[U-Boot] [PATCH] DW SPI: Allow to overload the management of the external CS

[Daniel Schwierzeck]

On 25.09.2018 15:17, Gregory CLEMENT wrote:
> On some platforms, as the Ocelot ones, when wanting to control the CS
> through software, it is not possible to do it through the GPIO
> controller. Indeed, this signal is managed through a dedicated range of
> registers inside the SoC..

and why did you add a spi-bitbang-gpio driver?

> 
> By declaring the external_cs_manage function as weak, it is possible to
> manage the CS at platform level and then using the appropriate registers.
> 
> Signed-off-by: Gregory CLEMENT <gregory.clement at bootlin.com>
> ---
>  drivers/spi/designware_spi.c | 8 +++++++-
>  1 file changed, 7 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/spi/designware_spi.c b/drivers/spi/designware_spi.c
> index d8b73ea326..fe6e753bff 100644
> --- a/drivers/spi/designware_spi.c
> +++ b/drivers/spi/designware_spi.c
> @@ -334,7 +334,13 @@ static int poll_transfer(struct dw_spi_priv *priv)
>  	return 0;
>  }
>  
> -static void external_cs_manage(struct udevice *dev, bool on)
> +/*
> + * We define external_cs_manage function as 'weak' as some targets
> + * (like OCELOT) don't control the external CS pin using a GPIO
> + * controller. These SoCs use specific registers to controll by
> + * software the SPI pins (and especially the CS).
> + */
> +__weak void external_cs_manage(struct udevice *dev, bool on)
>  {
>  #if defined(CONFIG_DM_GPIO) && !defined(CONFIG_SPL_BUILD)
>  	struct dw_spi_priv *priv = dev_get_priv(dev->parent);
> 

-- 
- Daniel

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