On Thu, 12 Feb 2004, Takashi Iwai wrote:
> 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();
Note that I2S is not I2C. I2S is used to connect A/D and D/A converters
(three wires - clock, l/r word and sample bit). We don't talk directly
with any device over this serial bus.
I think that the driver must be written for a sound bridge between host
and the converters. In case of ARM platform, it's usually an integrated
serial controller which can do DMA transfers.
So, this I2S question is a bit irrelevant (it's for hardware designers,
but not for driver developers).
Because I don't know the behaviour of the sound / serial bridge, I cannot
suggest a driver, but if it's similar as ARM1100 architecture, then we
have already a driver for it.
Jaroslav
-----
Jaroslav Kysela <[EMAIL PROTECTED]>
Linux Kernel Sound Maintainer
ALSA Project, SuSE Labs
-------------------------------------------------------
SF.Net is sponsored by: Speed Start Your Linux Apps Now.
Build and deploy apps & Web services for Linux with
a free DVD software kit from IBM. Click Now!
http://ads.osdn.com/?ad_id=1356&alloc_id=3438&op=click
_______________________________________________
Alsa-devel mailing list
[EMAIL PROTECTED]
https://lists.sourceforge.net/lists/listinfo/alsa-devel
