Currently cpu hotplug with the PREEMPT_RT option set in the kernel is
not supported because the underlying generic power domain functions
used in the cpu hotplug callbacks are incompatible from a lock point
of view. This situation prevents the suspend to idle to reach the
deepest idle state for the "cluster" as identified in the
undermentioned commit.

Use the compatible ones when PREEMPT_RT is enabled and remove the
boolean disabling the hotplug callbacks with this option.

With this change the platform can reach the deepest idle state
allowing at suspend time to consume less power.

Tested-on Lenovo T14s with the following script:

echo 0 > /sys/devices/system/cpu/cpu3/online
BEFORE=$(cat /sys/kernel/debug/pm_genpd/power-domain-cpu-cluster0/idle_states | grep S0 | awk '{ print $3 }') ;
rtcwake -s 1 -m mem;
AFTER=$(cat /sys/kernel/debug/pm_genpd/power-domain-cpu-cluster0/idle_states | grep S0 | awk '{ print $3 }');
if [ $BEFORE -lt $AFTER ]; then
    echo "Test successful"
else
    echo "Test failed"
fi
echo 1 > /sys/devices/system/cpu/cpu3/online

Fixes: 1c4b2932bd62 ("cpuidle: psci: Enable the hierarchical topology for s2idle on PREEMPT_RT")
Cc: Raghavendra Kakarla <quic_rkakarla@quicinc.com>
Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>
Reviewed-by: Sudeep Holla <sudeep.holla@arm.com>
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/r/20250709154728.733920-1-daniel.lezcano@linaro.org
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>

Fix an issue in the PSCI cpuidle driver introduced recently and a nasty
x86 power regression introduced in 6.15:

 - Prevent freeing an uninitialized pointer in error path of
   dt_idle_state_present() in the PSCI cpuidle driver (Dan Carpenter).

 - Revert an x86 commit that went into 6.15 and caused idle power,
   including power in suspend-to-idle, to rise rather dramatically on
   systems booting with "nosmt" in the kernel command line (Rafael Wysocki).

* pm-cpuidle:
  Revert "x86/smp: Eliminate mwait_play_dead_cpuid_hint()"
  cpuidle: psci: Fix uninitialized variable in dt_idle_state_present()

Pull power management updates from Rafael Wysocki:
 "Once again, the changes are dominated by cpufreq updates, but this
  time the majority of them are cpufreq core changes, mostly related to
  the introduction of policy locking guards and __free() usage, and
  fixes related to boost handling.

  Still, there is also a significant update of the intel_pstate driver
  making it register an energy model when running on a hybrid platform
  which is used for enabling energy-aware scheduling (EAS) if the driver
  operates in the passive mode (and schedutil is used as the cpufreq
  governor for all CPUs which is the passive mode default).

  There are some amd-pstate driver updates too, for a good measure,
  including the "Requested CPU Min frequency" BIOS option support and
  new online/offline callbacks.

  In the cpuidle space, the most significant change is the addition of a
  C1 demotion on/off sysfs knob to intel_idle which should help some
  users to configure their systems more precisely. There is also the
  conversion of the PSCI cpuidle driver to a faux device one and there
  are two small updates of cpuidle governors.

  Device power management is also modified quite a bit, especially the
  handling of devices with asynchronous suspend and resume enabled
  during system transitions. They are now going to be handled more
  asynchronously during suspend transitions and somewhat less
  aggressively during resume transitions.

  Apart from the above, the operating performance points (OPP) library
  is now going to use mutex locking guards and scope-based cleanup
  helpers and there is the usual bunch of assorted fixes and code
  cleanups.

  Specifics:

   - Fix potential division-by-zero error in em_compute_costs() (Yaxiong
     Tian)

   - Fix typos in energy model documentation and example driver code
     (Moon Hee Lee, Atul Kumar Pant)

   - Rearrange the energy model management code and add a new function
     for adjusting a CPU energy model after adjusting the capacity of
     the given CPU to it (Rafael Wysocki)

   - Refactor cpufreq_online(), add and use cpufreq policy locking
     guards, use __free() in policy reference counting, and clean up
     core cpufreq code on top of that (Rafael Wysocki)

   - Fix boost handling on CPU suspend/resume and sysfs updates (Viresh
     Kumar)

   - Fix des_perf clamping with max_perf in amd_pstate_update()
     (Dhananjay Ugwekar)

   - Add offline, online and suspend callbacks to the amd-pstate driver,
     rename and use the existing amd_pstate_epp callbacks in it
     (Dhananjay Ugwekar)

   - Add support for the "Requested CPU Min frequency" BIOS option to
     the amd-pstate driver (Dhananjay Ugwekar)

   - Reset amd-pstate driver mode after running selftests (Swapnil
     Sapkal)

   - Avoid shadowing ret in amd_pstate_ut_check_driver() (Nathan
     Chancellor)

   - Add helper for governor checks to the schedutil cpufreq governor
     and move cpufreq-specific EAS checks to cpufreq (Rafael Wysocki)

   - Populate the cpu_capacity sysfs entries from the intel_pstate
     driver after registering asym capacity support (Ricardo Neri)

   - Add support for enabling Energy-aware scheduling (EAS) to the
     intel_pstate driver when operating in the passive mode on a hybrid
     platform (Rafael Wysocki)

   - Drop redundant cpus_read_lock() from store_local_boost() in the
     cpufreq core (Seyediman Seyedarab)

   - Replace sscanf() with kstrtouint() in the cpufreq code and use a
     symbol instead of a raw number in it (Bowen Yu)

   - Add support for autonomous CPU performance state selection to the
     CPPC cpufreq driver (Lifeng Zheng)

   - OPP: Add dev_pm_opp_set_level() (Praveen Talari)

   - Introduce scope-based cleanup headers and mutex locking guards in
     OPP core (Viresh Kumar)

   - Switch OPP to use kmemdup_array() (Zhang Enpei)

   - Optimize bucket assignment when next_timer_ns equals KTIME_MAX in
     the menu cpuidle governor (Zhongqiu Han)

   - Convert the cpuidle PSCI driver to a faux device one (Sudeep Holla)

   - Add C1 demotion on/off sysfs knob to the intel_idle driver (Artem
     Bityutskiy)

   - Fix typos in two comments in the teo cpuidle governor (Atul Kumar
     Pant)

   - Fix denying of auto suspend in pm_suspend_timer_fn() (Charan Teja
     Kalla)

   - Move debug runtime PM attributes to runtime_attrs[] (Rafael
     Wysocki)

   - Add new devm_ functions for enabling runtime PM and runtime PM
     reference counting (Bence Csókás)

   - Remove size arguments from strscpy() calls in the hibernation core
     code (Thorsten Blum)

   - Adjust the handling of devices with asynchronous suspend enabled
     during system suspend and resume to start resuming them immediately
     after resuming their parents and to start suspending such a device
     immediately after suspending its first child (Rafael Wysocki)

   - Adjust messages printed during tasks freezing to avoid using
     pr_cont() (Andrew Sayers, Paul Menzel)

   - Clean up unnecessary usage of !! in pm_print_times_init() (Zihuan
     Zhang)

   - Add missing wakeup source attribute relax_count to sysfs and remove
     the space character at the end ofi the string produced by
     pm_show_wakelocks() (Zijun Hu)

   - Add configurable pm_test delay for hibernation (Zihuan Zhang)

   - Disable asynchronous suspend in ucsi_ccg_probe() to prevent the
     cypd4226 device on Tegra boards from suspending prematurely (Jon
     Hunter)

   - Unbreak printing PM debug messages during hibernation and clean up
     some related code (Rafael Wysocki)

   - Add a systemd service to run cpupower and change cpupower binding's
     Makefile to use -lcpupower (John B. Wyatt IV, Francesco Poli)"

* tag 'pm-6.16-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm: (72 commits)
  cpufreq: CPPC: Add support for autonomous selection
  cpufreq: Update sscanf() to kstrtouint()
  cpufreq: Replace magic number
  OPP: switch to use kmemdup_array()
  PM: freezer: Rewrite restarting tasks log to remove stray *done.*
  PM: runtime: fix denying of auto suspend in pm_suspend_timer_fn()
  cpufreq: drop redundant cpus_read_lock() from store_local_boost()
  cpupower: do not install files to /etc/default/
  cpupower: do not call systemctl at install time
  cpupower: do not write DESTDIR to cpupower.service
  PM: sleep: Introduce pm_sleep_transition_in_progress()
  cpufreq/amd-pstate: Avoid shadowing ret in amd_pstate_ut_check_driver()
  cpufreq: intel_pstate: Document hybrid processor support
  cpufreq: intel_pstate: EAS: Increase cost for CPUs using L3 cache
  cpufreq: intel_pstate: EAS support for hybrid platforms
  PM: EM: Introduce em_adjust_cpu_capacity()
  PM: EM: Move CPU capacity check to em_adjust_new_capacity()
  PM: EM: Documentation: Fix typos in example driver code
  cpufreq: Drop policy locking from cpufreq_policy_is_good_for_eas()
  PM: sleep: Introduce pm_suspend_in_progress()
  ...

If the first cpu_node = of_cpu_device_node_get() fails then the cleanup.h
code will try to free "state_node" but it hasn't been initialized yet.
Declare the device_nodes where they are initialized to fix this.

Fixes: 5836ebeb4a2b ("cpuidle: psci: Avoid initializing faux device if no DT idle states are present")
Signed-off-by: Dan Carpenter <dan.carpenter@linaro.org>
Link: https://patch.msgid.link/aDVRcfU8O8sez1x7@stanley.mountain
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

Commit af5376a77e87 ("cpuidle: psci: Transition to the faux device interface")
transitioned the PSCI cpuidle driver from using a platform device to the
faux device framework. However, unlike platform devices, the faux device
infrastructure logs an error when the probe function fails, even if the
failure is intentional or expected.

To prevent unnecessary error logs, we can skip creating the faux device
entirely if there are no PSCI idle states defined in the device tree.
Introduce a check for DT idle states during initialization and avoid
setting up the device if none are found.

This ensures cleaner logs and avoids misleading probe failure messages
when PSCI idle support is intentionally not described in DT.

Fixes: af5376a77e87 ("cpuidle: psci: Transition to the faux device interface")
Reported-by: Jon Hunter <jonathanh@nvidia.com>
Closes: https://lore.kernel.org/r/cf4e70e4-9fe5-4697-8744-8c12c41b5ff9@nvidia.com
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>
Reviewed-by: Ulf Hansson <ulf.hansson@linaro.org>
Link: https://patch.msgid.link/20250502140119.2578909-1-sudeep.holla@arm.com
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

When trying to enter a domain-idlestate, we may occasionally fail to enter
the state, which is informed to us by psci_cpu_suspend_enter() returning an
error-code. In these cases, our corresponding genpd->power_off() callback
has already returned zero to indicate success, leading to getting
in-correct domain-idlestate statistics in debugfs for the genpd in
question.

Let's fix this by making use of the new pm_genpd_inc_rejected() helper, as
it allows us to correct the domain-idlestate statistics for this type of
scenario.

Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
Link: https://lore.kernel.org/r/20250314100103.1294715-4-ulf.hansson@linaro.org

To prepare to extend the per CPU variable domain_state to include more
data, let's move it into a struct. A subsequent change will add the new
data. This change have no intended functional impact.

Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
Link: https://lore.kernel.org/r/20250314100103.1294715-3-ulf.hansson@linaro.org

The PSCI cpuidle driver does not require the creation of a platform
device. Originally, this approach was chosen for simplicity when the
driver was first implemented.

With the introduction of the lightweight faux device interface, we now
have a more appropriate alternative. Migrate the driver to utilize the
faux bus, given that the platform device it previously created was not
a real one anyway. This will simplify the code, reducing its footprint
while maintaining functionality.

Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>
Link: https://patch.msgid.link/20250317-plat2faux_dev-v1-1-5fe67c085ad5@arm.com
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

Directly assign the last bucket value instead of calling which_bucket()
when next_timer_ns equals KTIME_MAX, the largest possible value that
always falls into the last bucket.

This avoids unnecessary calculations and enhances performance.

Reviewed-by: Christian Loehle <christian.loehle@arm.com>
Signed-off-by: Zhongqiu Han <quic_zhonhan@quicinc.com>
Link: https://patch.msgid.link/20250405135308.1854342-1-quic_zhonhan@quicinc.com
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

Fix a typo and correct a spelling mistake in comments.

Signed-off-by: Atul Kumar Pant <atulpant.linux@gmail.com>
Link: https://patch.msgid.link/20250405060909.2026332-1-atulpant.linux@gmail.com
[ rjw: Subject and changelog edits ]
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>