Commit 4a11b59d authored by Anton Vorontsov's avatar Anton Vorontsov Committed by David Woodhouse

[BATTERY] Universal power supply class (was: battery class)

This class is result of "external power" and "battery" classes merge,
as suggested by David Woodhouse. He also implemented uevent support.

Here how userspace seeing it now:

    	# ls /sys/class/power\ supply/
    	ac  main-battery  usb

    	# cat /sys/class/power\ supply/ac/type
    	AC

    	# cat /sys/class/power\ supply/usb/type
    	USB

    	# cat /sys/class/power\ supply/main-battery/type
    	Battery

    	# cat /sys/class/power\ supply/ac/online
    	1

    	# cat /sys/class/power\ supply/usb/online
    	0

    	# cat /sys/class/power\ supply/main-battery/status
    	Charging

    	# cat /sys/class/leds/h5400\:red-left/trigger
    	none h5400-radio timer hwtimer ac-online usb-online
    	main-battery-charging-or-full [main-battery-charging]
    	main-battery-full
Signed-off-by: default avatarAnton Vorontsov <cbou@mail.ru>
Signed-off-by: default avatarDavid Woodhouse <dwmw2@infradead.org>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
parent 7dcca30a
Linux power supply class
========================
Synopsis
~~~~~~~~
Power supply class used to represent battery, UPS, AC or DC power supply
properties to user-space.
It defines core set of attributes, which should be applicable to (almost)
every power supply out there. Attributes are available via sysfs and uevent
interfaces.
Each attribute has well defined meaning, up to unit of measure used. While
the attributes provided are believed to be universally applicable to any
power supply, specific monitoring hardware may not be able to provide them
all, so any of them may be skipped.
Power supply class is extensible, and allows to define drivers own attributes.
The core attribute set is subject to the standard Linux evolution (i.e.
if it will be found that some attribute is applicable to many power supply
types or their drivers, it can be added to the core set).
It also integrates with LED framework, for the purpose of providing
typically expected feedback of battery charging/fully charged status and
AC/USB power supply online status. (Note that specific details of the
indication (including whether to use it at all) are fully controllable by
user and/or specific machine defaults, per design principles of LED
framework).
Attributes/properties
~~~~~~~~~~~~~~~~~~~~~
Power supply class has predefined set of attributes, this eliminates code
duplication across drivers. Power supply class insist on reusing its
predefined attributes *and* their units.
So, userspace gets predictable set of attributes and their units for any
kind of power supply, and can process/present them to a user in consistent
manner. Results for different power supplies and machines are also directly
comparable.
See drivers/power/ds2760_battery.c and drivers/power/pda_power.c for the
example how to declare and handle attributes.
Units
~~~~~
Quoting include/linux/power_supply.h:
All voltages, currents, charges, energies, time and temperatures in µV,
µA, µAh, µWh, seconds and tenths of degree Celsius unless otherwise
stated. It's driver's job to convert its raw values to units in which
this class operates.
Attributes/properties detailed
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
~ ~ ~ ~ ~ ~ ~ Charge/Energy/Capacity - how to not confuse ~ ~ ~ ~ ~ ~ ~
~ ~
~ Because both "charge" (µAh) and "energy" (µWh) represents "capacity" ~
~ of battery, this class distinguish these terms. Don't mix them! ~
~ ~
~ CHARGE_* attributes represents capacity in µAh only. ~
~ ENERGY_* attributes represents capacity in µWh only. ~
~ CAPACITY attribute represents capacity in *percents*, from 0 to 100. ~
~ ~
~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~
Postfixes:
_AVG - *hardware* averaged value, use it if your hardware is really able to
report averaged values.
_NOW - momentary/instantaneous values.
STATUS - this attribute represents operating status (charging, full,
discharging (i.e. powering a load), etc.). This corresponds to
BATTERY_STATUS_* values, as defined in battery.h.
HEALTH - represents health of the battery, values corresponds to
POWER_SUPPLY_HEALTH_*, defined in battery.h.
VOLTAGE_MAX_DESIGN, VOLTAGE_MIN_DESIGN - design values for maximal and
minimal power supply voltages. Maximal/minimal means values of voltages
when battery considered "full"/"empty" at normal conditions. Yes, there is
no direct relation between voltage and battery capacity, but some dumb
batteries use voltage for very approximated calculation of capacity.
Battery driver also can use this attribute just to inform userspace
about maximal and minimal voltage thresholds of a given battery.
CHARGE_FULL_DESIGN, CHARGE_EMPTY_DESIGN - design charge values, when
battery considered full/empty.
ENERGY_FULL_DESIGN, ENERGY_EMPTY_DESIGN - same as above but for energy.
CHARGE_FULL, CHARGE_EMPTY - These attributes means "last remembered value
of charge when battery became full/empty". It also could mean "value of
charge when battery considered full/empty at given conditions (temperature,
age)". I.e. these attributes represents real thresholds, not design values.
ENERGY_FULL, ENERGY_EMPTY - same as above but for energy.
CAPACITY - capacity in percents.
CAPACITY_LEVEL - capacity level. This corresponds to
POWER_SUPPLY_CAPACITY_LEVEL_*.
TEMP - temperature of the power supply.
TEMP_AMBIENT - ambient temperature.
TIME_TO_EMPTY - seconds left for battery to be considered empty (i.e.
while battery powers a load)
TIME_TO_FULL - seconds left for battery to be considered full (i.e.
while battery is charging)
Battery <-> external power supply interaction
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Often power supplies are acting as supplies and supplicants at the same
time. Batteries are good example. So, batteries usually care if they're
externally powered or not.
For that case, power supply class implements notification mechanism for
batteries.
External power supply (AC) lists supplicants (batteries) names in
"supplied_to" struct member, and each power_supply_changed() call
issued by external power supply will notify supplicants via
external_power_changed callback.
QA
~~
Q: Where is POWER_SUPPLY_PROP_XYZ attribute?
A: If you cannot find attribute suitable for your driver needs, feel free
to add it and send patch along with your driver.
The attributes available currently are the ones currently provided by the
drivers written.
Good candidates to add in future: model/part#, cycle_time, manufacturer,
etc.
Q: I have some very specific attribute (e.g. battery color), should I add
this attribute to standard ones?
A: Most likely, no. Such attribute can be placed in the driver itself, if
it is useful. Of course, if the attribute in question applicable to
large set of batteries, provided by many drivers, and/or comes from
some general battery specification/standard, it may be a candidate to
be added to the core attribute set.
Q: Suppose, my battery monitoring chip/firmware does not provides capacity
in percents, but provides charge_{now,full,empty}. Should I calculate
percentage capacity manually, inside the driver, and register CAPACITY
attribute? The same question about time_to_empty/time_to_full.
A: Most likely, no. This class is designed to export properties which are
directly measurable by the specific hardware available.
Inferring not available properties using some heuristics or mathematical
model is not subject of work for a battery driver. Such functionality
should be factored out, and in fact, apm_power, the driver to serve
legacy APM API on top of power supply class, uses a simple heuristic of
approximating remaining battery capacity based on its charge, current,
voltage and so on. But full-fledged battery model is likely not subject
for kernel at all, as it would require floating point calculation to deal
with things like differential equations and Kalman filters. This is
better be handled by batteryd/libbattery, yet to be written.
......@@ -54,6 +54,8 @@ source "drivers/spi/Kconfig"
source "drivers/w1/Kconfig"
source "drivers/power/Kconfig"
source "drivers/hwmon/Kconfig"
source "drivers/mfd/Kconfig"
......
......@@ -61,6 +61,7 @@ obj-$(CONFIG_I2O) += message/
obj-$(CONFIG_RTC_LIB) += rtc/
obj-y += i2c/
obj-$(CONFIG_W1) += w1/
obj-$(CONFIG_POWER_SUPPLY) += power/
obj-$(CONFIG_HWMON) += hwmon/
obj-$(CONFIG_PHONE) += telephony/
obj-$(CONFIG_MD) += md/
......
menuconfig POWER_SUPPLY
tristate "Power supply class support"
help
Say Y here to enable power supply class support. This allows
power supply (batteries, AC, USB) monitoring by userspace
via sysfs and uevent (if available) and/or APM kernel interface
(if selected below).
if POWER_SUPPLY
config POWER_SUPPLY_DEBUG
bool "Power supply debug"
help
Say Y here to enable debugging messages for power supply class
and drivers.
endif # POWER_SUPPLY
power_supply-objs := power_supply_core.o
ifeq ($(CONFIG_SYSFS),y)
power_supply-objs += power_supply_sysfs.o
endif
ifeq ($(CONFIG_LEDS_TRIGGERS),y)
power_supply-objs += power_supply_leds.o
endif
ifeq ($(CONFIG_POWER_SUPPLY_DEBUG),y)
EXTRA_CFLAGS += -DDEBUG
endif
obj-$(CONFIG_POWER_SUPPLY) += power_supply.o
/*
* Functions private to power supply class
*
* Copyright © 2007 Anton Vorontsov <cbou@mail.ru>
* Copyright © 2004 Szabolcs Gyurko
* Copyright © 2003 Ian Molton <spyro@f2s.com>
*
* Modified: 2004, Oct Szabolcs Gyurko
*
* You may use this code as per GPL version 2
*/
#ifdef CONFIG_SYSFS
extern int power_supply_create_attrs(struct power_supply *psy);
extern void power_supply_remove_attrs(struct power_supply *psy);
extern int power_supply_uevent(struct device *dev, char **envp, int num_envp,
char *buffer, int buffer_size);
#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) {}
#define power_supply_uevent NULL
#endif /* CONFIG_SYSFS */
#ifdef CONFIG_LEDS_TRIGGERS
extern void power_supply_update_leds(struct power_supply *psy);
extern int power_supply_create_triggers(struct power_supply *psy);
extern void power_supply_remove_triggers(struct power_supply *psy);
#else
static inline void power_supply_update_leds(struct power_supply *psy) {}
static inline int power_supply_create_triggers(struct power_supply *psy)
{ return 0; }
static inline void power_supply_remove_triggers(struct power_supply *psy) {}
#endif /* CONFIG_LEDS_TRIGGERS */
/*
* Universal power supply monitor class
*
* Copyright © 2007 Anton Vorontsov <cbou@mail.ru>
* Copyright © 2004 Szabolcs Gyurko
* Copyright © 2003 Ian Molton <spyro@f2s.com>
*
* Modified: 2004, Oct Szabolcs Gyurko
*
* You may use this code as per GPL version 2
*/
#include <linux/module.h>
#include <linux/types.h>
#include <linux/init.h>
#include <linux/device.h>
#include <linux/err.h>
#include <linux/power_supply.h>
#include "power_supply.h"
struct class *power_supply_class;
static void power_supply_changed_work(struct work_struct *work)
{
struct power_supply *psy = container_of(work, struct power_supply,
changed_work);
int i;
dev_dbg(psy->dev, "%s\n", __FUNCTION__);
for (i = 0; i < psy->num_supplicants; i++) {
struct device *dev;
down(&power_supply_class->sem);
list_for_each_entry(dev, &power_supply_class->devices, node) {
struct power_supply *pst = dev_get_drvdata(dev);
if (!strcmp(psy->supplied_to[i], pst->name)) {
if (pst->external_power_changed)
pst->external_power_changed(pst);
}
}
up(&power_supply_class->sem);
}
power_supply_update_leds(psy);
kobject_uevent(&psy->dev->kobj, KOBJ_CHANGE);
return;
}
void power_supply_changed(struct power_supply *psy)
{
dev_dbg(psy->dev, "%s\n", __FUNCTION__);
schedule_work(&psy->changed_work);
return;
}
int power_supply_am_i_supplied(struct power_supply *psy)
{
union power_supply_propval ret = {0,};
struct device *dev;
down(&power_supply_class->sem);
list_for_each_entry(dev, &power_supply_class->devices, node) {
struct power_supply *epsy = dev_get_drvdata(dev);
int i;
for (i = 0; i < epsy->num_supplicants; i++) {
if (!strcmp(epsy->supplied_to[i], psy->name)) {
if (epsy->get_property(epsy,
POWER_SUPPLY_PROP_ONLINE, &ret))
continue;
if (ret.intval)
goto out;
}
}
}
out:
up(&power_supply_class->sem);
dev_dbg(psy->dev, "%s %d\n", __FUNCTION__, ret.intval);
return ret.intval;
}
int power_supply_register(struct device *parent, struct power_supply *psy)
{
int rc = 0;
psy->dev = device_create(power_supply_class, parent, 0,
"%s", psy->name);
if (IS_ERR(psy->dev)) {
rc = PTR_ERR(psy->dev);
goto dev_create_failed;
}
dev_set_drvdata(psy->dev, psy);
INIT_WORK(&psy->changed_work, power_supply_changed_work);
rc = power_supply_create_attrs(psy);
if (rc)
goto create_attrs_failed;
rc = power_supply_create_triggers(psy);
if (rc)
goto create_triggers_failed;
power_supply_changed(psy);
goto success;
create_triggers_failed:
power_supply_remove_attrs(psy);
create_attrs_failed:
device_unregister(psy->dev);
dev_create_failed:
success:
return rc;
}
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);
return;
}
static int __init power_supply_class_init(void)
{
power_supply_class = class_create(THIS_MODULE, "power_supply");
if (IS_ERR(power_supply_class))
return PTR_ERR(power_supply_class);
power_supply_class->dev_uevent = power_supply_uevent;
return 0;
}
static void __exit power_supply_class_exit(void)
{
class_destroy(power_supply_class);
return;
}
EXPORT_SYMBOL_GPL(power_supply_changed);
EXPORT_SYMBOL_GPL(power_supply_am_i_supplied);
EXPORT_SYMBOL_GPL(power_supply_register);
EXPORT_SYMBOL_GPL(power_supply_unregister);
/* exported for the APM Power driver, APM emulation */
EXPORT_SYMBOL_GPL(power_supply_class);
subsys_initcall(power_supply_class_init);
module_exit(power_supply_class_exit);
MODULE_DESCRIPTION("Universal power supply monitor class");
MODULE_AUTHOR("Ian Molton <spyro@f2s.com>, "
"Szabolcs Gyurko, "
"Anton Vorontsov <cbou@mail.ru>");
MODULE_LICENSE("GPL");
/*
* LEDs triggers for power supply class
*
* Copyright © 2007 Anton Vorontsov <cbou@mail.ru>
* Copyright © 2004 Szabolcs Gyurko
* Copyright © 2003 Ian Molton <spyro@f2s.com>
*
* Modified: 2004, Oct Szabolcs Gyurko
*
* You may use this code as per GPL version 2
*/
#include <linux/power_supply.h>
/* Battery specific LEDs triggers. */
static void power_supply_update_bat_leds(struct power_supply *psy)
{
union power_supply_propval status;
if (psy->get_property(psy, POWER_SUPPLY_PROP_STATUS, &status))
return;
dev_dbg(psy->dev, "%s %d\n", __FUNCTION__, status.intval);
switch (status.intval) {
case POWER_SUPPLY_STATUS_FULL:
led_trigger_event(psy->charging_full_trig, LED_FULL);
led_trigger_event(psy->charging_trig, LED_OFF);
led_trigger_event(psy->full_trig, LED_FULL);
break;
case POWER_SUPPLY_STATUS_CHARGING:
led_trigger_event(psy->charging_full_trig, LED_FULL);
led_trigger_event(psy->charging_trig, LED_FULL);
led_trigger_event(psy->full_trig, LED_OFF);
break;
default:
led_trigger_event(psy->charging_full_trig, LED_OFF);
led_trigger_event(psy->charging_trig, LED_OFF);
led_trigger_event(psy->full_trig, LED_OFF);
break;
}
return;
}
static int power_supply_create_bat_triggers(struct power_supply *psy)
{
int rc = 0;
psy->charging_full_trig_name = kmalloc(strlen(psy->name) +
sizeof("-charging-or-full"), GFP_KERNEL);
if (!psy->charging_full_trig_name)
goto charging_full_failed;
psy->charging_trig_name = kmalloc(strlen(psy->name) +
sizeof("-charging"), GFP_KERNEL);
if (!psy->charging_trig_name)
goto charging_failed;
psy->full_trig_name = kmalloc(strlen(psy->name) +
sizeof("-full"), GFP_KERNEL);
if (!psy->full_trig_name)
goto full_failed;
strcpy(psy->charging_full_trig_name, psy->name);
strcat(psy->charging_full_trig_name, "-charging-or-full");
strcpy(psy->charging_trig_name, psy->name);
strcat(psy->charging_trig_name, "-charging");
strcpy(psy->full_trig_name, psy->name);
strcat(psy->full_trig_name, "-full");
led_trigger_register_simple(psy->charging_full_trig_name,
&psy->charging_full_trig);
led_trigger_register_simple(psy->charging_trig_name,
&psy->charging_trig);
led_trigger_register_simple(psy->full_trig_name,
&psy->full_trig);
goto success;
full_failed:
kfree(psy->charging_trig_name);
charging_failed:
kfree(psy->charging_full_trig_name);
charging_full_failed:
rc = -ENOMEM;
success:
return rc;
}
static void power_supply_remove_bat_triggers(struct power_supply *psy)
{
led_trigger_unregister_simple(psy->charging_full_trig);
led_trigger_unregister_simple(psy->charging_trig);
led_trigger_unregister_simple(psy->full_trig);
kfree(psy->full_trig_name);
kfree(psy->charging_trig_name);
kfree(psy->charging_full_trig_name);
return;
}
/* Generated power specific LEDs triggers. */
static void power_supply_update_gen_leds(struct power_supply *psy)
{
union power_supply_propval online;
if (psy->get_property(psy, POWER_SUPPLY_PROP_ONLINE, &online))
return;
dev_dbg(psy->dev, "%s %d\n", __FUNCTION__, online.intval);
if (online.intval)
led_trigger_event(psy->online_trig, LED_FULL);
else
led_trigger_event(psy->online_trig, LED_OFF);
return;
}
static int power_supply_create_gen_triggers(struct power_supply *psy)
{
int rc = 0;
psy->online_trig_name = kmalloc(strlen(psy->name) + sizeof("-online"),
GFP_KERNEL);
if (!psy->online_trig_name)
goto online_failed;
strcpy(psy->online_trig_name, psy->name);
strcat(psy->online_trig_name, "-online");
led_trigger_register_simple(psy->online_trig_name, &psy->online_trig);
goto success;
online_failed:
rc = -ENOMEM;
success:
return rc;
}
static void power_supply_remove_gen_triggers(struct power_supply *psy)
{
led_trigger_unregister_simple(psy->online_trig);
kfree(psy->online_trig_name);
return;
}
/* Choice what triggers to create&update. */
void power_supply_update_leds(struct power_supply *psy)
{
if (psy->type == POWER_SUPPLY_TYPE_BATTERY)
power_supply_update_bat_leds(psy);
else
power_supply_update_gen_leds(psy);
return;
}
int power_supply_create_triggers(struct power_supply *psy)
{
if (psy->type == POWER_SUPPLY_TYPE_BATTERY)
return power_supply_create_bat_triggers(psy);
return power_supply_create_gen_triggers(psy);
}
void power_supply_remove_triggers(struct power_supply *psy)
{
if (psy->type == POWER_SUPPLY_TYPE_BATTERY)
power_supply_remove_bat_triggers(psy);
else
power_supply_remove_gen_triggers(psy);
return;
}
/*
* Sysfs interface for the universal power supply monitor class
*
* Copyright © 2007 David Woodhouse <dwmw2@infradead.org>
* Copyright © 2007 Anton Vorontsov <cbou@mail.ru>
* Copyright © 2004 Szabolcs Gyurko
* Copyright © 2003 Ian Molton <spyro@f2s.com>
*
* Modified: 2004, Oct Szabolcs Gyurko
*
* You may use this code as per GPL version 2
*/
#include <linux/ctype.h>
#include <linux/power_supply.h>
/*
* This is because the name "current" breaks the device attr macro.
* The "current" word resolves to "(get_current())" so instead of
* "current" "(get_current())" appears in the sysfs.
*
* The source of this definition is the device.h which calls __ATTR
* macro in sysfs.h which calls the __stringify macro.
*
* Only modification that the name is not tried to be resolved
* (as a macro let's say).
*/
#define POWER_SUPPLY_ATTR(_name) \
{ \
.attr = { .name = #_name, .mode = 0444, .owner = THIS_MODULE }, \
.show = power_supply_show_property, \
.store = NULL, \
}
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 *status_text[] = {
"Unknown", "Charging", "Discharging", "Not charging", "Full"
};
static char *health_text[] = {
"Unknown", "Good", "Overheat", "Dead", "Over voltage",
"Unspecified failure"
};
static char *technology_text[] = {
"Unknown", "NiMH", "Li-ion", "Li-poly", "LiFe", "NiCd"
};
static char *capacity_level_text[] = {
"Unknown", "Critical", "Low", "Normal", "High", "Full"
};
ssize_t ret;
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 (ret < 0) {
if (ret != -ENODEV)
dev_err(dev, "driver failed to report `%s' property\n",
attr->attr.name);
return ret;
}
if (off == POWER_SUPPLY_PROP_STATUS)
return sprintf(buf, "%s\n", status_text[value.intval]);
else if (off == POWER_SUPPLY_PROP_HEALTH)
return sprintf(buf, "%s\n", health_text[value.intval]);
else if (off == POWER_SUPPLY_PROP_TECHNOLOGY)
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_MODEL_NAME)
return sprintf(buf, "%s\n", value.strval);
return sprintf(buf, "%d\n", value.intval);
}
/* Must be in the same order as POWER_SUPPLY_PROP_* */
static struct device_attribute power_supply_attrs[] = {
/* Properties of type `int' */
POWER_SUPPLY_ATTR(status),
POWER_SUPPLY_ATTR(health),
POWER_SUPPLY_ATTR(present),
POWER_SUPPLY_ATTR(online),
POWER_SUPPLY_ATTR(technology),
POWER_SUPPLY_ATTR(voltage_max_design),
POWER_SUPPLY_ATTR(voltage_min_design),
POWER_SUPPLY_ATTR(voltage_now),
POWER_SUPPLY_ATTR(voltage_avg),
POWER_SUPPLY_ATTR(current_now),
POWER_SUPPLY_ATTR(current_avg),
POWER_SUPPLY_ATTR(charge_full_design),
POWER_SUPPLY_ATTR(charge_empty_design),
POWER_SUPPLY_ATTR(charge_full),
POWER_SUPPLY_ATTR(charge_empty),
POWER_SUPPLY_ATTR(charge_now),
POWER_SUPPLY_ATTR(charge_avg),
POWER_SUPPLY_ATTR(energy_full_design),
POWER_SUPPLY_ATTR(energy_empty_design),
POWER_SUPPLY_ATTR(energy_full),
POWER_SUPPLY_ATTR(energy_empty),
POWER_SUPPLY_ATTR(energy_now),
POWER_SUPPLY_ATTR(energy_avg),
POWER_SUPPLY_ATTR(capacity),
POWER_SUPPLY_ATTR(capacity_level),
POWER_SUPPLY_ATTR(temp),
POWER_SUPPLY_ATTR(temp_ambient),
POWER_SUPPLY_ATTR(time_to_empty_now),
POWER_SUPPLY_ATTR(time_to_empty_avg),
POWER_SUPPLY_ATTR(time_to_full_now),
POWER_SUPPLY_ATTR(time_to_full_avg),
/* Properties of type `const char *' */
POWER_SUPPLY_ATTR(model_name),
POWER_SUPPLY_ATTR(manufacturer),
};
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]);
}