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

[Alexander Graf]

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 <address@hidden>
>>>> An: address@hidden
>>>> Kopie (CC): Hervé Poussineau <address@hidden>
>>>> 
>>>> ---
>>>> 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.


Alex