RT-Thread-smart 用户态按键点灯RT-Thread问答社区

smart 用户态按键点灯

发布于 2023-03-01 11:36:24 浏览：879 订阅该版

[tocm]

## 硬件环境
- RDC2022 纪念版开发板

## 点亮 LED 灯

使用过 ART-Pi-smart 的应该都是从灵魂点灯开始的，关于 ART-Pi-smart 上的点灯程序驱动，应该都是使用的 `rt_device_control` `rt_device_write` 的形式来使用的，当然这种方式在 D1s 上也是可以的

下面就是一段 D1s 上的点灯程序，通过用户态编译，烧进开发板后即可运行

```c
#include <rtthread.h>
#include <stdio.h>

#define GET_PIN(PORTx, PIN) (32 * (PORTx - 1) + (PIN & 31))
#define LED_PIN GET_PIN(7, 15) // PG15

/* 由于用户态没有定义这两个结构体，所以这里要重新定义一下，这里要和内核中的定义一直，否则将可能无法运行*/
struct rt_device_pin_mode
{
    rt_base_t pin;
    rt_uint8_t mode;
};
struct rt_device_pin_status
{
    rt_base_t pin;
    rt_uint8_t status;
};

int main()
{
    rt_device_t pin_dev;
    struct rt_device_pin_mode pin_mode;
    struct rt_device_pin_status pin_status;

pin_dev = rt_device_find("pin");
    if (pin_dev == RT_NULL)
    {
        rt_kprintf("not find pin device!\n");
        return -1;
    }
    rt_device_open(pin_dev, RT_DEVICE_OFLAG_RDWR);
    pin_mode.pin = LED_PIN;
    pin_mode.mode = 0;

rt_device_control(pin_dev, 0, (void *)&pin_mode);
    pin_status.pin = LED_PIN;

while (1)
    {
        pin_status.status = 0;
        rt_device_write(pin_dev, 0, (void *)&pin_status, sizeof(pin_status));
        rt_thread_mdelay(200);
        pin_status.status = 1;
        rt_device_write(pin_dev, 0, (void *)&pin_status, sizeof(pin_status));
        rt_thread_mdelay(200);
    }
    rt_device_close(pin_dev);
    return 0;
}
```

通过了解上述程序，可以发现 smart 用户态程序和 rt-thread 基本没有区别，这是由于为了方便用户上手 smart 已经将 rt-thread 部分 api 对接到了用户态中，当然这种开发方式并不适用于所有的 rt-thread api，有些还没有对接完成（就例如下文中提到的按键回调的绑定，由于用户态地址和内核态地址不同的原因，内核态并不能直接调用用户态的函数）

这样的话，又引出了另一种的开发方式，就是像 linux 一样，一切皆文件的形式来去开发，用户态方面使用 [DevFS 设备管理](https://download.rt-thread.org/ci-agent/artifacts/164823/452417/artifacts/docs-online/#/rt-thread-version/rt-thread-smart/device/DevFS/DevFS) 去开发设备,并且官方只推荐这种方式进行设备开发

### 下面就是使用了 DevFS 进行开发的程序

这里分为两个部分

- 内核态设备注册
- 用户态驱动

#### LED 内核态设备注册

```c
#include <rtthread.h>
#include <rtdevice.h>
#include <board.h>
#include <poll.h>
#include <dfs_file.h>

#define GET_PIN(PORTx, PIN) (32 * (PORTx - 1) + (PIN & 31))
#define USER_LED GET_PIN(7, 15) // PG15

static uint8_t is_init;
static uint8_t led_state;
static uint8_t led_state_old;
static rt_device_t device;

static void drv_led_init(void)
{
    rt_pin_mode(USER_LED, PIN_MODE_OUTPUT);
    rt_pin_write(USER_LED, PIN_HIGH);
}

/* Open the led device, and initialize the hardware the first time you open it */
static int drv_led_open(struct dfs_fd *fd)
{
    if (!is_init)
    {
        is_init = 1;
        /* Initialize the hardware */
        drv_led_init();
    }
    /* Increase reference count */
    device->ref_count ++;
    return 0;
}
/* Close the led device, and reset the hardware when the device is no longer in use */
static int drv_led_close(struct dfs_fd *fd)
{
    /* Reduced reference count */
    device->ref_count --;
    /* Reset the hardware when the device is no longer in use */
    if (device->ref_count == 0)
    {
        /* ... */
        is_init = 0;
    }
    return 0;
}

/* Read led state */
static int drv_led_write(struct dfs_fd *fd, const void *buf, size_t count)
{
    if(*(int *)buf == 0)
        rt_pin_write(USER_LED, PIN_HIGH);
    else
        rt_pin_write(USER_LED, PIN_LOW);
    return 1;
}

/*
 * Realize the fops variables.
 */
static struct dfs_file_ops drv_led_fops =
{
    drv_led_open,
    drv_led_close,
    RT_NULL,
    RT_NULL,
    drv_led_write,
    RT_NULL,
    RT_NULL,
    RT_NULL,
    RT_NULL,
};

/*
 * Key device initialization function.
 */
static int rt_hw_led_init(void)
{
    rt_err_t ret;

/* 1. Allocates memory for device structures, Use the calloc function */
    device = rt_calloc(1, sizeof(struct rt_device));
    if (device == RT_NULL)
    {
        return -1;
    }

/* 2. Set to miscellaneous device */
    device->type = RT_Device_Class_Miscellaneous;

/* 3. register a led device */
    ret = rt_device_register(device, "led0", RT_DEVICE_FLAG_RDONLY);
    if (ret != RT_EOK)
    {
        rt_free(device);
        return ret;
    }
    /* 4. set fops */
    device->fops = &drv_led_fops;

return ret;
}
/* Using below macro to export this function, the function will be called automatically after kernel startup */
INIT_DEVICE_EXPORT(rt_hw_led_init);
```

#### LED 用户态驱动

```c
#include <stdio.h>
#include <unistd.h>
#include <fcntl.h>
#include <poll.h>

#define LED0_DEVICE_PATH "/dev/led0"

int main(void)
{
    int led_fd;
    int value = 0;
    int count = 300;
    led_fd = open(LED0_DEVICE_PATH, O_RDWR);
    if (led_fd < 0)
    {
        printf("open device failed\n");
        return -1;
    }

while (1)
    {
        value = 1;
        write(led_fd, &value, 1);
        sleep(1);
        value = 0;
        write(led_fd, &value, 1);
        sleep(1);
    }

close(led_fd);

return 0;
}
```

## 按键控制 LED

上面我们写好了 LED 的内核设备注册和用户态代码，可是 LED 灯只能随时间闪动，是不受我们控制的，那么现在我们要使用按键来去控制 LED 等了

下面，我们来书写按键的内核设备注册代码

#### KEY 内核态设备注册

这里我们使用了 poll 来实现监测按键是否按下，有兴趣的可以查一下 poll 机制

```c
#include <rtthread.h>
#include <rtdevice.h>
#include <board.h>
#include <poll.h>
#include <dfs_file.h>

#define GET_PIN(PORTx, PIN) (32 * (PORTx - 1) + (PIN & 31))
#define USER_KEY GET_PIN(7, 13) // PG13

static uint8_t is_init;
static uint8_t key_state;
static uint8_t key_state_old;
static rt_device_t device;

void irq_callback()
{
    /* enter interrupt */
    key_state = rt_pin_read(USER_KEY);
    rt_interrupt_enter();
    rt_wqueue_wakeup(&(device->wait_queue), (void *)POLLIN);
    /* leave interrupt */
    rt_interrupt_leave();
}

static void drv_key_init(void)
{
    key_state = 1;
    key_state_old = 1;
    rt_pin_mode(USER_KEY, PIN_MODE_INPUT);
    rt_pin_attach_irq(USER_KEY, PIN_IRQ_MODE_RISING_FALLING, irq_callback, RT_NULL);
    rt_pin_irq_enable(USER_KEY, PIN_IRQ_ENABLE);
}

/* Open the key device, and initialize the hardware the first time you open it */
static int drv_key_open(struct dfs_fd *fd)
{
    if (!is_init)
    {
        is_init = 1;
        /* Initialize the hardware */
        drv_key_init();
    }
    /* Increase reference count */
    device->ref_count ++;
    return 0;
}
/* Close the key device, and reset the hardware when the device is no longer in use */
static int drv_key_close(struct dfs_fd *fd)
{
    /* Reduced reference count */
    device->ref_count --;
    /* Reset the hardware when the device is no longer in use */
    if (device->ref_count == 0)
    {
        /* ... */
        is_init = 0;
    }
    return 0;
}

/* Read key state */
static int drv_key_read(struct dfs_fd *fd, void *buf, size_t count)
{
    *(int *)buf = !rt_pin_read(USER_KEY);
    return 1;
}

/* Use poll to check the state of the key */
static int drv_key_poll(struct dfs_fd *fd, struct rt_pollreq *req)
{
    int mask = 0;
    int flags = 0;

/* only support POLLIN */
    flags = fd->flags & O_ACCMODE;
    if (flags == O_RDONLY || flags == O_RDWR)
    {
        /* Add to wait queue, suspend the current thread */
        rt_poll_add(&(device->wait_queue), req);
        /* If the key is pressed, mark a POLLIN event */
        if (key_state != key_state_old)
        {
            key_state_old = key_state;
            mask |= POLLIN;
        }
    }
    return mask;
}

/*
 * Realize the fops variables.
 */
static struct dfs_file_ops drv_key_fops =
{
    drv_key_open,
    drv_key_close,
    RT_NULL,
    drv_key_read,
    RT_NULL,
    RT_NULL,
    RT_NULL,
    RT_NULL,
    drv_key_poll,
};

/*
 * Key device initialization function.
 */
static int rt_hw_key_init(void)
{
    rt_err_t ret;

/* 1. Allocates memory for device structures, Use the calloc function */
    device = rt_calloc(1, sizeof(struct rt_device));
    if (device == RT_NULL)
    {
        return -1;
    }

/* 2. Set to miscellaneous device */
    device->type = RT_Device_Class_Miscellaneous;

/* 3. register a key device */
    ret = rt_device_register(device, "key0", RT_DEVICE_FLAG_RDONLY);
    if (ret != RT_EOK)
    {
        rt_free(device);
        return ret;
    }
    /* 4. set fops */
    device->fops = &drv_key_fops;

return ret;
}
/* Using below macro to export this function, the function will be called automatically after kernel startup */
INIT_DEVICE_EXPORT(rt_hw_key_init);

```

#### 按键控制用户态驱动

上述完成了 KEY LED 的内核设备驱动注册，那么我们内核部分的操作就完成了，下面只需要在用户态对这两个设备进行 read write 等操作，就可以实现对按键和LED灯的控制了

```c
#include <stdio.h>
#include <unistd.h>
#include <fcntl.h>
#include <poll.h>

#define KEY0_DEVICE_PATH "/dev/key0"
#define LED0_DEVICE_PATH "/dev/led0"

int main(void)
{
    int key_fd,led_fd;
    int value = 0;
    struct pollfd fds[1];

/* Open the device by non-blocking mode */
    key_fd = open(KEY0_DEVICE_PATH, O_RDONLY | O_NONBLOCK);
    led_fd = open(LED0_DEVICE_PATH, O_RDWR);
    if (key_fd < 0 || led_fd < 0)
    {
        printf("open device failed\n");
        return -1;
    }

/* Add the key_fd to monitor */
    fds[0].fd = key_fd;
    fds[0].events = POLLIN;

while (1)
    {
        /* Monitor button status, timeout 1S */
        if (poll(fds, 1, 1000) > 0 && fds[0].revents & POLLIN)
        {
            read(key_fd, &value, 1);
            write(led_fd, &value, 1);
        }
    }

close(key_fd);
    close(led_fd);

return 0;
}
```