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outdated and some of them don't adhere to the kernel's standards.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>

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)
 {