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 shaveta@freescale.com Signed-off-by: Poonam Aggrwal poonam.aggrwal@freescale.com
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