Ok, I will implement 'compatible' in the usual way.
I checked freescale i.MX21 BSP code, and found that i.MX21 KPP
registers should be compatible with those of later presented SoCs.

2012/12/31 Shawn Guo [off-list ref]:

On Sun, Dec 30, 2012 at 09:09:04PM +0800, Liu Ying wrote:

quoted

+Required SoC Specific Properties:
+- compatible: Should be "fsl,imx-kpp".

We generally use SoC name to specify the version of hardware block in
device tree binding.  In this case, the compatible string should look
like "fsl,<soc>-kpp" where <soc> is the first IMX chip using this
block.

For example, if i.MX21 is the first chip integrating the block, and
i.MX51 just integrates the same block which is completely compatible
to the one on i.MX21 for software, it should be something like below.

static struct of_device_id imx_keypad_of_match[] = {
        { .compatible = "fsl,imx21-kpp", },
        { /* sentinel */ }
};
MODULE_DEVICE_TABLE(of, imx_keypad_of_match);

kpp: kpp@73f94000 {
        compatible = "fsl,imx51-kpp", "fsl,imx21-kpp";
        ...
};

Shawn

Thanks.


-- 
Liu Ying