PM / Hibernate: Enable suspend to both for in-kernel hibernation.

It is often useful to suspend to memory after hibernation image has been
written to disk. If the battery runs out or power is otherwise lost, the
computer will resume from the hibernated image. If not, it will resume
from memory and hibernation image will be discarded.

Signed-off-by: Bojan Smojver <bojan@rexursive.com>
Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>

kernel/power/hibernate.c

@@ -5,6 +5,7 @@
  * Copyright (c) 2003 Open Source Development Lab
  * Copyright (c) 2004 Pavel Machek <pavel@ucw.cz>
  * Copyright (c) 2009 Rafael J. Wysocki, Novell Inc.
+ * Copyright (C) 2012 Bojan Smojver <bojan@rexursive.com>
  *
  * This file is released under the GPLv2.
  */
@@ -46,6 +47,9 @@ enum {
 	HIBERNATION_PLATFORM,
 	HIBERNATION_SHUTDOWN,
 	HIBERNATION_REBOOT,
+#ifdef CONFIG_SUSPEND
+	HIBERNATION_SUSPEND,
+#endif
 	/* keep last */
 	__HIBERNATION_AFTER_LAST
 };
@@ -574,6 +578,10 @@ int hibernation_platform_enter(void)
  */
 static void power_down(void)
 {
+#ifdef CONFIG_SUSPEND
+	int error;
+#endif
+
 	switch (hibernation_mode) {
 	case HIBERNATION_REBOOT:
 		kernel_restart(NULL);
@@ -583,6 +591,25 @@ static void power_down(void)
 	case HIBERNATION_SHUTDOWN:
 		kernel_power_off();
 		break;
+#ifdef CONFIG_SUSPEND
+	case HIBERNATION_SUSPEND:
+		error = suspend_devices_and_enter(PM_SUSPEND_MEM);
+		if (error) {
+			if (hibernation_ops)
+				hibernation_mode = HIBERNATION_PLATFORM;
+			else
+				hibernation_mode = HIBERNATION_SHUTDOWN;
+			power_down();
+		}
+		/*
+		 * Restore swap signature.
+		 */
+		error = swsusp_unmark();
+		if (error)
+			printk(KERN_ERR "PM: Swap will be unusable! "
+			                "Try swapon -a.\n");
+		return;
+#endif
 	}
 	kernel_halt();
 	/*
@@ -827,6 +854,9 @@ static const char * const hibernation_modes[] = {
 	[HIBERNATION_PLATFORM]	= "platform",
 	[HIBERNATION_SHUTDOWN]	= "shutdown",
 	[HIBERNATION_REBOOT]	= "reboot",
+#ifdef CONFIG_SUSPEND
+	[HIBERNATION_SUSPEND]	= "suspend",
+#endif
 };
 
 /*
@@ -867,6 +897,9 @@ static ssize_t disk_show(struct kobject *kobj, struct kobj_attribute *attr,
 		switch (i) {
 		case HIBERNATION_SHUTDOWN:
 		case HIBERNATION_REBOOT:
+#ifdef CONFIG_SUSPEND
+		case HIBERNATION_SUSPEND:
+#endif
 			break;
 		case HIBERNATION_PLATFORM:
 			if (hibernation_ops)
@@ -907,6 +940,9 @@ static ssize_t disk_store(struct kobject *kobj, struct kobj_attribute *attr,
 		switch (mode) {
 		case HIBERNATION_SHUTDOWN:
 		case HIBERNATION_REBOOT:
+#ifdef CONFIG_SUSPEND
+		case HIBERNATION_SUSPEND:
+#endif
 			hibernation_mode = mode;
 			break;
 		case HIBERNATION_PLATFORM:

kernel/power/power.h

@@ -156,6 +156,9 @@ extern void swsusp_free(void);
 extern int swsusp_read(unsigned int *flags_p);
 extern int swsusp_write(unsigned int flags);
 extern void swsusp_close(fmode_t);
+#ifdef CONFIG_SUSPEND
+extern int swsusp_unmark(void);
+#endif
 
 /* kernel/power/block_io.c */
 extern struct block_device *hib_resume_bdev;

kernel/power/swap.c

@@ -1472,6 +1472,34 @@ void swsusp_close(fmode_t mode)
 	blkdev_put(hib_resume_bdev, mode);
 }
 
+/**
+ *      swsusp_unmark - Unmark swsusp signature in the resume device
+ */
+
+#ifdef CONFIG_SUSPEND
+int swsusp_unmark(void)
+{
+	int error;
+
+	hib_bio_read_page(swsusp_resume_block, swsusp_header, NULL);
+	if (!memcmp(HIBERNATE_SIG,swsusp_header->sig, 10)) {
+		memcpy(swsusp_header->sig,swsusp_header->orig_sig, 10);
+		error = hib_bio_write_page(swsusp_resume_block,
+					swsusp_header, NULL);
+	} else {
+		printk(KERN_ERR "PM: Cannot find swsusp signature!\n");
+		error = -ENODEV;
+	}
+
+	/*
+	 * We just returned from suspend, we don't need the image any more.
+	 */
+	free_all_swap_pages(root_swap);
+
+	return error;
+}
+#endif
+
 static int swsusp_header_init(void)
 {
 	swsusp_header = (struct swsusp_header*) __get_free_page(GFP_KERNEL);