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/qdev-properties.h"
16#include "sysemu/block-backend.h"
17
18/* #define DEBUG_AT24C */
19
20#ifdef DEBUG_AT24C
21#define DPRINTK(FMT, ...) printf(TYPE_AT24C_EE " : " FMT, ## __VA_ARGS__)
22#else
23#define DPRINTK(FMT, ...) do {} while (0)
24#endif
25
26#define ERR(FMT, ...) fprintf(stderr, TYPE_AT24C_EE " : " FMT, \
27 ## __VA_ARGS__)
28
29#define TYPE_AT24C_EE "at24c-eeprom"
30#define AT24C_EE(obj) OBJECT_CHECK(EEPROMState, (obj), TYPE_AT24C_EE)
31
32typedef struct EEPROMState {
33 I2CSlave parent_obj;
34
35 /* address counter */
36 uint16_t cur;
37 /* total size in bytes */
38 uint32_t rsize;
39 bool writable;
40 /* cells changed since last START? */
41 bool changed;
42 /* during WRITE, # of address bytes transfered */
43 uint8_t haveaddr;
44
45 uint8_t *mem;
46
47 BlockBackend *blk;
48} EEPROMState;
49
50static
51int at24c_eeprom_event(I2CSlave *s, enum i2c_event event)
52{
53 EEPROMState *ee = container_of(s, EEPROMState, parent_obj);
54
55 switch (event) {
56 case I2C_START_SEND:
57 case I2C_START_RECV:
58 case I2C_FINISH:
59 ee->haveaddr = 0;
60 DPRINTK("clear\n");
61 if (ee->blk && ee->changed) {
62 int len = blk_pwrite(ee->blk, 0, ee->mem, ee->rsize, 0);
63 if (len != ee->rsize) {
64 ERR(TYPE_AT24C_EE
65 " : failed to write backing file\n");
66 }
67 DPRINTK("Wrote to backing file\n");
68 }
69 ee->changed = false;
70 break;
71 case I2C_NACK:
72 break;
73 }
74 return 0;
75}
76
77static
78uint8_t at24c_eeprom_recv(I2CSlave *s)
79{
80 EEPROMState *ee = AT24C_EE(s);
81 uint8_t ret;
82
83 ret = ee->mem[ee->cur];
84
85 ee->cur = (ee->cur + 1u) % ee->rsize;
86 DPRINTK("Recv %02x %c\n", ret, ret);
87
88 return ret;
89}
90
91static
92int at24c_eeprom_send(I2CSlave *s, uint8_t data)
93{
94 EEPROMState *ee = AT24C_EE(s);
95
96 if (ee->haveaddr < 2) {
97 ee->cur <<= 8;
98 ee->cur |= data;
99 ee->haveaddr++;
100 if (ee->haveaddr == 2) {
101 ee->cur %= ee->rsize;
102 DPRINTK("Set pointer %04x\n", ee->cur);
103 }
104
105 } else {
106 if (ee->writable) {
107 DPRINTK("Send %02x\n", data);
108 ee->mem[ee->cur] = data;
109 ee->changed = true;
110 } else {
111 DPRINTK("Send error %02x read-only\n", data);
112 }
113 ee->cur = (ee->cur + 1u) % ee->rsize;
114
115 }
116
117 return 0;
118}
119
120static void at24c_eeprom_realize(DeviceState *dev, Error **errp)
121{
122 EEPROMState *ee = AT24C_EE(dev);
123
124 if (ee->blk) {
125 int64_t len = blk_getlength(ee->blk);
126
127 if (len != ee->rsize) {
128 error_setg(errp, "%s: Backing file size %" PRId64 " != %u",
129 TYPE_AT24C_EE, len, ee->rsize);
130 return;
131 }
132
133 if (blk_set_perm(ee->blk, BLK_PERM_CONSISTENT_READ | BLK_PERM_WRITE,
134 BLK_PERM_ALL, &error_fatal) < 0)
135 {
136 error_setg(errp, "%s: Backing file incorrect permission",
137 TYPE_AT24C_EE);
138 return;
139 }
140 }
141
142 ee->mem = g_malloc0(ee->rsize);
143}
144
145static
146void at24c_eeprom_reset(DeviceState *state)
147{
148 EEPROMState *ee = AT24C_EE(state);
149
150 ee->changed = false;
151 ee->cur = 0;
152 ee->haveaddr = 0;
153
154 memset(ee->mem, 0, ee->rsize);
155
156 if (ee->blk) {
157 int len = blk_pread(ee->blk, 0, ee->mem, ee->rsize);
158
159 if (len != ee->rsize) {
160 ERR(TYPE_AT24C_EE
161 " : Failed initial sync with backing file\n");
162 }
163 DPRINTK("Reset read backing file\n");
164 }
165}
166
167static Property at24c_eeprom_props[] = {
168 DEFINE_PROP_UINT32("rom-size", EEPROMState, rsize, 0),
169 DEFINE_PROP_BOOL("writable", EEPROMState, writable, true),
170 DEFINE_PROP_DRIVE("drive", EEPROMState, blk),
171 DEFINE_PROP_END_OF_LIST()
172};
173
174static
175void at24c_eeprom_class_init(ObjectClass *klass, void *data)
176{
177 DeviceClass *dc = DEVICE_CLASS(klass);
178 I2CSlaveClass *k = I2C_SLAVE_CLASS(klass);
179
180 dc->realize = &at24c_eeprom_realize;
181 k->event = &at24c_eeprom_event;
182 k->recv = &at24c_eeprom_recv;
183 k->send = &at24c_eeprom_send;
184
185 dc->props = at24c_eeprom_props;
186 dc->reset = at24c_eeprom_reset;
187}
188
189static
190const TypeInfo at24c_eeprom_type = {
191 .name = TYPE_AT24C_EE,
192 .parent = TYPE_I2C_SLAVE,
193 .instance_size = sizeof(EEPROMState),
194 .class_size = sizeof(I2CSlaveClass),
195 .class_init = at24c_eeprom_class_init,
196};
197
198static void at24c_eeprom_register(void)
199{
200 type_register_static(&at24c_eeprom_type);
201}
202
203type_init(at24c_eeprom_register)
204