xref: /illumos-kvm-cmd/hw/eeprom93xx.c (revision 68396ea9)
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.h"
39 #include "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  writeable;
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 
get_uint16_from_uint8(QEMUFile * f,void * pv,size_t size)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 
put_unused(QEMUFile * f,void * pv,size_t size)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 
is_old_eeprom_version(void * opaque,int version_id)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(writeable, 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 
eeprom93xx_write(eeprom_t * eeprom,int eecs,int eesk,int eedi)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->writeable) {
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->writeable = 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->writeable = 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 
eeprom93xx_read(eeprom_t * eeprom)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 
eeprom93xx_new(DeviceState * dev,uint16_t nwords)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 *)qemu_mallocz(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 
eeprom93xx_free(DeviceState * dev,eeprom_t * eeprom)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     qemu_free(eeprom);
329 }
330 
eeprom93xx_data(eeprom_t * eeprom)331 uint16_t *eeprom93xx_data(eeprom_t *eeprom)
332 {
333     /* Get EEPROM data array. */
334     return &eeprom->contents[0];
335 }
336 
337 /* eof */
338