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| author | Nicholas Piggin <npiggin@gmail.com> | 2019-07-11 04:24:03 +0200 |
|---|---|---|
| committer | Michael Ellerman <mpe@ellerman.id.au> | 2020-01-16 05:59:37 +0100 |
| commit | ed0bc98f8cbe4f8254759d333a47aedc816ff8c5 (patch) | |
| tree | 7e5768afb6d7e895930d578954d3c4061998cb9a /arch/powerpc/kernel/idle.c | |
| parent | misc: cxl: use mmgrab (diff) | |
| download | linux-ed0bc98f8cbe4f8254759d333a47aedc816ff8c5.tar.xz linux-ed0bc98f8cbe4f8254759d333a47aedc816ff8c5.zip | |
powerpc/64s: Reimplement power4_idle code in C
This implements the tricky tracing and soft irq handling bits in C,
leaving the low level bit to asm.
A functional difference is that this redirects the interrupt exit to
a return stub to execute blr, rather than the lr address itself. This
is probably barely measurable on real hardware, but it keeps the link
stack balanced.
Tested with QEMU.
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
[mpe: Move power4_fixup_nap back into exceptions-64s.S]
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20190711022404.18132-1-npiggin@gmail.com
Diffstat (limited to 'arch/powerpc/kernel/idle.c')
| -rw-r--r-- | arch/powerpc/kernel/idle.c | 25 |
1 files changed, 25 insertions, 0 deletions
diff --git a/arch/powerpc/kernel/idle.c b/arch/powerpc/kernel/idle.c index a36fd053c3db..422e31d2f5a2 100644 --- a/arch/powerpc/kernel/idle.c +++ b/arch/powerpc/kernel/idle.c @@ -77,6 +77,31 @@ void arch_cpu_idle(void) int powersave_nap; +#ifdef CONFIG_PPC_970_NAP +void power4_idle(void) +{ + if (!cpu_has_feature(CPU_FTR_CAN_NAP)) + return; + + if (!powersave_nap) + return; + + if (!prep_irq_for_idle()) + return; + + if (cpu_has_feature(CPU_FTR_ALTIVEC)) + asm volatile("DSSALL ; sync" ::: "memory"); + + power4_idle_nap(); + + /* + * power4_idle_nap returns with interrupts enabled (soft and hard). + * to our caller with interrupts enabled (soft and hard). Our caller + * can cope with either interrupts disabled or enabled upon return. + */ +} +#endif + #ifdef CONFIG_SYSCTL /* * Register the sysctl to set/clear powersave_nap. |