hw/smbus.c

   1 /*
   2  * QEMU SMBus device emulation.
   3  *
   4  * Copyright (c) 2007 CodeSourcery.
   5  * Written by Paul Brook
   6  *
   7  * This code is licenced under the LGPL.
   8  */
   9
  10 /* TODO: Implement PEC.  */
  11
  12 #include "hw.h"
  13 #include "i2c.h"
  14 #include "smbus.h"
  15
  16 //#define DEBUG_SMBUS 1
  17
  18 #ifdef DEBUG_SMBUS
  19 #define DPRINTF(fmt, args...) \
  20 do { printf("smbus(%02x): " fmt , dev->i2c.address, ##args); } while (0)
  21 #define BADF(fmt, args...) \
  22 do { fprintf(stderr, "smbus: error: " fmt , ##args); exit(1);} while (0)
  23 #else
  24 #define DPRINTF(fmt, args...) do {} while(0)
  25 #define BADF(fmt, args...) \
  26 do { fprintf(stderr, "smbus: error: " fmt , ##args);} while (0)
  27 #endif
  28
  29 enum {
  30     SMBUS_IDLE,
  31     SMBUS_WRITE_DATA,
  32     SMBUS_RECV_BYTE,
  33     SMBUS_READ_DATA,
  34     SMBUS_DONE,
  35     SMBUS_CONFUSED = -1
  36 };
  37
  38 static void smbus_do_quick_cmd(SMBusDevice *dev, int recv)
  39 {
  40     DPRINTF("Quick Command %d\n", recv);
  41     if (dev->quick_cmd)
  42         dev->quick_cmd(dev, recv);
  43 }
  44
  45 static void smbus_do_write(SMBusDevice *dev)
  46 {
  47     if (dev->data_len == 0) {
  48         smbus_do_quick_cmd(dev, 0);
  49     } else if (dev->data_len == 1) {
  50         DPRINTF("Send Byte\n");
  51         if (dev->send_byte) {
  52             dev->send_byte(dev, dev->data_buf[0]);
  53         }
  54     } else {
  55         dev->command = dev->data_buf[0];
  56         DPRINTF("Command %d len %d\n", dev->command, dev->data_len - 1);
  57         if (dev->write_data) {
  58             dev->write_data(dev, dev->command, dev->data_buf + 1,
  59                             dev->data_len - 1);
  60         }
  61     }
  62 }
  63
  64 static void smbus_i2c_event(i2c_slave *s, enum i2c_event event)
  65 {
  66     SMBusDevice *dev = (SMBusDevice *)s;
  67     switch (event) {
  68     case I2C_START_SEND:
  69         switch (dev->mode) {
  70         case SMBUS_IDLE:
  71             DPRINTF("Incoming data\n");
  72             dev->mode = SMBUS_WRITE_DATA;
  73             break;
  74         default:
  75             BADF("Unexpected send start condition in state %d\n", dev->mode);
  76             dev->mode = SMBUS_CONFUSED;
  77             break;
  78         }
  79         break;
  80
  81     case I2C_START_RECV:
  82         switch (dev->mode) {
  83         case SMBUS_IDLE:
  84             DPRINTF("Read mode\n");
  85             dev->mode = SMBUS_RECV_BYTE;
  86             break;
  87         case SMBUS_WRITE_DATA:
  88             if (dev->data_len == 0) {
  89                 BADF("Read after write with no data\n");
  90                 dev->mode = SMBUS_CONFUSED;
  91             } else {
  92                 if (dev->data_len > 1) {
  93                     smbus_do_write(dev);
  94                 } else {
  95                     dev->command = dev->data_buf[0];
  96                     DPRINTF("%02x: Command %d\n", dev->i2c.address,
  97                             dev->command);
  98                 }
  99                 DPRINTF("Read mode\n");
 100                 dev->data_len = 0;
 101                 dev->mode = SMBUS_READ_DATA;
 102             }
 103             break;
 104         default:
 105             BADF("Unexpected recv start condition in state %d\n", dev->mode);
 106             dev->mode = SMBUS_CONFUSED;
 107             break;
 108         }
 109         break;
 110
 111     case I2C_FINISH:
 112         switch (dev->mode) {
 113         case SMBUS_WRITE_DATA:
 114             smbus_do_write(dev);
 115             break;
 116         case SMBUS_RECV_BYTE:
 117             smbus_do_quick_cmd(dev, 1);
 118             break;
 119         case SMBUS_READ_DATA:
 120             BADF("Unexpected stop during receive\n");
 121             break;
 122         default:
 123             /* Nothing to do.  */
 124             break;
 125         }
 126         dev->mode = SMBUS_IDLE;
 127         dev->data_len = 0;
 128         break;
 129
 130     case I2C_NACK:
 131         switch (dev->mode) {
 132         case SMBUS_DONE:
 133             /* Nothing to do.  */
 134             break;
 135         case SMBUS_READ_DATA:
 136             dev->mode = SMBUS_DONE;
 137             break;
 138         default:
 139             BADF("Unexpected NACK in state %d\n", dev->mode);
 140             dev->mode = SMBUS_CONFUSED;
 141             break;
 142         }
 143     }
 144 }
 145
 146 static int smbus_i2c_recv(i2c_slave *s)
 147 {
 148     SMBusDevice *dev = (SMBusDevice *)s;
 149     int ret;
 150
 151     switch (dev->mode) {
 152     case SMBUS_RECV_BYTE:
 153         if (dev->receive_byte) {
 154             ret = dev->receive_byte(dev);
 155         } else {
 156             ret = 0;
 157         }
 158         DPRINTF("Receive Byte %02x\n", ret);
 159         dev->mode = SMBUS_DONE;
 160         break;
 161     case SMBUS_READ_DATA:
 162         if (dev->read_data) {
 163             ret = dev->read_data(dev, dev->command, dev->data_len);
 164             dev->data_len++;
 165         } else {
 166             ret = 0;
 167         }
 168         DPRINTF("Read data %02x\n", ret);
 169         break;
 170     default:
 171         BADF("Unexpected read in state %d\n", dev->mode);
 172         dev->mode = SMBUS_CONFUSED;
 173         ret = 0;
 174         break;
 175     }
 176     return ret;
 177 }
 178
 179 static int smbus_i2c_send(i2c_slave *s, uint8_t data)
 180 {
 181     SMBusDevice *dev = (SMBusDevice *)s;
 182     switch (dev->mode) {
 183     case SMBUS_WRITE_DATA:
 184         DPRINTF("Write data %02x\n", data);
 185         dev->data_buf[dev->data_len++] = data;
 186         break;
 187     default:
 188         BADF("Unexpected write in state %d\n", dev->mode);
 189         break;
 190     }
 191     return 0;
 192 }
 193
 194 SMBusDevice *smbus_device_init(i2c_bus *bus, int address, int size)
 195 {
 196     SMBusDevice *dev;
 197
 198     if (size < sizeof(SMBusDevice))
 199         hw_error("SMBus struct too small");
 200
 201     dev = (SMBusDevice *)i2c_slave_init(bus, address, size);
 202     dev->i2c.event = smbus_i2c_event;
 203     dev->i2c.recv = smbus_i2c_recv;
 204     dev->i2c.send = smbus_i2c_send;
 205
 206     return dev;
 207 }
 208
 209 /* Master device commands.  */
 210 void smbus_quick_command(i2c_bus *bus, int addr, int read)
 211 {
 212     i2c_start_transfer(bus, addr, read);
 213     i2c_end_transfer(bus);
 214 }
 215
 216 uint8_t smbus_receive_byte(i2c_bus *bus, int addr)
 217 {
 218     uint8_t data;
 219
 220     i2c_start_transfer(bus, addr, 1);
 221     data = i2c_recv(bus);
 222     i2c_nack(bus);
 223     i2c_end_transfer(bus);
 224     return data;
 225 }
 226
 227 void smbus_send_byte(i2c_bus *bus, int addr, uint8_t data)
 228 {
 229     i2c_start_transfer(bus, addr, 0);
 230     i2c_send(bus, data);
 231     i2c_end_transfer(bus);
 232 }
 233
 234 uint8_t smbus_read_byte(i2c_bus *bus, int addr, uint8_t command)
 235 {
 236     uint8_t data;
 237     i2c_start_transfer(bus, addr, 0);
 238     i2c_send(bus, command);
 239     i2c_start_transfer(bus, addr, 1);
 240     data = i2c_recv(bus);
 241     i2c_nack(bus);
 242     i2c_end_transfer(bus);
 243     return data;
 244 }
 245
 246 void smbus_write_byte(i2c_bus *bus, int addr, uint8_t command, uint8_t data)
 247 {
 248     i2c_start_transfer(bus, addr, 0);
 249     i2c_send(bus, command);
 250     i2c_send(bus, data);
 251     i2c_end_transfer(bus);
 252 }
 253
 254 uint16_t smbus_read_word(i2c_bus *bus, int addr, uint8_t command)
 255 {
 256     uint16_t data;
 257     i2c_start_transfer(bus, addr, 0);
 258     i2c_send(bus, command);
 259     i2c_start_transfer(bus, addr, 1);
 260     data = i2c_recv(bus);
 261     data |= i2c_recv(bus) << 8;
 262     i2c_nack(bus);
 263     i2c_end_transfer(bus);
 264     return data;
 265 }
 266
 267 void smbus_write_word(i2c_bus *bus, int addr, uint8_t command, uint16_t data)
 268 {
 269     i2c_start_transfer(bus, addr, 0);
 270     i2c_send(bus, command);
 271     i2c_send(bus, data & 0xff);
 272     i2c_send(bus, data >> 8);
 273     i2c_end_transfer(bus);
 274 }
 275
 276 int smbus_read_block(i2c_bus *bus, int addr, uint8_t command, uint8_t *data)
 277 {
 278     int len;
 279     int i;
 280
 281     i2c_start_transfer(bus, addr, 0);
 282     i2c_send(bus, command);
 283     i2c_start_transfer(bus, addr, 1);
 284     len = i2c_recv(bus);
 285     if (len > 32)
 286         len = 0;
 287     for (i = 0; i < len; i++)
 288         data[i] = i2c_recv(bus);
 289     i2c_nack(bus);
 290     i2c_end_transfer(bus);
 291     return len;
 292 }
 293
 294 void smbus_write_block(i2c_bus *bus, int addr, uint8_t command, uint8_t *data,
 295                        int len)
 296 {
 297     int i;
 298
 299     if (len > 32)
 300         len = 32;
 301
 302     i2c_start_transfer(bus, addr, 0);
 303     i2c_send(bus, command);
 304     i2c_send(bus, len);
 305     for (i = 0; i < len; i++)
 306         i2c_send(bus, data[i]);
 307     i2c_end_transfer(bus);
 308 }