设备树驱动API【原创】

 #include <linux/init.h>
 #include <linux/module.h>
 #include <linux/of.h>
 #include <linux/of_irq.h>
 #include <linux/interrupt.h>

 #define U32_DATA_LEN 4

 static  int is_good;
 static int irqno;

 irqreturn_t key_irq_handler(int irqno, void *devid)
 {
     printk("------------------------key pressed \n");
     return IRQ_HANDLED;
 }

 static int __init dt_drv_init(void)
 {
     /*
          test_nod@12345678{
                 compatible = "farsight,test";
                 reg = <0x12345678 0x24
                         0x87654321 0x24>;
                 testprop,mytest;
                 test_list_string = "red fish","fly fish", "blue fish";
                  interrupt-parent = <&gpx1>;
                 interrupts = <1 4>;

         };
     */

     // 在代码中获取节点的所有信息
     //先把节点获取到
     struct device_node *np = NULL;

     np = of_find_node_by_path("/test_nod@12345678");
     if(np){
         printk("find test node ok\n");
         printk("node name = %s\n", np->name);
         printk("node full name = %s\n", np->full_name);

     }else{
         printk("find test node failed\n");

     }

     //获取到节点中的属性
     struct property *prop = NULL;
     prop = of_find_property(np, "compatible",NULL);
     if(prop)
     {
         printk("find compatible ok\n");
         printk("compatible value = %s\n", prop->value);
         printk("compatible name = %s\n", prop->name);
     }else{
         printk("find compatible failed\n");

     }

     if(of_device_is_compatible(np, "farsight,test"))
     {
         printk("we have a compatible named farsight,test\n");
     }

     //读取到属性中的整数的数组

     u32 regdata[U32_DATA_LEN];
     int ret;

     ret = of_property_read_u32_array(np, "reg", regdata, U32_DATA_LEN);
     if(!ret)
     {
         int i;
         for(i=; i<U32_DATA_LEN; i++)
             printk("----regdata[%d] = 0x%x\n", i,regdata[i]);

     }else{
         printk("get reg data failed\n");
     }

     //读取到属性中的字符串的数组
     const char *pstr[];

     int i;
     for(i=; i<; i++)
     {
         ret = of_property_read_string_index(np, "test_list_string", i, &pstr[i]);
         if(!ret)
         {
             printk("----pstr[%d] = %s\n", i,pstr[i]);
         }else{
             printk("get pstr data failed\n");
         }
     }

     // 属性的值为空，实际可以用于设置标志
     if(of_find_property(np, "testprop,mytest", NULL))
     {
             is_good = ;
             printk("is_good = %d\n", is_good);
     }

     // 获取到中断的号码
     irqno = irq_of_parse_and_map(np, );
     printk("-----irqno = %d\n", irqno);

     //验证中断号码是否有效
     ret = request_irq(irqno, key_irq_handler, IRQF_TRIGGER_FALLING|IRQF_TRIGGER_RISING,
                 "key_irq", NULL);
     if(ret)
     {
         printk("request_irq error\n");
         return -EBUSY;
     }

     return ;

 }

 static void __exit dt_drv_exit(void)
 {
     free_irq(irqno,  NULL);

 }

 module_init(dt_drv_init);
 module_exit(dt_drv_exit);
 MODULE_LICENSE("GPL");