Re: [lm-sensors] HMC6343

[Jean Delvare <khali-PUYAD+kWke1g9hUCZPvPmw@public.gmane.org>]

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.

-- 
Jean Delvare