diff mbox

[v2,5/5] bcm2835_dma: add emulation of Raspberry Pi DMA controller

Message ID 1457029479-11312-6-git-send-email-Andrew.Baumann@microsoft.com (mailing list archive)
State New, archived
Headers show

Commit Message

Andrew Baumann March 3, 2016, 6:24 p.m. UTC
At present, all DMA transfers complete inline (so a looping descriptor
queue will lock up the device). We also do not model pause/abort,
arbitrarion/priority, or debug features.

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

Notes:
    v2:
     * avoid ldl_phys/stl_phys
     * compute address of channel structure only after asserting its validity
     * correctly implement per-channel reset and abort bits
     * set channel paused bit when completing DMA

 hw/arm/bcm2835_peripherals.c         |  26 +++
 hw/dma/Makefile.objs                 |   1 +
 hw/dma/bcm2835_dma.c                 | 408 +++++++++++++++++++++++++++++++++++
 include/hw/arm/bcm2835_peripherals.h |   2 +
 include/hw/dma/bcm2835_dma.h         |  47 ++++
 5 files changed, 484 insertions(+)
 create mode 100644 hw/dma/bcm2835_dma.c
 create mode 100644 include/hw/dma/bcm2835_dma.h

Comments

Peter Maydell March 8, 2016, 4:36 a.m. UTC | #1
On 4 March 2016 at 01:24, Andrew Baumann <Andrew.Baumann@microsoft.com> wrote:
> At present, all DMA transfers complete inline (so a looping descriptor
> queue will lock up the device). We also do not model pause/abort,
> arbitrarion/priority, or debug features.
>
> Signed-off-by: Andrew Baumann <Andrew.Baumann@microsoft.com>
> ---

Reviewed-by: Peter Maydell <peter.maydell@linaro.org>

Can you add Gregory's Signed-off-by (and authorship from?) to whichever
patches are appropriate when you resend (as per discussion on the
earlier version of this patch)?

thanks
-- PMM
Andrew Baumann March 8, 2016, 5:23 a.m. UTC | #2
> From: Peter Maydell [mailto:peter.maydell@linaro.org]

> Sent: Monday, 7 March 2016 8:37 PM

> 

> On 4 March 2016 at 01:24, Andrew Baumann

> <Andrew.Baumann@microsoft.com> wrote:

> > At present, all DMA transfers complete inline (so a looping descriptor

> > queue will lock up the device). We also do not model pause/abort,

> > arbitrarion/priority, or debug features.

> >

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

> > ---

> 

> Reviewed-by: Peter Maydell <peter.maydell@linaro.org>

> 

> Can you add Gregory's Signed-off-by (and authorship from?) to whichever

> patches are appropriate when you resend (as per discussion on the

> earlier version of this patch)?


Yes, happily. But what's the best way to capture this when the code we're committing is a mixture of code from Gregory and Stefan (via a manual patch into Stefan's ar7 repo, so much of that history is lost to me) that I've then extended and refactored? I know what I added (e.g. aux), but for the files with joint authorship (fb, dma) should we just put Gregory as the author on those patches with a signed-off-by from me? Can I also add a signed-off-by on behalf of Gregory, or does he need to do it?

Forgive the newbie questions, but I'm new to this process and want to get it right :)

Note that we didn't do this for the previous patch series. Mea culpa. If there's a good way to go back and correct history, I'm happy to help.

Thanks,
Andrew
Peter Maydell March 8, 2016, 5:48 a.m. UTC | #3
On 8 March 2016 at 12:23, Andrew Baumann <Andrew.Baumann@microsoft.com> wrote:
>> From: Peter Maydell [mailto:peter.maydell@linaro.org]
>> Sent: Monday, 7 March 2016 8:37 PM
>>
>> On 4 March 2016 at 01:24, Andrew Baumann
>> <Andrew.Baumann@microsoft.com> wrote:
>> > At present, all DMA transfers complete inline (so a looping descriptor
>> > queue will lock up the device). We also do not model pause/abort,
>> > arbitrarion/priority, or debug features.
>> >
>> > Signed-off-by: Andrew Baumann <Andrew.Baumann@microsoft.com>
>> > ---
>>
>> Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
>>
>> Can you add Gregory's Signed-off-by (and authorship from?) to whichever
>> patches are appropriate when you resend (as per discussion on the
>> earlier version of this patch)?
>
> Yes, happily. But what's the best way to capture this when the code we're
> committing is a mixture of code from Gregory and Stefan (via a manual patch
> into Stefan's ar7 repo, so much of that history is lost to me) that I've
> then extended and refactored? I know what I added (e.g. aux), but for the
> files with joint authorship (fb, dma) should we just put Gregory as the
> author on those patches with a signed-off-by from me? Can I also add a
> signed-off-by on behalf of Gregory, or does he need to do it?

Gregory said an s-o-by from him was OK in the mail thread, so that's
sufficient for you to be able to add it.

The usual approach for multiple authors is that you have the author
be the original or major author, and then the signed-off-by section
looks like:
 Signed-off-by: Original Author <o.author@wherever.org>
 [XYZ: changed foo, bar, baz]
 Signed-off-by: XY Zed <xyz@other.org>

which preserves credit for the original author's work and also a
record of what changes have been made by the next person in the
chain.

If you search in 'git log' for "[PMM" you'll find a bunch of examples
of when I've done it in the past, eg commit f0c02d15b57da6.

(Overall there are two aspects to the signoff lines:
 a: the legal aspect, where you're agreeing to the stuff in the
 Developer's Certificate of Origin; one of the options in there
 is "this code is under an acceptable license that allows me to
 contribute it", so taking some out-of-tree open source code from
 somebody else, fixing it up and sending it in with just your
 signoff is perfectly fine from the strict legal/traceability
 point of view.

 b: credit for work done. This is a social/interpersonal question,
 so there aren't any hard and fast rules, but generally I find the
 best approach is to ask the original authors for their preferences[*],
 let them know in advance about what you're planning and err on
 the side of giving them authorship and other credit rather than
 yourself, while also being clear about what you've done that they
 should not be blamed for.
 [*] Occasionally somebody actually prefers not to be credited
 via signoff because they feel they're now a long way removed from
 what it was.
)

thanks
-- PMM
diff mbox

Patch

diff --git a/hw/arm/bcm2835_peripherals.c b/hw/arm/bcm2835_peripherals.c
index 9b9de99..eeb4934 100644
--- a/hw/arm/bcm2835_peripherals.c
+++ b/hw/arm/bcm2835_peripherals.c
@@ -89,6 +89,14 @@  static void bcm2835_peripherals_init(Object *obj)
     object_initialize(&s->sdhci, sizeof(s->sdhci), TYPE_SYSBUS_SDHCI);
     object_property_add_child(obj, "sdhci", OBJECT(&s->sdhci), NULL);
     qdev_set_parent_bus(DEVICE(&s->sdhci), sysbus_get_default());
+
+    /* DMA Channels */
+    object_initialize(&s->dma, sizeof(s->dma), TYPE_BCM2835_DMA);
+    object_property_add_child(obj, "dma", OBJECT(&s->dma), NULL);
+    qdev_set_parent_bus(DEVICE(&s->dma), sysbus_get_default());
+
+    object_property_add_const_link(OBJECT(&s->dma), "dma-mr",
+                                   OBJECT(&s->gpu_bus_mr), &error_abort);
 }
 
 static void bcm2835_peripherals_realize(DeviceState *dev, Error **errp)
@@ -257,6 +265,24 @@  static void bcm2835_peripherals_realize(DeviceState *dev, Error **errp)
         return;
     }
 
+    /* DMA Channels */
+    object_property_set_bool(OBJECT(&s->dma), true, "realized", &err);
+    if (err) {
+        error_propagate(errp, err);
+        return;
+    }
+
+    memory_region_add_subregion(&s->peri_mr, DMA_OFFSET,
+                sysbus_mmio_get_region(SYS_BUS_DEVICE(&s->dma), 0));
+    memory_region_add_subregion(&s->peri_mr, DMA15_OFFSET,
+                sysbus_mmio_get_region(SYS_BUS_DEVICE(&s->dma), 1));
+
+    for (n = 0; n <= 12; n++) {
+        sysbus_connect_irq(SYS_BUS_DEVICE(&s->dma), n,
+                           qdev_get_gpio_in_named(DEVICE(&s->ic),
+                                                  BCM2835_IC_GPU_IRQ,
+                                                  INTERRUPT_DMA0 + n));
+    }
 }
 
 static void bcm2835_peripherals_class_init(ObjectClass *oc, void *data)
diff --git a/hw/dma/Makefile.objs b/hw/dma/Makefile.objs
index 0e65ed0..a1abbcf 100644
--- a/hw/dma/Makefile.objs
+++ b/hw/dma/Makefile.objs
@@ -11,3 +11,4 @@  common-obj-$(CONFIG_SUN4M) += sun4m_iommu.o
 
 obj-$(CONFIG_OMAP) += omap_dma.o soc_dma.o
 obj-$(CONFIG_PXA2XX) += pxa2xx_dma.o
+obj-$(CONFIG_RASPI) += bcm2835_dma.o
diff --git a/hw/dma/bcm2835_dma.c b/hw/dma/bcm2835_dma.c
new file mode 100644
index 0000000..c7ce4e4
--- /dev/null
+++ b/hw/dma/bcm2835_dma.c
@@ -0,0 +1,408 @@ 
+/*
+ * Raspberry Pi emulation (c) 2012 Gregory Estrade
+ * This code is licensed under the GNU GPLv2 and later.
+ */
+
+#include "qemu/osdep.h"
+#include "hw/dma/bcm2835_dma.h"
+
+/* DMA CS Control and Status bits */
+#define BCM2708_DMA_ACTIVE      (1 << 0)
+#define BCM2708_DMA_END         (1 << 1) /* GE */
+#define BCM2708_DMA_INT         (1 << 2)
+#define BCM2708_DMA_ISPAUSED    (1 << 4)  /* Pause requested or not active */
+#define BCM2708_DMA_ISHELD      (1 << 5)  /* Is held by DREQ flow control */
+#define BCM2708_DMA_ERR         (1 << 8)
+#define BCM2708_DMA_ABORT       (1 << 30) /* stop current CB, go to next, WO */
+#define BCM2708_DMA_RESET       (1 << 31) /* WO, self clearing */
+
+/* DMA control block "info" field bits */
+#define BCM2708_DMA_INT_EN      (1 << 0)
+#define BCM2708_DMA_TDMODE      (1 << 1)
+#define BCM2708_DMA_WAIT_RESP   (1 << 3)
+#define BCM2708_DMA_D_INC       (1 << 4)
+#define BCM2708_DMA_D_WIDTH     (1 << 5)
+#define BCM2708_DMA_D_DREQ      (1 << 6)
+#define BCM2708_DMA_D_IGNORE    (1 << 7)
+#define BCM2708_DMA_S_INC       (1 << 8)
+#define BCM2708_DMA_S_WIDTH     (1 << 9)
+#define BCM2708_DMA_S_DREQ      (1 << 10)
+#define BCM2708_DMA_S_IGNORE    (1 << 11)
+
+/* Register offsets */
+#define BCM2708_DMA_CS          0x00 /* Control and Status */
+#define BCM2708_DMA_ADDR        0x04 /* Control block address */
+/* the current control block appears in the following registers - read only */
+#define BCM2708_DMA_INFO        0x08
+#define BCM2708_DMA_SOURCE_AD   0x0c
+#define BCM2708_DMA_DEST_AD     0x10
+#define BCM2708_DMA_TXFR_LEN    0x14
+#define BCM2708_DMA_STRIDE      0x18
+#define BCM2708_DMA_NEXTCB      0x1C
+#define BCM2708_DMA_DEBUG       0x20
+
+#define BCM2708_DMA_INT_STATUS  0xfe0 /* Interrupt status of each channel */
+#define BCM2708_DMA_ENABLE      0xff0 /* Global enable bits for each channel */
+
+#define BCM2708_DMA_CS_RW_MASK  0x30ff0001 /* All RW bits in DMA_CS */
+
+static void bcm2835_dma_update(BCM2835DMAState *s, unsigned c)
+{
+    BCM2835DMAChan *ch = &s->chan[c];
+    uint32_t data, xlen, ylen;
+    int16_t dst_stride, src_stride;
+
+    if (!(s->enable & (1 << c))) {
+        return;
+    }
+
+    while ((s->enable & (1 << c)) && (ch->conblk_ad != 0)) {
+        /* CB fetch */
+        ch->ti = ldl_le_phys(&s->dma_as, ch->conblk_ad);
+        ch->source_ad = ldl_le_phys(&s->dma_as, ch->conblk_ad + 4);
+        ch->dest_ad = ldl_le_phys(&s->dma_as, ch->conblk_ad + 8);
+        ch->txfr_len = ldl_le_phys(&s->dma_as, ch->conblk_ad + 12);
+        ch->stride = ldl_le_phys(&s->dma_as, ch->conblk_ad + 16);
+        ch->nextconbk = ldl_le_phys(&s->dma_as, ch->conblk_ad + 20);
+
+        if (ch->ti & BCM2708_DMA_TDMODE) {
+            /* 2D transfer mode */
+            ylen = (ch->txfr_len >> 16) & 0x3fff;
+            xlen = ch->txfr_len & 0xffff;
+            dst_stride = ch->stride >> 16;
+            src_stride = ch->stride & 0xffff;
+        } else {
+            ylen = 1;
+            xlen = ch->txfr_len;
+            dst_stride = 0;
+            src_stride = 0;
+        }
+
+        while (ylen != 0) {
+            /* Normal transfer mode */
+            while (xlen != 0) {
+                if (ch->ti & BCM2708_DMA_S_IGNORE) {
+                    /* Ignore reads */
+                    data = 0;
+                } else {
+                    data = ldl_le_phys(&s->dma_as, ch->source_ad);
+                }
+                if (ch->ti & BCM2708_DMA_S_INC) {
+                    ch->source_ad += 4;
+                }
+
+                if (ch->ti & BCM2708_DMA_D_IGNORE) {
+                    /* Ignore writes */
+                } else {
+                    stl_le_phys(&s->dma_as, ch->dest_ad, data);
+                }
+                if (ch->ti & BCM2708_DMA_D_INC) {
+                    ch->dest_ad += 4;
+                }
+
+                /* update remaining transfer length */
+                xlen -= 4;
+                if (ch->ti & BCM2708_DMA_TDMODE) {
+                    ch->txfr_len = (ylen << 16) | xlen;
+                } else {
+                    ch->txfr_len = xlen;
+                }
+            }
+
+            if (--ylen != 0) {
+                ch->source_ad += src_stride;
+                ch->dest_ad += dst_stride;
+            }
+        }
+        ch->cs |= BCM2708_DMA_END;
+        if (ch->ti & BCM2708_DMA_INT_EN) {
+            ch->cs |= BCM2708_DMA_INT;
+            s->int_status |= (1 << c);
+            qemu_set_irq(ch->irq, 1);
+        }
+
+        /* Process next CB */
+        ch->conblk_ad = ch->nextconbk;
+    }
+
+    ch->cs &= ~BCM2708_DMA_ACTIVE;
+    ch->cs |= BCM2708_DMA_ISPAUSED;
+}
+
+static void bcm2835_dma_chan_reset(BCM2835DMAChan *ch)
+{
+    ch->cs = 0;
+    ch->conblk_ad = 0;
+}
+
+static uint64_t bcm2835_dma_read(BCM2835DMAState *s, hwaddr offset,
+                                 unsigned size, unsigned c)
+{
+    BCM2835DMAChan *ch;
+    uint32_t res = 0;
+
+    assert(size == 4);
+    assert(c < BCM2835_DMA_NCHANS);
+
+    ch = &s->chan[c];
+
+    switch (offset) {
+    case BCM2708_DMA_CS:
+        res = ch->cs;
+        break;
+    case BCM2708_DMA_ADDR:
+        res = ch->conblk_ad;
+        break;
+    case BCM2708_DMA_INFO:
+        res = ch->ti;
+        break;
+    case BCM2708_DMA_SOURCE_AD:
+        res = ch->source_ad;
+        break;
+    case BCM2708_DMA_DEST_AD:
+        res = ch->dest_ad;
+        break;
+    case BCM2708_DMA_TXFR_LEN:
+        res = ch->txfr_len;
+        break;
+    case BCM2708_DMA_STRIDE:
+        res = ch->stride;
+        break;
+    case BCM2708_DMA_NEXTCB:
+        res = ch->nextconbk;
+        break;
+    case BCM2708_DMA_DEBUG:
+        res = ch->debug;
+        break;
+    default:
+        qemu_log_mask(LOG_GUEST_ERROR, "%s: Bad offset %"HWADDR_PRIx"\n",
+                      __func__, offset);
+        break;
+    }
+    return res;
+}
+
+static void bcm2835_dma_write(BCM2835DMAState *s, hwaddr offset,
+                              uint64_t value, unsigned size, unsigned c)
+{
+    BCM2835DMAChan *ch;
+    uint32_t oldcs;
+
+    assert(size == 4);
+    assert(c < BCM2835_DMA_NCHANS);
+
+    ch = &s->chan[c];
+
+    switch (offset) {
+    case BCM2708_DMA_CS:
+        oldcs = ch->cs;
+        if (value & BCM2708_DMA_RESET) {
+            bcm2835_dma_chan_reset(ch);
+        }
+        if (value & BCM2708_DMA_ABORT) {
+            /* abort is a no-op, since we always run to completion */
+        }
+        if (value & BCM2708_DMA_END) {
+            ch->cs &= ~BCM2708_DMA_END;
+        }
+        if (value & BCM2708_DMA_INT) {
+            ch->cs &= ~BCM2708_DMA_INT;
+            s->int_status &= ~(1 << c);
+            qemu_set_irq(ch->irq, 0);
+        }
+        ch->cs &= ~BCM2708_DMA_CS_RW_MASK;
+        ch->cs |= (value & BCM2708_DMA_CS_RW_MASK);
+        if (!(oldcs & BCM2708_DMA_ACTIVE) && (ch->cs & BCM2708_DMA_ACTIVE)) {
+            bcm2835_dma_update(s, c);
+        }
+        break;
+    case BCM2708_DMA_ADDR:
+        ch->conblk_ad = value;
+        break;
+    case BCM2708_DMA_DEBUG:
+        ch->debug = value;
+        break;
+    default:
+        qemu_log_mask(LOG_GUEST_ERROR, "%s: Bad offset %"HWADDR_PRIx"\n",
+                      __func__, offset);
+        break;
+    }
+}
+
+static uint64_t bcm2835_dma0_read(void *opaque, hwaddr offset, unsigned size)
+{
+    BCM2835DMAState *s = opaque;
+
+    if (offset < 0xf00) {
+        return bcm2835_dma_read(s, (offset & 0xff), size, (offset >> 8) & 0xf);
+    } else {
+        switch (offset) {
+        case BCM2708_DMA_INT_STATUS:
+            return s->int_status;
+        case BCM2708_DMA_ENABLE:
+            return s->enable;
+        default:
+            qemu_log_mask(LOG_GUEST_ERROR, "%s: Bad offset %"HWADDR_PRIx"\n",
+                          __func__, offset);
+            return 0;
+        }
+    }
+}
+
+static uint64_t bcm2835_dma15_read(void *opaque, hwaddr offset, unsigned size)
+{
+    return bcm2835_dma_read(opaque, (offset & 0xff), size, 15);
+}
+
+static void bcm2835_dma0_write(void *opaque, hwaddr offset, uint64_t value,
+                               unsigned size)
+{
+    BCM2835DMAState *s = opaque;
+
+    if (offset < 0xf00) {
+        bcm2835_dma_write(s, (offset & 0xff), value, size, (offset >> 8) & 0xf);
+    } else {
+        switch (offset) {
+        case BCM2708_DMA_INT_STATUS:
+            break;
+        case BCM2708_DMA_ENABLE:
+            s->enable = (value & 0xffff);
+            break;
+        default:
+            qemu_log_mask(LOG_GUEST_ERROR, "%s: Bad offset %"HWADDR_PRIx"\n",
+                          __func__, offset);
+        }
+    }
+
+}
+
+static void bcm2835_dma15_write(void *opaque, hwaddr offset, uint64_t value,
+                                unsigned size)
+{
+    bcm2835_dma_write(opaque, (offset & 0xff), value, size, 15);
+}
+
+static const MemoryRegionOps bcm2835_dma0_ops = {
+    .read = bcm2835_dma0_read,
+    .write = bcm2835_dma0_write,
+    .endianness = DEVICE_NATIVE_ENDIAN,
+    .valid.min_access_size = 4,
+    .valid.max_access_size = 4,
+};
+
+static const MemoryRegionOps bcm2835_dma15_ops = {
+    .read = bcm2835_dma15_read,
+    .write = bcm2835_dma15_write,
+    .endianness = DEVICE_NATIVE_ENDIAN,
+    .valid.min_access_size = 4,
+    .valid.max_access_size = 4,
+};
+
+static const VMStateDescription vmstate_bcm2835_dma_chan = {
+    .name = TYPE_BCM2835_DMA "-chan",
+    .version_id = 1,
+    .minimum_version_id = 1,
+    .fields = (VMStateField[]) {
+        VMSTATE_UINT32(cs, BCM2835DMAChan),
+        VMSTATE_UINT32(conblk_ad, BCM2835DMAChan),
+        VMSTATE_UINT32(ti, BCM2835DMAChan),
+        VMSTATE_UINT32(source_ad, BCM2835DMAChan),
+        VMSTATE_UINT32(dest_ad, BCM2835DMAChan),
+        VMSTATE_UINT32(txfr_len, BCM2835DMAChan),
+        VMSTATE_UINT32(stride, BCM2835DMAChan),
+        VMSTATE_UINT32(nextconbk, BCM2835DMAChan),
+        VMSTATE_UINT32(debug, BCM2835DMAChan),
+        VMSTATE_END_OF_LIST()
+    }
+};
+
+static const VMStateDescription vmstate_bcm2835_dma = {
+    .name = TYPE_BCM2835_DMA,
+    .version_id = 1,
+    .minimum_version_id = 1,
+    .fields = (VMStateField[]) {
+        VMSTATE_STRUCT_ARRAY(chan, BCM2835DMAState, BCM2835_DMA_NCHANS, 1,
+                             vmstate_bcm2835_dma_chan, BCM2835DMAChan),
+        VMSTATE_UINT32(int_status, BCM2835DMAState),
+        VMSTATE_UINT32(enable, BCM2835DMAState),
+        VMSTATE_END_OF_LIST()
+    }
+};
+
+static void bcm2835_dma_init(Object *obj)
+{
+    BCM2835DMAState *s = BCM2835_DMA(obj);
+    int n;
+
+    /* DMA channels 0-14 occupy a contiguous block of IO memory, along
+     * with the global enable and interrupt status bits. Channel 15
+     * has the same register map, but is mapped at a discontiguous
+     * address in a separate IO block.
+     */
+    memory_region_init_io(&s->iomem0, OBJECT(s), &bcm2835_dma0_ops, s,
+                          TYPE_BCM2835_DMA, 0x1000);
+    sysbus_init_mmio(SYS_BUS_DEVICE(s), &s->iomem0);
+
+    memory_region_init_io(&s->iomem15, OBJECT(s), &bcm2835_dma15_ops, s,
+                          TYPE_BCM2835_DMA "-chan15", 0x100);
+    sysbus_init_mmio(SYS_BUS_DEVICE(s), &s->iomem15);
+
+    for (n = 0; n < 16; n++) {
+        sysbus_init_irq(SYS_BUS_DEVICE(s), &s->chan[n].irq);
+    }
+}
+
+static void bcm2835_dma_reset(DeviceState *dev)
+{
+    BCM2835DMAState *s = BCM2835_DMA(dev);
+    int n;
+
+    s->enable = 0xffff;
+    s->int_status = 0;
+    for (n = 0; n < BCM2835_DMA_NCHANS; n++) {
+        bcm2835_dma_chan_reset(&s->chan[n]);
+    }
+}
+
+static void bcm2835_dma_realize(DeviceState *dev, Error **errp)
+{
+    BCM2835DMAState *s = BCM2835_DMA(dev);
+    Error *err = NULL;
+    Object *obj;
+
+    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);
+
+    bcm2835_dma_reset(dev);
+}
+
+static void bcm2835_dma_class_init(ObjectClass *klass, void *data)
+{
+    DeviceClass *dc = DEVICE_CLASS(klass);
+
+    dc->realize = bcm2835_dma_realize;
+    dc->reset = bcm2835_dma_reset;
+    dc->vmsd = &vmstate_bcm2835_dma;
+}
+
+static TypeInfo bcm2835_dma_info = {
+    .name          = TYPE_BCM2835_DMA,
+    .parent        = TYPE_SYS_BUS_DEVICE,
+    .instance_size = sizeof(BCM2835DMAState),
+    .class_init    = bcm2835_dma_class_init,
+    .instance_init = bcm2835_dma_init,
+};
+
+static void bcm2835_dma_register_types(void)
+{
+    type_register_static(&bcm2835_dma_info);
+}
+
+type_init(bcm2835_dma_register_types)
diff --git a/include/hw/arm/bcm2835_peripherals.h b/include/hw/arm/bcm2835_peripherals.h
index e19d360..e12ae37 100644
--- a/include/hw/arm/bcm2835_peripherals.h
+++ b/include/hw/arm/bcm2835_peripherals.h
@@ -16,6 +16,7 @@ 
 #include "hw/sysbus.h"
 #include "hw/char/bcm2835_aux.h"
 #include "hw/display/bcm2835_fb.h"
+#include "hw/dma/bcm2835_dma.h"
 #include "hw/intc/bcm2835_ic.h"
 #include "hw/misc/bcm2835_property.h"
 #include "hw/misc/bcm2835_mbox.h"
@@ -37,6 +38,7 @@  typedef struct BCM2835PeripheralState {
     SysBusDevice *uart0;
     BCM2835AuxState aux;
     BCM2835FBState fb;
+    BCM2835DMAState dma;
     BCM2835ICState ic;
     BCM2835PropertyState property;
     BCM2835MboxState mboxes;
diff --git a/include/hw/dma/bcm2835_dma.h b/include/hw/dma/bcm2835_dma.h
new file mode 100644
index 0000000..75312e2
--- /dev/null
+++ b/include/hw/dma/bcm2835_dma.h
@@ -0,0 +1,47 @@ 
+/*
+ * Raspberry Pi emulation (c) 2012 Gregory Estrade
+ * This code is licensed under the GNU GPLv2 and later.
+ */
+
+#ifndef BCM2835_DMA_H
+#define BCM2835_DMA_H
+
+#include "qemu-common.h"
+#include "exec/address-spaces.h"
+#include "hw/sysbus.h"
+
+typedef struct {
+    uint32_t cs;
+    uint32_t conblk_ad;
+    uint32_t ti;
+    uint32_t source_ad;
+    uint32_t dest_ad;
+    uint32_t txfr_len;
+    uint32_t stride;
+    uint32_t nextconbk;
+    uint32_t debug;
+
+    qemu_irq irq;
+} BCM2835DMAChan;
+
+#define TYPE_BCM2835_DMA "bcm2835-dma"
+#define BCM2835_DMA(obj) \
+        OBJECT_CHECK(BCM2835DMAState, (obj), TYPE_BCM2835_DMA)
+
+#define BCM2835_DMA_NCHANS 16
+
+typedef struct {
+    /*< private >*/
+    SysBusDevice busdev;
+    /*< public >*/
+
+    MemoryRegion iomem0, iomem15;
+    MemoryRegion *dma_mr;
+    AddressSpace dma_as;
+
+    BCM2835DMAChan chan[BCM2835_DMA_NCHANS];
+    uint32_t int_status;
+    uint32_t enable;
+} BCM2835DMAState;
+
+#endif