[power] Separate suspend-to-disk from other suspend sequences.

- Put in kernel/power/disk.c
- Make compilation depend on CONFIG_SOFTWARE_SUSPEND (should probably be 
  renamed to CONFIG_PM_STD or some such).

kernel/power/Makefile

 obj-y				:= main.o process.o console.o pm.o
-obj-$(CONFIG_SOFTWARE_SUSPEND)	+= swsusp.o
+obj-$(CONFIG_SOFTWARE_SUSPEND)	+= disk.o swsusp.o
 
 obj-$(CONFIG_MAGIC_SYSRQ)	+= poweroff.o

kernel/power/disk.c

+/*
+ * kernel/power/disk.c - Suspend-to-disk support.
+ *
+ * Copyright (c) 2003 Patrick Mochel
+ * Copyright (c) 2003 Open Source Development Lab
+ * 
+ * This file is release under the GPLv2
+ *
+ */
+
+#define DEBUG
+
+
+#include <linux/suspend.h>
+#include <linux/reboot.h>
+#include <linux/string.h>
+#include <linux/delay.h>
+#include <linux/fs.h>
+#include "power.h"
+
+
+extern u32 pm_disk_mode;
+extern struct pm_ops * pm_ops;
+
+extern int swsusp_save(void);
+extern int swsusp_write(void);
+extern int swsusp_read(void);
+extern int swsusp_restore(void);
+extern int swsusp_free(void);
+
+extern long sys_sync(void);
+
+
+/**
+ *	power_down - Shut machine down for hibernate.
+ *	@mode:		Suspend-to-disk mode
+ *
+ *	Use the platform driver, if configured so, and return gracefully if it
+ *	fails. 
+ *	Otherwise, try to power off and reboot. If they fail, halt the machine,
+ *	there ain't no turning back.
+ */
+
+static int power_down(u32 mode)
+{
+	unsigned long flags;
+	int error = 0;
+
+	local_irq_save(flags);
+	device_power_down(PM_SUSPEND_DISK);
+	switch(mode) {
+	case PM_DISK_PLATFORM:
+		error = pm_ops->enter(PM_SUSPEND_DISK);
+		break;
+	case PM_DISK_SHUTDOWN:
+		printk("Powering off system\n");
+		machine_power_off();
+		break;
+	case PM_DISK_REBOOT:
+		machine_restart(NULL);
+		break;
+	}
+	machine_halt();
+	device_power_up();
+	local_irq_restore(flags);
+	return 0;
+}
+
+
+static int in_suspend __nosavedata = 0;
+
+
+/**
+ *	free_some_memory -  Try to free as much memory as possible
+ *
+ *	... but do not OOM-kill anyone
+ *
+ *	Notice: all userland should be stopped at this point, or 
+ *	livelock is possible.
+ */
+
+static void free_some_memory(void)
+{
+	printk("Freeing memory: ");
+	while (shrink_all_memory(10000))
+		printk(".");
+	printk("|\n");
+	blk_run_queues();
+}
+
+
+static inline void platform_finish(void)
+{
+	if (pm_disk_mode == PM_DISK_PLATFORM) {
+		if (pm_ops && pm_ops->finish)
+			pm_ops->finish(PM_SUSPEND_DISK);
+	}
+}
+
+static void finish(void)
+{
+	device_resume();
+	platform_finish();
+	thaw_processes();
+	pm_restore_console();
+}
+
+
+static int prepare(void)
+{
+	int error;
+
+	pm_prepare_console();
+
+	sys_sync();
+	if (freeze_processes()) {
+		error = -EBUSY;
+		goto Thaw;
+	}
+
+	if (pm_disk_mode == PM_DISK_PLATFORM) {
+		if (pm_ops && pm_ops->prepare) {
+			if ((error = pm_ops->prepare(PM_SUSPEND_DISK)))
+				goto Thaw;
+		}
+	}
+
+	/* Free memory before shutting down devices. */
+	free_some_memory();
+
+	if ((error = device_suspend(PM_SUSPEND_DISK)))
+		goto Finish;
+
+	return 0;
+ Finish:
+	platform_finish();
+ Thaw:
+	thaw_processes();
+	pm_restore_console();
+	return error;
+}
+
+
+/**
+ *	pm_suspend_disk - The granpappy of power management.
+ *	
+ *	If we're going through the firmware, then get it over with quickly.
+ *
+ *	If not, then call swsusp to do it's thing, then figure out how
+ *	to power down the system.
+ */
+
+int pm_suspend_disk(void)
+{
+	int error;
+
+	if ((error = prepare()))
+		return error;
+
+	pr_debug("PM: Attempting to suspend to disk.\n");
+	if (pm_disk_mode == PM_DISK_FIRMWARE)
+		return pm_ops->enter(PM_SUSPEND_DISK);
+
+	pr_debug("PM: snapshotting memory.\n");
+	in_suspend = 1;
+	local_irq_disable();
+	if ((error = swsusp_save()))
+		goto Done;
+
+	pr_debug("PM: writing image.\n");
+
+	/* 
+	 * FIXME: Leftover from swsusp. Are they necessary? 
+	 */
+	mb();
+	barrier();
+
+	error = swsusp_write();
+	if (!error && in_suspend) {
+		error = power_down(pm_disk_mode);
+		pr_debug("PM: Power down failed.\n");
+	} else
+		pr_debug("PM: Image restored successfully.\n");
+	swsusp_free();
+ Done:
+	local_irq_enable();
+	finish();
+	return error;
+}
+
+
+/**
+ *	pm_resume - Resume from a saved image.
+ *
+ *	Called as a late_initcall (so all devices are discovered and 
+ *	initialized), we call swsusp to see if we have a saved image or not.
+ *	If so, we quiesce devices, the restore the saved image. We will 
+ *	return above (in pm_suspend_disk() ) if everything goes well. 
+ *	Otherwise, we fail gracefully and return to the normally 
+ *	scheduled program.
+ *
+ */
+
+static int pm_resume(void)
+{
+	int error;
+
+	pr_debug("PM: Reading swsusp image.\n");
+
+	if ((error = swsusp_read()))
+		goto Done;
+
+	pr_debug("PM: Preparing system for restore.\n");
+
+	if ((error = prepare()))
+		goto Free;
+
+	barrier();
+	mb();
+	local_irq_disable();
+
+	/* FIXME: The following (comment and mdelay()) are from swsusp. 
+	 * Are they really necessary? 
+	 *
+	 * We do not want some readahead with DMA to corrupt our memory, right?
+	 * Do it with disabled interrupts for best effect. That way, if some
+	 * driver scheduled DMA, we have good chance for DMA to finish ;-).
+	 */
+	pr_debug("PM: Waiting for DMAs to settle down.\n");
+	mdelay(1000);
+
+	pr_debug("PM: Restoring saved image.\n");
+	swsusp_restore();
+	local_irq_enable();
+	pr_debug("PM: Restore failed, recovering.n");
+	finish();
+ Free:
+	swsusp_free();
+ Done:
+	pr_debug("PM: Resume from disk failed.\n");
+	return 0;
+}
+
+late_initcall(pm_resume);
+
+
+static char * pm_disk_modes[] = {
+	[PM_DISK_FIRMWARE]	= "firmware",
+	[PM_DISK_PLATFORM]	= "platform",
+	[PM_DISK_SHUTDOWN]	= "shutdown",
+	[PM_DISK_REBOOT]	= "reboot",
+};
+
+/**
+ *	disk - Control suspend-to-disk mode
+ *
+ *	Suspend-to-disk can be handled in several ways. The greatest 
+ *	distinction is who writes memory to disk - the firmware or the OS.
+ *	If the firmware does it, we assume that it also handles suspending 
+ *	the system.
+ *	If the OS does it, then we have three options for putting the system
+ *	to sleep - using the platform driver (e.g. ACPI or other PM registers),
+ *	powering off the system or rebooting the system (for testing). 
+ *
+ *	The system will support either 'firmware' or 'platform', and that is
+ *	known a priori (and encoded in pm_ops). But, the user may choose
+ *	'shutdown' or 'reboot' as alternatives.
+ *
+ *	show() will display what the mode is currently set to. 
+ *	store() will accept one of
+ *
+ *	'firmware'
+ *	'platform'
+ *	'shutdown'
+ *	'reboot'
+ *
+ *	It will only change to 'firmware' or 'platform' if the system
+ *	supports it (as determined from pm_ops->pm_disk_mode).
+ */
+
+static ssize_t disk_show(struct subsystem * subsys, char * buf)
+{
+	return sprintf(buf,"%s\n",pm_disk_modes[pm_disk_mode]);
+}
+
+
+static ssize_t disk_store(struct subsystem * s, const char * buf, size_t n)
+{
+	int error = 0;
+	int i;
+	u32 mode = 0;
+
+	down(&pm_sem);
+	for (i = PM_DISK_FIRMWARE; i < PM_DISK_MAX; i++) {
+		if (!strcmp(buf,pm_disk_modes[i])) {
+			mode = i;
+			break;
+		}
+	}
+	if (mode) {
+		if (mode == PM_DISK_SHUTDOWN || mode == PM_DISK_REBOOT)
+			pm_disk_mode = mode;
+		else {
+			if (pm_ops && pm_ops->enter && 
+			    (mode == pm_ops->pm_disk_mode))
+				pm_disk_mode = mode;
+			else
+				error = -EINVAL;
+		}
+	} else
+		error = -EINVAL;
+
+	pr_debug("PM: suspend-to-disk mode set to '%s'\n",
+		 pm_disk_modes[mode]);
+	up(&pm_sem);
+	return error ? error : n;
+}
+
+power_attr(disk);
+
+static struct attribute * g[] = {
+	&disk_attr.attr,
+	NULL,
+};
+
+
+static struct attribute_group attr_group = {
+	.attrs = g,
+};
+
+
+static int __init pm_disk_init(void)
+{
+	return sysfs_create_group(&power_subsys.kset.kobj,&attr_group);
+}
+
+core_initcall(pm_disk_init);

kernel/power/power.h

@@ -10,34 +10,27 @@
 
 
 #ifdef CONFIG_SOFTWARE_SUSPEND
-extern int swsusp_save(void);
-extern int swsusp_write(void);
-extern int swsusp_read(void);
-extern int swsusp_restore(void);
-extern int swsusp_free(void);
+extern int pm_suspend_disk(void);
+
 #else
-static inline int swsusp_save(void) 
-{
-	return 0;
-}
-static inline int swsusp_write(void)
+static inline int pm_suspend_disk(void)
 {
-	return 0;
-}
-static inline int swsusp_read(void)
-{
-	return 0;
-}
-static inline int swsusp_restore(void)
-{
-	return 0;
-}
-static inline int swsusp_free(void)
-{
-	return 0;
+	return -EPERM;
 }
 #endif
 
+extern struct semaphore pm_sem;
+#define power_attr(_name) \
+static struct subsys_attribute _name##_attr = {	\
+	.attr	= {				\
+		.name = __stringify(_name),	\
+		.mode = 0644,			\
+	},					\
+	.show	= _name##_show,			\
+	.store	= _name##_store,		\
+}
+
+extern struct subsystem power_subsys;
 
 extern int freeze_processes(void);
 extern void thaw_processes(void);