/* * 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 */