AMD Elan SC520 System Controller with
watchdog timer and GPIO
elansc* at pci?
gpio* at elansc?
elansc driver supports the system
controller of the AMD Elan SC520 microcontroller. The SC520 consists of an
AMD Am5x86 processor core, integrated PCI host controller, and several
standard on-chip devices, such as NS16550-compatible UARTs, real-time clock,
The Elan SC520 also provides several special on-chip devices. The
following are supported by the
- Watchdog timer. The watchdog timer may be configured for a 1 second, 2 second, 4 second, 8 second, 16 second, or 32 second expiration period.
- Programmable Input/Output. The SC520 microcontroller supports 32 programmable I/O signals (PIOs) that can be used on the system board to monitor signals or control devices that are not handled by the other functions in the SC520 microcontroller. These signals can be programmed to be inputs or to be driven out “high” or “low” as outputs. Pins can be accessed through the gpio(4) framework. The gpioctl(8) program allows easy manipulation of pins from userland.
gpio(4), intro(4), watchdog(4), gpioctl(8), sysctl(8)
Support for the
elansc was added in
OpenBSD 3.3. PIO function support appeared in
elansc driver was written by
Jason R. Thorpe
Jasper Wallace provided the work-around for a
hardware bug related to the watchdog timer in some steppings of the SC520
CPU. Alexander Yurchenko
added support for the PIO function.