Subject: Re: [PATCH] cpm: Describe multi-user ram in its own device node.

From: Timur Tabi <[email-masked]>
Date: Tue, 02 Oct 2007 09:49:22 -0500

Kumar Gala wrote:
> 
> On Oct 1, 2007, at 11:10 AM, Scott Wood wrote:
> 
>> Kumar Gala wrote:
>>> On Sep 29, 2007, at 1:49 AM, Vitaly Bordug wrote:
>>>> cpms have dpram, qe has muram. these two are the same stuff in fact. 
>>>> Or you are asking about have QE stuff utilize such a binding at the 
>>>> same pass?
>>> I was asking about both these things.
>>
>> As stated in the commit message, QE can use this; it just needs a 
>> compatible entry in the data node.
> 
> can some one look at that.

Scott's proposal says this:

muram@0 {
	#address-cells = <1>;
	#size-cells = <1>;
	ranges = <0 0 10000>;

	data@0 {
		compatible = "fsl,cpm-muram-data";
		reg = <0 2000 9800 800>;
	};

Currently, the QE has this:

muram@10000 {
	device_type = "muram";
	ranges = <0 00010000 0000c000>;

	data-only@0{
		reg = <0 c000>;
	};
};

The code to process this node is qe_muram_init() in 
arch/powerpc/sysdev/qe_lib/qe.c.

	if ((np = of_find_node_by_name(NULL, "data-only")) != NULL) {
		address = *of_get_address(np, 0, &size, &flags);
		of_node_put(np);
		rh_attach_region(&qe_muram_info,
			(void *)address, (int)size);
	}

I think it would be trivial to modify this code to look for a Scott-style 
muram node.  Heck, it could be modified to look for both, and so we'll 
maintain compatibility.

-- 
Timur Tabi
Linux Kernel Developer @ Freescale