以msm8909为例，高通的主要文件有几个：
- qpnp-linear-charger.c(线性充电器)
- qpnp-vm-bms.c（BMS管理）
- power_supply_core.c（power_supply对外部提供对应接口）
其中，vm_bus的power_supply一般为struct power_supply *bms_psy;
而linear-charger则是struct power_supply usb_psy;
（当然这只是一个命名方式而已了）
power_supply具体参考这篇博客：
Linux power supply class(1)_软件架构及API汇整【转】
struct power_supply {
const char *name;
enum power_supply_type type;
enum power_supply_property *properties;
size_t num_properties;
char **supplied_to;
size_t num_supplicants;
char **supplied_from;
size_t num_supplies;
#ifdef CONFIG_OF
struct device_node *of_node;
#endif
int (*get_property)(struct power_supply *psy,
enum power_supply_property psp,
union power_supply_propval *val);
int (*set_property)(struct power_supply *psy,
enum power_supply_property psp,
const union power_supply_propval *val);
int (*property_is_writeable)(struct power_supply *psy,
enum power_supply_property psp);
void (*external_power_changed)(struct power_supply *psy);
void (*set_charged)(struct power_supply *psy);
/* For APM emulation, think legacy userspace. */
int use_for_apm;
/* private */
struct device *dev;
struct work_struct changed_work;
spinlock_t changed_lock;
bool changed;
#ifdef CONFIG_THERMAL
struct thermal_zone_device *tzd;
struct thermal_cooling_device *tcd;
#endif
#ifdef CONFIG_LEDS_TRIGGERS
struct led_trigger *charging_full_trig;
char *charging_full_trig_name;
struct led_trigger *charging_trig;
char *charging_trig_name;
struct led_trigger *full_trig;
char *full_trig_name;
struct led_trigger *online_trig;
char *online_trig_name;
struct led_trigger *charging_blink_full_solid_trig;
char *charging_blink_full_solid_trig_name;
#endif
};
获取电量百分比改变：
在vm_bus.c中一般都有power_supply_changed()函数来改变其节点属性；
power_supply_changed(&chip->bms_psy);(qpnp-vm-bms.c) --> power_supply_changed()中有一个工作队列schedule_work(&psy->changed_work);(power_supply_core.c)--> power_supply_changed_work()工作队列--> class_for_each_device(power_supply_class, NULL, psy,__power_supply_changed_work);对power_supply_class下的每个设备都进行匹配 --> __power_supply_changed_work调用psy->external_power_changed中的函数--> qpnp_vm_bms_ext_power_changed是bms_psy.external_power_changed注册的回调函数;
qpnp_vm_bms_ext_power_changed则是获取电池的状态，根据各个函数来判断；
获取电量值：
power supply class将所有可能PSY属性，以枚举型变量形式抽象出来，PSY driver可以根据设备的实际情况，从中选取一些。
enum power_supply_property {
/* Properties of type `int' */
POWER_SUPPLY_PROP_STATUS = 0, //该PSY的status，主要是充电状态，包括：unknown,charging,discharging,not charging full,
POWER_SUPPLY_PROP_CHARGE_TYPE,//充电类型
POWER_SUPPLY_PROP_HEALTH, //健康状况，包括：good dead over voltage等
POWER_SUPPLY_PROP_PRESENT, //电量百分比
POWER_SUPPLY_PROP_ONLINE, //是否在线
POWER_SUPPLY_PROP_AUTHENTIC,
POWER_SUPPLY_PROP_TECHNOLOGY, //采用的技术
POWER_SUPPLY_PROP_CYCLE_COUNT,
POWER_SUPPLY_PROP_VOLTAGE_MAX,
POWER_SUPPLY_PROP_VOLTAGE_MIN,
POWER_SUPPLY_PROP_VOLTAGE_MAX_DESIGN,
POWER_SUPPLY_PROP_VOLTAGE_MIN_DESIGN,
POWER_SUPPLY_PROP_VOLTAGE_NOW,
POWER_SUPPLY_PROP_VOLTAGE_AVG,
POWER_SUPPLY_PROP_VOLTAGE_OCV,
POWER_SUPPLY_PROP_CURRENT_MAX,
POWER_SUPPLY_PROP_CURRENT_NOW,
POWER_SUPPLY_PROP_CURRENT_AVG,
POWER_SUPPLY_PROP_POWER_NOW,
POWER_SUPPLY_PROP_POWER_AVG,
POWER_SUPPLY_PROP_CHARGE_FULL_DESIGN,
POWER_SUPPLY_PROP_CHARGE_EMPTY_DESIGN,
POWER_SUPPLY_PROP_CHARGE_FULL,
POWER_SUPPLY_PROP_CHARGE_EMPTY,
POWER_SUPPLY_PROP_CHARGE_NOW,
POWER_SUPPLY_PROP_CHARGE_AVG,
POWER_SUPPLY_PROP_CHARGE_COUNTER,
POWER_SUPPLY_PROP_CONSTANT_CHARGE_CURRENT,
POWER_SUPPLY_PROP_CONSTANT_CHARGE_CURRENT_MAX,
POWER_SUPPLY_PROP_CONSTANT_CHARGE_VOLTAGE,
POWER_SUPPLY_PROP_CONSTANT_CHARGE_VOLTAGE_MAX,
POWER_SUPPLY_PROP_CHARGE_CONTROL_LIMIT,
POWER_SUPPLY_PROP_CHARGE_CONTROL_LIMIT_MAX,
POWER_SUPPLY_PROP_ENERGY_FULL_DESIGN,
POWER_SUPPLY_PROP_ENERGY_EMPTY_DESIGN,
POWER_SUPPLY_PROP_ENERGY_FULL,
POWER_SUPPLY_PROP_ENERGY_EMPTY,
POWER_SUPPLY_PROP_ENERGY_NOW,
POWER_SUPPLY_PROP_ENERGY_AVG,
POWER_SUPPLY_PROP_CAPACITY, /* in percents! */
POWER_SUPPLY_PROP_CAPACITY_ALERT_MIN, /* in percents! */
POWER_SUPPLY_PROP_CAPACITY_ALERT_MAX, /* in percents! */
POWER_SUPPLY_PROP_CAPACITY_LEVEL, //容量
POWER_SUPPLY_PROP_TEMP,
POWER_SUPPLY_PROP_TEMP_ALERT_MIN,
POWER_SUPPLY_PROP_TEMP_ALERT_MAX,
POWER_SUPPLY_PROP_TEMP_AMBIENT,
POWER_SUPPLY_PROP_TEMP_AMBIENT_ALERT_MIN,
POWER_SUPPLY_PROP_TEMP_AMBIENT_ALERT_MAX,
POWER_SUPPLY_PROP_TIME_TO_EMPTY_NOW,
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 */
POWER_SUPPLY_PROP_SCOPE,
/* Local extensions */
POWER_SUPPLY_PROP_USB_HC,
POWER_SUPPLY_PROP_USB_OTG,
POWER_SUPPLY_PROP_CHARGE_ENABLED,
/* Local extensions of type int64_t */
POWER_SUPPLY_PROP_CHARGE_COUNTER_EXT,
/* Properties of type `const char *' */
POWER_SUPPLY_PROP_MODEL_NAME,
POWER_SUPPLY_PROP_MANUFACTURER,
POWER_SUPPLY_PROP_SERIAL_NUMBER,
};
根据属性来判断：
qpnp-linear-charger.c中的chip->bms_psy->get_property(qpnp-linear-charger.c)————> qpnp_vm_bms_power_get_property————> get_prop_bms_capacity
设置电量：
以设置充电状态为例，POWER_SUPPLY_STATUS_CHARGING为其power_supply需要设置的状态，并且使用POWER_SUPPLY_PROP_STATUS来确定设置的东西：
vm_bus只有在复充的时候会会设置充电，其他情况都只有linear-charge充电器中使用：
ret.intval = POWER_SUPPLY_STATUS_CHARGING;
rc = chip->batt_psy->set_property(chip->batt_psy,
POWER_SUPPLY_PROP_STATUS, &ret);