From: David Brownell

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
---
Difference from V1: update the sysfs ABI/testing docs to match.

Documentation/ABI/testing/sysfs-class-regulator | 136 ++++++---------
drivers/regulator/core.c | 196 ++++++++++++++++------
2 files changed, 208 insertions(+), 124 deletions(-)

--- 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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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.
--- a/drivers/regulator/core.c
+++ b/drivers/regulator/core.c
@@ -232,6 +232,7 @@ static ssize_t regulator_uV_show(struct

return ret;
}
+static DEVICE_ATTR(microvolts, 0444, regulator_uV_show, NULL);

static ssize_t regulator_uA_show(struct device *dev,
struct device_attribute *attr, char *buf)
@@ -240,6 +241,7 @@ static ssize_t regulator_uA_show(struct

return sprintf(buf, "%d\n", _regulator_get_current_limit(rdev));
}
+static DEVICE_ATTR(microamps, 0444, regulator_uA_show, NULL);

static ssize_t regulator_name_show(struct device *dev,
struct device_attribute *attr, char *buf)
@@ -279,6 +281,7 @@ static ssize_t regulator_opmode_show(str

return regulator_print_opmode(buf, _regulator_get_mode(rdev));
}
+static DEVICE_ATTR(opmode, 0444, regulator_opmode_show, NULL);

static ssize_t regulator_print_state(char *buf, int state)
{
@@ -297,6 +300,7 @@ static ssize_t regulator_state_show(stru

return regulator_print_state(buf, _regulator_is_enabled(rdev));
}
+static DEVICE_ATTR(state, 0444, regulator_state_show, NULL);

static ssize_t regulator_min_uA_show(struct device *dev,
struct device_attribute *attr, char *buf)
@@ -308,6 +312,7 @@ static ssize_t regulator_min_uA_show(str

return sprintf(buf, "%d\n", rdev->constraints->min_uA);
}
+static DEVICE_ATTR(min_microamps, 0444, regulator_min_uA_show, NULL);

static ssize_t regulator_max_uA_show(struct device *dev,
struct device_attribute *attr, char *buf)
@@ -319,6 +324,7 @@ static ssize_t regulator_max_uA_show(str

return sprintf(buf, "%d\n", rdev->constraints->max_uA);
}
+static DEVICE_ATTR(max_microamps, 0444, regulator_max_uA_show, NULL);

static ssize_t regulator_min_uV_show(struct device *dev,
struct device_attribute *attr, char *buf)
@@ -330,6 +336,7 @@ static ssize_t regulator_min_uV_show(str

return sprintf(buf, "%d\n", rdev->constraints->min_uV);
}
+static DEVICE_ATTR(min_microvolts, 0444, regulator_min_uV_show, NULL);

static ssize_t regulator_max_uV_show(struct device *dev,
struct device_attribute *attr, char *buf)
@@ -341,6 +348,7 @@ static ssize_t regulator_max_uV_show(str

return sprintf(buf, "%d\n", rdev->constraints->max_uV);
}
+static DEVICE_ATTR(max_microvolts, 0444, regulator_max_uV_show, NULL);

static ssize_t regulator_total_uA_show(struct device *dev,
struct device_attribute *attr, char *buf)
@@ -355,6 +363,7 @@ static ssize_t regulator_total_uA_show(s
mutex_unlock(&rdev->mutex);
return sprintf(buf, "%d\n", uA);
}
+static DEVICE_ATTR(requested_microamps, 0444, regulator_total_uA_show, NULL);

static ssize_t regulator_num_users_show(struct device *dev,
struct device_attribute *attr, char *buf)
@@ -382,131 +391,106 @@ static ssize_t regulator_suspend_mem_uV_
{
struct regulator_dev *rdev = dev_get_drvdata(dev);

- if (!rdev->constraints)
- return sprintf(buf, "not defined\n");
return sprintf(buf, "%d\n", rdev->constraints->state_mem.uV);
}
+static DEVICE_ATTR(suspend_mem_microvolts, 0444,
+ regulator_suspend_mem_uV_show, NULL);

static ssize_t regulator_suspend_disk_uV_show(struct device *dev,
struct device_attribute *attr, char *buf)
{
struct regulator_dev *rdev = dev_get_drvdata(dev);

- if (!rdev->constraints)
- return sprintf(buf, "not defined\n");
return sprintf(buf, "%d\n", rdev->constraints->state_disk.uV);
}
+static DEVICE_ATTR(suspend_disk_microvolts, 0444,
+ regulator_suspend_disk_uV_show, NULL);

static ssize_t regulator_suspend_standby_uV_show(struct device *dev,
struct device_attribute *attr, char *buf)
{
struct regulator_dev *rdev = dev_get_drvdata(dev);

- if (!rdev->constraints)
- return sprintf(buf, "not defined\n");
return sprintf(buf, "%d\n", rdev->constraints->state_standby.uV);
}
+static DEVICE_ATTR(suspend_standby_microvolts, 0444,
+ regulator_suspend_standby_uV_show, NULL);

static ssize_t regulator_suspend_mem_mode_show(struct device *dev,
struct device_attribute *attr, char *buf)
{
struct regulator_dev *rdev = dev_get_drvdata(dev);

- if (!rdev->constraints)
- return sprintf(buf, "not defined\n");
return regulator_print_opmode(buf,
rdev->constraints->state_mem.mode);
}
+static DEVICE_ATTR(suspend_mem_mode, 0444,
+ regulator_suspend_mem_mode_show, NULL);

static ssize_t regulator_suspend_disk_mode_show(struct device *dev,
struct device_attribute *attr, char *buf)
{
struct regulator_dev *rdev = dev_get_drvdata(dev);

- if (!rdev->constraints)
- return sprintf(buf, "not defined\n");
return regulator_print_opmode(buf,
rdev->constraints->state_disk.mode);
}
+static DEVICE_ATTR(suspend_disk_mode, 0444,
+ regulator_suspend_disk_mode_show, NULL);

static ssize_t regulator_suspend_standby_mode_show(struct device *dev,
struct device_attribute *attr, char *buf)
{
struct regulator_dev *rdev = dev_get_drvdata(dev);

- if (!rdev->constraints)
- return sprintf(buf, "not defined\n");
return regulator_print_opmode(buf,
rdev->constraints->state_standby.mode);
}
+static DEVICE_ATTR(suspend_standby_mode, 0444,
+ regulator_suspend_standby_mode_show, NULL);

static ssize_t regulator_suspend_mem_state_show(struct device *dev,
struct device_attribute *attr, char *buf)
{
struct regulator_dev *rdev = dev_get_drvdata(dev);

- if (!rdev->constraints)
- return sprintf(buf, "not defined\n");
-
return regulator_print_state(buf,
rdev->constraints->state_mem.enabled);
}
+static DEVICE_ATTR(suspend_mem_state, 0444,
+ regulator_suspend_mem_state_show, NULL);

static ssize_t regulator_suspend_disk_state_show(struct device *dev,
struct device_attribute *attr, char *buf)
{
struct regulator_dev *rdev = dev_get_drvdata(dev);

- if (!rdev->constraints)
- return sprintf(buf, "not defined\n");
-
return regulator_print_state(buf,
rdev->constraints->state_disk.enabled);
}
+static DEVICE_ATTR(suspend_disk_state, 0444,
+ regulator_suspend_disk_state_show, NULL);

static ssize_t regulator_suspend_standby_state_show(struct device *dev,
struct device_attribute *attr, char *buf)
{
struct regulator_dev *rdev = dev_get_drvdata(dev);

- if (!rdev->constraints)
- return sprintf(buf, "not defined\n");
-
return regulator_print_state(buf,
rdev->constraints->state_standby.enabled);
}
+static DEVICE_ATTR(suspend_standby_state, 0444,
+ regulator_suspend_standby_state_show, NULL);
+

+/*
+ * These are the only attributes are present for all regulators.
+ * Other attributes are a function of regulator functionality.
+ */
static struct device_attribute regulator_dev_attrs[] = {
__ATTR(name, 0444, regulator_name_show, NULL),
- __ATTR(microvolts, 0444, regulator_uV_show, NULL),
- __ATTR(microamps, 0444, regulator_uA_show, NULL),
- __ATTR(opmode, 0444, regulator_opmode_show, NULL),
- __ATTR(state, 0444, regulator_state_show, NULL),
- __ATTR(min_microvolts, 0444, regulator_min_uV_show, NULL),
- __ATTR(min_microamps, 0444, regulator_min_uA_show, NULL),
- __ATTR(max_microvolts, 0444, regulator_max_uV_show, NULL),
- __ATTR(max_microamps, 0444, regulator_max_uA_show, NULL),
- __ATTR(requested_microamps, 0444, regulator_total_uA_show, NULL),
__ATTR(num_users, 0444, regulator_num_users_show, NULL),
__ATTR(type, 0444, regulator_type_show, NULL),
- __ATTR(suspend_mem_microvolts, 0444,
- regulator_suspend_mem_uV_show, NULL),
- __ATTR(suspend_disk_microvolts, 0444,
- regulator_suspend_disk_uV_show, NULL),
- __ATTR(suspend_standby_microvolts, 0444,
- regulator_suspend_standby_uV_show, NULL),
- __ATTR(suspend_mem_mode, 0444,
- regulator_suspend_mem_mode_show, NULL),
- __ATTR(suspend_disk_mode, 0444,
- regulator_suspend_disk_mode_show, NULL),
- __ATTR(suspend_standby_mode, 0444,
- regulator_suspend_standby_mode_show, NULL),
- __ATTR(suspend_mem_state, 0444,
- regulator_suspend_mem_state_show, NULL),
- __ATTR(suspend_disk_state, 0444,
- regulator_suspend_disk_state_show, NULL),
- __ATTR(suspend_standby_state, 0444,
- regulator_suspend_standby_state_show, NULL),
__ATTR_NULL,
};

@@ -1699,6 +1683,117 @@ int regulator_notifier_call_chain(struct
}
EXPORT_SYMBOL_GPL(regulator_notifier_call_chain);

+/*
+ * To avoid cluttering sysfs (and memory) with useless state, only
+ * create attributes that can be meaningfully displayed.
+ */
+static int add_regulator_attributes(struct regulator_dev *rdev)
+{
+ struct device *dev = &rdev->dev;
+ struct regulator_ops *ops = rdev->desc->ops;
+ int status = 0;
+
+ /* some attributes need specific methods to be displayed */
+ if (ops->get_voltage) {
+ status = device_create_file(dev, &dev_attr_microvolts);
+ if (status < 0)
+ return status;
+ }
+ if (ops->get_current_limit) {
+ status = device_create_file(dev, &dev_attr_microamps);
+ if (status < 0)
+ return status;
+ }
+ if (ops->get_mode) {
+ status = device_create_file(dev, &dev_attr_opmode);
+ if (status < 0)
+ return status;
+ }
+ if (ops->is_enabled) {
+ status = device_create_file(dev, &dev_attr_state);
+ if (status < 0)
+ return status;
+ }
+
+ /* some attributes are type-specific */
+ if (rdev->desc->type == REGULATOR_CURRENT) {
+ status = device_create_file(dev, &dev_attr_requested_microamps);
+ if (status < 0)
+ return status;
+ }
+
+ /* all the other attributes exist to support constraints;
+ * don't show them if there are no constraints, or if the
+ * relevant supporting methods are missing.
+ */
+ if (!rdev->constraints)
+ return status;
+
+ /* constraints need specific supporting methods */
+ if (ops->set_voltage) {
+ status = device_create_file(dev, &dev_attr_min_microvolts);
+ if (status < 0)
+ return status;
+ status = device_create_file(dev, &dev_attr_max_microvolts);
+ if (status < 0)
+ return status;
+ }
+ if (ops->set_current_limit) {
+ status = device_create_file(dev, &dev_attr_min_microamps);
+ if (status < 0)
+ return status;
+ status = device_create_file(dev, &dev_attr_max_microamps);
+ if (status < 0)
+ return status;
+ }
+
+ /* suspend mode constraints need multiple supporting methods */
+ if (!(ops->set_suspend_enable && ops->set_suspend_disable))
+ return status;
+
+ status = device_create_file(dev, &dev_attr_suspend_standby_state);
+ if (status < 0)
+ return status;
+ status = device_create_file(dev, &dev_attr_suspend_mem_state);
+ if (status < 0)
+ return status;
+ status = device_create_file(dev, &dev_attr_suspend_disk_state);
+ if (status < 0)
+ return status;
+
+ if (ops->set_suspend_voltage) {
+ status = device_create_file(dev,
+ &dev_attr_suspend_standby_microvolts);
+ if (status < 0)
+ return status;
+ status = device_create_file(dev,
+ &dev_attr_suspend_mem_microvolts);
+ if (status < 0)
+ return status;
+ status = device_create_file(dev,
+ &dev_attr_suspend_disk_microvolts);
+ if (status < 0)
+ return status;
+ }
+
+ if (ops->set_suspend_mode) {
+ status = device_create_file(dev,
+ &dev_attr_suspend_standby_mode);
+ if (status < 0)
+ return status;
+ status = device_create_file(dev,
+ &dev_attr_suspend_mem_mode);
+ if (status < 0)
+ return status;
+ status = device_create_file(dev,
+ &dev_attr_suspend_disk_mode);
+ if (status < 0)
+ return status;
+ }
+
+ return status;
+}
+
/**
* regulator_register - register regulator
* @regulator: regulator source
@@ -1767,6 +1862,11 @@ struct regulator_dev *regulator_register

dev_set_drvdata(&rdev->dev, rdev);

+ /* add attributes supported by this regulator */
+ ret = add_regulator_attributes(rdev);
+ if (ret < 0)
+ goto scrub;
+
/* set supply regulator if it exists */
if (init_data->supply_regulator_dev) {
ret = set_supply(rdev,
--
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