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, 27 insertions, 0 deletions

diff --git a/include/hw/misc/bcm2835_rng.h b/include/hw/misc/bcm2835_rng.h
new file mode 100644
index 0000000000..41a531bce7
--- /dev/null
+++ b/include/hw/misc/bcm2835_rng.h
@@ -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