[经验]

基于Dragonboard 410c的燃气烟雾检测器（二）

2018-9-28 11:48:40

42890 Qualcomm DragonBoard 驱动程序

　　前面已经将做一个燃气烟雾检测器需要用的主要模块介绍了一下，准备好这些模块后，就是硬件连接了，先说一下MQ-2这个模块，它有AO（模拟信号）输出和DO（TTL信号）输出，这里我是接的DO，接下来就是软件上如何去实现了，下面来看一下具体过程：

　　首先来看一下燃气烟雾检测模块MQ-2的底层驱动程序：

#include

#include

#include

#include

#include

#include

#include

#include

#include

#include

#include

#include

#include

#include

#include time.h>

#include

#include

#include

#include

#include

struct mq_data{

int dottl;

int irq;

int d;

int flag;

ktime_t last_ktime;

   ktime_t now_ktime;



struct mutex data_lock;

bool data_ready;

wait_queue_head_t data_queue;

struct work_struct report_work;

struct delayed_work cmd_work;



};

static irqreturn_t mq_interrupt_handler(int irq, void *ptr){

struct mq_data* data = (struct mq_data*)ptr;

if(!gpio_get_value(data->dottl)){

      data->d = 0;

   }else{

      data->d = 1;

}

data->flag = 1;

data-> data_ready = true;

wake_up_interruptible(&data->data_queue);

return IRQ_HANDLED;

}

static void cmd_work_func(struct work_struct* work){

struct mq_data* data = container_of(work,struct mq_data,cmd_work.work);

data-> data_ready = true;

wake_up_interruptible(&data->data_queue);

schedule_delayed_work(&data->cmd_work,msecs_to_jiffies(50));

}

static int parse_dt(struct platform_device* pdev,struct mq_data* data){

int rc;

struct device_node* node = pdev->dev.of_node;

data->dottl = of_get_named_gpio(node,"thunder,dottl",0);

if(gpio_is_valid(data->dottl)){

      rc = gpio_request(data->dottl,"mq_dottl");

      if(rc < 0){

         pr_err("Unable to request dottl gpion");

      }

      gpio_direction_input(data->dottl);

}

return 0;

}

static ssize_t mq_show_value(struct device *dev,

                              struct device_attribute* attr,char* buf){

struct mq_data* data = dev_get_drvdata(dev);

ssize_t lenth;

wait_event_interruptible(data->data_queue,data->data_ready);

data->data_ready = false;

mutex_lock(&data->data_lock);

if(data->flag == 1){

      lenth = sprintf(buf,"%dn",data->d);

}else{

      lenth = sprintf(buf, "%dn", 1);

}

mutex_unlock(&data->data_lock);

return lenth;

}

static DEVICE_ATTR(value,0644,mq_show_value,NULL);

static int mq_probe(struct platform_device *pdev){

struct mq_data* data;

int result;

data = kmalloc(sizeof(struct mq_data),GFP_KERNEL);

if(!data){

      pr_err("%s kmalloc errorn",__FUNCTION__);

      return -ENOMEM;

}

dev_set_drvdata(&pdev->dev,data);

result = parse_dt(pdev,data);

if(result<0){

      pr_err("%s error when parse dtn",__FUNCTION__);

      result = -EINVAL;

      goto err_parse_dt;

}

      data->irq = gpio_to_irq(data->dottl);

      result = request_irq(data->irq,mq_interrupt_handler,IRQF_TRIGGER_RISING|IRQF_TRIGGER_FALLING,"mq_time_count",data);

      if(result<0){

         pr_err("Unable to request irqn");

         goto err_parse_dt;

      }

INIT_DELAYED_WORK(&data->cmd_work,cmd_work_func);

mutex_init(&data->data_lock);

init_waitqueue_head(&data->data_queue);

schedule_delayed_work(&data->cmd_work,msecs_to_jiffies(50));



result=sysfs_create_file(&pdev->dev.kobj,&dev_attr_value.attr);

printk("mq-2 probe successn");

return 0;

err_parse_dt:

kfree(data);

printk("mq-2 probe failedn");

return result;

}

static int mq_remove(struct platform_device *pdev){

return 0;

}

static struct of_device_id mq_match_table[] = {

{ .compatible = "thunder,mq",},

{ },

};

static struct platform_driver mq_driver = {

.probe = mq_probe,

.remove = mq_remove,

.driver = {

      .owner = THIS_MODULE,

      .name = "MQ-2",

      .of_match_table = mq_match_table,

},

};

module_platform_driver(mq_driver);

MODULE_AUTHOR("MQ-2");

MODULE_LICENSE("GPL v2");

节点路径：/sys/bus/platform/drivers/MQ-2/mq-2.66/value

当节点中数值为１时，表示正常，当节点中数值为０时，指示灯被点亮，表示检测到可燃气体或者烟雾。

到此燃气烟雾检测模块MQ-2的底层驱动就完成了。