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 "qemu/osdep.h" 39 #include "hw/hw.h" 40 #include "hw/nvram/eeprom93xx.h" 41 42 /* Debug EEPROM emulation. */ 43 //~ #define DEBUG_EEPROM 44 45 #ifdef DEBUG_EEPROM 46 #define logout(fmt, ...) fprintf(stderr, "EEPROM\t%-24s" fmt, __func__, ## __VA_ARGS__) 47 #else 48 #define logout(fmt, ...) ((void)0) 49 #endif 50 51 #define EEPROM_INSTANCE 0 52 #define OLD_EEPROM_VERSION 20061112 53 #define EEPROM_VERSION (OLD_EEPROM_VERSION + 1) 54 55 #if 0 56 typedef enum { 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 */ 64 eeprom_amask = 0x0f, 65 eeprom_imask = 0xf0 66 } eeprom_instruction_t; 67 #endif 68 69 #ifdef DEBUG_EEPROM 70 static const char *opstring[] = { 71 "extended", "write", "read", "erase" 72 }; 73 #endif 74 75 struct _eeprom_t { 76 uint8_t tick; 77 uint8_t address; 78 uint8_t command; 79 uint8_t writable; 80 81 uint8_t eecs; 82 uint8_t eesk; 83 uint8_t eedo; 84 85 uint8_t addrbits; 86 uint16_t size; 87 uint16_t data; 88 uint16_t contents[0]; 89 }; 90 91 /* Code for saving and restoring of EEPROM state. */ 92 93 /* Restore an uint16_t from an uint8_t 94 This is a Big hack, but it is how the old state did it. 95 */ 96 97 static int get_uint16_from_uint8(QEMUFile *f, void *pv, size_t size, 98 VMStateField *field) 99 { 100 uint16_t *v = pv; 101 *v = qemu_get_ubyte(f); 102 return 0; 103 } 104 105 static int put_unused(QEMUFile *f, void *pv, size_t size, VMStateField *field, 106 QJSON *vmdesc) 107 { 108 fprintf(stderr, "uint16_from_uint8 is used only for backwards compatibility.\n"); 109 fprintf(stderr, "Never should be used to write a new state.\n"); 110 exit(0); 111 112 return 0; 113 } 114 115 static const VMStateInfo vmstate_hack_uint16_from_uint8 = { 116 .name = "uint16_from_uint8", 117 .get = get_uint16_from_uint8, 118 .put = put_unused, 119 }; 120 121 #define VMSTATE_UINT16_HACK_TEST(_f, _s, _t) \ 122 VMSTATE_SINGLE_TEST(_f, _s, _t, 0, vmstate_hack_uint16_from_uint8, uint16_t) 123 124 static bool is_old_eeprom_version(void *opaque, int version_id) 125 { 126 return version_id == OLD_EEPROM_VERSION; 127 } 128 129 static const VMStateDescription vmstate_eeprom = { 130 .name = "eeprom", 131 .version_id = EEPROM_VERSION, 132 .minimum_version_id = OLD_EEPROM_VERSION, 133 .fields = (VMStateField[]) { 134 VMSTATE_UINT8(tick, eeprom_t), 135 VMSTATE_UINT8(address, eeprom_t), 136 VMSTATE_UINT8(command, eeprom_t), 137 VMSTATE_UINT8(writable, eeprom_t), 138 139 VMSTATE_UINT8(eecs, eeprom_t), 140 VMSTATE_UINT8(eesk, eeprom_t), 141 VMSTATE_UINT8(eedo, eeprom_t), 142 143 VMSTATE_UINT8(addrbits, eeprom_t), 144 VMSTATE_UINT16_HACK_TEST(size, eeprom_t, is_old_eeprom_version), 145 VMSTATE_UNUSED_TEST(is_old_eeprom_version, 1), 146 VMSTATE_UINT16_EQUAL_V(size, eeprom_t, EEPROM_VERSION), 147 VMSTATE_UINT16(data, eeprom_t), 148 VMSTATE_VARRAY_UINT16_UNSAFE(contents, eeprom_t, size, 0, 149 vmstate_info_uint16, uint16_t), 150 VMSTATE_END_OF_LIST() 151 } 152 }; 153 154 void eeprom93xx_write(eeprom_t *eeprom, int eecs, int eesk, int eedi) 155 { 156 uint8_t tick = eeprom->tick; 157 uint8_t eedo = eeprom->eedo; 158 uint16_t address = eeprom->address; 159 uint8_t command = eeprom->command; 160 161 logout("CS=%u SK=%u DI=%u DO=%u, tick = %u\n", 162 eecs, eesk, eedi, eedo, tick); 163 164 if (!eeprom->eecs && eecs) { 165 /* Start chip select cycle. */ 166 logout("Cycle start, waiting for 1st start bit (0)\n"); 167 tick = 0; 168 command = 0x0; 169 address = 0x0; 170 } else if (eeprom->eecs && !eecs) { 171 /* End chip select cycle. This triggers write / erase. */ 172 if (eeprom->writable) { 173 uint8_t subcommand = address >> (eeprom->addrbits - 2); 174 if (command == 0 && subcommand == 2) { 175 /* Erase all. */ 176 for (address = 0; address < eeprom->size; address++) { 177 eeprom->contents[address] = 0xffff; 178 } 179 } else if (command == 3) { 180 /* Erase word. */ 181 eeprom->contents[address] = 0xffff; 182 } else if (tick >= 2 + 2 + eeprom->addrbits + 16) { 183 if (command == 1) { 184 /* Write word. */ 185 eeprom->contents[address] &= eeprom->data; 186 } else if (command == 0 && subcommand == 1) { 187 /* Write all. */ 188 for (address = 0; address < eeprom->size; address++) { 189 eeprom->contents[address] &= eeprom->data; 190 } 191 } 192 } 193 } 194 /* Output DO is tristate, read results in 1. */ 195 eedo = 1; 196 } else if (eecs && !eeprom->eesk && eesk) { 197 /* Raising edge of clock shifts data in. */ 198 if (tick == 0) { 199 /* Wait for 1st start bit. */ 200 if (eedi == 0) { 201 logout("Got correct 1st start bit, waiting for 2nd start bit (1)\n"); 202 tick++; 203 } else { 204 logout("wrong 1st start bit (is 1, should be 0)\n"); 205 tick = 2; 206 //~ assert(!"wrong start bit"); 207 } 208 } else if (tick == 1) { 209 /* Wait for 2nd start bit. */ 210 if (eedi != 0) { 211 logout("Got correct 2nd start bit, getting command + address\n"); 212 tick++; 213 } else { 214 logout("1st start bit is longer than needed\n"); 215 } 216 } else if (tick < 2 + 2) { 217 /* Got 2 start bits, transfer 2 opcode bits. */ 218 tick++; 219 command <<= 1; 220 if (eedi) { 221 command += 1; 222 } 223 } else if (tick < 2 + 2 + eeprom->addrbits) { 224 /* Got 2 start bits and 2 opcode bits, transfer all address bits. */ 225 tick++; 226 address = ((address << 1) | eedi); 227 if (tick == 2 + 2 + eeprom->addrbits) { 228 logout("%s command, address = 0x%02x (value 0x%04x)\n", 229 opstring[command], address, eeprom->contents[address]); 230 if (command == 2) { 231 eedo = 0; 232 } 233 address = address % eeprom->size; 234 if (command == 0) { 235 /* Command code in upper 2 bits of address. */ 236 switch (address >> (eeprom->addrbits - 2)) { 237 case 0: 238 logout("write disable command\n"); 239 eeprom->writable = 0; 240 break; 241 case 1: 242 logout("write all command\n"); 243 break; 244 case 2: 245 logout("erase all command\n"); 246 break; 247 case 3: 248 logout("write enable command\n"); 249 eeprom->writable = 1; 250 break; 251 } 252 } else { 253 /* Read, write or erase word. */ 254 eeprom->data = eeprom->contents[address]; 255 } 256 } 257 } else if (tick < 2 + 2 + eeprom->addrbits + 16) { 258 /* Transfer 16 data bits. */ 259 tick++; 260 if (command == 2) { 261 /* Read word. */ 262 eedo = ((eeprom->data & 0x8000) != 0); 263 } 264 eeprom->data <<= 1; 265 eeprom->data += eedi; 266 } else { 267 logout("additional unneeded tick, not processed\n"); 268 } 269 } 270 /* Save status of EEPROM. */ 271 eeprom->tick = tick; 272 eeprom->eecs = eecs; 273 eeprom->eesk = eesk; 274 eeprom->eedo = eedo; 275 eeprom->address = address; 276 eeprom->command = command; 277 } 278 279 uint16_t eeprom93xx_read(eeprom_t *eeprom) 280 { 281 /* Return status of pin DO (0 or 1). */ 282 logout("CS=%u DO=%u\n", eeprom->eecs, eeprom->eedo); 283 return eeprom->eedo; 284 } 285 286 #if 0 287 void eeprom93xx_reset(eeprom_t *eeprom) 288 { 289 /* prepare eeprom */ 290 logout("eeprom = 0x%p\n", eeprom); 291 eeprom->tick = 0; 292 eeprom->command = 0; 293 } 294 #endif 295 296 eeprom_t *eeprom93xx_new(DeviceState *dev, uint16_t nwords) 297 { 298 /* Add a new EEPROM (with 16, 64 or 256 words). */ 299 eeprom_t *eeprom; 300 uint8_t addrbits; 301 302 switch (nwords) { 303 case 16: 304 case 64: 305 addrbits = 6; 306 break; 307 case 128: 308 case 256: 309 addrbits = 8; 310 break; 311 default: 312 assert(!"Unsupported EEPROM size, fallback to 64 words!"); 313 nwords = 64; 314 addrbits = 6; 315 } 316 317 eeprom = (eeprom_t *)g_malloc0(sizeof(*eeprom) + nwords * 2); 318 eeprom->size = nwords; 319 eeprom->addrbits = addrbits; 320 /* Output DO is tristate, read results in 1. */ 321 eeprom->eedo = 1; 322 logout("eeprom = 0x%p, nwords = %u\n", eeprom, nwords); 323 vmstate_register(dev, 0, &vmstate_eeprom, eeprom); 324 return eeprom; 325 } 326 327 void eeprom93xx_free(DeviceState *dev, eeprom_t *eeprom) 328 { 329 /* Destroy EEPROM. */ 330 logout("eeprom = 0x%p\n", eeprom); 331 vmstate_unregister(dev, &vmstate_eeprom, eeprom); 332 g_free(eeprom); 333 } 334 335 uint16_t *eeprom93xx_data(eeprom_t *eeprom) 336 { 337 /* Get EEPROM data array. */ 338 return &eeprom->contents[0]; 339 } 340 341 /* eof */ 342