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2025-02-26powerpc/microwatt: Add SMP supportPaul Mackerras
This adds support for Microwatt systems with more than one core, and updates the device tree for a 2-core version. The secondary CPUs are started and sent to spin in __secondary_hold very early on, in the platform probe function. The reason for doing this is so that they are there when smp_release_cpus() gets called, which is before the platform init_smp function or even the platform setup_arch function gets called. Note that having two CPUs in the device tree doesn't preclude operation with only one CPU. The SYSCON_CPU_CTRL register has a read-only field which indicates the number of CPU cores, so microwatt_init_smp() will only start as many CPU cores as are present in the system, and any extra CPU device-tree nodes will just be ignored. Signed-off-by: Paul Mackerras <paulus@ozlabs.org> Signed-off-by: Madhavan Srinivasan <maddy@linux.ibm.com> Link: https://patch.msgid.link/Z5xt8aooKyXZv6Kf@thinks.paulus.ozlabs.org