On 7/24/2017 2:24 PM, Dave Gerlach wrote:
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> --- v2->v3: * Move all static vars into common struct and instead point to one static instance of this struct and pass this struct around for internal calls. * Rename ti_emif_prepare_push_sram to ti_emif_alloc_sram * Clean up probe path to avoid leftover vairable values from being used after probe defer or failure. * Fix mistake in ASM code that stored EMIF_POWER_MANAGEMENT_CONTROL into location for shadow register. * Avoid extern definition for asm-offsets definition and use a stub instead of defining out in asm-offsets. * A few general fixups to code. arch/arm/kernel/asm-offsets.c | 4 + drivers/memory/Kconfig | 10 ++ drivers/memory/Makefile | 4 + drivers/memory/emif.h | 17 ++ drivers/memory/ti-emif-pm.c | 339 +++++++++++++++++++++++++++++++++++++++ drivers/memory/ti-emif-sram-pm.S | 334 ++++++++++++++++++++++++++++++++++++++ include/linux/ti-emif-sram.h | 147 +++++++++++++++++ 7 files changed, 855 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
I will need RMKs blessing since he reviewed the ASM code. Also need work out how to line this up. Typically I use to get driver/memory patches via Greg's driver-core but this is more PM code than memory driver and very SOC specific. Hi Arnd/Olof, Will you be ok to pull this via arm-soc ? There is also follow up platform PM code and DTS series which will make use of this. Regards, Santosh -- 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
