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mraa: add internal mraa_find_i2c_bus function

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Signed-off-by: Brendan Le Foll <brendan.le.foll@intel.com>
This commit is contained in:
Brendan Le Foll
2015-07-10 17:52:50 +01:00
parent f5d6a6dc18
commit df0dbb0c73
4 changed files with 123 additions and 81 deletions
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86
src/mraa.c
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@@ -23,13 +23,23 @@
* WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
*/
#define _GNU_SOURCE
#if !defined(_XOPEN_SOURCE) || _XOPEN_SOURCE < 600
#define _XOPEN_SOURCE 600 /* Get nftw() and S_IFSOCK declarations */
#endif
#include <stddef.h>
#include <stdlib.h>
#include <sched.h>
#include <string.h>
#include <pwd.h>
#include <glob.h>
#include <ftw.h>
#include <dirent.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <string.h>
#include <stdio.h>
#include "mraa_internal.h"
#include "gpio.h"
@@ -426,3 +436,77 @@ mraa_link_targets(const char* filename, const char* targetname)
return 0;
}
}
static int num_i2c_devices = 0;
static int
mraa_count_files(const char* path, const struct stat* sb, int flag, struct FTW* ftwb)
{
switch (sb->st_mode & S_IFMT) {
case S_IFLNK:
num_i2c_devices++;
break;
}
return 0;
}
int
mraa_find_i2c_bus(const char* devname, int startfrom)
{
char path[64], value[64];
int fd;
int i = startfrom;
int ret = -1;
// because feeding mraa_find_i2c_bus result back into the function is
// useful treat -1 as 0
if (startfrom < 0) {
startfrom = 0;
}
// find how many i2c buses we have if we haven't already
if (num_i2c_devices == 0) {
if (nftw("/sys/class/i2c-dev/", &mraa_count_files, 20, FTW_PHYS) == -1) {
return -1;
}
}
// i2c devices are numbered numerically so 0 must exist otherwise there is
// no i2c-dev loaded
if (mraa_file_exist("/sys/class/i2c-dev/i2c-0")) {
for (i; i < num_i2c_devices; i++) {
off_t size, err;
snprintf(path, 64, "/sys/class/i2c-dev/i2c-%u/name", i);
fd = open(path, O_RDONLY);
if (fd < 0) {
break;
}
size = lseek(fd, 0, SEEK_END);
if (size < 0) {
syslog(LOG_WARNING, "mraa: failed to seek i2c filename file");
close(fd);
break;
}
err = lseek(fd, 0, SEEK_SET);
if (err < 0) {
syslog(LOG_WARNING, "mraa: failed to seek i2c filename file");
close(fd);
break;
}
ssize_t r = read(fd, value, size);
if (r > 0) {
if (strcasestr(value, devname) != NULL) {
close(fd);
return i;
}
} else {
syslog(LOG_ERR, "mraa: sysfs i2cdev failed");
}
close(fd);
}
} else {
syslog(LOG_WARNING, "mraa: no i2c-dev detected, load i2c-dev");
}
return ret;
}