[RFC PATCH 2/4] ACPI: introduce the mechanism to save/restore ACPI NVS memory

Zhang Rui
2008-07-03T02:24:34Z

According to the ACPI spec, ACPI NVS memory region is required to be
saved/restored by OS during hibernation.

Section 15.3.2 ACPI Spec 3.0b,
"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."

Add the mechanism to save/restore ACPI NVS memory during hibernation.

Note: now Linux save ACPI NVS memory in acpi_hibernation_pre_snapshot, and restore it in
acpi_hibernation_leave. Both of these functions will be invoked only once during
the hibernate and resume.
Note: in Section 14.3 ACPI spec 3.0b, I only get
"EfiACPIMemoryNVS: The OS and loader must preserve this memory range in
the working and ACPI S1–S3 states."
whether we should save/restore this piece of memory is not cleared.

Signed-off-by: Zhang Rui <rui.zhang@intel.com>
---
drivers/acpi/sleep/main.c | 103 +++++++++++++++++++++++++++++++++++++++++++++-
include/linux/acpi.h | 3 +
2 files changed, 104 insertions(+), 2 deletions(-)

Index: linux-2.6/drivers/acpi/sleep/main.c
===================================================================
--- linux-2.6.orig/drivers/acpi/sleep/main.c 2008-06-30 16:28:56.000000000 +0800
+++ linux-2.6/drivers/acpi/sleep/main.c 2008-07-01 09:30:36.000000000 +0800
@@ -15,6 +15,7 @@
#include <linux/dmi.h>
#include <linux/device.h>
#include <linux/suspend.h>
+#include <linux/highmem.h>

#include <asm/io.h>

@@ -255,11 +256,91 @@
#endif /* CONFIG_SUSPEND */

#ifdef CONFIG_HIBERNATION
+
+/* ACPI NVS memory need to be saved/stored during hibernation */
+struct nvs_page {
+ unsigned long pfn;
+ void *data;
+ struct list_head node;
+};
+static LIST_HEAD(nvs_pages_list);
+
+int acpi_mark_nvs_region(unsigned long start, unsigned long end)
+{
+ struct nvs_page *pos;
+
+ while (start <= end) {
+ pos = kzalloc(sizeof(struct nvs_page), GFP_KERNEL);
+ if (!pos)
+ return -ENOMEM;
+ pos->pfn = start;
+ start++;
+ list_add_tail(&pos->node, &nvs_pages_list);
+ }
+ return 0;
+}
+
+static int acpi_free_nvs_pages(void)
+{
+ struct nvs_page *pos;
+
+ list_for_each_entry(pos, &nvs_pages_list, node) {
+ if (!pos->data)
+ break;
+ free_page((long)pos->data);
+ pos->data = NULL;
+ }
+ return 0;
+}
+
+static int acpi_allocate_nvs_pages(void)
+{
+ struct nvs_page *pos;
+
+ list_for_each_entry(pos, &nvs_pages_list, node) {
+ pos->data = (void *)__get_free_page(GFP_KERNEL);
+ if (!pos->data) {
+ acpi_free_nvs_pages();
+ return -ENOMEM;
+ }
+ }
+ return 0;
+}
+
+static void acpi_save_nvs_memory(void)
+{
+ void *kaddr;
+ struct nvs_page *pos;
+
+ pr_debug("ACPI: Saving ACPI NVS memory\n");
+ list_for_each_entry(pos, &nvs_pages_list, node) {
+ /* nvs page might not have a 'struct page' */
+ kaddr = kmap_atomic_pfn(pos->pfn, KM_USER0);
+ copy_page(pos->data, kaddr);
+ kunmap_atomic(kaddr, KM_USER0);
+ }
+ return;
+}
+
+static void acpi_restore_nvs_memory(void)
+{
+ void *kaddr;
+ struct nvs_page *pos;
+
+ pr_debug("ACPI: Restoring ACPI NVS memory\n");
+ list_for_each_entry(pos, &nvs_pages_list, node) {
+ kaddr = kmap_atomic_pfn(pos->pfn, KM_USER0);
+ copy_page(kaddr, pos->data);
+ kunmap_atomic(kaddr, KM_USER0);
+ }
+}
+
static int acpi_hibernation_begin(void)
{
acpi_target_sleep_state = ACPI_STATE_S4;

- return 0;
+ /* allocate pages for ACPI NVS memory before swsusp_shrink_memory */
+ return acpi_allocate_nvs_pages();
}

static int acpi_hibernation_prepare(void)
@@ -274,6 +355,20 @@
return ACPI_SUCCESS(acpi_hw_disable_all_gpes()) ? 0 : -EFAULT;
}

+static int acpi_hibernation_pre_snapshot(void)
+{
+ int error = acpi_sleep_prepare(ACPI_STATE_S4);
+
+ if (error) {
+ acpi_target_sleep_state = ACPI_STATE_S0;
+ return error;
+ }
+
+ acpi_save_nvs_memory();
+
+ return ACPI_SUCCESS(acpi_hw_disable_all_gpes()) ? 0 : -EFAULT;
+}
+
static int acpi_hibernation_enter(void)
{
acpi_status status = AE_OK;
@@ -301,6 +396,7 @@
acpi_enable();
/* Reprogram control registers and execute _BFS */
acpi_leave_sleep_state_prep(ACPI_STATE_S4);
+ acpi_restore_nvs_memory();
}

static void acpi_hibernation_finish(void)
@@ -321,6 +417,9 @@
* during a failing transition to the sleep state.
*/
acpi_target_sleep_state = ACPI_STATE_S0;
+
+ /* free pages allocated for ACPI NVS memory */
+ acpi_free_nvs_pages();
}

static int acpi_hibernation_pre_restore(void)
@@ -340,7 +439,7 @@
static struct platform_hibernation_ops acpi_hibernation_ops = {
.begin = acpi_hibernation_begin,
.end = acpi_hibernation_end,
- .pre_snapshot = acpi_hibernation_prepare,
+ .pre_snapshot = acpi_hibernation_pre_snapshot,
.finish = acpi_hibernation_finish,
.prepare = acpi_hibernation_prepare,
.enter = acpi_hibernation_enter,
Index: linux-2.6/include/linux/acpi.h
===================================================================
--- linux-2.6.orig/include/linux/acpi.h 2008-06-30 16:28:56.000000000 +0800
+++ linux-2.6/include/linux/acpi.h 2008-06-30 16:29:26.000000000 +0800
@@ -106,6 +106,9 @@
void acpi_numa_arch_fixup(void);
#endif

+#ifdef CONFIG_HIBERNATION
+int acpi_mark_nvs_region(unsigned long, unsigned long);
+#endif
#ifdef CONFIG_ACPI_HOTPLUG_CPU
/* Arch dependent functions for cpu hotplug support */
int acpi_map_lsapic(acpi_handle handle, int *pcpu);

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