linux-kernel - Re: [PATCH] at24: extend driver to allow writing via i2c_smbus_write_byte

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Date:	Wed, 27 Mar 2013 13:27:38 +0100
From:	Christian Gmeiner <christian.gmeiner@...il.com>
To:	Wolfram Sang <w.sang@...gutronix.de>
Cc:	linux-i2c@...r.kernel.org, LKML <linux-kernel@...r.kernel.org>,
	Christian Gmeiner <c.gmeiner@...hmann.info>
Subject: Re: [PATCH] at24: extend driver to allow writing via i2c_smbus_write_byte_data

2013/1/24 Wolfram Sang <w.sang@...gutronix.de>:
> On Wed, Dec 19, 2012 at 05:07:09PM +0100, Christian Gmeiner wrote:
>> I have a at24 EEPROM connected via i2c bus provided by ISCH i2c
>> bus driver. This bus driver does not support
>> I2C_FUNC_SMBUS_WRITE_I2C_BLOCK and so I was looking for a way
>> to be able to write the eeprom. This patch adds support for
>> I2C_SMBUS_BYTE_DATA writing via i2c_smbus_write_byte_data.
>> It is quite slow, but it works.
>>
>> Signed-off-by: Christian Gmeiner <christian.gmeiner@...il.com>
>> ---
>>  drivers/misc/eeprom/at24.c | 35 +++++++++++++++++++++++++++++------
>>  1 file changed, 29 insertions(+), 6 deletions(-)
>>
>> diff --git a/drivers/misc/eeprom/at24.c b/drivers/misc/eeprom/at24.c
>> index 2baeec5..723b411 100644
>> --- a/drivers/misc/eeprom/at24.c
>> +++ b/drivers/misc/eeprom/at24.c
>> @@ -56,6 +56,7 @@ struct at24_data {
>>       struct at24_platform_data chip;
>>       struct memory_accessor macc;
>>       int use_smbus;
>> +     int use_smbuse_write;
>
> Can't you use the same 'use_smbus' variable and do a similar switch-case
> as in the read function?
>

Sorry for the really late answer.

I am not sure if there exits some i2c buses which have different
access methods for read and write.
E.g. I2C_FUNC_SMBUS_WRITE_I2C_BLOCK and I2C_FUNC_SMBUS_READ_BYTE_DATA

If there will never be such a combination then I can reuse the same
'use_smbus' variable.

--
Christian Gmeiner, MSc
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