/* * Freescale i.MX RNGC emulation * * Copyright (C) 2020 Martin Kaiser * * This work is licensed under the terms of the GNU GPL, version 2 or later. * See the COPYING file in the top-level directory. * * This driver provides the minimum functionality to initialize and seed * an rngc and to read random numbers. The rngb that is found in imx25 * chipsets is also supported. */ #include "qemu/osdep.h" #include "qemu/main-loop.h" #include "qemu/module.h" #include "qemu/guest-random.h" #include "hw/irq.h" #include "hw/misc/imx_rngc.h" #include "migration/vmstate.h" #define RNGC_NAME "i.MX RNGC" #define RNGC_VER_ID 0x00 #define RNGC_COMMAND 0x04 #define RNGC_CONTROL 0x08 #define RNGC_STATUS 0x0C #define RNGC_FIFO 0x14 /* These version info are reported by the rngb in an imx258 chip. */ #define RNG_TYPE_RNGB 0x1 #define V_MAJ 0x2 #define V_MIN 0x40 #define RNGC_CMD_BIT_SW_RST 0x40 #define RNGC_CMD_BIT_CLR_ERR 0x20 #define RNGC_CMD_BIT_CLR_INT 0x10 #define RNGC_CMD_BIT_SEED 0x02 #define RNGC_CMD_BIT_SELF_TEST 0x01 #define RNGC_CTRL_BIT_MASK_ERR 0x40 #define RNGC_CTRL_BIT_MASK_DONE 0x20 #define RNGC_CTRL_BIT_AUTO_SEED 0x10 /* the current status for self-test and seed operations */ #define OP_IDLE 0 #define OP_RUN 1 #define OP_DONE 2 static uint64_t imx_rngc_read(void *opaque, hwaddr offset, unsigned size) { IMXRNGCState *s = IMX_RNGC(opaque); uint64_t val = 0; switch (offset) { case RNGC_VER_ID: val |= RNG_TYPE_RNGB << 28 | V_MAJ << 8 | V_MIN; break; case RNGC_COMMAND: if (s->op_seed == OP_RUN) { val |= RNGC_CMD_BIT_SEED; } if (s->op_self_test == OP_RUN) { val |= RNGC_CMD_BIT_SELF_TEST; } break; case RNGC_CONTROL: /* * The CTL_ACC and VERIF_MODE bits are not supported yet. * They read as 0. */ val |= s->mask; if (s->auto_seed) { val |= RNGC_CTRL_BIT_AUTO_SEED; } /* * We don't have an internal fifo like the real hardware. * There's no need for strategy to handle fifo underflows. * We return the FIFO_UFLOW_RESPONSE bits as 0. */ break; case RNGC_STATUS: /* * We never report any statistics test or self-test errors or any * other errors. STAT_TEST_PF, ST_PF and ERROR are always 0. */ /* * We don't have an internal fifo, see above. Therefore, we * report back the default fifo size (5 32-bit words) and * indicate that our fifo is always full. */ val |= 5 << 12 | 5 << 8; /* We always have a new seed available. */ val |= 1 << 6; if (s->op_seed == OP_DONE) { val |= 1 << 5; } if (s->op_self_test == OP_DONE) { val |= 1 << 4; } if (s->op_seed == OP_RUN || s->op_self_test == OP_RUN) { /* * We're busy if self-test is running or if we're * seeding the prng. */ val |= 1 << 1; } else { /* * We're ready to provide secure random numbers whenever * we're not busy. */ val |= 1; } break; case RNGC_FIFO: qemu_guest_getrandom_nofail(&val, sizeof(val)); break; } return val; } static void imx_rngc_do_reset(IMXRNGCState *s) { s->op_self_test = OP_IDLE; s->op_seed = OP_IDLE; s->mask = 0; s->auto_seed = false; } static void imx_rngc_write(void *opaque, hwaddr offset, uint64_t value, unsigned size) { IMXRNGCState *s = IMX_RNGC(opaque); switch (offset) { case RNGC_COMMAND: if (value & RNGC_CMD_BIT_SW_RST) { imx_rngc_do_reset(s); } /* * For now, both CLR_ERR and CLR_INT clear the interrupt. We * don't report any errors yet. */ if (value & (RNGC_CMD_BIT_CLR_ERR | RNGC_CMD_BIT_CLR_INT)) { qemu_irq_lower(s->irq); } if (value & RNGC_CMD_BIT_SEED) { s->op_seed = OP_RUN; qemu_bh_schedule(s->seed_bh); } if (value & RNGC_CMD_BIT_SELF_TEST) { s->op_self_test = OP_RUN; qemu_bh_schedule(s->self_test_bh); } break; case RNGC_CONTROL: /* * The CTL_ACC and VERIF_MODE bits are not supported yet. * We ignore them if they're set by the caller. */ if (value & RNGC_CTRL_BIT_MASK_ERR) { s->mask |= RNGC_CTRL_BIT_MASK_ERR; } else { s->mask &= ~RNGC_CTRL_BIT_MASK_ERR; } if (value & RNGC_CTRL_BIT_MASK_DONE) { s->mask |= RNGC_CTRL_BIT_MASK_DONE; } else { s->mask &= ~RNGC_CTRL_BIT_MASK_DONE; } if (value & RNGC_CTRL_BIT_AUTO_SEED) { s->auto_seed = true; } else { s->auto_seed = false; } break; } } static const MemoryRegionOps imx_rngc_ops = { .read = imx_rngc_read, .write = imx_rngc_write, .endianness = DEVICE_NATIVE_ENDIAN, }; static void imx_rngc_self_test(void *opaque) { IMXRNGCState *s = IMX_RNGC(opaque); s->op_self_test = OP_DONE; if (!(s->mask & RNGC_CTRL_BIT_MASK_DONE)) { qemu_irq_raise(s->irq); } } static void imx_rngc_seed(void *opaque) { IMXRNGCState *s = IMX_RNGC(opaque); s->op_seed = OP_DONE; if (!(s->mask & RNGC_CTRL_BIT_MASK_DONE)) { qemu_irq_raise(s->irq); } } static void imx_rngc_realize(DeviceState *dev, Error **errp) { IMXRNGCState *s = IMX_RNGC(dev); SysBusDevice *sbd = SYS_BUS_DEVICE(dev); memory_region_init_io(&s->iomem, OBJECT(s), &imx_rngc_ops, s, TYPE_IMX_RNGC, 0x1000); sysbus_init_mmio(sbd, &s->iomem); sysbus_init_irq(sbd, &s->irq); s->self_test_bh = qemu_bh_new_guarded(imx_rngc_self_test, s, &dev->mem_reentrancy_guard); s->seed_bh = qemu_bh_new_guarded(imx_rngc_seed, s, &dev->mem_reentrancy_guard); } static void imx_rngc_reset(DeviceState *dev) { IMXRNGCState *s = IMX_RNGC(dev); imx_rngc_do_reset(s); } static const VMStateDescription vmstate_imx_rngc = { .name = RNGC_NAME, .version_id = 1, .minimum_version_id = 1, .fields = (const VMStateField[]) { VMSTATE_UINT8(op_self_test, IMXRNGCState), VMSTATE_UINT8(op_seed, IMXRNGCState), VMSTATE_UINT8(mask, IMXRNGCState), VMSTATE_BOOL(auto_seed, IMXRNGCState), VMSTATE_END_OF_LIST() } }; static void imx_rngc_class_init(ObjectClass *klass, void *data) { DeviceClass *dc = DEVICE_CLASS(klass); dc->realize = imx_rngc_realize; device_class_set_legacy_reset(dc, imx_rngc_reset); dc->desc = RNGC_NAME, dc->vmsd = &vmstate_imx_rngc; } static const TypeInfo imx_rngc_info = { .name = TYPE_IMX_RNGC, .parent = TYPE_SYS_BUS_DEVICE, .instance_size = sizeof(IMXRNGCState), .class_init = imx_rngc_class_init, }; static void imx_rngc_register_types(void) { type_register_static(&imx_rngc_info); } type_init(imx_rngc_register_types)