Elan SC520 System Controller with watchdog timer and GPIO
elansc* at pci?
gpio* at 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, and timers.
The Elan SC520 also provides several special on-chip devices. The following are
supported by the elansc
- Watchdog timer. The watchdog timer may be configured for
a 1 second, 2 second, 4 second, 8 second, 16 second, or 32 second
- 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.
Support for the elansc
was added in
. PIO function support appeared in
driver was written by
Jason R. Thorpe
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.