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From: Peter Maydell <peter.maydell@linaro.org>
To: qemu-devel@nongnu.org
Subject: [PULL 17/48] hw/misc: Add npcm7xx random number generator
Date: Tue, 27 Oct 2020 11:44:07 +0000
Message-Id: <20201027114438.17662-18-peter.maydell@linaro.org>
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Content-Type: text/plain; charset="utf-8"

From: Havard Skinnemoen <hskinnemoen@google.com>

The RNG module returns a byte of randomness when the Data Valid bit is
set.

This implementation ignores the prescaler setting, and loads a new value
into RNGD every time RNGCS is read while the RNG is enabled and random
data is available.

A qtest featuring some simple randomness tests is included.

Reviewed-by: Tyrone Ting <kfting@nuvoton.com>
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Havard Skinnemoen <hskinnemoen@google.com>
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
---
 docs/system/arm/nuvoton.rst    |   2 +-
 include/hw/arm/npcm7xx.h       |   2 +
 include/hw/misc/npcm7xx_rng.h  |  34 ++++
 hw/arm/npcm7xx.c               |   7 +-
 hw/misc/npcm7xx_rng.c          | 180 +++++++++++++++++++++
 tests/qtest/npcm7xx_rng-test.c | 278 +++++++++++++++++++++++++++++++++
 hw/misc/meson.build            |   1 +
 hw/misc/trace-events           |   4 +
 tests/qtest/meson.build        |   5 +-
 9 files changed, 510 insertions(+), 3 deletions(-)
 create mode 100644 include/hw/misc/npcm7xx_rng.h
 create mode 100644 hw/misc/npcm7xx_rng.c
 create mode 100644 tests/qtest/npcm7xx_rng-test.c

diff --git a/docs/system/arm/nuvoton.rst b/docs/system/arm/nuvoton.rst
index e3e1a3a3a73..4342434df4a 100644
--- a/docs/system/arm/nuvoton.rst
+++ b/docs/system/arm/nuvoton.rst
@@ -38,6 +38,7 @@ Supported devices
  * DDR4 memory controller (dummy interface indicating memory training is d=
one)
  * OTP controllers (no protection features)
  * Flash Interface Unit (FIU; no protection features)
+ * Random Number Generator (RNG)
=20
 Missing devices
 ---------------
@@ -59,7 +60,6 @@ Missing devices
  * Peripheral SPI controller (PSPI)
  * Analog to Digital Converter (ADC)
  * SD/MMC host
- * Random Number Generator (RNG)
  * PECI interface
  * Pulse Width Modulation (PWM)
  * Tachometer
diff --git a/include/hw/arm/npcm7xx.h b/include/hw/arm/npcm7xx.h
index 13106af2151..761f9b987ed 100644
--- a/include/hw/arm/npcm7xx.h
+++ b/include/hw/arm/npcm7xx.h
@@ -21,6 +21,7 @@
 #include "hw/mem/npcm7xx_mc.h"
 #include "hw/misc/npcm7xx_clk.h"
 #include "hw/misc/npcm7xx_gcr.h"
+#include "hw/misc/npcm7xx_rng.h"
 #include "hw/nvram/npcm7xx_otp.h"
 #include "hw/timer/npcm7xx_timer.h"
 #include "hw/ssi/npcm7xx_fiu.h"
@@ -75,6 +76,7 @@ typedef struct NPCM7xxState {
     NPCM7xxOTPState     key_storage;
     NPCM7xxOTPState     fuse_array;
     NPCM7xxMCState      mc;
+    NPCM7xxRNGState     rng;
     NPCM7xxFIUState     fiu[2];
 } NPCM7xxState;
=20
diff --git a/include/hw/misc/npcm7xx_rng.h b/include/hw/misc/npcm7xx_rng.h
new file mode 100644
index 00000000000..5e85fd439d8
--- /dev/null
+++ b/include/hw/misc/npcm7xx_rng.h
@@ -0,0 +1,34 @@
+/*
+ * Nuvoton NPCM7xx Random Number Generator.
+ *
+ * Copyright 2020 Google LLC
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License as published by the
+ * Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful, but WIT=
HOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
+ * for more details.
+ */
+#ifndef NPCM7XX_RNG_H
+#define NPCM7XX_RNG_H
+
+#include "hw/sysbus.h"
+
+typedef struct NPCM7xxRNGState {
+    SysBusDevice parent;
+
+    MemoryRegion iomem;
+
+    uint8_t rngcs;
+    uint8_t rngd;
+    uint8_t rngmode;
+} NPCM7xxRNGState;
+
+#define TYPE_NPCM7XX_RNG "npcm7xx-rng"
+#define NPCM7XX_RNG(obj) OBJECT_CHECK(NPCM7xxRNGState, (obj), TYPE_NPCM7XX=
_RNG)
+
+#endif /* NPCM7XX_RNG_H */
diff --git a/hw/arm/npcm7xx.c b/hw/arm/npcm7xx.c
index c341dcab8b3..cb4db41c542 100644
--- a/hw/arm/npcm7xx.c
+++ b/hw/arm/npcm7xx.c
@@ -44,6 +44,7 @@
 #define NPCM7XX_GCR_BA          (0xf0800000)
 #define NPCM7XX_CLK_BA          (0xf0801000)
 #define NPCM7XX_MC_BA           (0xf0824000)
+#define NPCM7XX_RNG_BA          (0xf000b000)
=20
 /* Internal AHB SRAM */
 #define NPCM7XX_RAM3_BA         (0xc0008000)
@@ -256,6 +257,7 @@ static void npcm7xx_init(Object *obj)
     object_initialize_child(obj, "otp2", &s->fuse_array,
                             TYPE_NPCM7XX_FUSE_ARRAY);
     object_initialize_child(obj, "mc", &s->mc, TYPE_NPCM7XX_MC);
+    object_initialize_child(obj, "rng", &s->rng, TYPE_NPCM7XX_RNG);
=20
     for (i =3D 0; i < ARRAY_SIZE(s->tim); i++) {
         object_initialize_child(obj, "tim[*]", &s->tim[i], TYPE_NPCM7XX_TI=
MER);
@@ -374,6 +376,10 @@ static void npcm7xx_realize(DeviceState *dev, Error **=
errp)
                        serial_hd(i), DEVICE_LITTLE_ENDIAN);
     }
=20
+    /* Random Number Generator. Cannot fail. */
+    sysbus_realize(SYS_BUS_DEVICE(&s->rng), &error_abort);
+    sysbus_mmio_map(SYS_BUS_DEVICE(&s->rng), 0, NPCM7XX_RNG_BA);
+
     /*
      * Flash Interface Unit (FIU). Can fail if incorrect number of chip se=
lects
      * specified, but this is a programming error.
@@ -412,7 +418,6 @@ static void npcm7xx_realize(DeviceState *dev, Error **e=
rrp)
     create_unimplemented_device("npcm7xx.vdmx",         0xe0800000,   4 * =
KiB);
     create_unimplemented_device("npcm7xx.pcierc",       0xe1000000,  64 * =
KiB);
     create_unimplemented_device("npcm7xx.kcs",          0xf0007000,   4 * =
KiB);
-    create_unimplemented_device("npcm7xx.rng",          0xf000b000,   4 * =
KiB);
     create_unimplemented_device("npcm7xx.adc",          0xf000c000,   4 * =
KiB);
     create_unimplemented_device("npcm7xx.gfxi",         0xf000e000,   4 * =
KiB);
     create_unimplemented_device("npcm7xx.gpio[0]",      0xf0010000,   4 * =
KiB);
diff --git a/hw/misc/npcm7xx_rng.c b/hw/misc/npcm7xx_rng.c
new file mode 100644
index 00000000000..f650f3401f8
--- /dev/null
+++ b/hw/misc/npcm7xx_rng.c
@@ -0,0 +1,180 @@
+/*
+ * Nuvoton NPCM7xx Random Number Generator.
+ *
+ * Copyright 2020 Google LLC
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License as published by the
+ * Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful, but WIT=
HOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
+ * for more details.
+ */
+
+#include "qemu/osdep.h"
+
+#include "hw/misc/npcm7xx_rng.h"
+#include "migration/vmstate.h"
+#include "qemu/bitops.h"
+#include "qemu/guest-random.h"
+#include "qemu/log.h"
+#include "qemu/module.h"
+#include "qemu/units.h"
+
+#include "trace.h"
+
+#define NPCM7XX_RNG_REGS_SIZE   (4 * KiB)
+
+#define NPCM7XX_RNGCS           (0x00)
+#define NPCM7XX_RNGCS_CLKP(rv)      extract32(rv, 2, 4)
+#define NPCM7XX_RNGCS_DVALID        BIT(1)
+#define NPCM7XX_RNGCS_RNGE          BIT(0)
+
+#define NPCM7XX_RNGD            (0x04)
+#define NPCM7XX_RNGMODE         (0x08)
+#define NPCM7XX_RNGMODE_NORMAL      (0x02)
+
+static bool npcm7xx_rng_is_enabled(NPCM7xxRNGState *s)
+{
+    return (s->rngcs & NPCM7XX_RNGCS_RNGE) &&
+        (s->rngmode =3D=3D NPCM7XX_RNGMODE_NORMAL);
+}
+
+static uint64_t npcm7xx_rng_read(void *opaque, hwaddr offset, unsigned siz=
e)
+{
+    NPCM7xxRNGState *s =3D opaque;
+    uint64_t value =3D 0;
+
+    switch (offset) {
+    case NPCM7XX_RNGCS:
+        /*
+         * If the RNG is enabled, but we don't have any valid random data,=
 try
+         * obtaining some and update the DVALID bit accordingly.
+         */
+        if (!npcm7xx_rng_is_enabled(s)) {
+            s->rngcs &=3D ~NPCM7XX_RNGCS_DVALID;
+        } else if (!(s->rngcs & NPCM7XX_RNGCS_DVALID)) {
+            uint8_t byte =3D 0;
+
+            if (qemu_guest_getrandom(&byte, sizeof(byte), NULL) =3D=3D 0) {
+                s->rngd =3D byte;
+                s->rngcs |=3D NPCM7XX_RNGCS_DVALID;
+            }
+        }
+        value =3D s->rngcs;
+        break;
+    case NPCM7XX_RNGD:
+        if (npcm7xx_rng_is_enabled(s) && s->rngcs & NPCM7XX_RNGCS_DVALID) {
+            s->rngcs &=3D ~NPCM7XX_RNGCS_DVALID;
+            value =3D s->rngd;
+            s->rngd =3D 0;
+        }
+        break;
+    case NPCM7XX_RNGMODE:
+        value =3D s->rngmode;
+        break;
+
+    default:
+        qemu_log_mask(LOG_GUEST_ERROR,
+                      "%s: read from invalid offset 0x%" HWADDR_PRIx "\n",
+                      DEVICE(s)->canonical_path, offset);
+        break;
+    }
+
+    trace_npcm7xx_rng_read(offset, value, size);
+
+    return value;
+}
+
+static void npcm7xx_rng_write(void *opaque, hwaddr offset, uint64_t value,
+                              unsigned size)
+{
+    NPCM7xxRNGState *s =3D opaque;
+
+    trace_npcm7xx_rng_write(offset, value, size);
+
+    switch (offset) {
+    case NPCM7XX_RNGCS:
+        s->rngcs &=3D NPCM7XX_RNGCS_DVALID;
+        s->rngcs |=3D value & ~NPCM7XX_RNGCS_DVALID;
+        break;
+    case NPCM7XX_RNGD:
+        qemu_log_mask(LOG_GUEST_ERROR,
+                      "%s: write to read-only register @ 0x%" HWADDR_PRIx =
"\n",
+                      DEVICE(s)->canonical_path, offset);
+        break;
+    case NPCM7XX_RNGMODE:
+        s->rngmode =3D value;
+        break;
+    default:
+        qemu_log_mask(LOG_GUEST_ERROR,
+                      "%s: write to invalid offset 0x%" HWADDR_PRIx "\n",
+                      DEVICE(s)->canonical_path, offset);
+        break;
+    }
+}
+
+static const MemoryRegionOps npcm7xx_rng_ops =3D {
+    .read =3D npcm7xx_rng_read,
+    .write =3D npcm7xx_rng_write,
+    .endianness =3D DEVICE_LITTLE_ENDIAN,
+    .valid =3D {
+        .min_access_size =3D 1,
+        .max_access_size =3D 4,
+        .unaligned =3D false,
+    },
+};
+
+static void npcm7xx_rng_enter_reset(Object *obj, ResetType type)
+{
+    NPCM7xxRNGState *s =3D NPCM7XX_RNG(obj);
+
+    s->rngcs =3D 0;
+    s->rngd =3D 0;
+    s->rngmode =3D 0;
+}
+
+static void npcm7xx_rng_init(Object *obj)
+{
+    NPCM7xxRNGState *s =3D NPCM7XX_RNG(obj);
+
+    memory_region_init_io(&s->iomem, obj, &npcm7xx_rng_ops, s, "regs",
+                          NPCM7XX_RNG_REGS_SIZE);
+    sysbus_init_mmio(&s->parent, &s->iomem);
+}
+
+static const VMStateDescription vmstate_npcm7xx_rng =3D {
+    .name =3D "npcm7xx-rng",
+    .version_id =3D 0,
+    .minimum_version_id =3D 0,
+    .fields =3D (VMStateField[]) {
+        VMSTATE_UINT8(rngcs, NPCM7xxRNGState),
+        VMSTATE_UINT8(rngd, NPCM7xxRNGState),
+        VMSTATE_UINT8(rngmode, NPCM7xxRNGState),
+        VMSTATE_END_OF_LIST(),
+    },
+};
+
+static void npcm7xx_rng_class_init(ObjectClass *klass, void *data)
+{
+    ResettableClass *rc =3D RESETTABLE_CLASS(klass);
+    DeviceClass *dc =3D DEVICE_CLASS(klass);
+
+    dc->desc =3D "NPCM7xx Random Number Generator";
+    dc->vmsd =3D &vmstate_npcm7xx_rng;
+    rc->phases.enter =3D npcm7xx_rng_enter_reset;
+}
+
+static const TypeInfo npcm7xx_rng_types[] =3D {
+    {
+        .name =3D TYPE_NPCM7XX_RNG,
+        .parent =3D TYPE_SYS_BUS_DEVICE,
+        .instance_size =3D sizeof(NPCM7xxRNGState),
+        .class_init =3D npcm7xx_rng_class_init,
+        .instance_init =3D npcm7xx_rng_init,
+    },
+};
+DEFINE_TYPES(npcm7xx_rng_types);
diff --git a/tests/qtest/npcm7xx_rng-test.c b/tests/qtest/npcm7xx_rng-test.c
new file mode 100644
index 00000000000..da6e639bf6f
--- /dev/null
+++ b/tests/qtest/npcm7xx_rng-test.c
@@ -0,0 +1,278 @@
+/*
+ * QTest testcase for the Nuvoton NPCM7xx Random Number Generator
+ *
+ * Copyright 2020 Google LLC
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License as published by the
+ * Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful, but WIT=
HOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
+ * for more details.
+ */
+
+#include "qemu/osdep.h"
+
+#include <math.h>
+
+#include "libqtest-single.h"
+#include "qemu/bitops.h"
+
+#define RNG_BASE_ADDR   0xf000b000
+
+/* Control and Status Register */
+#define RNGCS   0x00
+# define DVALID     BIT(1)  /* Data Valid */
+# define RNGE       BIT(0)  /* RNG Enable */
+/* Data Register */
+#define RNGD    0x04
+/* Mode Register */
+#define RNGMODE 0x08
+# define ROSEL_NORMAL   (2) /* RNG only works in this mode */
+
+/* Number of bits to collect for randomness tests. */
+#define TEST_INPUT_BITS  (128)
+
+static void rng_writeb(unsigned int offset, uint8_t value)
+{
+    writeb(RNG_BASE_ADDR + offset, value);
+}
+
+static uint8_t rng_readb(unsigned int offset)
+{
+    return readb(RNG_BASE_ADDR + offset);
+}
+
+/* Disable RNG and set normal ring oscillator mode. */
+static void rng_reset(void)
+{
+    rng_writeb(RNGCS, 0);
+    rng_writeb(RNGMODE, ROSEL_NORMAL);
+}
+
+/* Reset RNG and then enable it. */
+static void rng_reset_enable(void)
+{
+    rng_reset();
+    rng_writeb(RNGCS, RNGE);
+}
+
+/* Wait until Data Valid bit is set. */
+static bool rng_wait_ready(void)
+{
+    /* qemu_guest_getrandom may fail. Assume it won't fail 10 times in a r=
ow. */
+    int retries =3D 10;
+
+    while (retries-- > 0) {
+        if (rng_readb(RNGCS) & DVALID) {
+            return true;
+        }
+    }
+
+    return false;
+}
+
+/*
+ * Perform a frequency (monobit) test, as defined by NIST SP 800-22, on the
+ * sequence in buf and return the P-value. This represents the probability=
 of a
+ * truly random sequence having the same proportion of zeros and ones as t=
he
+ * sequence in buf.
+ *
+ * An RNG which always returns 0x00 or 0xff, or has some bits stuck at 0 o=
r 1,
+ * will fail this test. However, an RNG which always returns 0x55, 0xf0 or=
 some
+ * other value with an equal number of zeroes and ones will pass.
+ */
+static double calc_monobit_p(const uint8_t *buf, unsigned int len)
+{
+    unsigned int i;
+    double s_obs;
+    int sn =3D 0;
+
+    for (i =3D 0; i < len; i++) {
+        /*
+         * Each 1 counts as 1, each 0 counts as -1.
+         * s =3D cp - (8 - cp) =3D 2 * cp - 8
+         */
+        sn +=3D 2 * ctpop8(buf[i]) - 8;
+    }
+
+    s_obs =3D abs(sn) / sqrt(len * BITS_PER_BYTE);
+
+    return erfc(s_obs / sqrt(2));
+}
+
+/*
+ * Perform a runs test, as defined by NIST SP 800-22, and return the P-val=
ue.
+ * This represents the probability of a truly random sequence having the s=
ame
+ * number of runs (i.e. uninterrupted sequences of identical bits) as the
+ * sequence in buf.
+ */
+static double calc_runs_p(const unsigned long *buf, unsigned int nr_bits)
+{
+    unsigned int j;
+    unsigned int k;
+    int nr_ones =3D 0;
+    int vn_obs =3D 0;
+    double pi;
+
+    g_assert(nr_bits % BITS_PER_LONG =3D=3D 0);
+
+    for (j =3D 0; j < nr_bits / BITS_PER_LONG; j++) {
+        nr_ones +=3D __builtin_popcountl(buf[j]);
+    }
+    pi =3D (double)nr_ones / nr_bits;
+
+    for (k =3D 0; k < nr_bits - 1; k++) {
+        vn_obs +=3D !(test_bit(k, buf) ^ test_bit(k + 1, buf));
+    }
+    vn_obs +=3D 1;
+
+    return erfc(fabs(vn_obs - 2 * nr_bits * pi * (1.0 - pi))
+                / (2 * sqrt(2 * nr_bits) * pi * (1.0 - pi)));
+}
+
+/*
+ * Verifies that DVALID is clear, and RNGD reads zero, when RNGE is cleare=
d,
+ * and DVALID eventually becomes set when RNGE is set.
+ */
+static void test_enable_disable(void)
+{
+    /* Disable: DVALID should not be set, and RNGD should read zero */
+    rng_reset();
+    g_assert_cmphex(rng_readb(RNGCS), =3D=3D, 0);
+    g_assert_cmphex(rng_readb(RNGD), =3D=3D, 0);
+
+    /* Enable: DVALID should be set, but we can't make assumptions about R=
NGD */
+    rng_writeb(RNGCS, RNGE);
+    g_assert_true(rng_wait_ready());
+    g_assert_cmphex(rng_readb(RNGCS), =3D=3D, DVALID | RNGE);
+
+    /* Disable: DVALID should not be set, and RNGD should read zero */
+    rng_writeb(RNGCS, 0);
+    g_assert_cmphex(rng_readb(RNGCS), =3D=3D, 0);
+    g_assert_cmphex(rng_readb(RNGD), =3D=3D, 0);
+}
+
+/*
+ * Verifies that the RNG only produces data when RNGMODE is set to 'normal'
+ * ring oscillator mode.
+ */
+static void test_rosel(void)
+{
+    rng_reset_enable();
+    g_assert_true(rng_wait_ready());
+    rng_writeb(RNGMODE, 0);
+    g_assert_false(rng_wait_ready());
+    rng_writeb(RNGMODE, ROSEL_NORMAL);
+    g_assert_true(rng_wait_ready());
+    rng_writeb(RNGMODE, 0);
+    g_assert_false(rng_wait_ready());
+}
+
+/*
+ * Verifies that a continuous sequence of bits collected after enabling th=
e RNG
+ * satisfies a monobit test.
+ */
+static void test_continuous_monobit(void)
+{
+    uint8_t buf[TEST_INPUT_BITS / BITS_PER_BYTE];
+    unsigned int i;
+
+    rng_reset_enable();
+    for (i =3D 0; i < sizeof(buf); i++) {
+        g_assert_true(rng_wait_ready());
+        buf[i] =3D rng_readb(RNGD);
+    }
+
+    g_assert_cmpfloat(calc_monobit_p(buf, sizeof(buf)), >, 0.01);
+}
+
+/*
+ * Verifies that a continuous sequence of bits collected after enabling th=
e RNG
+ * satisfies a runs test.
+ */
+static void test_continuous_runs(void)
+{
+    union {
+        unsigned long l[TEST_INPUT_BITS / BITS_PER_LONG];
+        uint8_t c[TEST_INPUT_BITS / BITS_PER_BYTE];
+    } buf;
+    unsigned int i;
+
+    rng_reset_enable();
+    for (i =3D 0; i < sizeof(buf); i++) {
+        g_assert_true(rng_wait_ready());
+        buf.c[i] =3D rng_readb(RNGD);
+    }
+
+    g_assert_cmpfloat(calc_runs_p(buf.l, sizeof(buf) * BITS_PER_BYTE), >, =
0.01);
+}
+
+/*
+ * Verifies that the first data byte collected after enabling the RNG sati=
sfies
+ * a monobit test.
+ */
+static void test_first_byte_monobit(void)
+{
+    /* Enable, collect one byte, disable. Repeat until we have 100 bits. */
+    uint8_t buf[TEST_INPUT_BITS / BITS_PER_BYTE];
+    unsigned int i;
+
+    rng_reset();
+    for (i =3D 0; i < sizeof(buf); i++) {
+        rng_writeb(RNGCS, RNGE);
+        g_assert_true(rng_wait_ready());
+        buf[i] =3D rng_readb(RNGD);
+        rng_writeb(RNGCS, 0);
+    }
+
+    g_assert_cmpfloat(calc_monobit_p(buf, sizeof(buf)), >, 0.01);
+}
+
+/*
+ * Verifies that the first data byte collected after enabling the RNG sati=
sfies
+ * a runs test.
+ */
+static void test_first_byte_runs(void)
+{
+    /* Enable, collect one byte, disable. Repeat until we have 100 bits. */
+    union {
+        unsigned long l[TEST_INPUT_BITS / BITS_PER_LONG];
+        uint8_t c[TEST_INPUT_BITS / BITS_PER_BYTE];
+    } buf;
+    unsigned int i;
+
+    rng_reset();
+    for (i =3D 0; i < sizeof(buf); i++) {
+        rng_writeb(RNGCS, RNGE);
+        g_assert_true(rng_wait_ready());
+        buf.c[i] =3D rng_readb(RNGD);
+        rng_writeb(RNGCS, 0);
+    }
+
+    g_assert_cmpfloat(calc_runs_p(buf.l, sizeof(buf) * BITS_PER_BYTE), >, =
0.01);
+}
+
+int main(int argc, char **argv)
+{
+    int ret;
+
+    g_test_init(&argc, &argv, NULL);
+    g_test_set_nonfatal_assertions();
+
+    qtest_add_func("npcm7xx_rng/enable_disable", test_enable_disable);
+    qtest_add_func("npcm7xx_rng/rosel", test_rosel);
+    qtest_add_func("npcm7xx_rng/continuous/monobit", test_continuous_monob=
it);
+    qtest_add_func("npcm7xx_rng/continuous/runs", test_continuous_runs);
+    qtest_add_func("npcm7xx_rng/first_byte/monobit", test_first_byte_monob=
it);
+    qtest_add_func("npcm7xx_rng/first_byte/runs", test_first_byte_runs);
+
+    qtest_start("-machine npcm750-evb");
+    ret =3D g_test_run();
+    qtest_end();
+
+    return ret;
+}
diff --git a/hw/misc/meson.build b/hw/misc/meson.build
index 793d45b1dc4..7ffb44b587f 100644
--- a/hw/misc/meson.build
+++ b/hw/misc/meson.build
@@ -59,6 +59,7 @@ softmmu_ss.add(when: 'CONFIG_MAINSTONE', if_true: files('=
mst_fpga.c'))
 softmmu_ss.add(when: 'CONFIG_NPCM7XX', if_true: files(
   'npcm7xx_clk.c',
   'npcm7xx_gcr.c',
+  'npcm7xx_rng.c',
 ))
 softmmu_ss.add(when: 'CONFIG_OMAP', if_true: files(
   'omap_clk.c',
diff --git a/hw/misc/trace-events b/hw/misc/trace-events
index 6054f9adf35..b2f060ad774 100644
--- a/hw/misc/trace-events
+++ b/hw/misc/trace-events
@@ -118,6 +118,10 @@ npcm7xx_clk_write(uint64_t offset, uint32_t value) "of=
fset: 0x%04" PRIx64 " valu
 npcm7xx_gcr_read(uint64_t offset, uint32_t value) " offset: 0x%04" PRIx64 =
" value: 0x%08" PRIx32
 npcm7xx_gcr_write(uint64_t offset, uint32_t value) "offset: 0x%04" PRIx64 =
" value: 0x%08" PRIx32
=20
+# npcm7xx_rng.c
+npcm7xx_rng_read(uint64_t offset, uint64_t value, unsigned size) "offset: =
0x%04" PRIx64 " value: 0x%02" PRIx64 " size: %u"
+npcm7xx_rng_write(uint64_t offset, uint64_t value, unsigned size) "offset:=
 0x%04" PRIx64 " value: 0x%02" PRIx64 " size: %u"
+
 # stm32f4xx_syscfg.c
 stm32f4xx_syscfg_set_irq(int gpio, int line, int level) "Interupt: GPIO: %=
d, Line: %d; Level: %d"
 stm32f4xx_pulse_exti(int irq) "Pulse EXTI: %d"
diff --git a/tests/qtest/meson.build b/tests/qtest/meson.build
index 6c9d3426d1a..43e71a3d5ba 100644
--- a/tests/qtest/meson.build
+++ b/tests/qtest/meson.build
@@ -133,7 +133,10 @@ qtests_sparc64 =3D \
   (config_all_devices.has_key('CONFIG_ISA_TESTDEV') ? ['endianness-test'] =
: []) +            \
   ['prom-env-test', 'boot-serial-test']
=20
-qtests_npcm7xx =3D ['npcm7xx_timer-test', 'npcm7xx_watchdog_timer-test']
+qtests_npcm7xx =3D \
+  ['npcm7xx_rng-test',
+   'npcm7xx_timer-test',
+   'npcm7xx_watchdog_timer-test']
 qtests_arm =3D \
   (config_all_devices.has_key('CONFIG_PFLASH_CFI02') ? ['pflash-cfi02-test=
'] : []) +         \
   (config_all_devices.has_key('CONFIG_NPCM7XX') ? qtests_npcm7xx : []) + \
--=20
2.20.1