This series is an updated version of a previous posting available here: http://lists.infradead.org/pipermail/linux-arm-kernel/2012-January/080868.html
The introduction of multi-cluster ARM systems in SoC designs requires the kernel to become cluster aware, so that it can be booted on every CPU in the system and it can build an appropriate HW-to-logical cpu map. Current code in the kernel, in particular the boot sequence, hinges upon a sequential mapping of MPIDR values for cpus and related interrupt controller CPU interfaces to logical cpu indexing. This hypothesis is not valid when the concept of cluster is introduced since the MPIDR cannot be represented as a single index and interrupt controller CPU interfaces can be wired with a numbering scheme following per-SoC design parameters which can be only detected through probing or device tree representation. Through the device tree and "cpu" nodes bindings, the kernel is provided with HW values for MPIDR registers that allow the kernel to identify the HW CPU ids that are present in the platform. The GIC code has been extended to allow automatic detection of GIC CPU IF ids at boot. IPIs are broadcast to all possible CPUs, and every time a secondary CPU is booted, it initializes its own mask and clears itself from the mask of all other logical CPUs. The device tree bindings and GIC probing allow to boot the Linux kernel on any CPU of a multi-cluster system without relying on a platform specific hook to identify the number of CPUs and hypothesis on the sequential pattern of MPIDRs and relative GIC CPU IF ids. Pen release code for all converted platforms will need patching to extend the current MPIDR range check; this will be done as soon as the bindings and code for the multi-cluster boot protocol will be reviewed and accepted. The patchset has been tested on: - TC2 testchip to boot a 5-core dual-cluster system on every possible CPU. Lorenzo Pieralisi (3): ARM: kernel: add device tree init map function ARM: kernel: add cpu logical map DT init in setup_arch ARM: kernel: add logical mappings look-up Nicolas Pitre (1): ARM: gic: use a private mapping for CPU target interfaces Documentation/devicetree/bindings/arm/cpus.txt | 42 +++++++++++++++++++++++ arch/arm/common/gic.c | 42 ++++++++++++++++++----- arch/arm/include/asm/prom.h | 2 ++ arch/arm/include/asm/smp_plat.h | 17 ++++++++++ arch/arm/kernel/devtree.c | 47 ++++++++++++++++++++++++++ arch/arm/kernel/setup.c | 1 + 6 files changed, 143 insertions(+), 8 deletions(-) create mode 100644 Documentation/devicetree/bindings/arm/cpus.txt -- 1.7.12 _______________________________________________ devicetree-discuss mailing list [email protected] https://lists.ozlabs.org/listinfo/devicetree-discuss
