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-rw-r--r--arch/alpha/Kconfig24
-rw-r--r--arch/alpha/include/asm/pal.h1
-rw-r--r--arch/alpha/include/uapi/asm/pal.h1
-rw-r--r--arch/alpha/kernel/process.c17
-rw-r--r--arch/alpha/kernel/traps.c15
5 files changed, 58 insertions, 0 deletions
diff --git a/arch/alpha/Kconfig b/arch/alpha/Kconfig
index a67b971..f9e84da 100644
--- a/arch/alpha/Kconfig
+++ b/arch/alpha/Kconfig
@@ -586,6 +586,30 @@ config NUMA
Access). This option is for configuring high-end multiprocessor
server machines. If in doubt, say N.
+config ALPHA_WTINT
+ bool "Use WTINT" if ALPHA_SRM || ALPHA_GENERIC
+ default y if ALPHA_QEMU
+ default n if ALPHA_EV5 || ALPHA_EV56 || (ALPHA_EV4 && !ALPHA_LCA)
+ default n if !ALPHA_SRM && !ALPHA_GENERIC
+ default y if SMP
+ ---help---
+ The Wait for Interrupt (WTINT) PALcall attempts to place the CPU
+ to sleep until the next interrupt. This may reduce the power
+ consumed, and the heat produced by the computer. However, it has
+ the side effect of making the cycle counter unreliable as a timing
+ device across the sleep.
+
+ For emulation under QEMU, definitely say Y here, as we have other
+ mechanisms for measuring time than the cycle counter.
+
+ For EV4 (but not LCA), EV5 and EV56 systems, or for systems running
+ MILO, sleep mode is not supported so you might as well say N here.
+
+ For SMP systems we cannot use the cycle counter for timing anyway,
+ so you might as well say Y here.
+
+ If unsure, say N.
+
config NODES_SHIFT
int
default "7"
diff --git a/arch/alpha/include/asm/pal.h b/arch/alpha/include/asm/pal.h
index 6fcd2b5..e78ec9b 100644
--- a/arch/alpha/include/asm/pal.h
+++ b/arch/alpha/include/asm/pal.h
@@ -89,6 +89,7 @@ __CALL_PAL_W1(wrmces, unsigned long);
__CALL_PAL_RW2(wrperfmon, unsigned long, unsigned long, unsigned long);
__CALL_PAL_W1(wrusp, unsigned long);
__CALL_PAL_W1(wrvptptr, unsigned long);
+__CALL_PAL_RW1(wtint, unsigned long, unsigned long);
/*
* TB routines..
diff --git a/arch/alpha/include/uapi/asm/pal.h b/arch/alpha/include/uapi/asm/pal.h
index 3c0ce08..dfc8140 100644
--- a/arch/alpha/include/uapi/asm/pal.h
+++ b/arch/alpha/include/uapi/asm/pal.h
@@ -46,6 +46,7 @@
#define PAL_rdusp 58
#define PAL_whami 60
#define PAL_retsys 61
+#define PAL_wtint 62
#define PAL_rti 63
diff --git a/arch/alpha/kernel/process.c b/arch/alpha/kernel/process.c
index f2360a7..1941a07 100644
--- a/arch/alpha/kernel/process.c
+++ b/arch/alpha/kernel/process.c
@@ -46,6 +46,23 @@
void (*pm_power_off)(void) = machine_power_off;
EXPORT_SYMBOL(pm_power_off);
+#ifdef CONFIG_ALPHA_WTINT
+/*
+ * Sleep the CPU.
+ * EV6, LCA45 and QEMU know how to power down, skipping N timer interrupts.
+ */
+void arch_cpu_idle(void)
+{
+ wtint(0);
+ local_irq_enable();
+}
+
+void arch_cpu_idle_dead(void)
+{
+ wtint(INT_MAX);
+}
+#endif /* ALPHA_WTINT */
+
struct halt_info {
int mode;
char *restart_cmd;
diff --git a/arch/alpha/kernel/traps.c b/arch/alpha/kernel/traps.c
index bd0665c..9c4c189 100644
--- a/arch/alpha/kernel/traps.c
+++ b/arch/alpha/kernel/traps.c
@@ -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);
}
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