Re: [PATCH v4 2/2] ARM hibernation / suspend-to-disk

[Russ Dill]

On 02/26/2014 11:10 AM, Sebastian Capella wrote:
> From: Russ Dill <Russ.Dill@xxxxxx>
> 
> Enable hibernation for ARM architectures and provide ARM
> architecture specific calls used during hibernation.
> 
> The swsusp hibernation framework depends on the
> platform first having functional suspend/resume.
> 
> Then, in order to enable hibernation on a given platform, a
> platform_hibernation_ops structure may need to be registered with
> the system in order to save/restore any SoC-specific / cpu specific
> state needing (re)init over a suspend-to-disk/resume-from-disk cycle.
> 
> For example:
> 
>      - "secure" SoCs that have different sets of control registers
>        and/or different CR reg access patterns.
> 
>      - SoCs with L2 caches as the activation sequence there is
>        SoC-dependent; a full off-on cycle for L2 is not done
>        by the hibernation support code.
> 
>      - SoCs requiring steps on wakeup _before_ the "generic" parts
>        done by cpu_suspend / cpu_resume can work correctly.
> 
>      - SoCs having persistent state which is maintained during suspend
>        and resume, but will be lost during the power off cycle after
>        suspend-to-disk.
> 
> This is a rebase/rework of Frank Hofmann's v5 hibernation patchset.
> 
> Cc: Russ Dill <Russ.Dill@xxxxxx>
> Cc: "Rafael J. Wysocki" <rjw@xxxxxxxxxxxxx>
> Signed-off-by: Sebastian Capella <sebastian.capella@xxxxxxxxxx>
> Cc: Russell King <linux@xxxxxxxxxxxxxxxx>
> Cc: Len Brown <len.brown@xxxxxxxxx>
> Cc: Pavel Machek <pavel@xxxxxx>
> Cc: Nicolas Pitre <nico@xxxxxxxxxx>
> Cc: Santosh Shilimkar <santosh.shilimkar@xxxxxx>
> Cc: Will Deacon <will.deacon@xxxxxxx>
> Cc: Jonathan Austin <jonathan.austin@xxxxxxx>
> Cc: Catalin Marinas <catalin.marinas@xxxxxxx>
> Cc: "Uwe Kleine-KÃnig" <u.kleine-koenig@xxxxxxxxxxxxxx>
> Cc: Stephen Boyd <sboyd@xxxxxxxxxxxxxx>
> Cc: Lorenzo Pieralisi <lorenzo.pieralisi@xxxxxxx>

Acked-by: Russ Dill <russ.dill@xxxxxx>


> ---
>  arch/arm/include/asm/memory.h |    1 +
>  arch/arm/kernel/Makefile      |    1 +
>  arch/arm/kernel/hibernate.c   |  113 +++++++++++++++++++++++++++++++++++++++++
>  arch/arm/mm/Kconfig           |    5 ++
>  include/linux/suspend.h       |    2 +
>  5 files changed, 122 insertions(+)
>  create mode 100644 arch/arm/kernel/hibernate.c
> 
> diff --git a/arch/arm/include/asm/memory.h b/arch/arm/include/asm/memory.h
> index 8756e4b..1079ea8 100644
> --- a/arch/arm/include/asm/memory.h
> +++ b/arch/arm/include/asm/memory.h
> @@ -291,6 +291,7 @@ static inline void *phys_to_virt(phys_addr_t x)
>   */
>  #define __pa(x)			__virt_to_phys((unsigned long)(x))
>  #define __va(x)			((void *)__phys_to_virt((phys_addr_t)(x)))
> +#define __pa_symbol(x)		__pa(RELOC_HIDE((unsigned long)(x), 0))
>  #define pfn_to_kaddr(pfn)	__va((pfn) << PAGE_SHIFT)
>  
>  extern phys_addr_t (*arch_virt_to_idmap)(unsigned long x);
> diff --git a/arch/arm/kernel/Makefile b/arch/arm/kernel/Makefile
> index a30fc9b..8afa848 100644
> --- a/arch/arm/kernel/Makefile
> +++ b/arch/arm/kernel/Makefile
> @@ -39,6 +39,7 @@ obj-$(CONFIG_ARTHUR)		+= arthur.o
>  obj-$(CONFIG_ISA_DMA)		+= dma-isa.o
>  obj-$(CONFIG_PCI)		+= bios32.o isa.o
>  obj-$(CONFIG_ARM_CPU_SUSPEND)	+= sleep.o suspend.o
> +obj-$(CONFIG_HIBERNATION)	+= hibernate.o
>  obj-$(CONFIG_SMP)		+= smp.o
>  ifdef CONFIG_MMU
>  obj-$(CONFIG_SMP)		+= smp_tlb.o
> diff --git a/arch/arm/kernel/hibernate.c b/arch/arm/kernel/hibernate.c
> new file mode 100644
> index 0000000..70e17d2
> --- /dev/null
> +++ b/arch/arm/kernel/hibernate.c
> @@ -0,0 +1,113 @@
> +/*
> + * Hibernation support specific for ARM
> + *
> + * Derived from work on ARM hibernation support by:
> + *
> + * Ubuntu project, hibernation support for mach-dove
> + * Copyright (C) 2010 Nokia Corporation (Hiroshi Doyu)
> + * Copyright (C) 2010 Texas Instruments, Inc. (Teerth Reddy et al.)
> + *  https://lkml.org/lkml/2010/6/18/4
> + *  https://lists.linux-foundation.org/pipermail/linux-pm/2010-June/027422.html
> + *  https://patchwork.kernel.org/patch/96442/
> + *
> + * Copyright (C) 2006 Rafael J. Wysocki <rjw@xxxxxxx>
> + *
> + * License terms: GNU General Public License (GPL) version 2
> + */
> +
> +#include <linux/mm.h>
> +#include <linux/suspend.h>
> +#include <asm/tlbflush.h>
> +#include <asm/cacheflush.h>
> +#include <asm/system_misc.h>
> +#include <asm/idmap.h>
> +#include <asm/suspend.h>
> +
> +extern const void __nosave_begin, __nosave_end;
> +
> +int pfn_is_nosave(unsigned long pfn)
> +{
> +	unsigned long nosave_begin_pfn =
> +			__pa_symbol(&__nosave_begin) >> PAGE_SHIFT;
> +	unsigned long nosave_end_pfn =
> +			PAGE_ALIGN(__pa_symbol(&__nosave_end)) >> PAGE_SHIFT;
> +
> +	return (pfn >= nosave_begin_pfn) && (pfn < nosave_end_pfn);
> +}
> +
> +void notrace save_processor_state(void)
> +{
> +	WARN_ON(num_online_cpus() != 1);
> +	local_fiq_disable();
> +}
> +
> +void notrace restore_processor_state(void)
> +{
> +	local_fiq_enable();
> +}
> +
> +/*
> + * Snapshot kernel memory and reset the system.
> + *
> + * swsusp_save() is executed in the suspend finisher so that the CPU
> + * context pointer and memory are part of the saved image, which is
> + * required by the resume kernel image to restart execution from
> + * swsusp_arch_suspend().
> + *
> + * soft_restart is not technically needed, but is used to get success
> + * returned from cpu_suspend.
> + * 
> + * When soft reboot completes, the hibernation snapshot is written out.
> + */
> +static int notrace __swsusp_arch_save_image(unsigned long unused)
> +{
> +	int ret;
> +
> +	ret = swsusp_save();
> +	if (ret == 0)
> +		soft_restart(virt_to_phys(cpu_resume));
> +	return ret;
> +}
> +
> +/*
> + * Save the current CPU state before suspend / poweroff.
> + */
> +int notrace swsusp_arch_suspend(void)
> +{
> +	return cpu_suspend(0, __swsusp_arch_save_image);
> +}
> +
> +/*
> + * The framework loads the hibernation image into a linked list anchored
> + * at restore_pblist, for swsusp_arch_resume() to copy back to the proper
> + * destinations.
> + *
> + * To make this work if resume is triggered from initramfs, the
> + * pagetables need to be switched to allow writes to kernel mem.
> + */
> +static void notrace __swsusp_arch_restore_image(void *unused)
> +{
> +	struct pbe *pbe;
> +
> +	cpu_switch_mm(idmap_pgd, &init_mm);
> +	for (pbe = restore_pblist; pbe; pbe = pbe->next)
> +		copy_page(pbe->orig_address, pbe->address);
> +
> +	soft_restart(virt_to_phys(cpu_resume));
> +}
> +
> +static u8 __swsusp_resume_stk[PAGE_SIZE/2] __nosavedata;
> +
> +/*
> + * Resume from the hibernation image.
> + * Due to the kernel heap / data restore, stack contents change underneath
> + * and that would make function calls impossible; switch to a temporary
> + * stack within the nosave region to avoid that problem.
> + */
> +int swsusp_arch_resume(void)
> +{
> +	extern void call_with_stack(void (*fn)(void *), void *arg, void *sp);
> +	call_with_stack(__swsusp_arch_restore_image, 0,
> +		__swsusp_resume_stk + sizeof(__swsusp_resume_stk));
> +	return 0;
> +}
> diff --git a/arch/arm/mm/Kconfig b/arch/arm/mm/Kconfig
> index 1f8fed9..83707702 100644
> --- a/arch/arm/mm/Kconfig
> +++ b/arch/arm/mm/Kconfig
> @@ -611,6 +611,11 @@ config CPU_USE_DOMAINS
>  config IO_36
>  	bool
>  
> +config ARCH_HIBERNATION_POSSIBLE
> +	bool
> +	depends on MMU
> +	default y if CPU_ARM920T || CPU_ARM926T || CPU_SA1100 || CPU_XSCALE || CPU_XSC3 || CPU_V6 || CPU_V6K || CPU_V7
> +
>  comment "Processor Features"
>  
>  config ARM_LPAE
> diff --git a/include/linux/suspend.h b/include/linux/suspend.h
> index f73cabf..38bbf95 100644
> --- a/include/linux/suspend.h
> +++ b/include/linux/suspend.h
> @@ -320,6 +320,8 @@ extern unsigned long get_safe_page(gfp_t gfp_mask);
>  extern void hibernation_set_ops(const struct platform_hibernation_ops *ops);
>  extern int hibernate(void);
>  extern bool system_entering_hibernation(void);
> +asmlinkage int swsusp_save(void);
> +extern struct pbe *restore_pblist;
>  #else /* CONFIG_HIBERNATION */
>  static inline void register_nosave_region(unsigned long b, unsigned long e) {}
>  static inline void register_nosave_region_late(unsigned long b, unsigned long e) {}
> 

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