Key Platform 驱动开发（中断与定时器消抖）

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

    D --> E["devm_kzalloc<br/>分配 key_dev 结构体"]
    E --> F["devm_gpiod_get<br/>申请 GPIO1_IO18（输入模式）"]
    F --> G["gpiod_to_irq<br/>获取中断号"]
    G --> H["spin_lock_init + setup_timer<br/>初始化自旋锁与消抖定时器"]
    H --> I["devm_request_irq<br/>注册双边沿中断（FALLING|RISING）"]
    I --> J["misc_register<br/>创建 /dev/key"]
    J --> K["platform_set_drvdata<br/>保存 key_dev 指针"]

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

classDiagram
    class key_dev {
        +gpio_desc  *gpiod
        +miscdevice  miscdev
        +timer_list  timer
        +spinlock_t  lock
        +unsigned int irqnum
        +unsigned char key_val
    }
    class miscdevice {
        +int minor
        +const char *name
        +file_operations *fops
    }
    class file_operations {
        +open()
        +read()
    }
    class gpio_desc {
        <<kernel内部>>
        +GPIO1_IO18
        +极性: ACTIVE_LOW
    }
    class timer_list {
        <<kernel内部>>
        +function: key_timer_func
        +expires: jiffies+10ms
    }
    class file {
        +void *private_data
    }

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

sequenceDiagram
    participant App   as 用户态 App
    participant VFS   as VFS 层
    participant Misc  as misc 框架
    participant Drv   as key 驱动
    participant HW    as GPIO 硬件
    participant Timer as 消抖定时器

    Note over App,Timer: ① 打开设备
    App  ->> VFS  : open("/dev/key")
    VFS  ->> Misc : misc_open()
    Misc ->> Misc : filp->private_data = &miscdev
    Misc ->> Drv  : key_open()
    Drv  ->> Drv  : container_of → key_dev
    Drv  ->> Drv  : filp->private_data = key_dev
    Drv  -->> App : fd 返回

    Note over App,Timer: ② 按键按下（异步，与 read 独立）
    HW   ->> Drv  : 下降沿中断 → key_irq_handler
    Drv  ->> Timer: mod_timer(+10ms) 启动消抖
    Note over HW,Timer: 抖动期间中断持续触发，定时器不断重置
    Timer ->> Drv : 10ms 到期 → key_timer_func
    Drv  ->> HW   : gpiod_get_value() = 1（逻辑高=按下）
    Drv  ->> Drv  : spin_lock → key_val = 1 → spin_unlock

    Note over App,Timer: ③ App 读取键值
    App  ->> VFS  : read(fd, buf, 1)
    VFS  ->> Drv  : key_read()
    Drv  ->> Drv  : spin_lock → val = key_val → spin_unlock
    Drv  ->> App  : copy_to_user(val=1) → 返回 1

    Note over App,Timer: ④ 按键松开（异步）
    HW   ->> Drv  : 上升沿中断 → key_irq_handler
    Drv  ->> Timer: mod_timer(+10ms)
    Timer ->> Drv : 10ms 到期 → key_timer_func
    Drv  ->> HW   : gpiod_get_value() = 0（逻辑低=松开）
    Drv  ->> Drv  : spin_lock → key_val = 0 → spin_unlock