Add userspace I2C read-write tool (I2c-util) in the Android source tree

Through the/dev/i2c-n node, the user can directly access the I2C peripheral registers on the userspace board, mainly through i2c_rdwr this IO control command to pass i2c_msg array to kernel to execute. The following code can complete this function:

#include <stdio.h> #include <linux/types.h> #include <fcntl.h> #include <unistd.h> #include <stdlib.h> #include <sys/types.h> #include <sys/ioctl.h> #include <errn o.h> #include <assert.h> #include <string.h> #include <linux/i2c.h>/* This is the structure as used in the I2C_RDWR IOCTL call */struct I2c_rdwr_ioctl_data {struct i2c_msg    __user *msgs;                    /* Pointers to I2C_MSGS * * __u32 nmsgs;     
         
/* Number of I2C_MSGS */}; int I2c_read_reg (char *dev, unsigned char *buf, unsigned slave_address, unsigned reg_address, int len) {str     
    UCT I2c_rdwr_ioctl_data Work_queue;     
    unsigned char w_val = reg_address;     
         
    int ret;     
    int fd = open (dev, o_rdwr);     
        if (!FD) {printf ("Error on opening the device file\n");     
    return 0; }     
         
    WORK_QUEUE.NMSGS = 2;     
    Work_queue.msgs = (struct i2c_msg*) malloc (work_queue.nmsgs *sizeof (struct i2c_msg));     
        if (!work_queue.msgs) {printf ("Memory alloc error\n");     
        Close (FD);     
    return 0;     
    } IOCTL (FD, I2c_timeout, 2);     
         
    IOCTL (FD, i2c_retries, 1);     
    (Work_queue.msgs[0]). len = 1;     
    (Work_queue.msgs[0]). addr = slave_address;     
         
    (Work_queue.msgs[0]). BUF = &w_val;     
    (Work_queue.msgs[1]). len = len;     
    (Work_queue.msgs[1]). Flags = I2C_M_RD;     
    (Work_queue.msgs[1]). addr = slave_address;     
         
    (Work_queue.msgs[1]). buf = BUF;     
    RET = IOCTL (FD, I2C_RDWR, (unsigned long) &work_queue);     
        if (Ret < 0) {printf ("error during I2C_RDWR IOCTL with error code:%d\n", ret);     
        Close (FD);     
        Free (WORK_QUEUE.MSGS);     
    return 0;   } else {  
        printf ("Read salve:%02x reg:%02x\n", slave_address, reg_address);     
        Close (FD);     
        Free (WORK_QUEUE.MSGS);     
    return Len;  } int I2c_write_reg (char *dev, unsigned char *buf, unsigned slave_address, unsigned reg_address, int     
    Len) {struct I2c_rdwr_ioctl_data work_queue;     
    unsigned char w_val = reg_address;     
    unsigned char w_buf[len+1];     
         
    int ret;     
         
    W_buf[0] = reg_address;     
    int fd = open (dev, o_rdwr);     
        if (!FD) {printf ("Error on opening the device file\n");     
    return 0;     
    } work_queue.nmsgs = 1;     
    Work_queue.msgs = (struct i2c_msg*) malloc (work_queue.nmsgs *sizeof (struct i2c_msg));     
        if (!work_queue.msgs) {printf ("Memory alloc error\n");     
        Close (FD);     
    return 0;     
    } IOCTL (FD, I2c_timeout, 2); IOctl (FD, i2c_retries, 1);     
    (Work_queue.msgs[0]). Len = 1 + len;     
    (Work_queue.msgs[0]). addr = slave_address;     
         
    (Work_queue.msgs[0]). buf = W_buf;     
         
    memcpy (w_buf + 1, buf, Len);     
    RET = IOCTL (FD, I2C_RDWR, (unsigned long) &work_queue);     
        if (Ret < 0) {printf ("error during I2C_RDWR IOCTL with error code:%d\n", ret);     
        Close (FD);     
        Free (WORK_QUEUE.MSGS);     
    return 0;     
        else {printf ("Write salve:%02x reg:%02x\n", slave_address, reg_address);     
        Close (FD);     
        Free (WORK_QUEUE.MSGS);     
    return Len;     
    int main (int argc, char **argv) {unsigned int fd;     
    unsigned int slave_address, reg_address;     
    unsigned r_w;     
    unsigned w_val;
         
    unsigned char rw_val; if (ARGC < 5) {printf ("Usage:\n%s/dev/i2c-x start_addr reg_addr RW[0|1]     
        [write_val]\n ", argv[0]);     
    return 0;     
         
    FD = open (argv[1], O_RDWR);     
        if (!FD) {printf ("Error on opening" device file%s\n ", argv[1]);     
    return 0;     
    } sscanf (Argv[2], "%x", &slave_address);     
    SSCANF (Argv[3], "%x", ®_address);     
         
    SSCANF (Argv[4], "%d", &r_w);     
        if (R_w = = 0) {I2c_read_reg (argv[1], &rw_val, slave_address, reg_address, 1);     
    printf ("Read%s-%x reg%x, read value:%x\n", Argv[1], slave_address, reg_address, Rw_val); else {if (ARGC < 6) {printf ("Usage:\n%s/dev/i2c-x start_addr reg_addr r|w[0|1] [writ     
            E_val]\n ", argv[0]);     
        return 0;     
        } sscanf (Argv[5], "%d", &w_val);     
         
        if ((W_val & ~0xff)!= 0) printf ("Error on written value%s\n", argv[5]); Rw_val = (unsigned char) W_val;     
    I2c_write_reg (Argv[1], &rw_val, slave_address, reg_address, 1);     
return 0; }

In android/external/new I2c-util directory, the above source code into ANDROID/EXTERNAL/I2C-UTIL/I2C-UTIL.C, write the corresponding android.mk:

Local_path: = $ (call My-dir)     
include $ (clear_vars)

local_module_tags: = Optional local_module
         
: = i2c-util< C4/>local_src_files + +
    i2c-util.c \
         
include $ (build_executable)

Once Android is compiled, the above tools are located in the/system/bin directory. Use it on a circuit board:

/#  I2c-rw/dev/i2c-2 0x38 0x1 0   
read salve:38 reg:01 value:12   
/#        
/#  i2c-rw/dev/i2c-2 0x38 0x2 0   
Read salve:38 reg:02 value:81

This article is from the "Song Baohua blog" blog, please be sure to keep this source http://21cnbao.blog.51cto.com/109393/976137