Commit 54a5ba13 authored by Marcin Chojnacki's avatar Marcin Chojnacki Committed by Peter Maydell
Browse files

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: default avatarMarcin Chojnacki <marcinch7@gmail.com>
Message-id: 20170210210857.47893-1-marcinch7@gmail.com
Reviewed-by: default avatarPeter Maydell <peter.maydell@linaro.org>
Signed-off-by: default avatarPeter Maydell <peter.maydell@linaro.org>
parent 6181478f

hw/arm/bcm2835_peripherals.c

+15 −0
Original line number Diff line number Diff line
@@ -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);

hw/misc/Makefile.objs

+1 −0
Original line number Diff line number Diff line
@@ -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

hw/misc/bcm2835_rng.c

0 → 100644
+124 −0
Original line number Diff line number Diff line 
/*

 * 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)

include/hw/arm/bcm2835_peripherals.h

+2 −0
Original line number Diff line number Diff line
@@ -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;

include/hw/misc/bcm2835_rng.h

0 → 100644
+27 −0
Original line number Diff line number Diff line 
/*

 * 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