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According to the ACPI spec, the bus number of the child PCI bus of a host

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to PCI bridge can be read be evaluating the _BBN method of the host to PCI
device.  Unfortunately, there appear to be some lazy/ignorant/moronic/
whatever BIOS writers that return 0 for _BBN for all host to PCI bridges in
the system.  On a system with a single host to PCI bridge this is not a
problem as the child bus of that single bridge will be bus 0 anyway.
However, on systems with multiple host to PCI bridges and l/i/m/w BIOS
writers this is a major problem resulting in all but the first host to
PCI bridge failing to attach.  So, this adds a workaround.

If the _BBN of a host to PCI bridge is zero and pcib0 already exists
and is not us, the we use _ADR to look up our PCI function and slot
(we currently assume we are on bus 0) and use that to call
host_pcib_get_busno() to try and extract our bus number from config
registers on the host to PCI bridge device.  If that fails, then we make
an evil assumption that ACPI's _SB_ namespace lays out the host to PCI
bridges in ascending order and use our pcib unit number as our bus
number.

Approved by:	re
This commit is contained in:
John Baldwin 2002-11-22 18:11:13 +00:00
parent b173edafc7
commit 9debb53220
1 changed files with 52 additions and 7 deletions
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59
sys/dev/acpica/acpi_pcib_acpi.c
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@ -132,6 +132,8 @@ acpi_pcib_acpi_attach(device_t dev)
{
struct acpi_hpcib_softc *sc;
ACPI_STATUS status;
uint addr, slot, func, busok;
uint8_t busno;
ACPI_FUNCTION_TRACE((char *)(uintptr_t)__func__);
@ -140,7 +142,7 @@ acpi_pcib_acpi_attach(device_t dev)
sc->ap_handle = acpi_get_handle(dev);
/*
* Get our base bus number by evaluating _BBN. If that doesn't work, try _ADR.
* Get our base bus number by evaluating _BBN.
* If this doesn't work, we assume we're bus number 0.
*
* XXX note that it may also not exist in the case where we are
@ -151,23 +153,66 @@ acpi_pcib_acpi_attach(device_t dev)
* default PCI configuration space handlers can deal with this bus,
* we should attach our own handler.
* XXX invoke _REG on this for the PCI config space address space?
* XXX It seems many BIOS's with multiple Host-PCI bridges do not set
* _BBN correctly. They set _BBN to zero for all bridges. Thus,
* if _BBN is zero and pcib0 already exists, we try to read our
* bus number from the configuration registers at address _ADR.
*/
if (ACPI_FAILURE(status = acpi_EvaluateInteger(sc->ap_handle, "_BBN", &sc->ap_bus))) {
status = acpi_EvaluateInteger(sc->ap_handle, "_BBN", &sc->ap_bus);
if (ACPI_FAILURE(status)) {
if (status != AE_NOT_FOUND) {
device_printf(dev, "could not evaluate _BBN - %s\n", AcpiFormatException(status));
device_printf(dev, "could not evaluate _BBN - %s\n",
AcpiFormatException(status));
return_VALUE(ENXIO);
}
if (ACPI_FAILURE(status = acpi_EvaluateInteger(sc->ap_handle, "_ADR", &sc->ap_bus))) {
} else {
/* if it's not found, assume 0 */
sc->ap_bus = 0;
}
/*
* If the bus is zero and pcib0 already exists, read the bus number
* via PCI config space.
*/
busok = 1;
if (sc->ap_bus == 0 && devclass_get_device(pcib_devclass, 0) != dev) {
status = acpi_EvaluateInteger(sc->ap_handle, "_ADR", &addr);
if (ACPI_FAILURE(status)) {
if (status != AE_NOT_FOUND) {
device_printf(dev, "could not evaluate _ADR - %s\n", AcpiFormatException(status));
device_printf(dev, "could not evaluate _ADR - %s\n",
AcpiFormatException(status));
return_VALUE(ENXIO);
} else {
device_printf(dev, "could not determine config space address\n");
busok = 0;
}
} else {
/* if it's not found, assume 0 */
sc->ap_bus = 0;
/* XXX: We assume bus 0. */
slot = addr >> 16;
func = addr & 0xffff;
if (bootverbose)
device_printf(dev, "reading config registers from 0:%d:%d\n",
slot, func);
if (host_pcib_get_busno(pci_cfgregread, 0, slot, func, &busno) == 0) {
device_printf(dev, "could not read bus number from config space\n");
busok = 0;
} else {
sc->ap_bus = busno;
}
}
}
/*
* If nothing else worked, hope that ACPI at least lays out the
* host-PCI bridges in order and that as a result our unit number
* is actually our bus number. There are several reasons this
* might not be true.
*/
if (busok == 0) {
sc->ap_bus = device_get_unit(dev);
device_printf(dev, "trying bus number %d\n", sc->ap_bus);
}
/*
* Get our segment number by evaluating _SEG
* It's OK for this to not exist.