[PATCH v2 1/2] Actions: OWL: Calculate SDRAM size

Manivannan Sadhasivam
2020-05-09T07:00:51Z

Hi Amit,

On Fri, May 08, 2020 at 03:53:45PM +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>
> ---
> Changes since v1:
> * added support for S900
> * updated the commit message to reflect common OWL
> support.
> ---
> arch/arm/mach-owl/soc.c | 27 ++++++++++++++++++++++++++-
> 1 file changed, 26 insertions(+), 1 deletion(-)
>
> diff --git a/arch/arm/mach-owl/soc.c b/arch/arm/mach-owl/soc.c
> index 409cbd319f20..2ae357e3672a 100644
> --- a/arch/arm/mach-owl/soc.c
> +++ b/arch/arm/mach-owl/soc.c
> @@ -13,15 +13,40 @@
> #include <asm/mach-types.h>
> #include <asm/psci.h>
>
> +#define DMM_INTERLEAVE_BASE (0xe0290020)
> +#define DMM_INTERLEAVE_PER_CH_CFG (DMM_INTERLEAVE_BASE + 0x08)
> +#define DMM_MASTER_READ_TO (DMM_INTERLEAVE_BASE + 0x48)
> +
> DECLARE_GLOBAL_DATA_PTR;
>
> +unsigned int get_owl_ram_size(void)
> +{
> + __maybe_unused unsigned int val, cap, channel, channel_num;
> +
> + /* 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)
> + chennel_num = (readl(DMM_INTERLEAVE_BASE) >> 24) & 0xf;
> + channel = (ch_num >= 3) ? 1 : 0;
> + val = (readl(DMM_MASTER_READ_TO)) & 0xf;
> + cap = ((val + 1) << channel) * 256;

This doesn't work on Bubblegum96. But poking into the vendor tree, I'm able
to come up with below working code:

val = (readl(DMM_INTERLEAVE_PER_CH_CFG) >> 8) & 0xf;
cap = 64 * (1 << val);

So, you can use this and remove other stuffs. Also this function should be named
as owl_get_ddr_cap().

Thanks,
Mani

> +#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 = get_owl_ram_size() * 1024 * 1024;
> return 0;
> +
> }
>
> /* This is called after dram_init() so use get_ram_size result */
> --
> 2.7.4
>