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>

1 files changed, 15 insertions, 0 deletions

diff --git a/hw/arm/bcm2835_peripherals.c b/hw/arm/bcm2835_peripherals.c
index 2e641a3989..9ed22d5bc8 100644
--- a/hw/arm/bcm2835_peripherals.c
+++ b/hw/arm/bcm2835_peripherals.c
@@ -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);