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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>
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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>
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ARM based platforms implement a variety of power management schemes that
allow processors to enter idle states at run-time.
The parameters defining these idle states vary on a per-platform basis forcing
the OS to hardcode the state parameters in platform specific static tables
whose size grows as the number of platforms supported in the kernel increases
and hampers device drivers standardization.
Therefore, this patch aims at standardizing idle state device tree bindings
for ARM platforms. Bindings define idle state parameters inclusive of entry
methods and state latencies, to allow operating systems to retrieve the
configuration entries from the device tree and initialize the related power
management drivers, paving the way for common code in the kernel to deal with
idle states and removing the need for static data in current and previous
kernel versions.
ARM64 platforms require the DT to define an entry-method property
for idle states.
On system implementing PSCI as an enable-method to enter low-power
states the PSCI CPU suspend method requires the power_state parameter to
be passed to the PSCI CPU suspend function.
This parameter is specific to a power state and platform specific,
therefore must be provided by firmware to the OS in order to enable
proper call sequence.
Thus, this patch also adds a property in the PSCI bindings that
describes how the PSCI CPU suspend power_state parameter should be
defined in DT in all device nodes that rely on PSCI CPU suspend method usage.
Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Acked-by: Daniel Lezcano <daniel.lezcano@linaro.org>
Acked-by: Nicolas Pitre <nico@linaro.org>
Reviewed-by: Rob Herring <robh@kernel.org>
Reviewed-by: Sebastian Capella <sebcape@gmail.com>
Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
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Lorenzo Pieralisi