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regulator: sysfs attribute reduction (v2)
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Clean up the sysfs interface to regulators by only exposing the
attributes that can be properly displayed.  For example: when a
particular regulator method is needed to display the value, only
create that attribute when that method exists.

This cleaned-up interface is much more comprehensible.  Most
regulators only support a subset of the possible methods, so
often more than half the attributes would be meaningless.  Many
"not defined" values are no longer necessary.  (But handling
of out-of-range values still looks a bit iffy.)

Documentation is updated to reflect that few of the attributes
are *always* present, and to briefly explain why a regulator may
not have a given attribute.

This adds object code, about a dozen bytes more than was removed
by the preceding patch, but saves a bunch of per-regulator data
associated with the now-removed attributes.  So there's a net
reduction in memory footprint.

Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: Liam Girdwood <lrg@slimlogic.co.uk>
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David Brownell authored and Liam Girdwood committed Jan 8, 2009
1 parent 4fca954 commit 7ad68e2
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136 changes: 60 additions & 76 deletions Documentation/ABI/testing/sysfs-class-regulator
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Original file line number Diff line number Diff line change
Expand Up @@ -3,8 +3,9 @@ Date: April 2008
KernelVersion: 2.6.26
Contact: Liam Girdwood <lrg@slimlogic.co.uk>
Description:
Each regulator directory will contain a field called
state. This holds the regulator output state.
Some regulator directories will contain a field called
state. This reports the regulator enable status, for
regulators which can report that value.

This will be one of the following strings:

Expand All @@ -18,7 +19,8 @@ Description:
'disabled' means the regulator output is OFF and is not
supplying power to the system..

'unknown' means software cannot determine the state.
'unknown' means software cannot determine the state, or
the reported state is invalid.

NOTE: this field can be used in conjunction with microvolts
and microamps to determine regulator output levels.
Expand Down Expand Up @@ -53,9 +55,10 @@ Date: April 2008
KernelVersion: 2.6.26
Contact: Liam Girdwood <lrg@slimlogic.co.uk>
Description:
Each regulator directory will contain a field called
Some regulator directories will contain a field called
microvolts. This holds the regulator output voltage setting
measured in microvolts (i.e. E-6 Volts).
measured in microvolts (i.e. E-6 Volts), for regulators
which can report that voltage.

NOTE: This value should not be used to determine the regulator
output voltage level as this value is the same regardless of
Expand All @@ -67,9 +70,10 @@ Date: April 2008
KernelVersion: 2.6.26
Contact: Liam Girdwood <lrg@slimlogic.co.uk>
Description:
Each regulator directory will contain a field called
Some regulator directories will contain a field called
microamps. This holds the regulator output current limit
setting measured in microamps (i.e. E-6 Amps).
setting measured in microamps (i.e. E-6 Amps), for regulators
which can report that current.

NOTE: This value should not be used to determine the regulator
output current level as this value is the same regardless of
Expand All @@ -81,8 +85,9 @@ Date: April 2008
KernelVersion: 2.6.26
Contact: Liam Girdwood <lrg@slimlogic.co.uk>
Description:
Each regulator directory will contain a field called
opmode. This holds the regulator operating mode setting.
Some regulator directories will contain a field called
opmode. This holds the current regulator operating mode,
for regulators which can report it.

The opmode value can be one of the following strings:

Expand All @@ -92,7 +97,7 @@ Description:
'standby'
'unknown'

The modes are described in include/linux/regulator/regulator.h
The modes are described in include/linux/regulator/consumer.h

NOTE: This value should not be used to determine the regulator
output operating mode as this value is the same regardless of
Expand All @@ -104,9 +109,10 @@ Date: April 2008
KernelVersion: 2.6.26
Contact: Liam Girdwood <lrg@slimlogic.co.uk>
Description:
Each regulator directory will contain a field called
Some regulator directories will contain a field called
min_microvolts. This holds the minimum safe working regulator
output voltage setting for this domain measured in microvolts.
output voltage setting for this domain measured in microvolts,
for regulators which support voltage constraints.

NOTE: this will return the string 'constraint not defined' if
the power domain has no min microvolts constraint defined by
Expand All @@ -118,9 +124,10 @@ Date: April 2008
KernelVersion: 2.6.26
Contact: Liam Girdwood <lrg@slimlogic.co.uk>
Description:
Each regulator directory will contain a field called
Some regulator directories will contain a field called
max_microvolts. This holds the maximum safe working regulator
output voltage setting for this domain measured in microvolts.
output voltage setting for this domain measured in microvolts,
for regulators which support voltage constraints.

NOTE: this will return the string 'constraint not defined' if
the power domain has no max microvolts constraint defined by
Expand All @@ -132,10 +139,10 @@ Date: April 2008
KernelVersion: 2.6.26
Contact: Liam Girdwood <lrg@slimlogic.co.uk>
Description:
Each regulator directory will contain a field called
Some regulator directories will contain a field called
min_microamps. This holds the minimum safe working regulator
output current limit setting for this domain measured in
microamps.
microamps, for regulators which support current constraints.

NOTE: this will return the string 'constraint not defined' if
the power domain has no min microamps constraint defined by
Expand All @@ -147,10 +154,10 @@ Date: April 2008
KernelVersion: 2.6.26
Contact: Liam Girdwood <lrg@slimlogic.co.uk>
Description:
Each regulator directory will contain a field called
Some regulator directories will contain a field called
max_microamps. This holds the maximum safe working regulator
output current limit setting for this domain measured in
microamps.
microamps, for regulators which support current constraints.

NOTE: this will return the string 'constraint not defined' if
the power domain has no max microamps constraint defined by
Expand Down Expand Up @@ -185,7 +192,7 @@ Date: April 2008
KernelVersion: 2.6.26
Contact: Liam Girdwood <lrg@slimlogic.co.uk>
Description:
Each regulator directory will contain a field called
Some regulator directories will contain a field called
requested_microamps. This holds the total requested load
current in microamps for this regulator from all its consumer
devices.
Expand All @@ -204,125 +211,102 @@ Date: May 2008
KernelVersion: 2.6.26
Contact: Liam Girdwood <lrg@slimlogic.co.uk>
Description:
Each regulator directory will contain a field called
Some regulator directories will contain a field called
suspend_mem_microvolts. This holds the regulator output
voltage setting for this domain measured in microvolts when
the system is suspended to memory.

NOTE: this will return the string 'not defined' if
the power domain has no suspend to memory voltage defined by
platform code.
the system is suspended to memory, for voltage regulators
implementing suspend voltage configuration constraints.

What: /sys/class/regulator/.../suspend_disk_microvolts
Date: May 2008
KernelVersion: 2.6.26
Contact: Liam Girdwood <lrg@slimlogic.co.uk>
Description:
Each regulator directory will contain a field called
Some regulator directories will contain a field called
suspend_disk_microvolts. This holds the regulator output
voltage setting for this domain measured in microvolts when
the system is suspended to disk.

NOTE: this will return the string 'not defined' if
the power domain has no suspend to disk voltage defined by
platform code.
the system is suspended to disk, for voltage regulators
implementing suspend voltage configuration constraints.

What: /sys/class/regulator/.../suspend_standby_microvolts
Date: May 2008
KernelVersion: 2.6.26
Contact: Liam Girdwood <lrg@slimlogic.co.uk>
Description:
Each regulator directory will contain a field called
Some regulator directories will contain a field called
suspend_standby_microvolts. This holds the regulator output
voltage setting for this domain measured in microvolts when
the system is suspended to standby.

NOTE: this will return the string 'not defined' if
the power domain has no suspend to standby voltage defined by
platform code.
the system is suspended to standby, for voltage regulators
implementing suspend voltage configuration constraints.

What: /sys/class/regulator/.../suspend_mem_mode
Date: May 2008
KernelVersion: 2.6.26
Contact: Liam Girdwood <lrg@slimlogic.co.uk>
Description:
Each regulator directory will contain a field called
Some regulator directories will contain a field called
suspend_mem_mode. This holds the regulator operating mode
setting for this domain when the system is suspended to
memory.

NOTE: this will return the string 'not defined' if
the power domain has no suspend to memory mode defined by
platform code.
memory, for regulators implementing suspend mode
configuration constraints.

What: /sys/class/regulator/.../suspend_disk_mode
Date: May 2008
KernelVersion: 2.6.26
Contact: Liam Girdwood <lrg@slimlogic.co.uk>
Description:
Each regulator directory will contain a field called
Some regulator directories will contain a field called
suspend_disk_mode. This holds the regulator operating mode
setting for this domain when the system is suspended to disk.

NOTE: this will return the string 'not defined' if
the power domain has no suspend to disk mode defined by
platform code.
setting for this domain when the system is suspended to disk,
for regulators implementing suspend mode configuration
constraints.

What: /sys/class/regulator/.../suspend_standby_mode
Date: May 2008
KernelVersion: 2.6.26
Contact: Liam Girdwood <lrg@slimlogic.co.uk>
Description:
Each regulator directory will contain a field called
Some regulator directories will contain a field called
suspend_standby_mode. This holds the regulator operating mode
setting for this domain when the system is suspended to
standby.

NOTE: this will return the string 'not defined' if
the power domain has no suspend to standby mode defined by
platform code.
standby, for regulators implementing suspend mode
configuration constraints.

What: /sys/class/regulator/.../suspend_mem_state
Date: May 2008
KernelVersion: 2.6.26
Contact: Liam Girdwood <lrg@slimlogic.co.uk>
Description:
Each regulator directory will contain a field called
Some regulator directories will contain a field called
suspend_mem_state. This holds the regulator operating state
when suspended to memory.

This will be one of the following strings:
when suspended to memory, for regulators implementing suspend
configuration constraints.

'enabled'
'disabled'
'not defined'
This will be one of the same strings reported by
the "state" attribute.

What: /sys/class/regulator/.../suspend_disk_state
Date: May 2008
KernelVersion: 2.6.26
Contact: Liam Girdwood <lrg@slimlogic.co.uk>
Description:
Each regulator directory will contain a field called
Some regulator directories will contain a field called
suspend_disk_state. This holds the regulator operating state
when suspended to disk.

This will be one of the following strings:
when suspended to disk, for regulators implementing
suspend configuration constraints.

'enabled'
'disabled'
'not defined'
This will be one of the same strings reported by
the "state" attribute.

What: /sys/class/regulator/.../suspend_standby_state
Date: May 2008
KernelVersion: 2.6.26
Contact: Liam Girdwood <lrg@slimlogic.co.uk>
Description:
Each regulator directory will contain a field called
Some regulator directories will contain a field called
suspend_standby_state. This holds the regulator operating
state when suspended to standby.

This will be one of the following strings:
state when suspended to standby, for regulators implementing
suspend configuration constraints.

'enabled'
'disabled'
'not defined'
This will be one of the same strings reported by
the "state" attribute.
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