linux of函数实例

/ {
    wanghb {
        gpio = <129>;
        gpios = <129 130 131>;
        args = "wanghbargs";
            compatible = "wanghbcompatible";
        child1@0x1000012{
            args = "child1"; 
            gpios = <120>;
        };
        child2@0x1000012{
            args = "child2"; 
            gpios = <121>;
        };
    };
    
    
    zmm@0x120000{
        args = "zmm";
        gpios = <120>;
    };
};

主要来练习 of_find_node_by_path， of_find_node_by_name，of_property_read_u32_array ，of_property_read_string ，of_property_count_elems_of_size ， of_get_next_child ，of_get_parent 函数

#include <linux/of.h>
#include <linux/device.h>
#include <linux/platform_device.h>
#include <linux/err.h>
#include <linux/errno.h>
#include <linux/list.h>
#include <linux/init.h>
#include <linux/module.h>
#include <linux/kernel.h>


struct device_node * utils_find_node_by_path(char * node_path)
{
    struct device_node * node = NULL;
    node  = of_find_node_by_path(node_path);
    if(node != NULL)
    {
        printk(KERN_INFO "[success find device_node ,%s]
",node_path);
    }
    else
    {
        printk(KERN_INFO "[could not find device_node ,%s]
",node_path);
    }
    return node;
}
struct device_node * utils_find_node_by_name(char * node_name)
{
    struct device_node * node = NULL;
    node  = of_find_node_by_name(NULL,node_name);
    if(node != NULL)
    {
        printk(KERN_INFO "[success find device_node ,%s]
",node_name);
    }
    else
    {
        printk(KERN_INFO "[could not find device_node ,%s]
",node_name);
    }
    return node;
}
static int __init test_module_init(void)
{
    
    struct device_node *  wanghb = NULL;
    struct device_node *  zmm = NULL;
    struct device_node *  parent = NULL;
    struct device_node *  child = NULL;
    struct property *     wanghb_args = NULL;
    u32 value_array[10] = {0};
    u32 size = 0;
    const char * string ;
    const char * string1 ;
    const char * string2 ;
    god_bless();
    wanghb  = utils_find_node_by_path("/wanghb");
    wanghb  = utils_find_node_by_name("wanghb");
    zmm     = utils_find_node_by_path("/zmm@0x120000");
    zmm     = utils_find_node_by_name("zmm@0x120000");
    zmm     = utils_find_node_by_name("zmm");
    printk(KERN_INFO "====================================================================================");
    wanghb_args = of_find_property(wanghb,"args",NULL);
    printk(KERN_INFO "[wanghb_args value : %s, name :%s]
",(char*)wanghb_args->value,(char*)wanghb_args->name);
    wanghb_args = of_find_property(wanghb,"compatible",NULL);
    printk(KERN_INFO "[compatible value : %s, name :%s]
",(char*)wanghb_args->value,(char*)wanghb_args->name);
    
    of_property_read_string(wanghb,"args",&string);
    printk(KERN_INFO "[args : %s, ]
",string);
    
    of_property_read_string(wanghb,"compatible",&string);
    printk(KERN_INFO "[compatible : %s, ]
",string);
    
    of_property_read_u32_array(wanghb,"gpio",value_array,1);
    printk(KERN_INFO "[gpio : %d]
",value_array[0]);
    
    of_property_read_u32_array(wanghb,"gpios",value_array,3);
    printk(KERN_INFO "[gpio [0]: %d ,gpio [1]: %d ,gpio [2]: %d ]
",value_array[0],value_array[1],value_array[2]);
    
    size = of_property_count_elems_of_size(wanghb, "gpios", sizeof(u32));
    printk(KERN_INFO "[size : %d]
",size);
    
    child = of_get_next_child(wanghb,NULL);
    if(child)
    {
        of_property_read_string(child,"args",&string1);
        printk(KERN_INFO "[args : %s]
",string1);
        
        child = of_get_next_child(child,child);
        of_property_read_string(child,"args",&string2);
        printk(KERN_INFO "[args : %s]
",string2);
    }
    else
    {
        printk(KERN_ERR "[could not find childnode ]
");
    }
    
    parent = of_get_parent(child);
    of_property_read_string(parent,"args",&string);
    printk(KERN_INFO "[parentargs : %s]
",string);
    
    printk(KERN_INFO "====================================================================================");
    return 0;
}

static void test_module_exit(void)
{
}
module_init(test_module_init);
module_exit(test_module_exit);

MODULE_AUTHOR("wanghb");
MODULE_LICENSE("GPL");

结果如下：