Re: How access spi device via spi driver?

["Ren Jeffery" <finderren@xxxxxxxxx>]

Hi ,
>your question is how can I access a device that dose not appear on /dev
directory.
>the answer is "mknod" command.

>reference:
>153 char    SPI Bus Interface (sometimes referred to as MicroWire)
>          0 = /dev/spi0        First SPI device on the bus
>          1 = /dev/spi1        Second SPI device on the bus
>            ...
>         15 = /dev/spi15    Sixteenth SPI device on the bus


Thanks for your reply.
I have added following into /etc/init.d/rcS

mknod /dev/spi0 c 153 0

And write some test code(See the end of this mail.)
But, I fail to open this device,  "No such device or address"
I'm trapped again. What's wrong with it???

>>
[root@arm-linux /home]# ls -al /dev/spi0
crw-r--r--    1 root     root     153,   0 Jan  1  1970 /dev/spi0
[root@utu-linux /home]# ./spi_test
: No such device or address

>>MY TEST CODE:

#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <sys/ioctl.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <errno.h>

int main(void)
{
 int spi_fd;

 spi_fd = open("/dev/spi0", O_RDWR);
 if (spi_fd < 0)
 {
  perror("cann't open device /dev/spi0\n");
  exit(1);
 }

 for(;;)
 {
  char str[20];
  scanf("%s",str);
  if ('1' == str[0])
   break;

  int ret = write(spi_fd, &str, sizeof str);
  if (ret <= 0)
  {
   printf("file operation error.\n");
  }

  printf("You write to spi device: %s\n", str);
 }
 close(spi_fd);
 return 0;
}
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