refactor(arm/common): gate coherency behind flag

Introduce a macro guard so platform coherency functions are only
compiled when HW_ASSISTED_COHERENCY is 0 (disabled). Many platforms
enable HW-assist

refactor(arm/common): gate coherency behind flag

Introduce a macro guard so platform coherency functions are only
compiled when HW_ASSISTED_COHERENCY is 0 (disabled). Many platforms
enable HW-assisted coherency by default, so compiling empty
definitions is unnecessary.

This refactor removes those empty functions for Arm CSS platforms.

Change-Id: I102ead46960e9da2d8b968f60cbfd3e5e5da1096
Signed-off-by: Ahmed Azeem <ahmed.azeem@arm.com>

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feat(dsu): support power control and autonomous powerdown config

This patch allows platforms to enable certain DSU settings
to ensure memory retention and control over
cache power requests. We also

feat(dsu): support power control and autonomous powerdown config

This patch allows platforms to enable certain DSU settings
to ensure memory retention and control over
cache power requests. We also move the driver out of css
into drivers/arm. Platforms can configure the
CLUSTERPWRCTLR and CLUSTERPWRDN registers [1] to improve
power efficiency.

These registers enable finer-grained control of
DSU power state transitions, including
powerdown and retention.

IMP_CLUSTERPWRCTLR_EL1 provides:
- Functional retention: Allows configuration of the
duration of inactivity before the DSU uses
CLUSTERPACTIVE to request functional retention.

- Cache power request: These bits are output on
CLUSTERPACTIVE[19:16] to indicate to the power controller
which cache portions must remain powered.

IMP_CLUSTERPWRDN_EL1 includes:
- Powerdown: Triggers full cluster powerdown, including
control logic.

- Memory retention: Requests memory retention mode,
keeping L3 RAM contents while powering off
the rest of the DSU.

The DSU-120 TRM [2] provides the full field definitions,
which are used as references in the `dsu_driver_data` structure.

References:
[1]: https://developer.arm.com/documentation/100453/latest/
[2]: https://developer.arm.com/documentation/102547/0201/?lang=en

Signed-off-by: Arvind Ram Prakash <arvind.ramprakash@arm.com>
Change-Id: I2eba808b8f2a27797782a333c65dd092b03208fe

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refactor: convert arm platforms to use the generic GIC driver

This reduces the code the platforms have to carry and makes their build
rules a bit simpler.

The main benefit is that plat_my_core_pos(

refactor: convert arm platforms to use the generic GIC driver

This reduces the code the platforms have to carry and makes their build
rules a bit simpler.

The main benefit is that plat_my_core_pos() no longer needs to be called
within the driver, helping with performance a bit.

Change-Id: I0b0d1d36d20d67c41c8c9dc14ade11bda6d4a6af
Signed-off-by: Boyan Karatotev <boyan.karatotev@arm.com>

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refactor(arm): simplify early platform setup function in BL2

Refactor `arm_bl2_early_platform_setup` to accept generic u_register_t
values, enabling support for firmware handoff boot arguments in
co

refactor(arm): simplify early platform setup function in BL2

Refactor `arm_bl2_early_platform_setup` to accept generic u_register_t
values, enabling support for firmware handoff boot arguments in
common code. This simplifies the interface for early platform setup.

Signed-off-by: Jayanth Dodderi Chidanand <jayanthdodderi.chidanand@arm.com>
Change-Id: Ie0dbe4d32bbef22bd185fdafe50091a2ea5f550f

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feat(arm): convert arm platforms to expect a wakeup

Newer cores in upcoming platforms may refuse to power down. The PSCI
library is already prepared for this so convert platform code to also
allow t

feat(arm): convert arm platforms to expect a wakeup

Newer cores in upcoming platforms may refuse to power down. The PSCI
library is already prepared for this so convert platform code to also
allow this. This is simple - drop the `wfi` + panic and let common code
deal with the fallout. The end result will be the same (sans the
message) except the platform will have fewer responsibilities. The only
exception is for cores being signalled to power off gracefully ahead of
system reset. That path must also be terminal so replace the end with
the same psci_pwrdown_cpu_end() to behave the same as the generic
implementation. It will handle wakeups and panic, hoping that the system
gets reset from under it. The dmb is upgraded to a dsb so no functional
change.

Change-Id: I381f96bec8532bda6ccdac65de57971aac42e7e8
Signed-off-by: Boyan Karatotev <boyan.karatotev@arm.com>

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feat(psci): allow cores to wake up from powerdown

The simplistic view of a core's powerdown sequence is that power is
atomically cut upon calling `wfi`. However, it turns out that it has
lots to do

feat(psci): allow cores to wake up from powerdown

The simplistic view of a core's powerdown sequence is that power is
atomically cut upon calling `wfi`. However, it turns out that it has
lots to do - it has to talk to the interconnect to exit coherency, clean
caches, check for RAS errors, etc. These take significant amounts of
time and are certainly not atomic. As such there is a significant window
of opportunity for external events to happen. Many of these steps are
not destructive to context, so theoretically, the core can just "give
up" half way (or roll certain actions back) and carry on running. The
point in this sequence after which roll back is not possible is called
the point of no return.

One of these actions is the checking for RAS errors. It is possible for
one to happen during this lengthy sequence, or at least remain
undiscovered until that point. If the core were to continue powerdown
when that happens, there would be no (easy) way to inform anyone about
it. Rejecting the powerdown and letting software handle the error is the
best way to implement this.

Arm cores since at least the a510 have included this exact feature. So
far it hasn't been deemed necessary to account for it in firmware due to
the low likelihood of this happening. However, events like GIC wakeup
requests are much more probable. Older cores will powerdown and
immediately power back up when this happens. Travis and Gelas include a
feature similar to the RAS case above, called powerdown abandon. The
idea is that this will improve the latency to service the interrupt by
saving on work which the core and software need to do.

So far firmware has relied on the `wfi` being the point of no return and
if it doesn't explicitly detect a pending interrupt quite early on, it
will embark onto a sequence that it expects to end with shutdown. To
accommodate for it not being a point of no return, we must undo all of
the system management we did, just like in the warm boot entrypoint.

To achieve that, the pwr_domain_pwr_down_wfi hook must not be terminal.
Most recent platforms do some platform management and finish on the
standard `wfi`, followed by a panic or an endless loop as this is
expected to not return. To make this generic, any platform that wishes
to support wakeups must instead let common code call
`psci_power_down_wfi()` right after. Besides wakeups, this lets common
code handle powerdown errata better as well.

Then, the CPU_OFF case is simple - PSCI does not allow it to return. So
the best that can be done is to attempt the `wfi` a few times (the
choice of 32 is arbitrary) in the hope that the wakeup is transient. If
it isn't, the only choice is to panic, as the system is likely to be in
a bad state, eg. interrupts weren't routed away. The same applies for
SYSTEM_OFF, SYSTEM_RESET, and SYSTEM_RESET2. There the panic won't
matter as the system is going offline one way or another. The RAS case
will be considered in a separate patch.

Now, the CPU_SUSPEND case is more involved. First, to powerdown it must
wipe its context as it is not written on warm boot. But it cannot be
overwritten in case of a wakeup. To avoid the catch 22, save a copy that
will only be used if powerdown fails. That is about 500 bytes on the
stack so it hopefully doesn't tip anyone over any limits. In future that
can be avoided by having a core manage its own context.

Second, when the core wakes up, it must undo anything it did to prepare
for poweroff, which for the cores we care about, is writing
CPUPWRCTLR_EL1.CORE_PWRDN_EN. The least intrusive for the cpu library
way of doing this is to simply call the power off hook again and have
the hook toggle the bit. If in the future there need to be more complex
sequences, their direction can be advised on the value of this bit.

Third, do the actual "resume". Most of the logic is already there for
the retention suspend, so that only needs a small touch up to apply to
the powerdown case as well. The missing bit is the powerdown specific
state management. Luckily, the warmboot entrypoint does exactly that
already too, so steal that and we're done.

All of this is hidden behind a FEAT_PABANDON flag since it has a large
memory and runtime cost that we don't want to burden non pabandon cores
with.

Finally, do some function renaming to better reflect their purpose and
make names a little bit more consistent.

Change-Id: I2405b59300c2e24ce02e266f91b7c51474c1145f
Signed-off-by: Boyan Karatotev <boyan.karatotev@arm.com>

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fix(css): turn the redistributor off on PSCI CPU_OFF

When GICR_WAKER.ProcessorSleep == 1 (i.e. after gicv3_cpuif_disable())
the GIC will assert the WakeRequest signal to try and wake the core up
ins

fix(css): turn the redistributor off on PSCI CPU_OFF

When GICR_WAKER.ProcessorSleep == 1 (i.e. after gicv3_cpuif_disable())
the GIC will assert the WakeRequest signal to try and wake the core up
instead of delivering an interrupt. This is useful when a core is in
some kind of suspend state.

However, when the core is properly off (CPU_OFF), it shouldn't get woken
up in any way other than a CPU_ON call. In the general case interrupts
would be routed away so this doesn't matter. But in case they aren't, we
want the core to stay off.

So turn the redistributor off on CPU_OFF calls. This will prevent the
WakeRequest from being sent.

Change-Id: I7f20591d1c83a4a9639281ef86caa79d6669b536
Signed-off-by: Boyan Karatotev <boyan.karatotev@arm.com>

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feat(tc): add save/restore DSU PMU register support

This patch adds support for preserving DSU PMU registers
over a power cycle in TC platform.

These PMU registers need to be manually saved/restore

feat(tc): add save/restore DSU PMU register support

This patch adds support for preserving DSU PMU registers
over a power cycle in TC platform.

These PMU registers need to be manually saved/restored
because they are part of cluster power domain and OS
doesn't know when DSU is powered OFF.

Change-Id: Ife9573f205d99d092039cb95674e7434bb5f9239
Signed-off-by: Arvind Ram Prakash <arvind.ramprakash@arm.com>

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