Re: [Qemu-devel] [Qemu-ppc] [PATCH 27/77] ppc/pnv: Add XSCOM infrastructure

[David Gibson]

On Wed, Nov 11, 2015 at 11:27:40AM +1100, Benjamin Herrenschmidt wrote:
> XSCOM is an interface to a sideband bus provided by the POWER8 chip
> pervasive unit, which gives access to a number of facilities in the
> chip that are needed by the OPAL firmware and to a lesser extent,
> Linux. This is among others how the PCI Host bridges get configured
> at boot or how the LPC bus is accessed.
> 
> This provides a simple bus and device type for devices sitting on
> XSCOM along with some facilities to optionally generate corresponding
> device-tree nodes
> 
> Signed-off-by: Benjamin Herrenschmidt <address@hidden>
> ---
>  hw/ppc/Makefile.objs       |   2 +-
>  hw/ppc/pnv.c               |  11 ++
>  hw/ppc/pnv_xscom.c         | 415 
> +++++++++++++++++++++++++++++++++++++++++++++
>  include/hw/ppc/pnv.h       |   2 +
>  include/hw/ppc/pnv_xscom.h |  73 ++++++++
>  5 files changed, 502 insertions(+), 1 deletion(-)
>  create mode 100644 hw/ppc/pnv_xscom.c
>  create mode 100644 include/hw/ppc/pnv_xscom.h
> 
> diff --git a/hw/ppc/Makefile.objs b/hw/ppc/Makefile.objs
> index cd74c96..2a7dd42 100644
> --- a/hw/ppc/Makefile.objs
> +++ b/hw/ppc/Makefile.objs
> @@ -5,7 +5,7 @@ obj-$(CONFIG_PSERIES) += spapr.o spapr_vio.o spapr_events.o
>  obj-$(CONFIG_PSERIES) += spapr_hcall.o spapr_iommu.o spapr_rtas.o
>  obj-$(CONFIG_PSERIES) += spapr_pci.o spapr_rtc.o spapr_drc.o spapr_rng.o
>  # IBM PowerNV
> -obj-$(CONFIG_POWERNV) += pnv.o
> +obj-$(CONFIG_POWERNV) += pnv.o pnv_xscom.o
>  ifeq ($(CONFIG_PCI)$(CONFIG_PSERIES)$(CONFIG_LINUX), yyy)
>  obj-y += spapr_pci_vfio.o
>  endif
> diff --git a/hw/ppc/pnv.c b/hw/ppc/pnv.c
> index e68c9b1..2eac877 100644
> --- a/hw/ppc/pnv.c
> +++ b/hw/ppc/pnv.c
> @@ -41,6 +41,7 @@
>  #include "hw/ppc/ppc.h"
>  #include "hw/ppc/pnv.h"
>  #include "hw/loader.h"
> +#include "hw/ppc/pnv_xscom.h"
>  
>  #include "exec/address-spaces.h"
>  #include "qemu/config-file.h"
> @@ -310,6 +311,7 @@ static void *powernv_create_fdt(PnvSystem *sys, uint32_t 
> initrd_base, uint32_t i
>      uint32_t end_prop = cpu_to_be32(initrd_base + initrd_size);
>      char *buf;
>      const char plat_compat[] = "qemu,powernv\0ibm,powernv";
> +    unsigned int i;
>  
>      fdt = g_malloc0(FDT_MAX_SIZE);
>      _FDT((fdt_create(fdt, FDT_MAX_SIZE)));
> @@ -367,6 +369,12 @@ static void *powernv_create_fdt(PnvSystem *sys, uint32_t 
> initrd_base, uint32_t i
>      /* Memory */
>      _FDT((powernv_populate_memory(fdt)));
>  
> +    /* For each chip */
> +    for (i = 0; i < sys->num_chips; i++) {
> +        /* Populate XSCOM */
> +        _FDT((xscom_populate_fdt(sys->chips[i].xscom, fdt)));
> +    }
> +
>      /* /hypervisor node */
>      if (kvm_enabled()) {
>          uint8_t hypercall[16];
> @@ -424,6 +432,9 @@ static void pnv_create_chip(PnvSystem *sys, unsigned int 
> chip_no)
>  
>      /* XXX Improve chip numbering to better match HW */
>      chip->chip_id = chip_no;
> +
> +    /* Set up XSCOM bus */
> +    xscom_create(chip);

Hmm.. I'm thinking it probably makes sense to unify the representation
of "chip" and "xscom" since there's a 1:1 correspondance.  To be
QOMishly correct, I think the right way would be a SysBusDevice for
each chip, implementing the xscom MMIOs, then an array of link properties
under the Machine object to find the right scoms by chip id.

>  }
>  
>  static void ppc_powernv_init(MachineState *machine)
> diff --git a/hw/ppc/pnv_xscom.c b/hw/ppc/pnv_xscom.c
> new file mode 100644
> index 0000000..bb35422
> --- /dev/null
> +++ b/hw/ppc/pnv_xscom.c
> @@ -0,0 +1,415 @@
> +
> +/*
> + * QEMU PowerNV XSCOM bus definitions
> + *
> + * Copyright (c) 2010 David Gibson, IBM Corporation <address@hidden>
> + * Based on the s390 virtio bus code:
> + * Copyright (c) 2009 Alexander Graf <address@hidden>
> + *
> + * This library is free software; you can redistribute it and/or
> + * modify it under the terms of the GNU Lesser General Public
> + * License as published by the Free Software Foundation; either
> + * version 2 of the License, or (at your option) any later version.
> + *
> + * This library is distributed in the hope that it will be useful,
> + * but WITHOUT ANY WARRANTY; without even the implied warranty of
> + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
> + * Lesser General Public License for more details.
> + *
> + * You should have received a copy of the GNU Lesser General Public
> + * License along with this library; if not, see 
> <http://www.gnu.org/licenses/>.
> + */
> +
> +/* TODO: Add some infrastructure for "random stuff" and FIRs that
> + * various units might want to deal with without creating actual
> + * XSCOM devices.
> + *
> + * For example, HB LPC XSCOM in the PIBAM
> + */
> +#include "hw/hw.h"
> +#include "sysemu/sysemu.h"
> +#include "hw/boards.h"
> +#include "monitor/monitor.h"
> +#include "hw/loader.h"
> +#include "elf.h"
> +#include "hw/sysbus.h"
> +#include "sysemu/kvm.h"
> +#include "sysemu/device_tree.h"
> +#include "kvm_ppc.h"
> +
> +#include "hw/ppc/pnv_xscom.h"
> +
> +#include <libfdt.h>
> +
> +#define TYPE_XSCOM "xscom"
> +#define XSCOM(obj) OBJECT_CHECK(XScomState, (obj), TYPE_XSCOM)
> +
> +#define XSCOM_SIZE        0x800000000ull
> +#define XSCOM_BASE(chip)  (0x3fc0000000000ull + ((uint64_t)(chip)) * 
> XSCOM_SIZE)
> +
> +//#define TRACE_SCOMS
> +
> +typedef struct XScomState {
> +    /*< private >*/
> +    SysBusDevice parent_obj;
> +    /*< public >*/
> +
> +    MemoryRegion mem;
> +    int32_t chip_id;
> +    XScomBus *bus;
> +} XScomState;
> +
> +static uint32_t xscom_to_pcb_addr(uint64_t addr)
> +{
> +        addr &= (XSCOM_SIZE - 1);
> +        return ((addr >> 4) & ~0xfull) | ((addr >> 3) & 0xf);

Wow, that's a pretty weird address transform.

> +}
> +
> +static void xscom_complete(uint64_t hmer_bits)
> +{
> +    CPUState *cs = current_cpu;
> +    PowerPCCPU *cpu = POWERPC_CPU(cs);
> +    CPUPPCState *env = &cpu->env;
> +
> +    cpu_synchronize_state(cs);
> +    env->spr[SPR_HMER] |= hmer_bits;
> +
> +    /* XXX Need a CPU helper to set HMER, also handle gneeration
> +     * of HMIs

Not sure what you're referring to here.  Nothing more should be needed
to set the HMER - because you've called cpu_synchronize_state() it
will be marked dirty and flushed back to KVM before re-entry.

> +     */
> +}
> +
> +static XScomDevice *xscom_find_target(XScomState *s, uint32_t pcb_addr, 
> uint32_t *range)
> +{
> +    BusChild *bc;
> +
> +    QTAILQ_FOREACH(bc, &s->bus->bus.children, sibling) {
> +        DeviceState *qd = bc->child;
> +        XScomDevice *xd = XSCOM_DEVICE(qd);
> +        unsigned int i;
> +
> +        for (i = 0; i < MAX_XSCOM_RANGES; i++) {
> +            if (xd->ranges[i].addr <= pcb_addr &&
> +                (xd->ranges[i].addr + xd->ranges[i].size) > pcb_addr) {
> +                *range = i;
> +                return xd;
> +            }
> +        }
> +    }

I'm wondering if it makes sense to construct a custom AddressSpace and
use the existing address space lookup logic from exec.c and memory.c
rather than implementing your own.

> +    return NULL;
> +}
> +
> +static bool xscom_dispatch_read(XScomState *s, uint32_t pcb_addr, uint64_t 
> *out_val)
> +{
> +    uint32_t range, offset;
> +    struct XScomDevice *xd = xscom_find_target(s, pcb_addr, &range);
> +    XScomDeviceClass *xc;
> +
> +    if (!xd) {
> +        return false;
> +    }
> +    xc = XSCOM_DEVICE_GET_CLASS(xd);
> +    if (!xc->read) {
> +        return false;
> +    }
> +    offset = pcb_addr - xd->ranges[range].addr;
> +    return xc->read(xd, range, offset, out_val);
> +}
> +
> +static bool xscom_dispatch_write(XScomState *s, uint32_t pcb_addr, uint64_t 
> val)
> +{
> +    uint32_t range, offset;
> +    struct XScomDevice *xd = xscom_find_target(s, pcb_addr, &range);
> +    XScomDeviceClass *xc;
> +
> +    if (!xd) {
> +        return false;
> +    }
> +    xc = XSCOM_DEVICE_GET_CLASS(xd);
> +    if (!xc->write) {
> +        return false;
> +    }
> +    offset = pcb_addr - xd->ranges[range].addr;
> +    return xc->write(xd, range, offset, val);
> +}
> +
> +static uint64_t xscom_read(void *opaque, hwaddr addr, unsigned width)
> +{
> +    XScomState *s = opaque;
> +    uint32_t pcba = xscom_to_pcb_addr(addr);
> +    uint64_t val;
> +
> +    assert(width == 8);
> +
> +#ifdef TRACE_SCOMS
> +    printf("XSCOM_READ(0x%x:0x%x)\n", s->chip_id, pcba);
> +#endif

You should be using the built in trace infrastructure here - it's
really not that much of a pain.  Put
        trace_xscom_read(s->chip_id, pcba)
here, put a suitable format in trace-events, and ./configure
--enable-trace-backends=stderr

> +
> +    /* Handle some SCOMs here before dispatch */
> +    switch(pcba) {
> +    case 0xf000f:
> +        val = 0x221EF04980000000;
> +        break;
> +    case 0x1010c00:     /* PIBAM FIR */
> +    case 0x1010c03:     /* PIBAM FIR MASK */
> +    case 0x2020007:     /* ADU stuff */
> +    case 0x2020009:     /* ADU stuff */
> +    case 0x202000f:     /* ADU stuff */
> +        val = 0;
> +        break;
> +    case 0x2013f00:     /* PBA stuff */
> +    case 0x2013f01:     /* PBA stuff */
> +    case 0x2013f02:     /* PBA stuff */
> +    case 0x2013f03:     /* PBA stuff */
> +    case 0x2013f04:     /* PBA stuff */
> +    case 0x2013f05:     /* PBA stuff */
> +    case 0x2013f06:     /* PBA stuff */
> +    case 0x2013f07:     /* PBA stuff */
> +        val = 0;
> +        break;
> +    default:
> +        if (!xscom_dispatch_read(s, pcba, &val)) {
> +            xscom_complete(HMER_XSCOM_FAIL | HMER_XSCOM_DONE);
> +            return 0;
> +        }
> +    }
> +
> +    xscom_complete(HMER_XSCOM_DONE);
> +    return val;
> +}
> +
> +static void xscom_write(void *opaque, hwaddr addr, uint64_t val,
> +                        unsigned width)
> +{
> +    XScomState *s = opaque;
> +    uint32_t pcba = xscom_to_pcb_addr(addr);
> +
> +    assert(width == 8);
> +
> +#ifdef TRACE_SCOMS
> +    printf("XSCOM_WRITE(0x%x:0x%x, 0x%016llx)\n",
> +           s->chip_id, pcba, (unsigned long long)val);
> +#endif
> +    /* Handle some SCOMs here before dispatch */
> +    switch(pcba) {
> +        /* We ignore writes to these */
> +    case 0xf000f:       /* chip id is RO */
> +    case 0x1010c00:     /* PIBAM FIR */
> +    case 0x1010c01:     /* PIBAM FIR */
> +    case 0x1010c02:     /* PIBAM FIR */
> +    case 0x1010c03:     /* PIBAM FIR MASK */
> +    case 0x1010c04:     /* PIBAM FIR MASK */
> +    case 0x1010c05:     /* PIBAM FIR MASK */
> +    case 0x2020007:     /* ADU stuff */
> +    case 0x2020009:     /* ADU stuff */
> +    case 0x202000f:     /* ADU stuff */
> +        break;
> +    default:
> +        if (!xscom_dispatch_write(s, pcba, val)) {
> +            xscom_complete(HMER_XSCOM_FAIL | HMER_XSCOM_DONE);
> +            return;
> +        }
> +    }
> +
> +    xscom_complete(HMER_XSCOM_DONE);
> +}
> +
> +static const MemoryRegionOps xscom_ops = {
> +    .read = xscom_read,
> +    .write = xscom_write,
> +    .valid.min_access_size = 8,
> +    .valid.max_access_size = 8,
> +    .impl.min_access_size = 8,
> +    .impl.max_access_size = 8,
> +    .endianness = DEVICE_BIG_ENDIAN,
> +};
> +
> +static int xscom_init(SysBusDevice *dev)
> +{
> +    XScomState *s = XSCOM(dev);
> +
> +    s->chip_id = -1;
> +    return 0;
> +}
> +
> +static void xscom_realize(DeviceState *dev, Error **errp)
> +{
> +    SysBusDevice *sbd = SYS_BUS_DEVICE(dev);
> +    XScomState *s = XSCOM(dev);
> +    char *name;
> +
> +    assert(s->chip_id >= 0);

So, this assert could be tripped if the user explicitly instantiated
an xscom device which they probably shouldn't do, but could.  So, it
probably makes sense to use error_setg() here instead of assert().

> +    name = g_strdup_printf("xscom-%x", s->chip_id);
> +    memory_region_init_io(&s->mem, OBJECT(s), &xscom_ops, s, name, 
> XSCOM_SIZE);
> +    sysbus_init_mmio(sbd, &s->mem);
> +    sysbus_mmio_map(sbd, 0, XSCOM_BASE(s->chip_id));
> +}
> +
> +static Property xscom_properties[] = {
> +        DEFINE_PROP_INT32("chip_id", XScomState, chip_id, 0),
> +        DEFINE_PROP_END_OF_LIST(),
> +};
> +
> +static void xscom_class_init(ObjectClass *klass, void *data)
> +{
> +    SysBusDeviceClass *k = SYS_BUS_DEVICE_CLASS(klass);
> +    DeviceClass *dc = DEVICE_CLASS(klass);
> +
> +    dc->props = xscom_properties;
> +    dc->realize = xscom_realize;
> +    k->init = xscom_init;
> +}
> +
> +static const TypeInfo xscom_info = {
> +    .name          = TYPE_XSCOM,
> +    .parent        = TYPE_SYS_BUS_DEVICE,
> +    .instance_size = sizeof(XScomState),
> +    .class_init    = xscom_class_init,
> +};
> +
> +static void xscom_bus_class_init(ObjectClass *klass, void *data)
> +{
> +}
> +
> +static const TypeInfo xscom_bus_info = {
> +    .name = TYPE_XSCOM_BUS,
> +    .parent = TYPE_BUS,
> +    .class_init = xscom_bus_class_init,
> +    .instance_size = sizeof(XScomBus),
> +};
> +
> +void xscom_create(PnvChip *chip)
> +{
> +    DeviceState *dev;
> +    XScomState *xdev;
> +    BusState *qbus;
> +    XScomBus *xb;
> +
> +    dev = qdev_create(NULL, TYPE_XSCOM);
> +    qdev_prop_set_uint32(dev, "chip_id", chip->chip_id);
> +    qdev_init_nofail(dev);
> +
> +    /* Create bus on bridge device */
> +    qbus = qbus_create(TYPE_XSCOM_BUS, dev, "xscom");
> +    xb = DO_UPCAST(XScomBus, bus, qbus);
> +    xb->chip_id = chip->chip_id;
> +    xdev = XSCOM(dev);
> +    xdev->bus = xb;
> +    chip->xscom = xb;

I believe the qbus_create() is usually invoked by the bridge's init
function, rather than externally.

> +}
> +
> +#define _FDT(exp) \
> +    do { \
> +        int ret = (exp);                                           \
> +        if (ret < 0) {                                             \
> +            fprintf(stderr, "qemu: error creating device tree: %s: %s\n", \
> +                    #exp, fdt_strerror(ret));                      \
> +            exit(1);                                               \
> +        }                                                          \
> +    } while (0)
> +
> +
> +int xscom_populate_fdt(XScomBus *xb, void *fdt)
> +{
> +    BusChild *bc;
> +    char *name;
> +    const char compat[] = "ibm,power8-xscom\0ibm,xscom";
> +    uint64_t reg[] = { cpu_to_be64(XSCOM_BASE(xb->chip_id)),
> +                       cpu_to_be64(XSCOM_SIZE) };
> +
> +    name = g_strdup_printf("address@hidden", (unsigned long 
> long)be64_to_cpu(reg[0]));
> +    _FDT((fdt_begin_node(fdt, name)));
> +    g_free(name);
> +    _FDT((fdt_property_cell(fdt, "ibm,chip-id", xb->chip_id)));
> +    _FDT((fdt_property_cell(fdt, "#address-cells", 1)));
> +    _FDT((fdt_property_cell(fdt, "#size-cells", 1)));
> +    _FDT((fdt_property(fdt, "reg", reg, sizeof(reg))));
> +    _FDT((fdt_property(fdt, "compatible", compat, sizeof(compat)))); 
> +    _FDT((fdt_property(fdt, "scom-controller", NULL, 0))); 
> +
> +    QTAILQ_FOREACH(bc, &xb->bus.children, sibling) {
> +        DeviceState *qd = bc->child;
> +        XScomDevice *xd = XSCOM_DEVICE(qd);
> +        XScomDeviceClass *xc = XSCOM_DEVICE_GET_CLASS(xd);
> +        uint32_t reg[MAX_XSCOM_RANGES * 2];
> +        unsigned int i, sz = 0;
> +        void *cp, *p;
> +
> +        /* Some XSCOM slaves may not be represented in the DT */
> +        if (!xc->dt_name) {
> +            continue;
> +        }
> +        name = g_strdup_printf("address@hidden", xc->dt_name, 
> xd->ranges[0].addr);
> +        _FDT((fdt_begin_node(fdt, name)));
> +        g_free(name);
> +        for (i = 0; i < MAX_XSCOM_RANGES; i++) {
> +            if (xd->ranges[i].size == 0) {
> +                break;
> +            }
> +            reg[sz++] = cpu_to_be32(xd->ranges[i].addr);
> +            reg[sz++] = cpu_to_be32(xd->ranges[i].size);
> +        }
> +        _FDT((fdt_property(fdt, "reg", reg, sz * 4)));
> +        if (xc->devnode) {
> +            _FDT((xc->devnode(xd, fdt)));
> +        }
> +#define MAX_COMPATIBLE_PROP     1024
> +        cp = p = g_malloc0(MAX_COMPATIBLE_PROP);
> +        i = 0;
> +        while((p - cp) < MAX_COMPATIBLE_PROP) {
> +            int l;
> +            if (xc->dt_compatible[i] == NULL) {
> +                break;
> +            }
> +            l = strlen(xc->dt_compatible[i]);
> +            if (l >= (MAX_COMPATIBLE_PROP - i)) {
> +                break;
> +            }
> +            strcpy(p, xc->dt_compatible[i++]);
> +            p += l + 1;
> +        }
> +        _FDT((fdt_property(fdt, "compatible", cp, p - cp)));
> +        _FDT((fdt_end_node(fdt)));
> +    }
> +
> +    _FDT((fdt_end_node(fdt)));
> +
> +    return 0;
> +}
> +
> +static int xscom_qdev_init(DeviceState *qdev)
> +{
> +    XScomDevice *xdev = (XScomDevice *)qdev;
> +    XScomDeviceClass *xc = XSCOM_DEVICE_GET_CLASS(xdev);
> +
> +    if (xc->init) {
> +        return xc->init(xdev);
> +    }
> +    return 0;
> +}
> +
> +static void xscom_device_class_init(ObjectClass *klass, void *data)
> +{
> +    DeviceClass *k = DEVICE_CLASS(klass);
> +    k->init = xscom_qdev_init;
> +    k->bus_type = TYPE_XSCOM_BUS;
> +}
> +
> +static const TypeInfo xscom_dev_info = {
> +    .name = TYPE_XSCOM_DEVICE,
> +    .parent = TYPE_DEVICE,
> +    .instance_size = sizeof(XScomDevice),
> +    .abstract = true,
> +    .class_size = sizeof(XScomDeviceClass),
> +    .class_init = xscom_device_class_init,
> +};
> +
> +static void xscom_register_types(void)
> +{
> +    type_register_static(&xscom_info);
> +    type_register_static(&xscom_bus_info);
> +    type_register_static(&xscom_dev_info);
> +}
> +
> +type_init(xscom_register_types)
> +
> diff --git a/include/hw/ppc/pnv.h b/include/hw/ppc/pnv.h
> index 9a48c16..cb157eb 100644
> --- a/include/hw/ppc/pnv.h
> +++ b/include/hw/ppc/pnv.h
> @@ -20,10 +20,12 @@
>   */
>  
>  #include "hw/hw.h"
> +typedef struct XScomBus XScomBus;
>  
>  /* Should we turn that into a QOjb of some sort ? */
>  typedef struct PnvChip {
>      uint32_t         chip_id;
> +    XScomBus         *xscom;
>  } PnvChip;
>  
>  typedef struct PnvSystem {
> diff --git a/include/hw/ppc/pnv_xscom.h b/include/hw/ppc/pnv_xscom.h
> new file mode 100644
> index 0000000..99de078
> --- /dev/null
> +++ b/include/hw/ppc/pnv_xscom.h
> @@ -0,0 +1,73 @@
> +#ifndef _HW_XSCOM_H
> +#define _HW_XSCOM_H
> +/*
> + * QEMU PowerNV XSCOM bus definitions
> + *
> + * Copyright (c) 2010 David Gibson, IBM Corporation <address@hidden>
> + * Based on the s390 virtio bus definitions:
> + * Copyright (c) 2009 Alexander Graf <address@hidden>
> + *
> + * This library is free software; you can redistribute it and/or
> + * modify it under the terms of the GNU Lesser General Public
> + * License as published by the Free Software Foundation; either
> + * version 2 of the License, or (at your option) any later version.
> + *
> + * This library is distributed in the hope that it will be useful,
> + * but WITHOUT ANY WARRANTY; without even the implied warranty of
> + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
> + * Lesser General Public License for more details.
> + *
> + * You should have received a copy of the GNU Lesser General Public
> + * License along with this library; if not, see 
> <http://www.gnu.org/licenses/>.
> + */
> +
> +#include <hw/ppc/pnv.h>
> +
> +#define TYPE_XSCOM_DEVICE "xscom-device"
> +#define XSCOM_DEVICE(obj) \
> +     OBJECT_CHECK(XScomDevice, (obj), TYPE_XSCOM_DEVICE)
> +#define XSCOM_DEVICE_CLASS(klass) \
> +     OBJECT_CLASS_CHECK(XScomDeviceClass, (klass), TYPE_XSCOM_DEVICE)
> +#define XSCOM_DEVICE_GET_CLASS(obj) \
> +     OBJECT_GET_CLASS(XScomDeviceClass, (obj), TYPE_XSCOM_DEVICE)
> +
> +#define TYPE_XSCOM_BUS "xscom-bus"
> +#define XSCOM_BUS(obj) OBJECT_CHECK(XScomBus, (obj), TYPE_XSCOM_BUS)
> +
> +typedef struct XScomDevice XScomDevice;
> +typedef struct XScomBus XScomBus;
> +
> +typedef struct XScomDeviceClass {
> +    DeviceClass parent_class;
> +
> +    const char *dt_name;
> +    const char **dt_compatible;
> +    int (*init)(XScomDevice *dev);
> +    int (*devnode)(XScomDevice *dev, void *fdt);
> +
> +    /* Actual XScom accesses */
> +    bool (*read)(XScomDevice *dev, uint32_t range, uint32_t offset, uint64_t 
> *out_val);
> +    bool (*write)(XScomDevice *dev, uint32_t range, uint32_t offset, 
> uint64_t val);
> +} XScomDeviceClass;
> +
> +typedef struct XScomRange {
> +    uint32_t addr;
> +    uint32_t size;
> +} XScomRange;
> +
> +struct XScomDevice {
> +    DeviceState qdev;
> +#define MAX_XSCOM_RANGES     4
> +    struct XScomRange ranges[MAX_XSCOM_RANGES];
> +};
> +
> +struct XScomBus {
> +    BusState bus;
> +    uint32_t chip_id;
> +};
> +
> +extern void xscom_create(PnvChip *chip);
> +extern int xscom_populate_fdt(XScomBus *xscom, void *fdt);
> +
> +
> +#endif /* _HW_XSCOM_H */

-- 
David Gibson                    | I'll have my music baroque, and my code
david AT gibson.dropbear.id.au  | minimalist, thank you.  NOT _the_ _other_
                                | _way_ _around_!
http://www.ozlabs.org/~dgibson

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