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alpha: Primitive support for CPU power down.

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Use WTINT to wait for the next interrupt.  Squash the WTINT call
if the PALcode doesn't support it (e.g. MILO).  No attempt is yet
made to skip clock ticks during normal scheduling in order to stay
in power down mode longer.

Signed-off-by: Richard Henderson <rth@twiddle.net>
This commit is contained in:
Richard Henderson
2013-07-12 09:36:21 -07:00
committed by Matt Turner
parent fddd87d6e1
commit 7f3bbb82e0
5 changed files with 58 additions and 0 deletions
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15
arch/alpha/kernel/traps.c
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@@ -241,6 +241,21 @@ do_entIF(unsigned long type, struct pt_regs *regs)
(const char *)(data[1] | (long)data[2] << 32),
data[0]);
}
#ifdef CONFIG_ALPHA_WTINT
if (type == 4) {
/* If CALL_PAL WTINT is totally unsupported by the
PALcode, e.g. MILO, "emulate" it by overwriting
the insn. */
unsigned int *pinsn
= (unsigned int *) regs->pc - 1;
if (*pinsn == PAL_wtint) {
*pinsn = 0x47e01400; /* mov 0,$0 */
imb();
regs->r0 = 0;
return;
}
}
#endif /* ALPHA_WTINT */
die_if_kernel((type == 1 ? "Kernel Bug" : "Instruction fault"),
regs, type, NULL);
}