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 "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 #include "qom/object.h"
  18
  19 /* #define DEBUG_AT24C */
  20
  21 #ifdef DEBUG_AT24C
  22 #define DPRINTK(FMT, ...) printf(TYPE_AT24C_EE " : " FMT, ## __VA_ARGS__)
  23 #else
  24 #define DPRINTK(FMT, ...) do {} while (0)
  25 #endif
  26
  27 #define ERR(FMT, ...) fprintf(stderr, TYPE_AT24C_EE " : " FMT, \
  28                             ## __VA_ARGS__)
  29
  30 #define TYPE_AT24C_EE "at24c-eeprom"
  31 typedef struct EEPROMState EEPROMState;
  32 DECLARE_INSTANCE_CHECKER(EEPROMState, AT24C_EE,
  33                          TYPE_AT24C_EE)
  34
  35 struct EEPROMState {
  36     I2CSlave parent_obj;
  37
  38     /* address counter */
  39     uint16_t cur;
  40     /* total size in bytes */
  41     uint32_t rsize;
  42     bool writable;
  43     /* cells changed since last START? */
  44     bool changed;
  45     /* during WRITE, # of address bytes transfered */
  46     uint8_t haveaddr;
  47
  48     uint8_t *mem;
  49
  50     BlockBackend *blk;
  51 };
  52
  53 static
  54 int at24c_eeprom_event(I2CSlave *s, enum i2c_event event)
  55 {
  56     EEPROMState *ee = container_of(s, EEPROMState, parent_obj);
  57
  58     switch (event) {
  59     case I2C_START_SEND:
  60     case I2C_START_RECV:
  61     case I2C_FINISH:
  62         ee->haveaddr = 0;
  63         DPRINTK("clear\n");
  64         if (ee->blk && ee->changed) {
  65             int len = blk_pwrite(ee->blk, 0, ee->mem, ee->rsize, 0);
  66             if (len != ee->rsize) {
  67                 ERR(TYPE_AT24C_EE
  68                         " : failed to write backing file\n");
  69             }
  70             DPRINTK("Wrote to backing file\n");
  71         }
  72         ee->changed = false;
  73         break;
  74     case I2C_NACK:
  75         break;
  76     }
  77     return 0;
  78 }
  79
  80 static
  81 uint8_t at24c_eeprom_recv(I2CSlave *s)
  82 {
  83     EEPROMState *ee = AT24C_EE(s);
  84     uint8_t ret;
  85
  86     ret = ee->mem[ee->cur];
  87
  88     ee->cur = (ee->cur + 1u) % ee->rsize;
  89     DPRINTK("Recv %02x %c\n", ret, ret);
  90
  91     return ret;
  92 }
  93
  94 static
  95 int at24c_eeprom_send(I2CSlave *s, uint8_t data)
  96 {
  97     EEPROMState *ee = AT24C_EE(s);
  98
  99     if (ee->haveaddr < 2) {
 100         ee->cur <<= 8;
 101         ee->cur |= data;
 102         ee->haveaddr++;
 103         if (ee->haveaddr == 2) {
 104             ee->cur %= ee->rsize;
 105             DPRINTK("Set pointer %04x\n", ee->cur);
 106         }
 107
 108     } else {
 109         if (ee->writable) {
 110             DPRINTK("Send %02x\n", data);
 111             ee->mem[ee->cur] = data;
 112             ee->changed = true;
 113         } else {
 114             DPRINTK("Send error %02x read-only\n", data);
 115         }
 116         ee->cur = (ee->cur + 1u) % ee->rsize;
 117
 118     }
 119
 120     return 0;
 121 }
 122
 123 static void at24c_eeprom_realize(DeviceState *dev, Error **errp)
 124 {
 125     EEPROMState *ee = AT24C_EE(dev);
 126
 127     if (ee->blk) {
 128         int64_t len = blk_getlength(ee->blk);
 129
 130         if (len != ee->rsize) {
 131             error_setg(errp, "%s: Backing file size %" PRId64 " != %u",
 132                        TYPE_AT24C_EE, len, ee->rsize);
 133             return;
 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             error_setg(errp, "%s: Backing file incorrect permission",
 140                        TYPE_AT24C_EE);
 141             return;
 142         }
 143     }
 144
 145     ee->mem = g_malloc0(ee->rsize);
 146 }
 147
 148 static
 149 void at24c_eeprom_reset(DeviceState *state)
 150 {
 151     EEPROMState *ee = AT24C_EE(state);
 152
 153     ee->changed = false;
 154     ee->cur = 0;
 155     ee->haveaddr = 0;
 156
 157     memset(ee->mem, 0, ee->rsize);
 158
 159     if (ee->blk) {
 160         int len = blk_pread(ee->blk, 0, ee->mem, ee->rsize);
 161
 162         if (len != ee->rsize) {
 163             ERR(TYPE_AT24C_EE
 164                     " : Failed initial sync with backing file\n");
 165         }
 166         DPRINTK("Reset read backing file\n");
 167     }
 168 }
 169
 170 static Property at24c_eeprom_props[] = {
 171     DEFINE_PROP_UINT32("rom-size", EEPROMState, rsize, 0),
 172     DEFINE_PROP_BOOL("writable", EEPROMState, writable, true),
 173     DEFINE_PROP_DRIVE("drive", EEPROMState, blk),
 174     DEFINE_PROP_END_OF_LIST()
 175 };
 176
 177 static
 178 void at24c_eeprom_class_init(ObjectClass *klass, void *data)
 179 {
 180     DeviceClass *dc = DEVICE_CLASS(klass);
 181     I2CSlaveClass *k = I2C_SLAVE_CLASS(klass);
 182
 183     dc->realize = &at24c_eeprom_realize;
 184     k->event = &at24c_eeprom_event;
 185     k->recv = &at24c_eeprom_recv;
 186     k->send = &at24c_eeprom_send;
 187
 188     device_class_set_props(dc, at24c_eeprom_props);
 189     dc->reset = at24c_eeprom_reset;
 190 }
 191
 192 static
 193 const TypeInfo at24c_eeprom_type = {
 194     .name = TYPE_AT24C_EE,
 195     .parent = TYPE_I2C_SLAVE,
 196     .instance_size = sizeof(EEPROMState),
 197     .class_size = sizeof(I2CSlaveClass),
 198     .class_init = at24c_eeprom_class_init,
 199 };
 200
 201 static void at24c_eeprom_register(void)
 202 {
 203     type_register_static(&at24c_eeprom_type);
 204 }
 205
 206 type_init(at24c_eeprom_register)