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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
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Microwatt's hardware RNG is accessed using the DARN instruction.
Signed-off-by: Paul Mackerras <paulus@ozlabs.org>
Reviewed-by: Nicholas Piggin <npiggin@gmail.com>
Reviewed-by: Segher Boessenkool <segher@kernel.crashing.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/YMwXPHlV/ZleiQUY@thinks.paulus.ozlabs.org
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Microwatt is a FPGA-based implementation of the Power ISA. It
currently only implements little-endian 64-bit mode, and does
not (yet) support SMP, VMX, VSX or transactional memory. It has an
optional FPU, and an optional MMU (required for running Linux,
obviously) which implements a configurable radix tree but not
hypervisor mode or nested radix translation.
This adds a new machine type to support FPGA-based SoCs with a
Microwatt core. CONFIG_MATH_EMULATION can be selected for Microwatt
SOCs which don't have the FPU.
Signed-off-by: Paul Mackerras <paulus@ozlabs.org>
Reviewed-by: Nicholas Piggin <npiggin@gmail.com>
Reviewed-by: Segher Boessenkool <segher@kernel.crashing.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/YMwWbZVREsVug9R0@thinks.paulus.ozlabs.org
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