Example of Device Driver

Example of Device Driver

The code in /usr/react/src/examples/driver contains a skeletal test-bed for a kernel-level device driver that interacts with the Frame Scheduler. Most of the driver functions consist of minimal or empty stubs. However, the ioctl() entry point to the driver (see the ioctl(2) reference page) simulates a hardware interrupt and calls the Frame Scheduler entry point, frs_handle_driverintr() (see "Generating Interrupts"). This allows you to test the driver. Calling its ioctl() entry is equivalent to using frs_usrintr() (see "The Frame Scheduler API").

The code in /usr/react/src/examples/dintr contains a variant of the simple example that uses a device driver as the time base. The program dintr/sendintr.c opens the driver, calls ioctl() to send one time-base interrupt, and closes the driver. (It could easily be extended to send a specified number of interrupts, or to send an interrupt each time the return key is pressed.)