[U-Boot] [PATCH v3 1/6] dm: i2c: Add u8 read/write i2c functions

[Keerthy]

On Tuesday 20 September 2016 05:23 PM, Simon Glass wrote:
> Hi,
>
> On 19 September 2016 at 00:17, Keerthy <j-keerthy at ti.com> wrote:
>> Add u8 i2c read/write hooks.
>>
>> Signed-off-by: Keerthy <j-keerthy at ti.com>
>> ---
>>  drivers/i2c/i2c-uclass.c | 10 ++++++++++
>>  include/i2c.h            | 24 ++++++++++++++++++++++++
>>  2 files changed, 34 insertions(+)
>>
>> diff --git a/drivers/i2c/i2c-uclass.c b/drivers/i2c/i2c-uclass.c
>> index dbd3789..6ce5d9a 100644
>> --- a/drivers/i2c/i2c-uclass.c
>> +++ b/drivers/i2c/i2c-uclass.c
>> @@ -231,6 +231,16 @@ int dm_i2c_reg_write(struct udevice *dev, uint offset, uint value)
>>         return dm_i2c_write(dev, offset, &val, 1);
>>  }
>>
>> +int dm_i2c_u8_read(struct udevice *dev, uint offset, u8 *val)
>> +{
>> +       return dm_i2c_read(dev, offset, val, 1);
>> +}
>> +
>> +int dm_i2c_u8_write(struct udevice *dev, uint offset, u8 *val)
>> +{
>> +       return dm_i2c_write(dev, offset, val, 1);
>> +}
>
> These look almost the same as dm_i2c_reg_read/write(), but IMO those
> are easier to use since they don't require a pointer to be passed. How
> do you intend to use these two new functions?

Simon,

I see a kind of issue in the current implementation of
int dm_i2c_reg_read(struct udevice *dev, uint offset)
int dm_i2c_reg_write(struct udevice *dev, uint offset, uint value)

In the current set up my need is to read and then write a 1 byte I2C 
register. It is best to have consistency with read and write.
In the current case(dm_i2c_reg_read/write) i read an integer and now 
when i want to write i need to convert it to an unsigned integer.

Instead of all this i made a patch which keeps u8 across read and write:

int dm_i2c_reg_read(struct udevice *dev, uint offset, u8 *val)
returns error/success with the return value and value is passed by 
reference in val variable.

int dm_i2c_reg_write(struct udevice *dev, uint offset, u8 *val)
returns error/success using the return value and the value to be written 
is sent in val.

Regards,
Keerthy


>
>> +
>>  /**
>>   * i2c_probe_chip() - probe for a chip on a bus
>>   *
>> diff --git a/include/i2c.h b/include/i2c.h
>> index d500445..c3059ad 100644
>> --- a/include/i2c.h
>> +++ b/include/i2c.h
>> @@ -191,6 +191,30 @@ int dm_i2c_reg_read(struct udevice *dev, uint offset);
>>  int dm_i2c_reg_write(struct udevice *dev, uint offset, unsigned int val);
>>
>>  /**
>> + * dm_i2c_u8_read() - Read a byte value from an I2C register
>> + *
>> + * This reads a single value from the given address in an I2C chip
>> + *
>> + * @dev:        Device to use for transfer
>> + * @addr:       Address to read from
>> + * @val:       Value read is stored in val
>> + * @return 0 for success, -ve on error
>> + */
>> +int dm_i2c_u8_read(struct udevice *dev, uint offset, u8 *val);
>> +
>> +/**
>> + * dm_i2c_u8_write() - Write a byte value to an I2C register
>> + *
>> + * This writes a single value to the given address in an I2C chip
>> + *
>> + * @dev:        Device to use for transfer
>> + * @addr:       Address to write to
>> + * @val:        Value to write
>> + * @return 0 on success, -ve on error
>> + */
>> +int dm_i2c_u8_write(struct udevice *dev, uint offset, u8 *val);
>> +
>> +/**
>>   * dm_i2c_xfer() - Transfer messages over I2C
>>   *
>>   * This transfers a raw message. It is best to use dm_i2c_reg_read/write()
>> --
>> 1.9.1
>
> Regards,
> Simon
>