On Thu, 23 Feb 2006, Kumar Gala wrote:
> >> Yes, the FPGA is a pci device.
> >>
> >> Not sure I follow exactly what you mean by the fact that platform
> >> devices dont know about mmio regions. They know about struct
> >> resource and iomem_resource & ioport_resource.
> >
> > Yes, as they have no "bus" to attach too. That's why they are there,
> > they are for devices with no bus, but are merely "raw" memory mapped
> > devices.
>
> I'm not sure I follow this. How is PCI different? How would "kumar"
> bus be different?
>
> >> I think I might be missing something fundamental here. In
> >> implementing my own bus_type, I'll end up introducing my own struct
> >> foobar_device which looked pretty much like struct platform_device.
> >> Then I'll need a set of functions to assign resources, etc.
> >>
> >> I got no issue implementing my own bus_type, but I clearly feel like
> >> I'm missing something here (just not sure what it is :)
> >
> > I guess I look at your FPGA as a PCI "bridge" chip, that bridges
> > between
> > the PCI bus, and your "kumar" bus (for lack of a better name). Your
> > devices hang off of that bus, which is attached to the FPGA, which is
> > attached to the pci bridge, and so on. If you use the platform
> > bus, you
> > break that link.
> >
> > Does that make sense?
>
> This makes sense, but you seem to be talking about hierarchy more the
> functionality. I agree in your description of hierarchy.
>
> I was looking at it from a functional point of view, maybe more from
> the device view then from the bus. I need a struct device type that
> contains resources, a name, an id. I'll do matching based on name.
> From a functional point of view platform does all this.
>
> Based on your description would you say that a platform_device's
> parent device should always be platform_bus? [I'm getting at the fact
> that we allow pdev->dev.parent to be set by the caller of
> platform_device_add].
>
> Hmm, as I think about this further, I think that its more coincidence
> that the functionality for the "kumar" bus is equivalent to that of
> the "platform" bus.
>
What about a new bus_type that uses all the sematics of the platform_bus.
Doing someting like the following which would allow the caller to specify
their own bus_type.
I'm just trying to avoid duplicating alot of code that already exists in
base/platform.c
- kumar
diff --git a/drivers/base/platform.c b/drivers/base/platform.c
index 461554a..fb320e9 100644
--- a/drivers/base/platform.c
+++ b/drivers/base/platform.c
@@ -242,7 +242,8 @@ int platform_device_add(struct platform_
if (!pdev->dev.parent)
pdev->dev.parent = &platform_bus;
- pdev->dev.bus = &platform_bus_type;
+ if (!pdev->dev.bus)
+ pdev->dev.bus = &platform_bus_type;
if (pdev->id != -1)
snprintf(pdev->dev.bus_id, BUS_ID_SIZE, "%s.%u", pdev->name, pdev->id);
@@ -426,7 +427,8 @@ static int platform_drv_resume(struct de
*/
int platform_driver_register(struct platform_driver *drv)
{
- drv->driver.bus = &platform_bus_type;
+ if (!drv->driver.bus)
+ drv->driver.bus = &platform_bus_type;
if (drv->probe)
drv->driver.probe = platform_drv_probe;
if (drv->remove)
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to [email protected]
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
[Index of Archives]
[Kernel Newbies]
[Netfilter]
[Bugtraq]
[Photo]
[Stuff]
[Gimp]
[Yosemite News]
[MIPS Linux]
[ARM Linux]
[Linux Security]
[Linux RAID]
[Video 4 Linux]
[Linux for the blind]
[Linux Resources]
