From: Tony Lindgren <tony@atomide.com>
To: Russell King <linux@armlinux.org.uk>
Cc: Rob Herring <robh+dt@kernel.org>,
Santosh Shilimkar <ssantosh@kernel.org>,
linux-arm-kernel@lists.infradead.org, linux-omap@vger.kernel.org,
linux-kernel@vger.kernel.org, devicetree@vger.kernel.org,
Keerthy J <j-keerthy@ti.com>, Dave Gerlach <d-gerlach@ti.com>
Subject: Re: [PATCH 2/2] memory: ti-emif-sram: introduce relocatable suspend/resume handlers
Date: Tue, 4 Apr 2017 09:11:52 -0700 [thread overview]
Message-ID: <20170404161151.GS10760@atomide.com> (raw)
In-Reply-To: <20170328205511.21166-3-d-gerlach@ti.com>
Russell,
* Dave Gerlach <d-gerlach@ti.com> [170328 13:57]:
> Certain SoCs like Texas Instruments AM335x and AM437x require parts
> of the EMIF PM code to run late in the suspend sequence from SRAM,
> such as saving and restoring the EMIF context and placing the memory
> into self-refresh.
>
> One requirement for these SoCs to suspend and enter its lowest power
> mode, called DeepSleep0, is that the PER power domain must be shut off.
> Because the EMIF (DDR Controller) resides within this power domain, it
> will lose context during a suspend operation, so we must save it so we
> can restore once we resume. However, we cannot execute this code from
> external memory, as it is not available at this point, so the code must
> be executed late in the suspend path from SRAM.
>
> This patch introduces a ti-emif-sram driver that includes several
> functions written in ARM ASM that are relocatable so the PM SRAM
> code can use them. It also allocates a region of writable SRAM to
> be used by the code running in the executable region of SRAM to save
> and restore the EMIF context. It can export a table containing the
> absolute addresses of the available PM functions so that other SRAM
> code can branch to them. This code is required for suspend/resume on
> AM335x and AM437x to work.
>
> In addition to this, to be able to share data structures between C and
> the ti-emif-sram-pm assembly code, we can automatically generate all of
> the C struct member offsets and sizes as macros by making use of the ARM
> asm-offsets file. In the same header that we define our data structures
> in we also define all the macros in an inline function and by adding a
> call to this in the asm_offsets file all macros are properly generated
> and available to the assembly code without cluttering up the asm-offsets
> file.
>
> Signed-off-by: Dave Gerlach <d-gerlach@ti.com>
> ---
> arch/arm/kernel/asm-offsets.c | 6 +
> drivers/memory/Kconfig | 10 ++
> drivers/memory/Makefile | 4 +
> drivers/memory/emif.h | 17 ++
> drivers/memory/ti-emif-pm.c | 295 ++++++++++++++++++++++++++++++++++
> drivers/memory/ti-emif-sram-pm.S | 334 +++++++++++++++++++++++++++++++++++++++
> include/linux/ti-emif-sram.h | 143 +++++++++++++++++
> 7 files changed, 809 insertions(+)
> create mode 100644 drivers/memory/ti-emif-pm.c
> create mode 100644 drivers/memory/ti-emif-sram-pm.S
> create mode 100644 include/linux/ti-emif-sram.h
>
> diff --git a/arch/arm/kernel/asm-offsets.c b/arch/arm/kernel/asm-offsets.c
> index 608008229c7d..d728b5660e36 100644
> --- a/arch/arm/kernel/asm-offsets.c
> +++ b/arch/arm/kernel/asm-offsets.c
> @@ -28,6 +28,7 @@
> #include <asm/vdso_datapage.h>
> #include <asm/hardware/cache-l2x0.h>
> #include <linux/kbuild.h>
> +#include <linux/ti-emif-sram.h>
>
> /*
> * Make sure that the compiler and target are compatible.
> @@ -183,5 +184,10 @@ int main(void)
> #ifdef CONFIG_VDSO
> DEFINE(VDSO_DATA_SIZE, sizeof(union vdso_data_store));
> #endif
> +#if defined(CONFIG_SOC_AM33XX) || defined(CONFIG_SOC_AM43XX)
> + BLANK();
> + ti_emif_offsets();
> +#endif
> +
> return 0;
> }
Does the above look OK to you?
Regards,
Tony
next prev parent reply other threads:[~2017-04-04 16:12 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-03-28 20:55 [PATCH 0/2] memory: Introduce ti-emif-sram driver Dave Gerlach
2017-03-28 20:55 ` [PATCH 1/2] Documentation: dt: Update ti,emif bindings Dave Gerlach
2017-04-03 14:34 ` Rob Herring
2017-03-28 20:55 ` [PATCH 2/2] memory: ti-emif-sram: introduce relocatable suspend/resume handlers Dave Gerlach
2017-04-04 16:11 ` Tony Lindgren [this message]
2017-04-05 13:59 ` Russell King - ARM Linux
2017-04-05 14:33 ` Tony Lindgren
2017-04-05 14:48 ` Dave Gerlach
2017-04-06 19:00 ` Russell King - ARM Linux
2017-04-06 19:09 ` Dave Gerlach
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