Hi.
On Thu, 2008-10-23 at 01:08 +0200, Rafael J. Wysocki wrote:
> On Thursday, 23 of October 2008, Nigel Cunningham wrote:
> > Hi.
>
> Hi,
>
> > On Wed, 2008-10-22 at 22:52 +0200, Rafael J. Wysocki wrote:
> > > From: Rafael J. Wysocki <rjw@xxxxxxx>
> > >
> > > ACPI hibernate: Add a mechanism to save/restore ACPI NVS memory
> > >
> > > According to the ACPI Specification 3.0b, Section 15.3.2,
> > > "OSPM will call the _PTS control method some time before entering a
> > > sleeping state, to allow the platform’s AML code to update this
> > > memory image before entering the sleeping state. After the system
> > > awakes from an S4 state, OSPM will restore this memory area and call
> > > the _WAK control method to enable the BIOS to reclaim its memory
> > > image." For this reason, implement a mechanism allowing us to save
> > > the NVS memory during hibernation and to restore it during the
> > > subsequent resume.
> > >
> > > Based on a patch by Zhang Rui.
> > >
> > > Signed-off-by: Rafael J. Wysocki <rjw@xxxxxxx>
> > > Cc: Zhang Rui <rui.zhang@xxxxxxxxx>
> > > ---
> > > drivers/acpi/sleep/main.c | 50 ++++++++++++++++---
> > > include/linux/suspend.h | 13 ++++
> > > kernel/power/swsusp.c | 121 ++++++++++++++++++++++++++++++++++++++++++++++
> > > 3 files changed, 177 insertions(+), 7 deletions(-)
> > >
> > > Index: linux-2.6/drivers/acpi/sleep/main.c
> > > ===================================================================
> > > --- linux-2.6.orig/drivers/acpi/sleep/main.c
> > > +++ linux-2.6/drivers/acpi/sleep/main.c
> > > @@ -321,8 +321,23 @@ void __init acpi_no_s4_hw_signature(void
> > >
> > > static int acpi_hibernation_begin(void)
> > > {
> > > - acpi_target_sleep_state = ACPI_STATE_S4;
> > > - return 0;
> > > + int error;
> > > +
> > > + error = hibernate_nvs_alloc();
> > > + if (!error)
> > > + acpi_target_sleep_state = ACPI_STATE_S4;
> > > +
> > > + return error;
> > > +}
> > > +
> > > +static int acpi_hibernation_pre_snapshot(void)
> > > +{
> > > + int error = acpi_pm_prepare();
> > > +
> > > + if (!error)
> > > + hibernate_nvs_save();
> > > +
> > > + return error;
> > > }
> > >
> > > static int acpi_hibernation_enter(void)
> > > @@ -343,6 +358,12 @@ static int acpi_hibernation_enter(void)
> > > return ACPI_SUCCESS(status) ? 0 : -EFAULT;
> > > }
> > >
> > > +static void acpi_hibernation_finish(void)
> > > +{
> > > + hibernate_nvs_free();
> > > + acpi_pm_finish();
> > > +}
> > > +
> > > static void acpi_hibernation_leave(void)
> > > {
> > > /*
> > > @@ -358,6 +379,8 @@ static void acpi_hibernation_leave(void)
> > > "cannot resume!\n");
> > > panic("ACPI S4 hardware signature mismatch");
> > > }
> > > + /* Restore the NVS memory area */
> > > + hibernate_nvs_restore();
> > > }
> > >
> > > static void acpi_pm_enable_gpes(void)
> > > @@ -368,8 +391,8 @@ static void acpi_pm_enable_gpes(void)
> > > static struct platform_hibernation_ops acpi_hibernation_ops = {
> > > .begin = acpi_hibernation_begin,
> > > .end = acpi_pm_end,
> > > - .pre_snapshot = acpi_pm_prepare,
> > > - .finish = acpi_pm_finish,
> > > + .pre_snapshot = acpi_hibernation_pre_snapshot,
> > > + .finish = acpi_hibernation_finish,
> > > .prepare = acpi_pm_prepare,
> > > .enter = acpi_hibernation_enter,
> > > .leave = acpi_hibernation_leave,
> > > @@ -387,8 +410,21 @@ static int acpi_hibernation_begin_old(vo
> > > {
> > > int error = acpi_sleep_prepare(ACPI_STATE_S4);
> > >
> > > + if (!error) {
> > > + error = hibernate_nvs_alloc();
> > > + if (!error)
> > > + acpi_target_sleep_state = ACPI_STATE_S4;
> > > + }
> > > + return error;
> > > +}
> > > +
> > > +static int acpi_hibernation_pre_snapshot_old(void)
> > > +{
> > > + int error = acpi_pm_disable_gpes();
> > > +
> > > if (!error)
> > > - acpi_target_sleep_state = ACPI_STATE_S4;
> > > + hibernate_nvs_save();
> > > +
> > > return error;
> > > }
> > >
> > > @@ -399,8 +435,8 @@ static int acpi_hibernation_begin_old(vo
> > > static struct platform_hibernation_ops acpi_hibernation_ops_old = {
> > > .begin = acpi_hibernation_begin_old,
> > > .end = acpi_pm_end,
> > > - .pre_snapshot = acpi_pm_disable_gpes,
> > > - .finish = acpi_pm_finish,
> > > + .pre_snapshot = acpi_hibernation_pre_snapshot_old,
> > > + .finish = acpi_hibernation_finish,
> > > .prepare = acpi_pm_disable_gpes,
> > > .enter = acpi_hibernation_enter,
> > > .leave = acpi_hibernation_leave,
> > > Index: linux-2.6/include/linux/suspend.h
> > > ===================================================================
> > > --- linux-2.6.orig/include/linux/suspend.h
> > > +++ linux-2.6/include/linux/suspend.h
> > > @@ -233,6 +233,11 @@ extern unsigned long get_safe_page(gfp_t
> > > extern void hibernation_set_ops(struct platform_hibernation_ops *ops);
> > > extern int hibernate(void);
> > > extern bool system_entering_hibernation(void);
> > > +extern int hibernate_nvs_register(unsigned long start, unsigned long size);
> > > +extern int hibernate_nvs_alloc(void);
> > > +extern void hibernate_nvs_free(void);
> > > +extern void hibernate_nvs_save(void);
> > > +extern void hibernate_nvs_restore(void);
> > > #else /* CONFIG_HIBERNATION */
> > > static inline int swsusp_page_is_forbidden(struct page *p) { return 0; }
> > > static inline void swsusp_set_page_free(struct page *p) {}
> > > @@ -241,6 +246,14 @@ static inline void swsusp_unset_page_fre
> > > static inline void hibernation_set_ops(struct platform_hibernation_ops *ops) {}
> > > static inline int hibernate(void) { return -ENOSYS; }
> > > static inline bool system_entering_hibernation(void) { return false; }
> > > +static inline int hibernate_nvs_register(unsigned long a, unsigned long b)
> > > +{
> > > + return 0;
> > > +}
> > > +static inline int hibernate_nvs_alloc(void) { return 0; }
> > > +static inline void hibernate_nvs_free(void) {}
> > > +static inline void hibernate_nvs_save(void) {}
> > > +static inline void hibernate_nvs_restore(void) {}
> > > #endif /* CONFIG_HIBERNATION */
> > >
> > > #ifdef CONFIG_PM_SLEEP
> > > Index: linux-2.6/kernel/power/swsusp.c
> > > ===================================================================
> > > --- linux-2.6.orig/kernel/power/swsusp.c
> > > +++ linux-2.6/kernel/power/swsusp.c
> > > @@ -262,3 +262,124 @@ int swsusp_shrink_memory(void)
> > >
> > > return 0;
> > > }
> > > +
> > > +/*
> > > + * Platforms, like ACPI, may want us to save some memory used by them during
> > > + * hibernation and to restore the contents of this memory during the subsequent
> > > + * resume. The code below implements a mechanism allowing us to do that.
> > > + */
> > > +
> > > +struct nvs_page {
> > > + unsigned long phys_start;
> > > + unsigned int size;
> > > + void *kaddr;
> > > + void *data;
> > > + struct list_head node;
> > > +};
> > > +
> > > +static LIST_HEAD(nvs_list);
> > > +
> > > +/**
> > > + * hibernate_nvs_register - register platform NVS memory region to save
> > > + * @start - physical address of the region
> > > + * @size - size of the region
> > > + *
> > > + * The NVS region need not be page-aligned (both ends) and we arrange
> > > + * things so that the data from page-aligned addresses in this region will
> > > + * be copied into separate RAM pages.
> > > + */
> > > +int hibernate_nvs_register(unsigned long start, unsigned long size)
> > > +{
> > > + struct nvs_page *entry, *next;
> > > +
> > > + while (size > 0) {
> > > + unsigned int nr_bytes;
> > > +
> > > + entry = kzalloc(sizeof(struct nvs_page), GFP_KERNEL);
> > > + if (!entry)
> > > + goto Error;
> > > +
> > > + list_add_tail(&entry->node, &nvs_list);
> > > + entry->phys_start = start;
> > > + nr_bytes = PAGE_SIZE - (start & ~PAGE_MASK);
> > > + entry->size = (size < nr_bytes) ? size : nr_bytes;
> > > +
> > > + start += entry->size;
> > > + size -= entry->size;
> > > + }
> > > + return 0;
> > > +
> > > + Error:
> > > + list_for_each_entry_safe(entry, next, &nvs_list, node) {
> > > + list_del(&entry->node);
> > > + kfree(entry);
> > > + }
> > > + return -ENOMEM;
> > > +}
> > > +
> > > +/**
> > > + * hibernate_nvs_free - free data pages allocated for saving NVS regions
> > > + *
> > > + * It is allowed to call this function many times in a row.
> > > + */
> >
> > If this one is safe for multiple calls, should nvs_alloc be safe for
> > multiple calls too? Or, conversely, is something funny going on such
> > that hibernate_nvs_free needs to be safe for multiple calls?
>
> I thought it would be necessary to call that additionally from platform_end()
> for the error path in which platform_pre_snapshot() fails, but that doesn't
> seem to be the case. It doesn't hurt to keep it in this form, though, IMO.
Okee doke.
> > > +void hibernate_nvs_free(void)
> > > +{
> > > + struct nvs_page *entry;
> > > +
> > > + list_for_each_entry(entry, &nvs_list, node)
> > > + if (entry->data) {
> > > + free_page((unsigned long)entry->data);
> > > + entry->data = NULL;
> > > + if (entry->kaddr) {
> > > + iounmap(entry->kaddr);
> > > + entry->kaddr = NULL;
> > > + }
> > > + }
> > > +}
> > > +
> > > +/**
> > > + * hibernate_nvs_alloc - allocate memory necessary for saving NVS regions
> > > + */
> > > +int hibernate_nvs_alloc(void)
> > > +{
> > > + struct nvs_page *entry;
> > > +
> > > + list_for_each_entry(entry, &nvs_list, node) {
> > > + entry->data = (void *)__get_free_page(GFP_KERNEL);
> > > + if (!entry->data) {
> > > + hibernate_nvs_free();
> > > + return -ENOMEM;
> > > + }
> > > + }
> > > + return 0;
> > > +}
> > > +
> > > +/**
> > > + * hibernate_nvs_save - save NVS memory regions
> > > + */
> > > +void hibernate_nvs_save(void)
> > > +{
> > > + struct nvs_page *entry;
> > > +
> > > + printk(KERN_INFO "PM: Saving platform NVS memory\n");
> > > +
> > > + list_for_each_entry(entry, &nvs_list, node)
> > > + if (entry->data) {
> > > + entry->kaddr = ioremap(entry->phys_start, entry->size);
> > > + memcpy(entry->data, entry->kaddr, entry->size);
> >
> > Why not unmap here? (I know you're delaying the unmap until the free,
> > but it's probably clearer to map and unmap each time the memory is
> > accessed (ie in restore too).
>
> Ah, this one is tricky. We cannot unmap from atomic context. :-)
Maybe a comment then, lest someone get the same idea in future and be as
ignorant as me? :)
> > > + }
> > > +}
> > > +
> > > +/**
> > > + * hibernate_nvs_restore - restore NVS memory regions
> > > + */
> > > +void hibernate_nvs_restore(void)
> > > +{
> > > + struct nvs_page *entry;
> > > +
> > > + printk(KERN_INFO "PM: Restoring platform NVS memory\n");
> > > +
> > > + list_for_each_entry(entry, &nvs_list, node)
> > > + if (entry->data)
> > > + memcpy(entry->kaddr, entry->data, entry->size);
> > > +}
>
> Thanks,
> Rafael
Acked-by: Nigel Cunningham <nigel@xxxxxxxxxxxx>
Regards,
Nigel
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