On Tue, Dec 23, 2014 at 10:34 AM, Thor Thayer
<tthayer@xxxxxxxxxxxxxxxxxxxxx> wrote:
> Hi,
>
> What is the best way to queue devicetree child nodes so the node is passed
> in the platform_device pointer to the probe() function?
>
> Documentation/devicetree/usage-model.txt has the following:
>
> "For Linux DT support, the generic behaviour is for child devices to be
> registered by the parent's device driver at driver .probe() time."
>
> "Actually, it turns out that registering children of some platform_devices
> as more platform_devices is a common pattern, and the
> device tree support code reflects that and makes the above example
> simpler. The second argument to of_platform_populate() is an
> of_device_id table, and any node that matches an entry in that table
> will also get its child nodes registered."
>
>
> I tried calling of_platform_populate() in the probe of the a10_sysctl node
> but it doesn't appear to setup the platform device data properly for the
> sub-child nodes.
>
> The top child node (a10_sysctl) is probed properly and has a valid of_node
> passed in. However, the sub-child nodes such as gpio4 have null passed in
> for pdev->dev.of_node (gpio4 probe prototype is int
> a10sycon_gpio_probe(struct platform_device *pdev).
>
> My current solution is to call of_find_matching_node() in
> a10sycon_gpio_probe() to get a valid node pointer but other examples tend to
> dereference pdev->dev.of_node.
>
> Thank you in advance for your insight.
This should work. There are quite a few users already including unit
tests. Can you tell what you are doing differently from those users?
Rob
>
> Thor
>
>
> My device tree looks like this:
>
> / {
> soc {
> spi0: spi@fff00000 {
> compatible = "snps,dw-spi-mmio";
> #address-cells = <1>;
> #size-cells = <0>;
> reg = <0xfff00000 0x1000>;
> interrupts = <0 154 4>;
> num-chipselect = <4>;
> clocks = <&per_base_clk>;
> status = "okay";
>
> a10_sysctl: a10_sysctl@0 {
> compatible = "altr,a10sycon";
> reg = <0>;
> interrupt-parent = <&gpio2>;
> /* low-level active IRQ at GPIO2_24 */
> interrupts = <24 0x8>;
> interrupt-controller;
> #interrupt-cells = <2>;
> spi-max-frequency = <100000>;
>
> gpio4: gpio-controller {
> compatible = "altr,a10sycon-gpio";
> gpio-controller;
> #gpio-cells = <2>;
> ngpios = <16>;
> };
>
> a10rst: a10rst {
> compatible = "altr,a10sycon-reset";
> #reset-cells = <1>;
> };
> };
> };
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