Check if the character device's output buffer is full
#include <qvm/cdev.h>
static int cdev_output_full(const struct cdev_state *const cds)
Calling this function makes sense only if you are using the internal buffers (i.e., you specified a non-zero buffer size when calling cdev_setup()).
If the output buffer is full, 1 (one); if the output buffer isn't full, 0 (zero); otherwise, a negative errno value.