[PATCH v4 1/2] Actions: OWL: Calculate SDRAM size

[Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>]

On Sat, May 09, 2020 at 01:45:07PM +0530, Amit Singh Tomar wrote:
> Calculate the SDRAM size from DDR capacity register registers instead
> of using hard-coded value. This is quite useful to get correct size
> on differnt boards based on Actions OWL family of SoCs (S700 and S900).
> 
> There is no documentation available that talks about DDR registers, and
> this is very much taken from vendor source.
> 
> This commit lets Linux boot on Cubieboard7-lite(based on S700).
> 
> Signed-off-by: Amit Singh Tomar <amittomer25@gmail.com>

Reviewed-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>

Thanks,
Mani

> ---
> Changes since v3:
> 	* Fixed S900 support as suggested by Mani.
> 	* Changes the function name to owl_get_ddrcap.
> Changes since v2:
> 	* Fixed the variable name so that it can compile
> 	  for S900.	
> Changes since v1:
>         * added support for S900
>         * updated the commit message to reflect common OWL
>           support.
> ---
>  arch/arm/mach-owl/soc.c | 22 +++++++++++++++++++++-
>  1 file changed, 21 insertions(+), 1 deletion(-)
> 
> diff --git a/arch/arm/mach-owl/soc.c b/arch/arm/mach-owl/soc.c
> index 409cbd319f20..fcf61d39b63a 100644
> --- a/arch/arm/mach-owl/soc.c
> +++ b/arch/arm/mach-owl/soc.c
> @@ -13,14 +13,34 @@
>  #include <asm/mach-types.h>
>  #include <asm/psci.h>
>  
> +#define DMM_INTERLEAVE_PER_CH_CFG	0xe0290028
> +
>  DECLARE_GLOBAL_DATA_PTR;
>  
> +unsigned int owl_get_ddrcap(void)
> +{
> +	unsigned int val, cap;
> +
> +	/* ddr capacity register initialized by ddr driver
> +	 * in early bootloader
> +	 */
> +#if defined(CONFIG_MACH_S700)
> +	val = (readl(DMM_INTERLEAVE_PER_CH_CFG) >> 8) & 0x7;
> +	cap =  (val + 1) * 256;
> +#elif defined(CONFIG_MACH_S900)
> +	val = (readl(DMM_INTERLEAVE_PER_CH_CFG) >> 8) & 0xf;
> +	cap =  64 * (1 << val);
> +#endif
> +
> +	return cap;
> +}
> +
>  /*
>   * dram_init - sets uboots idea of sdram size
>   */
>  int dram_init(void)
>  {
> -	gd->ram_size = CONFIG_SYS_SDRAM_SIZE;
> +	gd->ram_size = owl_get_ddrcap() * 1024 * 1024;
>  	return 0;
>  }
>  
> -- 
> 2.7.4
>