diff mbox

[v4,2/8] bcm2835_property: add bcm2835 property channel

Message ID 1452902337-13844-3-git-send-email-Andrew.Baumann@microsoft.com (mailing list archive)
State New, archived
Headers show

Commit Message

Andrew Baumann Jan. 15, 2016, 11:58 p.m. UTC 
This sits behind the mailbox interface, and implements
request/response queries for system properties. The
framebuffer-related properties will be added in a later patch.

Signed-off-by: Andrew Baumann <Andrew.Baumann@microsoft.com>
---

Notes:
    v4:
    * added LOG_UNIMP as appropriate
    * use qemu_macaddr_default_if_unset to allocate a MAC address, and dma_memory_write to write it
    * assert that we're not pending, rather than dropping a request on the floor

 hw/misc/Makefile.objs              |   1 +
 hw/misc/bcm2835_property.c         | 286 +++++++++++++++++++++++++++++++++++++
 include/hw/misc/bcm2835_property.h |  31 ++++
 3 files changed, 318 insertions(+)
 create mode 100644 hw/misc/bcm2835_property.c
 create mode 100644 include/hw/misc/bcm2835_property.h

Comments

Peter Crosthwaite Jan. 26, 2016, 6:03 a.m. UTC | #1 
On Fri, Jan 15, 2016 at 3:58 PM, Andrew Baumann
<Andrew.Baumann@microsoft.com> wrote:
> This sits behind the mailbox interface, and implements
> request/response queries for system properties. The
> framebuffer-related properties will be added in a later patch.
>
> Signed-off-by: Andrew Baumann <Andrew.Baumann@microsoft.com>
> ---
>
> Notes:
>     v4:
>     * added LOG_UNIMP as appropriate
>     * use qemu_macaddr_default_if_unset to allocate a MAC address, and dma_memory_write to write it
>     * assert that we're not pending, rather than dropping a request on the floor
>
>  hw/misc/Makefile.objs              |   1 +
>  hw/misc/bcm2835_property.c         | 286 +++++++++++++++++++++++++++++++++++++
>  include/hw/misc/bcm2835_property.h |  31 ++++
>  3 files changed, 318 insertions(+)
>  create mode 100644 hw/misc/bcm2835_property.c
>  create mode 100644 include/hw/misc/bcm2835_property.h
>
> diff --git a/hw/misc/Makefile.objs b/hw/misc/Makefile.objs
> index d0ea105..ea6cd3c 100644
> --- a/hw/misc/Makefile.objs
> +++ b/hw/misc/Makefile.objs
> @@ -37,6 +37,7 @@ obj-$(CONFIG_OMAP) += omap_l4.o
>  obj-$(CONFIG_OMAP) += omap_sdrc.o
>  obj-$(CONFIG_OMAP) += omap_tap.o
>  obj-$(CONFIG_RASPI) += bcm2835_mbox.o
> +obj-$(CONFIG_RASPI) += bcm2835_property.o
>  obj-$(CONFIG_SLAVIO) += slavio_misc.o
>  obj-$(CONFIG_ZYNQ) += zynq_slcr.o
>  obj-$(CONFIG_ZYNQ) += zynq-xadc.o
> diff --git a/hw/misc/bcm2835_property.c b/hw/misc/bcm2835_property.c
> new file mode 100644
> index 0000000..52c9b8d
> --- /dev/null
> +++ b/hw/misc/bcm2835_property.c
> @@ -0,0 +1,286 @@
> +/*
> + * Raspberry Pi emulation (c) 2012 Gregory Estrade
> + * This code is licensed under the GNU GPLv2 and later.
> + */
> +
> +#include "hw/misc/bcm2835_property.h"
> +#include "hw/misc/bcm2835_mbox_defs.h"
> +#include "sysemu/dma.h"
> +
> +/* https://github.com/raspberrypi/firmware/wiki/Mailbox-property-interface */
> +
> +static void bcm2835_property_mbox_push(BCM2835PropertyState *s, uint32_t value)
> +{
> +    uint32_t tag;
> +    uint32_t bufsize;
> +    uint32_t tot_len;
> +    size_t resplen;
> +    uint32_t tmp;
> +
> +    value &= ~0xf;
> +
> +    s->addr = value;
> +
> +    tot_len = ldl_phys(&s->dma_as, value);
> +
> +    /* @(addr + 4) : Buffer response code */
> +    value = s->addr + 8;
> +    while (value + 8 <= s->addr + tot_len) {
> +        tag = ldl_phys(&s->dma_as, value);
> +        bufsize = ldl_phys(&s->dma_as, value + 4);
> +        /* @(value + 8) : Request/response indicator */
> +        resplen = 0;
> +        switch (tag) {
> +        case 0x00000000: /* End tag */
> +            break;
> +        case 0x00000001: /* Get firmware revision */
> +            stl_phys(&s->dma_as, value + 12, 346337);
> +            resplen = 4;
> +            break;
> +        case 0x00010001: /* Get board model */
> +            qemu_log_mask(LOG_UNIMP,
> +                          "bcm2835_property: %x get board model NYI\n", tag);
> +            resplen = 4;
> +            break;
> +        case 0x00010002: /* Get board revision */
> +            qemu_log_mask(LOG_UNIMP,
> +                          "bcm2835_property: %x get board revision NYI\n", tag);
> +            resplen = 4;
> +            break;
> +        case 0x00010003: /* Get board MAC address */
> +            resplen = sizeof(s->macaddr.a);
> +            dma_memory_write(&s->dma_as, value + 12, s->macaddr.a, resplen);
> +            break;
> +        case 0x00010004: /* Get board serial */
> +            qemu_log_mask(LOG_UNIMP,
> +                          "bcm2835_property: %x get board serial NYI\n", tag);
> +            resplen = 8;
> +            break;
> +        case 0x00010005: /* Get ARM memory */
> +            /* base */
> +            stl_phys(&s->dma_as, value + 12, 0);
> +            /* size */
> +            stl_phys(&s->dma_as, value + 16, s->ram_size);
> +            resplen = 8;
> +            break;
> +        case 0x00028001: /* Set power state */
> +            /* Assume that whatever device they asked for exists,
> +             * and we'll just claim we set it to the desired state */

blank before */

A grep on "^\+[ \t]*\*.*\*\/$" on the patch series will catch-all.

Otherwise,

Reviewed-by: Peter Crosthwaite <crosthwaite.peter@gmail.com>

Regards,
Peter

> +            tmp = ldl_phys(&s->dma_as, value + 16);
> +            stl_phys(&s->dma_as, value + 16, (tmp & 1));
> +            resplen = 8;
> +            break;
> +
> +        /* Clocks */
> +
> +        case 0x00030001: /* Get clock state */
> +            stl_phys(&s->dma_as, value + 16, 0x1);
> +            resplen = 8;
> +            break;
> +
> +        case 0x00038001: /* Set clock state */
> +            qemu_log_mask(LOG_UNIMP,
> +                          "bcm2835_property: %x set clock state NYI\n", tag);
> +            resplen = 8;
> +            break;
> +
> +        case 0x00030002: /* Get clock rate */
> +        case 0x00030004: /* Get max clock rate */
> +        case 0x00030007: /* Get min clock rate */
> +            switch (ldl_phys(&s->dma_as, value + 12)) {
> +            case 1: /* EMMC */
> +                stl_phys(&s->dma_as, value + 16, 50000000);
> +                break;
> +            case 2: /* UART */
> +                stl_phys(&s->dma_as, value + 16, 3000000);
> +                break;
> +            default:
> +                stl_phys(&s->dma_as, value + 16, 700000000);
> +                break;
> +            }
> +            resplen = 8;
> +            break;
> +
> +        case 0x00038002: /* Set clock rate */
> +        case 0x00038004: /* Set max clock rate */
> +        case 0x00038007: /* Set min clock rate */
> +            qemu_log_mask(LOG_UNIMP,
> +                          "bcm2835_property: %x set clock rates NYI\n", tag);
> +            resplen = 8;
> +            break;
> +
> +        /* Temperature */
> +
> +        case 0x00030006: /* Get temperature */
> +            stl_phys(&s->dma_as, value + 16, 25000);
> +            resplen = 8;
> +            break;
> +
> +        case 0x0003000A: /* Get max temperature */
> +            stl_phys(&s->dma_as, value + 16, 99000);
> +            resplen = 8;
> +            break;
> +
> +
> +        case 0x00060001: /* Get DMA channels */
> +            /* channels 2-5 */
> +            stl_phys(&s->dma_as, value + 12, 0x003C);
> +            resplen = 4;
> +            break;
> +
> +        case 0x00050001: /* Get command line */
> +            resplen = 0;
> +            break;
> +
> +        default:
> +            qemu_log_mask(LOG_GUEST_ERROR,
> +                          "bcm2835_property: unhandled tag %08x\n", tag);
> +            break;
> +        }
> +
> +        if (tag == 0) {
> +            break;
> +        }
> +
> +        stl_phys(&s->dma_as, value + 8, (1 << 31) | resplen);
> +        value += bufsize + 12;
> +    }
> +
> +    /* Buffer response code */
> +    stl_phys(&s->dma_as, s->addr + 4, (1 << 31));
> +}
> +
> +static uint64_t bcm2835_property_read(void *opaque, hwaddr offset,
> +                                      unsigned size)
> +{
> +    BCM2835PropertyState *s = opaque;
> +    uint32_t res = 0;
> +
> +    switch (offset) {
> +    case MBOX_AS_DATA:
> +        res = MBOX_CHAN_PROPERTY | s->addr;
> +        s->pending = false;
> +        qemu_set_irq(s->mbox_irq, 0);
> +        break;
> +
> +    case MBOX_AS_PENDING:
> +        res = s->pending;
> +        break;
> +
> +    default:
> +        qemu_log_mask(LOG_GUEST_ERROR, "%s: Bad offset %"HWADDR_PRIx"\n",
> +                      __func__, offset);
> +        return 0;
> +    }
> +
> +    return res;
> +}
> +
> +static void bcm2835_property_write(void *opaque, hwaddr offset,
> +                                   uint64_t value, unsigned size)
> +{
> +    BCM2835PropertyState *s = opaque;
> +
> +    switch (offset) {
> +    case MBOX_AS_DATA:
> +        /* bcm2835_mbox should check our pending status before pushing */
> +        assert(!s->pending);
> +        s->pending = true;
> +        bcm2835_property_mbox_push(s, value);
> +        qemu_set_irq(s->mbox_irq, 1);
> +        break;
> +
> +    default:
> +        qemu_log_mask(LOG_GUEST_ERROR, "%s: Bad offset %"HWADDR_PRIx"\n",
> +                      __func__, offset);
> +        return;
> +    }
> +}
> +
> +static const MemoryRegionOps bcm2835_property_ops = {
> +    .read = bcm2835_property_read,
> +    .write = bcm2835_property_write,
> +    .endianness = DEVICE_NATIVE_ENDIAN,
> +    .valid.min_access_size = 4,
> +    .valid.max_access_size = 4,
> +};
> +
> +static const VMStateDescription vmstate_bcm2835_property = {
> +    .name = TYPE_BCM2835_PROPERTY,
> +    .version_id = 1,
> +    .minimum_version_id = 1,
> +    .fields      = (VMStateField[]) {
> +        VMSTATE_MACADDR(macaddr, BCM2835PropertyState),
> +        VMSTATE_UINT32(addr, BCM2835PropertyState),
> +        VMSTATE_BOOL(pending, BCM2835PropertyState),
> +        VMSTATE_END_OF_LIST()
> +    }
> +};
> +
> +static void bcm2835_property_init(Object *obj)
> +{
> +    BCM2835PropertyState *s = BCM2835_PROPERTY(obj);
> +
> +    memory_region_init_io(&s->iomem, OBJECT(s), &bcm2835_property_ops, s,
> +                          TYPE_BCM2835_PROPERTY, 0x10);
> +    sysbus_init_mmio(SYS_BUS_DEVICE(s), &s->iomem);
> +    sysbus_init_irq(SYS_BUS_DEVICE(s), &s->mbox_irq);
> +}
> +
> +static void bcm2835_property_reset(DeviceState *dev)
> +{
> +    BCM2835PropertyState *s = BCM2835_PROPERTY(dev);
> +
> +    s->pending = false;
> +}
> +
> +static void bcm2835_property_realize(DeviceState *dev, Error **errp)
> +{
> +    BCM2835PropertyState *s = BCM2835_PROPERTY(dev);
> +    Object *obj;
> +    Error *err = NULL;
> +
> +    obj = object_property_get_link(OBJECT(dev), "dma-mr", &err);
> +    if (obj == NULL) {
> +        error_setg(errp, "%s: required dma-mr link not found: %s",
> +                   __func__, error_get_pretty(err));
> +        return;
> +    }
> +
> +    s->dma_mr = MEMORY_REGION(obj);
> +    address_space_init(&s->dma_as, s->dma_mr, NULL);
> +
> +    /* TODO: connect to MAC address of USB NIC device, once we emulate it */
> +    qemu_macaddr_default_if_unset(&s->macaddr);
> +
> +    bcm2835_property_reset(dev);
> +}
> +
> +static Property bcm2835_property_props[] = {
> +    DEFINE_PROP_UINT32("ram-size", BCM2835PropertyState, ram_size, 0),
> +    DEFINE_PROP_END_OF_LIST()
> +};
> +
> +static void bcm2835_property_class_init(ObjectClass *klass, void *data)
> +{
> +    DeviceClass *dc = DEVICE_CLASS(klass);
> +
> +    dc->props = bcm2835_property_props;
> +    dc->realize = bcm2835_property_realize;
> +    dc->vmsd = &vmstate_bcm2835_property;
> +}
> +
> +static TypeInfo bcm2835_property_info = {
> +    .name          = TYPE_BCM2835_PROPERTY,
> +    .parent        = TYPE_SYS_BUS_DEVICE,
> +    .instance_size = sizeof(BCM2835PropertyState),
> +    .class_init    = bcm2835_property_class_init,
> +    .instance_init = bcm2835_property_init,
> +};
> +
> +static void bcm2835_property_register_types(void)
> +{
> +    type_register_static(&bcm2835_property_info);
> +}
> +
> +type_init(bcm2835_property_register_types)
> diff --git a/include/hw/misc/bcm2835_property.h b/include/hw/misc/bcm2835_property.h
> new file mode 100644
> index 0000000..fcf5f3d
> --- /dev/null
> +++ b/include/hw/misc/bcm2835_property.h
> @@ -0,0 +1,31 @@
> +/*
> + * Raspberry Pi emulation (c) 2012 Gregory Estrade
> + * This code is licensed under the GNU GPLv2 and later.
> + */
> +
> +#ifndef BCM2835_PROPERTY_H
> +#define BCM2835_PROPERTY_H
> +
> +#include "hw/sysbus.h"
> +#include "exec/address-spaces.h"
> +#include "net/net.h"
> +
> +#define TYPE_BCM2835_PROPERTY "bcm2835-property"
> +#define BCM2835_PROPERTY(obj) \
> +        OBJECT_CHECK(BCM2835PropertyState, (obj), TYPE_BCM2835_PROPERTY)
> +
> +typedef struct {
> +    /*< private >*/
> +    SysBusDevice busdev;
> +    /*< public >*/
> +    MemoryRegion *dma_mr;
> +    AddressSpace dma_as;
> +    MemoryRegion iomem;
> +    qemu_irq mbox_irq;
> +    MACAddr macaddr;
> +    uint32_t ram_size;
> +    uint32_t addr;
> +    bool pending;
> +} BCM2835PropertyState;
> +
> +#endif
> --
> 2.5.3
>
diff mbox

Patch

diff --git a/hw/misc/Makefile.objs b/hw/misc/Makefile.objs
index d0ea105..ea6cd3c 100644
--- a/hw/misc/Makefile.objs
+++ b/hw/misc/Makefile.objs
@@ -37,6 +37,7 @@  obj-$(CONFIG_OMAP) += omap_l4.o
 obj-$(CONFIG_OMAP) += omap_sdrc.o
 obj-$(CONFIG_OMAP) += omap_tap.o
 obj-$(CONFIG_RASPI) += bcm2835_mbox.o
+obj-$(CONFIG_RASPI) += bcm2835_property.o
 obj-$(CONFIG_SLAVIO) += slavio_misc.o
 obj-$(CONFIG_ZYNQ) += zynq_slcr.o
 obj-$(CONFIG_ZYNQ) += zynq-xadc.o
diff --git a/hw/misc/bcm2835_property.c b/hw/misc/bcm2835_property.c
new file mode 100644
index 0000000..52c9b8d
--- /dev/null
+++ b/hw/misc/bcm2835_property.c
@@ -0,0 +1,286 @@ 
+/*
+ * Raspberry Pi emulation (c) 2012 Gregory Estrade
+ * This code is licensed under the GNU GPLv2 and later.
+ */
+
+#include "hw/misc/bcm2835_property.h"
+#include "hw/misc/bcm2835_mbox_defs.h"
+#include "sysemu/dma.h"
+
+/* https://github.com/raspberrypi/firmware/wiki/Mailbox-property-interface */
+
+static void bcm2835_property_mbox_push(BCM2835PropertyState *s, uint32_t value)
+{
+    uint32_t tag;
+    uint32_t bufsize;
+    uint32_t tot_len;
+    size_t resplen;
+    uint32_t tmp;
+
+    value &= ~0xf;
+
+    s->addr = value;
+
+    tot_len = ldl_phys(&s->dma_as, value);
+
+    /* @(addr + 4) : Buffer response code */
+    value = s->addr + 8;
+    while (value + 8 <= s->addr + tot_len) {
+        tag = ldl_phys(&s->dma_as, value);
+        bufsize = ldl_phys(&s->dma_as, value + 4);
+        /* @(value + 8) : Request/response indicator */
+        resplen = 0;
+        switch (tag) {
+        case 0x00000000: /* End tag */
+            break;
+        case 0x00000001: /* Get firmware revision */
+            stl_phys(&s->dma_as, value + 12, 346337);
+            resplen = 4;
+            break;
+        case 0x00010001: /* Get board model */
+            qemu_log_mask(LOG_UNIMP,
+                          "bcm2835_property: %x get board model NYI\n", tag);
+            resplen = 4;
+            break;
+        case 0x00010002: /* Get board revision */
+            qemu_log_mask(LOG_UNIMP,
+                          "bcm2835_property: %x get board revision NYI\n", tag);
+            resplen = 4;
+            break;
+        case 0x00010003: /* Get board MAC address */
+            resplen = sizeof(s->macaddr.a);
+            dma_memory_write(&s->dma_as, value + 12, s->macaddr.a, resplen);
+            break;
+        case 0x00010004: /* Get board serial */
+            qemu_log_mask(LOG_UNIMP,
+                          "bcm2835_property: %x get board serial NYI\n", tag);
+            resplen = 8;
+            break;
+        case 0x00010005: /* Get ARM memory */
+            /* base */
+            stl_phys(&s->dma_as, value + 12, 0);
+            /* size */
+            stl_phys(&s->dma_as, value + 16, s->ram_size);
+            resplen = 8;
+            break;
+        case 0x00028001: /* Set power state */
+            /* Assume that whatever device they asked for exists,
+             * and we'll just claim we set it to the desired state */
+            tmp = ldl_phys(&s->dma_as, value + 16);
+            stl_phys(&s->dma_as, value + 16, (tmp & 1));
+            resplen = 8;
+            break;
+
+        /* Clocks */
+
+        case 0x00030001: /* Get clock state */
+            stl_phys(&s->dma_as, value + 16, 0x1);
+            resplen = 8;
+            break;
+
+        case 0x00038001: /* Set clock state */
+            qemu_log_mask(LOG_UNIMP,
+                          "bcm2835_property: %x set clock state NYI\n", tag);
+            resplen = 8;
+            break;
+
+        case 0x00030002: /* Get clock rate */
+        case 0x00030004: /* Get max clock rate */
+        case 0x00030007: /* Get min clock rate */
+            switch (ldl_phys(&s->dma_as, value + 12)) {
+            case 1: /* EMMC */
+                stl_phys(&s->dma_as, value + 16, 50000000);
+                break;
+            case 2: /* UART */
+                stl_phys(&s->dma_as, value + 16, 3000000);
+                break;
+            default:
+                stl_phys(&s->dma_as, value + 16, 700000000);
+                break;
+            }
+            resplen = 8;
+            break;
+
+        case 0x00038002: /* Set clock rate */
+        case 0x00038004: /* Set max clock rate */
+        case 0x00038007: /* Set min clock rate */
+            qemu_log_mask(LOG_UNIMP,
+                          "bcm2835_property: %x set clock rates NYI\n", tag);
+            resplen = 8;
+            break;
+
+        /* Temperature */
+
+        case 0x00030006: /* Get temperature */
+            stl_phys(&s->dma_as, value + 16, 25000);
+            resplen = 8;
+            break;
+
+        case 0x0003000A: /* Get max temperature */
+            stl_phys(&s->dma_as, value + 16, 99000);
+            resplen = 8;
+            break;
+
+
+        case 0x00060001: /* Get DMA channels */
+            /* channels 2-5 */
+            stl_phys(&s->dma_as, value + 12, 0x003C);
+            resplen = 4;
+            break;
+
+        case 0x00050001: /* Get command line */
+            resplen = 0;
+            break;
+
+        default:
+            qemu_log_mask(LOG_GUEST_ERROR,
+                          "bcm2835_property: unhandled tag %08x\n", tag);
+            break;
+        }
+
+        if (tag == 0) {
+            break;
+        }
+
+        stl_phys(&s->dma_as, value + 8, (1 << 31) | resplen);
+        value += bufsize + 12;
+    }
+
+    /* Buffer response code */
+    stl_phys(&s->dma_as, s->addr + 4, (1 << 31));
+}
+
+static uint64_t bcm2835_property_read(void *opaque, hwaddr offset,
+                                      unsigned size)
+{
+    BCM2835PropertyState *s = opaque;
+    uint32_t res = 0;
+
+    switch (offset) {
+    case MBOX_AS_DATA:
+        res = MBOX_CHAN_PROPERTY | s->addr;
+        s->pending = false;
+        qemu_set_irq(s->mbox_irq, 0);
+        break;
+
+    case MBOX_AS_PENDING:
+        res = s->pending;
+        break;
+
+    default:
+        qemu_log_mask(LOG_GUEST_ERROR, "%s: Bad offset %"HWADDR_PRIx"\n",
+                      __func__, offset);
+        return 0;
+    }
+
+    return res;
+}
+
+static void bcm2835_property_write(void *opaque, hwaddr offset,
+                                   uint64_t value, unsigned size)
+{
+    BCM2835PropertyState *s = opaque;
+
+    switch (offset) {
+    case MBOX_AS_DATA:
+        /* bcm2835_mbox should check our pending status before pushing */
+        assert(!s->pending);
+        s->pending = true;
+        bcm2835_property_mbox_push(s, value);
+        qemu_set_irq(s->mbox_irq, 1);
+        break;
+
+    default:
+        qemu_log_mask(LOG_GUEST_ERROR, "%s: Bad offset %"HWADDR_PRIx"\n",
+                      __func__, offset);
+        return;
+    }
+}
+
+static const MemoryRegionOps bcm2835_property_ops = {
+    .read = bcm2835_property_read,
+    .write = bcm2835_property_write,
+    .endianness = DEVICE_NATIVE_ENDIAN,
+    .valid.min_access_size = 4,
+    .valid.max_access_size = 4,
+};
+
+static const VMStateDescription vmstate_bcm2835_property = {
+    .name = TYPE_BCM2835_PROPERTY,
+    .version_id = 1,
+    .minimum_version_id = 1,
+    .fields      = (VMStateField[]) {
+        VMSTATE_MACADDR(macaddr, BCM2835PropertyState),
+        VMSTATE_UINT32(addr, BCM2835PropertyState),
+        VMSTATE_BOOL(pending, BCM2835PropertyState),
+        VMSTATE_END_OF_LIST()
+    }
+};
+
+static void bcm2835_property_init(Object *obj)
+{
+    BCM2835PropertyState *s = BCM2835_PROPERTY(obj);
+
+    memory_region_init_io(&s->iomem, OBJECT(s), &bcm2835_property_ops, s,
+                          TYPE_BCM2835_PROPERTY, 0x10);
+    sysbus_init_mmio(SYS_BUS_DEVICE(s), &s->iomem);
+    sysbus_init_irq(SYS_BUS_DEVICE(s), &s->mbox_irq);
+}
+
+static void bcm2835_property_reset(DeviceState *dev)
+{
+    BCM2835PropertyState *s = BCM2835_PROPERTY(dev);
+
+    s->pending = false;
+}
+
+static void bcm2835_property_realize(DeviceState *dev, Error **errp)
+{
+    BCM2835PropertyState *s = BCM2835_PROPERTY(dev);
+    Object *obj;
+    Error *err = NULL;
+
+    obj = object_property_get_link(OBJECT(dev), "dma-mr", &err);
+    if (obj == NULL) {
+        error_setg(errp, "%s: required dma-mr link not found: %s",
+                   __func__, error_get_pretty(err));
+        return;
+    }
+
+    s->dma_mr = MEMORY_REGION(obj);
+    address_space_init(&s->dma_as, s->dma_mr, NULL);
+
+    /* TODO: connect to MAC address of USB NIC device, once we emulate it */
+    qemu_macaddr_default_if_unset(&s->macaddr);
+
+    bcm2835_property_reset(dev);
+}
+
+static Property bcm2835_property_props[] = {
+    DEFINE_PROP_UINT32("ram-size", BCM2835PropertyState, ram_size, 0),
+    DEFINE_PROP_END_OF_LIST()
+};
+
+static void bcm2835_property_class_init(ObjectClass *klass, void *data)
+{
+    DeviceClass *dc = DEVICE_CLASS(klass);
+
+    dc->props = bcm2835_property_props;
+    dc->realize = bcm2835_property_realize;
+    dc->vmsd = &vmstate_bcm2835_property;
+}
+
+static TypeInfo bcm2835_property_info = {
+    .name          = TYPE_BCM2835_PROPERTY,
+    .parent        = TYPE_SYS_BUS_DEVICE,
+    .instance_size = sizeof(BCM2835PropertyState),
+    .class_init    = bcm2835_property_class_init,
+    .instance_init = bcm2835_property_init,
+};
+
+static void bcm2835_property_register_types(void)
+{
+    type_register_static(&bcm2835_property_info);
+}
+
+type_init(bcm2835_property_register_types)
diff --git a/include/hw/misc/bcm2835_property.h b/include/hw/misc/bcm2835_property.h
new file mode 100644
index 0000000..fcf5f3d
--- /dev/null
+++ b/include/hw/misc/bcm2835_property.h
@@ -0,0 +1,31 @@ 
+/*
+ * Raspberry Pi emulation (c) 2012 Gregory Estrade
+ * This code is licensed under the GNU GPLv2 and later.
+ */
+
+#ifndef BCM2835_PROPERTY_H
+#define BCM2835_PROPERTY_H
+
+#include "hw/sysbus.h"
+#include "exec/address-spaces.h"
+#include "net/net.h"
+
+#define TYPE_BCM2835_PROPERTY "bcm2835-property"
+#define BCM2835_PROPERTY(obj) \
+        OBJECT_CHECK(BCM2835PropertyState, (obj), TYPE_BCM2835_PROPERTY)
+
+typedef struct {
+    /*< private >*/
+    SysBusDevice busdev;
+    /*< public >*/
+    MemoryRegion *dma_mr;
+    AddressSpace dma_as;
+    MemoryRegion iomem;
+    qemu_irq mbox_irq;
+    MACAddr macaddr;
+    uint32_t ram_size;
+    uint32_t addr;
+    bool pending;
+} BCM2835PropertyState;
+
+#endif