diff options
Diffstat (limited to 'hw/misc/npcm7xx_rng.c')
| -rw-r--r-- | hw/misc/npcm7xx_rng.c | 180 |
1 files changed, 180 insertions, 0 deletions
diff --git a/hw/misc/npcm7xx_rng.c b/hw/misc/npcm7xx_rng.c new file mode 100644 index 0000000000..f650f3401f --- /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 WITHOUT + * 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 == NPCM7XX_RNGMODE_NORMAL); +} + +static uint64_t npcm7xx_rng_read(void *opaque, hwaddr offset, unsigned size) +{ + NPCM7xxRNGState *s = opaque; + uint64_t value = 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 &= ~NPCM7XX_RNGCS_DVALID; + } else if (!(s->rngcs & NPCM7XX_RNGCS_DVALID)) { + uint8_t byte = 0; + + if (qemu_guest_getrandom(&byte, sizeof(byte), NULL) == 0) { + s->rngd = byte; + s->rngcs |= NPCM7XX_RNGCS_DVALID; + } + } + value = s->rngcs; + break; + case NPCM7XX_RNGD: + if (npcm7xx_rng_is_enabled(s) && s->rngcs & NPCM7XX_RNGCS_DVALID) { + s->rngcs &= ~NPCM7XX_RNGCS_DVALID; + value = s->rngd; + s->rngd = 0; + } + break; + case NPCM7XX_RNGMODE: + value = 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 = opaque; + + trace_npcm7xx_rng_write(offset, value, size); + + switch (offset) { + case NPCM7XX_RNGCS: + s->rngcs &= NPCM7XX_RNGCS_DVALID; + s->rngcs |= 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 = 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 = { + .read = npcm7xx_rng_read, + .write = npcm7xx_rng_write, + .endianness = DEVICE_LITTLE_ENDIAN, + .valid = { + .min_access_size = 1, + .max_access_size = 4, + .unaligned = false, + }, +}; + +static void npcm7xx_rng_enter_reset(Object *obj, ResetType type) +{ + NPCM7xxRNGState *s = NPCM7XX_RNG(obj); + + s->rngcs = 0; + s->rngd = 0; + s->rngmode = 0; +} + +static void npcm7xx_rng_init(Object *obj) +{ + NPCM7xxRNGState *s = 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 = { + .name = "npcm7xx-rng", + .version_id = 0, + .minimum_version_id = 0, + .fields = (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 = RESETTABLE_CLASS(klass); + DeviceClass *dc = DEVICE_CLASS(klass); + + dc->desc = "NPCM7xx Random Number Generator"; + dc->vmsd = &vmstate_npcm7xx_rng; + rc->phases.enter = npcm7xx_rng_enter_reset; +} + +static const TypeInfo npcm7xx_rng_types[] = { + { + .name = TYPE_NPCM7XX_RNG, + .parent = TYPE_SYS_BUS_DEVICE, + .instance_size = sizeof(NPCM7xxRNGState), + .class_init = npcm7xx_rng_class_init, + .instance_init = npcm7xx_rng_init, + }, +}; +DEFINE_TYPES(npcm7xx_rng_types); |