regulator: sysfs attribute reduction (v2)

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>

1 files changed, 60 insertions, 76 deletions

diff --git a/Documentation/ABI/testing/sysfs-class-regulator b/Documentation/ABI/testing/sysfs-class-regulator
index 3731f6f29bcb..873ef1fc1569 100644
--- a/Documentation/ABI/testing/sysfs-class-regulator
+++ b/Documentation/ABI/testing/sysfs-class-regulator
@@ -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:
 
@@ -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.
@@ -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
@@ -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
@@ -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:
 
@@ -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
@@ -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
@@ -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
@@ -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
@@ -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
@@ -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.
@@ -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.