hw/nvram/eeprom_at24c.c

   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 <string.h>
  11
  12 #include "qemu/osdep.h"
  13 #include "qapi/error.h"
  14 #include "hw/hw.h"
  15 #include "hw/i2c/i2c.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
  32 typedef 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
  50 static
  51 int 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
  77 static
  78 int at24c_eeprom_recv(I2CSlave *s)
  79 {
  80     EEPROMState *ee = AT24C_EE(s);
  81     int 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
  91 static
  92 int 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
 120 static
 121 int at24c_eeprom_init(I2CSlave *i2c)
 122 {
 123     EEPROMState *ee = AT24C_EE(i2c);
 124
 125     ee->mem = g_malloc0(ee->rsize);
 126
 127     if (ee->blk) {
 128         int64_t len = blk_getlength(ee->blk);
 129
 130         if (len != ee->rsize) {
 131             ERR(TYPE_AT24C_EE " : Backing file size %lu != %u\n",
 132                     (unsigned long)len, (unsigned)ee->rsize);
 133             exit(1);
 134         }
 135
 136         if (blk_set_perm(ee->blk, BLK_PERM_CONSISTENT_READ | BLK_PERM_WRITE,
 137                          BLK_PERM_ALL, &error_fatal) < 0)
 138         {
 139             ERR(TYPE_AT24C_EE
 140                     " : Backing file incorrect permission\n");
 141             exit(1);
 142         }
 143     }
 144     return 0;
 145 }
 146
 147 static
 148 void at24c_eeprom_reset(DeviceState *state)
 149 {
 150     EEPROMState *ee = AT24C_EE(state);
 151
 152     ee->changed = false;
 153     ee->cur = 0;
 154     ee->haveaddr = 0;
 155
 156     memset(ee->mem, 0, ee->rsize);
 157
 158     if (ee->blk) {
 159         int len = blk_pread(ee->blk, 0, ee->mem, ee->rsize);
 160
 161         if (len != ee->rsize) {
 162             ERR(TYPE_AT24C_EE
 163                     " : Failed initial sync with backing file\n");
 164         }
 165         DPRINTK("Reset read backing file\n");
 166     }
 167 }
 168
 169 static Property at24c_eeprom_props[] = {
 170     DEFINE_PROP_UINT32("rom-size", EEPROMState, rsize, 0),
 171     DEFINE_PROP_BOOL("writable", EEPROMState, writable, true),
 172     DEFINE_PROP_DRIVE("drive", EEPROMState, blk),
 173     DEFINE_PROP_END_OF_LIST()
 174 };
 175
 176 static
 177 void at24c_eeprom_class_init(ObjectClass *klass, void *data)
 178 {
 179     DeviceClass *dc = DEVICE_CLASS(klass);
 180     I2CSlaveClass *k = I2C_SLAVE_CLASS(klass);
 181
 182     k->init = &at24c_eeprom_init;
 183     k->event = &at24c_eeprom_event;
 184     k->recv = &at24c_eeprom_recv;
 185     k->send = &at24c_eeprom_send;
 186
 187     dc->props = at24c_eeprom_props;
 188     dc->reset = at24c_eeprom_reset;
 189 }
 190
 191 static
 192 const TypeInfo at24c_eeprom_type = {
 193     .name = TYPE_AT24C_EE,
 194     .parent = TYPE_I2C_SLAVE,
 195     .instance_size = sizeof(EEPROMState),
 196     .class_size = sizeof(I2CSlaveClass),
 197     .class_init = at24c_eeprom_class_init,
 198 };
 199
 200 static void at24c_eeprom_register(void)
 201 {
 202     type_register_static(&at24c_eeprom_type);
 203 }
 204
 205 type_init(at24c_eeprom_register)