drivers/of/platform.c - kernel/msm-5.4 - Gitiles

 /*
  *    Copyright (C) 2006 Benjamin Herrenschmidt, IBM Corp.
  *			 <benh@kernel.crashing.org>
  *    and		 Arnd Bergmann, IBM Corp.
  *    Merged from powerpc/kernel/of_platform.c and
  *    sparc{,64}/kernel/of_device.c by Stephen Rothwell
  *
  *  This program is free software; you can redistribute it and/or
  *  modify it under the terms of the GNU General Public License
  *  as published by the Free Software Foundation; either version
  *  2 of the License, or (at your option) any later version.
  *
  */
 #include <linux/errno.h>
 #include <linux/module.h>
 #include <linux/amba/bus.h>
 #include <linux/device.h>
 #include <linux/dma-mapping.h>
 #include <linux/slab.h>
 #include <linux/of_address.h>
 #include <linux/of_device.h>
 #include <linux/of_irq.h>
 #include <linux/of_platform.h>
 #include <linux/platform_device.h>

 const struct of_device_id of_default_bus_match_table[] = {
 	{ .compatible = "simple-bus", },
 #ifdef CONFIG_ARM_AMBA
 	{ .compatible = "arm,amba-bus", },
 #endif /* CONFIG_ARM_AMBA */
 	{} /* Empty terminated list */
 };

 static int of_dev_node_match(struct device *dev, void *data)
 {
 	return dev->of_node == data;
 }

 /**
  * of_find_device_by_node - Find the platform_device associated with a node
  * @np: Pointer to device tree node
  *
  * Returns platform_device pointer, or NULL if not found
  */
 struct platform_device *of_find_device_by_node(struct device_node *np)
 {
 	struct device *dev;

 	dev = bus_find_device(&platform_bus_type, NULL, np, of_dev_node_match);
 	return dev ? to_platform_device(dev) : NULL;
 }
 EXPORT_SYMBOL(of_find_device_by_node);

 #ifdef CONFIG_OF_ADDRESS
 /*
  * The following routines scan a subtree and registers a device for
  * each applicable node.
  *
  * Note: sparc doesn't use these routines because it has a different
  * mechanism for creating devices from device tree nodes.
  */

 /**
  * of_device_make_bus_id - Use the device node data to assign a unique name
  * @dev: pointer to device structure that is linked to a device tree node
  *
  * This routine will first try using the translated bus address to
  * derive a unique name. If it cannot, then it will prepend names from
  * parent nodes until a unique name can be derived.
  */
 void of_device_make_bus_id(struct device *dev)
 {
 	struct device_node *node = dev->of_node;
 	const __be32 *reg;
 	u64 addr;

 	/* Construct the name, using parent nodes if necessary to ensure uniqueness */
 	while (node->parent) {
 		/*
 		 * If the address can be translated, then that is as much
 		 * uniqueness as we need. Make it the first component and return
 		 */
 		reg = of_get_property(node, "reg", NULL);
 		if (reg && (addr = of_translate_address(node, reg)) != OF_BAD_ADDR) {
 			dev_set_name(dev, dev_name(dev) ? "%llx.%s:%s" : "%llx.%s",
 				     (unsigned long long)addr, node->name,
 				     dev_name(dev));
 			return;
 		}

 		/* format arguments only used if dev_name() resolves to NULL */
 		dev_set_name(dev, dev_name(dev) ? "%s:%s" : "%s",
 			     strrchr(node->full_name, '/') + 1, dev_name(dev));
 		node = node->parent;
 	}
 }

 /**
  * of_device_alloc - Allocate and initialize an of_device
  * @np: device node to assign to device
  * @bus_id: Name to assign to the device.  May be null to use default name.
  * @parent: Parent device.
  */
 struct platform_device *of_device_alloc(struct device_node *np,
 				  const char *bus_id,
 				  struct device *parent)
 {
 	struct platform_device *dev;
 	int rc, i, num_reg = 0, num_irq;
 	struct resource *res, temp_res;

 	dev = platform_device_alloc("", -1);
 	if (!dev)
 		return NULL;

 	/* count the io and irq resources */
 	while (of_address_to_resource(np, num_reg, &temp_res) == 0)
 		num_reg++;
 	num_irq = of_irq_count(np);

 	/* Populate the resource table */
 	if (num_irq || num_reg) {
 		res = kzalloc(sizeof(*res) * (num_irq + num_reg), GFP_KERNEL);
 		if (!res) {
 			platform_device_put(dev);
 			return NULL;
 		}

 		dev->num_resources = num_reg + num_irq;
 		dev->resource = res;
 		for (i = 0; i < num_reg; i++, res++) {
 			rc = of_address_to_resource(np, i, res);
 			WARN_ON(rc);
 		}
 		if (of_irq_to_resource_table(np, res, num_irq) != num_irq)
 			pr_debug("not all legacy IRQ resources mapped for %s\n",
 				 np->name);
 	}

 	dev->dev.of_node = of_node_get(np);
 	dev->dev.parent = parent;

 	if (bus_id)
 		dev_set_name(&dev->dev, "%s", bus_id);
 	else
 		of_device_make_bus_id(&dev->dev);

 	return dev;
 }
 EXPORT_SYMBOL(of_device_alloc);

 /**
  * of_dma_configure - Setup DMA configuration
  * @dev:	Device to apply DMA configuration
  *
  * Try to get devices's DMA configuration from DT and update it
  * accordingly.
  *
  * In case if platform code need to use own special DMA configuration,it
  * can use Platform bus notifier and handle BUS_NOTIFY_ADD_DEVICE event
  * to fix up DMA configuration.
  */
 static void of_dma_configure(struct platform_device *pdev)
 {
 	u64 dma_addr, paddr, size;
 	int ret;
 	struct device *dev = &pdev->dev;

 	/*
 	 * Set default dma-mask to 32 bit. Drivers are expected to setup
 	 * the correct supported dma_mask.
 	 */
 	dev->coherent_dma_mask = DMA_BIT_MASK(32);

 	/*
 	 * Set it to coherent_dma_mask by default if the architecture
 	 * code has not set it.
 	 */
 	if (!dev->dma_mask)
 		dev->dma_mask = &dev->coherent_dma_mask;

 	/*
 	 * if dma-coherent property exist, call arch hook to setup
 	 * dma coherent operations.
 	 */
 	if (of_dma_is_coherent(dev->of_node)) {
 		set_arch_dma_coherent_ops(dev);
 		dev_dbg(dev, "device is dma coherent\n");
 	}

 	/*
 	 * if dma-ranges property doesn't exist - just return else
 	 * setup the dma offset
 	 */
 	ret = of_dma_get_range(dev->of_node, &dma_addr, &paddr, &size);
 	if (ret < 0) {
 		dev_dbg(dev, "no dma range information to setup\n");
 		return;
 	}

 	/* DMA ranges found. Calculate and set dma_pfn_offset */
 	dev->dma_pfn_offset = PFN_DOWN(paddr - dma_addr);
 	dev_dbg(dev, "dma_pfn_offset(%#08lx)\n", dev->dma_pfn_offset);
 }

 /**
  * of_platform_device_create_pdata - Alloc, initialize and register an of_device
  * @np: pointer to node to create device for
  * @bus_id: name to assign device
  * @platform_data: pointer to populate platform_data pointer with
  * @parent: Linux device model parent device.
  *
  * Returns pointer to created platform device, or NULL if a device was not
  * registered.  Unavailable devices will not get registered.
  */
 static struct platform_device *of_platform_device_create_pdata(
 					struct device_node *np,
 					const char *bus_id,
 					void *platform_data,
 					struct device *parent)
 {
 	struct platform_device *dev;

 	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)
 		goto err_clear_flag;

 	of_dma_configure(dev);
 	dev->dev.bus = &platform_bus_type;
 	dev->dev.platform_data = platform_data;

 	/* We do not fill the DMA ops for platform devices by default.
 	 * This is currently the responsibility of the platform code
 	 * to do such, possibly using a device notifier
 	 */

 	if (of_device_add(dev) != 0) {
 		platform_device_put(dev);
 		goto err_clear_flag;
 	}

 	return dev;

 err_clear_flag:
 	of_node_clear_flag(np, OF_POPULATED);
 	return NULL;
 }

 /**
  * of_platform_device_create - Alloc, initialize and register an of_device
  * @np: pointer to node to create device for
  * @bus_id: name to assign device
  * @parent: Linux device model parent device.
  *
  * Returns pointer to created platform device, or NULL if a device was not
  * registered.  Unavailable devices will not get registered.
  */
 struct platform_device *of_platform_device_create(struct device_node *np,
 					    const char *bus_id,
 					    struct device *parent)
 {
 	return of_platform_device_create_pdata(np, bus_id, NULL, parent);
 }
 EXPORT_SYMBOL(of_platform_device_create);

 #ifdef CONFIG_ARM_AMBA
 static struct amba_device *of_amba_device_create(struct device_node *node,
 						 const char *bus_id,
 						 void *platform_data,
 						 struct device *parent)
 {
 	struct amba_device *dev;
 	const void *prop;
 	int i, ret;

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

 	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);
 		goto err_clear_flag;
 	}

 	/* setup generic device info */
 	dev->dev.coherent_dma_mask = ~0;
 	dev->dev.of_node = of_node_get(node);
 	dev->dev.parent = parent;
 	dev->dev.platform_data = platform_data;
 	if (bus_id)
 		dev_set_name(&dev->dev, "%s", bus_id);
 	else
 		of_device_make_bus_id(&dev->dev);

 	/* Allow the HW Peripheral ID to be overridden */
 	prop = of_get_property(node, "arm,primecell-periphid", NULL);
 	if (prop)
 		dev->periphid = of_read_ulong(prop, 1);

 	/* Decode the IRQs and address ranges */
 	for (i = 0; i < AMBA_NR_IRQS; i++)
 		dev->irq[i] = irq_of_parse_and_map(node, i);

 	ret = of_address_to_resource(node, 0, &dev->res);
 	if (ret) {
 		pr_err("%s(): of_address_to_resource() failed (%d) for %s\n",
 		       __func__, ret, node->full_name);
 		goto err_free;
 	}

 	ret = amba_device_add(dev, &iomem_resource);
 	if (ret) {
 		pr_err("%s(): amba_device_add() failed (%d) for %s\n",
 		       __func__, ret, node->full_name);
 		goto err_free;
 	}

 	return dev;

 err_free:
 	amba_device_put(dev);
 err_clear_flag:
 	of_node_clear_flag(node, OF_POPULATED);
 	return NULL;
 }
 #else /* CONFIG_ARM_AMBA */
 static struct amba_device *of_amba_device_create(struct device_node *node,
 						 const char *bus_id,
 						 void *platform_data,
 						 struct device *parent)
 {
 	return NULL;
 }
 #endif /* CONFIG_ARM_AMBA */

 /**
  * of_devname_lookup() - Given a device node, lookup the preferred Linux name
  */
 static const struct of_dev_auxdata *of_dev_lookup(const struct of_dev_auxdata *lookup,
 				 struct device_node *np)
 {
 	struct resource res;

 	if (!lookup)
 		return NULL;

 	for(; lookup->compatible != NULL; lookup++) {
 		if (!of_device_is_compatible(np, lookup->compatible))
 			continue;
 		if (!of_address_to_resource(np, 0, &res))
 			if (res.start != lookup->phys_addr)
 				continue;
 		pr_debug("%s: devname=%s\n", np->full_name, lookup->name);
 		return lookup;
 	}

 	return NULL;
 }

 /**
  * of_platform_bus_create() - Create a device for a node and its children.
  * @bus: device node of the bus to instantiate
  * @matches: match table for bus nodes
  * @lookup: auxdata table for matching id and platform_data with device nodes
  * @parent: parent for new device, or NULL for top level.
  * @strict: require compatible property
  *
  * Creates a platform_device for the provided device_node, and optionally
  * recursively create devices for all the child nodes.
  */
 static int of_platform_bus_create(struct device_node *bus,
 				  const struct of_device_id *matches,
 				  const struct of_dev_auxdata *lookup,
 				  struct device *parent, bool strict)
 {
 	const struct of_dev_auxdata *auxdata;
 	struct device_node *child;
 	struct platform_device *dev;
 	const char *bus_id = NULL;
 	void *platform_data = NULL;
 	int rc = 0;

 	/* Make sure it has a compatible property */
 	if (strict && (!of_get_property(bus, "compatible", NULL))) {
 		pr_debug("%s() - skipping %s, no compatible prop\n",
 			 __func__, bus->full_name);
 		return 0;
 	}

 	auxdata = of_dev_lookup(lookup, bus);
 	if (auxdata) {
 		bus_id = auxdata->name;
 		platform_data = auxdata->platform_data;
 	}

 	if (of_device_is_compatible(bus, "arm,primecell")) {
 		/*
 		 * Don't return an error here to keep compatibility with older
 		 * device tree files.
 		 */
 		of_amba_device_create(bus, bus_id, platform_data, parent);
 		return 0;
 	}

 	dev = of_platform_device_create_pdata(bus, bus_id, platform_data, parent);
 	if (!dev || !of_match_node(matches, bus))
 		return 0;

 	for_each_child_of_node(bus, child) {
 		pr_debug("   create child: %s\n", child->full_name);
 		rc = of_platform_bus_create(child, matches, lookup, &dev->dev, strict);
 		if (rc) {
 			of_node_put(child);
 			break;
 		}
 	}
 	of_node_set_flag(bus, OF_POPULATED_BUS);
 	return rc;
 }

 /**
  * of_platform_bus_probe() - Probe the device-tree for platform buses
  * @root: parent of the first level to probe or NULL for the root of the tree
  * @matches: match table for bus nodes
  * @parent: parent to hook devices from, NULL for toplevel
  *
  * Note that children of the provided root are not instantiated as devices
  * unless the specified root itself matches the bus list and is not NULL.
  */
 int of_platform_bus_probe(struct device_node *root,
 			  const struct of_device_id *matches,
 			  struct device *parent)
 {
 	struct device_node *child;
 	int rc = 0;

 	root = root ? of_node_get(root) : of_find_node_by_path("/");
 	if (!root)
 		return -EINVAL;

 	pr_debug("of_platform_bus_probe()\n");
 	pr_debug(" starting at: %s\n", root->full_name);

 	/* Do a self check of bus type, if there's a match, create children */
 	if (of_match_node(matches, root)) {
 		rc = of_platform_bus_create(root, matches, NULL, parent, false);
 	} else for_each_child_of_node(root, child) {
 		if (!of_match_node(matches, child))
 			continue;
 		rc = of_platform_bus_create(child, matches, NULL, parent, false);
 		if (rc)
 			break;
 	}

 	of_node_put(root);
 	return rc;
 }
 EXPORT_SYMBOL(of_platform_bus_probe);

 /**
  * of_platform_populate() - Populate platform_devices from device tree data
  * @root: parent of the first level to probe or NULL for the root of the tree
  * @matches: match table, NULL to use the default
  * @lookup: auxdata table for matching id and platform_data with device nodes
  * @parent: parent to hook devices from, NULL for toplevel
  *
  * Similar to of_platform_bus_probe(), this function walks the device tree
  * and creates devices from nodes.  It differs in that it follows the modern
  * convention of requiring all device nodes to have a 'compatible' property,
  * and it is suitable for creating devices which are children of the root
  * node (of_platform_bus_probe will only create children of the root which
  * are selected by the @matches argument).
  *
  * New board support should be using this function instead of
  * of_platform_bus_probe().
  *
  * Returns 0 on success, < 0 on failure.
  */
 int of_platform_populate(struct device_node *root,
 			const struct of_device_id *matches,
 			const struct of_dev_auxdata *lookup,
 			struct device *parent)
 {
 	struct device_node *child;
 	int rc = 0;

 	root = root ? of_node_get(root) : of_find_node_by_path("/");
 	if (!root)
 		return -EINVAL;

 	for_each_child_of_node(root, child) {
 		rc = of_platform_bus_create(child, matches, lookup, parent, true);
 		if (rc)
 			break;
 	}

 	of_node_put(root);
 	return rc;
 }
 EXPORT_SYMBOL_GPL(of_platform_populate);

 static int of_platform_device_destroy(struct device *dev, void *data)
 {
 	/* Do not touch devices not populated from the device tree */
 	if (!dev->of_node || !of_node_check_flag(dev->of_node, OF_POPULATED))
 		return 0;

 	/* Recurse for any nodes that were treated as busses */
 	if (of_node_check_flag(dev->of_node, OF_POPULATED_BUS))
 		device_for_each_child(dev, NULL, of_platform_device_destroy);

 	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

 	of_node_clear_flag(dev->of_node, OF_POPULATED);
 	of_node_clear_flag(dev->of_node, OF_POPULATED_BUS);
 	return 0;
 }

 /**
  * of_platform_depopulate() - Remove devices populated from device tree
  * @parent: device which children 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.
  */
 void of_platform_depopulate(struct device *parent)
 {
 	device_for_each_child(parent, NULL, of_platform_device_destroy);
 }
 EXPORT_SYMBOL_GPL(of_platform_depopulate);

 #endif /* CONFIG_OF_ADDRESS */
	/*
	* Copyright (C) 2006 Benjamin Herrenschmidt, IBM Corp.
	* <benh@kernel.crashing.org>
	* and Arnd Bergmann, IBM Corp.
	* Merged from powerpc/kernel/of_platform.c and
	* sparc{,64}/kernel/of_device.c by Stephen Rothwell
	*
	* This program is free software; you can redistribute it and/or
	* modify it under the terms of the GNU General Public License
	* as published by the Free Software Foundation; either version
	* 2 of the License, or (at your option) any later version.
	*
	*/
	#include <linux/errno.h>
	#include <linux/module.h>
	#include <linux/amba/bus.h>
	#include <linux/device.h>
	#include <linux/dma-mapping.h>
	#include <linux/slab.h>
	#include <linux/of_address.h>
	#include <linux/of_device.h>
	#include <linux/of_irq.h>
	#include <linux/of_platform.h>
	#include <linux/platform_device.h>

	const struct of_device_id of_default_bus_match_table[] = {
	{ .compatible = "simple-bus", },
	#ifdef CONFIG_ARM_AMBA
	{ .compatible = "arm,amba-bus", },
	#endif /* CONFIG_ARM_AMBA */
	{} /* Empty terminated list */
	};

	static int of_dev_node_match(struct device dev, void data)
	{
	return dev->of_node == data;
	}

	/**
	* of_find_device_by_node - Find the platform_device associated with a node
	* @np: Pointer to device tree node
	*
	* Returns platform_device pointer, or NULL if not found
	*/
	struct platform_device of_find_device_by_node(struct device_node np)
	{
	struct device *dev;

	dev = bus_find_device(&platform_bus_type, NULL, np, of_dev_node_match);
	return dev ? to_platform_device(dev) : NULL;
	}
	EXPORT_SYMBOL(of_find_device_by_node);

	#ifdef CONFIG_OF_ADDRESS
	/*
	* The following routines scan a subtree and registers a device for
	* each applicable node.
	*
	* Note: sparc doesn't use these routines because it has a different
	* mechanism for creating devices from device tree nodes.
	*/

	/**
	* of_device_make_bus_id - Use the device node data to assign a unique name
	* @dev: pointer to device structure that is linked to a device tree node
	*
	* This routine will first try using the translated bus address to
	* derive a unique name. If it cannot, then it will prepend names from
	* parent nodes until a unique name can be derived.
	*/
	void of_device_make_bus_id(struct device *dev)
	{
	struct device_node *node = dev->of_node;
	const __be32 *reg;
	u64 addr;

	/* Construct the name, using parent nodes if necessary to ensure uniqueness */
	while (node->parent) {
	/*
	* If the address can be translated, then that is as much
	* uniqueness as we need. Make it the first component and return
	*/
	reg = of_get_property(node, "reg", NULL);
	if (reg && (addr = of_translate_address(node, reg)) != OF_BAD_ADDR) {
	dev_set_name(dev, dev_name(dev) ? "%llx.%s:%s" : "%llx.%s",
	(unsigned long long)addr, node->name,
	dev_name(dev));
	return;
	}

	/* format arguments only used if dev_name() resolves to NULL */
	dev_set_name(dev, dev_name(dev) ? "%s:%s" : "%s",
	strrchr(node->full_name, '/') + 1, dev_name(dev));
	node = node->parent;
	}
	}

	/**
	* of_device_alloc - Allocate and initialize an of_device
	* @np: device node to assign to device
	* @bus_id: Name to assign to the device. May be null to use default name.
	* @parent: Parent device.
	*/
	struct platform_device of_device_alloc(struct device_node np,
	const char *bus_id,
	struct device *parent)
	{
	struct platform_device *dev;
	int rc, i, num_reg = 0, num_irq;
	struct resource *res, temp_res;

	dev = platform_device_alloc("", -1);
	if (!dev)
	return NULL;

	/* count the io and irq resources */
	while (of_address_to_resource(np, num_reg, &temp_res) == 0)
	num_reg++;
	num_irq = of_irq_count(np);

	/* Populate the resource table */
	if (num_irq \|\| num_reg) {
	res = kzalloc(sizeof(res) (num_irq + num_reg), GFP_KERNEL);
	if (!res) {
	platform_device_put(dev);
	return NULL;
	}

	dev->num_resources = num_reg + num_irq;
	dev->resource = res;
	for (i = 0; i < num_reg; i++, res++) {
	rc = of_address_to_resource(np, i, res);
	WARN_ON(rc);
	}
	if (of_irq_to_resource_table(np, res, num_irq) != num_irq)
	pr_debug("not all legacy IRQ resources mapped for %s\n",
	np->name);
	}

	dev->dev.of_node = of_node_get(np);
	dev->dev.parent = parent;

	if (bus_id)
	dev_set_name(&dev->dev, "%s", bus_id);
	else
	of_device_make_bus_id(&dev->dev);

	return dev;
	}
	EXPORT_SYMBOL(of_device_alloc);

	/**
	* of_dma_configure - Setup DMA configuration
	* @dev: Device to apply DMA configuration
	*
	* Try to get devices's DMA configuration from DT and update it
	* accordingly.
	*
	* In case if platform code need to use own special DMA configuration,it
	* can use Platform bus notifier and handle BUS_NOTIFY_ADD_DEVICE event
	* to fix up DMA configuration.
	*/
	static void of_dma_configure(struct platform_device *pdev)
	{
	u64 dma_addr, paddr, size;
	int ret;
	struct device *dev = &pdev->dev;

	/*
	* Set default dma-mask to 32 bit. Drivers are expected to setup
	* the correct supported dma_mask.
	*/
	dev->coherent_dma_mask = DMA_BIT_MASK(32);

	/*
	* Set it to coherent_dma_mask by default if the architecture
	* code has not set it.
	*/
	if (!dev->dma_mask)
	dev->dma_mask = &dev->coherent_dma_mask;

	/*
	* if dma-coherent property exist, call arch hook to setup
	* dma coherent operations.
	*/
	if (of_dma_is_coherent(dev->of_node)) {
	set_arch_dma_coherent_ops(dev);
	dev_dbg(dev, "device is dma coherent\n");
	}

	/*
	* if dma-ranges property doesn't exist - just return else
	* setup the dma offset
	*/
	ret = of_dma_get_range(dev->of_node, &dma_addr, &paddr, &size);
	if (ret < 0) {
	dev_dbg(dev, "no dma range information to setup\n");
	return;
	}

	/* DMA ranges found. Calculate and set dma_pfn_offset */
	dev->dma_pfn_offset = PFN_DOWN(paddr - dma_addr);
	dev_dbg(dev, "dma_pfn_offset(%#08lx)\n", dev->dma_pfn_offset);
	}

	/**
	* of_platform_device_create_pdata - Alloc, initialize and register an of_device
	* @np: pointer to node to create device for
	* @bus_id: name to assign device
	* @platform_data: pointer to populate platform_data pointer with
	* @parent: Linux device model parent device.
	*
	* Returns pointer to created platform device, or NULL if a device was not
	* registered. Unavailable devices will not get registered.
	*/
	static struct platform_device *of_platform_device_create_pdata(
	struct device_node *np,
	const char *bus_id,
	void *platform_data,
	struct device *parent)
	{
	struct platform_device *dev;

	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)
	goto err_clear_flag;

	of_dma_configure(dev);
	dev->dev.bus = &platform_bus_type;
	dev->dev.platform_data = platform_data;

	/* We do not fill the DMA ops for platform devices by default.
	* This is currently the responsibility of the platform code
	* to do such, possibly using a device notifier
	*/

	if (of_device_add(dev) != 0) {
	platform_device_put(dev);
	goto err_clear_flag;
	}

	return dev;

	err_clear_flag:
	of_node_clear_flag(np, OF_POPULATED);
	return NULL;
	}

	/**
	* of_platform_device_create - Alloc, initialize and register an of_device
	* @np: pointer to node to create device for
	* @bus_id: name to assign device
	* @parent: Linux device model parent device.
	*
	* Returns pointer to created platform device, or NULL if a device was not
	* registered. Unavailable devices will not get registered.
	*/
	struct platform_device of_platform_device_create(struct device_node np,
	const char *bus_id,
	struct device *parent)
	{
	return of_platform_device_create_pdata(np, bus_id, NULL, parent);
	}
	EXPORT_SYMBOL(of_platform_device_create);

	#ifdef CONFIG_ARM_AMBA
	static struct amba_device of_amba_device_create(struct device_node node,
	const char *bus_id,
	void *platform_data,
	struct device *parent)
	{
	struct amba_device *dev;
	const void *prop;
	int i, ret;

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

	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);
	goto err_clear_flag;
	}

	/* setup generic device info */
	dev->dev.coherent_dma_mask = ~0;
	dev->dev.of_node = of_node_get(node);
	dev->dev.parent = parent;
	dev->dev.platform_data = platform_data;
	if (bus_id)
	dev_set_name(&dev->dev, "%s", bus_id);
	else
	of_device_make_bus_id(&dev->dev);

	/* Allow the HW Peripheral ID to be overridden */
	prop = of_get_property(node, "arm,primecell-periphid", NULL);
	if (prop)
	dev->periphid = of_read_ulong(prop, 1);

	/* Decode the IRQs and address ranges */
	for (i = 0; i < AMBA_NR_IRQS; i++)
	dev->irq[i] = irq_of_parse_and_map(node, i);

	ret = of_address_to_resource(node, 0, &dev->res);
	if (ret) {
	pr_err("%s(): of_address_to_resource() failed (%d) for %s\n",
	__func__, ret, node->full_name);
	goto err_free;
	}

	ret = amba_device_add(dev, &iomem_resource);
	if (ret) {
	pr_err("%s(): amba_device_add() failed (%d) for %s\n",
	__func__, ret, node->full_name);
	goto err_free;
	}

	return dev;

	err_free:
	amba_device_put(dev);
	err_clear_flag:
	of_node_clear_flag(node, OF_POPULATED);
	return NULL;
	}
	#else /* CONFIG_ARM_AMBA */
	static struct amba_device of_amba_device_create(struct device_node node,
	const char *bus_id,
	void *platform_data,
	struct device *parent)
	{
	return NULL;
	}
	#endif /* CONFIG_ARM_AMBA */

	/**
	* of_devname_lookup() - Given a device node, lookup the preferred Linux name
	*/
	static const struct of_dev_auxdata of_dev_lookup(const struct of_dev_auxdata lookup,
	struct device_node *np)
	{
	struct resource res;

	if (!lookup)
	return NULL;

	for(; lookup->compatible != NULL; lookup++) {
	if (!of_device_is_compatible(np, lookup->compatible))
	continue;
	if (!of_address_to_resource(np, 0, &res))
	if (res.start != lookup->phys_addr)
	continue;
	pr_debug("%s: devname=%s\n", np->full_name, lookup->name);
	return lookup;
	}

	return NULL;
	}

	/**
	* of_platform_bus_create() - Create a device for a node and its children.
	* @bus: device node of the bus to instantiate
	* @matches: match table for bus nodes
	* @lookup: auxdata table for matching id and platform_data with device nodes
	* @parent: parent for new device, or NULL for top level.
	* @strict: require compatible property
	*
	* Creates a platform_device for the provided device_node, and optionally
	* recursively create devices for all the child nodes.
	*/
	static int of_platform_bus_create(struct device_node *bus,
	const struct of_device_id *matches,
	const struct of_dev_auxdata *lookup,
	struct device *parent, bool strict)
	{
	const struct of_dev_auxdata *auxdata;
	struct device_node *child;
	struct platform_device *dev;
	const char *bus_id = NULL;
	void *platform_data = NULL;
	int rc = 0;

	/* Make sure it has a compatible property */
	if (strict && (!of_get_property(bus, "compatible", NULL))) {
	pr_debug("%s() - skipping %s, no compatible prop\n",
	__func__, bus->full_name);
	return 0;
	}

	auxdata = of_dev_lookup(lookup, bus);
	if (auxdata) {
	bus_id = auxdata->name;
	platform_data = auxdata->platform_data;
	}

	if (of_device_is_compatible(bus, "arm,primecell")) {
	/*
	* Don't return an error here to keep compatibility with older
	* device tree files.
	*/
	of_amba_device_create(bus, bus_id, platform_data, parent);
	return 0;
	}

	dev = of_platform_device_create_pdata(bus, bus_id, platform_data, parent);
	if (!dev \|\| !of_match_node(matches, bus))
	return 0;

	for_each_child_of_node(bus, child) {
	pr_debug(" create child: %s\n", child->full_name);
	rc = of_platform_bus_create(child, matches, lookup, &dev->dev, strict);
	if (rc) {
	of_node_put(child);
	break;
	}
	}
	of_node_set_flag(bus, OF_POPULATED_BUS);
	return rc;
	}

	/**
	* of_platform_bus_probe() - Probe the device-tree for platform buses
	* @root: parent of the first level to probe or NULL for the root of the tree
	* @matches: match table for bus nodes
	* @parent: parent to hook devices from, NULL for toplevel
	*
	* Note that children of the provided root are not instantiated as devices
	* unless the specified root itself matches the bus list and is not NULL.
	*/
	int of_platform_bus_probe(struct device_node *root,
	const struct of_device_id *matches,
	struct device *parent)
	{
	struct device_node *child;
	int rc = 0;

	root = root ? of_node_get(root) : of_find_node_by_path("/");
	if (!root)
	return -EINVAL;

	pr_debug("of_platform_bus_probe()\n");
	pr_debug(" starting at: %s\n", root->full_name);

	/* Do a self check of bus type, if there's a match, create children */
	if (of_match_node(matches, root)) {
	rc = of_platform_bus_create(root, matches, NULL, parent, false);
	} else for_each_child_of_node(root, child) {
	if (!of_match_node(matches, child))
	continue;
	rc = of_platform_bus_create(child, matches, NULL, parent, false);
	if (rc)
	break;
	}

	of_node_put(root);
	return rc;
	}
	EXPORT_SYMBOL(of_platform_bus_probe);

	/**
	* of_platform_populate() - Populate platform_devices from device tree data
	* @root: parent of the first level to probe or NULL for the root of the tree
	* @matches: match table, NULL to use the default
	* @lookup: auxdata table for matching id and platform_data with device nodes
	* @parent: parent to hook devices from, NULL for toplevel
	*
	* Similar to of_platform_bus_probe(), this function walks the device tree
	* and creates devices from nodes. It differs in that it follows the modern
	* convention of requiring all device nodes to have a 'compatible' property,
	* and it is suitable for creating devices which are children of the root
	* node (of_platform_bus_probe will only create children of the root which
	* are selected by the @matches argument).
	*
	* New board support should be using this function instead of
	* of_platform_bus_probe().
	*
	* Returns 0 on success, < 0 on failure.
	*/
	int of_platform_populate(struct device_node *root,
	const struct of_device_id *matches,
	const struct of_dev_auxdata *lookup,
	struct device *parent)
	{
	struct device_node *child;
	int rc = 0;

	root = root ? of_node_get(root) : of_find_node_by_path("/");
	if (!root)
	return -EINVAL;

	for_each_child_of_node(root, child) {
	rc = of_platform_bus_create(child, matches, lookup, parent, true);
	if (rc)
	break;
	}

	of_node_put(root);
	return rc;
	}
	EXPORT_SYMBOL_GPL(of_platform_populate);

	static int of_platform_device_destroy(struct device dev, void data)
	{
	/* Do not touch devices not populated from the device tree */
	if (!dev->of_node \|\| !of_node_check_flag(dev->of_node, OF_POPULATED))
	return 0;

	/* Recurse for any nodes that were treated as busses */
	if (of_node_check_flag(dev->of_node, OF_POPULATED_BUS))
	device_for_each_child(dev, NULL, of_platform_device_destroy);

	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

	of_node_clear_flag(dev->of_node, OF_POPULATED);
	of_node_clear_flag(dev->of_node, OF_POPULATED_BUS);
	return 0;
	}

	/**
	* of_platform_depopulate() - Remove devices populated from device tree
	* @parent: device which children 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.
	*/
	void of_platform_depopulate(struct device *parent)
	{
	device_for_each_child(parent, NULL, of_platform_device_destroy);
	}
	EXPORT_SYMBOL_GPL(of_platform_depopulate);

	#endif /* CONFIG_OF_ADDRESS */