On 04/04/2014 03:08 AM, Shaveta Leekha wrote: > Most of the I2C slaves support accesses in the typical style > viz.read/write series of bytes at particular address offset.
viz? > These transactions are currently supportd in the > i2c driver using i2c_read and i2c_write APIs. I2C EEPROMs, > RTC, etc fall in this category. > The transactions look like:" > START:Address:Tx:Offset:RESTART:Address[0..4]:Tx/Rx:data[0..n]:STOP" > > However there are certain devices which support accesses in > terms of the transactions as follows: > "START:Address:Tx:Txdata[0..n1]:Clock_stretching: > RESTART:Address:Rx:data[0..n2]" > > The Txdata is typically a command and some associated data, > similarly Rxdata could be command status plus some data received > as a response to the command sent. > i2c_read() function has been modified to handle > both types of transactions: > the one that writes only offset/address before read and other that > writes some bytes(more than 4 bytes) before read Please rephrase this sentence. It is not very clear. > > To handle the case: > Negative equivalent of length has been passed and > interpreted accordinglt and txdata is being passed in > rxdata buffer This belongs to inline comments. You should explain more in detail in the comment. Commit message helps but it is hard to find in long term. > > Signed-off-by: Shaveta Leekha <[email protected]> > Signed-off-by: Poonam Aggrwal <[email protected]> > --- > drivers/i2c/fsl_i2c.c | 40 +++++++++++++++++++++++++++++++--------- > 1 files changed, 31 insertions(+), 9 deletions(-) > > diff --git a/drivers/i2c/fsl_i2c.c b/drivers/i2c/fsl_i2c.c > index 291ad94..14c66d0 100644 > --- a/drivers/i2c/fsl_i2c.c > +++ b/drivers/i2c/fsl_i2c.c > @@ -424,17 +424,39 @@ fsl_i2c_read(struct i2c_adapter *adap, u8 dev, uint > addr, int alen, u8 *data, > int i = -1; /* signal error */ > u8 *a = (u8*)&addr; > > - if (i2c_wait4bus(adap) < 0) > - return -1; You don't need to move these two lines. > + if (alen < 0) { You need to put a lot of comment to explain here. > + int len = alen * -1; You don't really need a new variable here. Even you do, put the variable declaration to the beginning of the function. > + if (i2c_wait4bus(adap) < 0) > + return -1; > + > + /* Generate a START and send the Address and > + * the Tx Bytes to the slave. > + * "START: Address: Write bytes wdata[wlength]" > + * It supports writing any number of bytes in contrast > + * to the else part, which supports writing address offset > + * of upto 4 bytes only. > + */ > + if (i2c_write_addr(adap, dev, I2C_WRITE_BIT, 0) != 0) > + i = __i2c_write(adap, data, len); And explain how you use "data". York _______________________________________________ U-Boot mailing list [email protected] http://lists.denx.de/mailman/listinfo/u-boot
