linux-kernel - Re: [RFCv2 3/3] ARM: dts: N900: Add SSI information

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Message-ID: <20131121022125.GA2445@earth.universe>
Date:	Thu, 21 Nov 2013 03:21:27 +0100
From:	Sebastian Reichel <sre@...ian.org>
To:	Tony Lindgren <tony@...mide.com>
Cc:	Linus Walleij <linus.walleij@...aro.org>,
	Shubhrajyoti Datta <omaplinuxkernel@...il.com>,
	Carlos Chinea <cch.devel@...il.com>,
	Paul Walmsley <paul@...an.com>,
	Kevin Hilman <khilman@...prootsystems.com>,
	Russell King <linux@....linux.org.uk>,
	Grant Likely <grant.likely@...aro.org>,
	Rob Herring <rob.herring@...xeda.com>,
	Pawel Moll <pawel.moll@....com>,
	Mark Rutland <mark.rutland@....com>,
	Stephen Warren <swarren@...dotorg.org>,
	Ian Campbell <ijc+devicetree@...lion.org.uk>,
	Rob Landley <rob@...dley.net>,
	"'Benoît Cousson'" <bcousson@...libre.com>,
	devicetree@...r.kernel.org, linux-doc@...r.kernel.org,
	linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
	linux-omap@...r.kernel.org
Subject: Re: [RFCv2 3/3] ARM: dts: N900: Add SSI information

Hi Tony,

On Wed, Nov 20, 2013 at 05:38:59PM -0800, Tony Lindgren wrote:
> * Sebastian Reichel <sre@...ian.org> [130915 13:56]:
> > +
> > +Example for Nokia N900:
> > +
> > +ssi-controller@...58000 {
> > +	compatible = "ti,omap3-ssi";
> > +	ti,hwmods = "ssi";
> > +
> > +	reg = <0x48058000 0x1000>,
> > +	      <0x48059000 0x1000>;
> > +	reg-names = "sys",
> > +		    "gdd";
> > +
> > +	interrupts = <55>;
> > +	interrupt-names = "gdd_mpu";
> > +
> > +	#address-cells = <1>;
> > +	#size-cells = <1>;
> > +	ranges;
> > +
> > +	ssi-port@0 {
> > +		compatible = "ti,omap3-ssi-port";
> > +
> > +		reg = <0x4805a000 0x800>,
> > +		      <0x4805a800 0x800>;
> > +		reg-names = "tx",
> > +			    "rx";
> > +
> > +		interrupt-parent = <&intc>;
> > +		interrupts = <51>,
> > +			     <52>;
> > +		interrupt-names = "mpu_irq0",
> > +				  "mpu_irq1";
> > +
> > +		ti,ssi-cawake-gpio = <&gpio5 23 GPIO_ACTIVE_HIGH>; /* 151 */
> > +	}
> > +}
> 
> These should be in the omap3.dtsi file and not nested but separate. I'm almost
> certain that these are completely independent hardware modules and this
> means they can live their own PM life independently.
>
> So can you please do a minimal patch for omap3.dtsi that just sets up
> the standard resources separately for both modules the same way we have
> for other hardware modules in omap3.dtsi do?
> 
> One of them should be called ssi, no idea what the other module name should
> be as those register ranges show up as reserved in the docs I have.

In the public documentation of the omaps all SSI related stuff is
missing and memory areas are marked as reserved. I could not find
out how to receive the NDA version, so the following is purely
speculation based on the code.

If I understand it right the HW looks like this:

+-----------------+
|    GDD (DMA)    | <- this one is currently called ssi-controller
+--------+--------+
| Port 1 | Port 2 | <- these are currently called ssi-port
+--------+--------+

I think the GDD part must be enabled while Port 1 or Port 2 is
enabled. The last RFC driver from Carlos did not even split up the
irq/memory areas into different platform devices, but just requested
all of them in one ssi platform device.

> The other binding pieces can be added later on as they get are ready.

Sure. They are almost finished btw. I was able to get a gsm network
scan.

-- Sebastian

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