Russell, * Dave Gerlach <d-gerlach@xxxxxx> [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@xxxxxx> > --- > 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 -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
