virtio-scmi: power domain of_genpd_add_device() called without of_node, causing crash on Rockchip PMU #107

// power_domain_init()
pdev = platform_device_alloc("hvisor-power", domain_id);
// pdev->dev.of_node == NULL  <- of_node not set
ret = of_genpd_add_device(&args, &pdev->dev);  // <- crash

static int rockchip_pd_attach_dev(struct generic_pm_domain *genpd,
                                  struct device *dev)
{
    struct clk *clk;
    int i, error;

    error = pm_clk_create(dev);
    if (error)
        return error;

    i = 0;
    // dev->of_node == NULL -> of_clk_get(NULL, i) crashes
    while ((clk = of_clk_get(dev->of_node, i++)) && !IS_ERR(clk)) {
        error = pm_clk_add_clk(dev, clk);
        if (error) {
            clk_put(clk);
            pm_clk_destroy(dev);
            return error;
        }
    }
    return 0;
}

/**
 * genpd_dev_pm_attach_by_id - Associate a device with one of its PM domains.
 * @dev: The device used to lookup the PM domain.
 * @index: The index of the PM domain.
 *
 * Parse device's OF node to find a PM domain specifier at the provided @index.
 * If such is found, creates a virtual device and attaches it to the retrieved
 * pm_domain ops.
 *
 * Returns the created virtual device if successfully attached PM domain, NULL
 * when the device don't need a PM domain, else an ERR_PTR() in case of failures.
 * If a power-domain exists for the device, but cannot be found or turned on,
 * then ERR_PTR(-EPROBE_DEFER) is returned.
 */
struct device *genpd_dev_pm_attach_by_id(struct device *dev,
					 unsigned int index)
{
	struct device *virt_dev;
	int num_domains;
	int ret;

	if (!dev->of_node)
		return NULL;

	/* Verify that the index is within a valid range. */
	num_domains = of_count_phandle_with_args(dev->of_node, "power-domains",
						 "#power-domain-cells");
	if (num_domains < 0 || index >= num_domains)
		return NULL;

	if (!genpd_bus_registered)
		return ERR_PTR(-ENODEV);

	/* Allocate and register device on the genpd bus. */
	virt_dev = kzalloc_obj(*virt_dev);
	if (!virt_dev)
		return ERR_PTR(-ENOMEM);

	dev_set_name(virt_dev, "genpd:%u:%s", index, dev_name(dev));
	virt_dev->bus = &genpd_bus_type;
	virt_dev->release = genpd_release_dev;
	virt_dev->of_node = of_node_get(dev->of_node);  // inherits of_node

	ret = device_register(virt_dev);
	if (ret) {
		put_device(virt_dev);
		return ERR_PTR(ret);
	}

	/* Attach to the PM domain at the specified index. */
	ret = __genpd_dev_pm_attach(virt_dev, dev, index, num_domains, false);
	if (ret < 1) {
		device_unregister(virt_dev);
		return ret ? ERR_PTR(ret) : NULL;
	}

	pm_runtime_enable(virt_dev);
	genpd_queue_power_off_work(dev_to_genpd(virt_dev));

	return virt_dev;  // usable directly with pm_runtime_resume_and_get()
}
EXPORT_SYMBOL_GPL(genpd_dev_pm_attach_by_id);

static int power_domain_init(u32 domain_id) {
    ...
    if (!ctrl_pdev) {
        ctrl_pdev = platform_device_alloc("hvisor-pd", -1);
        ...
        ctrl_pdev->dev.of_node = np;  // Bind to hvisor DT node
        platform_device_add(ctrl_pdev);
    }

    virt_dev = genpd_dev_pm_attach_by_id(&ctrl_pdev->dev, domain_id);
    if (IS_ERR_OR_NULL(virt_dev))
        return virt_dev ? PTR_ERR(virt_dev) : -ENODEV;

    power_devices[domain_id].virt_dev = virt_dev;
    power_devices[domain_id].attached = true;
    return 0;
}