eeprom93xx.c (10794B)
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/nvram/eeprom93xx.h" 40#include "migration/qemu-file-types.h" 41#include "migration/vmstate.h" 42 43/* Debug EEPROM emulation. */ 44//~ #define DEBUG_EEPROM 45 46#ifdef DEBUG_EEPROM 47#define logout(fmt, ...) fprintf(stderr, "EEPROM\t%-24s" fmt, __func__, ## __VA_ARGS__) 48#else 49#define logout(fmt, ...) ((void)0) 50#endif 51 52#define EEPROM_INSTANCE 0 53#define OLD_EEPROM_VERSION 20061112 54#define EEPROM_VERSION (OLD_EEPROM_VERSION + 1) 55 56#if 0 57typedef enum { 58 eeprom_read = 0x80, /* read register xx */ 59 eeprom_write = 0x40, /* write register xx */ 60 eeprom_erase = 0xc0, /* erase register xx */ 61 eeprom_ewen = 0x30, /* erase / write enable */ 62 eeprom_ewds = 0x00, /* erase / write disable */ 63 eeprom_eral = 0x20, /* erase all registers */ 64 eeprom_wral = 0x10, /* write all registers */ 65 eeprom_amask = 0x0f, 66 eeprom_imask = 0xf0 67} eeprom_instruction_t; 68#endif 69 70#ifdef DEBUG_EEPROM 71static const char *opstring[] = { 72 "extended", "write", "read", "erase" 73}; 74#endif 75 76struct _eeprom_t { 77 uint8_t tick; 78 uint8_t address; 79 uint8_t command; 80 uint8_t writable; 81 82 uint8_t eecs; 83 uint8_t eesk; 84 uint8_t eedo; 85 86 uint8_t addrbits; 87 uint16_t size; 88 uint16_t data; 89 uint16_t contents[]; 90}; 91 92/* Code for saving and restoring of EEPROM state. */ 93 94/* Restore an uint16_t from an uint8_t 95 This is a Big hack, but it is how the old state did it. 96 */ 97 98static int get_uint16_from_uint8(QEMUFile *f, void *pv, size_t size, 99 const VMStateField *field) 100{ 101 uint16_t *v = pv; 102 *v = qemu_get_ubyte(f); 103 return 0; 104} 105 106static int put_unused(QEMUFile *f, void *pv, size_t size, 107 const VMStateField *field, JSONWriter *vmdesc) 108{ 109 fprintf(stderr, "uint16_from_uint8 is used only for backwards compatibility.\n"); 110 fprintf(stderr, "Never should be used to write a new state.\n"); 111 exit(0); 112 113 return 0; 114} 115 116static const VMStateInfo vmstate_hack_uint16_from_uint8 = { 117 .name = "uint16_from_uint8", 118 .get = get_uint16_from_uint8, 119 .put = put_unused, 120}; 121 122#define VMSTATE_UINT16_HACK_TEST(_f, _s, _t) \ 123 VMSTATE_SINGLE_TEST(_f, _s, _t, 0, vmstate_hack_uint16_from_uint8, uint16_t) 124 125static bool is_old_eeprom_version(void *opaque, int version_id) 126{ 127 return version_id == OLD_EEPROM_VERSION; 128} 129 130static const VMStateDescription vmstate_eeprom = { 131 .name = "eeprom", 132 .version_id = EEPROM_VERSION, 133 .minimum_version_id = OLD_EEPROM_VERSION, 134 .fields = (VMStateField[]) { 135 VMSTATE_UINT8(tick, eeprom_t), 136 VMSTATE_UINT8(address, eeprom_t), 137 VMSTATE_UINT8(command, eeprom_t), 138 VMSTATE_UINT8(writable, eeprom_t), 139 140 VMSTATE_UINT8(eecs, eeprom_t), 141 VMSTATE_UINT8(eesk, eeprom_t), 142 VMSTATE_UINT8(eedo, eeprom_t), 143 144 VMSTATE_UINT8(addrbits, eeprom_t), 145 VMSTATE_UINT16_HACK_TEST(size, eeprom_t, is_old_eeprom_version), 146 VMSTATE_UNUSED_TEST(is_old_eeprom_version, 1), 147 VMSTATE_UINT16_EQUAL_V(size, eeprom_t, EEPROM_VERSION, NULL), 148 VMSTATE_UINT16(data, eeprom_t), 149 VMSTATE_VARRAY_UINT16_UNSAFE(contents, eeprom_t, size, 0, 150 vmstate_info_uint16, uint16_t), 151 VMSTATE_END_OF_LIST() 152 } 153}; 154 155void eeprom93xx_write(eeprom_t *eeprom, int eecs, int eesk, int eedi) 156{ 157 uint8_t tick = eeprom->tick; 158 uint8_t eedo = eeprom->eedo; 159 uint16_t address = eeprom->address; 160 uint8_t command = eeprom->command; 161 162 logout("CS=%u SK=%u DI=%u DO=%u, tick = %u\n", 163 eecs, eesk, eedi, eedo, tick); 164 165 if (!eeprom->eecs && eecs) { 166 /* Start chip select cycle. */ 167 logout("Cycle start, waiting for 1st start bit (0)\n"); 168 tick = 0; 169 command = 0x0; 170 address = 0x0; 171 } else if (eeprom->eecs && !eecs) { 172 /* End chip select cycle. This triggers write / erase. */ 173 if (eeprom->writable) { 174 uint8_t subcommand = address >> (eeprom->addrbits - 2); 175 if (command == 0 && subcommand == 2) { 176 /* Erase all. */ 177 for (address = 0; address < eeprom->size; address++) { 178 eeprom->contents[address] = 0xffff; 179 } 180 } else if (command == 3) { 181 /* Erase word. */ 182 eeprom->contents[address] = 0xffff; 183 } else if (tick >= 2 + 2 + eeprom->addrbits + 16) { 184 if (command == 1) { 185 /* Write word. */ 186 eeprom->contents[address] &= eeprom->data; 187 } else if (command == 0 && subcommand == 1) { 188 /* Write all. */ 189 for (address = 0; address < eeprom->size; address++) { 190 eeprom->contents[address] &= eeprom->data; 191 } 192 } 193 } 194 } 195 /* Output DO is tristate, read results in 1. */ 196 eedo = 1; 197 } else if (eecs && !eeprom->eesk && eesk) { 198 /* Raising edge of clock shifts data in. */ 199 if (tick == 0) { 200 /* Wait for 1st start bit. */ 201 if (eedi == 0) { 202 logout("Got correct 1st start bit, waiting for 2nd start bit (1)\n"); 203 tick++; 204 } else { 205 logout("wrong 1st start bit (is 1, should be 0)\n"); 206 tick = 2; 207 //~ assert(!"wrong start bit"); 208 } 209 } else if (tick == 1) { 210 /* Wait for 2nd start bit. */ 211 if (eedi != 0) { 212 logout("Got correct 2nd start bit, getting command + address\n"); 213 tick++; 214 } else { 215 logout("1st start bit is longer than needed\n"); 216 } 217 } else if (tick < 2 + 2) { 218 /* Got 2 start bits, transfer 2 opcode bits. */ 219 tick++; 220 command <<= 1; 221 if (eedi) { 222 command += 1; 223 } 224 } else if (tick < 2 + 2 + eeprom->addrbits) { 225 /* Got 2 start bits and 2 opcode bits, transfer all address bits. */ 226 tick++; 227 address = ((address << 1) | eedi); 228 if (tick == 2 + 2 + eeprom->addrbits) { 229 logout("%s command, address = 0x%02x (value 0x%04x)\n", 230 opstring[command], address, eeprom->contents[address]); 231 if (command == 2) { 232 eedo = 0; 233 } 234 address = address % eeprom->size; 235 if (command == 0) { 236 /* Command code in upper 2 bits of address. */ 237 switch (address >> (eeprom->addrbits - 2)) { 238 case 0: 239 logout("write disable command\n"); 240 eeprom->writable = 0; 241 break; 242 case 1: 243 logout("write all command\n"); 244 break; 245 case 2: 246 logout("erase all command\n"); 247 break; 248 case 3: 249 logout("write enable command\n"); 250 eeprom->writable = 1; 251 break; 252 } 253 } else { 254 /* Read, write or erase word. */ 255 eeprom->data = eeprom->contents[address]; 256 } 257 } 258 } else if (tick < 2 + 2 + eeprom->addrbits + 16) { 259 /* Transfer 16 data bits. */ 260 tick++; 261 if (command == 2) { 262 /* Read word. */ 263 eedo = ((eeprom->data & 0x8000) != 0); 264 } 265 eeprom->data <<= 1; 266 eeprom->data += eedi; 267 } else { 268 logout("additional unneeded tick, not processed\n"); 269 } 270 } 271 /* Save status of EEPROM. */ 272 eeprom->tick = tick; 273 eeprom->eecs = eecs; 274 eeprom->eesk = eesk; 275 eeprom->eedo = eedo; 276 eeprom->address = address; 277 eeprom->command = command; 278} 279 280uint16_t eeprom93xx_read(eeprom_t *eeprom) 281{ 282 /* Return status of pin DO (0 or 1). */ 283 logout("CS=%u DO=%u\n", eeprom->eecs, eeprom->eedo); 284 return eeprom->eedo; 285} 286 287#if 0 288void eeprom93xx_reset(eeprom_t *eeprom) 289{ 290 /* prepare eeprom */ 291 logout("eeprom = 0x%p\n", eeprom); 292 eeprom->tick = 0; 293 eeprom->command = 0; 294} 295#endif 296 297eeprom_t *eeprom93xx_new(DeviceState *dev, uint16_t nwords) 298{ 299 /* Add a new EEPROM (with 16, 64 or 256 words). */ 300 eeprom_t *eeprom; 301 uint8_t addrbits; 302 303 switch (nwords) { 304 case 16: 305 case 64: 306 addrbits = 6; 307 break; 308 case 128: 309 case 256: 310 addrbits = 8; 311 break; 312 default: 313 assert(!"Unsupported EEPROM size, fallback to 64 words!"); 314 nwords = 64; 315 addrbits = 6; 316 } 317 318 eeprom = (eeprom_t *)g_malloc0(sizeof(*eeprom) + nwords * 2); 319 eeprom->size = nwords; 320 eeprom->addrbits = addrbits; 321 /* Output DO is tristate, read results in 1. */ 322 eeprom->eedo = 1; 323 logout("eeprom = 0x%p, nwords = %u\n", eeprom, nwords); 324 vmstate_register(VMSTATE_IF(dev), 0, &vmstate_eeprom, eeprom); 325 return eeprom; 326} 327 328void eeprom93xx_free(DeviceState *dev, eeprom_t *eeprom) 329{ 330 /* Destroy EEPROM. */ 331 logout("eeprom = 0x%p\n", eeprom); 332 vmstate_unregister(VMSTATE_IF(dev), &vmstate_eeprom, eeprom); 333 g_free(eeprom); 334} 335 336uint16_t *eeprom93xx_data(eeprom_t *eeprom) 337{ 338 /* Get EEPROM data array. */ 339 return &eeprom->contents[0]; 340} 341 342/* eof */