On Thu, May 19, 2011 at 06:31:28PM +0100, Frank Hofmann wrote: > Hi, > > /me again ... > > Sorry that this took a little ... holidays. And work. And distractions... > > Anyway, here we go again, basic code to enable hibernation > (suspend-to-disk) on ARM platforms. > > Any comments highly welcome. > > > > To use this, you need sleep.S modifications for your SoC type (to > get __save/__restore_processor_state hooks). I've sent some of those > for illustration earlier, they haven't changed, I've not included > them here, so pick these changes up from: > > http://68.183.106.108/lists/linux-pm/msg24020.html > > The patch below only contains the _generic_ code. > > > This is tested on S5P6450 and OMAP3, with the sleep...S changes just > mentioned - check the archives for those. Works both with normal > swsusp and tuxonice (again, check the archives for the TOI > modification needed). > > > > Previously, I've reported OMAP3 video issues, after > resume-from-disk. That isn't fully solved (it's a driver issue) but > I've found a workaround: Trigger the resume from initramfs, after > loading a logo image into the framebuffer and switching it on. That > gets everything back without corruptions / wrong LCD > reinitialization. > > The OMAP video seems a bit of a diva; I've got one board type on > which suspend/resume work perfectly but the omapdss driver spits out > thousands of error interrupts during system startup (before the > image is loaded), and the other board where all that is fine but the > restore somehow garbles the LCD clocking (but the driver's sysfs > files claim it's the same). > > > In short: This stuff really works now, for all I can say. And adding > support for new type of ARM SoC doesn't touch the basic / generic > code at all anymore either. > > > > > Anyway ... > About the patch, changes vs. all previous suggestions: > > * Made the assembly sources as small as I responsibly could ;-) > They compile for thumb2 (but I haven't tested that yet) as well. > > * The page copy loop is now a C function. That also has the advantage > that one can use cpu_switch_mm() - a macro - there for swapper_pg_dir, > which makes resume via uswsusp ioctl or /sys/power/tuxonice/do_resume > possible (only tested the latter, though). > > * The SoC state save/restore is made to (re-)use the existing code in > sleep....S for the particular chip. > OMAP3 and S5P64xx are provided as examples of that. > > * The save/restore_processor_state() hooks are now used in the same way > as e.g. existing powerpc code uses them (to trigger lazy saves before > and perform cache flushes after). > > > Things that probably aren't perfect yet: > > * The code currently reserves a full page for the saved "core" state. > This is more than absolutely necessary; anyone think it's a problem ? > > * it sets aside another half a page of __nosavedata page for use as > temporary stack during the image copy (so that funcs can be called). > > Right now on ARM, that's not an issue because even with TuxOnIce in, > there's less than 20 bytes of nosave stuff, so can as well put the > rest of that page to good use ;-) > > * I'd love to get rid of the include/asm-generic/vmlinux.lds.h change, > as it seems that's not necessary in other architectures. > Without that, the code gives a link error when building vmlinux > though, and I'm unsure how to address that. > > * The "integration" with the CPU sleep code is rather "backdoorish". > While the hooks into ..._cpu_suspend aren't massive, and there's no > code duplication, it'd be nicer to eventually have a cleaner way. > > * An OMAPDSS restore troubleshooting HOWTO would be helpful ;-) > > > * The patch needs to be rebaselined against a current kernel; > any preferences which tree to base this on ? > > > > Thanks for all help with the little nits ! > FrankH. > arch/arm/Kconfig | 3 + > arch/arm/include/asm/memory.h | 1 + > arch/arm/include/asm/suspend.h | 6 ++ > arch/arm/kernel/cpu.c | 65 ++++++++++++++++++++++++++ > arch/arm/kernel/swsusp.S | 92 +++++++++++++++++++++++++++++++++++++ > arch/arm/kernel/vmlinux.lds.S | 3 +- > include/asm-generic/vmlinux.lds.h | 2 +- > 7 files changed, 170 insertions(+), 2 deletions(-) > > diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig > index 6b6786c..859dd86 100644 > --- a/arch/arm/Kconfig > +++ b/arch/arm/Kconfig > @@ -198,6 +198,9 @@ config VECTORS_BASE > config ARCH_HAS_CPU_IDLE_WAIT > def_bool y > > +config ARCH_HIBERNATION_POSSIBLE > + def_bool n > + > source "init/Kconfig" > > source "kernel/Kconfig.freezer" > diff --git a/arch/arm/include/asm/memory.h b/arch/arm/include/asm/memory.h > index 5421d82..23e93a6 100644 > --- a/arch/arm/include/asm/memory.h > +++ b/arch/arm/include/asm/memory.h > @@ -191,6 +191,7 @@ static inline void *phys_to_virt(unsigned long x) > */ > #define __pa(x) __virt_to_phys((unsigned long)(x)) > #define __va(x) ((void *)__phys_to_virt((unsigned long)(x))) > +#define __pa_symbol(x) __pa(RELOC_HIDE((unsigned long)(x),0)) > #define pfn_to_kaddr(pfn) __va((pfn) << PAGE_SHIFT) > > /* > diff --git a/arch/arm/include/asm/suspend.h b/arch/arm/include/asm/suspend.h > new file mode 100644 > index 0000000..7ab1fd2 > --- /dev/null > +++ b/arch/arm/include/asm/suspend.h > @@ -0,0 +1,6 @@ > +#ifndef __ASM_ARM_SUSPEND_H > +#define __ASM_ARM_SUSPEND_H > + > +static inline int arch_prepare_suspend(void) { return 0; } > + > +#endif /* __ASM_ARM_SUSPEND_H */ > diff --git a/arch/arm/kernel/cpu.c b/arch/arm/kernel/cpu.c > new file mode 100644 > index 0000000..764c8fa > --- /dev/null > +++ b/arch/arm/kernel/cpu.c > @@ -0,0 +1,65 @@ > +/* > + * 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/sched.h> > +#include <linux/suspend.h> > +#include <asm/tlbflush.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 save_processor_state(void) > +{ > + flush_thread(); > +} > + > +void restore_processor_state(void) > +{ > + local_flush_tlb_all(); > +} > + > +u8 __swsusp_arch_ctx[PAGE_SIZE] __attribute__((aligned(PAGE_SIZE))); > +u8 __swsusp_resume_stk[PAGE_SIZE/2] __nosavedata; > + > +/* > + * The framework loads the hibernation image into this linked list, > + * 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. > + */ > +void notrace __swsusp_arch_restore_prepare(void) > +{ > + cpu_switch_mm(__virt_to_phys(swapper_pg_dir), current->active_mm); > +} > + > +void notrace __swsusp_arch_restore_image(void) > +{ > + extern struct pbe *restore_pblist; > + struct pbe *pbe; > + > + for (pbe = restore_pblist; pbe; pbe = pbe->next) > + copy_page(pbe->orig_address, pbe->address); > +} > diff --git a/arch/arm/kernel/swsusp.S b/arch/arm/kernel/swsusp.S > new file mode 100644 > index 0000000..fb260a7 > --- /dev/null > +++ b/arch/arm/kernel/swsusp.S > @@ -0,0 +1,92 @@ > +/* > + * Hibernation support specific for ARM > + * > + * Based on work 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/linkage.h> > +#include <asm/memory.h> > +#include <asm/page.h> > +#include <asm/cache.h> > +#include <asm/ptrace.h> > + > +/* > + * Save the current CPU state before suspend / poweroff. > + */ > +ENTRY(swsusp_arch_suspend) > + ldr r0, =__swsusp_arch_ctx > + mrs r1, cpsr > + str r1, [r0], #4 /* CPSR */ > +ARM( msr cpsr_c, #SYSTEM_MODE ) > +THUMB( mov r2, #SYSTEM_MODE ) > +THUMB( msr cpsr_c, r2 ) For Thumb-2 kernels, you can use the cps instruction to change the CPU mode: cps #SYSTEM_MODE For ARM though, this instruction is only supported for ARMv6 and above, so it's best to keep the msr form for compatibility for that case. > + stm r0!, {r4-r12,lr} /* nonvolatile regs */ Since r12 is allowed to be corrupted across a function call, we probably don't need to save it. > + str sp, [r0], #4 > +ARM( msr cpsr_c, #SVC_MODE ) > +THUMB( mov r2, #SVC_MODE ) > +THUMB( msr cpsr_c, r2 ) > + mrs r2, spsr > + stm r0!, {r2,lr} /* SVC SPSR, SVC regs */ > + str sp, [r0], #4 > + msr cpsr, r1 /* restore mode at entry */ > + push {lr} > + bl __save_processor_state <aside> Structurally, we seem to have: swsusp_arch_suspend { /* save some processor state */ __save_processor_state(); swsusp_save(); } Is __save_processor_state() intended to encapsulate all the CPU-model- specific state saving? Excuse my ignorance of previous conversations... </aside> > + pop {lr} > + b swsusp_save > +ENDPROC(swsusp_arch_suspend) I'm not too familiar with the suspend/resume stuff, so I may be asking a dumb question here, but: Where do we save/restore r8_FIQ..r13_FIQ, r13_IRQ, r13_UND and r13_ABT? (I'm assuming there's no reason to save/restore r14 or SPSR for any exception mode, since we presumably aren't going to suspend/resume from inside an exception handler (?)) The exception stack pointers might conceivably be reinitialised to sane values on resume, without necessarily needing to save/restore them, providing my assumption in the previous paragraph is correct. r8_FIQ..r12_FIQ can store arbitrary state used by the FIQ handler, if FIQ is in use. Can we expect any driver using FIQ to save/restore this state itself, rather than doing it globally? This may be reasonable. Cheers ---Dave _______________________________________________ linux-pm mailing list linux-pm@xxxxxxxxxxxxxxxxxxxxxxxxxx https://lists.linux-foundation.org/mailman/listinfo/linux-pm
