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    Subject[PATCH v6 2/2] ARM hibernation / suspend-to-disk
    Date
    From: Russ Dill <Russ.Dill@ti.com>

    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.

    Acked-by: Russ Dill <Russ.Dill@ti.com>
    Cc: "Rafael J. Wysocki" <rjw@rjwysocki.net>
    Signed-off-by: Sebastian Capella <sebastian.capella@linaro.org>
    Acked-by: Pavel Machek <pavel@ucw.cz>
    Cc: Russell King <linux@arm.linux.org.uk>
    Cc: Len Brown <len.brown@intel.com>
    Cc: Nicolas Pitre <nico@linaro.org>
    Cc: Santosh Shilimkar <santosh.shilimkar@ti.com>
    Cc: Will Deacon <will.deacon@arm.com>
    Cc: Jonathan Austin <jonathan.austin@arm.com>
    Cc: Catalin Marinas <catalin.marinas@arm.com>
    Cc: "Uwe Kleine-König" <u.kleine-koenig@pengutronix.de>
    Cc: Stephen Boyd <sboyd@codeaurora.org>
    Cc: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
    ---
    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..a41e0e3
    --- /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@sisk.pl>
    + *
    + * 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 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, 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 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 resume_stack[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(arch_restore_image, 0,
    + resume_stack + sizeof(resume_stack));
    + 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) {}
    --
    1.7.9.5
    --
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