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Date: Sat, 29 Nov 2014 01:15:57 +0100 From: Stefan Agner <stefan@...er.ch> To: Arnd Bergmann <arnd@...db.de> Cc: linux-arm-kernel@...ts.infradead.org, shawn.guo@...aro.org, kernel@...gutronix.de, linux@...ck-us.net, linux-kernel@...r.kernel.org Subject: Re: [PATCH 2/2] ARM: imx: src: support vf610 system reset controller On 2014-11-28 23:22, Arnd Bergmann wrote: > On Friday 28 November 2014 23:09:09 Stefan Agner wrote: >> On 2014-11-28 22:24, Arnd Bergmann wrote: >> > On Friday 28 November 2014 22:02:01 Stefan Agner wrote: >> > >> >> > If the SRC is also capable of resetting individual blocks instead of just >> >> > the entire machine, it would be a reset driver in drivers/reset instead. >> >> >> >> Beside the system reset, there is only a mask functionality for the >> >> watchdogs (there are two watchdogs, one for Cortex-A5 and one for the >> >> M4). This makes the SRC module in the Vybrid a bit different then what >> >> is available on other i.MX SoC's... >> > >> > If you already have the watchdog registers in there and want to have >> > a watchdog driver too, the easiest way would be to register the reboot >> > handler from the watchdog driver. >> >> Hm, not sure we speak about the same here. The SRC module has two >> (multi-)bit fields to mask the watchdog reset event for each watchdog. >> Beside that, there are two full watchdog register maps, which are in >> different areas. There is already a driver for this watchdogs. I'm not >> sure what the idea behind this is exactly, I guess it would easily allow >> to (temporary) mask the other CPU's watchdog. However, I don't think we >> need that functionality, so I don't care about that right now. > > Ok, I see, thanks for the clarification! > >> There is also a restart handler in the watchdog driver, but I prefer to >> use the reset capabilities of the SRC since it has immediate effect. >> >> Lets get to the big picture again: I could register the whole SRC >> register map as a syscon device and then access the registers from my >> suspend/resume implementation later on. And similar in the restart >> driver, I would use syscon_regmap_lookup_by_compatible to check if it >> contains the vf610-src compatible string and register the restart >> driver/handler if available. One thing which came into my mind regarding suspend: I might need to access the registers from assembler (in SRAM), can I do that through syscon/regmap? I had a quick look, but I don't found a way to get back the mapped IO base address.. By good reasons, of course, for most applications. But in my case, afaik I have no other choice. -- Stefan > > Correct, and also in the watchdog driver, I guess. > > Instead of syscon_regmap_lookup_by_compatible, please use > syscon_regmap_lookup_by_phandle and put the link to the syscon > device into the device accessing it. > > Also, see if you can use or extend drivers/power/reset/syscon-reboot.c > for your use case. > > Arnd -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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