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arm64: kernel: suspend/resume registers save/restore

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Power management software requires the kernel to save and restore
CPU registers while going through suspend and resume operations
triggered by kernel subsystems like CPU idle and suspend to RAM.

This patch implements code that provides save and restore mechanism
for the arm v8 implementation. Memory for the context is passed as
parameter to both cpu_do_suspend and cpu_do_resume functions, and allows
the callers to implement context allocation as they deem fit.

The registers that are saved and restored correspond to the registers set
actually required by the kernel to be up and running which represents a
subset of v8 ISA.

Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
This commit is contained in:
Lorenzo Pieralisi 2013-07-17 10:14:45 +01:00
parent 976d7d3f79
commit 6732bc65c2
3 changed files with 90 additions and 0 deletions
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3
arch/arm64/include/asm/proc-fns.h
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@ -26,11 +26,14 @@
#include <asm/page.h>
struct mm_struct;
struct cpu_suspend_ctx;
extern void cpu_cache_off(void);
extern void cpu_do_idle(void);
extern void cpu_do_switch_mm(unsigned long pgd_phys, struct mm_struct *mm);
extern void cpu_reset(unsigned long addr) __attribute__((noreturn));
extern void cpu_do_suspend(struct cpu_suspend_ctx *ptr);
extern u64 cpu_do_resume(phys_addr_t ptr, u64 idmap_ttbr);
#include <asm/memory.h>

18
arch/arm64/include/asm/suspend.h Normal file
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@ -0,0 +1,18 @@
#ifndef __ASM_SUSPEND_H
#define __ASM_SUSPEND_H
#define NR_CTX_REGS 11
/*
* struct cpu_suspend_ctx must be 16-byte aligned since it is allocated on
* the stack, which must be 16-byte aligned on v8
*/
struct cpu_suspend_ctx {
/*
* This struct must be kept in sync with
* cpu_do_{suspend/resume} in mm/proc.S
*/
u64 ctx_regs[NR_CTX_REGS];
u64 sp;
} __aligned(16);
#endif

69
arch/arm64/mm/proc.S
View File

@ -80,6 +80,75 @@ ENTRY(cpu_do_idle)
ret
ENDPROC(cpu_do_idle)
#ifdef CONFIG_ARM64_CPU_SUSPEND
/**
* cpu_do_suspend - save CPU registers context
*
* x0: virtual address of context pointer
*/
ENTRY(cpu_do_suspend)
mrs x2, tpidr_el0
mrs x3, tpidrro_el0
mrs x4, contextidr_el1
mrs x5, mair_el1
mrs x6, cpacr_el1
mrs x7, ttbr1_el1
mrs x8, tcr_el1
mrs x9, vbar_el1
mrs x10, mdscr_el1
mrs x11, oslsr_el1
mrs x12, sctlr_el1
stp x2, x3, [x0]
stp x4, x5, [x0, #16]
stp x6, x7, [x0, #32]
stp x8, x9, [x0, #48]
stp x10, x11, [x0, #64]
str x12, [x0, #80]
ret
ENDPROC(cpu_do_suspend)
/**
* cpu_do_resume - restore CPU register context
*
* x0: Physical address of context pointer
* x1: ttbr0_el1 to be restored
*
* Returns:
* sctlr_el1 value in x0
*/
ENTRY(cpu_do_resume)
/*
* Invalidate local tlb entries before turning on MMU
*/
tlbi vmalle1
ldp x2, x3, [x0]
ldp x4, x5, [x0, #16]
ldp x6, x7, [x0, #32]
ldp x8, x9, [x0, #48]
ldp x10, x11, [x0, #64]
ldr x12, [x0, #80]
msr tpidr_el0, x2
msr tpidrro_el0, x3
msr contextidr_el1, x4
msr mair_el1, x5
msr cpacr_el1, x6
msr ttbr0_el1, x1
msr ttbr1_el1, x7
msr tcr_el1, x8
msr vbar_el1, x9
msr mdscr_el1, x10
/*
* Restore oslsr_el1 by writing oslar_el1
*/
ubfx x11, x11, #1, #1
msr oslar_el1, x11
mov x0, x12
dsb nsh // Make sure local tlb invalidation completed
isb
ret
ENDPROC(cpu_do_resume)
#endif
/*
* cpu_switch_mm(pgd_phys, tsk)
*