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MIPS: Add Loongson-3B support
Loongson-3B is a 8-cores processor. In general it looks like there are
two Loongson-3A integrated in one chip: 8 cores are separated into two
groups (two NUMA node), each node has its own local memory.
Of course there are some differences between one Loongson-3B and two
Loongson-3A. E.g., the base addresses of IPI registers of each node are
not the same; Loongson-3A use ChipConfig register to enable/disable
clock, but Loongson-3B use FreqControl register instead.
There are two revision of Loongson-3B, the first revision is called as
Loongson-3B1000, whose frequency is 1GHz and has a PRid 0x6306, the
second revision is called as Loongson-3B1500, whose frequency is 1.5GHz
and has a PRid 0x6307. Both revisions has a bug that clock cannot be
disabled at runtime, but this will be fixed in future.
Loongson-3 is a multi-core MIPS family CPU, it support MIPS64R2 fully.
Loongson-3 has the same IMP field (0x6300) as Loongson-2.
Loongson-3 has a hardware-maintained cache, system software doesn't
need to maintain coherency.
Loongson-3A is the first revision of Loongson-3, and it is the quad-
core version of Loongson-2G. Loongson-3A has a simplified version named
Loongson-2Gq, the main difference between Loongson-3A/2Gq is 3A has two
HyperTransport controller but 2Gq has only one. HT0 is used for cross-
chip interconnection and HT1 is used to link PCI bus. Therefore, 2Gq
cannot support NUMA but 3A can. For software, Loongson-2Gq is simply
identified as Loongson-3A. |
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