| aadb4b56 | 12-Mar-2025 |
Boyan Karatotev <boyan.karatotev@arm.com> |
refactor(psci): unify coherency exit between AArch64 and AArch32
The procedure is fairly simple: if we have hardware assisted coherency,
call into the cpu driver and let it do its thing. If we don't
refactor(psci): unify coherency exit between AArch64 and AArch32
The procedure is fairly simple: if we have hardware assisted coherency,
call into the cpu driver and let it do its thing. If we don't, then we
must turn data caches off, handle the confusion that causes with the
stack, and call into the cpu driver which will flush the caches that
need flushing.
On AArch32 the above happens in common code. On AArch64, however, the
turning off of the caches happens in the cpu driver. Since we're dealing
with the stack, we must exercise control over it and implement this in
assembly. But as the two implementations are nominally different (in the
ordering of operations), the part that is in assembly is quite large as
jumping back to C to handle the difference might involve the stack.
Presumably, the AArch difference was introduced in order to cater for a
possible implementation where turning off the caches requires an IMP DEF
sequence. Well, Arm no longer makes cores without hardware assisted
coherency, so this eventually is not possible.
So take this part out of the cpu driver and put it into common code,
just like in AArch32. With this, there is no longer a need call
prepare_cpu_pwr_dwn() in a different order either - we can delay it a
bit to happen after the stack management. So the two AArch-s flows
become identical. We can convert prepare_cpu_pwr_dwn() to C and leave
psci_do_pwrdown_cache_maintenance() only to exercise control over stack.
Change-Id: Ie4759ebe20bb74b60533c6a47dbc2b101875900f
Signed-off-by: Boyan Karatotev <boyan.karatotev@arm.com>
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| 5dd9dbb5 | 18-Nov-2016 |
Jeenu Viswambharan <jeenu.viswambharan@arm.com> |
Add provision to extend CPU operations at more levels
Various CPU drivers in ARM Trusted Firmware register functions to handle
power-down operations. At present, separate functions are registered to
Add provision to extend CPU operations at more levels
Various CPU drivers in ARM Trusted Firmware register functions to handle
power-down operations. At present, separate functions are registered to
power down individual cores and clusters.
This scheme operates on the basis of core and cluster, and doesn't cater
for extending the hierarchy for power-down operations. For example,
future CPUs might support multiple threads which might need powering
down individually.
This patch therefore reworks the CPU operations framework to allow for
registering power down handlers on specific level basis. Henceforth:
- Generic code invokes CPU power down operations by the level
required.
- CPU drivers explicitly mention CPU_NO_RESET_FUNC when the CPU has no
reset function.
- CPU drivers register power down handlers as a list: a mandatory
handler for level 0, and optional handlers for higher levels.
All existing CPU drivers are adapted to the new CPU operations framework
without needing any functional changes within.
Also update firmware design guide.
Change-Id: I1826842d37a9e60a9e85fdcee7b4b8f6bc1ad043
Signed-off-by: Jeenu Viswambharan <jeenu.viswambharan@arm.com>
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