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, 148 insertions, 48 deletions

diff --git a/drivers/regulator/core.c b/drivers/regulator/core.c
index 5109f7d4809a..9a5ff97d158d 100644
--- a/drivers/regulator/core.c
+++ b/drivers/regulator/core.c
@@ -242,6 +242,7 @@ static ssize_t regulator_uV_show(struct device *dev,
 
         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)
@@ -250,6 +251,7 @@ static ssize_t regulator_uA_show(struct device *dev,
 
         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)
@@ -289,6 +291,7 @@ static ssize_t regulator_opmode_show(struct device *dev,
 
         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)
 {
@@ -307,6 +310,7 @@ static ssize_t regulator_state_show(struct device *dev,
 
         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)
@@ -318,6 +322,7 @@ static ssize_t regulator_min_uA_show(struct device *dev,
 
         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)
@@ -329,6 +334,7 @@ static ssize_t regulator_max_uA_show(struct device *dev,
 
         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)
@@ -340,6 +346,7 @@ static ssize_t regulator_min_uV_show(struct device *dev,
 
         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)
@@ -351,6 +358,7 @@ static ssize_t regulator_max_uV_show(struct device *dev,
 
         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)
@@ -365,6 +373,7 @@ static ssize_t regulator_total_uA_show(struct device *dev,
         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)
@@ -392,131 +401,106 @@ static ssize_t regulator_suspend_mem_uV_show(struct device *dev,
 {
         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,
 };
 
@@ -1711,6 +1695,117 @@ int regulator_notifier_call_chain(struct regulator_dev *rdev,
 }
 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
@@ -1779,6 +1874,11 @@ struct regulator_dev *regulator_register(struct regulator_desc *regulator_desc,
 
         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,