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Subject[PATCH] 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.

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

On Thu, May 13, 2010 at 11:33:04AM +0200, Daniel Mack wrote:
[...]
> > > > In short: we can't use attr groups since the attributes creation
> > > > is conditional. And we especially don't want to use the attr groups
> > > > for attrs with different modes. But it's not a problem, because...
> > >
> > > Groups have a filter callback for every member, to decide if the
> > > attribute should be created or not.
> >
> > Thanks Kay. It seems the callback was added just a few months
> > after the discussion above. ;-)
[...]
> > Daniel, I think that today we can just use the attribute group
> > mechanism, it has all needed. Do you want me to prepare a patch
> > to convert existing attributes, or do you to try it yourself?
>
> Would be good if you did that, just to see how this is interface meant
> to be used exactly. I'll adopt my patches accordingly then.

OK. It took me quite some time as my hx4700 refused to boot.
I still don't know why it doesn't boot, but I implemented
test_power driver and was able to test the draft.

Daniel, it works for me, and implementing writable properties
should be straightforward now (see is_visible callback).

Thanks,

drivers/power/power_supply.h | 7 +--
drivers/power/power_supply_core.c | 48 +++++++++++-----
drivers/power/power_supply_sysfs.c | 114 ++++++++++++------------------------
include/linux/power_supply.h | 1 +
4 files changed, 75 insertions(+), 95 deletions(-)

diff --git a/drivers/power/power_supply.h b/drivers/power/power_supply.h
index f38ba48..018de2b 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 cce75b4..91606bb 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 5b6e352..f95d934 100644
--- a/drivers/power/power_supply_sysfs.c
+++ b/drivers/power/power_supply_sysfs.c
@@ -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)
@@ -85,10 +91,13 @@ 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);

return sprintf(buf, "%d\n", value.intval);
+return 0;
}

/* Must be in the same order as POWER_SUPPLY_PROP_* */
@@ -132,67 +141,50 @@ 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,
+};
+
+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 +228,6 @@ 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;
diff --git a/include/linux/power_supply.h b/include/linux/power_supply.h
index ebd2b8f..c5f73a3 100644
--- a/include/linux/power_supply.h
+++ b/include/linux/power_supply.h
@@ -114,6 +114,7 @@ enum power_supply_property {
POWER_SUPPLY_PROP_TIME_TO_EMPTY_AVG,
POWER_SUPPLY_PROP_TIME_TO_FULL_NOW,
POWER_SUPPLY_PROP_TIME_TO_FULL_AVG,
+ POWER_SUPPLY_PROP_TYPE, /* use power_supply.type instead */
/* Properties of type `const char *' */
POWER_SUPPLY_PROP_MODEL_NAME,
POWER_SUPPLY_PROP_MANUFACTURER,
--
1.7.0.1


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