Jean Delvare wrote:
> On Tue, 07 Jul 2009 11:38:46 +0000, Jonathan Cameron wrote:
>> Basically it's protocol is a standard smbus type write byte command
>> (address 0x19) followed by a delay (command specific) and then
>> a read of multiple bytes (number is command dependant.)
>>
>> Unfortunately the device doesn't seem do anything helpful like notify
>> you of how many bytes it is sending (as per smbus block read).
>>
>> I fear to make this work you'll need to write a kernel space driver.
>> The first step is a conventional smbus send byte command. Follow this
>> with a suitable delay. The second will need to make use of
>> i2c_transfer with a msg looking something like
>>
>> char bob[6];
>> struct i2c_msg read_msg = {
>> .addr = 0x19,
>> .flags = I2C_M_RD,
>> .len = 6, // as appropriate to the command
>> .buf = bob,
>> };
>>
>> then i2c_transfer(adap, &read_msg, 1);
>>
>> should do the job.
>
> Note: this could be done from userspace too if needed. The i2c-dev
> interface supports raw reads and writes.
>
Good point, I'd missed that functionality (did seem a little odd
that I couldn't find it!)
Method's much the same, but involves using the relevant ioctl
(I2C_RDWR), in conjunction iwth an appropriately filled
i2c_rdwr_ioctl_data structure.
The i2c_smbus_access function in i2c-dev.h (lm-sensors version)
is similar enough to show how to do it.
Jonathan
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