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 #include "migration/qemu-file-types.h" 42 #include "migration/vmstate.h" 43 44 /* Debug EEPROM emulation. */ 45 //~ #define DEBUG_EEPROM 46 47 #ifdef DEBUG_EEPROM 48 #define logout(fmt, ...) fprintf(stderr, "EEPROM\t%-24s" fmt, __func__, ## __VA_ARGS__) 49 #else 50 #define logout(fmt, ...) ((void)0) 51 #endif 52 53 #define EEPROM_INSTANCE 0 54 #define OLD_EEPROM_VERSION 20061112 55 #define EEPROM_VERSION (OLD_EEPROM_VERSION + 1) 56 57 #if 0 58 typedef enum { 59 eeprom_read = 0x80, /* read register xx */ 60 eeprom_write = 0x40, /* write register xx */ 61 eeprom_erase = 0xc0, /* erase register xx */ 62 eeprom_ewen = 0x30, /* erase / write enable */ 63 eeprom_ewds = 0x00, /* erase / write disable */ 64 eeprom_eral = 0x20, /* erase all registers */ 65 eeprom_wral = 0x10, /* write all registers */ 66 eeprom_amask = 0x0f, 67 eeprom_imask = 0xf0 68 } eeprom_instruction_t; 69 #endif 70 71 #ifdef DEBUG_EEPROM 72 static const char *opstring[] = { 73 "extended", "write", "read", "erase" 74 }; 75 #endif 76 77 struct _eeprom_t { 78 uint8_t tick; 79 uint8_t address; 80 uint8_t command; 81 uint8_t writable; 82 83 uint8_t eecs; 84 uint8_t eesk; 85 uint8_t eedo; 86 87 uint8_t addrbits; 88 uint16_t size; 89 uint16_t data; 90 uint16_t contents[0]; 91 }; 92 93 /* Code for saving and restoring of EEPROM state. */ 94 95 /* Restore an uint16_t from an uint8_t 96 This is a Big hack, but it is how the old state did it. 97 */ 98 99 static int get_uint16_from_uint8(QEMUFile *f, void *pv, size_t size, 100 const VMStateField *field) 101 { 102 uint16_t *v = pv; 103 *v = qemu_get_ubyte(f); 104 return 0; 105 } 106 107 static int put_unused(QEMUFile *f, void *pv, size_t size, 108 const VMStateField *field, QJSON *vmdesc) 109 { 110 fprintf(stderr, "uint16_from_uint8 is used only for backwards compatibility.\n"); 111 fprintf(stderr, "Never should be used to write a new state.\n"); 112 exit(0); 113 114 return 0; 115 } 116 117 static const VMStateInfo vmstate_hack_uint16_from_uint8 = { 118 .name = "uint16_from_uint8", 119 .get = get_uint16_from_uint8, 120 .put = put_unused, 121 }; 122 123 #define VMSTATE_UINT16_HACK_TEST(_f, _s, _t) \ 124 VMSTATE_SINGLE_TEST(_f, _s, _t, 0, vmstate_hack_uint16_from_uint8, uint16_t) 125 126 static bool is_old_eeprom_version(void *opaque, int version_id) 127 { 128 return version_id == OLD_EEPROM_VERSION; 129 } 130 131 static const VMStateDescription vmstate_eeprom = { 132 .name = "eeprom", 133 .version_id = EEPROM_VERSION, 134 .minimum_version_id = OLD_EEPROM_VERSION, 135 .fields = (VMStateField[]) { 136 VMSTATE_UINT8(tick, eeprom_t), 137 VMSTATE_UINT8(address, eeprom_t), 138 VMSTATE_UINT8(command, eeprom_t), 139 VMSTATE_UINT8(writable, eeprom_t), 140 141 VMSTATE_UINT8(eecs, eeprom_t), 142 VMSTATE_UINT8(eesk, eeprom_t), 143 VMSTATE_UINT8(eedo, eeprom_t), 144 145 VMSTATE_UINT8(addrbits, eeprom_t), 146 VMSTATE_UINT16_HACK_TEST(size, eeprom_t, is_old_eeprom_version), 147 VMSTATE_UNUSED_TEST(is_old_eeprom_version, 1), 148 VMSTATE_UINT16_EQUAL_V(size, eeprom_t, EEPROM_VERSION, NULL), 149 VMSTATE_UINT16(data, eeprom_t), 150 VMSTATE_VARRAY_UINT16_UNSAFE(contents, eeprom_t, size, 0, 151 vmstate_info_uint16, uint16_t), 152 VMSTATE_END_OF_LIST() 153 } 154 }; 155 156 void eeprom93xx_write(eeprom_t *eeprom, int eecs, int eesk, int eedi) 157 { 158 uint8_t tick = eeprom->tick; 159 uint8_t eedo = eeprom->eedo; 160 uint16_t address = eeprom->address; 161 uint8_t command = eeprom->command; 162 163 logout("CS=%u SK=%u DI=%u DO=%u, tick = %u\n", 164 eecs, eesk, eedi, eedo, tick); 165 166 if (!eeprom->eecs && eecs) { 167 /* Start chip select cycle. */ 168 logout("Cycle start, waiting for 1st start bit (0)\n"); 169 tick = 0; 170 command = 0x0; 171 address = 0x0; 172 } else if (eeprom->eecs && !eecs) { 173 /* End chip select cycle. This triggers write / erase. */ 174 if (eeprom->writable) { 175 uint8_t subcommand = address >> (eeprom->addrbits - 2); 176 if (command == 0 && subcommand == 2) { 177 /* Erase all. */ 178 for (address = 0; address < eeprom->size; address++) { 179 eeprom->contents[address] = 0xffff; 180 } 181 } else if (command == 3) { 182 /* Erase word. */ 183 eeprom->contents[address] = 0xffff; 184 } else if (tick >= 2 + 2 + eeprom->addrbits + 16) { 185 if (command == 1) { 186 /* Write word. */ 187 eeprom->contents[address] &= eeprom->data; 188 } else if (command == 0 && subcommand == 1) { 189 /* Write all. */ 190 for (address = 0; address < eeprom->size; address++) { 191 eeprom->contents[address] &= eeprom->data; 192 } 193 } 194 } 195 } 196 /* Output DO is tristate, read results in 1. */ 197 eedo = 1; 198 } else if (eecs && !eeprom->eesk && eesk) { 199 /* Raising edge of clock shifts data in. */ 200 if (tick == 0) { 201 /* Wait for 1st start bit. */ 202 if (eedi == 0) { 203 logout("Got correct 1st start bit, waiting for 2nd start bit (1)\n"); 204 tick++; 205 } else { 206 logout("wrong 1st start bit (is 1, should be 0)\n"); 207 tick = 2; 208 //~ assert(!"wrong start bit"); 209 } 210 } else if (tick == 1) { 211 /* Wait for 2nd start bit. */ 212 if (eedi != 0) { 213 logout("Got correct 2nd start bit, getting command + address\n"); 214 tick++; 215 } else { 216 logout("1st start bit is longer than needed\n"); 217 } 218 } else if (tick < 2 + 2) { 219 /* Got 2 start bits, transfer 2 opcode bits. */ 220 tick++; 221 command <<= 1; 222 if (eedi) { 223 command += 1; 224 } 225 } else if (tick < 2 + 2 + eeprom->addrbits) { 226 /* Got 2 start bits and 2 opcode bits, transfer all address bits. */ 227 tick++; 228 address = ((address << 1) | eedi); 229 if (tick == 2 + 2 + eeprom->addrbits) { 230 logout("%s command, address = 0x%02x (value 0x%04x)\n", 231 opstring[command], address, eeprom->contents[address]); 232 if (command == 2) { 233 eedo = 0; 234 } 235 address = address % eeprom->size; 236 if (command == 0) { 237 /* Command code in upper 2 bits of address. */ 238 switch (address >> (eeprom->addrbits - 2)) { 239 case 0: 240 logout("write disable command\n"); 241 eeprom->writable = 0; 242 break; 243 case 1: 244 logout("write all command\n"); 245 break; 246 case 2: 247 logout("erase all command\n"); 248 break; 249 case 3: 250 logout("write enable command\n"); 251 eeprom->writable = 1; 252 break; 253 } 254 } else { 255 /* Read, write or erase word. */ 256 eeprom->data = eeprom->contents[address]; 257 } 258 } 259 } else if (tick < 2 + 2 + eeprom->addrbits + 16) { 260 /* Transfer 16 data bits. */ 261 tick++; 262 if (command == 2) { 263 /* Read word. */ 264 eedo = ((eeprom->data & 0x8000) != 0); 265 } 266 eeprom->data <<= 1; 267 eeprom->data += eedi; 268 } else { 269 logout("additional unneeded tick, not processed\n"); 270 } 271 } 272 /* Save status of EEPROM. */ 273 eeprom->tick = tick; 274 eeprom->eecs = eecs; 275 eeprom->eesk = eesk; 276 eeprom->eedo = eedo; 277 eeprom->address = address; 278 eeprom->command = command; 279 } 280 281 uint16_t eeprom93xx_read(eeprom_t *eeprom) 282 { 283 /* Return status of pin DO (0 or 1). */ 284 logout("CS=%u DO=%u\n", eeprom->eecs, eeprom->eedo); 285 return eeprom->eedo; 286 } 287 288 #if 0 289 void eeprom93xx_reset(eeprom_t *eeprom) 290 { 291 /* prepare eeprom */ 292 logout("eeprom = 0x%p\n", eeprom); 293 eeprom->tick = 0; 294 eeprom->command = 0; 295 } 296 #endif 297 298 eeprom_t *eeprom93xx_new(DeviceState *dev, uint16_t nwords) 299 { 300 /* Add a new EEPROM (with 16, 64 or 256 words). */ 301 eeprom_t *eeprom; 302 uint8_t addrbits; 303 304 switch (nwords) { 305 case 16: 306 case 64: 307 addrbits = 6; 308 break; 309 case 128: 310 case 256: 311 addrbits = 8; 312 break; 313 default: 314 assert(!"Unsupported EEPROM size, fallback to 64 words!"); 315 nwords = 64; 316 addrbits = 6; 317 } 318 319 eeprom = (eeprom_t *)g_malloc0(sizeof(*eeprom) + nwords * 2); 320 eeprom->size = nwords; 321 eeprom->addrbits = addrbits; 322 /* Output DO is tristate, read results in 1. */ 323 eeprom->eedo = 1; 324 logout("eeprom = 0x%p, nwords = %u\n", eeprom, nwords); 325 vmstate_register(dev, 0, &vmstate_eeprom, eeprom); 326 return eeprom; 327 } 328 329 void eeprom93xx_free(DeviceState *dev, eeprom_t *eeprom) 330 { 331 /* Destroy EEPROM. */ 332 logout("eeprom = 0x%p\n", eeprom); 333 vmstate_unregister(dev, &vmstate_eeprom, eeprom); 334 g_free(eeprom); 335 } 336 337 uint16_t *eeprom93xx_data(eeprom_t *eeprom) 338 { 339 /* Get EEPROM data array. */ 340 return &eeprom->contents[0]; 341 } 342 343 /* eof */ 344