[RFC PATCH v3] ARM hibernation/suspend-to-disk support

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Hi,

I've cleaned this up by the suggestions in the previous thread; this is the result.

- now baselined against rmk/devel-stable
- didn't create the <asm/suspend.h> because Rafael is just removing
  that everywhere anyway
- Fixes re prev suggestion:
	local_fiq_enable/disable bracketing
	save only absolutely essential regs and let cpu_init do the rest
	thumb2 clean assembly
	allows mach hooks (but they're not defined by this code)

- Also: uses the "generic suspend/resume support" code
  (commit f6b0fa02e8b0708d17d631afce456524eadf87ff, rmk/devel-stable)

Via the latter, the previously-used hooks into machine-dependent code, __save/__restore_processor_state, have become unnecessary.

This now simply calls the cpu_do_suspend/resume utilities provided by the generic code.


I'm still figuring out how to best test a recent devel-stable kernel ...


Please let me know what you think,
Thanks in advance,

FrankH.


==============================================================================
Note on non-current kernels (older than 2.6.38):
==============================================================================
The use of generic CPU suspend/resume also ties the code to a sufficiently-recent kernel - it requires the code from:

http://ftp.arm.linux.org.uk/git/gitweb.cgi?p=linux-2.6-arm.git;a=commitdiff;h=f6b0fa02e8b0708d17d631afce456524eadf87ff

Which is, for many that (want to) use the feature, a hurdle...

If you're using an older kernel (2.6.37 or below), try the "generic" part posted via:

https://patchwork.kernel.org/patch/809212/

and add a __save/__restore_processor_state for your CPU type, as mentioned here:

http://lists.arm.linux.org.uk/lurker/message/20110520.123937.760c528f.en.html
==============================================================================
 arch/arm/include/asm/memory.h |    1 +
 arch/arm/kernel/Makefile      |    1 +
 arch/arm/kernel/cpu.c         |   70 +++++++++++++++++++++++++++++++++
 arch/arm/kernel/swsusp.S      |   87 +++++++++++++++++++++++++++++++++++++++++
 arch/arm/mm/Kconfig           |    5 ++
 5 files changed, 164 insertions(+), 0 deletions(-)

diff --git a/arch/arm/include/asm/memory.h b/arch/arm/include/asm/memory.h
index 431077c..c7ef454 100644
--- a/arch/arm/include/asm/memory.h
+++ b/arch/arm/include/asm/memory.h
@@ -250,6 +250,7 @@ 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((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/kernel/Makefile b/arch/arm/kernel/Makefile
index 8d95446..b76a403 100644
--- a/arch/arm/kernel/Makefile
+++ b/arch/arm/kernel/Makefile
@@ -30,6 +30,7 @@ obj-$(CONFIG_ARTHUR)		+= arthur.o
 obj-$(CONFIG_ISA_DMA)		+= dma-isa.o
 obj-$(CONFIG_PCI)		+= bios32.o isa.o
 obj-$(CONFIG_PM_SLEEP)		+= sleep.o
+obj-$(CONFIG_HIBERNATION)	+= cpu.o swsusp.o
 obj-$(CONFIG_HAVE_SCHED_CLOCK)	+= sched_clock.o
 obj-$(CONFIG_SMP)		+= smp.o smp_tlb.o
 obj-$(CONFIG_HAVE_ARM_SCU)	+= smp_scu.o
diff --git a/arch/arm/kernel/cpu.c b/arch/arm/kernel/cpu.c
new file mode 100644
index 0000000..2dfb40b
--- /dev/null
+++ b/arch/arm/kernel/cpu.c
@@ -0,0 +1,70 @@
+/*
+ * 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();
+	local_fiq_disable();
+#ifdef CONFIG_ARM_MACH_HIBERNATION_HOOK
+	mach_save_state();
+#endif
+}
+
+void restore_processor_state(void)
+{
+	local_flush_tlb_all();
+#ifdef CONFIG_ARM_MACH_HIBERNATION_HOOK
+	mach_restore_state();
+#endif
+	local_fiq_enable();
+}
+
+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_image(void)
+{
+	extern struct pbe *restore_pblist;
+	struct pbe *pbe;
+
+	cpu_switch_mm(__virt_to_phys(swapper_pg_dir), &init_mm);
+
+	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..7308d6c
--- /dev/null
+++ b/arch/arm/kernel/swsusp.S
@@ -0,0 +1,87 @@
+/*
+ * 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/asm-offsets.h>
+#include <asm/glue-proc.h>
+
+
+/*
+ * Save the current CPU state before suspend / poweroff.
+ */
+ENTRY(swsusp_arch_suspend)
+	ldr	r0, =__swsusp_arch_ctx
+	mrs	r1, cpsr
+	mrs	r2, spsr
+	stmia	r0!, {r1-r11,lr}	@ CPSR, SPSR, nonvolatile regs
+	str	sp, [r0], #4		@ stack
+	stmfd	sp!, {lr}
+#ifdef	MULTI_CPU
+	ldr	r1, =processor
+	mov	lr, pc
+	ldr	pc, [r1, #CPU_DO_SUSPEND]
+#else
+	bl	cpu_do_suspend
+#endif
+	ldmfd	sp!, {lr}
+	b	swsusp_save		@ let framework write snapshot out
+ENDPROC(swsusp_arch_suspend)
+
+/*
+ * Restore the memory image from the pagelists, and load the CPU registers
+ * from saved state.
+ */
+ENTRY(swsusp_arch_resume)
+	/*
+	 * Switch stack to a nosavedata region to make sure image restore
+	 * doesn't clobber it underneath itself.
+	 */
+	ldr	sp, =(__swsusp_resume_stk + PAGE_SIZE / 2)
+	bl	__swsusp_arch_restore_image
+
+	/*
+	 * Restore the CPU registers.
+	 */
+	ldr	r0, =__swsusp_arch_ctx
+	ldmia	r0!, {r1,r2}		@ CPSR / SPSR
+	msr	cpsr, r1
+	msr	spsr, r2
+	ldr	r0, =__swsusp_arch_ctx	@ reload in case regset switched
+	ldmia	r0!, {r1-r11,lr}	@ nonvolatile regs
+	ldr	sp, [r0], #4		@ stack
+
+	/*
+	 * From here on we have a valid stack again. Core state is
+	 * not restored yet, redirect to the machine-specific
+	 * implementation to get that done.
+	 * Resume has succeeded at this point; if the machine-specific
+	 * code wants to fail it needs to panic.
+	 */
+	mov	r1, #0
+	stmfd	sp!, {r1,r4-r11,lr}
+#ifdef MULTI_CPU
+	ldr	r1, =processor
+	mov	lr, pc
+	ldr	pc, [r1, #CPU_DO_RESUME]
+#else
+	bl	cpu_do_resume
+#endif
+	bl	cpu_init			@ reinitialize other modes
+	ldmfd	sp!, {r0,r4-r11,pc}
+ENDPROC(swsusp_arch_resume)
diff --git a/arch/arm/mm/Kconfig b/arch/arm/mm/Kconfig
index 0074b8d..c668f8f 100644
--- a/arch/arm/mm/Kconfig
+++ b/arch/arm/mm/Kconfig
@@ -627,6 +627,11 @@ 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_THUMB
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