tree cfb1d7cec1dc0e7e3382efc64a2beb54f041799d
parent 7b76a1f5ed9c7233cfdd35b6f77310ccec293921
author Nicholas Piggin <npiggin@gmail.com> 1502469547 +1000
committer Michael Ellerman <mpe@ellerman.id.au> 1503496118 +1000

powerpc/64: Optimise set/clear of CTRL[RUN] (runlatch)

On modern CPUs the CTRL register is read-only except bit 63 which is
the run latch control. This means it can be updated with a mtspr
rather than mfspr/mtspr.

To accomodate older CPUs (Cell at least), where there are other bits
in the register, we still do a read/modify/write on pre 2.06 CPUs.

Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
[mpe: Update change log to mention 2.06 workaround]
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>