On Mon, 03 Nov 2014 16:06:03 +0100
, Arnd Bergmann [off-list ref]
 wrote:

On Friday 31 October 2014 23:53:28 Rafael J. Wysocki wrote:

quoted

On Saturday, November 01, 2014 05:13:45 AM Rob Herring wrote:

quoted

On Fri, Oct 31, 2014 at 6:59 AM, Gilad Avidov [off-list ref] wrote:

quoted

Device-Tree compact API
------------------------

Common code seen in driver’s probe reads device tree values and handling
erroneous return codes from all those of_property_read_xxx()  APIs. This
common code is factored out by the of_property_map module which allows
driver’s probe to replace that (often lengthy) code with a concise table:

struct of_prop_map map[] = {
    {"i2c",            &dev->id,        OF_REQ,  OF_ID,  -1},
    {"qcom,clk-freq-out",    &dev->clk_freq_out,    OF_REQ,  OF_U32,  0},
    {"qcom,clk-freq-in",    &dev->clk_freq_in,    OF_REQ,  OF_U32,  0},
    {"qcom,disable-dma",    &dev->disable_dma,    OF_OPT,  OF_BOOL, 0},
    {"qcom,master-id",    &dev->mstr_id,        OF_SGST, OF_U32,  0},
    {NULL,            NULL,            0,       0,       0},
};

Then call populate to read the values into the device’s variables:

ret = of_prop_populate(dev, dev->of_node, map);

Interesting idea. The main concern I have with this is there has been
on-going discussions about how to generalize property handling across
DT and ACPI to make drivers more agnostic, so I'm copying a few folks
involved in that. That may be a bit orthogonal to what this is doing,
but we may want some coordination here.

Agreed.

We actually have a patchset adding a unified device property API in 
linux-next (http://git.kernel.org/cgit/linux/kernel/git/rafael/linux-pm.git/log/?h=device-properties)
and I'd prefer to see the "compactization" to happen at that level, if possible,
rather that for of_ only.

Agreed, this should definitely use the new generalized API.
I have prototyped a similar concept last year, which actually went much
further and also abstracted high-level properties such as interrupts,
gpios, pwm, dma-engine, etc. I still think we should do something
like that, but I've never had the time to follow up and nobody else
picked up my work from back then.

Would others like to see that?

Absolutely. I also tried to do the same thing and didn't get very far.
And, yes, it should be done at the level of the device properties API.

g.