Mercurial > repos > blastem
view i2c.c @ 2321:2eda5f81f91e
More fully baked ROM db support for SMS
author | Michael Pavone <pavone@retrodev.com> |
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date | Thu, 15 Jun 2023 09:36:11 -0700 |
parents | d94855080529 |
children |
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#include "genesis.h" #include "util.h" enum { I2C_IDLE, I2C_START, I2C_DEVICE_ACK, I2C_ADDRESS_HI, I2C_ADDRESS_HI_ACK, I2C_ADDRESS, I2C_ADDRESS_ACK, I2C_READ, I2C_READ_ACK, I2C_WRITE, I2C_WRITE_ACK }; char * i2c_states[] = { "idle", "start", "device ack", "address hi", "address hi ack", "address", "address ack", "read", "read_ack", "write", "write_ack" }; void eeprom_init(eeprom_state *state, uint8_t *buffer, uint32_t size) { state->slave_sda = 1; state->host_sda = state->scl = 0; state->buffer = buffer; state->size = size; state->state = I2C_IDLE; } void set_host_sda(eeprom_state *state, uint8_t val) { if (state->scl) { if (val & ~state->host_sda) { //low to high, stop condition state->state = I2C_IDLE; state->slave_sda = 1; } else if (~val & state->host_sda) { //high to low, start condition state->state = I2C_START; state->slave_sda = 1; state->counter = 8; } } state->host_sda = val; } void set_scl(eeprom_state *state, uint8_t val) { if (val & ~state->scl) { //low to high transition switch (state->state) { case I2C_START: case I2C_ADDRESS_HI: case I2C_ADDRESS: case I2C_WRITE: state->latch = state->host_sda | state->latch << 1; state->counter--; if (!state->counter) { switch (state->state & 0x7F) { case I2C_START: state->state = I2C_DEVICE_ACK; break; case I2C_ADDRESS_HI: state->address = state->latch << 8; state->state = I2C_ADDRESS_HI_ACK; break; case I2C_ADDRESS: state->address |= state->latch; state->state = I2C_ADDRESS_ACK; break; case I2C_WRITE: state->buffer[state->address] = state->latch; state->state = I2C_WRITE_ACK; break; } } break; case I2C_DEVICE_ACK: if (state->latch & 1) { state->state = I2C_READ; state->counter = 8; if (state->size < 256) { state->address = state->latch >> 1; } state->latch = state->buffer[state->address]; } else { if (state->size < 256) { state->address = state->latch >> 1; state->state = I2C_WRITE; } else if (state->size < 4096) { state->address = (state->latch & 0xE) << 7; state->state = I2C_ADDRESS; } else { state->state = I2C_ADDRESS_HI; } state->counter = 8; } break; case I2C_ADDRESS_HI_ACK: state->state = I2C_ADDRESS; state->counter = 8; break; case I2C_ADDRESS_ACK: state->state = I2C_WRITE; state->address &= state->size-1; state->counter = 8; break; case I2C_READ: state->counter--; if (!state->counter) { state->state = I2C_READ_ACK; } break; case I2C_READ_ACK: state->state = I2C_READ; state->counter = 8; state->address++; //TODO: page mask state->address &= state->size-1; state->latch = state->buffer[state->address]; break; case I2C_WRITE_ACK: state->state = I2C_WRITE; state->counter = 8; state->address++; //TODO: page mask state->address &= state->size-1; break; } } else if (~val & state->scl) { //high to low transition switch (state->state & 0x7F) { case I2C_DEVICE_ACK: case I2C_ADDRESS_HI_ACK: case I2C_ADDRESS_ACK: case I2C_READ_ACK: case I2C_WRITE_ACK: state->slave_sda = 0; break; case I2C_READ: state->slave_sda = state->latch >> 7; state->latch = state->latch << 1; break; default: state->slave_sda = 1; break; } } state->scl = val; } uint8_t get_sda(eeprom_state *state) { return state->host_sda & state->slave_sda; } eeprom_map *find_eeprom_map(uint32_t address, genesis_context *gen) { for (int i = 0; i < gen->num_eeprom; i++) { if (address >= gen->eeprom_map[i].start && address <= gen->eeprom_map[i].end) { return gen->eeprom_map + i; } } return NULL; } void * write_eeprom_i2c_w(uint32_t address, void * context, uint16_t value) { genesis_context *gen = ((m68k_context *)context)->system; eeprom_map *map = find_eeprom_map(address, gen); if (!map) { fatal_error("Could not find EEPROM map for address %X\n", address); } if (map->scl_mask) { set_scl(&gen->eeprom, (value & map->scl_mask) != 0); } if (map->sda_write_mask) { set_host_sda(&gen->eeprom, (value & map->sda_write_mask) != 0); } return context; } void * write_eeprom_i2c_b(uint32_t address, void * context, uint8_t value) { genesis_context *gen = ((m68k_context *)context)->system; eeprom_map *map = find_eeprom_map(address, gen); if (!map) { fatal_error("Could not find EEPROM map for address %X\n", address); } uint16_t expanded, mask; if (address & 1) { expanded = value; mask = 0xFF; } else { expanded = value << 8; mask = 0xFF00; } if (map->scl_mask & mask) { set_scl(&gen->eeprom, (expanded & map->scl_mask) != 0); } if (map->sda_write_mask & mask) { set_host_sda(&gen->eeprom, (expanded & map->sda_write_mask) != 0); } return context; } uint16_t read_eeprom_i2c_w(uint32_t address, void * context) { genesis_context *gen = ((m68k_context *)context)->system; eeprom_map *map = find_eeprom_map(address, gen); if (!map) { fatal_error("Could not find EEPROM map for address %X\n", address); } uint16_t ret = 0; if (map->sda_read_bit < 16) { ret = get_sda(&gen->eeprom) << map->sda_read_bit; } return ret; } uint8_t read_eeprom_i2c_b(uint32_t address, void * context) { genesis_context *gen = ((m68k_context *)context)->system; eeprom_map *map = find_eeprom_map(address, gen); if (!map) { fatal_error("Could not find EEPROM map for address %X\n", address); } uint8_t bit = address & 1 ? map->sda_read_bit : map->sda_read_bit - 8; uint8_t ret = 0; if (bit < 8) { ret = get_sda(&gen->eeprom) << bit; } return ret; }