基于Dragonboard 410c的燃气烟雾检测器（四）

最新推荐文章于 2018-02-28 13:35:05 发布

原创最新推荐文章于 2018-02-28 13:35:05 发布 · 759 阅读

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CC 4.0 BY-SA版权

本文介绍了一种用于嵌入式系统的红灯报警模块驱动程序的实现方法，该驱动支持通过sysfs接口进行交互，便于上层软件进行状态设置与获取。

　　前面已经简单的将燃气烟雾检测模块MQ-2和温湿度检测模块dht11的底层驱动实现了，下面再加一个简单的红灯的驱动，用于报警：

#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/init.h>
#include <linux/slab.h>
#include <linux/interrupt.h>
#include <linux/sysfs.h>
#include <linux/delay.h>
#include <linux/platform_device.h>
#include <linux/err.h>
#include <linux/input.h>
#include <linux/mutex.h>
#include <linux/ctype.h>
#include <linux/pm_runtime.h>
#include <linux/device.h>
#include <linux/irq.h>
#include <linux/of_gpio.h>

#include <linux/wait.h>
#include <asm/uaccess.h>

struct red_data{
   int pin;
   int d;
    struct mutex data_lock;
};

static int parse_dt(struct platform_device* pdev,struct red_data* data){
   int rc;
   struct device_node* node = pdev->dev.of_node;
   data->pin = of_get_named_gpio(node,"thunder,pin",0);
   if(gpio_is_valid(data->pin)){
       rc = gpio_request(data->pin,"red_pin");
       if(rc < 0){
           pr_err("Unable to request pin gpio\n");
       }
       gpio_direction_output(data->pin, 1);
       data->d = 1;
   }
   return 0;
}

static ssize_t red_store_value(struct device *dev,
                struct device_attribute *attr,
                const char *buf, size_t size){
    struct red_data* data = dev_get_drvdata(dev);
   int da = simple_strtoul(buf,NULL,10);
   if(da == 1){
       gpio_set_value(data->pin, 1);
   }else{
       gpio_set_value(data->pin, 0);
   }
   data->d = da;
    return size;
}

static ssize_t red_show_value(struct device *dev,
                                  struct device_attribute* attr,char* buf){
    struct red_data* data = dev_get_drvdata(dev);
    ssize_t da;
    mutex_lock(&data->data_lock);
   da = sprintf(buf, "%d\n", data->d);
    mutex_unlock(&data->data_lock);
    return da;
}

static DEVICE_ATTR(value,0644,red_show_value,red_store_value);

static int red_probe(struct platform_device *pdev){
   struct red_data* data;
   int result;
   data = kmalloc(sizeof(struct red_data),GFP_KERNEL);
   if(!data){
       pr_err("%s kmalloc error\n",__FUNCTION__);
       return -ENOMEM;
   }
   dev_set_drvdata(&pdev->dev,data);
   result = parse_dt(pdev,data);
   if(result<0){
       pr_err("%s error when parse dt\n",__FUNCTION__);
       result = -EINVAL;
       goto err_parse_dt;
   }

    mutex_init(&data->data_lock);

   result=sysfs_create_file(&pdev->dev.kobj,&dev_attr_value.attr);
   printk("red probe success\n");
   return 0;
err_parse_dt:
   kfree(data);
   printk("red probe failed\n");
   return result;
}
static int red_remove(struct platform_device *pdev){
   return 0;
}

static struct of_device_id red_match_table[] = {
   { .compatible = "thunder,red",},
   { },
};

static struct platform_driver red_driver = {
   .probe = red_probe,
   .remove = red_remove,
   .driver = {
       .owner = THIS_MODULE,
       .name = "red",
       .of_match_table = red_match_table,
   },
};

module_platform_driver(red_driver);
MODULE_AUTHOR("RED");
MODULE_LICENSE("GPL v2");

节点路径：/sys/bus/platform/drivers/red/rgb_red.64/value

这个节点是可读可写的，当节点值为０，灯亮报警；当节点值为１等灭，正常。