基于i2c-dev.c与i2c client交互的应用程序

linux kernel version：4.4.38

hardware platform： exynos4412-tiny4412

基于i2c-dev.c写应用程序，在用户空间与i2c设备交互  

  1 #include <stdio.h>  
  2 #include<stdlib.h>
  3 #include<string.h>
  4 #include <errno.h>
  5 #include <unistd.h>
  6 #include <sys/ioctl.h>
  7 #include <sys/types.h>
  8 #include <sys/stat.h>
  9 #include <fcntl.h>
 10 #include <linux/i2c.h>
 11 #include <linux/i2c-dev.h>
 12 
 13 // my_i2c_app [adapter number] [client addr] [r] [register addr] 
 14 // my_i2c_app [adapter number] [client addr] [w] [register addr] [register value]
　　//eg: ./my_i2c_app 0x3 0x4c w 0x8 0x4
　　//eg: ./my_i2c_app 0x3 0x4c r 0x8

 15 #define I2C_ADAPTER_FORMAT "/dev/i2c-%d"
 16 #define I2C_WRIRE   0
 17 #define I2C_READ    1
 18 
 19 struct i2c_rdwr_ioctl_data work_queue;
 20 unsigned char adapter_addr = 0;
 21 unsigned char client_addr = 0;
 22 unsigned char register_addr = 0;
 23 unsigned char flags = 0;
 24 unsigned char register_value = 0;
 25 //解析参数，这里图省事，定义了全局变量
 26 int analyse_parse(int argc, char *argv[]){
 27 
 28     if(argc < 5){
 29         return -1;
 30     }
 31 
 32     adapter_addr = strtoul(argv[1], NULL, 16);
 33     client_addr = strtoul(argv[2], NULL, 16);
 34     register_addr = strtoul(argv[4], NULL, 16);
 35 
 36     if(argv[3][0] == 'w'){
 37         flags = I2C_WRIRE;
 38         register_value = strtoul(argv[5], NULL, 16);
 39     }
 40     else {
 41         flags = I2C_READ;
 42     }
 43 
 44     printf("i2c client adapter [0x%02x]\n", adapter_addr);
 45     printf("i2c client address [0x%02x]\n", client_addr);
 46     printf("i2c register address [0x%02x]\n", register_addr);
 47     printf("i2c register value [0x%02x]\n", register_value);
 48     printf("i2c flags [0x%02x]\n", flags);
 49     return 0;
 50 }
 51 
 52 int create_ioctl_data(void)
 53 {
 54 　　//malloc 两个i2c_msg,因为写只需要一个i2c_msg就ok，但是读需要两个
 55     work_queue.nmsgs = 2;
 56     work_queue.msgs = (struct i2c_msg *)malloc(work_queue.nmsgs * sizeof(struct i2c_msg));
 57     work_queue.msgs[0].buf = (unsigned char *)malloc(8 * sizeof(unsigned char));
 58     work_queue.msgs[1].buf = (unsigned char *)malloc(8 * sizeof(unsigned char));
 59 
 60     if(work_queue.msgs == NULL || work_queue.msgs[0].buf == NULL || work_queue.msgs[1].buf == NULL){
 61         return -1;
 62     }
 63 
 64     if(flags == I2C_WRIRE){
 65         //write
 66         work_queue.nmsgs  = 1; 
 67         (work_queue.msgs[0]).flags = I2C_WRIRE;//write  
 68         (work_queue.msgs[0]).addr = client_addr;  
 69         (work_queue.msgs[0]).len = 2;  
 70         (work_queue.msgs[0]).buf[0] = register_addr;//因为上面buf已经分配过了
 71         (work_queue.msgs[0]).buf[1] = register_value;//因为上面buf已经分配过了 
 72     }
 73     else {
 74         //read
 75         work_queue.nmsgs  = 2; 
 76         (work_queue.msgs[0]).flags = I2C_WRIRE;//write  
 77         (work_queue.msgs[0]).addr = client_addr;  
 78         (work_queue.msgs[0]).len = 1;  
 79         (work_queue.msgs[0]).buf[0] = register_addr;//因为上面buf已经分配过了  
 80 
 81         (work_queue.msgs[1]).flags = I2C_READ;//read 
 82         (work_queue.msgs[1]).addr = client_addr;  
 83         (work_queue.msgs[1]).len = 1;    
 84         (work_queue.msgs[1]).buf[0] = 0; //memset
 85     }
 86     return 0;
 87 }
 88 
 89 void free_memory(void)
 90 {
 91     free(work_queue.msgs[0].buf);
 92     free(work_queue.msgs[1].buf);
 93     free(work_queue.msgs);  
 94     return ;
 95 }
 96 
 97 int main(int argc, char *argv[])
 98 {
 99     int ret;
100     int fd;
101     int i;
102     unsigned char file_name[32];
103 
104     ret = analyse_parse(argc, argv);
105     if(ret < 0){
106         printf("param error!!!");
107         return -1;
108     }
109 
110     ret = create_ioctl_data();
111     if(ret < 0){
112         printf("create_ioctl_data error!!!");
113         return -1;
114     }
115 
116     memset(file_name, 0, sizeof(file_name));
117     snprintf(file_name, sizeof(file_name), I2C_ADAPTER_FORMAT, adapter_addr);
118 
119     fd = open(file_name, O_RDWR);
120     if(fd < 0){
121         perror("open");
122         return -1;
123     }
124 
125     //set i2c client address
126     ret = ioctl(fd, I2C_SLAVE, client_addr);
127     if(ret < 0){
128         perror("ioctl");
129         return -1;        
130     }
131 　　//经测试，写的时候用write系统调用ok，读的时候read不行
　　　　//read系统调用不能repeat start

132     ret = ioctl(fd, I2C_RDWR, (unsigned long)&work_queue); 
133     printf("%s %d ret=%d\n", __FUNCTION__, __LINE__, ret);
134     if(flags == I2C_WRIRE){
135         //write
136         printf("i2c client addr [0x%02x] reg_address [0x%02x] data [0x%02x]\n", client_addr, register_addr, work_queue.msgs[0].buf[1]);
137     }
138     else {
139         //read
140         printf("i2c client addr [0x%02x] reg_address [0x%02x] data [0x%02x]\n", client_addr, register_addr, work_queue.msgs[1].buf[0]);
141     }
142 
143     close(fd);
144     free_memory();
145     return ret;
146 
147 }

 

posted @ 2021-05-12 16:46  王东力  阅读(155)  评论(0)    收藏  举报