Re: new alsa driver for ti omap chip

[Takashi Iwai <tiwai@suse.de>]

At Thu, 12 Feb 2004 12:56:04 +0530,
Gupta, Kshitij wrote:
> 
> hi,
> 
> 	I am trying to write an alsa driver for a tsc2101 codec on a arm
> based SOC.  The control interface between the SOC and the tsc2101 codec is
> via SPI. 
> And the data interface is a I2S interface.  Can some one suggest a good
> starting point to start such a driver.  

some ALSA drivers use their own i2c functions, although there is a
generic i2c layer on linux kernel.  for example, delta.c or ews.c of
ice1712 driver use i2c (SPI) transfer (which calls ak4xxx-adda.c).
but it's rather complex to refer...

the i2c transfer is really easy to implement.  do just like the spec
says.  a pseudo code is like below.

	chip_select_low();
	udelay(1);

	for (i = 15; i >= 0; i--) {
		set_bit_clock(0);
		udelay(1);
		if (value_to_send & (1 << i))
			set_bit_data(1);
		else
			set_bit_data(0);
		udelay(1);
		set_bit_clock(0);
		udelay(1);
	}

	chip_select_high();


> does sound/drivers/dummy.c makes sense for such a driver ???

the dummy driver is irrelevant to the BUS type, so it makes some sense
to read the code :)


Takashi


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