Re: Ask for help on SPI slave side driver support

[ysh <youshenghui0322@163.com>]

On 2013-10-14 19:25, Mark Brown wrote:
> On Mon, Oct 14, 2013 at 03:05:58AM +0800, YouShenghui wrote:
>
> Please fix your mailer to word wrap within paragraphs, your messages are
> very hard to read.
>
>> Ok, I have one question when reading drivers/spi/spi-s3c64xx.c
>> In s3c64xx_spi_setup, cs->line(S3C64XX_GPC(3)) is set to GPIOF_OUT_INIT_HIGH, that means an general output pin.
>> But the other three(clk, mosi, miso) was set to 2 by s3c64xx_spi0_cfg_gpio. This is just what is needed by SPI.
>> My question is why wasn't cs->line also set to 2 to use SPI CS0?
>
> In common with many drivers this driver controls the chp select as a
> GPIO.  Generally the hardware is less flexible than Linux can be if it
> implements automatic chip select handling at all.
>
>> When I want to use spi as slave side, should I set S3C64XX_GPC(3)'s cfg of  to 0(input) or 2?
>
> I don't think the controller has any slave support natively so you'd
> probably need to put it into GPIO mode.
Got it, then what about the setting of clk, mosi, miso pin in slave mode?
Do you mean I need to simulate spi slave side using four gpios?

thanks
zduan