power_supply: Use attribute groups

This fixes a race between power supply device and initial
attributes creation, plus makes it possible to implement
writable properties.

[Daniel Mack - removed superflous return statement
 and dropped .mode attribute from POWER_SUPPLY_ATTR]

Suggested-by: Greg KH <gregkh@suse.de>
Suggested-by: Kay Sievers <kay.sievers@vrfy.org>
Signed-off-by: Anton Vorontsov <cbouatmailru@gmail.com>
Tested-by: Daniel Mack <daniel@caiaq.de>

3 files changed, 74 insertions, 96 deletions

diff --git a/drivers/power/power_supply.h b/drivers/power/power_supply.h
index f38ba482be75..018de2b26998 100644
--- a/drivers/power/power_supply.h
+++ b/drivers/power/power_supply.h
@@ -12,15 +12,12 @@
 
 #ifdef CONFIG_SYSFS
 
-extern int power_supply_create_attrs(struct power_supply *psy);
-extern void power_supply_remove_attrs(struct power_supply *psy);
+extern void power_supply_init_attrs(struct device_type *dev_type);
 extern int power_supply_uevent(struct device *dev, struct kobj_uevent_env *env);
 
 #else
 
-static inline int power_supply_create_attrs(struct power_supply *psy)
-{ return 0; }
-static inline void power_supply_remove_attrs(struct power_supply *psy) {}
+static inline void power_supply_init_attrs(struct device_type *dev_type) {}
 #define power_supply_uevent NULL
 
 #endif /* CONFIG_SYSFS */
diff --git a/drivers/power/power_supply_core.c b/drivers/power/power_supply_core.c
index cce75b40b435..91606bb55318 100644
--- a/drivers/power/power_supply_core.c
+++ b/drivers/power/power_supply_core.c
@@ -13,6 +13,7 @@
 #include <linux/module.h>
 #include <linux/types.h>
 #include <linux/init.h>
+#include <linux/slab.h>
 #include <linux/device.h>
 #include <linux/err.h>
 #include <linux/power_supply.h>
@@ -22,6 +23,8 @@
 struct class *power_supply_class;
 EXPORT_SYMBOL_GPL(power_supply_class);
 
+static struct device_type power_supply_dev_type;
+
 static int __power_supply_changed_work(struct device *dev, void *data)
 {
         struct power_supply *psy = (struct power_supply *)data;
@@ -144,22 +147,39 @@ struct power_supply *power_supply_get_by_name(char *name)
 }
 EXPORT_SYMBOL_GPL(power_supply_get_by_name);
 
+static void power_supply_dev_release(struct device *dev)
+{
+        pr_debug("device: '%s': %s\n", dev_name(dev), __func__);
+        kfree(dev);
+}
+
 int power_supply_register(struct device *parent, struct power_supply *psy)
 {
-        int rc = 0;
+        struct device *dev;
+        int rc;
 
-        psy->dev = device_create(power_supply_class, parent, 0, psy,
-                                 "%s", psy->name);
-        if (IS_ERR(psy->dev)) {
-                rc = PTR_ERR(psy->dev);
-                goto dev_create_failed;
-        }
+        dev = kzalloc(sizeof(*dev), GFP_KERNEL);
+        if (!dev)
+                return -ENOMEM;
 
-        INIT_WORK(&psy->changed_work, power_supply_changed_work);
+        device_initialize(dev);
 
-        rc = power_supply_create_attrs(psy);
+        dev->class = power_supply_class;
+        dev->type = &power_supply_dev_type;
+        dev->parent = parent;
+        dev->release = power_supply_dev_release;
+        dev_set_drvdata(dev, psy);
+        psy->dev = dev;
+
+        rc = kobject_set_name(&dev->kobj, "%s", psy->name);
+        if (rc)
+                goto kobject_set_name_failed;
+
+        rc = device_add(dev);
         if (rc)
-                goto create_attrs_failed;
+                goto device_add_failed;
+
+        INIT_WORK(&psy->changed_work, power_supply_changed_work);
 
         rc = power_supply_create_triggers(psy);
         if (rc)
@@ -170,10 +190,10 @@ int power_supply_register(struct device *parent, struct power_supply *psy)
         goto success;
 
 create_triggers_failed:
-        power_supply_remove_attrs(psy);
-create_attrs_failed:
         device_unregister(psy->dev);
-dev_create_failed:
+kobject_set_name_failed:
+device_add_failed:
+        kfree(dev);
 success:
         return rc;
 }
@@ -183,7 +203,6 @@ void power_supply_unregister(struct power_supply *psy)
 {
         flush_scheduled_work();
         power_supply_remove_triggers(psy);
-        power_supply_remove_attrs(psy);
         device_unregister(psy->dev);
 }
 EXPORT_SYMBOL_GPL(power_supply_unregister);
@@ -196,6 +215,7 @@ static int __init power_supply_class_init(void)
                 return PTR_ERR(power_supply_class);
 
         power_supply_class->dev_uevent = power_supply_uevent;
+        power_supply_init_attrs(&power_supply_dev_type);
 
         return 0;
 }
diff --git a/drivers/power/power_supply_sysfs.c b/drivers/power/power_supply_sysfs.c
index 5b6e352ac7c1..7d7593cad7d9 100644
--- a/drivers/power/power_supply_sysfs.c
+++ b/drivers/power/power_supply_sysfs.c
@@ -31,7 +31,7 @@
 
 #define POWER_SUPPLY_ATTR(_name)                                        \
 {                                                                       \
-        .attr = { .name = #_name, .mode = 0444 },       \
+        .attr = { .name = #_name },                                     \
         .show = power_supply_show_property,                             \
         .store = NULL,                                                  \
 }
@@ -41,6 +41,9 @@ static struct device_attribute power_supply_attrs[];
 static ssize_t power_supply_show_property(struct device *dev,
                                           struct device_attribute *attr,
                                           char *buf) {
+        static char *type_text[] = {
+                "Battery", "UPS", "Mains", "USB"
+        };
         static char *status_text[] = {
                 "Unknown", "Charging", "Discharging", "Not charging", "Full"
         };
@@ -58,12 +61,15 @@ static ssize_t power_supply_show_property(struct device *dev,
         static char *capacity_level_text[] = {
                 "Unknown", "Critical", "Low", "Normal", "High", "Full"
         };
-        ssize_t ret;
+        ssize_t ret = 0;
         struct power_supply *psy = dev_get_drvdata(dev);
         const ptrdiff_t off = attr - power_supply_attrs;
         union power_supply_propval value;
 
-        ret = psy->get_property(psy, off, &value);
+        if (off == POWER_SUPPLY_PROP_TYPE)
+                value.intval = psy->type;
+        else
+                ret = psy->get_property(psy, off, &value);
 
         if (ret < 0) {
                 if (ret == -ENODATA)
@@ -85,6 +91,8 @@ static ssize_t power_supply_show_property(struct device *dev,
                 return sprintf(buf, "%s\n", technology_text[value.intval]);
         else if (off == POWER_SUPPLY_PROP_CAPACITY_LEVEL)
                 return sprintf(buf, "%s\n", capacity_level_text[value.intval]);
+        else if (off == POWER_SUPPLY_PROP_TYPE)
+                return sprintf(buf, "%s\n", type_text[value.intval]);
         else if (off >= POWER_SUPPLY_PROP_MODEL_NAME)
                 return sprintf(buf, "%s\n", value.strval);
 
@@ -132,67 +140,50 @@ static struct device_attribute power_supply_attrs[] = {
         POWER_SUPPLY_ATTR(time_to_empty_avg),
         POWER_SUPPLY_ATTR(time_to_full_now),
         POWER_SUPPLY_ATTR(time_to_full_avg),
+        POWER_SUPPLY_ATTR(type),
         /* Properties of type `const char *' */
         POWER_SUPPLY_ATTR(model_name),
         POWER_SUPPLY_ATTR(manufacturer),
         POWER_SUPPLY_ATTR(serial_number),
 };
 
-static ssize_t power_supply_show_static_attrs(struct device *dev,
-                                              struct device_attribute *attr,
-                                              char *buf) {
-        static char *type_text[] = { "Battery", "UPS", "Mains", "USB" };
-        struct power_supply *psy = dev_get_drvdata(dev);
-
-        return sprintf(buf, "%s\n", type_text[psy->type]);
-}
-
-static struct device_attribute power_supply_static_attrs[] = {
-        __ATTR(type, 0444, power_supply_show_static_attrs, NULL),
-};
+static struct attribute *
+__power_supply_attrs[ARRAY_SIZE(power_supply_attrs) + 1];
 
-int power_supply_create_attrs(struct power_supply *psy)
+static mode_t power_supply_attr_is_visible(struct kobject *kobj,
+                                           struct attribute *attr,
+                                           int attrno)
 {
-        int rc = 0;
-        int i, j;
-
-        for (i = 0; i < ARRAY_SIZE(power_supply_static_attrs); i++) {
-                rc = device_create_file(psy->dev,
-                            &power_supply_static_attrs[i]);
-                if (rc)
-                        goto statics_failed;
-        }
+        struct device *dev = container_of(kobj, struct device, kobj);
+        struct power_supply *psy = dev_get_drvdata(dev);
+        int i;
 
-        for (j = 0; j < psy->num_properties; j++) {
-                rc = device_create_file(psy->dev,
-                            &power_supply_attrs[psy->properties[j]]);
-                if (rc)
-                        goto dynamics_failed;
+        for (i = 0; i < psy->num_properties; i++) {
+                if (psy->properties[i] == attrno)
+                        return 0444;
         }
 
-        goto succeed;
-
-dynamics_failed:
-        while (j--)
-                device_remove_file(psy->dev,
-                           &power_supply_attrs[psy->properties[j]]);
-statics_failed:
-        while (i--)
-                device_remove_file(psy->dev, &power_supply_static_attrs[i]);
-succeed:
-        return rc;
+        return 0;
 }
 
-void power_supply_remove_attrs(struct power_supply *psy)
+static struct attribute_group power_supply_attr_group = {
+        .attrs = __power_supply_attrs,
+        .is_visible = power_supply_attr_is_visible,
+};
+
+static const struct attribute_group *power_supply_attr_groups[] = {
+        &power_supply_attr_group,
+        NULL,
+};
+
+void power_supply_init_attrs(struct device_type *dev_type)
 {
         int i;
 
-        for (i = 0; i < ARRAY_SIZE(power_supply_static_attrs); i++)
-                device_remove_file(psy->dev, &power_supply_static_attrs[i]);
+        dev_type->groups = power_supply_attr_groups;
 
-        for (i = 0; i < psy->num_properties; i++)
-                device_remove_file(psy->dev,
-                            &power_supply_attrs[psy->properties[i]]);
+        for (i = 0; i < ARRAY_SIZE(power_supply_attrs); i++)
+                __power_supply_attrs[i] = &power_supply_attrs[i].attr;
 }
 
 static char *kstruprdup(const char *str, gfp_t gfp)
@@ -236,36 +227,6 @@ int power_supply_uevent(struct device *dev, struct kobj_uevent_env *env)
         if (!prop_buf)
                 return -ENOMEM;
 
-        for (j = 0; j < ARRAY_SIZE(power_supply_static_attrs); j++) {
-                struct device_attribute *attr;
-                char *line;
-
-                attr = &power_supply_static_attrs[j];
-
-                ret = power_supply_show_static_attrs(dev, attr, prop_buf);
-                if (ret < 0)
-                        goto out;
-
-                line = strchr(prop_buf, '\n');
-                if (line)
-                        *line = 0;
-
-                attrname = kstruprdup(attr->attr.name, GFP_KERNEL);
-                if (!attrname) {
-                        ret = -ENOMEM;
-                        goto out;
-                }
-
-                dev_dbg(dev, "Static prop %s=%s\n", attrname, prop_buf);
-
-                ret = add_uevent_var(env, "POWER_SUPPLY_%s=%s", attrname, prop_buf);
-                kfree(attrname);
-                if (ret)
-                        goto out;
-        }
-
-        dev_dbg(dev, "%zd dynamic props\n", psy->num_properties);
-
         for (j = 0; j < psy->num_properties; j++) {
                 struct device_attribute *attr;
                 char *line;