* Dave Gerlach <d-gerlach@xxxxxx> [171013 14:00]: > 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 processing > emif-asm-offsets.c into assembly code and then extracting the relevant > data as is done for the generated platform asm-offsets.h files. > > Signed-off-by: Dave Gerlach <d-gerlach@xxxxxx> > --- > v4->v5: > * Simplify Makefile to generate include/generated/ti-emif-asm-offsets.h Looks good to me: Acked-by: Tony Lindgren <tony@xxxxxxxxxxx> -- 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
