Re: simplified RISC-V interrupt and clocksource handling v2

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On Thu, 02 Aug 2018 04:49:57 PDT (-0700), Christoph Hellwig wrote:
This series tries adds support for interrupt handling and timers
for the RISC-V architecture.

The basic per-hart interrupt handling implemented by the scause
and sie CSRs is extremely simple and implemented directly in
arch/riscv/kernel/irq.c.  In addition there is a irqchip driver
for the PLIC external interrupt controller, which is called through
the set_handle_irq API, and a clocksource driver that gets its
timer interrupt directly from the low-level interrupt handling.

Compared to previous iterations this version does not try to use an
irqchip driver for the low-level interrupt handling.  This saves
a couple indirect calls and an additional read of the scause CSR
in the hot path, makes the code much simpler and last but not least
avoid the dependency on a device tree for a mandatory architectural
feature.

A git tree is available here (contains a few more patches before
the ones in this series)

    git://git.infradead.org/users/hch/riscv.git riscv-irq-simple.2

Gitweb:

    http://git.infradead.org/users/hch/riscv.git/shortlog/refs/heads/riscv-irq-simple.2

Changes since v1:
 - rename the plic driver to irq-sifive-plic
 - switch to a default compatible of sifive,plic0 (still supporting the
   riscv,plic0 name for compatibility)
 - add a reference for the SiFive PLIC register layout
 - fix plic_toggle addressing for large numbers of hwirqs
 - remove the call to ack_bad_irq
 - use a raw spinlock for plic_toggle_lock
 - use the irq_desc cpumask in the plic enable/disable methods
 - add back OF contexid parsing in the plic driver
 - don't allow COMPILE_TEST builds of the clocksource driver, as it
   depends on <asm/sbi.h>
 - default the clocksource driver to y
 - clean up naming in the clocksource driver
 - remove the MINDELTA and MAXDELTA #defines
 - various DT binding fixes

Ah, thank you so much. This is great! With this patch set applied on top of rc7 I can boot QEMU master and get to the Fedora root file system. I'll review the patch set properly, but at least for now I think a

Tested-by: Palmer Dabbelt <palmer@xxxxxxxxxx>

is warranted. What's the best way to go about merging this? There's quite a bit of arch/riscv diff here so I don't mind taking it through the RISC-V tree, but there's also some irqchip and clocksource stuff as well so I'm not sure if that's OK to do.
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