zynq-7000 获取CPU片内温度

<*> Xilinx XADC driver

  amba: amba {
                u-boot,dm-pre-reloc;
                compatible = "simple-bus";
                #address-cells = <1>;
                #size-cells = <1>;
                interrupt-parent = <&intc>;
                ranges;

                adc: adc@f8007100 {
                        compatible = "xlnx,zynq-xadc-1.00.a";
                        reg = <0xf8007100 0x20>;
                        interrupts = <0 7 4>;
                        interrupt-parent = <&intc>;
                        clocks = <&clkc 12>;
                };

#include <stdio.h>
#include <string.h>
#include <errno.h>
#include <unistd.h>
#include <dirent.h>
#include <stdlib.h>
#include <sys/ioctl.h>
#include <fcntl.h>
#include <ctype.h>
#include <pthread.h>
#include <assert.h>
#include <termios.h> 
#include <signal.h>
/**IIO获取温度原始值文件**/
#define SYS_PATH_TEMP_IIO_VALUE    "/sys/bus/iio/devices/iio:device0/in_temp0_raw"
static const int multiplier = 1 << 12; //4096
 
int main(int argc, char *argv[])
{
    FILE *stream;
    float val;
    float temp_value;
     unsigned  char buf[20];
       if ((stream = fopen(SYS_PATH_TEMP_IIO_VALUE, "w+"))== NULL)
       {
          fprintf(stderr,"Cannot open output file.\n");
            return 1;
        }
     fseek(stream, SEEK_SET, 0);
        fread(buf, sizeof(char), sizeof(buf), stream);
     val=atof(buf);
     temp_value=((val * 503.975)/multiplier )-273.15;
     printf("The cpu temp is %.2f\r\n",temp_value);
     fclose(stream); 
     return 0;
}

root:~/test/temp# ./temp 
The cpu temp is 74.07