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ELANSC(4) NetBSD/i386 Kernel Interfaces Manual ELANSC(4)
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elansc -- AMD Elan SC520 System Controller driver
elansc* at mainbus? bus ?
gpio* at elansc?
pci* at elansc?
elanpar* at elansc?
elanpex* at elansc?
The 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 fol-
lowing are supported by the elansc driver:
· Watchdog timer. The watchdog timer may be configured for a 1 second,
2 second, 4 second, 8 second, 16 second, or 32 second expiration
· PCI exceptions reporting. The SC520 microcontroller can report
exceptions that occur as it acts as both a PCI bus master and a bus
target. See i386/elanpex(4).
· RAM write-protection. The SC520 microcontroller can designate write-
protected regions of RAM using the Programmable Address Regions reg-
isters. See i386/elanpar(4).
· 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 ``high'' or ``low'' as out-
puts. Pins can be accessed through the gpio(4) framework. The
gpioctl(8) program allows easy manipulation of pins from userland.
· PCI host-bridge optimization. elansc takes advantage of a sus-
pend/resume cycle to tune the PCI host-bridge for higher performance.
gpio(4), i386/elanpar(4), i386/elanpex(4), gpioctl(8), wdogctl(8)
The elansc device first appeared in NetBSD 2.0. PIO function support was
added in OpenBSD 3.6, and subsequently ported to NetBSD 4.0. Support for
PCI exceptions reporting and for RAM write-protection first appeared in
The elansc driver was written by Jason R. Thorpe <thorpej@NetBSD.org>.
Jasper Wallace provided the work-around for a hardware bug related to the
watchdog timer in some steppings of the SC520 CPU. Support for the PIO
function was added to OpenBSD 3.6 by Alexander Yurchenko
<email@example.com> and was ported to NetBSD by Jeff Rizzo
<riz@NetBSD.org>. David Young <dyoung@NetBSD.org> added support for PCI
exceptions reporting and for RAM write-protection using the Programmable
NetBSD 9.99 August 25, 2020 NetBSD 9.99