| /* |
| * QEMU EEPROM 93xx emulation |
| * |
| * Copyright (c) 2006-2007 Stefan Weil |
| * |
| * 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. |
| * |
| * You should have received a copy of the GNU General Public License |
| * along with this program; if not, write to the Free Software |
| * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA |
| */ |
| |
| /* Emulation for serial EEPROMs: |
| * NMC93C06 256-Bit (16 x 16) |
| * NMC93C46 1024-Bit (64 x 16) |
| * NMC93C56 2028 Bit (128 x 16) |
| * NMC93C66 4096 Bit (256 x 16) |
| * Compatible devices include FM93C46 and others. |
| * |
| * Other drivers use these interface functions: |
| * eeprom93xx_new - add a new EEPROM (with 16, 64 or 256 words) |
| * eeprom93xx_free - destroy EEPROM |
| * eeprom93xx_read - read data from the EEPROM |
| * eeprom93xx_write - write data to the EEPROM |
| * eeprom93xx_data - get EEPROM data array for external manipulation |
| * |
| * Todo list: |
| * - No emulation of EEPROM timings. |
| */ |
| |
| #include <assert.h> |
| #include "hw.h" |
| #include "eeprom93xx.h" |
| |
| /* Debug EEPROM emulation. */ |
| //~ #define DEBUG_EEPROM |
| |
| #ifdef DEBUG_EEPROM |
| #define logout(fmt, args...) fprintf(stderr, "EEPROM\t%-24s" fmt, __func__, ##args) |
| #else |
| #define logout(fmt, args...) ((void)0) |
| #endif |
| |
| static int eeprom_instance = 0; |
| static const int eeprom_version = 20061112; |
| |
| #if 0 |
| typedef enum { |
| eeprom_read = 0x80, /* read register xx */ |
| eeprom_write = 0x40, /* write register xx */ |
| eeprom_erase = 0xc0, /* erase register xx */ |
| eeprom_ewen = 0x30, /* erase / write enable */ |
| eeprom_ewds = 0x00, /* erase / write disable */ |
| eeprom_eral = 0x20, /* erase all registers */ |
| eeprom_wral = 0x10, /* write all registers */ |
| eeprom_amask = 0x0f, |
| eeprom_imask = 0xf0 |
| } eeprom_instruction_t; |
| #endif |
| |
| #ifdef DEBUG_EEPROM |
| static const char *opstring[] = { |
| "extended", "write", "read", "erase" |
| }; |
| #endif |
| |
| struct _eeprom_t { |
| uint8_t tick; |
| uint8_t address; |
| uint8_t command; |
| uint8_t writeable; |
| |
| uint8_t eecs; |
| uint8_t eesk; |
| uint8_t eedo; |
| |
| uint8_t addrbits; |
| uint8_t size; |
| uint16_t data; |
| uint16_t contents[0]; |
| }; |
| |
| /* Code for saving and restoring of EEPROM state. */ |
| |
| static void eeprom_save(QEMUFile *f, void *opaque) |
| { |
| /* Save EEPROM data. */ |
| unsigned address; |
| eeprom_t *eeprom = (eeprom_t *)opaque; |
| qemu_put_buffer(f, (uint8_t *)eeprom, sizeof(*eeprom) - 2); |
| qemu_put_be16(f, eeprom->data); |
| for (address = 0; address < eeprom->size; address++) { |
| qemu_put_be16(f, eeprom->contents[address]); |
| } |
| } |
| |
| static int eeprom_load(QEMUFile *f, void *opaque, int version_id) |
| { |
| /* Load EEPROM data from saved data if version and EEPROM size |
| of data and current EEPROM are identical. */ |
| eeprom_t *eeprom = (eeprom_t *)opaque; |
| int result = -EINVAL; |
| if (version_id == eeprom_version) { |
| unsigned address; |
| uint8_t size = eeprom->size; |
| qemu_get_buffer(f, (uint8_t *)eeprom, sizeof(*eeprom) - 2); |
| if (eeprom->size == size) { |
| eeprom->data = qemu_get_be16(f); |
| for (address = 0; address < eeprom->size; address++) { |
| eeprom->contents[address] = qemu_get_be16(f); |
| } |
| result = 0; |
| } |
| } |
| return result; |
| } |
| |
| void eeprom93xx_write(eeprom_t *eeprom, int eecs, int eesk, int eedi) |
| { |
| uint8_t tick = eeprom->tick; |
| uint8_t eedo = eeprom->eedo; |
| uint16_t address = eeprom->address; |
| uint8_t command = eeprom->command; |
| |
| logout("CS=%u SK=%u DI=%u DO=%u, tick = %u\n", |
| eecs, eesk, eedi, eedo, tick); |
| |
| if (! eeprom->eecs && eecs) { |
| /* Start chip select cycle. */ |
| logout("Cycle start, waiting for 1st start bit (0)\n"); |
| tick = 0; |
| command = 0x0; |
| address = 0x0; |
| } else if (eeprom->eecs && ! eecs) { |
| /* End chip select cycle. This triggers write / erase. */ |
| if (eeprom->writeable) { |
| uint8_t subcommand = address >> (eeprom->addrbits - 2); |
| if (command == 0 && subcommand == 2) { |
| /* Erase all. */ |
| for (address = 0; address < eeprom->size; address++) { |
| eeprom->contents[address] = 0xffff; |
| } |
| } else if (command == 3) { |
| /* Erase word. */ |
| eeprom->contents[address] = 0xffff; |
| } else if (tick >= 2 + 2 + eeprom->addrbits + 16) { |
| if (command == 1) { |
| /* Write word. */ |
| eeprom->contents[address] &= eeprom->data; |
| } else if (command == 0 && subcommand == 1) { |
| /* Write all. */ |
| for (address = 0; address < eeprom->size; address++) { |
| eeprom->contents[address] &= eeprom->data; |
| } |
| } |
| } |
| } |
| /* Output DO is tristate, read results in 1. */ |
| eedo = 1; |
| } else if (eecs && ! eeprom->eesk && eesk) { |
| /* Raising edge of clock shifts data in. */ |
| if (tick == 0) { |
| /* Wait for 1st start bit. */ |
| if (eedi == 0) { |
| logout("Got correct 1st start bit, waiting for 2nd start bit (1)\n"); |
| tick++; |
| } else { |
| logout("wrong 1st start bit (is 1, should be 0)\n"); |
| tick = 2; |
| //~ assert(!"wrong start bit"); |
| } |
| } else if (tick == 1) { |
| /* Wait for 2nd start bit. */ |
| if (eedi != 0) { |
| logout("Got correct 2nd start bit, getting command + address\n"); |
| tick++; |
| } else { |
| logout("1st start bit is longer than needed\n"); |
| } |
| } else if (tick < 2 + 2) { |
| /* Got 2 start bits, transfer 2 opcode bits. */ |
| tick++; |
| command <<= 1; |
| if (eedi) { |
| command += 1; |
| } |
| } else if (tick < 2 + 2 + eeprom->addrbits) { |
| /* Got 2 start bits and 2 opcode bits, transfer all address bits. */ |
| tick++; |
| address = ((address << 1) | eedi); |
| if (tick == 2 + 2 + eeprom->addrbits) { |
| logout("%s command, address = 0x%02x (value 0x%04x)\n", |
| opstring[command], address, eeprom->contents[address]); |
| if (command == 2) { |
| eedo = 0; |
| } |
| address = address % eeprom->size; |
| if (command == 0) { |
| /* Command code in upper 2 bits of address. */ |
| switch (address >> (eeprom->addrbits - 2)) { |
| case 0: |
| logout("write disable command\n"); |
| eeprom->writeable = 0; |
| break; |
| case 1: |
| logout("write all command\n"); |
| break; |
| case 2: |
| logout("erase all command\n"); |
| break; |
| case 3: |
| logout("write enable command\n"); |
| eeprom->writeable = 1; |
| break; |
| } |
| } else { |
| /* Read, write or erase word. */ |
| eeprom->data = eeprom->contents[address]; |
| } |
| } |
| } else if (tick < 2 + 2 + eeprom->addrbits + 16) { |
| /* Transfer 16 data bits. */ |
| tick++; |
| if (command == 2) { |
| /* Read word. */ |
| eedo = ((eeprom->data & 0x8000) != 0); |
| } |
| eeprom->data <<= 1; |
| eeprom->data += eedi; |
| } else { |
| logout("additional unneeded tick, not processed\n"); |
| } |
| } |
| /* Save status of EEPROM. */ |
| eeprom->tick = tick; |
| eeprom->eecs = eecs; |
| eeprom->eesk = eesk; |
| eeprom->eedo = eedo; |
| eeprom->address = address; |
| eeprom->command = command; |
| } |
| |
| uint16_t eeprom93xx_read(eeprom_t *eeprom) |
| { |
| /* Return status of pin DO (0 or 1). */ |
| logout("CS=%u DO=%u\n", eeprom->eecs, eeprom->eedo); |
| return (eeprom->eedo); |
| } |
| |
| #if 0 |
| void eeprom93xx_reset(eeprom_t *eeprom) |
| { |
| /* prepare eeprom */ |
| logout("eeprom = 0x%p\n", eeprom); |
| eeprom->tick = 0; |
| eeprom->command = 0; |
| } |
| #endif |
| |
| eeprom_t *eeprom93xx_new(uint16_t nwords) |
| { |
| /* Add a new EEPROM (with 16, 64 or 256 words). */ |
| eeprom_t *eeprom; |
| uint8_t addrbits; |
| |
| switch (nwords) { |
| case 16: |
| case 64: |
| addrbits = 6; |
| break; |
| case 128: |
| case 256: |
| addrbits = 8; |
| break; |
| default: |
| assert(!"Unsupported EEPROM size, fallback to 64 words!"); |
| nwords = 64; |
| addrbits = 6; |
| } |
| |
| eeprom = (eeprom_t *)qemu_mallocz(sizeof(*eeprom) + nwords * 2); |
| eeprom->size = nwords; |
| eeprom->addrbits = addrbits; |
| /* Output DO is tristate, read results in 1. */ |
| eeprom->eedo = 1; |
| logout("eeprom = 0x%p, nwords = %u\n", eeprom, nwords); |
| register_savevm("eeprom", eeprom_instance, eeprom_version, |
| eeprom_save, eeprom_load, eeprom); |
| return eeprom; |
| } |
| |
| void eeprom93xx_free(eeprom_t *eeprom) |
| { |
| /* Destroy EEPROM. */ |
| logout("eeprom = 0x%p\n", eeprom); |
| qemu_free(eeprom); |
| } |
| |
| uint16_t *eeprom93xx_data(eeprom_t *eeprom) |
| { |
| /* Get EEPROM data array. */ |
| return &eeprom->contents[0]; |
| } |
| |
| /* eof */ |
