root / hw / eeprom93xx.c @ 83fa1010
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/*
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* QEMU EEPROM 93xx emulation
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*
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* Copyright (c) 2006-2007 Stefan Weil
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
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*/
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/* Emulation for serial EEPROMs:
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* NMC93C06 256-Bit (16 x 16)
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* NMC93C46 1024-Bit (64 x 16)
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* NMC93C56 2028 Bit (128 x 16)
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* NMC93C66 4096 Bit (256 x 16)
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* Compatible devices include FM93C46 and others.
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*
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* Other drivers use these interface functions:
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* eeprom93xx_new - add a new EEPROM (with 16, 64 or 256 words)
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* eeprom93xx_free - destroy EEPROM
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* eeprom93xx_read - read data from the EEPROM
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* eeprom93xx_write - write data to the EEPROM
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* eeprom93xx_data - get EEPROM data array for external manipulation
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*
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* Todo list:
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* - No emulation of EEPROM timings.
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*/
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#include <assert.h> |
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#include "eeprom93xx.h" |
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/* Debug EEPROM emulation. */
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//~ #define DEBUG_EEPROM
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#ifdef DEBUG_EEPROM
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#define logout(fmt, args...) fprintf(stderr, "EEPROM\t%-24s" fmt, __func__, ##args) |
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#else
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#define logout(fmt, args...) ((void)0) |
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#endif
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static int eeprom_instance = 0; |
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static const int eeprom_version = 20061112; |
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#if 0
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typedef enum {
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eeprom_read = 0x80, /* read register xx */
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eeprom_write = 0x40, /* write register xx */
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eeprom_erase = 0xc0, /* erase register xx */
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eeprom_ewen = 0x30, /* erase / write enable */
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eeprom_ewds = 0x00, /* erase / write disable */
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eeprom_eral = 0x20, /* erase all registers */
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eeprom_wral = 0x10, /* write all registers */
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eeprom_amask = 0x0f,
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eeprom_imask = 0xf0
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} eeprom_instruction_t;
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#endif
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#ifdef DEBUG_EEPROM
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static const char *opstring[] = { |
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"extended", "write", "read", "erase" |
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}; |
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#endif
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struct _eeprom_t {
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uint8_t tick; |
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uint8_t address; |
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uint8_t command; |
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uint8_t writeable; |
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uint8_t eecs; |
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uint8_t eesk; |
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uint8_t eedo; |
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uint8_t addrbits; |
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uint8_t size; |
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uint16_t data; |
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uint16_t contents[0];
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}; |
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/* Code for saving and restoring of EEPROM state. */
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static void eeprom_save(QEMUFile *f, void *opaque) |
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{ |
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/* Save EEPROM data. */
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unsigned address;
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eeprom_t *eeprom = (eeprom_t *)opaque; |
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qemu_put_buffer(f, (uint8_t *)eeprom, sizeof(*eeprom) - 2); |
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qemu_put_be16(f, eeprom->data); |
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for (address = 0; address < eeprom->size; address++) { |
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qemu_put_be16(f, eeprom->contents[address]); |
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} |
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} |
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static int eeprom_load(QEMUFile *f, void *opaque, int version_id) |
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{ |
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/* Load EEPROM data from saved data if version and EEPROM size
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of data and current EEPROM are identical. */
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eeprom_t *eeprom = (eeprom_t *)opaque; |
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int result = -EINVAL;
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if (version_id == eeprom_version) {
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unsigned address;
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uint8_t size = eeprom->size; |
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qemu_get_buffer(f, (uint8_t *)eeprom, sizeof(*eeprom) - 2); |
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if (eeprom->size == size) {
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eeprom->data = qemu_get_be16(f); |
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for (address = 0; address < eeprom->size; address++) { |
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eeprom->contents[address] = qemu_get_be16(f); |
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} |
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result = 0;
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} |
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} |
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return result;
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} |
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void eeprom93xx_write(eeprom_t *eeprom, int eecs, int eesk, int eedi) |
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{ |
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uint8_t tick = eeprom->tick; |
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uint8_t eedo = eeprom->eedo; |
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uint16_t address = eeprom->address; |
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uint8_t command = eeprom->command; |
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logout("CS=%u SK=%u DI=%u DO=%u, tick = %u\n",
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eecs, eesk, eedi, eedo, tick); |
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if (! eeprom->eecs && eecs) {
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/* Start chip select cycle. */
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logout("Cycle start, waiting for 1st start bit (0)\n");
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tick = 0;
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command = 0x0;
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address = 0x0;
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} else if (eeprom->eecs && ! eecs) { |
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/* End chip select cycle. This triggers write / erase. */
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if (eeprom->writeable) {
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uint8_t subcommand = address >> (eeprom->addrbits - 2);
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if (command == 0 && subcommand == 2) { |
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/* Erase all. */
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for (address = 0; address < eeprom->size; address++) { |
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eeprom->contents[address] = 0xffff;
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} |
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} else if (command == 3) { |
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/* Erase word. */
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eeprom->contents[address] = 0xffff;
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} else if (tick >= 2 + 2 + eeprom->addrbits + 16) { |
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if (command == 1) { |
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/* Write word. */
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eeprom->contents[address] &= eeprom->data; |
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} else if (command == 0 && subcommand == 1) { |
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/* Write all. */
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for (address = 0; address < eeprom->size; address++) { |
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eeprom->contents[address] &= eeprom->data; |
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} |
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} |
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} |
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} |
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/* Output DO is tristate, read results in 1. */
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eedo = 1;
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} else if (eecs && ! eeprom->eesk && eesk) { |
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/* Raising edge of clock shifts data in. */
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if (tick == 0) { |
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/* Wait for 1st start bit. */
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if (eedi == 0) { |
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logout("Got correct 1st start bit, waiting for 2nd start bit (1)\n");
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tick++; |
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} else {
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logout("wrong 1st start bit (is 1, should be 0)\n");
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tick = 2;
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//~ assert(!"wrong start bit");
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} |
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} else if (tick == 1) { |
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/* Wait for 2nd start bit. */
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if (eedi != 0) { |
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logout("Got correct 2nd start bit, getting command + address\n");
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tick++; |
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} else {
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logout("1st start bit is longer than needed\n");
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} |
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} else if (tick < 2 + 2) { |
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/* Got 2 start bits, transfer 2 opcode bits. */
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tick++; |
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command <<= 1;
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if (eedi) {
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command += 1;
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} |
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} else if (tick < 2 + 2 + eeprom->addrbits) { |
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/* Got 2 start bits and 2 opcode bits, transfer all address bits. */
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tick++; |
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address = ((address << 1) | eedi);
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if (tick == 2 + 2 + eeprom->addrbits) { |
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logout("%s command, address = 0x%02x (value 0x%04x)\n",
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opstring[command], address, eeprom->contents[address]); |
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if (command == 2) { |
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eedo = 0;
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} |
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address = address % eeprom->size; |
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if (command == 0) { |
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/* Command code in upper 2 bits of address. */
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switch (address >> (eeprom->addrbits - 2)) { |
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case 0: |
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logout("write disable command\n");
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eeprom->writeable = 0;
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break;
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case 1: |
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logout("write all command\n");
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break;
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case 2: |
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logout("erase all command\n");
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break;
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case 3: |
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logout("write enable command\n");
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eeprom->writeable = 1;
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break;
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} |
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} else {
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/* Read, write or erase word. */
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eeprom->data = eeprom->contents[address]; |
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} |
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} |
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} else if (tick < 2 + 2 + eeprom->addrbits + 16) { |
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/* Transfer 16 data bits. */
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tick++; |
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if (command == 2) { |
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/* Read word. */
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eedo = ((eeprom->data & 0x8000) != 0); |
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} |
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eeprom->data <<= 1;
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eeprom->data += eedi; |
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} else {
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logout("additional unneeded tick, not processed\n");
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} |
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} |
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/* Save status of EEPROM. */
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eeprom->tick = tick; |
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eeprom->eecs = eecs; |
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eeprom->eesk = eesk; |
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eeprom->eedo = eedo; |
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eeprom->address = address; |
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eeprom->command = command; |
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} |
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uint16_t eeprom93xx_read(eeprom_t *eeprom) |
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{ |
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/* Return status of pin DO (0 or 1). */
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logout("CS=%u DO=%u\n", eeprom->eecs, eeprom->eedo);
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return (eeprom->eedo);
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} |
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#if 0
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void eeprom93xx_reset(eeprom_t *eeprom)
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{
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/* prepare eeprom */
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logout("eeprom = 0x%p\n", eeprom);
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eeprom->tick = 0;
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eeprom->command = 0;
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}
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#endif
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eeprom_t *eeprom93xx_new(uint16_t nwords) |
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{ |
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/* Add a new EEPROM (with 16, 64 or 256 words). */
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eeprom_t *eeprom; |
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uint8_t addrbits; |
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switch (nwords) {
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case 16: |
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case 64: |
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addrbits = 6;
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break;
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case 128: |
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case 256: |
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addrbits = 8;
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break;
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default:
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assert(!"Unsupported EEPROM size, fallback to 64 words!");
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nwords = 64;
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addrbits = 6;
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} |
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eeprom = (eeprom_t *)qemu_mallocz(sizeof(*eeprom) + nwords * 2); |
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eeprom->size = nwords; |
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eeprom->addrbits = addrbits; |
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/* Output DO is tristate, read results in 1. */
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eeprom->eedo = 1;
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logout("eeprom = 0x%p, nwords = %u\n", eeprom, nwords);
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register_savevm("eeprom", eeprom_instance, eeprom_version,
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eeprom_save, eeprom_load, eeprom); |
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return eeprom;
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} |
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void eeprom93xx_free(eeprom_t *eeprom)
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{ |
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/* Destroy EEPROM. */
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logout("eeprom = 0x%p\n", eeprom);
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qemu_free(eeprom); |
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} |
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uint16_t *eeprom93xx_data(eeprom_t *eeprom) |
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{ |
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/* Get EEPROM data array. */
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return &eeprom->contents[0]; |
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} |
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/* eof */
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