drivers/media/common/saa7146_i2c.c

   1 #include <media/saa7146_vv.h>
   2
   3 static u32 saa7146_i2c_func(struct i2c_adapter *adapter)
   4 {
   5 //fm    DEB_I2C(("'%s'.\n", adapter->name));
   6
   7         return    I2C_FUNC_I2C
   8                 | I2C_FUNC_SMBUS_QUICK
   9                 | I2C_FUNC_SMBUS_READ_BYTE      | I2C_FUNC_SMBUS_WRITE_BYTE
  10                 | I2C_FUNC_SMBUS_READ_BYTE_DATA | I2C_FUNC_SMBUS_WRITE_BYTE_DATA;
  11 }
  12
  13 /* this function returns the status-register of our i2c-device */
  14 static inline u32 saa7146_i2c_status(struct saa7146_dev *dev)
  15 {
  16         u32 iicsta = saa7146_read(dev, I2C_STATUS);
  17 /*
  18         DEB_I2C(("status: 0x%08x\n",iicsta));
  19 */
  20         return iicsta;
  21 }
  22
  23 /* this function runs through the i2c-messages and prepares the data to be
  24    sent through the saa7146. have a look at the specifications p. 122 ff
  25    to understand this. it returns the number of u32s to send, or -1
  26    in case of an error. */
  27 static int saa7146_i2c_msg_prepare(const struct i2c_msg *m, int num, u32 *op)
  28 {
  29         int h1, h2;
  30         int i, j, addr;
  31         int mem = 0, op_count = 0;
  32
  33         /* first determine size of needed memory */
  34         for(i = 0; i < num; i++) {
  35                 mem += m[i].len + 1;
  36         }
  37
  38         /* worst case: we need one u32 for three bytes to be send
  39            plus one extra byte to address the device */
  40         mem = 1 + ((mem-1) / 3);
  41
  42         /* we assume that op points to a memory of at least SAA7146_I2C_MEM bytes
  43            size. if we exceed this limit... */
  44         if ( (4*mem) > SAA7146_I2C_MEM ) {
  45 //fm            DEB_I2C(("cannot prepare i2c-message.\n"));
  46                 return -ENOMEM;
  47         }
  48
  49         /* be careful: clear out the i2c-mem first */
  50         memset(op,0,sizeof(u32)*mem);
  51
  52         /* loop through all messages */
  53         for(i = 0; i < num; i++) {
  54
  55                 /* insert the address of the i2c-slave.
  56                    note: we get 7 bit i2c-addresses,
  57                    so we have to perform a translation */
  58                 addr = (m[i].addr*2) + ( (0 != (m[i].flags & I2C_M_RD)) ? 1 : 0);
  59                 h1 = op_count/3; h2 = op_count%3;
  60                 op[h1] |= (         (u8)addr << ((3-h2)*8));
  61                 op[h1] |= (SAA7146_I2C_START << ((3-h2)*2));
  62                 op_count++;
  63
  64                 /* loop through all bytes of message i */
  65                 for(j = 0; j < m[i].len; j++) {
  66                         /* insert the data bytes */
  67                         h1 = op_count/3; h2 = op_count%3;
  68                         op[h1] |= ( (u32)((u8)m[i].buf[j]) << ((3-h2)*8));
  69                         op[h1] |= (       SAA7146_I2C_CONT << ((3-h2)*2));
  70                         op_count++;
  71                 }
  72
  73         }
  74
  75         /* have a look at the last byte inserted:
  76           if it was: ...CONT change it to ...STOP */
  77         h1 = (op_count-1)/3; h2 = (op_count-1)%3;
  78         if ( SAA7146_I2C_CONT == (0x3 & (op[h1] >> ((3-h2)*2))) ) {
  79                 op[h1] &= ~(0x2 << ((3-h2)*2));
  80                 op[h1] |= (SAA7146_I2C_STOP << ((3-h2)*2));
  81         }
  82
  83         /* return the number of u32s to send */
  84         return mem;
  85 }
  86
  87 /* this functions loops through all i2c-messages. normally, it should determine
  88    which bytes were read through the adapter and write them back to the corresponding
  89    i2c-message. but instead, we simply write back all bytes.
  90    fixme: this could be improved. */
  91 static int saa7146_i2c_msg_cleanup(const struct i2c_msg *m, int num, u32 *op)
  92 {
  93         int i, j;
  94         int op_count = 0;
  95
  96         /* loop through all messages */
  97         for(i = 0; i < num; i++) {
  98
  99                 op_count++;
 100
 101                 /* loop throgh all bytes of message i */
 102                 for(j = 0; j < m[i].len; j++) {
 103                         /* write back all bytes that could have been read */
 104                         m[i].buf[j] = (op[op_count/3] >> ((3-(op_count%3))*8));
 105                         op_count++;
 106                 }
 107         }
 108
 109         return 0;
 110 }
 111
 112 /* this functions resets the i2c-device and returns 0 if everything was fine, otherwise -1 */
 113 static int saa7146_i2c_reset(struct saa7146_dev *dev)
 114 {
 115         /* get current status */
 116         u32 status = saa7146_i2c_status(dev);
 117
 118         /* clear registers for sure */
 119         saa7146_write(dev, I2C_STATUS, dev->i2c_bitrate);
 120         saa7146_write(dev, I2C_TRANSFER, 0);
 121
 122         /* check if any operation is still in progress */
 123         if ( 0 != ( status & SAA7146_I2C_BUSY) ) {
 124
 125                 /* yes, kill ongoing operation */
 126                 DEB_I2C(("busy_state detected.\n"));
 127
 128                 /* set "ABORT-OPERATION"-bit (bit 7)*/
 129                 saa7146_write(dev, I2C_STATUS, (dev->i2c_bitrate | MASK_07));
 130                 saa7146_write(dev, MC2, (MASK_00 | MASK_16));
 131                 msleep(SAA7146_I2C_DELAY);
 132
 133                 /* clear all error-bits pending; this is needed because p.123, note 1 */
 134                 saa7146_write(dev, I2C_STATUS, dev->i2c_bitrate);
 135                 saa7146_write(dev, MC2, (MASK_00 | MASK_16));
 136                 msleep(SAA7146_I2C_DELAY);
 137         }
 138
 139         /* check if any error is (still) present. (this can be necessary because p.123, note 1) */
 140         status = saa7146_i2c_status(dev);
 141
 142         if ( dev->i2c_bitrate != status ) {
 143
 144                 DEB_I2C(("error_state detected. status:0x%08x\n",status));
 145
 146                 /* Repeat the abort operation. This seems to be necessary
 147                    after serious protocol errors caused by e.g. the SAA7740 */
 148                 saa7146_write(dev, I2C_STATUS, (dev->i2c_bitrate | MASK_07));
 149                 saa7146_write(dev, MC2, (MASK_00 | MASK_16));
 150                 msleep(SAA7146_I2C_DELAY);
 151
 152                 /* clear all error-bits pending */
 153                 saa7146_write(dev, I2C_STATUS, dev->i2c_bitrate);
 154                 saa7146_write(dev, MC2, (MASK_00 | MASK_16));
 155                 msleep(SAA7146_I2C_DELAY);
 156
 157                 /* the data sheet says it might be necessary to clear the status
 158                    twice after an abort */
 159                 saa7146_write(dev, I2C_STATUS, dev->i2c_bitrate);
 160                 saa7146_write(dev, MC2, (MASK_00 | MASK_16));
 161                 msleep(SAA7146_I2C_DELAY);
 162         }
 163
 164         /* if any error is still present, a fatal error has occured ... */
 165         status = saa7146_i2c_status(dev);
 166         if ( dev->i2c_bitrate != status ) {
 167                 DEB_I2C(("fatal error. status:0x%08x\n",status));
 168                 return -1;
 169         }
 170
 171         return 0;
 172 }
 173
 174 /* this functions writes out the data-byte 'dword' to the i2c-device.
 175    it returns 0 if ok, -1 if the transfer failed, -2 if the transfer
 176    failed badly (e.g. address error) */
 177 static int saa7146_i2c_writeout(struct saa7146_dev *dev, u32* dword, int short_delay)
 178 {
 179         u32 status = 0, mc2 = 0;
 180         int trial = 0;
 181         unsigned long timeout;
 182
 183         /* write out i2c-command */
 184         DEB_I2C(("before: 0x%08x (status: 0x%08x), %d\n",*dword,saa7146_read(dev, I2C_STATUS), dev->i2c_op));
 185
 186         if( 0 != (SAA7146_USE_I2C_IRQ & dev->ext->flags)) {
 187
 188                 saa7146_write(dev, I2C_STATUS,   dev->i2c_bitrate);
 189                 saa7146_write(dev, I2C_TRANSFER, *dword);
 190
 191                 dev->i2c_op = 1;
 192                 SAA7146_IER_ENABLE(dev, MASK_16|MASK_17);
 193                 saa7146_write(dev, MC2, (MASK_00 | MASK_16));
 194
 195                 wait_event_interruptible(dev->i2c_wq, dev->i2c_op == 0);
 196                 if (signal_pending (current)) {
 197                         /* a signal arrived */
 198                         return -ERESTARTSYS;
 199                 }
 200                 status = saa7146_read(dev, I2C_STATUS);
 201         } else {
 202                 saa7146_write(dev, I2C_STATUS,   dev->i2c_bitrate);
 203                 saa7146_write(dev, I2C_TRANSFER, *dword);
 204                 saa7146_write(dev, MC2, (MASK_00 | MASK_16));
 205
 206                 /* do not poll for i2c-status before upload is complete */
 207                 timeout = jiffies + HZ/100 + 1; /* 10ms */
 208                 while(1) {
 209                         mc2 = (saa7146_read(dev, MC2) & 0x1);
 210                         if( 0 != mc2 ) {
 211                                 break;
 212                         }
 213                         if (time_after(jiffies,timeout)) {
 214                                 printk(KERN_WARNING "saa7146_i2c_writeout: timed out waiting for MC2\n");
 215                                 return -EIO;
 216                         }
 217                 }
 218                 /* wait until we get a transfer done or error */
 219                 timeout = jiffies + HZ/100 + 1; /* 10ms */
 220                 while(1) {
 221                         /**
 222                          *  first read usually delivers bogus results...
 223                          */
 224                         saa7146_i2c_status(dev);
 225                         status = saa7146_i2c_status(dev);
 226                         if ((status & 0x3) != 1)
 227                                 break;
 228                         if (time_after(jiffies,timeout)) {
 229                                 /* this is normal when probing the bus
 230                                  * (no answer from nonexisistant device...)
 231                                  */
 232                                 DEB_I2C(("saa7146_i2c_writeout: timed out waiting for end of xfer\n"));
 233                                 return -EIO;
 234                         }
 235                         if ((++trial < 20) && short_delay)
 236                                 udelay(10);
 237                         else
 238                         msleep(1);
 239                 }
 240         }
 241
 242         /* give a detailed status report */
 243         if ( 0 != (status & SAA7146_I2C_ERR)) {
 244
 245                 if( 0 != (status & SAA7146_I2C_SPERR) ) {
 246                         DEB_I2C(("error due to invalid start/stop condition.\n"));
 247                 }
 248                 if( 0 != (status & SAA7146_I2C_DTERR) ) {
 249                         DEB_I2C(("error in data transmission.\n"));
 250                 }
 251                 if( 0 != (status & SAA7146_I2C_DRERR) ) {
 252                         DEB_I2C(("error when receiving data.\n"));
 253                 }
 254                 if( 0 != (status & SAA7146_I2C_AL) ) {
 255                         DEB_I2C(("error because arbitration lost.\n"));
 256                 }
 257
 258                 /* we handle address-errors here */
 259                 if( 0 != (status & SAA7146_I2C_APERR) ) {
 260                         DEB_I2C(("error in address phase.\n"));
 261                         return -EREMOTEIO;
 262                 }
 263
 264                 return -EIO;
 265         }
 266
 267         /* read back data, just in case we were reading ... */
 268         *dword = saa7146_read(dev, I2C_TRANSFER);
 269
 270         DEB_I2C(("after: 0x%08x\n",*dword));
 271         return 0;
 272 }
 273
 274 int saa7146_i2c_transfer(struct saa7146_dev *dev, const struct i2c_msg *msgs, int num, int retries)
 275 {
 276         int i = 0, count = 0;
 277         u32* buffer = dev->d_i2c.cpu_addr;
 278         int err = 0;
 279         int address_err = 0;
 280         int short_delay = 0;
 281
 282         if (down_interruptible (&dev->i2c_lock))
 283                 return -ERESTARTSYS;
 284
 285         for(i=0;i<num;i++) {
 286                 DEB_I2C(("msg:%d/%d\n",i+1,num));
 287         }
 288
 289         /* prepare the message(s), get number of u32s to transfer */
 290         count = saa7146_i2c_msg_prepare(msgs, num, buffer);
 291         if ( 0 > count ) {
 292                 err = -1;
 293                 goto out;
 294         }
 295
 296         if ( count > 3 || 0 != (SAA7146_I2C_SHORT_DELAY & dev->ext->flags) )
 297                 short_delay = 1;
 298
 299         do {
 300                 /* reset the i2c-device if necessary */
 301                 err = saa7146_i2c_reset(dev);
 302                 if ( 0 > err ) {
 303                         DEB_I2C(("could not reset i2c-device.\n"));
 304                         goto out;
 305                 }
 306
 307                 /* write out the u32s one after another */
 308                 for(i = 0; i < count; i++) {
 309                         err = saa7146_i2c_writeout(dev, &buffer[i], short_delay);
 310                         if ( 0 != err) {
 311                                 /* this one is unsatisfying: some i2c slaves on some
 312                                    dvb cards don't acknowledge correctly, so the saa7146
 313                                    thinks that an address error occured. in that case, the
 314                                    transaction should be retrying, even if an address error
 315                                    occured. analog saa7146 based cards extensively rely on
 316                                    i2c address probing, however, and address errors indicate that a
 317                                    device is really *not* there. retrying in that case
 318                                    increases the time the device needs to probe greatly, so
 319                                    it should be avoided. because of the fact, that only
 320                                    analog based cards use irq based i2c transactions (for dvb
 321                                    cards, this screwes up other interrupt sources), we bail out
 322                                    completely for analog cards after an address error and trust
 323                                    the saa7146 address error detection. */
 324                                 if ( -EREMOTEIO == err ) {
 325                                         if( 0 != (SAA7146_USE_I2C_IRQ & dev->ext->flags)) {
 326                                                 goto out;
 327                                         }
 328                                         address_err++;
 329                                 }
 330                                 DEB_I2C(("error while sending message(s). starting again.\n"));
 331                                 break;
 332                         }
 333                 }
 334                 if( 0 == err ) {
 335                         err = num;
 336                         break;
 337                 }
 338
 339                 /* delay a bit before retrying */
 340                 msleep(10);
 341
 342         } while (err != num && retries--);
 343
 344         /* if every retry had an address error, exit right away */
 345         if (address_err == retries) {
 346                 goto out;
 347         }
 348
 349         /* if any things had to be read, get the results */
 350         if ( 0 != saa7146_i2c_msg_cleanup(msgs, num, buffer)) {
 351                 DEB_I2C(("could not cleanup i2c-message.\n"));
 352                 err = -1;
 353                 goto out;
 354         }
 355
 356         /* return the number of delivered messages */
 357         DEB_I2C(("transmission successful. (msg:%d).\n",err));
 358 out:
 359         /* another bug in revision 0: the i2c-registers get uploaded randomly by other
 360            uploads, so we better clear them out before continueing */
 361         if( 0 == dev->revision ) {
 362                 u32 zero = 0;
 363                 saa7146_i2c_reset(dev);
 364                 if( 0 != saa7146_i2c_writeout(dev, &zero, short_delay)) {
 365                         INFO(("revision 0 error. this should never happen.\n"));
 366                 }
 367         }
 368
 369         up(&dev->i2c_lock);
 370         return err;
 371 }
 372
 373 /* utility functions */
 374 static int saa7146_i2c_xfer(struct i2c_adapter* adapter, struct i2c_msg *msg, int num)
 375 {
 376         struct saa7146_dev* dev = i2c_get_adapdata(adapter);
 377
 378         /* use helper function to transfer data */
 379         return saa7146_i2c_transfer(dev, msg, num, adapter->retries);
 380 }
 381
 382
 383 /*****************************************************************************/
 384 /* i2c-adapter helper functions                                              */
 385 #include <linux/i2c-id.h>
 386
 387 /* exported algorithm data */
 388 static struct i2c_algorithm saa7146_algo = {
 389         .master_xfer    = saa7146_i2c_xfer,
 390         .functionality  = saa7146_i2c_func,
 391 };
 392
 393 int saa7146_i2c_adapter_prepare(struct saa7146_dev *dev, struct i2c_adapter *i2c_adapter, u32 bitrate)
 394 {
 395         DEB_EE(("bitrate: 0x%08x\n",bitrate));
 396
 397         /* enable i2c-port pins */
 398         saa7146_write(dev, MC1, (MASK_08 | MASK_24));
 399
 400         dev->i2c_bitrate = bitrate;
 401         saa7146_i2c_reset(dev);
 402
 403         if( NULL != i2c_adapter ) {
 404                 BUG_ON(!i2c_adapter->class);
 405                 i2c_set_adapdata(i2c_adapter,dev);
 406                 i2c_adapter->algo          = &saa7146_algo;
 407                 i2c_adapter->algo_data     = NULL;
 408                 i2c_adapter->id            = I2C_HW_SAA7146;
 409                 i2c_adapter->timeout = SAA7146_I2C_TIMEOUT;
 410                 i2c_adapter->retries = SAA7146_I2C_RETRIES;
 411         }
 412
 413         return 0;
 414 }