powerpc: Add NAP mode support on Power7 in HV mode

Wakeup comes from the system reset handler with a potential loss of
the non-hypervisor CPU state. We save the non-volatile state on the
stack and a pointer to it in the PACA, which the system reset handler
uses to restore things

Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

1 files changed, 97 insertions, 0 deletions

diff --git a/arch/powerpc/kernel/idle_power7.S b/arch/powerpc/kernel/idle_power7.S
new file mode 100644
index 000000000000..f8f0bc7f1d4f
--- /dev/null
+++ b/arch/powerpc/kernel/idle_power7.S
@@ -0,0 +1,97 @@
+/*
+ *  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/ppc-opcode.h>
+
+#undef DEBUG
+
+	.text
+
+_GLOBAL(power7_idle)
+	/* 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
+
+	/* NAP is a state loss, we create a regs frame on the
+	 * stack, fill it up with the state we care about and
+	 * stick a pointer to it in PACAR1. We really only
+	 * need to save PC, some CR bits and the NV GPRs,
+	 * but for now an interrupt frame will do.
+	 */
+	mflr	r0
+	std	r0,16(r1)
+	stdu	r1,-INT_FRAME_SIZE(r1)
+	std	r0,_LINK(r1)
+	std	r0,_NIP(r1)
+
+#ifndef CONFIG_SMP
+	/* Make sure FPU, VSX etc... are flushed as we may lose
+	 * state when going to nap mode
+	 */
+	bl	.discard_lazy_cpu_state
+#endif /* CONFIG_SMP */
+
+	/* Hard disable interrupts */
+	mfmsr	r9
+	rldicl	r9,r9,48,1
+	rotldi	r9,r9,16
+	mtmsrd	r9,1			/* hard-disable interrupts */
+	li	r0,0
+	stb	r0,PACASOFTIRQEN(r13)	/* we'll hard-enable shortly */
+	stb	r0,PACAHARDIRQEN(r13)
+
+	/* Continue saving state */
+	SAVE_GPR(2, r1)
+	SAVE_NVGPRS(r1)
+	mfcr	r3
+	std	r3,_CCR(r1)
+	std	r9,_MSR(r1)
+	std	r1,PACAR1(r13)
+
+	/* Magic NAP mode enter sequence */
+	std	r0,0(r1)
+	ptesync
+	ld	r0,0(r1)
+1:	cmp	cr0,r0,r0
+	bne	1b
+	PPC_NAP
+	b	.
+
+_GLOBAL(power7_wakeup_loss)
+	GET_PACA(r13)
+	ld	r1,PACAR1(r13)
+	REST_NVGPRS(r1)
+	REST_GPR(2, r1)
+	ld	r3,_CCR(r1)
+	ld	r4,_MSR(r1)
+	ld	r5,_NIP(r1)
+	addi	r1,r1,INT_FRAME_SIZE
+	mtcr	r3
+	mtspr	SPRN_SRR1,r4
+	mtspr	SPRN_SRR0,r5
+	rfid
+
+_GLOBAL(power7_wakeup_noloss)
+	GET_PACA(r13)
+	ld	r1,PACAR1(r13)
+	ld	r4,_MSR(r1)
+	ld	r5,_NIP(r1)
+	addi	r1,r1,INT_FRAME_SIZE
+	mtspr	SPRN_SRR1,r4
+	mtspr	SPRN_SRR0,r5
+	rfid