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 |
57 | typedef 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 |
71 | static const char *opstring[] = { |
72 | "extended" , "write" , "read" , "erase" |
73 | }; |
74 | #endif |
75 | |
76 | struct _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[0]; |
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 | |
98 | static 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 | |
106 | static int put_unused(QEMUFile *f, void *pv, size_t size, |
107 | const VMStateField *field, QJSON *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 | |
116 | static 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 | |
125 | static bool is_old_eeprom_version(void *opaque, int version_id) |
126 | { |
127 | return version_id == OLD_EEPROM_VERSION; |
128 | } |
129 | |
130 | static 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 | |
155 | void 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 | |
280 | uint16_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 |
288 | void 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 | |
297 | eeprom_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(dev, 0, &vmstate_eeprom, eeprom); |
325 | return eeprom; |
326 | } |
327 | |
328 | void eeprom93xx_free(DeviceState *dev, eeprom_t *eeprom) |
329 | { |
330 | /* Destroy EEPROM. */ |
331 | logout("eeprom = 0x%p\n" , eeprom); |
332 | vmstate_unregister(dev, &vmstate_eeprom, eeprom); |
333 | g_free(eeprom); |
334 | } |
335 | |
336 | uint16_t *eeprom93xx_data(eeprom_t *eeprom) |
337 | { |
338 | /* Get EEPROM data array. */ |
339 | return &eeprom->contents[0]; |
340 | } |
341 | |
342 | /* eof */ |
343 | |