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iopower_getattr()

Get the power attributes of a power managed device

Synopsis:

#include <sys/pm.h>
int iopower_getattr(int filedes, pm_power_attr_t *attr);

Arguments:

filedes: A file descriptor to the device special file.
attr: Pointer to where the power attributes are returned.

Description:

The iopower_getattr() function replaces pm_get_power() that has been deprecated.

The iopower_getattr() gets the current power attributes of a power managed device.

The current power mode is returned in attr->cur_mode.

If the device is in the process of changing power modes, the new mode will be returned in attr->new_mode.

The number of power modes supported by the device is returned in attr->num_modes. This value can be supplied to iopower_getmodes() or iopower_modeattr() to retrieve the full list of supported modes.

Returns:

0: Success.
-1: An error has occurred (errno is set).

Errors:

EBADF: filedes is not a valid file descriptor.
EFAULT: A fault occurred accesing modes.
ENOSYS: The device specified by filedes doesn't implement power management.

Examples:

#include <sys/pm.h>
#include <fcntl.h>
#include <stdio.h>
#include <stdlib.h>

int main(void)
{
   int     fd;
   pm_power_attr_t attr;

   fd = open("/dev/device", O_RDONLY);
   if (fd == -1) {
      perror("open");
      return EXIT_FAILURE;
    }
    if (iopower_getattr(fd, &attr) == -1) {
       perror("iopower_getattr");
       return EXIT_FAILURE;
    }
    printf("Device supports %d modes\n", attr.num_modes);
    printf("cur_mode = 0x%x\n", attr.cur_mode);
    printf("new_mode = 0x%x\n", attr.new_mode);
    return EXIT_SUCCESS;
}

Classification:

Neutrino

Safety:
Cancellation point	Yes
Interrupt handler	No
Signal handler	Yes
Thread	Yes