linux-kernel - Re: [PATCH 2/3] soc: ti: Add wkup_m3

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Message-ID: <20150226220817.GR11056@atomide.com>
Date:	Thu, 26 Feb 2015 14:08:17 -0800
From:	Tony Lindgren <tony@...mide.com>
To:	Dave Gerlach <d-gerlach@...com>
Cc:	balbi@...com, linux-arm-kernel@...ts.infradead.org,
	linux-kernel@...r.kernel.org, linux-omap@...r.kernel.org,
	devicetree@...r.kernel.org, Benoit Cousson <bcousson@...libre.com>,
	Ohad Ben-Cohen <ohad@...ery.com>, Suman Anna <s-anna@...com>,
	Arnd Bergmann <arnd@...db.de>,
	Kevin Hilman <khilman@...aro.org>
Subject: Re: [PATCH 2/3] soc: ti: Add wkup_m3_ipc driver

* Dave Gerlach <d-gerlach@...com> [150226 12:05]:
> Tony,
> On 01/05/2015 04:51 PM, Tony Lindgren wrote:
> > * Dave Gerlach <d-gerlach@...com> [150105 14:51]:
> >> Felipe,
> >> On 01/02/2015 02:16 PM, Felipe Balbi wrote:
> >>> On Fri, Jan 02, 2015 at 02:00:16PM -0600, Dave Gerlach wrote:
> >>>> Introduce a wkup_m3_ipc driver to handle communication between the MPU
> >>>> and Cortex M3 wkup_m3 present on am335x.
> >>>>
> >>>> This driver is responsible for actually booting the wkup_m3_rproc and
> >>>> also handling all IPC which is done using the IPC registers in the control
> >>>> module, a mailbox, and a separate interrupt back from the wkup_m3. A small
> >>>> API is exposed for executing specific power commands, which include
> >>>> configuring for low power mode, request a transition to a low power mode,
> >>>> and status info on a previous transition.
> >>>>
> >>>> Signed-off-by: Dave Gerlach <d-gerlach@...com>
> >>>> ---
> >>>>  drivers/soc/ti/Kconfig       |  11 ++
> >>>>  drivers/soc/ti/Makefile      |   1 +
> >>>>  drivers/soc/ti/wkup_m3_ipc.c | 451 +++++++++++++++++++++++++++++++++++++++++++
> >>>>  include/linux/wkup_m3_ipc.h  |  33 ++++
> >>>>  4 files changed, 496 insertions(+)
> >>>>  create mode 100644 drivers/soc/ti/wkup_m3_ipc.c
> >>>>  create mode 100644 include/linux/wkup_m3_ipc.h
> >>>>
> >>>> diff --git a/drivers/soc/ti/Kconfig b/drivers/soc/ti/Kconfig
> >>>> index 7266b21..61cda85 100644
> >>>> --- a/drivers/soc/ti/Kconfig
> >>>> +++ b/drivers/soc/ti/Kconfig
> >>>> @@ -28,4 +28,15 @@ config KEYSTONE_NAVIGATOR_DMA
> >>>>  
> >>>>  	  If unsure, say N.
> >>>>  
> >>>> +config WKUP_M3_IPC
> >>>> +	bool "TI AM33XX Wkup-M3 IPC Driver"
> >>>
> >>> tristate ?
> >>
> >> If we want to allow this and the rproc driver to be built as modules than we can
> >> change this.
> > 
> > Yes please, the PM is never needed early, and should be optional.
> > And doing that will make it a lot easier for you to do further work
> > on your driver ;)
> > 
> > And it will also make it easier to add support for other SoCs as
> > it seems the same M3 is used at least on am437x.
> >  
> 
> I can not build the PM code as a module at this time due to many mach-omap
> function calls it uses which are not exported, so I need handles to all five
> functions in this driver used in pm33xx to call from built-in PM code. Do you
> have a preference on how these function handles get passed?

OK, you can pass the function pointers in platform_data. Care to
list those functions? That might allow us to make other omap PM
code into loadable modules in drivers/* :)
 
> I currently have added a pdata-quirks implementation that passes a function to
> the wkup_m3_ipc driver through it's pdata which it then calls at probe to pass a
> struct containing all used function pointers to the pm code that were previously
> called directly. Is that what you would prefer or something else? I had also
> looked at making the struct of function pointers in the driver global and just
> picking it up from the pm code with an extern declaration or even putting a bus
> notifier in the PM code and watching for the wkup_m3_ipc driver to be bound.

Yeah pdata-quirks.c is probably OK for populating the function pointers.
We may have already some place in the PM code to pass it too.
 
> Thought I would see what you prefer and possibly avoid an unnecessary re-spin.

Sounds like we're getting close to getting am335x/am437x PM code working :)

Regards,

Tony
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