The syscore device PM flag is used to mark the devices (belonging to
a PM domain) that should never be turned off, except for the system
core (syscore) suspend/hibernation and resume stages.  That flag is
stored in the device's struct pm_subsys_data object whose address is
available from struct device.  However, in some situations it may be
convenient to set that flag before the device is added to a PM
domain, so it is better to move it directly to the "power" member of
struct device.  Then, it can be checked by the routines in
drivers/base/power/runtime.c and drivers/base/power/main.c, which is
more straightforward.

This also reduces the number of dev_gpd_data() invocations in the
generic PM domains framework, so the overhead related to the syscore
flag is slightly smaller.
Signed-off-by: NRafael J. Wysocki <rjw@sisk.pl>
Acked-by: NMagnus Damm <damm@opensource.se>

The always_on device flag is used to mark the devices (belonging to
a PM domain) that should never be turned off, except for the system
core (syscore) suspend/hibernation and resume stages.  Change name
of that flag to "syscore" to better reflect its purpose.
Signed-off-by: NRafael J. Wysocki <rjw@sisk.pl>
Acked-by: NMagnus Damm <damm@opensource.se>

Introduce function pm_genpd_syscore_switch() and two wrappers around
it, pm_genpd_syscore_poweroff() and pm_genpd_syscore_poweron(),
allowing the callers to let the generic PM domains framework know
that the given device is not necessary any more and its PM domain
can be turned off (the former) or that the given device will be
required immediately, so its PM domain has to be turned on (the
latter) during the system core (syscore) stage of system suspend
(or hibernation) and resume.

These functions will be used for handling devices registered as
clock sources and clock event devices that belong to PM domains.
Signed-off-by: NRafael J. Wysocki <rjw@sisk.pl>

Add a mechanism for counting references to the
struct generic_pm_domain_data object pointed to by
dev->power.subsys_data->domain_data if the device in question
belongs to a generic PM domain.

This change is necessary for a subsequent patch making it possible to
allocate that object from within pm_genpd_add_callbacks(), so that
drivers can attach their PM domain device callbacks to devices before
those devices are added to PM domains.

This patch has been tested on the SH7372 Mackerel board.
Signed-off-by: NRafael J. Wysocki <rjw@sisk.pl>

On some systems there are CPU cores located in the same power
domains as I/O devices.  Then, power can only be removed from the
domain if all I/O devices in it are not in use and the CPU core
is idle.  Add preliminary support for that to the generic PM domains
framework.

First, the platform is expected to provide a cpuidle driver with one
extra state designated for use with the generic PM domains code.
This state should be initially disabled and its exit_latency value
should be set to whatever time is needed to bring up the CPU core
itself after restoring power to it, not including the domain's
power on latency.  Its .enter() callback should point to a procedure
that will remove power from the domain containing the CPU core at
the end of the CPU power transition.

The remaining characteristics of the extra cpuidle state, referred to
as the "domain" cpuidle state below, (e.g. power usage, target
residency) should be populated in accordance with the properties of
the hardware.

Next, the platform should execute genpd_attach_cpuidle() on the PM
domain containing the CPU core.  That will cause the generic PM
domains framework to treat that domain in a special way such that:

 * When all devices in the domain have been suspended and it is about
   to be turned off, the states of the devices will be saved, but
   power will not be removed from the domain.  Instead, the "domain"
   cpuidle state will be enabled so that power can be removed from
   the domain when the CPU core is idle and the state has been chosen
   as the target by the cpuidle governor.

 * When the first I/O device in the domain is resumed and
   __pm_genpd_poweron(() is called for the first time after
   power has been removed from the domain, the "domain" cpuidle
   state will be disabled to avoid subsequent surprise power removals
   via cpuidle.

The effective exit_latency value of the "domain" cpuidle state
depends on the time needed to bring up the CPU core itself after
restoring power to it as well as on the power on latency of the
domain containing the CPU core.  Thus the "domain" cpuidle state's
exit_latency has to be recomputed every time the domain's power on
latency is updated, which may happen every time power is restored
to the domain, if the measured power on latency is greater than
the latency stored in the corresponding generic_pm_domain structure.
Signed-off-by: NRafael J. Wysocki <rjw@sisk.pl>
Reviewed-by: NKevin Hilman <khilman@ti.com>

The generic PM domains core code currently requires domains to be in
the "power on" state for adding devices to them, but this limitation
turns out to be inconvenient in some situations, so remove it.

For this purpose, make __pm_genpd_add_device() set the device's
need_restore flag if the domain is in the "power off" state, so that
the device's "restore state" (usually .runtime_resume()) callback
is executed when it is resumed after the domain has been turned on.
If the domain is in the "power on" state, the device's need_restore
flag will be cleared by __pm_genpd_add_device(), so that its "save
state" (usually .runtime_suspend()) callback is executed when the
domain is about to be turned off.  However, since that default
behavior need not be always desirable, add a helper function
pm_genpd_dev_need_restore() allowing a device's need_restore flag
to be set/unset at any time.
Signed-off-by: NRafael J. Wysocki <rjw@sisk.pl>

The results of the default device stop and domain power off governor
functions for generic PM domains, default_stop_ok() and
default_power_down_ok(), depend only on the timing data of devices,
which are static, and on their PM QoS constraints.  Thus, in theory,
these functions only need to carry out their computations, which may
be time consuming in general, when it is known that the PM QoS
constraint of at least one of the devices in question has changed.

Use the PM QoS notifiers of devices to implement that.  First,
introduce new fields, constraint_changed and max_off_time_changed,
into struct gpd_timing_data and struct generic_pm_domain,
respectively, and register a PM QoS notifier function when adding
a device into a domain that will set those fields to 'true' whenever
the device's PM QoS constraint is modified.  Second, make
default_stop_ok() and default_power_down_ok() use those fields to
decide whether or not to carry out their computations from scratch.

The device and PM domain hierarchies are taken into account in that
and the expense is that the changes of PM QoS constraints of
suspended devices will not be taken into account immediately, which
isn't guaranteed anyway in general.
Signed-off-by: NRafael J. Wysocki <rjw@sisk.pl>

The existing default domain power down governor function for PM
domains, default_power_down_ok(), is supposed to check whether or not
the PM QoS latency constraints of the devices in the domain will be
violated if the domain is turned off by pm_genpd_poweroff().
However, the computations carried out by it don't reflect the
definition of the PM QoS latency constrait in
Documentation/ABI/testing/sysfs-devices-power.

Make default_power_down_ok() follow the definition of the PM QoS
latency constrait.  In particular, make it only take latencies into
account, because it doesn't matter how much time has elapsed since
the domain's devices were suspended for the computation.

Remove the break_even_ns and power_off_time fields from
struct generic_pm_domain, because they are not necessary any more.
Signed-off-by: NRafael J. Wysocki <rjw@sisk.pl>

The existing default device stop governor function for PM domains,
default_stop_ok(), is supposed to check whether or not the device's
PM QoS latency constraint will be violated if the device is stopped
by pm_genpd_runtime_suspend().  However, the computations carried out
by it don't reflect the definition of the PM QoS latency constrait in
Documentation/ABI/testing/sysfs-devices-power.

Make default_stop_ok() follow the definition of the PM QoS latency
constrait.  In particular, make it take the device's start and stop
latencies correctly.

Add a new field, effective_constraint_ns, to struct gpd_timing_data
and use it to store the difference between the device's PM QoS
constraint and its resume latency for use by the device's parent
(the effective_constraint_ns values for the children are used for
computing the parent's one along with its PM QoS constraint).

Remove the break_even_ns field from struct gpd_timing_data, because
it's not used any more.
Signed-off-by: NRafael J. Wysocki <rjw@sisk.pl>

The TMU device on the Mackerel board belongs to the A4R power domain
and loses power when the domain is turned off.  Unfortunately, the
TMU driver is not prepared to cope with such situations and crashes
the system when that happens.  To work around this problem introduce
a new helper function, pm_genpd_dev_always_on(), allowing a device
driver to mark its device as "always on" in case it belongs to a PM
domain, which will make the generic PM domains core code avoid
powering off the domain containing the device, both at run time and
during system suspend.
Signed-off-by: NRafael J. Wysocki <rjw@sisk.pl>
Tested-by: NSimon Horman <horms@verge.net.au>
Acked-by: NPaul Mundt <lethal@linux-sh.org>
Cc: stable@vger.kernel.org

The <linux/device.h> header includes a lot of stuff, and
it in turn gets a lot of use just for the basic "struct device"
which appears so often.

Clean up the users as follows:

1) For those headers only needing "struct device" as a pointer
in fcn args, replace the include with exactly that.

2) For headers not really using anything from device.h, simply
delete the include altogether.

3) For headers relying on getting device.h implicitly before
being included themselves, now explicitly include device.h

4) For files in which doing #1 or #2 uncovers an implicit
dependency on some other header, fix by explicitly adding
the required header(s).

Any C files that were implicitly relying on device.h to be
present have already been dealt with in advance.

Total removals from #1 and #2: 51.  Total additions coming
from #3: 9.  Total other implicit dependencies from #4: 7.

As of 3.3-rc1, there were 110, so a net removal of 42 gives
about a 38% reduction in device.h presence in include/*
Signed-off-by: NPaul Gortmaker <paul.gortmaker@windriver.com>

Fix pm_genpd_init() arguments and make sure dev_gpd_data() and
simple_qos_governor exist regardless of CONFIG_PM_GENERIC_DOMAINS
setting.
Signed-off-by: NMagnus Damm <damm@opensource.se>
Signed-off-by: NRafael J. Wysocki <rjw@sisk.pl>

dev_gpd_data() is a generic macro, also useful for drivers. Hence it should
be available also when CONFIG_PM_GENERIC_DOMAINS is not selected. OTOH,
to_gpd_data() is so far unused outside of the generic PM domain code and
does not seem to be very useful without CONFIG_PM_GENERIC_DOMAINS.
Signed-off-by: NGuennadi Liakhovetski <g.liakhovetski@gmx.de>
Signed-off-by: NRafael J. Wysocki <rjw@sisk.pl>

A device node pointer is added to generic pm domain structure to associate
the domain with a node in the device tree. The platform code parses the
device tree to find available nodes representing the generic power domain,
instantiates the available domains and initializes them by calling
pm_genpd_init().

Nodes representing the devices include a phandle of the power domain to
which it belongs. As these devices get instantiated, the driver code
checkes for availability of a power domain phandle, converts the phandle
to a device node and uses the new pm_genpd_of_add_device() api to
associate the device with a power domain.

pm_genpd_of_add_device() runs through its list of registered power domains
and matches the OF node of the domain with the one specified as the
parameter. If a match is found, the device is associated with the matched
domain.

Cc: Rob Herring <rob.herring@calxeda.com>
Cc: Grant Likely <grant.likely@secretlab.ca>
Signed-off-by: NThomas Abraham <thomas.abraham@linaro.org>
Acked-by: NRafael J. Wysocki <rjw@sisk.pl>
Signed-off-by: NKukjin Kim <kgene.kim@samsung.com>

Since systems are likely to have power domains that can't be turned off
for various reasons at least temporarily while implementing power domain
support provide a default governor which will always refuse to power off
the domain, saving platforms having to implement their own.

Since the code is so tiny don't bother with a Kconfig symbol for it.
Signed-off-by: NMark Brown <broonie@opensource.wolfsonmicro.com>
Signed-off-by: NRafael J. Wysocki <rjw@sisk.pl>

Add a name member pointer to struct generic_pm_domain and use it in
diagnostic messages regarding the domain power-off and power-on
latencies.  Update the ARM shmobile SH7372 code to assign names to
the PM domains used by it.
Signed-off-by: NRafael J. Wysocki <rjw@sisk.pl>
Acked-by: NMagnus Damm <damm@opensource.se>

Fix the following compalitaion breakage:

In file included from linux/drivers/sh/pm_runtime.c:15:
linux/include/linux/pm_domain.h: In function 'dev_to_genpd':
linux/include/linux/pm_domain.h:142: error: implicit declaration of function 'ERR_PTR'
linux/include/linux/pm_domain.h:142: warning: return makes pointer from integer without a cast
In file included from linux/include/linux/sh_clk.h:10,
                 from linux/drivers/sh/pm_runtime.c:19:
linux/include/linux/err.h: At top level:
linux/include/linux/err.h:22: error: conflicting types for 'ERR_PTR'
linux/include/linux/pm_domain.h:142: note: previous implicit declaration of 'ERR_PTR' was here
make[3]: *** [drivers/sh/pm_runtime.o] Error 1
Reported-by: NNobuhiro Iwamatsu <nobuhiro.iwamatsu.yj@renesas.com>
Signed-off-by: NGuennadi Liakhovetski <g.liakhovetski@gmx.de>
Signed-off-by: NRafael J. Wysocki <rjw@sisk.pl>

Add a function deciding whether or not a given PM domain should
be powered off on the basis of the PM QoS constraints of devices
belonging to it and their PM QoS timing data.
Signed-off-by: NRafael J. Wysocki <rjw@sisk.pl>

Add a function deciding whether or not devices should be stopped in
pm_genpd_runtime_suspend() depending on their PM QoS constraints
and stop/start timing values.  Make it possible to add information
used by this function to device objects.
Signed-off-by: NRafael J. Wysocki <rjw@sisk.pl>
Acked-by: NMagnus Damm <damm@opensource.se>

The current generic PM domains code attempts to use the generic
system suspend operations along with the domains' device stop/start
routines, which requires device drivers to assume that their
system suspend/resume (and hibernation/restore) callbacks will always
be used with generic PM domains.  However, in theory, the same
hardware may be used in devices that don't belong to any PM domain,
in which case it would be necessary to add "fake" PM domains to
satisfy the above assumption.  Also, the domain the hardware belongs
to may not be handled with the help of the generic code.

To allow device drivers that may be used along with the generic PM
domains code of more flexibility, add new device callbacks,
.suspend(), .suspend_late(), .resume_early(), .resume(), .freeze(),
.freeze_late(), .thaw_early(), and .thaw(), that can be supplied by
the drivers in addition to their "standard" system suspend and
hibernation callbacks.  These new callbacks, if defined, will be used
by the generic PM domains code for the handling of system suspend and
hibernation instead of the "standard" ones.  This will allow drivers
to be designed to work with generic PM domains as well as without
them.

For backwards compatibility, introduce default implementations of the
new callbacks for PM domains that will execute pm_generic_suspend(),
pm_generic_suspend_noirq(), pm_generic_resume_noirq(),
pm_generic_resume(), pm_generic_freeze(), pm_generic_freeze_noirq(),
pm_generic_thaw_noirq(), and pm_generic_thaw(), respectively, for the
given device if its driver doesn't define those callbacks.
Signed-off-by: NRafael J. Wysocki <rjw@sisk.pl>

The current PM domains code uses device drivers' .runtime_suspend()
and .runtime_resume() callbacks as the "save device state" and
"restore device state" operations, which may not be appropriate in
general, because it forces drivers to assume that they always will
be used with generic PM domains.  However, in theory, the same
hardware may be used in devices that don't belong to any PM
domain, in which case it would be necessary to add "fake" PM
domains to satisfy the above assumption.  It also may be located in
a PM domain that's not handled with the help of the generic code.

To allow device drivers that may be used along with the generic PM
domains code of more flexibility, introduce new device callbacks,
.save_state() and .restore_state(), that can be supplied by the
drivers in addition to their "standard" runtime PM callbacks.  This
will allow the drivers to be designed to work with generic PM domains
as well as without them.

For backwards compatibility, introduce default .save_state() and
.restore_state() callback routines for PM domains that will execute
a device driver's .runtime_suspend() and .runtime_resume() callbacks,
respectively, for the given device if the driver doesn't provide its
own implementations of .save_state() and .restore_state().
Signed-off-by: NRafael J. Wysocki <rjw@sisk.pl>

The current generic PM domains code requires that the same .stop(),
.start() and .active_wakeup() device callback routines be used for
all devices in the given domain, which is inflexible and may not
cover some specific use cases.  For this reason, make it possible to
use device specific .start()/.stop() and .active_wakeup() callback
routines by adding corresponding callback pointers to struct
generic_pm_domain_data.  Add a new helper routine,
pm_genpd_register_callbacks(), that can be used to populate
the new per-device callback pointers.

Modify the shmobile's power domains code to allow drivers to add
their own code to be run during the device stop and start operations
with the help of the new callback pointers.
Signed-off-by: NRafael J. Wysocki <rjw@sisk.pl>
Acked-by: NMagnus Damm <damm@opensource.se>

The struct pm_domain_data data type is defined in such a way that
adding new fields specific to the generic PM domains code will
require include/linux/pm.h to be modified.  As a result, data types
used only by the generic PM domains code will be defined in two
headers, although they all should be defined in pm_domain.h and
pm.h will need to include more headers, which won't be very nice.

For this reason change the definition of struct pm_subsys_data
so that its domain_data member is a pointer, which will allow
struct pm_domain_data to be subclassed by various PM domains
implementations.  Remove the need_restore member from
struct pm_domain_data and make the generic PM domains code
subclass it by adding the need_restore member to the new data type.
Signed-off-by: NRafael J. Wysocki <rjw@sisk.pl>

The generic PM domains framework currently doesn't work with devices
whose power.irq_safe flag is set, because runtime PM callbacks for
such devices are run with interrupts disabled and the callbacks
provided by the generic PM domains framework use domain mutexes
and may sleep.  However, such devices very well may belong to
power domains on some systems, so the generic PM domains framework
should take them into account.

For this reason, modify the generic PM domains framework so that the
domain .power_off() and .power_on() callbacks are never executed for
a domain containing devices with power.irq_safe set, although the
.stop_device() and .start_device() callbacks are still run for them.

Additionally, introduce a flag allowing the creator of a
struct generic_pm_domain object to indicate that its .stop_device()
and .start_device() callbacks may be run in interrupt context
(might_sleep_if() triggers if that flag is not set and one of those
callbacks is run in interrupt context).
Signed-off-by: NRafael J. Wysocki <rjw@sisk.pl>

Currently pm_genpd_runtime_resume() has to walk the list of devices
from the device's PM domain to find the corresponding device list
object containing the need_restore field to check if the driver's
.runtime_resume() callback should be executed for the device.
This is suboptimal and can be simplified by using power.sybsys_data
to store device information used by the generic PM domains code.
Signed-off-by: NRafael J. Wysocki <rjw@sisk.pl>

Since it is now possible for a PM domain to have multiple masters
instead of one parent, rename the "wait for parent" status to reflect
the new situation.
Signed-off-by: NRafael J. Wysocki <rjw@sisk.pl>

Currently, for a given generic PM domain there may be only one parent
domain (i.e. a PM domain it depends on).  However, there is at least
one real-life case in which there should be two parents (masters) for
one PM domain (the A3RV domain on SH7372 turns out to depend on the
A4LC domain and it depends on the A4R domain and the same time). For
this reason, allow a PM domain to have multiple parents (masters) by
introducing objects representing links between PM domains.

The (logical) links between PM domains represent relationships in
which one domain is a master (i.e. it is depended on) and another
domain is a slave (i.e. it depends on the master) with the rule that
the slave cannot be powered on if the master is not powered on and
the master cannot be powered off if the slave is not powered off.
Each struct generic_pm_domain object representing a PM domain has
two lists of links, a list of links in which it is a master and
a list of links in which it is a slave.  The first of these lists
replaces the list of subdomains and the second one is used in place
of the parent pointer.

Each link is represented by struct gpd_link object containing
pointers to the master and the slave and two struct list_head
members allowing it to hook into two lists (the master's list
of "master" links and the slave's list of "slave" links).  This
allows the code to get to the link from each side (either from
the master or from the slave) and follow it in each direction.
Signed-off-by: NRafael J. Wysocki <rjw@sisk.pl>

The next patch will make it possible for a generic PM domain to have
multiple parents (i.e. multiple PM domains it depends on).  To
prepare for that change it is necessary to change pm_genpd_poweron()
so that it doesn't jump to the start label after running itself
recursively for the parent domain.  For this purpose, introduce a new
PM domain status value GPD_STATE_WAIT_PARENT that will be set by
pm_genpd_poweron() before calling itself recursively for the parent
domain and modify the code in drivers/base/power/domain.c so that
the GPD_STATE_WAIT_PARENT status is guaranteed to be preserved during
the execution of pm_genpd_poweron() for the parent.

This change also causes pm_genpd_add_subdomain() and
pm_genpd_remove_subdomain() to wait for started pm_genpd_poweron() to
complete and allows pm_genpd_runtime_resume() to avoid dropping the
lock after powering on the PM domain.
Signed-off-by: NRafael J. Wysocki <rjw@sisk.pl>

Currently, pm_genpd_poweron() and pm_genpd_poweroff() need to take
the parent PM domain's lock in order to modify the parent's counter
of active subdomains in a nonracy way.  This causes the locking to be
considerably complex and in fact is not necessary, because the
subdomain counters may be implemented as atomic fields and they
won't have to be modified under a lock.

Replace the unsigned in sd_count field in struct generic_pm_domain
by an atomic_t one and modify the code in drivers/base/power/domain.c
to take this change into account.

This patch doesn't change the locking yet, that is going to be done
in a separate subsequent patch.
Signed-off-by: NRafael J. Wysocki <rjw@sisk.pl>

Function genpd_queue_power_off_work() is not defined for
CONFIG_PM_RUNTIME, so pm_genpd_poweroff_unused() causes a build
error to happen in that case.  Fix the problem by making
pm_genpd_poweroff_unused() depend on CONFIG_PM_RUNTIME too.
Signed-off-by: NRafael J. Wysocki <rjw@sisk.pl>

Make pd_power_down_a3rv() use genpd_queue_power_off_work() to queue
up the powering off of the A4LC domain to avoid queuing it up when
it is pending.
Signed-off-by: NRafael J. Wysocki <rjw@sisk.pl>
Acked-by: NMagnus Damm <damm@opensource.se>

Add a new function pm_genpd_poweroff_unused() queuing up the
execution of pm_genpd_poweroff() for every initialized generic PM
domain.  Calling it will cause every generic PM domain without
devices in use to be powered off.
Signed-off-by: NRafael J. Wysocki <rjw@sisk.pl>
Acked-by: NMagnus Damm <damm@opensource.se>

A deadlock may occur if one of the PM domains' .start_device() or
.stop_device() callbacks or a device driver's .runtime_suspend() or
.runtime_resume() callback executed by the core generic PM domain
code uses a "wrong" runtime PM helper function.  This happens, for
example, if .runtime_resume() from one device's driver calls
pm_runtime_resume() for another device in the same PM domain.
A similar situation may take place if a device's parent is in the
same PM domain, in which case the runtime PM framework may execute
pm_genpd_runtime_resume() automatically for the parent (if it is
suspended at the moment).  This, of course, is undesirable, so
the generic PM domains code should be modified to prevent it from
happening.

The runtime PM framework guarantees that pm_genpd_runtime_suspend()
and pm_genpd_runtime_resume() won't be executed in parallel for
the same device, so the generic PM domains code need not worry
about those cases.  Still, it needs to prevent the other possible
race conditions between pm_genpd_runtime_suspend(),
pm_genpd_runtime_resume(), pm_genpd_poweron() and pm_genpd_poweroff()
from happening and it needs to avoid deadlocks at the same time.
To this end, modify the generic PM domains code to relax
synchronization rules so that:

* pm_genpd_poweron() doesn't wait for the PM domain status to
  change from GPD_STATE_BUSY.  If it finds that the status is
  not GPD_STATE_POWER_OFF, it returns without powering the domain on
  (it may modify the status depending on the circumstances).

* pm_genpd_poweroff() returns as soon as it finds that the PM
  domain's status changed from GPD_STATE_BUSY after it's released
  the PM domain's lock.

* pm_genpd_runtime_suspend() doesn't wait for the PM domain status
  to change from GPD_STATE_BUSY after executing the domain's
  .stop_device() callback and executes pm_genpd_poweroff() only
  if pm_genpd_runtime_resume() is not executed in parallel.

* pm_genpd_runtime_resume() doesn't wait for the PM domain status
  to change from GPD_STATE_BUSY after executing pm_genpd_poweron()
  and sets the domain's status to GPD_STATE_BUSY and increments its
  counter of resuming devices (introduced by this change) immediately
  after acquiring the lock.  The counter of resuming devices is then
  decremented after executing __pm_genpd_runtime_resume() for the
  device and the domain's status is reset to GPD_STATE_ACTIVE (unless
  there are more resuming devices in the domain, in which case the
  status remains GPD_STATE_BUSY).

This way, for example, if a device driver's .runtime_resume()
callback executes pm_runtime_resume() for another device in the same
PM domain, pm_genpd_poweron() called by pm_genpd_runtime_resume()
invoked by the runtime PM framework will not block and it will see
that there's nothing to do for it.  Next, the PM domain's lock will
be acquired without waiting for its status to change from
GPD_STATE_BUSY and the device driver's .runtime_resume() callback
will be executed.  In turn, if pm_runtime_suspend() is executed by
one device driver's .runtime_resume() callback for another device in
the same PM domain, pm_genpd_poweroff() executed by
pm_genpd_runtime_suspend() invoked by the runtime PM framework as a
result will notice that one of the devices in the domain is being
resumed, so it will return immediately.
Signed-off-by: NRafael J. Wysocki <rjw@sisk.pl>

Currently, the .start_device() and .stop_device() callbacks from
struct generic_pm_domain() as well as the device drivers' runtime PM
callbacks used by the generic PM domains code are executed under
the generic PM domain lock.  This, unfortunately, is prone to
deadlocks, for example if a device and its parent are boths members
of the same PM domain.  For this reason, it would be better if the
PM domains code didn't execute device callbacks under the lock.

Rework the locking in the generic PM domains code so that the lock
is dropped for the execution of device callbacks.  To this end,
introduce PM domains states reflecting the current status of a PM
domain and such that the PM domain lock cannot be acquired if the
status is GPD_STATE_BUSY.  Make threads attempting to acquire a PM
domain's lock wait until the status changes to either
GPD_STATE_ACTIVE or GPD_STATE_POWER_OFF.

This change by itself doesn't fix the deadlock problem mentioned
above, but the mechanism introduced by it will be used for for this
purpose by a subsequent patch.
Signed-off-by: NRafael J. Wysocki <rjw@sisk.pl>

Allow SoC-specific code to call pm_genpd_poweron().
Signed-off-by: NMagnus Damm <damm@opensource.se>
Signed-off-by: NRafael J. Wysocki <rjw@sisk.pl>

There is the problem how to handle devices set up to wake up the
system from sleep states during system-wide power transitions.
In some cases, those devices can be turned off entirely, because the
wakeup signals will be generated on their behalf anyway.  In some
other cases, they will generate wakeup signals if their clocks are
stopped, but only if power is not removed from them.  Finally, in
some cases, they can only generate wakeup signals if power is not
removed from them and their clocks are enabled.

To allow platform-specific code to decide whether or not to put
wakeup devices (and their PM domains) into low-power state during
system-wide transitions, such as system suspend, introduce a new
generic PM domain callback, .active_wakeup(), that will be used
during the "noirq" phase of system suspend and hibernation (after
image creation) to decide what to do with wakeup devices.
Specifically, if this callback is present and returns "true", the
generic PM domain code will not execute .stop_device() for the
given wakeup device and its PM domain won't be powered off.
Signed-off-by: NRafael J. Wysocki <rjw@sisk.pl>
Acked-by: NKevin Hilman <khilman@ti.com>

Make generic PM domains support system-wide power transitions
(system suspend and hibernation).  Add suspend, resume, freeze, thaw,
poweroff and restore callbacks to be associated with struct
generic_pm_domain objects and make pm_genpd_init() use them as
appropriate.

The new callbacks do nothing for devices belonging to power domains
that were powered down at run time (before the transition).  For the
other devices the action carried out depends on the type of the
transition.  During system suspend the power domain .suspend()
callback executes pm_generic_suspend() for the device, while the
PM domain .suspend_noirq() callback runs pm_generic_suspend_noirq()
for it, stops it and eventually removes power from the PM domain it
belongs to (after all devices in the domain have been stopped and its
subdomains have been powered off).

During system resume the PM domain .resume_noirq() callback
restores power to the PM domain (when executed for it first time),
starts the device and executes pm_generic_resume_noirq() for it,
while the .resume() callback executes pm_generic_resume() for the
device.  Finally, the .complete() callback executes pm_runtime_idle()
for the device which should put it back into the suspended state if
its runtime PM usage count is equal to zero at that time.

The actions carried out during hibernation and resume from it are
analogous to the ones described above.
Signed-off-by: NRafael J. Wysocki <rjw@sisk.pl>
Reviewed-by: NKevin Hilman <khilman@ti.com>

Introduce common headers, helper functions and callbacks allowing
platforms to use simple generic power domains for runtime power
management.

Introduce struct generic_pm_domain to be used for representing
power domains that each contain a number of devices and may be
parent domains or subdomains with respect to other power domains.
Among other things, this structure includes callbacks to be
provided by platforms for performing specific tasks related to
power management (i.e. ->stop_device() may disable a device's
clocks, while ->start_device() may enable them, ->power_off() is
supposed to remove power from the entire power domain
and ->power_on() is supposed to restore it).

Introduce functions that can be used as power domain runtime PM
callbacks, pm_genpd_runtime_suspend() and pm_genpd_runtime_resume(),
as well as helper functions for the initialization of a power
domain represented by a struct generic_power_domain object,
adding a device to or removing a device from it and adding or
removing subdomains.

Introduce configuration option CONFIG_PM_GENERIC_DOMAINS to be
selected by the platforms that want to use the new code.
Signed-off-by: NRafael J. Wysocki <rjw@sisk.pl>
Acked-by: NGreg Kroah-Hartman <gregkh@suse.de>
Reviewed-by: NKevin Hilman <khilman@ti.com>