xref: /openbmc/qemu/hw/nvram/eeprom_at24c.c (revision d3860a57) 
1 /*
2  * *AT24C* series I2C EEPROM
3  *
4  * Copyright (c) 2015 Michael Davidsaver
5  *
6  * This work is licensed under the terms of the GNU GPL, version 2.  See
7  * the LICENSE file in the top-level directory.
8  */
9 
10 #include "qemu/osdep.h"
11 
12 #include "qapi/error.h"
13 #include "qemu/module.h"
14 #include "hw/i2c/i2c.h"
15 #include "hw/nvram/eeprom_at24c.h"
16 #include "hw/qdev-properties.h"
17 #include "hw/qdev-properties-system.h"
18 #include "sysemu/block-backend.h"
19 #include "qom/object.h"
20 
21 /* #define DEBUG_AT24C */
22 
23 #ifdef DEBUG_AT24C
24 #define DPRINTK(FMT, ...) printf(TYPE_AT24C_EE " : " FMT, ## __VA_ARGS__)
25 #else
26 #define DPRINTK(FMT, ...) do {} while (0)
27 #endif
28 
29 #define ERR(FMT, ...) fprintf(stderr, TYPE_AT24C_EE " : " FMT, \
30                             ## __VA_ARGS__)
31 
32 #define TYPE_AT24C_EE "at24c-eeprom"
33 typedef struct EEPROMState EEPROMState;
34 DECLARE_INSTANCE_CHECKER(EEPROMState, AT24C_EE,
35                          TYPE_AT24C_EE)
36 
37 struct EEPROMState {
38     I2CSlave parent_obj;
39 
40     /* address counter */
41     uint16_t cur;
42     /* total size in bytes */
43     uint32_t rsize;
44     /*
45      * address byte number
46      *  for  24c01, 24c02 size <= 256 byte, use only 1 byte
47      *  otherwise size > 256, use 2 byte
48      */
49     uint8_t asize;
50 
51     bool writable;
52     /* cells changed since last START? */
53     bool changed;
54     /* during WRITE, # of address bytes transfered */
55     uint8_t haveaddr;
56 
57     uint8_t *mem;
58 
59     BlockBackend *blk;
60 
61     const uint8_t *init_rom;
62     uint32_t init_rom_size;
63 };
64 
65 static
66 int at24c_eeprom_event(I2CSlave *s, enum i2c_event event)
67 {
68     EEPROMState *ee = AT24C_EE(s);
69 
70     switch (event) {
71     case I2C_START_SEND:
72     case I2C_FINISH:
73         ee->haveaddr = 0;
74         /* fallthrough */
75     case I2C_START_RECV:
76         DPRINTK("clear\n");
77         if (ee->blk && ee->changed) {
78             int ret = blk_pwrite(ee->blk, 0, ee->rsize, ee->mem, 0);
79             if (ret < 0) {
80                 ERR(TYPE_AT24C_EE
81                         " : failed to write backing file\n");
82             }
83             DPRINTK("Wrote to backing file\n");
84         }
85         ee->changed = false;
86         break;
87     case I2C_NACK:
88         break;
89     default:
90         return -1;
91     }
92     return 0;
93 }
94 
95 static
96 uint8_t at24c_eeprom_recv(I2CSlave *s)
97 {
98     EEPROMState *ee = AT24C_EE(s);
99     uint8_t ret;
100 
101     /*
102      * If got the byte address but not completely with address size
103      * will return the invalid value
104      */
105     if (ee->haveaddr > 0 && ee->haveaddr < ee->asize) {
106         return 0xff;
107     }
108 
109     ret = ee->mem[ee->cur];
110 
111     ee->cur = (ee->cur + 1u) % ee->rsize;
112     DPRINTK("Recv %02x %c\n", ret, ret);
113 
114     return ret;
115 }
116 
117 static
118 int at24c_eeprom_send(I2CSlave *s, uint8_t data)
119 {
120     EEPROMState *ee = AT24C_EE(s);
121 
122     if (ee->haveaddr < ee->asize) {
123         ee->cur <<= 8;
124         ee->cur |= data;
125         ee->haveaddr++;
126         if (ee->haveaddr == ee->asize) {
127             ee->cur %= ee->rsize;
128             DPRINTK("Set pointer %04x\n", ee->cur);
129         }
130 
131     } else {
132         if (ee->writable) {
133             DPRINTK("Send %02x\n", data);
134             ee->mem[ee->cur] = data;
135             ee->changed = true;
136         } else {
137             DPRINTK("Send error %02x read-only\n", data);
138         }
139         ee->cur = (ee->cur + 1u) % ee->rsize;
140 
141     }
142 
143     return 0;
144 }
145 
146 I2CSlave *at24c_eeprom_init(I2CBus *bus, uint8_t address, uint32_t rom_size)
147 {
148     return at24c_eeprom_init_rom(bus, address, rom_size, NULL, 0);
149 }
150 
151 I2CSlave *at24c_eeprom_init_rom(I2CBus *bus, uint8_t address, uint32_t rom_size,
152                                 const uint8_t *init_rom, uint32_t init_rom_size)
153 {
154     EEPROMState *s;
155 
156     s = AT24C_EE(i2c_slave_new(TYPE_AT24C_EE, address));
157 
158     qdev_prop_set_uint32(DEVICE(s), "rom-size", rom_size);
159 
160     /* TODO: Model init_rom with QOM properties. */
161     s->init_rom = init_rom;
162     s->init_rom_size = init_rom_size;
163 
164     i2c_slave_realize_and_unref(I2C_SLAVE(s), bus, &error_abort);
165 
166     return I2C_SLAVE(s);
167 }
168 
169 static void at24c_eeprom_realize(DeviceState *dev, Error **errp)
170 {
171     EEPROMState *ee = AT24C_EE(dev);
172 
173     if (ee->init_rom_size > ee->rsize) {
174         error_setg(errp, "%s: init rom is larger than rom: %u > %u",
175                    TYPE_AT24C_EE, ee->init_rom_size, ee->rsize);
176         return;
177     }
178 
179     if (ee->blk) {
180         int64_t len = blk_getlength(ee->blk);
181 
182         if (len != ee->rsize) {
183             error_setg(errp, "%s: Backing file size %" PRId64 " != %u",
184                        TYPE_AT24C_EE, len, ee->rsize);
185             return;
186         }
187 
188         if (blk_set_perm(ee->blk, BLK_PERM_CONSISTENT_READ | BLK_PERM_WRITE,
189                          BLK_PERM_ALL, &error_fatal) < 0)
190         {
191             error_setg(errp, "%s: Backing file incorrect permission",
192                        TYPE_AT24C_EE);
193             return;
194         }
195     }
196 
197     ee->mem = g_malloc0(ee->rsize);
198     memset(ee->mem, 0, ee->rsize);
199 
200     if (ee->init_rom) {
201         memcpy(ee->mem, ee->init_rom, MIN(ee->init_rom_size, ee->rsize));
202     }
203 
204     if (ee->blk) {
205         int ret = blk_pread(ee->blk, 0, ee->rsize, ee->mem, 0);
206 
207         if (ret < 0) {
208             ERR(TYPE_AT24C_EE
209                     " : Failed initial sync with backing file\n");
210         }
211         DPRINTK("Reset read backing file\n");
212     }
213 
214     /*
215      * If address size didn't define with property set
216      *   value is 0 as default, setting it by Rom size detecting.
217      */
218     if (ee->asize == 0) {
219         if (ee->rsize <= 256) {
220             ee->asize = 1;
221         } else {
222             ee->asize = 2;
223         }
224     }
225 }
226 
227 static
228 void at24c_eeprom_reset(DeviceState *state)
229 {
230     EEPROMState *ee = AT24C_EE(state);
231 
232     ee->changed = false;
233     ee->cur = 0;
234     ee->haveaddr = 0;
235 }
236 
237 static Property at24c_eeprom_props[] = {
238     DEFINE_PROP_UINT32("rom-size", EEPROMState, rsize, 0),
239     DEFINE_PROP_UINT8("address-size", EEPROMState, asize, 0),
240     DEFINE_PROP_BOOL("writable", EEPROMState, writable, true),
241     DEFINE_PROP_DRIVE("drive", EEPROMState, blk),
242     DEFINE_PROP_END_OF_LIST()
243 };
244 
245 static
246 void at24c_eeprom_class_init(ObjectClass *klass, void *data)
247 {
248     DeviceClass *dc = DEVICE_CLASS(klass);
249     I2CSlaveClass *k = I2C_SLAVE_CLASS(klass);
250 
251     dc->realize = &at24c_eeprom_realize;
252     k->event = &at24c_eeprom_event;
253     k->recv = &at24c_eeprom_recv;
254     k->send = &at24c_eeprom_send;
255 
256     device_class_set_props(dc, at24c_eeprom_props);
257     dc->reset = at24c_eeprom_reset;
258 }
259 
260 static
261 const TypeInfo at24c_eeprom_type = {
262     .name = TYPE_AT24C_EE,
263     .parent = TYPE_I2C_SLAVE,
264     .instance_size = sizeof(EEPROMState),
265     .class_size = sizeof(I2CSlaveClass),
266     .class_init = at24c_eeprom_class_init,
267 };
268 
269 static void at24c_eeprom_register(void)
270 {
271     type_register_static(&at24c_eeprom_type);
272 }
273 
274 type_init(at24c_eeprom_register)
275