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Diffstat (limited to 'hw/nvram/npcm7xx_otp.c')
| -rw-r--r-- | hw/nvram/npcm7xx_otp.c | 440 |
1 files changed, 440 insertions, 0 deletions
diff --git a/hw/nvram/npcm7xx_otp.c b/hw/nvram/npcm7xx_otp.c new file mode 100644 index 0000000..b16ca53 --- /dev/null +++ b/hw/nvram/npcm7xx_otp.c @@ -0,0 +1,440 @@ +/* + * Nuvoton NPCM7xx OTP (Fuse Array) Interface + * + * 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/nvram/npcm7xx_otp.h" +#include "migration/vmstate.h" +#include "qapi/error.h" +#include "qemu/bitops.h" +#include "qemu/log.h" +#include "qemu/module.h" +#include "qemu/units.h" + +/* Each module has 4 KiB of register space. Only a fraction of it is used. */ +#define NPCM7XX_OTP_REGS_SIZE (4 * KiB) + +/* 32-bit register indices. */ +typedef enum NPCM7xxOTPRegister { + NPCM7XX_OTP_FST, + NPCM7XX_OTP_FADDR, + NPCM7XX_OTP_FDATA, + NPCM7XX_OTP_FCFG, + /* Offset 0x10 is FKEYIND in OTP1, FUSTRAP in OTP2 */ + NPCM7XX_OTP_FKEYIND = 0x0010 / sizeof(uint32_t), + NPCM7XX_OTP_FUSTRAP = 0x0010 / sizeof(uint32_t), + NPCM7XX_OTP_FCTL, + NPCM7XX_OTP_REGS_END, +} NPCM7xxOTPRegister; + +/* Register field definitions. */ +#define FST_RIEN BIT(2) +#define FST_RDST BIT(1) +#define FST_RDY BIT(0) +#define FST_RO_MASK (FST_RDST | FST_RDY) + +#define FADDR_BYTEADDR(rv) extract32((rv), 0, 10) +#define FADDR_BITPOS(rv) extract32((rv), 10, 3) + +#define FDATA_CLEAR 0x00000001 + +#define FCFG_FDIS BIT(31) +#define FCFG_FCFGLK_MASK 0x00ff0000 + +#define FCTL_PROG_CMD1 0x00000001 +#define FCTL_PROG_CMD2 0xbf79e5d0 +#define FCTL_READ_CMD 0x00000002 + +/** + * struct NPCM7xxOTPClass - OTP module class. + * @parent: System bus device class. + * @mmio_ops: MMIO register operations for this type of module. + * + * The two OTP modules (key-storage and fuse-array) have slightly different + * behavior, so we give them different MMIO register operations. + */ +struct NPCM7xxOTPClass { + SysBusDeviceClass parent; + + const MemoryRegionOps *mmio_ops; +}; + +#define NPCM7XX_OTP_CLASS(klass) \ + OBJECT_CLASS_CHECK(NPCM7xxOTPClass, (klass), TYPE_NPCM7XX_OTP) +#define NPCM7XX_OTP_GET_CLASS(obj) \ + OBJECT_GET_CLASS(NPCM7xxOTPClass, (obj), TYPE_NPCM7XX_OTP) + +static uint8_t ecc_encode_nibble(uint8_t n) +{ + uint8_t result = n; + + result |= (((n >> 0) & 1) ^ ((n >> 1) & 1)) << 4; + result |= (((n >> 2) & 1) ^ ((n >> 3) & 1)) << 5; + result |= (((n >> 0) & 1) ^ ((n >> 2) & 1)) << 6; + result |= (((n >> 1) & 1) ^ ((n >> 3) & 1)) << 7; + + return result; +} + +void npcm7xx_otp_array_write(NPCM7xxOTPState *s, const void *data, + unsigned int offset, unsigned int len) +{ + const uint8_t *src = data; + uint8_t *dst = &s->array[offset]; + + while (len-- > 0) { + uint8_t c = *src++; + + *dst++ = ecc_encode_nibble(extract8(c, 0, 4)); + *dst++ = ecc_encode_nibble(extract8(c, 4, 4)); + } +} + +/* Common register read handler for both OTP classes. */ +static uint64_t npcm7xx_otp_read(NPCM7xxOTPState *s, NPCM7xxOTPRegister reg) +{ + uint32_t value = 0; + + switch (reg) { + case NPCM7XX_OTP_FST: + case NPCM7XX_OTP_FADDR: + case NPCM7XX_OTP_FDATA: + case NPCM7XX_OTP_FCFG: + value = s->regs[reg]; + break; + + case NPCM7XX_OTP_FCTL: + qemu_log_mask(LOG_GUEST_ERROR, + "%s: read from write-only FCTL register\n", + DEVICE(s)->canonical_path); + break; + + default: + qemu_log_mask(LOG_GUEST_ERROR, "%s: read from invalid offset 0x%zx\n", + DEVICE(s)->canonical_path, reg * sizeof(uint32_t)); + break; + } + + return value; +} + +/* Read a byte from the OTP array into the data register. */ +static void npcm7xx_otp_read_array(NPCM7xxOTPState *s) +{ + uint32_t faddr = s->regs[NPCM7XX_OTP_FADDR]; + + s->regs[NPCM7XX_OTP_FDATA] = s->array[FADDR_BYTEADDR(faddr)]; + s->regs[NPCM7XX_OTP_FST] |= FST_RDST | FST_RDY; +} + +/* Program a byte from the data register into the OTP array. */ +static void npcm7xx_otp_program_array(NPCM7xxOTPState *s) +{ + uint32_t faddr = s->regs[NPCM7XX_OTP_FADDR]; + + /* Bits can only go 0->1, never 1->0. */ + s->array[FADDR_BYTEADDR(faddr)] |= (1U << FADDR_BITPOS(faddr)); + s->regs[NPCM7XX_OTP_FST] |= FST_RDST | FST_RDY; +} + +/* Compute the next value of the FCFG register. */ +static uint32_t npcm7xx_otp_compute_fcfg(uint32_t cur_value, uint32_t new_value) +{ + uint32_t lock_mask; + uint32_t value; + + /* + * FCFGLK holds sticky bits 16..23, indicating which bits in FPRGLK (8..15) + * and FRDLK (0..7) that are read-only. + */ + lock_mask = (cur_value & FCFG_FCFGLK_MASK) >> 8; + lock_mask |= lock_mask >> 8; + /* FDIS and FCFGLK bits are sticky (write 1 to set; can't clear). */ + value = cur_value & (FCFG_FDIS | FCFG_FCFGLK_MASK); + /* Preserve read-only bits in FPRGLK and FRDLK */ + value |= cur_value & lock_mask; + /* Set all bits that aren't read-only. */ + value |= new_value & ~lock_mask; + + return value; +} + +/* Common register write handler for both OTP classes. */ +static void npcm7xx_otp_write(NPCM7xxOTPState *s, NPCM7xxOTPRegister reg, + uint32_t value) +{ + switch (reg) { + case NPCM7XX_OTP_FST: + /* RDST is cleared by writing 1 to it. */ + if (value & FST_RDST) { + s->regs[NPCM7XX_OTP_FST] &= ~FST_RDST; + } + /* Preserve read-only and write-one-to-clear bits */ + value &= ~FST_RO_MASK; + value |= s->regs[NPCM7XX_OTP_FST] & FST_RO_MASK; + break; + + case NPCM7XX_OTP_FADDR: + break; + + case NPCM7XX_OTP_FDATA: + /* + * This register is cleared by writing a magic value to it; no other + * values can be written. + */ + if (value == FDATA_CLEAR) { + value = 0; + } else { + value = s->regs[NPCM7XX_OTP_FDATA]; + } + break; + + case NPCM7XX_OTP_FCFG: + value = npcm7xx_otp_compute_fcfg(s->regs[NPCM7XX_OTP_FCFG], value); + break; + + case NPCM7XX_OTP_FCTL: + switch (value) { + case FCTL_READ_CMD: + npcm7xx_otp_read_array(s); + break; + + case FCTL_PROG_CMD1: + /* + * Programming requires writing two separate magic values to this + * register; this is the first one. Just store it so it can be + * verified later when the second magic value is received. + */ + break; + + case FCTL_PROG_CMD2: + /* + * Only initiate programming if we received the first half of the + * command immediately before this one. + */ + if (s->regs[NPCM7XX_OTP_FCTL] == FCTL_PROG_CMD1) { + npcm7xx_otp_program_array(s); + } + break; + + default: + qemu_log_mask(LOG_GUEST_ERROR, + "%s: unrecognized FCNTL value 0x%" PRIx32 "\n", + DEVICE(s)->canonical_path, value); + break; + } + if (value != FCTL_PROG_CMD1) { + value = 0; + } + break; + + default: + qemu_log_mask(LOG_GUEST_ERROR, "%s: write to invalid offset 0x%zx\n", + DEVICE(s)->canonical_path, reg * sizeof(uint32_t)); + return; + } + + s->regs[reg] = value; +} + +/* Register read handler specific to the fuse array OTP module. */ +static uint64_t npcm7xx_fuse_array_read(void *opaque, hwaddr addr, + unsigned int size) +{ + NPCM7xxOTPRegister reg = addr / sizeof(uint32_t); + NPCM7xxOTPState *s = opaque; + uint32_t value; + + /* + * Only the Fuse Strap register needs special handling; all other registers + * work the same way for both kinds of OTP modules. + */ + if (reg != NPCM7XX_OTP_FUSTRAP) { + value = npcm7xx_otp_read(s, reg); + } else { + /* FUSTRAP is stored as three copies in the OTP array. */ + uint32_t fustrap[3]; + + memcpy(fustrap, &s->array[0], sizeof(fustrap)); + + /* Determine value by a majority vote on each bit. */ + value = (fustrap[0] & fustrap[1]) | (fustrap[0] & fustrap[2]) | + (fustrap[1] & fustrap[2]); + } + + return value; +} + +/* Register write handler specific to the fuse array OTP module. */ +static void npcm7xx_fuse_array_write(void *opaque, hwaddr addr, uint64_t v, + unsigned int size) +{ + NPCM7xxOTPRegister reg = addr / sizeof(uint32_t); + NPCM7xxOTPState *s = opaque; + + /* + * The Fuse Strap register is read-only. Other registers are handled by + * common code. + */ + if (reg != NPCM7XX_OTP_FUSTRAP) { + npcm7xx_otp_write(s, reg, v); + } +} + +static const MemoryRegionOps npcm7xx_fuse_array_ops = { + .read = npcm7xx_fuse_array_read, + .write = npcm7xx_fuse_array_write, + .endianness = DEVICE_LITTLE_ENDIAN, + .valid = { + .min_access_size = 4, + .max_access_size = 4, + .unaligned = false, + }, +}; + +/* Register read handler specific to the key storage OTP module. */ +static uint64_t npcm7xx_key_storage_read(void *opaque, hwaddr addr, + unsigned int size) +{ + NPCM7xxOTPRegister reg = addr / sizeof(uint32_t); + NPCM7xxOTPState *s = opaque; + + /* + * Only the Fuse Key Index register needs special handling; all other + * registers work the same way for both kinds of OTP modules. + */ + if (reg != NPCM7XX_OTP_FKEYIND) { + return npcm7xx_otp_read(s, reg); + } + + qemu_log_mask(LOG_UNIMP, "%s: FKEYIND is not implemented\n", __func__); + + return s->regs[NPCM7XX_OTP_FKEYIND]; +} + +/* Register write handler specific to the key storage OTP module. */ +static void npcm7xx_key_storage_write(void *opaque, hwaddr addr, uint64_t v, + unsigned int size) +{ + NPCM7xxOTPRegister reg = addr / sizeof(uint32_t); + NPCM7xxOTPState *s = opaque; + + /* + * Only the Fuse Key Index register needs special handling; all other + * registers work the same way for both kinds of OTP modules. + */ + if (reg != NPCM7XX_OTP_FKEYIND) { + npcm7xx_otp_write(s, reg, v); + return; + } + + qemu_log_mask(LOG_UNIMP, "%s: FKEYIND is not implemented\n", __func__); + + s->regs[NPCM7XX_OTP_FKEYIND] = v; +} + +static const MemoryRegionOps npcm7xx_key_storage_ops = { + .read = npcm7xx_key_storage_read, + .write = npcm7xx_key_storage_write, + .endianness = DEVICE_LITTLE_ENDIAN, + .valid = { + .min_access_size = 4, + .max_access_size = 4, + .unaligned = false, + }, +}; + +static void npcm7xx_otp_enter_reset(Object *obj, ResetType type) +{ + NPCM7xxOTPState *s = NPCM7XX_OTP(obj); + + memset(s->regs, 0, sizeof(s->regs)); + + s->regs[NPCM7XX_OTP_FST] = 0x00000001; + s->regs[NPCM7XX_OTP_FCFG] = 0x20000000; +} + +static void npcm7xx_otp_realize(DeviceState *dev, Error **errp) +{ + NPCM7xxOTPClass *oc = NPCM7XX_OTP_GET_CLASS(dev); + NPCM7xxOTPState *s = NPCM7XX_OTP(dev); + SysBusDevice *sbd = &s->parent; + + memset(s->array, 0, sizeof(s->array)); + + memory_region_init_io(&s->mmio, OBJECT(s), oc->mmio_ops, s, "regs", + NPCM7XX_OTP_REGS_SIZE); + sysbus_init_mmio(sbd, &s->mmio); +} + +static const VMStateDescription vmstate_npcm7xx_otp = { + .name = "npcm7xx-otp", + .version_id = 0, + .minimum_version_id = 0, + .fields = (VMStateField[]) { + VMSTATE_UINT32_ARRAY(regs, NPCM7xxOTPState, NPCM7XX_OTP_NR_REGS), + VMSTATE_UINT8_ARRAY(array, NPCM7xxOTPState, NPCM7XX_OTP_ARRAY_BYTES), + VMSTATE_END_OF_LIST(), + }, +}; + +static void npcm7xx_otp_class_init(ObjectClass *klass, void *data) +{ + ResettableClass *rc = RESETTABLE_CLASS(klass); + DeviceClass *dc = DEVICE_CLASS(klass); + + QEMU_BUILD_BUG_ON(NPCM7XX_OTP_REGS_END > NPCM7XX_OTP_NR_REGS); + + dc->realize = npcm7xx_otp_realize; + dc->vmsd = &vmstate_npcm7xx_otp; + rc->phases.enter = npcm7xx_otp_enter_reset; +} + +static void npcm7xx_key_storage_class_init(ObjectClass *klass, void *data) +{ + NPCM7xxOTPClass *oc = NPCM7XX_OTP_CLASS(klass); + + oc->mmio_ops = &npcm7xx_key_storage_ops; +} + +static void npcm7xx_fuse_array_class_init(ObjectClass *klass, void *data) +{ + NPCM7xxOTPClass *oc = NPCM7XX_OTP_CLASS(klass); + + oc->mmio_ops = &npcm7xx_fuse_array_ops; +} + +static const TypeInfo npcm7xx_otp_types[] = { + { + .name = TYPE_NPCM7XX_OTP, + .parent = TYPE_SYS_BUS_DEVICE, + .instance_size = sizeof(NPCM7xxOTPState), + .class_size = sizeof(NPCM7xxOTPClass), + .class_init = npcm7xx_otp_class_init, + .abstract = true, + }, + { + .name = TYPE_NPCM7XX_KEY_STORAGE, + .parent = TYPE_NPCM7XX_OTP, + .class_init = npcm7xx_key_storage_class_init, + }, + { + .name = TYPE_NPCM7XX_FUSE_ARRAY, + .parent = TYPE_NPCM7XX_OTP, + .class_init = npcm7xx_fuse_array_class_init, + }, +}; +DEFINE_TYPES(npcm7xx_otp_types); |