Linux电源管理(2)

System PMIC
  1. Regulator驱动
  2. OPP
  3. PM QoS

Regulator驱动

Regulator是Linux系统中电源管理的基础设施之一，用于稳压电源的管理，是各种驱动子系统中设置电压的标准接口。

一般在ARM板上，各个稳压器(Low Dropout Regulator, LDO,低压差线性稳压器)和设备会形成一个Regulator树形结构。

Regulator树形结构

内核中用regulator_desc结构体来对稳压器的属性和操作进行了封装。

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struct regulator_desc {
    const char *name;
    const char *supply_name;
    const char *of_match;
    const char *regulators_node;
    int (*of_parse_cb)(struct device_node *,
                const struct regulator_desc *,
                struct regulator_config *);
    int id;
    unsigned int continuous_voltage_range:1;
    unsigned n_voltages;
    unsigned int n_current_limits;
    const struct regulator_ops *ops;
    int irq;
    enum regulator_type type;
    struct module *owner;

    unsigned int min_uV;
    unsigned int uV_step;
    unsigned int linear_min_sel;
    int fixed_uV;
    unsigned int ramp_delay;
    int min_dropout_uV;

    const struct regulator_linear_range *linear_ranges;
    const unsigned int *linear_range_selectors;

    int n_linear_ranges;

    const unsigned int *volt_table;
    const unsigned int *curr_table;

    unsigned int vsel_range_reg;
    unsigned int vsel_range_mask;
    unsigned int vsel_reg;
    unsigned int vsel_mask;
    unsigned int vsel_step;
    unsigned int csel_reg;
    unsigned int csel_mask;
    unsigned int apply_reg;
    unsigned int apply_bit;
    unsigned int enable_reg;
    unsigned int enable_mask;
    unsigned int enable_val;
    unsigned int disable_val;
    bool enable_is_inverted;
    unsigned int bypass_reg;
    unsigned int bypass_mask;
    unsigned int bypass_val_on;
    unsigned int bypass_val_off;
    unsigned int active_discharge_on;
    unsigned int active_discharge_off;
    unsigned int active_discharge_mask;
    unsigned int active_discharge_reg;
    unsigned int soft_start_reg;
    unsigned int soft_start_mask;
    unsigned int soft_start_val_on;
    unsigned int pull_down_reg;
    unsigned int pull_down_mask;
    unsigned int pull_down_val_on;

    unsigned int enable_time;

    unsigned int off_on_delay;

    unsigned int (*of_map_mode)(unsigned int mode);
};

而Regulator驱动的实现可以说就是对于regulator_desc结构的填充以及相应操作的实现。为此Regulator子系统提供了如下这些标准API。

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struct regulator_dev *
regulator_register(const struct regulator_desc *regulator_desc,
           const struct regulator_config *config);
struct regulator_dev *
devm_regulator_register(struct device *dev,
            const struct regulator_desc *regulator_desc,
            const struct regulator_config *config);
void regulator_unregister(struct regulator_dev *rdev);
void devm_regulator_unregister(struct device *dev, struct regulator_dev *rdev);

int regulator_notifier_call_chain(struct regulator_dev *rdev,
                  unsigned long event, void *data);

OPP

如今的SoC都包含了很多集成组件，各个模块运行的状态要求都不一样。如某些domain可以运行在较低的频率和电压下，而其它domain可以运行在较高的频率和电压下，而domain所支持的\<频率，电压>对的集合称为OPP(Operating Performance Point)。

PM QoS

内核中PM Qos系统针对内核和应用程序提供了一套接口，通过这个接口，用户可以设定自身对性能的期望。

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int pm_qos_update_target(struct pm_qos_constraints *c, struct plist_node *node,
             enum pm_qos_req_action action, int value);
bool pm_qos_update_flags(struct pm_qos_flags *pqf,
             struct pm_qos_flags_request *req,
             enum pm_qos_req_action action, s32 val);
void pm_qos_add_request(struct pm_qos_request *req, int pm_qos_class,
            s32 value);
void pm_qos_update_request(struct pm_qos_request *req,
               s32 new_value);
void pm_qos_update_request_timeout(struct pm_qos_request *req,
                   s32 new_value, unsigned long timeout_us);
void pm_qos_remove_request(struct pm_qos_request *req);

int pm_qos_request(int pm_qos_class);
int pm_qos_add_notifier(int pm_qos_class, struct notifier_block *notifier);
int pm_qos_remove_notifier(int pm_qos_class, struct notifier_block *notifier);
int pm_qos_request_active(struct pm_qos_request *req);
s32 pm_qos_read_value(struct pm_qos_constraints *c);

enum pm_qos_flags_status __dev_pm_qos_flags(struct device *dev, s32 mask);
enum pm_qos_flags_status dev_pm_qos_flags(struct device *dev, s32 mask);
s32 __dev_pm_qos_resume_latency(struct device *dev);
s32 dev_pm_qos_read_value(struct device *dev, enum dev_pm_qos_req_type type);
int dev_pm_qos_add_request(struct device *dev, struct dev_pm_qos_request *req,
               enum dev_pm_qos_req_type type, s32 value);
int dev_pm_qos_update_request(struct dev_pm_qos_request *req, s32 new_value);
int dev_pm_qos_remove_request(struct dev_pm_qos_request *req);
int dev_pm_qos_add_notifier(struct device *dev,
                struct notifier_block *notifier,
                enum dev_pm_qos_req_type type);
int dev_pm_qos_remove_notifier(struct device *dev,
                   struct notifier_block *notifier,
                   enum dev_pm_qos_req_type type);
void dev_pm_qos_constraints_init(struct device *dev);
void dev_pm_qos_constraints_destroy(struct device *dev);
int dev_pm_qos_add_ancestor_request(struct device *dev,
                    struct dev_pm_qos_request *req,
                    enum dev_pm_qos_req_type type, s32 value);
int dev_pm_qos_expose_latency_limit(struct device *dev, s32 value);
void dev_pm_qos_hide_latency_limit(struct device *dev);
int dev_pm_qos_expose_flags(struct device *dev, s32 value);
void dev_pm_qos_hide_flags(struct device *dev);
int dev_pm_qos_update_flags(struct device *dev, s32 mask, bool set);
s32 dev_pm_qos_get_user_latency_tolerance(struct device *dev);
int dev_pm_qos_update_user_latency_tolerance(struct device *dev, s32 val);
int dev_pm_qos_expose_latency_tolerance(struct device *dev);
void dev_pm_qos_hide_latency_tolerance(struct device *dev);

QoS的特性用于CPUIdle子系统的状态切换的判断中，而驱动或系统应用则可以利用上面的一系列API对QoS进行设置、更新和调整。

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文章标题:Linux电源管理(2)

本文作者:红尘追风

发布时间:2017-01-17, 19:21:49

原始链接:http://www.micernel.com/2017/01/17/Linux%E7%94%B5%E6%BA%90%E7%AE%A1%E7%90%86(2)/

版权声明: "署名-非商用-相同方式共享 4.0" 转载请保留原文链接及作者。

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