ARM based systems embed power management HW that allows SW to enter low-power states according to run-time criteria based on parameters (eg power state entry/exit latency) that define how a power state has to be managed and its respective properties. ARM partners implement HW power management schemes through custom HW, with power controllers and relative control mechanisms differing on both HW implementations and the way SW can control them. This differentiation forces PM software in the kernel to cope with states differences in power management drivers, which cause code fragmentation and duplication of functionality. Most of the power control scheme HW parameters are not probeable on ARM platforms from a SW point of view, hence, in order to tackle the drivers fragmentation problem, this patch series defines device tree bindings to describe power states parameters on ARM platforms. Device tree bindings for power states also require the introduction of device tree bindings for processor caches, since power states entry/exit require SW cache maintainance; in some ARM systems, where firmware does not support power down interfaces, cache maintainance must be carried out in the OS power management layer, which then requires a description of the cache topology through device tree nodes. The power states on ARM are described as "C-states" in this patchset, borrowing the nomenclature from ACPI power states bindings which have by now been widely adopted on both x86 and ARM world as power states names. C-states device tree standardization shares most of the concepts and definitions with the ongoing ACPI ARM C-state bindings proposal so that both standards can contain a coherent set of parameters, simplifying the way SW will have to handle the respective device drivers. Lorenzo Pieralisi (2): Documentation: arm: add cache DT bindings Documentation: arm: define DT C-states bindings Documentation/devicetree/bindings/arm/c-states.txt | 830 +++++++++++++++++++++ Documentation/devicetree/bindings/arm/cache.txt | 25 + 2 files changed, 855 insertions(+) create mode 100644 Documentation/devicetree/bindings/arm/c-states.txt create mode 100644 Documentation/devicetree/bindings/arm/cache.txt -- 1.8.4 -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
