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authorDavid Brownell <david-b@pacbell.net>2007-09-09 16:29:14 -0400
committerJean Delvare <khali@hyperion.delvare>2007-09-09 16:29:14 -0400
commit939bc4943d0483961edc45b63a7d27b4ffe547e3 (patch)
tree4fb51849830e0bc3ef4e6534117fdb216a29406d /drivers/i2c/algos/i2c-algo-bit.c
parent51e5709ad46127da9476f31336113b5401f94dba (diff)
i2c-algo-bit: Read block data bugfix
This fixes a bug in the way i2c-algo-bit handles I2C_M_RECV_LEN, used to implement i2c_smbus_read_block_data(). Previously, in the absence of PEC (rarely used!) it would NAK the "length" byte: S addr Rd [A] [length] NA That prevents the subsequent data bytes from being read: S addr Rd [A] [length] { A [data] }* NA The primary fix just reorders two code blocks, so the length used in the "should I NAK now?" check incorporates the data which it just read from the slave device. However, that move also highlighted other fault handling glitches. This fixes those by abstracting the RX path ack/nak logic, so it can be used in more than one location. Also, a few CodingStyle issues were also resolved. Signed-off-by: David Brownell <dbrownell@users.sourceforge.net> Signed-off-by: Jean Delvare <khali@linux-fr.org>
Diffstat (limited to 'drivers/i2c/algos/i2c-algo-bit.c')
-rw-r--r--drivers/i2c/algos/i2c-algo-bit.c52
1 files changed, 32 insertions, 20 deletions
diff --git a/drivers/i2c/algos/i2c-algo-bit.c b/drivers/i2c/algos/i2c-algo-bit.c
index 8a5f5825bb72..7f0a0a62cf60 100644
--- a/drivers/i2c/algos/i2c-algo-bit.c
+++ b/drivers/i2c/algos/i2c-algo-bit.c
@@ -357,13 +357,29 @@ static int sendbytes(struct i2c_adapter *i2c_adap, struct i2c_msg *msg)
357 return wrcount; 357 return wrcount;
358} 358}
359 359
360static int acknak(struct i2c_adapter *i2c_adap, int is_ack)
361{
362 struct i2c_algo_bit_data *adap = i2c_adap->algo_data;
363
364 /* assert: sda is high */
365 if (is_ack) /* send ack */
366 setsda(adap, 0);
367 udelay((adap->udelay + 1) / 2);
368 if (sclhi(adap) < 0) { /* timeout */
369 dev_err(&i2c_adap->dev, "readbytes: ack/nak timeout\n");
370 return -ETIMEDOUT;
371 }
372 scllo(adap);
373 return 0;
374}
375
360static int readbytes(struct i2c_adapter *i2c_adap, struct i2c_msg *msg) 376static int readbytes(struct i2c_adapter *i2c_adap, struct i2c_msg *msg)
361{ 377{
362 int inval; 378 int inval;
363 int rdcount=0; /* counts bytes read */ 379 int rdcount=0; /* counts bytes read */
364 struct i2c_algo_bit_data *adap = i2c_adap->algo_data;
365 unsigned char *temp = msg->buf; 380 unsigned char *temp = msg->buf;
366 int count = msg->len; 381 int count = msg->len;
382 const unsigned flags = msg->flags;
367 383
368 while (count > 0) { 384 while (count > 0) {
369 inval = i2c_inb(i2c_adap); 385 inval = i2c_inb(i2c_adap);
@@ -377,28 +393,12 @@ static int readbytes(struct i2c_adapter *i2c_adap, struct i2c_msg *msg)
377 temp++; 393 temp++;
378 count--; 394 count--;
379 395
380 if (msg->flags & I2C_M_NO_RD_ACK) {
381 bit_dbg(2, &i2c_adap->dev, "i2c_inb: 0x%02x\n",
382 inval);
383 continue;
384 }
385
386 /* assert: sda is high */
387 if (count) /* send ack */
388 setsda(adap, 0);
389 udelay((adap->udelay + 1) / 2);
390 bit_dbg(2, &i2c_adap->dev, "i2c_inb: 0x%02x %s\n", inval,
391 count ? "A" : "NA");
392 if (sclhi(adap)<0) { /* timeout */
393 dev_err(&i2c_adap->dev, "readbytes: timeout at ack\n");
394 return -ETIMEDOUT;
395 };
396 scllo(adap);
397
398 /* Some SMBus transactions require that we receive the 396 /* Some SMBus transactions require that we receive the
399 transaction length as the first read byte. */ 397 transaction length as the first read byte. */
400 if (rdcount == 1 && (msg->flags & I2C_M_RECV_LEN)) { 398 if (rdcount == 1 && (flags & I2C_M_RECV_LEN)) {
401 if (inval <= 0 || inval > I2C_SMBUS_BLOCK_MAX) { 399 if (inval <= 0 || inval > I2C_SMBUS_BLOCK_MAX) {
400 if (!(flags & I2C_M_NO_RD_ACK))
401 acknak(i2c_adap, 0);
402 dev_err(&i2c_adap->dev, "readbytes: invalid " 402 dev_err(&i2c_adap->dev, "readbytes: invalid "
403 "block length (%d)\n", inval); 403 "block length (%d)\n", inval);
404 return -EREMOTEIO; 404 return -EREMOTEIO;
@@ -409,6 +409,18 @@ static int readbytes(struct i2c_adapter *i2c_adap, struct i2c_msg *msg)
409 count += inval; 409 count += inval;
410 msg->len += inval; 410 msg->len += inval;
411 } 411 }
412
413 bit_dbg(2, &i2c_adap->dev, "readbytes: 0x%02x %s\n",
414 inval,
415 (flags & I2C_M_NO_RD_ACK)
416 ? "(no ack/nak)"
417 : (count ? "A" : "NA"));
418
419 if (!(flags & I2C_M_NO_RD_ACK)) {
420 inval = acknak(i2c_adap, count);
421 if (inval < 0)
422 return inval;
423 }
412 } 424 }
413 return rdcount; 425 return rdcount;
414} 426}