle state specific data. Moreover, in the case when all idle states have
been disabled in DT, we would end up registering a cpuidle driver, rather
than relying on the default arch specific idle call.

Fixes: 9f14da345599 ("drivers: cpuidle: implement DT based idle states infrastructure")
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
Reviewed-by: Sudeep Holla <sudeep.holla@arm.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

cpuidle: dt: Support hierarchical CPU idle states

Currently CPU's idle states are represented using the flattened model.
Let's add support for the hierarchical layout, via converting to use
of_get_cpu_state_node().

Suggested-by: Sudeep Holla <sudeep.holla@arm.com>
Signed-off-by: Lina Iyer <lina.iyer@linaro.org>
Reviewed-by: Daniel Lezcano <daniel.lezcano@linaro.org>
Co-developed-by: Ulf Hansson <ulf.hansson@linaro.org>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
Reviewed-by: Sudeep Holla <sudeep.holla@arm.com>
Acked-by: Rafael J. Wysocki <rafael@kernel.org>

treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 500

Based on 2 normalized pattern(s):

this program is free software you can redistribute it and or modify
it under the terms of the gnu general public license version 2 as
published by the free software foundation

this program is free software you can redistribute it and or modify
it under the terms of the gnu general public license version 2 as
published by the free software foundation #

extracted by the scancode license scanner the SPDX license identifier

GPL-2.0-only

has been chosen to replace the boilerplate/reference in 4122 file(s).

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Enrico Weigelt <info@metux.net>
Reviewed-by: Kate Stewart <kstewart@linuxfoundation.org>
Reviewed-by: Allison Randal <allison@lohutok.net>
Cc: linux-spdx@vger.kernel.org
Link: https://lkml.kernel.org/r/20190604081206.933168790@linutronix.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

cpuidle: dt: bail out if the idle-state DT node is not compatible

Currently, the DT of the idle states will be parsed first whether it's
compatible or not. This could cause a warning message that comes from if
the CPU doesn't support identical idle states. E.g. Tegra186 can run
with 2 Cortex-A57 and 2 Denver cores with different idle states on
different types of these cores.

So fix it by checking the match node earlier, then it can make sure it
only goes through the idle states that the CPU supported.

Signed-off-by: Joseph Lo <josephl@nvidia.com>
Reviewed-by: Sudeep Holla <sudeep.holla@arm.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

cpuidle: Convert to using %pOF instead of full_name

Now that we have a custom printf format specifier, convert users of
full_name to use %pOF instead. This is preparation to remove storing
of the full path string for each node.

Signed-off-by: Rob Herring <robh@kernel.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

PM / s2idle: Rename ->enter_freeze to ->enter_s2idle

Rename the ->enter_freeze cpuidle driver callback to ->enter_s2idle
to make it clear that it is used for entering suspend-to-idle and
rename the related functions, variables and so on accordingly.

Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

cpuidle: dt: Add missing 'of_node_put()'

'of_node_put()' should be called on pointer returned by
'of_parse_phandle()' when done. In this function this is done in all path
except this 'continue', so add it.

Fixes: 97735da074fd (drivers: cpuidle: Add status property to ARM idle states)
Signed-off-by: Christophe Jaillet <christophe.jaillet@wanadoo.fr>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

cpuidle: dt: assign ->enter_freeze to same as ->enter callback function

enter_freeze() callback is expected atleast to do the same as enter()
but it has to guarantee that interrupts aren't enabled at any point
in its execution, as the tick is frozen.

CPUs execute ->enter_freeze with the local tick or entire timekeeping
suspended, so it must not re-enable interrupts at any point (even
temporarily) or attempt to change states of clock event devices.

It will be called when the system goes to suspend-to-idle and will
reduce power usage because CPUs won't be awaken for unnecessary IRQs
(i.e. woken up only on IRQs from "wakeup sources")

We can reuse the same code for both the enter() and enter_freeze()
callbacks as along as they don't re-enable interrupts. Only "coupled"
cpuidle mechanism enables interrupts and doing that with timekeeping
suspended is generally not safe.

Since this generic DT based idle driver doesn't support "coupled"
states, it is safe to assume that the interrupts are not re-enabled.

This patch assign enter_freeze to same as enter callback function which
helps to save power without any intermittent spurious wakeups from
suspend-to-idle.

Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>
Tested-by: Andy Gross <andy.gross@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

drivers: cpuidle: Add idle-state-name description to ARM idle states

On ARM machines, where generally speaking the idle state numbering has
no fixed and standard meaning it is useful to provide a description
of the idle state inner workings for benchmarking and monitoring purposes.

This patch adds a property to the idle states bindings that if present
gives platform firmware a means of describing the idle state and export
the string description to user space.

The patch updates the DT parsing code accordingly to take the description,
if present, into consideration.

Acked-by: Kevin Hilman <khilman@linaro.org>
Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>

drivers: cpuidle: Add status property to ARM idle states

On some platforms the device tree bindings must provide the kernel
with a status flag for idle states, that defines whether the idle
state is operational or not in the current configuration.

This patch adds a status property to the ARM idle states compliant
with ePAPR v1.1 and updates the DT parsing code accordingly.

Acked-by: Kevin Hilman <khilman@linaro.org>
Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>

cpuidle: Invert CPUIDLE_FLAG_TIME_VALID logic

The only place where the time is invalid is when the ACPI_CSTATE_FFH entry
method is not set. Otherwise for all the drivers, the time can be correctly
measured.

Instead of duplicating the CPUIDLE_FLAG_TIME_VALID flag in all the drivers
for all the states, just invert the logic by replacing it by the flag
CPUIDLE_FLAG_TIME_INVALID, hence we can set this flag only for the acpi idle
driver, remove the former flag from all the drivers and invert the logic with
this flag in the different governor.

Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

drivers: cpuidle: implement DT based idle states infrastructure

On most common ARM systems, the low-power states a CPU can be put into are
not discoverable in HW and require device tree bindings to describe
power down suspend operations and idle states parameters.

In order to enable DT based idle states and configure idle drivers, this
patch implements the bulk infrastructure required to parse the device tree
idle states bindings and initialize the corresponding CPUidle driver states
data.

The parsing API accepts a start index that defines the first idle state
that should be initialized by the parsing code in order to give new and
legacy driver flexibility over which states should be parsed using the
new DT mechanism.

The idle states node(s) is obtained from the phandle list of the first cpu
in the driver cpumask; the kernel checks that the idle state node phandle
is the same for all CPUs in the driver cpumask before declaring the idle state
as valid and start parsing its content.

The idle state enter function pointer is initialized through DT match
structures passed in by the CPUidle driver, so that ARM legacy code can
cope with platform specific idle entry method based on compatible
string matching and the code used to initialize the enter function pointer
can be moved to the DT generic layer.

Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Acked-by: Daniel Lezcano <daniel.lezcano@linaro.org>
Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>