sh: MTU2: Basic runtime PM support

Modify the SH MTU2 clock event device driver to support runtime PM at
a basic level (i.e. device clocks can be disabled and enabled, but
domain power must be on, because the device has to be marked as
"irq safe").

Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
Acked-by: Magnus Damm <damm@opensource.se>
PM: Do not use the syscore flag for runtime PM

The syscore device PM flag used to mark the devices (belonging to
PM domains) that should never be turned off, except for the system
core (syscore) suspend/hibernation and resume stages, need not be
accessed by the runtime PM core functions, because all of the devices
it is set for need to be marked as "irq safe" anyway and are
protected from being turned off by runtime PM by ensuring that their
usage counters are always set.

For this reason, make the syscore flag system-wide PM-specific
and simplify the code used for manipulating it, because it need not
acquire the device's power.lock any more.

Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
PM / Domains: Make it possible to use domain names when adding devices

Add a new helper function __pm_genpd_name_add_device() allowing
a device to be added to a (registered) generic PM domain identified
by name.  Add a wrapper around it, pm_genpd_name_add_device(),
passing NULL as the last argument and reorganize pm_domains.h for the
new functions to be defined consistently with the existing ones.

These functions are useful for adding devices to PM domains whose
representations are stored in tables, when the caller doesn't know
the index of the domain to add the device to, but it knows the
domain's name.

Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
ARM: shmobile: Use names of power domains for adding devices to them

Make the power management code under arch/arm/mach-shmobile/ use
names of power domains instead of pointers to domain objects for
adding devices to the domains.  This will allow us to put the
domain objects into tables and register them all in one shot
going forward.

Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
Acked-by: Magnus Damm <damm@opensource.se>
ARM: shmobile: Drop r8a7779_add_device_to_domain()

If the r8a7779's PM domains are given names, this SoC and its boards
will be able to use rmobile_add_device_to_domain() for adding devices
to those domains and r8a7779_add_device_to_domain(), which is not
used anywhere at the moment anyway, may be dopped.

Accordingly, give names to the r8a7779's PM domains and drop
r8a7779_add_device_to_domain().

Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
Acked-by: Magnus Damm <damm@opensource.se>
PM / Domains: Make it possible to use names when adding subdomains

Add a new helper function, pm_genpd_add_subdomain_names(), allowing
the caller to add a subdomain to a generic PM domain using names for
domain identification (both domains have to be initialized before).

This function is useful for adding subdomains to PM domains whose
representations are stored in tables, when the caller doesn't know
the indices of the domain to add the subdomain to and of the
subdomain itself, but it knows the domains' names.

Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
ARM: shmobile: Use domain names when adding subdomains to power domains

Make the power management code under arch/arm/mach-shmobile/
use pm_genpd_add_subdomain_names() for adding subdomains to power
domains, which makes it possible to drop
rmobile_pm_add_subdomain() and will allow us to carry out those
operations for domain objects stored in tables in a straightforward
way.

Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
Acked-by: Magnus Damm <damm@opensource.se>
ARM: shmobile: Add routine for automatic PM domains initialization

Add a new routine, rmobile_init_domains(), allowing the caller
to initialize all generic PM objects stored in a table in one
operation.

Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
Acked-by: Magnus Damm <damm@opensource.se>
PM / Domains: Add power-on function using names to identify domains

It sometimes is necessary to turn on a given PM domain when only
the name of it is known and the domain pointer is not readily
available.  For this reason, add a new helper function,
pm_genpd_name_poweron(), allowing the caller to turn on a PM domain
using its name for identification.  To avoid code duplication,
move the domain lookup code to a separate function.

Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
PM / shmobile: Do not access sh7372 A4S domain internals directly

The sh7372_enter_suspend() routine checks the status field of the
generic PM domain object corresponding to the A4S domain in order to
check if it can turn that domain off when entering system sleep.
However, it shouldn't rely on the specific values of the generic
data structures this way, so make it use its own mechanism to
recognize when it is safe to turn that domain off.

For this purpose, introduce a boolean variable a4s_suspend_ready
that will be set by the A4S' suspend routine and unset by its
resume routine executed by rmobile_pd_power_down() and
__rmobile_pd_power_up(), respectively.

Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
Acked-by: Magnus Damm <damm@opensource.se>
ARM: shmobile: Move sh7372's PM domain objects to a table

Instead of giving a name to every sh7372's PM domain object, put them
all into a table and use rmobile_init_domains(), introduced by a
previous patch, for initializing them all altogether.  Also, use
pm_genpd_add_subdomain_names() for adding subdomains to the PM
domains and pm_genpd_poweron_name() for turning on the A4S domain
when preparing for system suspend.

Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
Acked-by: Magnus Damm <damm@opensource.se>
ARM: shmobile: Move r8a7740's PM domain objects to a table

Instead of giving a name to every r8a7740's PM domain object, put
them all into a table and use rmobile_init_domains(), introduced by a
previous patch, for initializing them all altogether.  Also, use
pm_genpd_add_subdomain_names() for adding A3SP as a subdomain of A4S.

Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
Acked-by: Magnus Damm <damm@opensource.se>
ARM: shmobile: Move r8a7779's PM domain objects to a table

Instead of giving a name to every r8a7779's PM domain object, put
them all into a table and initialize them all together in a loop.

Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
Acked-by: Magnus Damm <damm@opensource.se>
ARM: shmobile: Make rmobile_init_pm_domain() static

Since rmobile_init_pm_domain() is not called anywhere outside of
arch/arm/mach-shmobile/pm-rmobile.c any more, it can be made static
and its header may be removed from pm-rmobile.h.  Modify the code
accordingly.

Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
Acked-by: Magnus Damm <damm@opensource.se>
PM / shmobile: Set PM domain on/off latencies directly

The results of adaptive latency computations in __pm_genpd_poweron()
and pm_genpd_poweroff() show that the power on/power off latencies
of all power domains in SH7372 are a little below 250 us.  Therefore,
if 250 us is used as the common initial value of the latency fields
in struct generic_pm_domain for all domains, the latency values
will never have to change at run time and there won't be any overhead
related to re-computation of the corresponding PM QoS data.

Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
Acked-by: Magnus Damm <damm@opensource.se>
PM / shmobile: Allow device latencies to be specified directly

Make it possible to specify device start/stop and save/restore
state latencies directy when adding devices to PM domains.  For
this purpose, introduce rmobile_add_device_to_domain_td() whose
third argument is a pointer to a struct gpd_timing_data object
containing device latency data.

Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
Acked-by: Magnus Damm <damm@opensource.se>
PM / shmobile: Specify device latencies for SH7372 devices directly

The results of adaptive latency computations in
GENPD_DEV_TIMED_CALLBACK() show that the start/stop and save/restore
state latencies of all devices on SH7372 I have tried are a little
below 250 us.  Therefore, if the 250 us is used as the common initial
value of the latency fields in struct gpd_timing_data for all devices
on SH7372, the latency values will never have to change at run time
and there won't be any overhead related to re-computation of the
corresponding PM QoS data.

Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
Acked-by: Magnus Damm <damm@opensource.se>
PM / shmobile: Specify device latencies for Mackerel devices directly

The results of adaptive latency computations in
GENPD_DEV_TIMED_CALLBACK() show that the start/stop and save/restore
state latencies of all devices on the Mackerel board I have tried are
a little below 250 us.  Therefore, if the 250 us is used as the
common initial value of the latency fields in struct gpd_timing_data
for all devices on Mackerel, the latency values will never have to
change at run time and there won't be any overhead related to
re-computation of the corresponding PM QoS data.

Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
Acked-by: Magnus Damm <damm@opensource.se>
Merge branch 'pm-shmobile-next' into linux-next

* pm-shmobile-next:
  PM / shmobile: Specify device latencies for Mackerel devices directly
  PM / shmobile: Specify device latencies for SH7372 devices directly
  PM / shmobile: Allow device latencies to be specified directly
  PM / shmobile: Set PM domain on/off latencies directly
  ARM: shmobile: Make rmobile_init_pm_domain() static
  ARM: shmobile: Move r8a7779's PM domain objects to a table
  ARM: shmobile: Move r8a7740's PM domain objects to a table
  ARM: shmobile: Move sh7372's PM domain objects to a table
  PM / shmobile: Do not access sh7372 A4S domain internals directly
  PM / Domains: Add power-on function using names to identify domains
  ARM: shmobile: Add routine for automatic PM domains initialization
  ARM: shmobile: Use domain names when adding subdomains to power domains
  PM / Domains: Make it possible to use names when adding subdomains
  ARM: shmobile: Drop r8a7779_add_device_to_domain()
  ARM: shmobile: Use names of power domains for adding devices to them
  PM / Domains: Make it possible to use domain names when adding devices
  PM: Do not use the syscore flag for runtime PM
  sh: MTU2: Basic runtime PM support
Honor state disabling in the cpuidle ladder governor

There are two cpuidle governors ladder and menu. While the ladder
governor is always available, if CONFIG_CPU_IDLE is selected, the
menu governor additionally requires CONFIG_NO_HZ.

A particular C state can be disabled by writing to the sysfs file
/sys/devices/system/cpu/cpuN/cpuidle/stateN/disable, but this mechanism
is only implemented in the menu governor. Thus, in a system where
CONFIG_NO_HZ is not selected, the ladder governor becomes default and
always will walk through all sleep states - irrespective of whether the
C state was disabled via sysfs or not. The only way to select a specific
C state was to write the related latency to /dev/cpu_dma_latency and
keep the file open as long as this setting was required - not very
practical and not suitable for setting a single core in an SMP system.

With this patch, the ladder governor only will promote to the next
C state, if it has not been disabled, and it will demote, if the
current C state was disabled.

Note that the patch does not make the setting of the sysfs variable
"disable" coherent, i.e. if one is disabling a light state, then all
deeper states are disabled as well, but the "disable" variable does not
reflect it. Likewise, if one enables a deep state but a lighter state
still is disabled, then this has no effect. A related section has been
added to the documentation.

Signed-off-by: Carsten Emde <C.Emde@osadl.org>
Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>