Re: [Xen-devel] [PATCH v2 03/20] piix4: Add a i8259 Interrupt Controller as specified in datasheet

[Philippe Mathieu-Daudé <philmd@xxxxxxxxxx>]

On 10/22/19 10:48 AM, Esteban Bosse wrote:
> El vie, 18-10-2019 a las 15:47 +0200, Philippe Mathieu-Daudé escribió:
> > From: Hervé Poussineau <hpoussin@xxxxxxxxxxx>
> >
> > Add ISA irqs as piix4 gpio in, and CPU interrupt request as piix4
> > gpio out.
> > Remove i8259 instanciated in malta board, to not have it twice.
> >
> > We can also remove the now unused piix4_init() function.
> >
> > Acked-by: Michael S. Tsirkin <mst@xxxxxxxxxx>
> > Acked-by: Paolo Bonzini <pbonzini@xxxxxxxxxx>
> > Signed-off-by: Hervé Poussineau <hpoussin@xxxxxxxxxxx>
> > Message-Id: <20171216090228.28505-8-hpoussin@xxxxxxxxxxx>
> > Reviewed-by: Aleksandar Markovic <amarkovic@xxxxxxxxxxxx>
> > [PMD: rebased, updated includes, use ISA_NUM_IRQS in for loop]
> > Signed-off-by: Philippe Mathieu-Daudé <philmd@xxxxxxxxxx>
> > ---
> >   hw/isa/piix4.c       | 43 ++++++++++++++++++++++++++++++++--------
> > ---
> >   hw/mips/mips_malta.c | 32 +++++++++++++-------------------
> >   include/hw/i386/pc.h |  1 -
> >   3 files changed, 45 insertions(+), 31 deletions(-)
> >
> > diff --git a/hw/isa/piix4.c b/hw/isa/piix4.c
> > index d0b18e0586..9c37c85ae2 100644
> > --- a/hw/isa/piix4.c
> > +++ b/hw/isa/piix4.c
> > @@ -24,6 +24,7 @@
> >    */
> >   
> >   #include "qemu/osdep.h"
> > +#include "hw/irq.h"
> >   #include "hw/i386/pc.h"
> >   #include "hw/pci/pci.h"
> >   #include "hw/isa/isa.h"
> > @@ -36,6 +37,8 @@ PCIDevice *piix4_dev;
> >   
> >   typedef struct PIIX4State {
> >       PCIDevice dev;
> > +    qemu_irq cpu_intr;
> > +    qemu_irq *isa;
> >   
> >       /* Reset Control Register */
> >       MemoryRegion rcr_mem;
> > @@ -94,6 +97,18 @@ static const VMStateDescription vmstate_piix4 = {
> >       }
> >   };
> >   
> > +static void piix4_request_i8259_irq(void *opaque, int irq, int
> > level)
> > +{
> > +    PIIX4State *s = opaque;
> > +    qemu_set_irq(s->cpu_intr, level);
> > +}
> I would like to understand why in `PIIX4State *s = opaque;` its not
> necessary a cast or a object macro magic.
> Something like:
> PIIX4State *s = (PIIX4State*)opaque;
> PIIX4State *s = PIIX4STATE(opaque);
I guess you mean:

#define PIIX4_PCI_DEVICE(obj) \
    OBJECT_CHECK(PIIX4State, (obj), TYPE_PIIX4_PCI_DEVICE)

IIUC the OBJECT_CHECK(STATE, OBJ, TYPE) macro verify the QEMU Object
OBJ is of the correct type TYPE, then cast it as a pointer to STATE.
This has some runtime cost.

This is useful when you deal with some child Object which is not TYPE
but inheritate TYPE from a parent, or if the object is an abstract
parent and you want to use its children TYPE implementations.

In piix4_realize(), the function piix4_request_i8259_irq() is registered 
by qemu_allocate_irqs() as a handler with 's' as opaque pointer, and we
already know 's' is of type PIIX4State, so using OBJECT_CHECK() is not
necessary.

> > +
> > +static void piix4_set_i8259_irq(void *opaque, int irq, int level)
> > +{
> > +    PIIX4State *s = opaque;
> > +    qemu_set_irq(s->isa[irq], level);
> > +}
> > +
> >   static void piix4_rcr_write(void *opaque, hwaddr addr, uint64_t val,
> >                               unsigned int len)
> >   {
> > @@ -127,29 +142,35 @@ static const MemoryRegionOps piix4_rcr_ops = {
> >   static void piix4_realize(PCIDevice *dev, Error **errp)
> >   {
> >       PIIX4State *s = PIIX4_PCI_DEVICE(dev);
> > +    ISABus *isa_bus;
> > +    qemu_irq *i8259_out_irq;
> >   
> > -    if (!isa_bus_new(DEVICE(dev), pci_address_space(dev),
> > -                     pci_address_space_io(dev), errp)) {
> > +    isa_bus = isa_bus_new(DEVICE(dev), pci_address_space(dev),
> > +                          pci_address_space_io(dev), errp);
> > +    if (!isa_bus) {
> >           return;
> >       }
> >   
> > +    qdev_init_gpio_in_named(DEVICE(dev), piix4_set_i8259_irq,
> > +                            "isa", ISA_NUM_IRQS);
> > +    qdev_init_gpio_out_named(DEVICE(dev), &s->cpu_intr,
> > +                             "intr", 1);
> > +
> >       memory_region_init_io(&s->rcr_mem, OBJECT(dev), &piix4_rcr_ops,
> > s,
> >                             "reset-control", 1);
> >       memory_region_add_subregion_overlap(pci_address_space_io(dev),
> > 0xcf9,
> >                                           &s->rcr_mem, 1);
> >   
> > +    /* initialize i8259 pic */
> > +    i8259_out_irq = qemu_allocate_irqs(piix4_request_i8259_irq, s,
> > 1);
> > +    s->isa = i8259_init(isa_bus, *i8259_out_irq);
> > +
> > +    /* initialize ISA irqs */
> > +    isa_bus_irqs(isa_bus, s->isa);
> > +
> >       piix4_dev = dev;
> >   }
> >   
> > -int piix4_init(PCIBus *bus, ISABus **isa_bus, int devfn)
> > -{
> > -    PCIDevice *d;
> > -
> > -    d = pci_create_simple_multifunction(bus, devfn, true, "PIIX4");
> > -    *isa_bus = ISA_BUS(qdev_get_child_bus(DEVICE(d), "isa.0"));
> > -    return d->devfn;
> > -}
> > -
> >   static void piix4_class_init(ObjectClass *klass, void *data)
> >   {
> >       DeviceClass *dc = DEVICE_CLASS(klass);
> > diff --git a/hw/mips/mips_malta.c b/hw/mips/mips_malta.c
> > index 4d9c64b36a..7d25ab6c23 100644
> > --- a/hw/mips/mips_malta.c
> > +++ b/hw/mips/mips_malta.c
> > @@ -97,7 +97,7 @@ typedef struct {
> >       SysBusDevice parent_obj;
> >   
> >       MIPSCPSState cps;
> > -    qemu_irq *i8259;
> > +    qemu_irq i8259[16];
> >   } MaltaState;
> >   
> >   static ISADevice *pit;
> > @@ -1235,8 +1235,8 @@ void mips_malta_init(MachineState *machine)
> >       int64_t kernel_entry, bootloader_run_addr;
> >       PCIBus *pci_bus;
> >       ISABus *isa_bus;
> > -    qemu_irq *isa_irq;
> >       qemu_irq cbus_irq, i8259_irq;
> > +    PCIDevice *pci;
> >       int piix4_devfn;
> >       I2CBus *smbus;
> >       DriveInfo *dinfo;
> > @@ -1407,30 +1407,24 @@ void mips_malta_init(MachineState *machine)
> >       /* Board ID = 0x420 (Malta Board with CoreLV) */
> >       stl_p(memory_region_get_ram_ptr(bios_copy) + 0x10, 0x00000420);
> >   
> > -    /*
> > -     * We have a circular dependency problem: pci_bus depends on
> > isa_irq,
> > -     * isa_irq is provided by i8259, i8259 depends on ISA, ISA
> > depends
> > -     * on piix4, and piix4 depends on pci_bus.  To stop the cycle we
> > have
> > -     * qemu_irq_proxy() adds an extra bit of indirection, allowing
> > us
> > -     * to resolve the isa_irq -> i8259 dependency after i8259 is
> > initialized.
> > -     */
> > -    isa_irq = qemu_irq_proxy(&s->i8259, 16);
> > -
> >       /* Northbridge */
> > -    pci_bus = gt64120_register(isa_irq);
> > +    pci_bus = gt64120_register(s->i8259);
> >   
> >       /* Southbridge */
> >       ide_drive_get(hd, ARRAY_SIZE(hd));
> >   
> > -    piix4_devfn = piix4_init(pci_bus, &isa_bus, 80);
> > +    pci = pci_create_simple_multifunction(pci_bus, PCI_DEVFN(10, 0),
> > +                                          true, "PIIX4");
> > +    dev = DEVICE(pci);
> > +    isa_bus = ISA_BUS(qdev_get_child_bus(dev, "isa.0"));
> > +    piix4_devfn = pci->devfn;
> >   
> > -    /*
> > -     * Interrupt controller
> > -     * The 8259 is attached to the MIPS CPU INT0 pin, ie interrupt 2
> > -     */
> > -    s->i8259 = i8259_init(isa_bus, i8259_irq);
> > +    /* Interrupt controller */
> > +    qdev_connect_gpio_out_named(dev, "intr", 0, i8259_irq);
> > +    for (int i = 0; i < ISA_NUM_IRQS; i++) {
> > +        s->i8259[i] = qdev_get_gpio_in_named(dev, "isa", i);
> > +    }
> >   
> > -    isa_bus_irqs(isa_bus, s->i8259);
> >       pci_piix4_ide_init(pci_bus, hd, piix4_devfn + 1);
> >       pci_create_simple(pci_bus, piix4_devfn + 2, "piix4-usb-uhci");
> >       smbus = piix4_pm_init(pci_bus, piix4_devfn + 3, 0x1100,
> > diff --git a/include/hw/i386/pc.h b/include/hw/i386/pc.h
> > index 37bfd95113..374f3e8835 100644
> > --- a/include/hw/i386/pc.h
> > +++ b/include/hw/i386/pc.h
> > @@ -286,7 +286,6 @@ PCIBus *i440fx_init(const char *host_type, const
> > char *pci_type,
> >   PCIBus *find_i440fx(void);
> >   /* piix4.c */
> >   extern PCIDevice *piix4_dev;
> > -int piix4_init(PCIBus *bus, ISABus **isa_bus, int devfn);
> >   
> >   /* pc_sysfw.c */
> >   void pc_system_flash_create(PCMachineState *pcms);
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