Platform data from devicetree

Quick question regarding platform_devices created from devicetree.

At the moment, we do a of_match_device() against vt8500_gpio_dt_ids[] to get an of_device_id that contains the .data field to pass into the driver.

Given that pdev is created from a match against vt8500_gpio_dt_ids[] as well, why does pdev->dev.of_node.data == NULL? Is this data not populated into this field? What data can be passed into this field?

Regards

Tony Prisk

Example code below:

static struct of_device_id vt8500_gpio_dt_ids[] = {
	{ .compatible = "via,vt8500-gpio", .data = &vt8500_data, },
	{ .compatible = "wm,wm8505-gpio", .data = &wm8505_data, },
	{ .compatible = "wm,wm8650-gpio", .data = &wm8650_data, },
	{ /* Sentinel */ },
};

static int __devinit vt8500_gpio_probe(struct platform_device *pdev)

{
	void __iomem *gpio_base;
	struct device_node *np;
	const struct of_device_id *of_id =
			of_match_device(vt8500_gpio_dt_ids, &pdev->dev);

	if (!of_id) {
		dev_err(&pdev->dev, "Failed to find gpio controller\n");
		return -ENODEV;
	}

	np = pdev->dev.of_node;
	...
}

static struct platform_driver vt8500_gpio_driver = {
	.probe		= vt8500_gpio_probe,
	.driver		= {
		.name	= "vt8500-gpio",
		.owner	= THIS_MODULE,
		.of_match_table = vt8500_gpio_dt_ids,
	},
};

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Quoted 10 lines · Tony Prisk

Quick question regarding platform_devices created from devicetree.

At the moment, we do a of_match_device() against vt8500_gpio_dt_ids[] to get an of_device_id that contains the .data field to pass into the driver.

Given that pdev is created from a match against vt8500_gpio_dt_ids[] as well, why does pdev->dev.of_node.data == NULL? Is this data not populated into this field? What data can be passed into this field?

This commit may be why:

commit b1608d69cb804e414d0887140ba08a9398e4e638

Author: Grant Likely <[email protected]>
Date:   Wed May 18 11:19:24 2011 -0600

drivercore: revert addition of of_match to struct device

Commit b826291c, "drivercore/dt: add a match table pointer to struct device" added an of_match pointer to struct device to cache the of_match_table entry discovered at driver match time. This was unsafe because matching is not an atomic operation with probing a driver. If two or more drivers are attempted to be matched to a driver at the same time, then the cached matching entry pointer could get overwritten.

This patch reverts the of_match cache pointer and reworks all users to call of_match_device() directly instead.

Signed-off-by Grant Likely <[email protected]>

Quoted 45 lines

Regards

Tony Prisk

Example code below:

static struct of_device_id vt8500_gpio_dt_ids[] = {
	{ .compatible = "via,vt8500-gpio", .data = &vt8500_data, },
	{ .compatible = "wm,wm8505-gpio", .data = &wm8505_data, },
	{ .compatible = "wm,wm8650-gpio", .data = &wm8650_data, },
	{ /* Sentinel */ },
};

static int __devinit vt8500_gpio_probe(struct platform_device *pdev)

{
	void __iomem *gpio_base;
	struct device_node *np;
	const struct of_device_id *of_id =
			of_match_device(vt8500_gpio_dt_ids, &pdev->dev);

	if (!of_id) {
		dev_err(&pdev->dev, "Failed to find gpio controller\n");
		return -ENODEV;
	}

	np = pdev->dev.of_node;
	...
}

static struct platform_driver vt8500_gpio_driver = {
	.probe		= vt8500_gpio_probe,
	.driver		= {
		.name	= "vt8500-gpio",
		.owner	= THIS_MODULE,
		.of_match_table = vt8500_gpio_dt_ids,
	},
};

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