target-arm: Implement BCM2835 hardware RNG

Recent vanilla Raspberry Pi kernels started to make use of
the hardware random number generator in BCM2835 SoC. As a
result, those kernels wouldn't work anymore under QEMU
but rather just freeze during the boot process.

This patch implements a trivial BCM2835 compatible RNG,
and adds it as a peripheral to BCM2835 platform, which
allows to boot a vanilla Raspberry Pi kernel under Qemu.

Changes since v1:
 * Prevented guest from writing [31..20] bits in rng_status
 * Removed redundant minimum_version_id_old
 * Added field entries for the state
 * Changed realize function to reset

Signed-off-by: Marcin Chojnacki <marcinch7@gmail.com>
Message-id: 20170210210857.47893-1-marcinch7@gmail.com
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
This commit is contained in:
Marcin Chojnacki 2017-02-28 12:08:13 +00:00 committed by Peter Maydell
parent 6181478f63
commit 54a5ba13a9
5 changed files with 169 additions and 0 deletions

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@ -86,6 +86,11 @@ static void bcm2835_peripherals_init(Object *obj)
object_property_add_const_link(OBJECT(&s->property), "dma-mr",
OBJECT(&s->gpu_bus_mr), &error_abort);
/* Random Number Generator */
object_initialize(&s->rng, sizeof(s->rng), TYPE_BCM2835_RNG);
object_property_add_child(obj, "rng", OBJECT(&s->rng), NULL);
qdev_set_parent_bus(DEVICE(&s->rng), sysbus_get_default());
/* Extended Mass Media Controller */
object_initialize(&s->sdhci, sizeof(s->sdhci), TYPE_SYSBUS_SDHCI);
object_property_add_child(obj, "sdhci", OBJECT(&s->sdhci), NULL);
@ -226,6 +231,16 @@ static void bcm2835_peripherals_realize(DeviceState *dev, Error **errp)
sysbus_connect_irq(SYS_BUS_DEVICE(&s->property), 0,
qdev_get_gpio_in(DEVICE(&s->mboxes), MBOX_CHAN_PROPERTY));
/* Random Number Generator */
object_property_set_bool(OBJECT(&s->rng), true, "realized", &err);
if (err) {
error_propagate(errp, err);
return;
}
memory_region_add_subregion(&s->peri_mr, RNG_OFFSET,
sysbus_mmio_get_region(SYS_BUS_DEVICE(&s->rng), 0));
/* Extended Mass Media Controller */
object_property_set_int(OBJECT(&s->sdhci), BCM2835_SDHC_CAPAREG, "capareg",
&err);

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@ -42,6 +42,7 @@ 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-$(CONFIG_RASPI) += bcm2835_rng.o
obj-$(CONFIG_SLAVIO) += slavio_misc.o
obj-$(CONFIG_ZYNQ) += zynq_slcr.o
obj-$(CONFIG_ZYNQ) += zynq-xadc.o

124
hw/misc/bcm2835_rng.c Normal file
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@ -0,0 +1,124 @@
/*
* BCM2835 Random Number Generator emulation
*
* Copyright (C) 2017 Marcin Chojnacki <marcinch7@gmail.com>
*
* This work is licensed under the terms of the GNU GPL, version 2 or later.
* See the COPYING file in the top-level directory.
*/
#include "qemu/osdep.h"
#include "qemu/log.h"
#include "hw/misc/bcm2835_rng.h"
static uint64_t bcm2835_rng_read(void *opaque, hwaddr offset,
unsigned size)
{
BCM2835RngState *s = (BCM2835RngState *)opaque;
uint32_t res = 0;
assert(size == 4);
switch (offset) {
case 0x0: /* rng_ctrl */
res = s->rng_ctrl;
break;
case 0x4: /* rng_status */
res = s->rng_status | (1 << 24);
break;
case 0x8: /* rng_data */
res = rand();
break;
default:
qemu_log_mask(LOG_GUEST_ERROR,
"bcm2835_rng_read: Bad offset %x\n",
(int)offset);
res = 0;
break;
}
return res;
}
static void bcm2835_rng_write(void *opaque, hwaddr offset,
uint64_t value, unsigned size)
{
BCM2835RngState *s = (BCM2835RngState *)opaque;
assert(size == 4);
switch (offset) {
case 0x0: /* rng_ctrl */
s->rng_ctrl = value;
break;
case 0x4: /* rng_status */
/* we shouldn't let the guest write to bits [31..20] */
s->rng_status &= ~0xFFFFF; /* clear 20 lower bits */
s->rng_status |= value & 0xFFFFF; /* set them to new value */
break;
default:
qemu_log_mask(LOG_GUEST_ERROR,
"bcm2835_rng_write: Bad offset %x\n",
(int)offset);
break;
}
}
static const MemoryRegionOps bcm2835_rng_ops = {
.read = bcm2835_rng_read,
.write = bcm2835_rng_write,
.endianness = DEVICE_NATIVE_ENDIAN,
};
static const VMStateDescription vmstate_bcm2835_rng = {
.name = TYPE_BCM2835_RNG,
.version_id = 1,
.minimum_version_id = 1,
.fields = (VMStateField[]) {
VMSTATE_UINT32(rng_ctrl, BCM2835RngState),
VMSTATE_UINT32(rng_status, BCM2835RngState),
VMSTATE_END_OF_LIST()
}
};
static void bcm2835_rng_init(Object *obj)
{
BCM2835RngState *s = BCM2835_RNG(obj);
memory_region_init_io(&s->iomem, obj, &bcm2835_rng_ops, s,
TYPE_BCM2835_RNG, 0x10);
sysbus_init_mmio(SYS_BUS_DEVICE(s), &s->iomem);
}
static void bcm2835_rng_reset(DeviceState *dev)
{
BCM2835RngState *s = BCM2835_RNG(dev);
s->rng_ctrl = 0;
s->rng_status = 0;
}
static void bcm2835_rng_class_init(ObjectClass *klass, void *data)
{
DeviceClass *dc = DEVICE_CLASS(klass);
dc->reset = bcm2835_rng_reset;
dc->vmsd = &vmstate_bcm2835_rng;
}
static TypeInfo bcm2835_rng_info = {
.name = TYPE_BCM2835_RNG,
.parent = TYPE_SYS_BUS_DEVICE,
.instance_size = sizeof(BCM2835RngState),
.class_init = bcm2835_rng_class_init,
.instance_init = bcm2835_rng_init,
};
static void bcm2835_rng_register_types(void)
{
type_register_static(&bcm2835_rng_info);
}
type_init(bcm2835_rng_register_types)

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@ -19,6 +19,7 @@
#include "hw/dma/bcm2835_dma.h"
#include "hw/intc/bcm2835_ic.h"
#include "hw/misc/bcm2835_property.h"
#include "hw/misc/bcm2835_rng.h"
#include "hw/misc/bcm2835_mbox.h"
#include "hw/sd/sdhci.h"
@ -41,6 +42,7 @@ typedef struct BCM2835PeripheralState {
BCM2835DMAState dma;
BCM2835ICState ic;
BCM2835PropertyState property;
BCM2835RngState rng;
BCM2835MboxState mboxes;
SDHCIState sdhci;
} BCM2835PeripheralState;

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@ -0,0 +1,27 @@
/*
* BCM2835 Random Number Generator emulation
*
* Copyright (C) 2017 Marcin Chojnacki <marcinch7@gmail.com>
*
* This work is licensed under the terms of the GNU GPL, version 2 or later.
* See the COPYING file in the top-level directory.
*/
#ifndef BCM2835_RNG_H
#define BCM2835_RNG_H
#include "hw/sysbus.h"
#define TYPE_BCM2835_RNG "bcm2835-rng"
#define BCM2835_RNG(obj) \
OBJECT_CHECK(BCM2835RngState, (obj), TYPE_BCM2835_RNG)
typedef struct {
SysBusDevice busdev;
MemoryRegion iomem;
uint32_t rng_ctrl;
uint32_t rng_status;
} BCM2835RngState;
#endif