linux-kernel - Re: [PATCH] arm, omap2, sram: On HS/EMU devices, only 64K internal SRAM is available.

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Message-ID: <20151014174920.GE10113@atomide.com>
Date:	Wed, 14 Oct 2015 10:49:20 -0700
From:	Tony Lindgren <tony@...mide.com>
To:	Heiko Schocher <hs@...x.de>
Cc:	linux-kernel@...r.kernel.org, Ayoub Zaki <Ayoub.Zaki@...ch-si.com>,
	Russell King <linux@....linux.org.uk>,
	linux-omap@...r.kernel.org, Georg.Soffel@...ch-si.com,
	linux-arm-kernel@...ts.infradead.org
Subject: Re: [PATCH] arm, omap2, sram: On HS/EMU devices, only 64K internal
 SRAM is available.

* Heiko Schocher <hs@...x.de> [151012 22:58]:
> Of this, secure content (including PPA) uses initial
> portion of the SRAM. This chunk is not (and shouldn't
> be) accessible from the public code.
> 
> The minimum size of this chunk (0x350) is used in this
> patch. Available size is rounded off to 63K.
> 
> Both values would require a change if size of secure
> content grows beyond 0x350.

Makes sense to me. And something similar is needed at least for
dm814x to get rid of the imprecise abort during boot with
commit bbeb92095159 ("ARM: 8422/1: enable imprecise aborts during
early kernel startup") applied.

Is this needed as a fix to the -rc cycle, or can this wait for
v4.4?

Regards,

Tony


> Signed-off-by: Heiko Schocher <hs@...x.de>
> Signed-off-by: Ayoub Zaki <Ayoub.Zaki@...ch-si.com>
> ---
> 
>  arch/arm/mach-omap2/sram.c | 25 +++++++++++++++++++++++++
>  1 file changed, 25 insertions(+)
> 
> diff --git a/arch/arm/mach-omap2/sram.c b/arch/arm/mach-omap2/sram.c
> index cd488b8..2e7c00f 100644
> --- a/arch/arm/mach-omap2/sram.c
> +++ b/arch/arm/mach-omap2/sram.c
> @@ -47,6 +47,28 @@
>  
>  #define GP_DEVICE		0x300
>  
> +/**
> + * Size of chunk used by secure content in the HS/EMU devices.
> + *
> + * This size is not fixed. It depends upon the implementation of PPA.
> + * May need to be modified if the size grows.
> + */
> +#define AM33XX_HS_HEADER_SIZE   0x0350
> +
> +/**
> + * Start of public SRAM on HS/EMU devices.
> + */
> +#define AM33XX_SRAM_PA		0x40300000
> +#define AM33XX_SRAM_PUB_PA	(AM33XX_SRAM_PA + AM33XX_HS_HEADER_SIZE)
> +
> +/**
> + * Size of public SRAM available on HS/EMU devices.
> + *
> + * This size also depends upon AM33XX_HS_HEADER_SIZE.
> + * Current value is derived from nearest round-off.
> + */
> +#define AM33XX_SRAM_PUB_SIZE		0xfc00	/* 63K */
> +
>  #define ROUND_DOWN(value,boundary)	((value) & (~((boundary)-1)))
>  
>  static unsigned long omap_sram_start;
> @@ -99,6 +121,9 @@ static void __init omap_detect_sram(void)
>  			} else {
>  				omap_sram_size = 0x8000; /* 32K */
>  			}
> +		} else if (soc_is_am33xx()) {
> +			omap_sram_start = AM33XX_SRAM_PUB_PA;
> +			omap_sram_size  = AM33XX_SRAM_PUB_SIZE;
>  		} else {
>  			omap_sram_start = OMAP2_SRAM_PUB_PA;
>  			omap_sram_size = 0x800; /* 2K */
> -- 
> 2.1.0
> 
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