Re: [Qemu-devel] [PATCH 1/5] i8259: qdev-ify creation

[Alexander Graf <agraf@suse.de>]

On 12.01.2012, at 09:09, Jan Kiszka wrote:

> On 2012-01-12 09:05, Alexander Graf wrote:
>> 
>> On 12.01.2012, at 09:00, Jan Kiszka wrote:
>> 
>>> On 2012-01-12 08:58, Alexander Graf wrote:
>>>> 
>>>> On 12.01.2012, at 08:35, Jan Kiszka wrote:
>>>> 
>>>>> On 2012-01-12 01:04, Andreas Färber wrote:
>>>>>> Alex,
>>>>>> 
>>>>>> I have this in my mailbox, but I'm still waiting for an SoB. Hervé?
>>>>>> 
>>>>>> Regards,
>>>>>> Andreas
>>>>>> 
>>>>>> -------- Original-Nachricht --------
>>>>>> Betreff: [PATCH 1/5] i8259: qdev-ify creation
>>>>>> Datum: Sun, 26 Jun 2011 14:47:09 +0200
>>>>>> Von: Hervé Poussineau <hpoussin@reactos.org>
>>>>>> An: andreas.faerber@web.de
>>>>>> Kopie (CC): Hervé Poussineau <hpoussin@reactos.org>
>>>>>> 
>>>>>> ---
>>>>>> hw/i8259.c |   53 +++++++++++++++++++++++++++++++++++++++++++++++++----
>>>>>> 1 files changed, 49 insertions(+), 4 deletions(-)
>>>>>> 
>>>>>> diff --git a/hw/i8259.c b/hw/i8259.c
>>>>>> index 84d330d..59e8bd6 100644
>>>>>> --- a/hw/i8259.c
>>>>>> +++ b/hw/i8259.c
>>>>>> @@ -26,6 +26,7 @@
>>>>>> #include "isa.h"
>>>>>> #include "monitor.h"
>>>>>> #include "qemu-timer.h"
>>>>>> +#include "sysbus.h"
>>>>>> 
>>>>>> /* debug PIC */
>>>>>> //#define DEBUG_PIC
>>>>>> @@ -524,16 +525,60 @@ void irq_info(Monitor *mon)
>>>>>> 
>>>>>> qemu_irq *i8259_init(qemu_irq parent_irq)
>>>>>> {
>>>>>> -    PicState2 *s;
>>>>>> +    DeviceState *dev;
>>>>>> +    dev = qdev_create(NULL, "i8259");
>>>>>> +    qdev_init_nofail(dev);
>>>>>> +    qdev_connect_gpio_out(dev, 0, parent_irq);
>>>>>> +
>>>>>> +    return dev->gpio_in;
>>>>>> +}
>>>>>> +
>>>>>> +typedef struct SysBusPicState2 {
>>>>>> +    SysBusDevice busdev;
>>>>>> +    PicState2 state;
>>>>>> +} SysBusPicState2;
>>>>>> +
>>>>>> +static void i8259_set_irq_sysbus(void *opaque, int line, int level)
>>>>>> +{
>>>>>> +    SysBusPicState2 *sysbus = opaque;
>>>>>> +    PicState2 *s = &sysbus->state;
>>>>>> +    i8259_set_irq(s, line, level);
>>>>>> +}
>>>>>> +
>>>>>> +static int i8259_sysbus_init(SysBusDevice *dev)
>>>>>> +{
>>>>>> +    SysBusPicState2 *sysbus = FROM_SYSBUS(SysBusPicState2, dev);
>>>>>> +    PicState2 *s = &sysbus->state;
>>>>>> +
>>>>>> +    if (isa_pic) {
>>>>>> +        return 1;
>>>>>> +    }
>>>>>> 
>>>>>> -    s = qemu_mallocz(sizeof(PicState2));
>>>>>>   pic_init1(0x20, 0x4d0, &s->pics[0]);
>>>>>>   pic_init1(0xa0, 0x4d1, &s->pics[1]);
>>>>>>   s->pics[0].elcr_mask = 0xf8;
>>>>>>   s->pics[1].elcr_mask = 0xde;
>>>>>> -    s->parent_irq = parent_irq;
>>>>>>   s->pics[0].pics_state = s;
>>>>>>   s->pics[1].pics_state = s;
>>>>>>   isa_pic = s;
>>>>>> -    return qemu_allocate_irqs(i8259_set_irq, s, 16);
>>>>>> +
>>>>>> +    qdev_init_gpio_in(&dev->qdev, i8259_set_irq_sysbus, 16);
>>>>>> +    qdev_init_gpio_out(&dev->qdev, &s->parent_irq, 1);
>>>>>> +    return 0;
>>>>>> +}
>>>>>> +
>>>>>> +static SysBusDeviceInfo i8259_sysbus_info = {
>>>>>> +    .qdev.name = "i8259",
>>>>>> +    .qdev.size = sizeof(SysBusPicState2),
>>>>>> +    .init = i8259_sysbus_init,
>>>>>> +    .qdev.props = (Property[]) {
>>>>>> +        DEFINE_PROP_END_OF_LIST()
>>>>>> +    },
>>>>>> +};
>>>>>> +
>>>>>> +static void i8259_register_devices(void)
>>>>>> +{
>>>>>> +   sysbus_register_withprop(&i8259_sysbus_info);
>>>>>> }
>>>>>> +
>>>>>> +device_init(i8259_register_devices)
>>>>> 
>>>>> This is obsolete. The i8259 has been significantly refactored (into two
>>>>> ISA devices) and qdev'ified some moons ago.
>>>> 
>>>> The reason we were discussing this was a circular dependency on PREP.
>>>> 
>>>> The PIC is sitting on the ISA bus.
>>>> The ISA bus is behind a PCI-ISA bridge
>>>> the PCI-ISA bridge is behind a PCI host controller
>>>> the PCI host controller needs interrupt lines in its initialization which are attached to the PIC
>>>> 
>>>> Any good ideas on how to resolve this? :)
>>> 
>>> As we do this always: Split up initialization and IRQ line wiring.
>> 
>> Well, yes, the theory is obvious. How would this look like in practice? To create a PIC device I need a bus:
>> 
>>    dev = isa_create(bus, "isa-i8259");
>> 
>> But to create the bus, I need an interrupt line, which I only get after I created the PIC device.
> 
> ISA bus creation and IRQ assignment are split up IIRC.

So you're saying we should do the same for PCI?
To create an ISA bus that sits behind a PCI device I first need to create a PCI bus which is exposed by the host bridge which then again needs interrupt lines.

I'm still puzzled how we would pass on irq lines then. I mean setting them after init means that during init we can't instantiate other devices that we can wire up to anything, right?

Alex