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 <npig...@gmail.com>
---
arch/powerpc/include/asm/processor.h | 3 +
arch/powerpc/kernel/Makefile | 3 +-
arch/powerpc/kernel/exceptions-64s.S | 9 ---
arch/powerpc/kernel/idle.c | 25 ++++++++
arch/powerpc/kernel/idle_book3s.S | 35 +++++++++++
arch/powerpc/kernel/idle_power4.S | 87 ----------------------------
arch/powerpc/platforms/Kconfig | 4 ++
7 files changed, 68 insertions(+), 98 deletions(-)
delete mode 100644 arch/powerpc/kernel/idle_power4.S
diff --git a/arch/powerpc/include/asm/processor.h
b/arch/powerpc/include/asm/processor.h
index 706ac5df546f..c0d870c57061 100644
--- a/arch/powerpc/include/asm/processor.h
+++ b/arch/powerpc/include/asm/processor.h
@@ -418,6 +418,9 @@ static inline unsigned long get_clean_sp(unsigned long sp,
int is_32)
extern unsigned long isa300_idle_stop_noloss(unsigned long psscr_val);
extern unsigned long isa300_idle_stop_mayloss(unsigned long psscr_val);
extern unsigned long isa206_idle_insn_mayloss(unsigned long type);
+#ifdef CONFIG_PPC_970_NAP
+extern void power4_idle_nap(void);
+#endif
extern unsigned long cpuidle_disable;
enum idle_boot_override {IDLE_NO_OVERRIDE = 0, IDLE_POWERSAVE_OFF};
diff --git a/arch/powerpc/kernel/Makefile b/arch/powerpc/kernel/Makefile
index 56dfa7a2a6f2..04c6d8cc241b 100644
--- a/arch/powerpc/kernel/Makefile
+++ b/arch/powerpc/kernel/Makefile
@@ -64,8 +64,7 @@ obj-$(CONFIG_PPC_BOOK3E_64) += exceptions-64e.o
idle_book3e.o
obj-$(CONFIG_PPC_BARRIER_NOSPEC) += security.o
obj-$(CONFIG_PPC64) += vdso64/
obj-$(CONFIG_ALTIVEC) += vecemu.o
-obj-$(CONFIG_PPC_970_NAP) += idle_power4.o
-obj-$(CONFIG_PPC_P7_NAP) += idle_book3s.o
+obj-$(CONFIG_PPC_BOOK3S_IDLE) += idle_book3s.o
procfs-y := proc_powerpc.o
obj-$(CONFIG_PROC_FS) += $(procfs-y)
rtaspci-$(CONFIG_PPC64)-$(CONFIG_PCI) := rtas_pci.o
diff --git a/arch/powerpc/kernel/exceptions-64s.S
b/arch/powerpc/kernel/exceptions-64s.S
index eee5bef736c8..64d5ffbb07d1 100644
--- a/arch/powerpc/kernel/exceptions-64s.S
+++ b/arch/powerpc/kernel/exceptions-64s.S
@@ -2286,15 +2286,6 @@ USE_FIXED_SECTION(virt_trampolines)
__end_interrupts:
DEFINE_FIXED_SYMBOL(__end_interrupts)
-#ifdef CONFIG_PPC_970_NAP
-EXC_COMMON_BEGIN(power4_fixup_nap)
- andc r9,r9,r10
- std r9,TI_LOCAL_FLAGS(r11)
- ld r10,_LINK(r1) /* make idle task do the */
- std r10,_NIP(r1) /* equivalent of a blr */
- blr
-#endif
-
CLOSE_FIXED_SECTION(real_vectors);
CLOSE_FIXED_SECTION(real_trampolines);
CLOSE_FIXED_SECTION(virt_vectors);
diff --git a/arch/powerpc/kernel/idle.c b/arch/powerpc/kernel/idle.c
index d7216c9abda1..605defde43b9 100644
--- a/arch/powerpc/kernel/idle.c
+++ b/arch/powerpc/kernel/idle.c
@@ -81,6 +81,31 @@ 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.
diff --git a/arch/powerpc/kernel/idle_book3s.S
b/arch/powerpc/kernel/idle_book3s.S
index 2dfbd5d5b932..5afac9177fec 100644
--- a/arch/powerpc/kernel/idle_book3s.S
+++ b/arch/powerpc/kernel/idle_book3s.S
@@ -19,7 +19,9 @@
#include <asm/asm-offsets.h>
#include <asm/ppc-opcode.h>
#include <asm/cpuidle.h>
+#include <asm/thread_info.h> /* TLF_NAPPING */
+#ifdef CONFIG_PPC_P7_NAP
/*
* Desired PSSCR in r3
*
@@ -185,4 +187,37 @@ _GLOBAL(isa206_idle_insn_mayloss)
bne 2f
IDLE_STATE_ENTER_SEQ_NORET(PPC_SLEEP)
2: IDLE_STATE_ENTER_SEQ_NORET(PPC_WINKLE)
+#endif
+#ifdef CONFIG_PPC_970_NAP
+_GLOBAL(power4_idle_nap)
+ LOAD_REG_IMMEDIATE(r7, MSR_KERNEL|MSR_EE|MSR_POW)
+ ld r9,PACA_THREAD_INFO(r13)
+ ld r8,TI_LOCAL_FLAGS(r9)
+ ori r8,r8,_TLF_NAPPING
+ std r8,TI_LOCAL_FLAGS(r9)
+ /*
+ * NAPPING bit is set, from this point onward power4_fixup_nap
+ * will cause exceptions to return to power4_idle_nap_return.
+ */
+1: sync
+ isync
+ mtmsrd r7
+ isync
+ b 1b
+power4_idle_nap_return:
+ blr
+
+ /*
+ * Called by exception entry code if _TLF_NAPPING was set, this clear
+ * the NAPPING flag, and redirects the exception exit to
+ * power4_fixup_nap_return.
+ */
+ .globl power4_fixup_nap
+power4_fixup_nap:
+ andc r9,r9,r10
+ std r9,TI_LOCAL_FLAGS(r11)
+ LOAD_REG_ADDR(r10, power4_idle_nap_return)
+ std r10,_NIP(r1)
+ blr
+#endif
diff --git a/arch/powerpc/kernel/idle_power4.S
b/arch/powerpc/kernel/idle_power4.S
deleted file mode 100644
index a2fdb0a34b75..000000000000
--- a/arch/powerpc/kernel/idle_power4.S
+++ /dev/null
@@ -1,87 +0,0 @@
-/*
- * This file contains the power_save function for 970-family CPUs.
- *
- * This program is free software; you can redistribute it and/or
- * modify it under the terms of the GNU General Public License
- * as published by the Free Software Foundation; either version
- * 2 of the License, or (at your option) any later version.
- */
-
-#include <linux/threads.h>
-#include <asm/processor.h>
-#include <asm/page.h>
-#include <asm/cputable.h>
-#include <asm/thread_info.h>
-#include <asm/ppc_asm.h>
-#include <asm/asm-offsets.h>
-#include <asm/irqflags.h>
-#include <asm/hw_irq.h>
-#include <asm/feature-fixups.h>
-
-#undef DEBUG
-
- .text
-
-_GLOBAL(power4_idle)
-BEGIN_FTR_SECTION
- blr
-END_FTR_SECTION_IFCLR(CPU_FTR_CAN_NAP)
- /* Now check if user or arch enabled NAP mode */
- LOAD_REG_ADDRBASE(r3,powersave_nap)
- lwz r4,ADDROFF(powersave_nap)(r3)
- cmpwi 0,r4,0
- beqlr
-
- /* This sequence is similar to prep_irq_for_idle() */
-
- /* Hard disable interrupts */
- mfmsr r7
- rldicl r0,r7,48,1
- rotldi r0,r0,16
- mtmsrd r0,1
-
- /* Check if something happened while soft-disabled */
- lbz r0,PACAIRQHAPPENED(r13)
- cmpwi cr0,r0,0
- bne- 2f
-
- /*
- * Soft-enable interrupts. This will make power4_fixup_nap return
- * to our caller with interrupts enabled (soft and hard). The caller
- * can cope with either interrupts disabled or enabled upon return.
- */
-#ifdef CONFIG_TRACE_IRQFLAGS
- /* Tell the tracer interrupts are on, because idle responds to them. */
- mflr r0
- std r0,16(r1)
- stdu r1,-128(r1)
- bl trace_hardirqs_on
- addi r1,r1,128
- ld r0,16(r1)
- mtlr r0
- mfmsr r7
-#endif /* CONFIG_TRACE_IRQFLAGS */
-
- li r0,IRQS_ENABLED
- stb r0,PACAIRQSOFTMASK(r13) /* we'll hard-enable shortly */
-BEGIN_FTR_SECTION
- DSSALL
- sync
-END_FTR_SECTION_IFSET(CPU_FTR_ALTIVEC)
- ld r9, PACA_THREAD_INFO(r13)
- ld r8,TI_LOCAL_FLAGS(r9) /* set napping bit */
- ori r8,r8,_TLF_NAPPING /* so when we take an exception */
- std r8,TI_LOCAL_FLAGS(r9) /* it will return to our caller */
- ori r7,r7,MSR_EE
- oris r7,r7,MSR_POW@h
-1: sync
- isync
- mtmsrd r7
- isync
- b 1b
-
-2: /* Return if an interrupt had happened while soft disabled */
- /* Set the HARD_DIS flag because interrupts are now hard disabled */
- ori r0,r0,PACA_IRQ_HARD_DIS
- stb r0,PACAIRQHAPPENED(r13)
- blr
diff --git a/arch/powerpc/platforms/Kconfig b/arch/powerpc/platforms/Kconfig
index f3fb79fccc72..736325451bc4 100644
--- a/arch/powerpc/platforms/Kconfig
+++ b/arch/powerpc/platforms/Kconfig
@@ -177,6 +177,10 @@ config PPC_970_NAP
config PPC_P7_NAP
bool
+config PPC_BOOK3S_IDLE
+ def_bool y
+ depends on (PPC_970_NAP || PPC_P7_NAP)
+
config PPC_INDIRECT_PIO
bool
select GENERIC_IOMAP
--
2.20.1
