1 /* 2 * QEMU EEPROM 93xx emulation 3 * 4 * Copyright (c) 2006-2007 Stefan Weil 5 * 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. 10 * 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. 15 * 16 * You should have received a copy of the GNU General Public License 17 * along with this program; if not, see <http://www.gnu.org/licenses/>. 18 */ 19 20 /* Emulation for serial EEPROMs: 21 * NMC93C06 256-Bit (16 x 16) 22 * NMC93C46 1024-Bit (64 x 16) 23 * NMC93C56 2028 Bit (128 x 16) 24 * NMC93C66 4096 Bit (256 x 16) 25 * Compatible devices include FM93C46 and others. 26 * 27 * Other drivers use these interface functions: 28 * eeprom93xx_new - add a new EEPROM (with 16, 64 or 256 words) 29 * eeprom93xx_free - destroy EEPROM 30 * eeprom93xx_read - read data from the EEPROM 31 * eeprom93xx_write - write data to the EEPROM 32 * eeprom93xx_data - get EEPROM data array for external manipulation 33 * 34 * Todo list: 35 * - No emulation of EEPROM timings. 36 */ 37 38 #include "hw/hw.h" 39 #include "hw/nvram/eeprom93xx.h" 40 41 /* Debug EEPROM emulation. */ 42 //~ #define DEBUG_EEPROM 43 44 #ifdef DEBUG_EEPROM 45 #define logout(fmt, ...) fprintf(stderr, "EEPROM\t%-24s" fmt, __func__, ## __VA_ARGS__) 46 #else 47 #define logout(fmt, ...) ((void)0) 48 #endif 49 50 #define EEPROM_INSTANCE 0 51 #define OLD_EEPROM_VERSION 20061112 52 #define EEPROM_VERSION (OLD_EEPROM_VERSION + 1) 53 54 #if 0 55 typedef enum { 56 eeprom_read = 0x80, /* read register xx */ 57 eeprom_write = 0x40, /* write register xx */ 58 eeprom_erase = 0xc0, /* erase register xx */ 59 eeprom_ewen = 0x30, /* erase / write enable */ 60 eeprom_ewds = 0x00, /* erase / write disable */ 61 eeprom_eral = 0x20, /* erase all registers */ 62 eeprom_wral = 0x10, /* write all registers */ 63 eeprom_amask = 0x0f, 64 eeprom_imask = 0xf0 65 } eeprom_instruction_t; 66 #endif 67 68 #ifdef DEBUG_EEPROM 69 static const char *opstring[] = { 70 "extended", "write", "read", "erase" 71 }; 72 #endif 73 74 struct _eeprom_t { 75 uint8_t tick; 76 uint8_t address; 77 uint8_t command; 78 uint8_t writable; 79 80 uint8_t eecs; 81 uint8_t eesk; 82 uint8_t eedo; 83 84 uint8_t addrbits; 85 uint16_t size; 86 uint16_t data; 87 uint16_t contents[0]; 88 }; 89 90 /* Code for saving and restoring of EEPROM state. */ 91 92 /* Restore an uint16_t from an uint8_t 93 This is a Big hack, but it is how the old state did it. 94 */ 95 96 static int get_uint16_from_uint8(QEMUFile *f, void *pv, size_t size) 97 { 98 uint16_t *v = pv; 99 *v = qemu_get_ubyte(f); 100 return 0; 101 } 102 103 static void put_unused(QEMUFile *f, void *pv, size_t size) 104 { 105 fprintf(stderr, "uint16_from_uint8 is used only for backwards compatibility.\n"); 106 fprintf(stderr, "Never should be used to write a new state.\n"); 107 exit(0); 108 } 109 110 static const VMStateInfo vmstate_hack_uint16_from_uint8 = { 111 .name = "uint16_from_uint8", 112 .get = get_uint16_from_uint8, 113 .put = put_unused, 114 }; 115 116 #define VMSTATE_UINT16_HACK_TEST(_f, _s, _t) \ 117 VMSTATE_SINGLE_TEST(_f, _s, _t, 0, vmstate_hack_uint16_from_uint8, uint16_t) 118 119 static bool is_old_eeprom_version(void *opaque, int version_id) 120 { 121 return version_id == OLD_EEPROM_VERSION; 122 } 123 124 static const VMStateDescription vmstate_eeprom = { 125 .name = "eeprom", 126 .version_id = EEPROM_VERSION, 127 .minimum_version_id = OLD_EEPROM_VERSION, 128 .minimum_version_id_old = OLD_EEPROM_VERSION, 129 .fields = (VMStateField[]) { 130 VMSTATE_UINT8(tick, eeprom_t), 131 VMSTATE_UINT8(address, eeprom_t), 132 VMSTATE_UINT8(command, eeprom_t), 133 VMSTATE_UINT8(writable, eeprom_t), 134 135 VMSTATE_UINT8(eecs, eeprom_t), 136 VMSTATE_UINT8(eesk, eeprom_t), 137 VMSTATE_UINT8(eedo, eeprom_t), 138 139 VMSTATE_UINT8(addrbits, eeprom_t), 140 VMSTATE_UINT16_HACK_TEST(size, eeprom_t, is_old_eeprom_version), 141 VMSTATE_UNUSED_TEST(is_old_eeprom_version, 1), 142 VMSTATE_UINT16_EQUAL_V(size, eeprom_t, EEPROM_VERSION), 143 VMSTATE_UINT16(data, eeprom_t), 144 VMSTATE_VARRAY_UINT16_UNSAFE(contents, eeprom_t, size, 0, 145 vmstate_info_uint16, uint16_t), 146 VMSTATE_END_OF_LIST() 147 } 148 }; 149 150 void eeprom93xx_write(eeprom_t *eeprom, int eecs, int eesk, int eedi) 151 { 152 uint8_t tick = eeprom->tick; 153 uint8_t eedo = eeprom->eedo; 154 uint16_t address = eeprom->address; 155 uint8_t command = eeprom->command; 156 157 logout("CS=%u SK=%u DI=%u DO=%u, tick = %u\n", 158 eecs, eesk, eedi, eedo, tick); 159 160 if (!eeprom->eecs && eecs) { 161 /* Start chip select cycle. */ 162 logout("Cycle start, waiting for 1st start bit (0)\n"); 163 tick = 0; 164 command = 0x0; 165 address = 0x0; 166 } else if (eeprom->eecs && !eecs) { 167 /* End chip select cycle. This triggers write / erase. */ 168 if (eeprom->writable) { 169 uint8_t subcommand = address >> (eeprom->addrbits - 2); 170 if (command == 0 && subcommand == 2) { 171 /* Erase all. */ 172 for (address = 0; address < eeprom->size; address++) { 173 eeprom->contents[address] = 0xffff; 174 } 175 } else if (command == 3) { 176 /* Erase word. */ 177 eeprom->contents[address] = 0xffff; 178 } else if (tick >= 2 + 2 + eeprom->addrbits + 16) { 179 if (command == 1) { 180 /* Write word. */ 181 eeprom->contents[address] &= eeprom->data; 182 } else if (command == 0 && subcommand == 1) { 183 /* Write all. */ 184 for (address = 0; address < eeprom->size; address++) { 185 eeprom->contents[address] &= eeprom->data; 186 } 187 } 188 } 189 } 190 /* Output DO is tristate, read results in 1. */ 191 eedo = 1; 192 } else if (eecs && !eeprom->eesk && eesk) { 193 /* Raising edge of clock shifts data in. */ 194 if (tick == 0) { 195 /* Wait for 1st start bit. */ 196 if (eedi == 0) { 197 logout("Got correct 1st start bit, waiting for 2nd start bit (1)\n"); 198 tick++; 199 } else { 200 logout("wrong 1st start bit (is 1, should be 0)\n"); 201 tick = 2; 202 //~ assert(!"wrong start bit"); 203 } 204 } else if (tick == 1) { 205 /* Wait for 2nd start bit. */ 206 if (eedi != 0) { 207 logout("Got correct 2nd start bit, getting command + address\n"); 208 tick++; 209 } else { 210 logout("1st start bit is longer than needed\n"); 211 } 212 } else if (tick < 2 + 2) { 213 /* Got 2 start bits, transfer 2 opcode bits. */ 214 tick++; 215 command <<= 1; 216 if (eedi) { 217 command += 1; 218 } 219 } else if (tick < 2 + 2 + eeprom->addrbits) { 220 /* Got 2 start bits and 2 opcode bits, transfer all address bits. */ 221 tick++; 222 address = ((address << 1) | eedi); 223 if (tick == 2 + 2 + eeprom->addrbits) { 224 logout("%s command, address = 0x%02x (value 0x%04x)\n", 225 opstring[command], address, eeprom->contents[address]); 226 if (command == 2) { 227 eedo = 0; 228 } 229 address = address % eeprom->size; 230 if (command == 0) { 231 /* Command code in upper 2 bits of address. */ 232 switch (address >> (eeprom->addrbits - 2)) { 233 case 0: 234 logout("write disable command\n"); 235 eeprom->writable = 0; 236 break; 237 case 1: 238 logout("write all command\n"); 239 break; 240 case 2: 241 logout("erase all command\n"); 242 break; 243 case 3: 244 logout("write enable command\n"); 245 eeprom->writable = 1; 246 break; 247 } 248 } else { 249 /* Read, write or erase word. */ 250 eeprom->data = eeprom->contents[address]; 251 } 252 } 253 } else if (tick < 2 + 2 + eeprom->addrbits + 16) { 254 /* Transfer 16 data bits. */ 255 tick++; 256 if (command == 2) { 257 /* Read word. */ 258 eedo = ((eeprom->data & 0x8000) != 0); 259 } 260 eeprom->data <<= 1; 261 eeprom->data += eedi; 262 } else { 263 logout("additional unneeded tick, not processed\n"); 264 } 265 } 266 /* Save status of EEPROM. */ 267 eeprom->tick = tick; 268 eeprom->eecs = eecs; 269 eeprom->eesk = eesk; 270 eeprom->eedo = eedo; 271 eeprom->address = address; 272 eeprom->command = command; 273 } 274 275 uint16_t eeprom93xx_read(eeprom_t *eeprom) 276 { 277 /* Return status of pin DO (0 or 1). */ 278 logout("CS=%u DO=%u\n", eeprom->eecs, eeprom->eedo); 279 return eeprom->eedo; 280 } 281 282 #if 0 283 void eeprom93xx_reset(eeprom_t *eeprom) 284 { 285 /* prepare eeprom */ 286 logout("eeprom = 0x%p\n", eeprom); 287 eeprom->tick = 0; 288 eeprom->command = 0; 289 } 290 #endif 291 292 eeprom_t *eeprom93xx_new(DeviceState *dev, uint16_t nwords) 293 { 294 /* Add a new EEPROM (with 16, 64 or 256 words). */ 295 eeprom_t *eeprom; 296 uint8_t addrbits; 297 298 switch (nwords) { 299 case 16: 300 case 64: 301 addrbits = 6; 302 break; 303 case 128: 304 case 256: 305 addrbits = 8; 306 break; 307 default: 308 assert(!"Unsupported EEPROM size, fallback to 64 words!"); 309 nwords = 64; 310 addrbits = 6; 311 } 312 313 eeprom = (eeprom_t *)g_malloc0(sizeof(*eeprom) + nwords * 2); 314 eeprom->size = nwords; 315 eeprom->addrbits = addrbits; 316 /* Output DO is tristate, read results in 1. */ 317 eeprom->eedo = 1; 318 logout("eeprom = 0x%p, nwords = %u\n", eeprom, nwords); 319 vmstate_register(dev, 0, &vmstate_eeprom, eeprom); 320 return eeprom; 321 } 322 323 void eeprom93xx_free(DeviceState *dev, eeprom_t *eeprom) 324 { 325 /* Destroy EEPROM. */ 326 logout("eeprom = 0x%p\n", eeprom); 327 vmstate_unregister(dev, &vmstate_eeprom, eeprom); 328 g_free(eeprom); 329 } 330 331 uint16_t *eeprom93xx_data(eeprom_t *eeprom) 332 { 333 /* Get EEPROM data array. */ 334 return &eeprom->contents[0]; 335 } 336 337 /* eof */ 338