Writing device drivers: How to access a specific memory area?
Hello all, I am writing a driver which needs to access memory at a specific location. The location depends on what the BIOS has configured into the host bridge. For example, my current machine uses an Intel 975X chipset and the memory location I am interested in has been set to 0xFED14000 and is 16KB in size (this is MCHBAR of the 975X memory hub). I have no idea how to access this space from my driver. I have played around with bus_alloc_resource() but this only gives me back NULL. However, a devinfo -r gives me: nexus0 npx0 acpi0 Interrupt request lines: 9 I/O ports: 0x10-0x1f ... 0x800-0x87f I/O memory addresses: 0x0-0x9 0xc-0xd 0xe-0xf 0x10-0x7fff 0xf000-0xf3ff 0xfec0-0xfec00fff 0xfed13000-0xfed19fff <--- 0xfed1c000-0xfed1 0xfed2-0xfed3 0xfed5-0xfed8 0xfee0-0xfee00fff 0xffb0-0xffbf 0xfff0-0x cpu0 ... The line marked with <--- shows the range which includes the location I am interested in. It is probably assigned to the acpi0 device. How do I proceed from this? Do I have to hack around in the ACPI-Code? I don't hope so ;-) I only need access to this memory location during the probe of my driver to read some configuration data. I do not need to access it later anymore... Thanks a lot for any hints, -Andre ___ freebsd-hackers@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-hackers To unsubscribe, send any mail to "freebsd-hackers-unsubscr...@freebsd.org"
Re: Writing device drivers: How to access a specific memory area?
On 25 Dec 2008, at 09:53, Andre Albsmeier wrote:
Hello all,
I am writing a driver which needs to access memory at a
specific location. The location depends on what the BIOS
has configured into the host bridge. For example, my
current machine uses an Intel 975X chipset and the memory
location I am interested in has been set to 0xFED14000 and
is 16KB in size (this is MCHBAR of the 975X memory hub).
You probably just need to do something like:
rid = PCI_BAR(number);
res = bus_alloc_resource_any(dev, SYS_RES_MEMORY, &rid, RF_ACTIVE);
And then,
bus_read_4(res, offset from specified PCI BAR);
I have no idea how to access this space from my driver.
I have played around with bus_alloc_resource() but this
only gives me back NULL.
However, a devinfo -r gives me:
nexus0
npx0
acpi0
Interrupt request lines:
9
I/O ports:
0x10-0x1f
...
0x800-0x87f
I/O memory addresses:
0x0-0x9
0xc-0xd
0xe-0xf
0x10-0x7fff
0xf000-0xf3ff
0xfec0-0xfec00fff
0xfed13000-0xfed19fff <---
0xfed1c000-0xfed1
0xfed2-0xfed3
0xfed5-0xfed8
0xfee0-0xfee00fff
0xffb0-0xffbf
0xfff0-0x
cpu0
...
The line marked with <--- shows the range which includes
the location I am interested in. It is probably assigned
to the acpi0 device.
How do I proceed from this? Do I have to hack around in
the ACPI-Code? I don't hope so ;-)
You'll probably need to create a fake ACPI child driver to access it.
Create your identify routine with something like:
static void mydriver_identify(driver_t *driver, device_t parent)
{
if (device_find_child(parent, "mydriver", -1) == NULL &&
mydriver_match(parent))
device_add_child(parent, "mydriver", -1);
}
mydriver_match() should check if you were given the acpi0 device.
I only need access to this memory location during the
probe of my driver to read some configuration data.
Is this pci configuration space ? If so, pci_read_config (man 9 pci)
should be just what you need.
Regards,
--
Rui Paulo
___
freebsd-hackers@freebsd.org mailing list
http://lists.freebsd.org/mailman/listinfo/freebsd-hackers
To unsubscribe, send any mail to "freebsd-hackers-unsubscr...@freebsd.org"
Re: Writing device drivers: How to access a specific memory area?
On Thu, 25-Dec-2008 at 13:57:00 +, Rui Paulo wrote:
>
> On 25 Dec 2008, at 09:53, Andre Albsmeier wrote:
>
> > Hello all,
> >
> > I am writing a driver which needs to access memory at a
> > specific location. The location depends on what the BIOS
> > has configured into the host bridge. For example, my
> > current machine uses an Intel 975X chipset and the memory
> > location I am interested in has been set to 0xFED14000 and
> > is 16KB in size (this is MCHBAR of the 975X memory hub).
>
> You probably just need to do something like:
>
> rid = PCI_BAR(number);
> res = bus_alloc_resource_any(dev, SYS_RES_MEMORY, &rid, RF_ACTIVE);
The problem was, that this memory belongs to acpi0
so I couldn't read it from my driver which has no
resources assigned to it. But, I found a way, see below...
>
> And then,
> bus_read_4(res, offset from specified PCI BAR);
>
> >
> >
> > I have no idea how to access this space from my driver.
> > I have played around with bus_alloc_resource() but this
> > only gives me back NULL.
> >
> > However, a devinfo -r gives me:
> >
> > nexus0
> > npx0
> > acpi0
> > Interrupt request lines:
> > 9
> > I/O ports:
> > 0x10-0x1f
> > ...
> > 0x800-0x87f
> > I/O memory addresses:
> > 0x0-0x9
> > 0xc-0xd
> > 0xe-0xf
> > 0x10-0x7fff
> > 0xf000-0xf3ff
> > 0xfec0-0xfec00fff
> > 0xfed13000-0xfed19fff <---
> > 0xfed1c000-0xfed1
> > 0xfed2-0xfed3
> > 0xfed5-0xfed8
> > 0xfee0-0xfee00fff
> > 0xffb0-0xffbf
> > 0xfff0-0x
> >cpu0
> > ...
> >
> > The line marked with <--- shows the range which includes
> > the location I am interested in. It is probably assigned
> > to the acpi0 device.
> >
> > How do I proceed from this? Do I have to hack around in
> > the ACPI-Code? I don't hope so ;-)
>
> You'll probably need to create a fake ACPI child driver to access it.
>
>
> Create your identify routine with something like:
>
> static void mydriver_identify(driver_t *driver, device_t parent)
> {
> if (device_find_child(parent, "mydriver", -1) == NULL &&
> mydriver_match(parent))
> device_add_child(parent, "mydriver", -1);
> }
>
> mydriver_match() should check if you were given the acpi0 device.
Found something easier: I just do a bus_set_resource() followed
by bus_alloc_resource_any(), access my host bridge registers,
and free things with bus_release_resource() followed by
bus_delete_resource().
>
>
> >
> >
> > I only need access to this memory location during the
> > probe of my driver to read some configuration data.
>
> Is this pci configuration space ? If so, pci_read_config (man 9 pci)
Unfortunately not. As I wrote, it is a 16k memory window
where the 975x maps a part of its config registers. The
address of this window can be read by pci_read_config( dev, 0x44, 4 ).
Then you can access the bridge's cXdrcY registers through
this memory window which I needed to determine the
machines RAM layout.
Thanks anyway for your help,
-Andre
___
freebsd-hackers@freebsd.org mailing list
http://lists.freebsd.org/mailman/listinfo/freebsd-hackers
To unsubscribe, send any mail to "freebsd-hackers-unsubscr...@freebsd.org"
