Messages in this thread | | | Subject | Re: [PATCH v3 2/2] memory: ti-emif-sram: introduce relocatable suspend/resume handlers | From | Santosh Shilimkar <> | Date | Tue, 1 Aug 2017 11:08:19 -0700 |
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On 7/26/2017 9:54 AM, Santosh Shilimkar wrote: > > 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@ti.com> >> --- [...]
>> >> 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. > Looks like I missed to copy Olof. Let me know guys if you are ok to pull this into your driver-soc given the dependencies.
Regards Santosh
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