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Commit c6e126de authored by Pawel Moll's avatar Pawel Moll
Browse files

of: Keep track of populated platform devices 



In "Device Tree powered" systems, platform devices are usually massively
populated with of_platform_populate() call, executed at some level of
initcalls, either by generic architecture or by platform-specific code.

There are situations though where certain devices must be created (and
bound with drivers) before all the others. This presents a challenge,
as devices created explicitly would be created again by
of_platform_populate().

This patch tries to solve that issue in a generic way, adding a
"populated" flag for a DT node description. Subsequent
of_platform_populate() will skip such nodes (and its children) in
a similar way to the non-available ones.

This patch also adds of_platform_depopulate() as an operation
complementary to the _populate() one. It removes a platform or an amba
device populated from the Device Tree, together with its all children
(leaving, however, devices without associated of_node untouched)
clearing the "populated" flag on the way.

Signed-off-by: default avatarPawel Moll <pawel.moll@arm.com>
Reviewed-by: default avatarRob Herring <robh@kernel.org>
Acked-by: default avatarGrant Likely <grant.likely@linaro.org>
parent d6d211db

drivers/of/platform.c

+69 −5
Original line number Diff line number Diff line
@@ -206,12 +206,13 @@ static struct platform_device *of_platform_device_create_pdata( 
{

	struct platform_device *dev;



	if (!of_device_is_available(np))

	if (!of_device_is_available(np) ||

	    of_node_test_and_set_flag(np, OF_POPULATED))

		return NULL;



	dev = of_device_alloc(np, bus_id, parent);

	if (!dev)

		return NULL;

		goto err_clear_flag;



#if defined(CONFIG_MICROBLAZE)

	dev->archdata.dma_mask = 0xffffffffUL;
@@ -229,10 +230,14 @@ static struct platform_device *of_platform_device_create_pdata( 


	if (of_device_add(dev) != 0) {

		platform_device_put(dev);

		return NULL;

		goto err_clear_flag;

	}



	return dev;



err_clear_flag:

	of_node_clear_flag(np, OF_POPULATED);

	return NULL;

}



/**
@@ -264,14 +269,15 @@ static struct amba_device *of_amba_device_create(struct device_node *node, 


	pr_debug("Creating amba device %s\n", node->full_name);



	if (!of_device_is_available(node))

	if (!of_device_is_available(node) ||

	    of_node_test_and_set_flag(node, OF_POPULATED))

		return NULL;



	dev = amba_device_alloc(NULL, 0, 0);

	if (!dev) {

		pr_err("%s(): amba_device_alloc() failed for %s\n",

		       __func__, node->full_name);

		return NULL;

		goto err_clear_flag;

	}



	/* setup generic device info */
@@ -311,6 +317,8 @@ static struct amba_device *of_amba_device_create(struct device_node *node, 


err_free:

	amba_device_put(dev);

err_clear_flag:

	of_node_clear_flag(node, OF_POPULATED);

	return NULL;

}

#else /* CONFIG_ARM_AMBA */
@@ -487,4 +495,60 @@ int of_platform_populate(struct device_node *root, 
	return rc;

}

EXPORT_SYMBOL_GPL(of_platform_populate);



static int of_platform_device_destroy(struct device *dev, void *data)

{

	bool *children_left = data;



	/* Do not touch devices not populated from the device tree */

	if (!dev->of_node || !of_node_check_flag(dev->of_node, OF_POPULATED)) {

		*children_left = true;

		return 0;

	}



	/* Recurse, but don't touch this device if it has any children left */

	if (of_platform_depopulate(dev) != 0) {

		*children_left = true;

		return 0;

	}



	if (dev->bus == &platform_bus_type)

		platform_device_unregister(to_platform_device(dev));

#ifdef CONFIG_ARM_AMBA

	else if (dev->bus == &amba_bustype)

		amba_device_unregister(to_amba_device(dev));

#endif

	else {

		*children_left = true;

		return 0;

	}



	of_node_clear_flag(dev->of_node, OF_POPULATED);



	return 0;

}



/**

 * of_platform_depopulate() - Remove devices populated from device tree

 * @parent: device which childred will be removed

 *

 * Complementary to of_platform_populate(), this function removes children

 * of the given device (and, recurrently, their children) that have been

 * created from their respective device tree nodes (and only those,

 * leaving others - eg. manually created - unharmed).

 *

 * Returns 0 when all children devices have been removed or

 * -EBUSY when some children remained.

 */

int of_platform_depopulate(struct device *parent)

{

	bool children_left = false;



	device_for_each_child(parent, &children_left,

			      of_platform_device_destroy);



	return children_left ? -EBUSY : 0;

}

EXPORT_SYMBOL_GPL(of_platform_depopulate);



#endif /* CONFIG_OF_ADDRESS */

include/linux/of.h

+7 −0
Original line number Diff line number Diff line
@@ -130,6 +130,12 @@ static inline int of_node_check_flag(struct device_node *n, unsigned long flag) 
	return test_bit(flag, &n->_flags);

}



static inline int of_node_test_and_set_flag(struct device_node *n,

					    unsigned long flag)

{

	return test_and_set_bit(flag, &n->_flags);

}



static inline void of_node_set_flag(struct device_node *n, unsigned long flag)

{

	set_bit(flag, &n->_flags);
@@ -197,6 +203,7 @@ static inline unsigned long of_read_ulong(const __be32 *cell, int size) 
/* flag descriptions */

#define OF_DYNAMIC	1 /* node and properties were allocated via kmalloc */

#define OF_DETACHED	2 /* node has been detached from the device tree */

#define OF_POPULATED	3 /* device already created for the node */



#define OF_IS_DYNAMIC(x) test_bit(OF_DYNAMIC, &x->_flags)

#define OF_MARK_DYNAMIC(x) set_bit(OF_DYNAMIC, &x->_flags)

include/linux/of_platform.h

+5 −0
Original line number Diff line number Diff line
@@ -72,6 +72,7 @@ extern int of_platform_populate(struct device_node *root, 
				const struct of_device_id *matches,

				const struct of_dev_auxdata *lookup,

				struct device *parent);

extern int of_platform_depopulate(struct device *parent);

#else

static inline int of_platform_populate(struct device_node *root,

					const struct of_device_id *matches,
@@ -80,6 +81,10 @@ static inline int of_platform_populate(struct device_node *root, 
{

	return -ENODEV;

}

static inline int of_platform_depopulate(struct device *parent)

{

	return -ENODEV;

}

#endif



#endif	/* _LINUX_OF_PLATFORM_H */