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 "hw/qdev-properties-system.h"
  17 #include "sysemu/block-backend.h"
  18 #include "qom/object.h"
  19
  20 /* #define DEBUG_AT24C */
  21
  22 #ifdef DEBUG_AT24C
  23 #define DPRINTK(FMT, ...) printf(TYPE_AT24C_EE " : " FMT, ## __VA_ARGS__)
  24 #else
  25 #define DPRINTK(FMT, ...) do {} while (0)
  26 #endif
  27
  28 #define ERR(FMT, ...) fprintf(stderr, TYPE_AT24C_EE " : " FMT, \
  29                             ## __VA_ARGS__)
  30
  31 #define TYPE_AT24C_EE "at24c-eeprom"
  32 typedef struct EEPROMState EEPROMState;
  33 DECLARE_INSTANCE_CHECKER(EEPROMState, AT24C_EE,
  34                          TYPE_AT24C_EE)
  35
  36 struct EEPROMState {
  37     I2CSlave parent_obj;
  38
  39     /* address counter */
  40     uint16_t cur;
  41     /* total size in bytes */
  42     uint32_t rsize;
  43     bool writable;
  44     /* cells changed since last START? */
  45     bool changed;
  46     /* during WRITE, # of address bytes transfered */
  47     uint8_t haveaddr;
  48
  49     uint8_t *mem;
  50
  51     BlockBackend *blk;
  52 };
  53
  54 static
  55 int at24c_eeprom_event(I2CSlave *s, enum i2c_event event)
  56 {
  57     EEPROMState *ee = container_of(s, EEPROMState, parent_obj);
  58
  59     switch (event) {
  60     case I2C_START_SEND:
  61     case I2C_START_RECV:
  62     case I2C_FINISH:
  63         ee->haveaddr = 0;
  64         DPRINTK("clear\n");
  65         if (ee->blk && ee->changed) {
  66             int len = blk_pwrite(ee->blk, 0, ee->mem, ee->rsize, 0);
  67             if (len != ee->rsize) {
  68                 ERR(TYPE_AT24C_EE
  69                         " : failed to write backing file\n");
  70             }
  71             DPRINTK("Wrote to backing file\n");
  72         }
  73         ee->changed = false;
  74         break;
  75     case I2C_NACK:
  76         break;
  77     }
  78     return 0;
  79 }
  80
  81 static
  82 uint8_t at24c_eeprom_recv(I2CSlave *s)
  83 {
  84     EEPROMState *ee = AT24C_EE(s);
  85     uint8_t ret;
  86
  87     ret = ee->mem[ee->cur];
  88
  89     ee->cur = (ee->cur + 1u) % ee->rsize;
  90     DPRINTK("Recv %02x %c\n", ret, ret);
  91
  92     return ret;
  93 }
  94
  95 static
  96 int at24c_eeprom_send(I2CSlave *s, uint8_t data)
  97 {
  98     EEPROMState *ee = AT24C_EE(s);
  99
 100     if (ee->haveaddr < 2) {
 101         ee->cur <<= 8;
 102         ee->cur |= data;
 103         ee->haveaddr++;
 104         if (ee->haveaddr == 2) {
 105             ee->cur %= ee->rsize;
 106             DPRINTK("Set pointer %04x\n", ee->cur);
 107         }
 108
 109     } else {
 110         if (ee->writable) {
 111             DPRINTK("Send %02x\n", data);
 112             ee->mem[ee->cur] = data;
 113             ee->changed = true;
 114         } else {
 115             DPRINTK("Send error %02x read-only\n", data);
 116         }
 117         ee->cur = (ee->cur + 1u) % ee->rsize;
 118
 119     }
 120
 121     return 0;
 122 }
 123
 124 static void at24c_eeprom_realize(DeviceState *dev, Error **errp)
 125 {
 126     EEPROMState *ee = AT24C_EE(dev);
 127
 128     if (ee->blk) {
 129         int64_t len = blk_getlength(ee->blk);
 130
 131         if (len != ee->rsize) {
 132             error_setg(errp, "%s: Backing file size %" PRId64 " != %u",
 133                        TYPE_AT24C_EE, len, ee->rsize);
 134             return;
 135         }
 136
 137         if (blk_set_perm(ee->blk, BLK_PERM_CONSISTENT_READ | BLK_PERM_WRITE,
 138                          BLK_PERM_ALL, &error_fatal) < 0)
 139         {
 140             error_setg(errp, "%s: Backing file incorrect permission",
 141                        TYPE_AT24C_EE);
 142             return;
 143         }
 144     }
 145
 146     ee->mem = g_malloc0(ee->rsize);
 147 }
 148
 149 static
 150 void at24c_eeprom_reset(DeviceState *state)
 151 {
 152     EEPROMState *ee = AT24C_EE(state);
 153
 154     ee->changed = false;
 155     ee->cur = 0;
 156     ee->haveaddr = 0;
 157
 158     memset(ee->mem, 0, ee->rsize);
 159
 160     if (ee->blk) {
 161         int len = blk_pread(ee->blk, 0, ee->mem, ee->rsize);
 162
 163         if (len != ee->rsize) {
 164             ERR(TYPE_AT24C_EE
 165                     " : Failed initial sync with backing file\n");
 166         }
 167         DPRINTK("Reset read backing file\n");
 168     }
 169 }
 170
 171 static Property at24c_eeprom_props[] = {
 172     DEFINE_PROP_UINT32("rom-size", EEPROMState, rsize, 0),
 173     DEFINE_PROP_BOOL("writable", EEPROMState, writable, true),
 174     DEFINE_PROP_DRIVE("drive", EEPROMState, blk),
 175     DEFINE_PROP_END_OF_LIST()
 176 };
 177
 178 static
 179 void at24c_eeprom_class_init(ObjectClass *klass, void *data)
 180 {
 181     DeviceClass *dc = DEVICE_CLASS(klass);
 182     I2CSlaveClass *k = I2C_SLAVE_CLASS(klass);
 183
 184     dc->realize = &at24c_eeprom_realize;
 185     k->event = &at24c_eeprom_event;
 186     k->recv = &at24c_eeprom_recv;
 187     k->send = &at24c_eeprom_send;
 188
 189     device_class_set_props(dc, at24c_eeprom_props);
 190     dc->reset = at24c_eeprom_reset;
 191 }
 192
 193 static
 194 const TypeInfo at24c_eeprom_type = {
 195     .name = TYPE_AT24C_EE,
 196     .parent = TYPE_I2C_SLAVE,
 197     .instance_size = sizeof(EEPROMState),
 198     .class_size = sizeof(I2CSlaveClass),
 199     .class_init = at24c_eeprom_class_init,
 200 };
 201
 202 static void at24c_eeprom_register(void)
 203 {
 204     type_register_static(&at24c_eeprom_type);
 205 }
 206
 207 type_init(at24c_eeprom_register)