Date:	Fri, 30 Jan 2015 20:29:31 +0100
From:	Takashi Iwai <tiwai@...e.de>
To:	Mark Brown <broonie@...nel.org>
Cc:	Liam Girdwood <lgirdwood@...il.com>, linux-kernel@...r.kernel.org
Subject: [PATCH] regulator: Build sysfs entries with static attribute groups

Instead of calling device_create_file() manually after the device
registration, put all in attribute groups and filter the unwanted ones
via is_visible callback.  This not only simplifies the code but also
avoids the possible race between the device registration and sysfs
registration.

Signed-off-by: Takashi Iwai <tiwai@...e.de>
---
 drivers/regulator/core.c | 235 ++++++++++++++++++++++-------------------------
 1 file changed, 108 insertions(+), 127 deletions(-)

diff --git a/drivers/regulator/core.c b/drivers/regulator/core.c
index e225711bb8bc..4c8feae615f5 100644
--- a/drivers/regulator/core.c
+++ b/drivers/regulator/core.c
@@ -632,30 +632,6 @@ static ssize_t regulator_bypass_show(struct device *dev,
 static DEVICE_ATTR(bypass, 0444,
 		   regulator_bypass_show, NULL);
 
-/*
- * These are the only attributes are present for all regulators.
- * Other attributes are a function of regulator functionality.
- */
-static struct attribute *regulator_dev_attrs[] = {
-	&dev_attr_name.attr,
-	&dev_attr_num_users.attr,
-	&dev_attr_type.attr,
-	NULL,
-};
-ATTRIBUTE_GROUPS(regulator_dev);
-
-static void regulator_dev_release(struct device *dev)
-{
-	struct regulator_dev *rdev = dev_get_drvdata(dev);
-	kfree(rdev);
-}
-
-static struct class regulator_class = {
-	.name = "regulator",
-	.dev_release = regulator_dev_release,
-	.dev_groups = regulator_dev_groups,
-};
-
 /* Calculate the new optimum regulator operating mode based on the new total
  * consumer load. All locks held by caller */
 static void drms_uA_update(struct regulator_dev *rdev)
@@ -3434,126 +3410,136 @@ int regulator_mode_to_status(unsigned int mode)
 }
 EXPORT_SYMBOL_GPL(regulator_mode_to_status);
 
+static struct attribute *regulator_dev_attrs[] = {
+	&dev_attr_name.attr,
+	&dev_attr_num_users.attr,
+	&dev_attr_type.attr,
+	&dev_attr_microvolts.attr,
+	&dev_attr_microamps.attr,
+	&dev_attr_opmode.attr,
+	&dev_attr_state.attr,
+	&dev_attr_status.attr,
+	&dev_attr_bypass.attr,
+	&dev_attr_requested_microamps.attr,
+	&dev_attr_min_microvolts.attr,
+	&dev_attr_max_microvolts.attr,
+	&dev_attr_min_microamps.attr,
+	&dev_attr_max_microamps.attr,
+	&dev_attr_suspend_standby_state.attr,
+	&dev_attr_suspend_mem_state.attr,
+	&dev_attr_suspend_disk_state.attr,
+	&dev_attr_suspend_standby_microvolts.attr,
+	&dev_attr_suspend_mem_microvolts.attr,
+	&dev_attr_suspend_disk_microvolts.attr,
+	&dev_attr_suspend_standby_mode.attr,
+	&dev_attr_suspend_mem_mode.attr,
+	&dev_attr_suspend_disk_mode.attr,
+	NULL
+};
+
 /*
  * 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)
+static umode_t regulator_attr_is_visible(struct kobject *kobj,
+					 struct attribute *attr, int idx)
 {
-	struct device *dev = &rdev->dev;
+	struct device *dev = kobj_to_dev(kobj);
+	struct regulator_dev *rdev = container_of(dev, struct regulator_dev, dev);
 	const struct regulator_ops *ops = rdev->desc->ops;
-	int status = 0;
+	umode_t mode = attr->mode;
+
+	/* these three are always present */
+	if (attr == &dev_attr_name.attr ||
+	    attr == &dev_attr_num_users.attr ||
+	    attr == &dev_attr_type.attr)
+		return mode;
 
 	/* some attributes need specific methods to be displayed */
-	if ((ops->get_voltage && ops->get_voltage(rdev) >= 0) ||
-	    (ops->get_voltage_sel && ops->get_voltage_sel(rdev) >= 0) ||
-	    (ops->list_voltage && ops->list_voltage(rdev, 0) >= 0) ||
-		(rdev->desc->fixed_uV && (rdev->desc->n_voltages == 1))) {
-		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 (rdev->ena_pin || ops->is_enabled) {
-		status = device_create_file(dev, &dev_attr_state);
-		if (status < 0)
-			return status;
-	}
-	if (ops->get_status) {
-		status = device_create_file(dev, &dev_attr_status);
-		if (status < 0)
-			return status;
-	}
-	if (ops->get_bypass) {
-		status = device_create_file(dev, &dev_attr_bypass);
-		if (status < 0)
-			return status;
+	if (attr == &dev_attr_microvolts.attr) {
+		if ((ops->get_voltage && ops->get_voltage(rdev) >= 0) ||
+		    (ops->get_voltage_sel && ops->get_voltage_sel(rdev) >= 0) ||
+		    (ops->list_voltage && ops->list_voltage(rdev, 0) >= 0) ||
+		    (rdev->desc->fixed_uV && rdev->desc->n_voltages == 1))
+			return mode;
+		return 0;
 	}
 
+	if (attr == &dev_attr_microamps.attr)
+		return ops->get_current_limit ? mode : 0;
+
+	if (attr == &dev_attr_opmode.attr)
+		return ops->get_mode ? mode : 0;
+
+	if (attr == &dev_attr_state.attr)
+		return (rdev->ena_pin || ops->is_enabled) ? mode : 0;
+
+	if (attr == &dev_attr_status.attr)
+		return ops->get_status ? mode : 0;
+
+	if (attr == &dev_attr_bypass.attr)
+		return ops->get_bypass ? mode : 0;
+
 	/* 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;
-	}
+	if (attr == &dev_attr_requested_microamps.attr)
+		return rdev->desc->type == REGULATOR_CURRENT ? mode : 0;
 
 	/* 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;
+		return 0;
 
 	/* constraints need specific supporting methods */
-	if (ops->set_voltage || ops->set_voltage_sel) {
-		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;
-	}
-
-	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 (attr == &dev_attr_min_microvolts.attr ||
+	    attr == &dev_attr_max_microvolts.attr)
+		return (ops->set_voltage || ops->set_voltage_sel) ? mode : 0;
+
+	if (attr == &dev_attr_min_microamps.attr ||
+	    attr == &dev_attr_max_microamps.attr)
+		return ops->set_current_limit ? mode : 0;
+
+	if (attr == &dev_attr_suspend_standby_state.attr ||
+	    attr == &dev_attr_suspend_mem_state.attr ||
+	    attr == &dev_attr_suspend_disk_state.attr)
+		return mode;
+
+	if (attr == &dev_attr_suspend_standby_microvolts.attr ||
+	    attr == &dev_attr_suspend_mem_microvolts.attr ||
+	    attr == &dev_attr_suspend_disk_microvolts.attr)
+		return ops->set_suspend_voltage ? mode : 0;
+
+	if (attr == &dev_attr_suspend_standby_mode.attr ||
+	    attr == &dev_attr_suspend_mem_mode.attr ||
+	    attr == &dev_attr_suspend_disk_mode.attr)
+		return ops->set_suspend_mode ? mode : 0;
+
+	return mode;
+}
+
+static const struct attribute_group regulator_dev_group = {
+	.attrs = regulator_dev_attrs,
+	.is_visible = regulator_attr_is_visible,
+};
+
+static const struct attribute_group *regulator_dev_groups[] = {
+	&regulator_dev_group,
+	NULL
+};
 
-	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;
+static void regulator_dev_release(struct device *dev)
+{
+	struct regulator_dev *rdev = dev_get_drvdata(dev);
+	kfree(rdev);
 }
 
+static struct class regulator_class = {
+	.name = "regulator",
+	.dev_release = regulator_dev_release,
+	.dev_groups = regulator_dev_groups,
+};
+
 static void rdev_init_debugfs(struct regulator_dev *rdev)
 {
 	rdev->debugfs = debugfs_create_dir(rdev_get_name(rdev), debugfs_root);
@@ -3692,11 +3678,6 @@ regulator_register(const struct regulator_desc *regulator_desc,
 	if (ret < 0)
 		goto scrub;
 
-	/* add attributes supported by this regulator */
-	ret = add_regulator_attributes(rdev);
-	if (ret < 0)
-		goto scrub;
-
 	if (init_data && init_data->supply_regulator)
 		supply = init_data->supply_regulator;
 	else if (regulator_desc->supply_name)
-- 
2.2.2

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