2 * QEMU EEPROM 93xx emulation
4 * Copyright (c) 2006-2007 Stefan Weil
6 * This program is free software; you can redistribute it and/or modify
7 * it under the terms of the GNU General Public License as published by
8 * the Free Software Foundation; either version 2 of the License, or
9 * (at your option) any later version.
11 * This program is distributed in the hope that it will be useful,
12 * but WITHOUT ANY WARRANTY; without even the implied warranty of
13 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14 * GNU General Public License for more details.
16 * You should have received a copy of the GNU General Public License
17 * along with this program; if not, write to the Free Software
18 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
21 /* Emulation for serial EEPROMs:
22 * NMC93C06 256-Bit (16 x 16)
23 * NMC93C46 1024-Bit (64 x 16)
24 * NMC93C56 2028 Bit (128 x 16)
25 * NMC93C66 4096 Bit (256 x 16)
26 * Compatible devices include FM93C46 and others.
28 * Other drivers use these interface functions:
29 * eeprom93xx_new - add a new EEPROM (with 16, 64 or 256 words)
30 * eeprom93xx_free - destroy EEPROM
31 * eeprom93xx_read - read data from the EEPROM
32 * eeprom93xx_write - write data to the EEPROM
33 * eeprom93xx_data - get EEPROM data array for external manipulation
36 * - No emulation of EEPROM timings.
41 #include "eeprom93xx.h"
43 /* Debug EEPROM emulation. */
44 //~ #define DEBUG_EEPROM
47 #define logout(fmt, args...) fprintf(stderr, "EEPROM\t%-24s" fmt, __func__, ##args)
49 #define logout(fmt, args...) ((void)0)
52 static int eeprom_instance = 0;
53 static const int eeprom_version = 20061112;
57 eeprom_read = 0x80, /* read register xx */
58 eeprom_write = 0x40, /* write register xx */
59 eeprom_erase = 0xc0, /* erase register xx */
60 eeprom_ewen = 0x30, /* erase / write enable */
61 eeprom_ewds = 0x00, /* erase / write disable */
62 eeprom_eral = 0x20, /* erase all registers */
63 eeprom_wral = 0x10, /* write all registers */
66 } eeprom_instruction_t;
70 static const char *opstring[] = {
71 "extended", "write", "read", "erase"
91 /* Code for saving and restoring of EEPROM state. */
93 static void eeprom_save(QEMUFile *f, void *opaque)
95 /* Save EEPROM data. */
97 eeprom_t *eeprom = (eeprom_t *)opaque;
99 qemu_put_byte(f, eeprom->tick);
100 qemu_put_byte(f, eeprom->address);
101 qemu_put_byte(f, eeprom->command);
102 qemu_put_byte(f, eeprom->writeable);
104 qemu_put_byte(f, eeprom->eecs);
105 qemu_put_byte(f, eeprom->eesk);
106 qemu_put_byte(f, eeprom->eedo);
108 qemu_put_byte(f, eeprom->addrbits);
109 qemu_put_byte(f, eeprom->size);
110 qemu_put_byte(f, 0); /* padding for compatiblity */
111 qemu_put_be16(f, eeprom->data);
112 for (address = 0; address < eeprom->size; address++) {
113 qemu_put_be16(f, eeprom->contents[address]);
117 static int eeprom_load(QEMUFile *f, void *opaque, int version_id)
119 /* Load EEPROM data from saved data if version and EEPROM size
120 of data and current EEPROM are identical. */
121 eeprom_t *eeprom = (eeprom_t *)opaque;
122 int result = -EINVAL;
123 if (version_id == eeprom_version) {
125 uint8_t size = eeprom->size;
127 eeprom->tick = qemu_get_byte(f);
128 eeprom->address = qemu_get_byte(f);
129 eeprom->command = qemu_get_byte(f);
130 eeprom->writeable = qemu_get_byte(f);
132 eeprom->eecs = qemu_get_byte(f);
133 eeprom->eesk = qemu_get_byte(f);
134 eeprom->eedo = qemu_get_byte(f);
136 eeprom->addrbits = qemu_get_byte(f);
137 eeprom->size = qemu_get_byte(f);
138 qemu_get_byte(f); /* skip padding byte */
140 if (eeprom->size == size) {
141 eeprom->data = qemu_get_be16(f);
142 for (address = 0; address < eeprom->size; address++) {
143 eeprom->contents[address] = qemu_get_be16(f);
151 void eeprom93xx_write(eeprom_t *eeprom, int eecs, int eesk, int eedi)
153 uint8_t tick = eeprom->tick;
154 uint8_t eedo = eeprom->eedo;
155 uint16_t address = eeprom->address;
156 uint8_t command = eeprom->command;
158 logout("CS=%u SK=%u DI=%u DO=%u, tick = %u\n",
159 eecs, eesk, eedi, eedo, tick);
161 if (! eeprom->eecs && eecs) {
162 /* Start chip select cycle. */
163 logout("Cycle start, waiting for 1st start bit (0)\n");
167 } else if (eeprom->eecs && ! eecs) {
168 /* End chip select cycle. This triggers write / erase. */
169 if (eeprom->writeable) {
170 uint8_t subcommand = address >> (eeprom->addrbits - 2);
171 if (command == 0 && subcommand == 2) {
173 for (address = 0; address < eeprom->size; address++) {
174 eeprom->contents[address] = 0xffff;
176 } else if (command == 3) {
178 eeprom->contents[address] = 0xffff;
179 } else if (tick >= 2 + 2 + eeprom->addrbits + 16) {
182 eeprom->contents[address] &= eeprom->data;
183 } else if (command == 0 && subcommand == 1) {
185 for (address = 0; address < eeprom->size; address++) {
186 eeprom->contents[address] &= eeprom->data;
191 /* Output DO is tristate, read results in 1. */
193 } else if (eecs && ! eeprom->eesk && eesk) {
194 /* Raising edge of clock shifts data in. */
196 /* Wait for 1st start bit. */
198 logout("Got correct 1st start bit, waiting for 2nd start bit (1)\n");
201 logout("wrong 1st start bit (is 1, should be 0)\n");
203 //~ assert(!"wrong start bit");
205 } else if (tick == 1) {
206 /* Wait for 2nd start bit. */
208 logout("Got correct 2nd start bit, getting command + address\n");
211 logout("1st start bit is longer than needed\n");
213 } else if (tick < 2 + 2) {
214 /* Got 2 start bits, transfer 2 opcode bits. */
220 } else if (tick < 2 + 2 + eeprom->addrbits) {
221 /* Got 2 start bits and 2 opcode bits, transfer all address bits. */
223 address = ((address << 1) | eedi);
224 if (tick == 2 + 2 + eeprom->addrbits) {
225 logout("%s command, address = 0x%02x (value 0x%04x)\n",
226 opstring[command], address, eeprom->contents[address]);
230 address = address % eeprom->size;
232 /* Command code in upper 2 bits of address. */
233 switch (address >> (eeprom->addrbits - 2)) {
235 logout("write disable command\n");
236 eeprom->writeable = 0;
239 logout("write all command\n");
242 logout("erase all command\n");
245 logout("write enable command\n");
246 eeprom->writeable = 1;
250 /* Read, write or erase word. */
251 eeprom->data = eeprom->contents[address];
254 } else if (tick < 2 + 2 + eeprom->addrbits + 16) {
255 /* Transfer 16 data bits. */
259 eedo = ((eeprom->data & 0x8000) != 0);
262 eeprom->data += eedi;
264 logout("additional unneeded tick, not processed\n");
267 /* Save status of EEPROM. */
272 eeprom->address = address;
273 eeprom->command = command;
276 uint16_t eeprom93xx_read(eeprom_t *eeprom)
278 /* Return status of pin DO (0 or 1). */
279 logout("CS=%u DO=%u\n", eeprom->eecs, eeprom->eedo);
280 return (eeprom->eedo);
284 void eeprom93xx_reset(eeprom_t *eeprom)
287 logout("eeprom = 0x%p\n", eeprom);
293 eeprom_t *eeprom93xx_new(uint16_t nwords)
295 /* Add a new EEPROM (with 16, 64 or 256 words). */
309 assert(!"Unsupported EEPROM size, fallback to 64 words!");
314 eeprom = (eeprom_t *)qemu_mallocz(sizeof(*eeprom) + nwords * 2);
315 eeprom->size = nwords;
316 eeprom->addrbits = addrbits;
317 /* Output DO is tristate, read results in 1. */
319 logout("eeprom = 0x%p, nwords = %u\n", eeprom, nwords);
320 register_savevm("eeprom", eeprom_instance, eeprom_version,
321 eeprom_save, eeprom_load, eeprom);
325 void eeprom93xx_free(eeprom_t *eeprom)
327 /* Destroy EEPROM. */
328 logout("eeprom = 0x%p\n", eeprom);
332 uint16_t *eeprom93xx_data(eeprom_t *eeprom)
334 /* Get EEPROM data array. */
335 return &eeprom->contents[0];