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authorRafael J. Wysocki <rjw@sisk.pl>2011-05-24 23:36:06 +0200
committerRafael J. Wysocki <rjw@sisk.pl>2011-05-24 23:36:06 +0200
commitf42a9813fbf930fea3bdd0524dcb43c7feb0c977 (patch)
tree9396a7cf0b18ff2ce04cbe4698466ad6196afc75 /kernel/power
parent354258011e8e86961f7a72ad154ca8caf0c4c6f7 (diff)
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PM / Hibernate: Update kerneldoc comments in hibernate.c
Some of the kerneldoc comments in kernel/power/hibernate.c are outdated and some of them don't adhere to the kernel's standards. Update them and make them look in a consistent way. Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl> Acked-by: Randy Dunlap <randy.dunlap@oracle.com>
Diffstat (limited to 'kernel/power')
-rw-r--r--kernel/power/hibernate.c194
1 files changed, 104 insertions, 90 deletions
diff --git a/kernel/power/hibernate.c b/kernel/power/hibernate.c
index 16aa3bcd6b54..8f7b1db1ece1 100644
--- a/kernel/power/hibernate.c
+++ b/kernel/power/hibernate.c
@@ -54,10 +54,9 @@ static int hibernation_mode = HIBERNATION_SHUTDOWN;
static const struct platform_hibernation_ops *hibernation_ops;
/**
- * hibernation_set_ops - set the global hibernate operations
- * @ops: the hibernation operations to use in subsequent hibernation transitions
+ * hibernation_set_ops - Set the global hibernate operations.
+ * @ops: Hibernation operations to use in subsequent hibernation transitions.
*/
-
void hibernation_set_ops(const struct platform_hibernation_ops *ops)
{
if (ops && !(ops->begin && ops->end && ops->pre_snapshot
@@ -114,10 +113,9 @@ static int hibernation_test(int level) { return 0; }
#endif /* !CONFIG_PM_DEBUG */
/**
- * platform_begin - tell the platform driver that we're starting
- * hibernation
+ * platform_begin - Call platform to start hibernation.
+ * @platform_mode: Whether or not to use the platform driver.
*/
-
static int platform_begin(int platform_mode)
{
return (platform_mode && hibernation_ops) ?
@@ -125,10 +123,9 @@ static int platform_begin(int platform_mode)
}
/**
- * platform_end - tell the platform driver that we've entered the
- * working state
+ * platform_end - Call platform to finish transition to the working state.
+ * @platform_mode: Whether or not to use the platform driver.
*/
-
static void platform_end(int platform_mode)
{
if (platform_mode && hibernation_ops)
@@ -136,8 +133,11 @@ static void platform_end(int platform_mode)
}
/**
- * platform_pre_snapshot - prepare the machine for hibernation using the
- * platform driver if so configured and return an error code if it fails
+ * platform_pre_snapshot - Call platform to prepare the machine for hibernation.
+ * @platform_mode: Whether or not to use the platform driver.
+ *
+ * Use the platform driver to prepare the system for creating a hibernate image,
+ * if so configured, and return an error code if that fails.
*/
static int platform_pre_snapshot(int platform_mode)
@@ -147,10 +147,14 @@ static int platform_pre_snapshot(int platform_mode)
}
/**
- * platform_leave - prepare the machine for switching to the normal mode
- * of operation using the platform driver (called with interrupts disabled)
+ * platform_leave - Call platform to prepare a transition to the working state.
+ * @platform_mode: Whether or not to use the platform driver.
+ *
+ * Use the platform driver prepare to prepare the machine for switching to the
+ * normal mode of operation.
+ *
+ * This routine is called on one CPU with interrupts disabled.
*/
-
static void platform_leave(int platform_mode)
{
if (platform_mode && hibernation_ops)
@@ -158,10 +162,14 @@ static void platform_leave(int platform_mode)
}
/**
- * platform_finish - switch the machine to the normal mode of operation
- * using the platform driver (must be called after platform_prepare())
+ * platform_finish - Call platform to switch the system to the working state.
+ * @platform_mode: Whether or not to use the platform driver.
+ *
+ * Use the platform driver to switch the machine to the normal mode of
+ * operation.
+ *
+ * This routine must be called after platform_prepare().
*/
-
static void platform_finish(int platform_mode)
{
if (platform_mode && hibernation_ops)
@@ -169,11 +177,15 @@ static void platform_finish(int platform_mode)
}
/**
- * platform_pre_restore - prepare the platform for the restoration from a
- * hibernation image. If the restore fails after this function has been
- * called, platform_restore_cleanup() must be called.
+ * platform_pre_restore - Prepare for hibernate image restoration.
+ * @platform_mode: Whether or not to use the platform driver.
+ *
+ * Use the platform driver to prepare the system for resume from a hibernation
+ * image.
+ *
+ * If the restore fails after this function has been called,
+ * platform_restore_cleanup() must be called.
*/
-
static int platform_pre_restore(int platform_mode)
{
return (platform_mode && hibernation_ops) ?
@@ -181,12 +193,16 @@ static int platform_pre_restore(int platform_mode)
}
/**
- * platform_restore_cleanup - switch the platform to the normal mode of
- * operation after a failing restore. If platform_pre_restore() has been
- * called before the failing restore, this function must be called too,
- * regardless of the result of platform_pre_restore().
+ * platform_restore_cleanup - Switch to the working state after failing restore.
+ * @platform_mode: Whether or not to use the platform driver.
+ *
+ * Use the platform driver to switch the system to the normal mode of operation
+ * after a failing restore.
+ *
+ * If platform_pre_restore() has been called before the failing restore, this
+ * function must be called too, regardless of the result of
+ * platform_pre_restore().
*/
-
static void platform_restore_cleanup(int platform_mode)
{
if (platform_mode && hibernation_ops)
@@ -194,10 +210,9 @@ static void platform_restore_cleanup(int platform_mode)
}
/**
- * platform_recover - recover the platform from a failure to suspend
- * devices.
+ * platform_recover - Recover from a failure to suspend devices.
+ * @platform_mode: Whether or not to use the platform driver.
*/
-
static void platform_recover(int platform_mode)
{
if (platform_mode && hibernation_ops && hibernation_ops->recover)
@@ -205,13 +220,12 @@ static void platform_recover(int platform_mode)
}
/**
- * swsusp_show_speed - print the time elapsed between two events.
- * @start: Starting event.
- * @stop: Final event.
- * @nr_pages - number of pages processed between @start and @stop
- * @msg - introductory message to print
+ * swsusp_show_speed - Print time elapsed between two events during hibernation.
+ * @start: Starting event.
+ * @stop: Final event.
+ * @nr_pages: Number of memory pages processed between @start and @stop.
+ * @msg: Additional diagnostic message to print.
*/
-
void swsusp_show_speed(struct timeval *start, struct timeval *stop,
unsigned nr_pages, char *msg)
{
@@ -234,11 +248,14 @@ void swsusp_show_speed(struct timeval *start, struct timeval *stop,
}
/**
- * create_image - freeze devices that need to be frozen with interrupts
- * off, create the hibernation image and thaw those devices. Control
- * reappears in this routine after a restore.
+ * create_image - Create a hibernation image.
+ * @platform_mode: Whether or not to use the platform driver.
+ *
+ * Execute device drivers' .freeze_noirq() callbacks, create a hibernation image
+ * and execute the drivers' .thaw_noirq() callbacks.
+ *
+ * Control reappears in this routine after the subsequent restore.
*/
-
static int create_image(int platform_mode)
{
int error;
@@ -303,14 +320,11 @@ static int create_image(int platform_mode)
}
/**
- * hibernation_snapshot - quiesce devices and create the hibernation
- * snapshot image.
- * @platform_mode - if set, use the platform driver, if available, to
- * prepare the platform firmware for the power transition.
+ * hibernation_snapshot - Quiesce devices and create a hibernation image.
+ * @platform_mode: If set, use platform driver to prepare for the transition.
*
- * Must be called with pm_mutex held
+ * This routine must be called with pm_mutex held.
*/
-
int hibernation_snapshot(int platform_mode)
{
pm_message_t msg = PMSG_RECOVER;
@@ -370,13 +384,14 @@ int hibernation_snapshot(int platform_mode)
}
/**
- * resume_target_kernel - prepare devices that need to be suspended with
- * interrupts off, restore the contents of highmem that have not been
- * restored yet from the image and run the low level code that will restore
- * the remaining contents of memory and switch to the just restored target
- * kernel.
+ * resume_target_kernel - Restore system state from a hibernation image.
+ * @platform_mode: Whether or not to use the platform driver.
+ *
+ * Execute device drivers' .freeze_noirq() callbacks, restore the contents of
+ * highmem that have not been restored yet from the image and run the low-level
+ * code that will restore the remaining contents of memory and switch to the
+ * just restored target kernel.
*/
-
static int resume_target_kernel(bool platform_mode)
{
int error;
@@ -444,14 +459,12 @@ static int resume_target_kernel(bool platform_mode)
}
/**
- * hibernation_restore - quiesce devices and restore the hibernation
- * snapshot image. If successful, control returns in hibernation_snaphot()
- * @platform_mode - if set, use the platform driver, if available, to
- * prepare the platform firmware for the transition.
+ * hibernation_restore - Quiesce devices and restore from a hibernation image.
+ * @platform_mode: If set, use platform driver to prepare for the transition.
*
- * Must be called with pm_mutex held
+ * This routine must be called with pm_mutex held. If it is successful, control
+ * reappears in the restored target kernel in hibernation_snaphot().
*/
-
int hibernation_restore(int platform_mode)
{
int error;
@@ -471,10 +484,8 @@ int hibernation_restore(int platform_mode)
}
/**
- * hibernation_platform_enter - enter the hibernation state using the
- * platform driver (if available)
+ * hibernation_platform_enter - Power off the system using the platform driver.
*/
-
int hibernation_platform_enter(void)
{
int error;
@@ -545,12 +556,12 @@ int hibernation_platform_enter(void)
}
/**
- * power_down - Shut the machine down for hibernation.
+ * power_down - Shut the machine down for hibernation.
*
- * Use the platform driver, if configured so; otherwise try
- * to power off or reboot.
+ * Use the platform driver, if configured, to put the system into the sleep
+ * state corresponding to hibernation, or try to power it off or reboot,
+ * depending on the value of hibernation_mode.
*/
-
static void power_down(void)
{
switch (hibernation_mode) {
@@ -587,9 +598,8 @@ static int prepare_processes(void)
}
/**
- * hibernate - The granpappy of the built-in hibernation management
+ * hibernate - Carry out system hibernation, including saving the image.
*/
-
int hibernate(void)
{
int error;
@@ -667,17 +677,20 @@ int hibernate(void)
/**
- * software_resume - Resume from a saved image.
+ * software_resume - Resume from a saved hibernation image.
+ *
+ * This routine is called as a late initcall, when all devices have been
+ * discovered and initialized already.
*
- * 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 hibernate() ) if everything goes well.
- * Otherwise, we fail gracefully and return to the normally
- * scheduled program.
+ * The image reading code is called to see if there is a hibernation image
+ * available for reading. If that is the case, devices are quiesced and the
+ * contents of memory is restored from the saved image.
*
+ * If this is successful, control reappears in the restored target kernel in
+ * hibernation_snaphot() which returns to hibernate(). Otherwise, the routine
+ * attempts to recover gracefully and make the kernel return to the normal mode
+ * of operation.
*/
-
static int software_resume(void)
{
int error;
@@ -807,21 +820,17 @@ static const char * const hibernation_modes[] = {
[HIBERNATION_TESTPROC] = "testproc",
};
-/**
- * disk - Control hibernation mode
- *
- * Suspend-to-disk can be handled in several ways. We have a few options
- * for putting the system to sleep - using the platform driver (e.g. ACPI
- * or other hibernation_ops), powering off the system or rebooting the
- * system (for testing) as well as the two test modes.
+/*
+ * /sys/power/disk - Control hibernation mode.
*
- * The system can support 'platform', and that is known a priori (and
- * encoded by the presence of hibernation_ops). However, the user may
- * choose 'shutdown' or 'reboot' as alternatives, as well as one fo the
- * test modes, 'test' or 'testproc'.
+ * Hibernation can be handled in several ways. There are a few different ways
+ * to put the system into the sleep state: using the platform driver (e.g. ACPI
+ * or other hibernation_ops), powering it off or rebooting it (for testing
+ * mostly), or using one of the two available test modes.
*
- * show() will display what the mode is currently set to.
- * store() will accept one of
+ * The sysfs file /sys/power/disk provides an interface for selecting the
+ * hibernation mode to use. Reading from this file causes the available modes
+ * to be printed. There are 5 modes that can be supported:
*
* 'platform'
* 'shutdown'
@@ -829,8 +838,14 @@ static const char * const hibernation_modes[] = {
* 'test'
* 'testproc'
*
- * It will only change to 'platform' if the system
- * supports it (as determined by having hibernation_ops).
+ * If a platform hibernation driver is in use, 'platform' will be supported
+ * and will be used by default. Otherwise, 'shutdown' will be used by default.
+ * The selected option (i.e. the one corresponding to the current value of
+ * hibernation_mode) is enclosed by a square bracket.
+ *
+ * To select a given hibernation mode it is necessary to write the mode's
+ * string representation (as returned by reading from /sys/power/disk) back
+ * into /sys/power/disk.
*/
static ssize_t disk_show(struct kobject *kobj, struct kobj_attribute *attr,
@@ -863,7 +878,6 @@ static ssize_t disk_show(struct kobject *kobj, struct kobj_attribute *attr,
return buf-start;
}
-
static ssize_t disk_store(struct kobject *kobj, struct kobj_attribute *attr,
const char *buf, size_t n)
{