Beep Platform 驱动开发（miscdevice 框架）

flowchart TD
    A["DTS 节点<br/>compatible = alientek,beep"] --> B[内核创建 platform_device]
    B --> C{"of_device_id 匹配<br/>beep_of_match"}
    C -->|匹配成功| D[调用 beep_probe]
    C -->|无匹配| Z[跳过]

    D --> E["devm_kzalloc<br/>分配 beep_dev 结构体"]
    E --> F["devm_gpiod_get<br/>申请 GPIO5_IO01<br/>初始逻辑低（蜂鸣器关）"]
    F --> G["配置 miscdevice<br/>minor=MISC_DYNAMIC_MINOR<br/>name=beep, fops=&beep_fops"]
    G --> H["misc_register<br/>主设备号 10，动态次设备号"]
    H --> I["/dev/beep 节点自动创建"]
    I --> J["platform_set_drvdata<br/>保存 beep_dev 指针"]

    style A fill:#dae8fc
    style I fill:#d5e8d4
    style Z fill:#f8cecc

classDiagram
    class beep_dev {
        +gpio_desc  *gpiod
        +miscdevice  miscdev
    }
    class miscdevice {
        +int minor
        +const char *name
        +file_operations *fops
        +device *this_device
    }
    class file_operations {
        +open()
        +write()
        +release()
    }
    class gpio_desc {
        <<kernel内部>>
        +GPIO5_IO01
        +极性: ACTIVE_LOW
    }
    class file {
        +void *private_data
    }

    beep_dev *-- miscdevice : 内嵌
    beep_dev *-- gpio_desc : 持有引用（devm_）
    miscdevice --> file_operations : fops 指向
    file ..> miscdevice : ①misc框架设 private_data=miscdev
    file ..> beep_dev  : ②beep_open改 private_data=beep_dev

sequenceDiagram
    participant App  as 用户态 App
    participant VFS  as VFS 层
    participant Misc as misc 框架(misc_open)
    participant Drv  as beep 驱动(beep_open/write)
    participant GPIO as gpiod 子系统

    Note over App,GPIO: 打开设备
    App  ->> VFS  : open("/dev/beep", O_RDWR)
    VFS  ->> Misc : misc_open(inode, filp)
    Misc ->> Misc : filp->private_data = &miscdev
    Misc ->> Drv  : beep_fops.open(inode, filp)
    Drv  ->> Drv  : miscdev = filp->private_data
    Drv  ->> Drv  : dev = container_of(miscdev, beep_dev, miscdev)
    Drv  ->> Drv  : filp->private_data = dev
    Drv  -->> App : fd 返回

    Note over App,GPIO: 控制蜂鸣器（写 "1" 开响）
    App  ->> VFS  : write(fd, "1", 1)
    VFS  ->> Drv  : beep_fops.write(filp, buf, count, ppos)
    Drv  ->> Drv  : dev = filp->private_data
    Drv  ->> Drv  : copy_from_user → val = 1
    Drv  ->> GPIO : gpiod_set_value(dev->gpiod, 1)
    GPIO ->> GPIO : 逻辑 1 + ACTIVE_LOW → 物理低电平
    GPIO -->> App : 蜂鸣器响

    Note over App,GPIO: 关闭蜂鸣器（写 "0"）
    App  ->> VFS  : write(fd, "0", 1)
    VFS  ->> Drv  : beep_fops.write(...)
    Drv  ->> GPIO : gpiod_set_value(dev->gpiod, 0)
    GPIO ->> GPIO : 逻辑 0 + ACTIVE_LOW → 物理高电平
    GPIO -->> App : 蜂鸣器停