[mirror_ubuntu-zesty-kernel.git] / drivers / of / base.c

/*
 * Procedures for creating, accessing and interpreting the device tree.
 *
 * Paul Mackerras       August 1996.
 * Copyright (C) 1996-2005 Paul Mackerras.
 *
 *  Adapted for 64bit PowerPC by Dave Engebretsen and Peter Bergner.
 *    {engebret|bergner}@us.ibm.com
 *
 *  Adapted for sparc and sparc64 by David S. Miller davem@davemloft.net
 *
 *  Reconsolidated from arch/x/kernel/prom.c by Stephen Rothwell and
 *  Grant Likely.
 *
 *      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.
 */

#define pr_fmt(fmt)     "OF: " fmt

#include <linux/console.h>
#include <linux/ctype.h>
#include <linux/cpu.h>
#include <linux/module.h>
#include <linux/of.h>
#include <linux/of_graph.h>
#include <linux/spinlock.h>
#include <linux/slab.h>
#include <linux/string.h>
#include <linux/proc_fs.h>

#include "of_private.h"

LIST_HEAD(aliases_lookup);

struct device_node *of_root;
EXPORT_SYMBOL(of_root);
struct device_node *of_chosen;
struct device_node *of_aliases;
struct device_node *of_stdout;
static const char *of_stdout_options;

struct kset *of_kset;

/*
 * Used to protect the of_aliases, to hold off addition of nodes to sysfs.
 * This mutex must be held whenever modifications are being made to the
 * device tree. The of_{attach,detach}_node() and
 * of_{add,remove,update}_property() helpers make sure this happens.
 */
DEFINE_MUTEX(of_mutex);

/* use when traversing tree through the child, sibling,
 * or parent members of struct device_node.
 */
DEFINE_RAW_SPINLOCK(devtree_lock);

int of_n_addr_cells(struct device_node *np)
{
        const __be32 *ip;

        do {
                if (np->parent)
                        np = np->parent;
                ip = of_get_property(np, "#address-cells", NULL);
                if (ip)
                        return be32_to_cpup(ip);
        } while (np->parent);
        /* No #address-cells property for the root node */
        return OF_ROOT_NODE_ADDR_CELLS_DEFAULT;
}
EXPORT_SYMBOL(of_n_addr_cells);

int of_n_size_cells(struct device_node *np)
{
        const __be32 *ip;

        do {
                if (np->parent)
                        np = np->parent;
                ip = of_get_property(np, "#size-cells", NULL);
                if (ip)
                        return be32_to_cpup(ip);
        } while (np->parent);
        /* No #size-cells property for the root node */
        return OF_ROOT_NODE_SIZE_CELLS_DEFAULT;
}
EXPORT_SYMBOL(of_n_size_cells);

#ifdef CONFIG_NUMA
int __weak of_node_to_nid(struct device_node *np)
{
        return NUMA_NO_NODE;
}
#endif

#ifndef CONFIG_OF_DYNAMIC
static void of_node_release(struct kobject *kobj)
{
        /* Without CONFIG_OF_DYNAMIC, no nodes gets freed */
}
#endif /* CONFIG_OF_DYNAMIC */

struct kobj_type of_node_ktype = {
        .release = of_node_release,
};

static ssize_t of_node_property_read(struct file *filp, struct kobject *kobj,
                                struct bin_attribute *bin_attr, char *buf,
                                loff_t offset, size_t count)
{
        struct property *pp = container_of(bin_attr, struct property, attr);
        return memory_read_from_buffer(buf, count, &offset, pp->value, pp->length);
}

/* always return newly allocated name, caller must free after use */
static const char *safe_name(struct kobject *kobj, const char *orig_name)
{
        const char *name = orig_name;
        struct kernfs_node *kn;
        int i = 0;

        /* don't be a hero. After 16 tries give up */
        while (i < 16 && (kn = sysfs_get_dirent(kobj->sd, name))) {
                sysfs_put(kn);
                if (name != orig_name)
                        kfree(name);
                name = kasprintf(GFP_KERNEL, "%s#%i", orig_name, ++i);
        }

        if (name == orig_name) {
                name = kstrdup(orig_name, GFP_KERNEL);
        } else {
                pr_warn("Duplicate name in %s, renamed to \"%s\"\n",
                        kobject_name(kobj), name);
        }
        return name;
}

int __of_add_property_sysfs(struct device_node *np, struct property *pp)
{
        int rc;

        /* Important: Don't leak passwords */
        bool secure = strncmp(pp->name, "security-", 9) == 0;

        if (!IS_ENABLED(CONFIG_SYSFS))
                return 0;

        if (!of_kset || !of_node_is_attached(np))
                return 0;

        sysfs_bin_attr_init(&pp->attr);
        pp->attr.attr.name = safe_name(&np->kobj, pp->name);
        pp->attr.attr.mode = secure ? S_IRUSR : S_IRUGO;
        pp->attr.size = secure ? 0 : pp->length;
        pp->attr.read = of_node_property_read;

        rc = sysfs_create_bin_file(&np->kobj, &pp->attr);
        WARN(rc, "error adding attribute %s to node %s\n", pp->name, np->full_name);
        return rc;
}

int __of_attach_node_sysfs(struct device_node *np)
{
        const char *name;
        struct kobject *parent;
        struct property *pp;
        int rc;

        if (!IS_ENABLED(CONFIG_SYSFS))
                return 0;

        if (!of_kset)
                return 0;

        np->kobj.kset = of_kset;
        if (!np->parent) {
                /* Nodes without parents are new top level trees */
                name = safe_name(&of_kset->kobj, "base");
                parent = NULL;
        } else {
                name = safe_name(&np->parent->kobj, kbasename(np->full_name));
                parent = &np->parent->kobj;
        }
        if (!name)
                return -ENOMEM;
        rc = kobject_add(&np->kobj, parent, "%s", name);
        kfree(name);
        if (rc)
                return rc;

        for_each_property_of_node(np, pp)
                __of_add_property_sysfs(np, pp);

        return 0;
}

void __init of_core_init(void)
{
        struct device_node *np;

        /* Create the kset, and register existing nodes */
        mutex_lock(&of_mutex);
        of_kset = kset_create_and_add("devicetree", NULL, firmware_kobj);
        if (!of_kset) {
                mutex_unlock(&of_mutex);
                pr_err("failed to register existing nodes\n");
                return;
        }
        for_each_of_allnodes(np)
                __of_attach_node_sysfs(np);
        mutex_unlock(&of_mutex);

        /* Symlink in /proc as required by userspace ABI */
        if (of_root)
                proc_symlink("device-tree", NULL, "/sys/firmware/devicetree/base");
}

static struct property *__of_find_property(const struct device_node *np,
                                           const char *name, int *lenp)
{
        struct property *pp;

        if (!np)
                return NULL;

        for (pp = np->properties; pp; pp = pp->next) {
                if (of_prop_cmp(pp->name, name) == 0) {
                        if (lenp)
                                *lenp = pp->length;
                        break;
                }
        }

        return pp;
}

struct property *of_find_property(const struct device_node *np,
                                  const char *name,
                                  int *lenp)
{
        struct property *pp;
        unsigned long flags;

        raw_spin_lock_irqsave(&devtree_lock, flags);
        pp = __of_find_property(np, name, lenp);
        raw_spin_unlock_irqrestore(&devtree_lock, flags);

        return pp;
}
EXPORT_SYMBOL(of_find_property);

struct device_node *__of_find_all_nodes(struct device_node *prev)
{
        struct device_node *np;
        if (!prev) {
                np = of_root;
        } else if (prev->child) {
                np = prev->child;
        } else {
                /* Walk back up looking for a sibling, or the end of the structure */
                np = prev;
                while (np->parent && !np->sibling)
                        np = np->parent;
                np = np->sibling; /* Might be null at the end of the tree */
        }
        return np;
}

/**
 * of_find_all_nodes - Get next node in global list
 * @prev:       Previous node or NULL to start iteration
 *              of_node_put() will be called on it
 *
 * Returns a node pointer with refcount incremented, use
 * of_node_put() on it when done.
 */
struct device_node *of_find_all_nodes(struct device_node *prev)
{
        struct device_node *np;
        unsigned long flags;

        raw_spin_lock_irqsave(&devtree_lock, flags);
        np = __of_find_all_nodes(prev);
        of_node_get(np);
        of_node_put(prev);
        raw_spin_unlock_irqrestore(&devtree_lock, flags);
        return np;
}
EXPORT_SYMBOL(of_find_all_nodes);

/*
 * Find a property with a given name for a given node
 * and return the value.
 */
const void *__of_get_property(const struct device_node *np,
                              const char *name, int *lenp)
{
        struct property *pp = __of_find_property(np, name, lenp);

        return pp ? pp->value : NULL;
}

/*
 * Find a property with a given name for a given node
 * and return the value.
 */
const void *of_get_property(const struct device_node *np, const char *name,
                            int *lenp)
{
        struct property *pp = of_find_property(np, name, lenp);

        return pp ? pp->value : NULL;
}
EXPORT_SYMBOL(of_get_property);

/*
 * arch_match_cpu_phys_id - Match the given logical CPU and physical id
 *
 * @cpu: logical cpu index of a core/thread
 * @phys_id: physical identifier of a core/thread
 *
 * CPU logical to physical index mapping is architecture specific.
 * However this __weak function provides a default match of physical
 * id to logical cpu index. phys_id provided here is usually values read
 * from the device tree which must match the hardware internal registers.
 *
 * Returns true if the physical identifier and the logical cpu index
 * correspond to the same core/thread, false otherwise.
 */
bool __weak arch_match_cpu_phys_id(int cpu, u64 phys_id)
{
        return (u32)phys_id == cpu;
}

/**
 * Checks if the given "prop_name" property holds the physical id of the
 * core/thread corresponding to the logical cpu 'cpu'. If 'thread' is not
 * NULL, local thread number within the core is returned in it.
 */
static bool __of_find_n_match_cpu_property(struct device_node *cpun,
                        const char *prop_name, int cpu, unsigned int *thread)
{
        const __be32 *cell;
        int ac, prop_len, tid;
        u64 hwid;

        ac = of_n_addr_cells(cpun);
        cell = of_get_property(cpun, prop_name, &prop_len);
        if (!cell || !ac)
                return false;
        prop_len /= sizeof(*cell) * ac;
        for (tid = 0; tid < prop_len; tid++) {
                hwid = of_read_number(cell, ac);
                if (arch_match_cpu_phys_id(cpu, hwid)) {
                        if (thread)
                                *thread = tid;
                        return true;
                }
                cell += ac;
        }
        return false;
}

/*
 * arch_find_n_match_cpu_physical_id - See if the given device node is
 * for the cpu corresponding to logical cpu 'cpu'.  Return true if so,
 * else false.  If 'thread' is non-NULL, the local thread number within the
 * core is returned in it.
 */
bool __weak arch_find_n_match_cpu_physical_id(struct device_node *cpun,
                                              int cpu, unsigned int *thread)
{
        /* Check for non-standard "ibm,ppc-interrupt-server#s" property
         * for thread ids on PowerPC. If it doesn't exist fallback to
         * standard "reg" property.
         */
        if (IS_ENABLED(CONFIG_PPC) &&
            __of_find_n_match_cpu_property(cpun,
                                           "ibm,ppc-interrupt-server#s",
                                           cpu, thread))
                return true;

        return __of_find_n_match_cpu_property(cpun, "reg", cpu, thread);
}

/**
 * of_get_cpu_node - Get device node associated with the given logical CPU
 *
 * @cpu: CPU number(logical index) for which device node is required
 * @thread: if not NULL, local thread number within the physical core is
 *          returned
 *
 * The main purpose of this function is to retrieve the device node for the
 * given logical CPU index. It should be used to initialize the of_node in
 * cpu device. Once of_node in cpu device is populated, all the further
 * references can use that instead.
 *
 * CPU logical to physical index mapping is architecture specific and is built
 * before booting secondary cores. This function uses arch_match_cpu_phys_id
 * which can be overridden by architecture specific implementation.
 *
 * Returns a node pointer for the logical cpu with refcount incremented, use
 * of_node_put() on it when done. Returns NULL if not found.
 */
struct device_node *of_get_cpu_node(int cpu, unsigned int *thread)
{
        struct device_node *cpun;

        for_each_node_by_type(cpun, "cpu") {
                if (arch_find_n_match_cpu_physical_id(cpun, cpu, thread))
                        return cpun;
        }
        return NULL;
}
EXPORT_SYMBOL(of_get_cpu_node);

/**
 * __of_device_is_compatible() - Check if the node matches given constraints
 * @device: pointer to node
 * @compat: required compatible string, NULL or "" for any match
 * @type: required device_type value, NULL or "" for any match
 * @name: required node name, NULL or "" for any match
 *
 * Checks if the given @compat, @type and @name strings match the
 * properties of the given @device. A constraints can be skipped by
 * passing NULL or an empty string as the constraint.
 *
 * Returns 0 for no match, and a positive integer on match. The return
 * value is a relative score with larger values indicating better
 * matches. The score is weighted for the most specific compatible value
 * to get the highest score. Matching type is next, followed by matching
 * name. Practically speaking, this results in the following priority
 * order for matches:
 *
 * 1. specific compatible && type && name
 * 2. specific compatible && type
 * 3. specific compatible && name
 * 4. specific compatible
 * 5. general compatible && type && name
 * 6. general compatible && type
 * 7. general compatible && name
 * 8. general compatible
 * 9. type && name
 * 10. type
 * 11. name
 */
static int __of_device_is_compatible(const struct device_node *device,
                                     const char *compat, const char *type, const char *name)
{
        struct property *prop;
        const char *cp;
        int index = 0, score = 0;

        /* Compatible match has highest priority */
        if (compat && compat[0]) {
                prop = __of_find_property(device, "compatible", NULL);
                for (cp = of_prop_next_string(prop, NULL); cp;
                     cp = of_prop_next_string(prop, cp), index++) {
                        if (of_compat_cmp(cp, compat, strlen(compat)) == 0) {
                                score = INT_MAX/2 - (index << 2);
                                break;
                        }
                }
                if (!score)
                        return 0;
        }

        /* Matching type is better than matching name */
        if (type && type[0]) {
                if (!device->type || of_node_cmp(type, device->type))
                        return 0;
                score += 2;
        }

        /* Matching name is a bit better than not */
        if (name && name[0]) {
                if (!device->name || of_node_cmp(name, device->name))
                        return 0;
                score++;
        }

        return score;
}

/** Checks if the given "compat" string matches one of the strings in
 * the device's "compatible" property
 */
int of_device_is_compatible(const struct device_node *device,
                const char *compat)
{
        unsigned long flags;
        int res;

        raw_spin_lock_irqsave(&devtree_lock, flags);
        res = __of_device_is_compatible(device, compat, NULL, NULL);
        raw_spin_unlock_irqrestore(&devtree_lock, flags);
        return res;
}
EXPORT_SYMBOL(of_device_is_compatible);

/** Checks if the device is compatible with any of the entries in
 *  a NULL terminated array of strings. Returns the best match
 *  score or 0.
 */
int of_device_compatible_match(struct device_node *device,
                               const char *const *compat)
{
        unsigned int tmp, score = 0;

        if (!compat)
                return 0;

        while (*compat) {
                tmp = of_device_is_compatible(device, *compat);
                if (tmp > score)
                        score = tmp;
                compat++;
        }

        return score;
}

/**
 * of_machine_is_compatible - Test root of device tree for a given compatible value
 * @compat: compatible string to look for in root node's compatible property.
 *
 * Returns a positive integer if the root node has the given value in its
 * compatible property.
 */
int of_machine_is_compatible(const char *compat)
{
        struct device_node *root;
        int rc = 0;

        root = of_find_node_by_path("/");
        if (root) {
                rc = of_device_is_compatible(root, compat);
                of_node_put(root);
        }
        return rc;
}
EXPORT_SYMBOL(of_machine_is_compatible);

/**
 *  __of_device_is_available - check if a device is available for use
 *
 *  @device: Node to check for availability, with locks already held
 *
 *  Returns true if the status property is absent or set to "okay" or "ok",
 *  false otherwise
 */
static bool __of_device_is_available(const struct device_node *device)
{
        const char *status;
        int statlen;

        if (!device)
                return false;

        status = __of_get_property(device, "status", &statlen);
        if (status == NULL)
                return true;

        if (statlen > 0) {
                if (!strcmp(status, "okay") || !strcmp(status, "ok"))
                        return true;
        }

        return false;
}

/**
 *  of_device_is_available - check if a device is available for use
 *
 *  @device: Node to check for availability
 *
 *  Returns true if the status property is absent or set to "okay" or "ok",
 *  false otherwise
 */
bool of_device_is_available(const struct device_node *device)
{
        unsigned long flags;
        bool res;

        raw_spin_lock_irqsave(&devtree_lock, flags);
        res = __of_device_is_available(device);
        raw_spin_unlock_irqrestore(&devtree_lock, flags);
        return res;

}
EXPORT_SYMBOL(of_device_is_available);

/**
 *  of_device_is_big_endian - check if a device has BE registers
 *
 *  @device: Node to check for endianness
 *
 *  Returns true if the device has a "big-endian" property, or if the kernel
 *  was compiled for BE *and* the device has a "native-endian" property.
 *  Returns false otherwise.
 *
 *  Callers would nominally use ioread32be/iowrite32be if
 *  of_device_is_big_endian() == true, or readl/writel otherwise.
 */
bool of_device_is_big_endian(const struct device_node *device)
{
        if (of_property_read_bool(device, "big-endian"))
                return true;
        if (IS_ENABLED(CONFIG_CPU_BIG_ENDIAN) &&
            of_property_read_bool(device, "native-endian"))
                return true;
        return false;
}
EXPORT_SYMBOL(of_device_is_big_endian);

/**
 *      of_get_parent - Get a node's parent if any
 *      @node:  Node to get parent
 *
 *      Returns a node pointer with refcount incremented, use
 *      of_node_put() on it when done.
 */
struct device_node *of_get_parent(const struct device_node *node)
{
        struct device_node *np;
        unsigned long flags;

        if (!node)
                return NULL;

        raw_spin_lock_irqsave(&devtree_lock, flags);
        np = of_node_get(node->parent);
        raw_spin_unlock_irqrestore(&devtree_lock, flags);
        return np;
}
EXPORT_SYMBOL(of_get_parent);

/**
 *      of_get_next_parent - Iterate to a node's parent
 *      @node:  Node to get parent of
 *
 *      This is like of_get_parent() except that it drops the
 *      refcount on the passed node, making it suitable for iterating
 *      through a node's parents.
 *
 *      Returns a node pointer with refcount incremented, use
 *      of_node_put() on it when done.
 */
struct device_node *of_get_next_parent(struct device_node *node)
{
        struct device_node *parent;
        unsigned long flags;

        if (!node)
                return NULL;

        raw_spin_lock_irqsave(&devtree_lock, flags);
        parent = of_node_get(node->parent);
        of_node_put(node);
        raw_spin_unlock_irqrestore(&devtree_lock, flags);
        return parent;
}
EXPORT_SYMBOL(of_get_next_parent);

static struct device_node *__of_get_next_child(const struct device_node *node,
                                                struct device_node *prev)
{
        struct device_node *next;

        if (!node)
                return NULL;

        next = prev ? prev->sibling : node->child;
        for (; next; next = next->sibling)
                if (of_node_get(next))
                        break;
        of_node_put(prev);
        return next;
}
#define __for_each_child_of_node(parent, child) \
        for (child = __of_get_next_child(parent, NULL); child != NULL; \
             child = __of_get_next_child(parent, child))

/**
 *      of_get_next_child - Iterate a node childs
 *      @node:  parent node
 *      @prev:  previous child of the parent node, or NULL to get first
 *
 *      Returns a node pointer with refcount incremented, use of_node_put() on
 *      it when done. Returns NULL when prev is the last child. Decrements the
 *      refcount of prev.
 */
struct device_node *of_get_next_child(const struct device_node *node,
        struct device_node *prev)
{
        struct device_node *next;
        unsigned long flags;

        raw_spin_lock_irqsave(&devtree_lock, flags);
        next = __of_get_next_child(node, prev);
        raw_spin_unlock_irqrestore(&devtree_lock, flags);
        return next;
}
EXPORT_SYMBOL(of_get_next_child);

/**
 *      of_get_next_available_child - Find the next available child node
 *      @node:  parent node
 *      @prev:  previous child of the parent node, or NULL to get first
 *
 *      This function is like of_get_next_child(), except that it
 *      automatically skips any disabled nodes (i.e. status = "disabled").
 */
struct device_node *of_get_next_available_child(const struct device_node *node,
        struct device_node *prev)
{
        struct device_node *next;
        unsigned long flags;

        if (!node)
                return NULL;

        raw_spin_lock_irqsave(&devtree_lock, flags);
        next = prev ? prev->sibling : node->child;
        for (; next; next = next->sibling) {
                if (!__of_device_is_available(next))
                        continue;
                if (of_node_get(next))
                        break;
        }
        of_node_put(prev);
        raw_spin_unlock_irqrestore(&devtree_lock, flags);
        return next;
}
EXPORT_SYMBOL(of_get_next_available_child);

/**
 *      of_get_child_by_name - Find the child node by name for a given parent
 *      @node:  parent node
 *      @name:  child name to look for.
 *
 *      This function looks for child node for given matching name
 *
 *      Returns a node pointer if found, with refcount incremented, use
 *      of_node_put() on it when done.
 *      Returns NULL if node is not found.
 */
struct device_node *of_get_child_by_name(const struct device_node *node,
                                const char *name)
{
        struct device_node *child;

        for_each_child_of_node(node, child)
                if (child->name && (of_node_cmp(child->name, name) == 0))
                        break;
        return child;
}
EXPORT_SYMBOL(of_get_child_by_name);

static struct device_node *__of_find_node_by_path(struct device_node *parent,
                                                const char *path)
{
        struct device_node *child;
        int len;

        len = strcspn(path, "/:");
        if (!len)
                return NULL;

        __for_each_child_of_node(parent, child) {
                const char *name = strrchr(child->full_name, '/');
                if (WARN(!name, "malformed device_node %s\n", child->full_name))
                        continue;
                name++;
                if (strncmp(path, name, len) == 0 && (strlen(name) == len))
                        return child;
        }
        return NULL;
}

/**
 *      of_find_node_opts_by_path - Find a node matching a full OF path
 *      @path: Either the full path to match, or if the path does not
 *             start with '/', the name of a property of the /aliases
 *             node (an alias).  In the case of an alias, the node
 *             matching the alias' value will be returned.
 *      @opts: Address of a pointer into which to store the start of
 *             an options string appended to the end of the path with
 *             a ':' separator.
 *
 *      Valid paths:
 *              /foo/bar        Full path
 *              foo             Valid alias
 *              foo/bar         Valid alias + relative path
 *
 *      Returns a node pointer with refcount incremented, use
 *      of_node_put() on it when done.
 */
struct device_node *of_find_node_opts_by_path(const char *path, const char **opts)
{
        struct device_node *np = NULL;
        struct property *pp;
        unsigned long flags;
        const char *separator = strchr(path, ':');

        if (opts)
                *opts = separator ? separator + 1 : NULL;

        if (strcmp(path, "/") == 0)
                return of_node_get(of_root);

        /* The path could begin with an alias */
        if (*path != '/') {
                int len;
                const char *p = separator;

                if (!p)
                        p = strchrnul(path, '/');
                len = p - path;

                /* of_aliases must not be NULL */
                if (!of_aliases)
                        return NULL;

                for_each_property_of_node(of_aliases, pp) {
                        if (strlen(pp->name) == len && !strncmp(pp->name, path, len)) {
                                np = of_find_node_by_path(pp->value);
                                break;
                        }
                }
                if (!np)
                        return NULL;
                path = p;
        }

        /* Step down the tree matching path components */
        raw_spin_lock_irqsave(&devtree_lock, flags);
        if (!np)
                np = of_node_get(of_root);
        while (np && *path == '/') {
                path++; /* Increment past '/' delimiter */
                np = __of_find_node_by_path(np, path);
                path = strchrnul(path, '/');
                if (separator && separator < path)
                        break;
        }
        raw_spin_unlock_irqrestore(&devtree_lock, flags);
        return np;
}
EXPORT_SYMBOL(of_find_node_opts_by_path);

/**
 *      of_find_node_by_name - Find a node by its "name" property
 *      @from:  The node to start searching from or NULL, the node
 *              you pass will not be searched, only the next one
 *              will; typically, you pass what the previous call
 *              returned. of_node_put() will be called on it
 *      @name:  The name string to match against
 *
 *      Returns a node pointer with refcount incremented, use
 *      of_node_put() on it when done.
 */
struct device_node *of_find_node_by_name(struct device_node *from,
        const char *name)
{
        struct device_node *np;
        unsigned long flags;

        raw_spin_lock_irqsave(&devtree_lock, flags);
        for_each_of_allnodes_from(from, np)
                if (np->name && (of_node_cmp(np->name, name) == 0)
                    && of_node_get(np))
                        break;
        of_node_put(from);
        raw_spin_unlock_irqrestore(&devtree_lock, flags);
        return np;
}
EXPORT_SYMBOL(of_find_node_by_name);

/**
 *      of_find_node_by_type - Find a node by its "device_type" property
 *      @from:  The node to start searching from, or NULL to start searching
 *              the entire device tree. The node you pass will not be
 *              searched, only the next one will; typically, you pass
 *              what the previous call returned. of_node_put() will be
 *              called on from for you.
 *      @type:  The type string to match against
 *
 *      Returns a node pointer with refcount incremented, use
 *      of_node_put() on it when done.
 */
struct device_node *of_find_node_by_type(struct device_node *from,
        const char *type)
{
        struct device_node *np;
        unsigned long flags;

        raw_spin_lock_irqsave(&devtree_lock, flags);
        for_each_of_allnodes_from(from, np)
                if (np->type && (of_node_cmp(np->type, type) == 0)
                    && of_node_get(np))
                        break;
        of_node_put(from);
        raw_spin_unlock_irqrestore(&devtree_lock, flags);
        return np;
}
EXPORT_SYMBOL(of_find_node_by_type);

/**
 *      of_find_compatible_node - Find a node based on type and one of the
 *                                tokens in its "compatible" property
 *      @from:          The node to start searching from or NULL, the node
 *                      you pass will not be searched, only the next one
 *                      will; typically, you pass what the previous call
 *                      returned. of_node_put() will be called on it
 *      @type:          The type string to match "device_type" or NULL to ignore
 *      @compatible:    The string to match to one of the tokens in the device
 *                      "compatible" list.
 *
 *      Returns a node pointer with refcount incremented, use
 *      of_node_put() on it when done.
 */
struct device_node *of_find_compatible_node(struct device_node *from,
        const char *type, const char *compatible)
{
        struct device_node *np;
        unsigned long flags;

        raw_spin_lock_irqsave(&devtree_lock, flags);
        for_each_of_allnodes_from(from, np)
                if (__of_device_is_compatible(np, compatible, type, NULL) &&
                    of_node_get(np))
                        break;
        of_node_put(from);
        raw_spin_unlock_irqrestore(&devtree_lock, flags);
        return np;
}
EXPORT_SYMBOL(of_find_compatible_node);

/**
 *      of_find_node_with_property - Find a node which has a property with
 *                                   the given name.
 *      @from:          The node to start searching from or NULL, the node
 *                      you pass will not be searched, only the next one
 *                      will; typically, you pass what the previous call
 *                      returned. of_node_put() will be called on it
 *      @prop_name:     The name of the property to look for.
 *
 *      Returns a node pointer with refcount incremented, use
 *      of_node_put() on it when done.
 */
struct device_node *of_find_node_with_property(struct device_node *from,
        const char *prop_name)
{
        struct device_node *np;
        struct property *pp;
        unsigned long flags;

        raw_spin_lock_irqsave(&devtree_lock, flags);
        for_each_of_allnodes_from(from, np) {
                for (pp = np->properties; pp; pp = pp->next) {
                        if (of_prop_cmp(pp->name, prop_name) == 0) {
                                of_node_get(np);
                                goto out;
                        }
                }
        }
out:
        of_node_put(from);
        raw_spin_unlock_irqrestore(&devtree_lock, flags);
        return np;
}
EXPORT_SYMBOL(of_find_node_with_property);

static
const struct of_device_id *__of_match_node(const struct of_device_id *matches,
                                           const struct device_node *node)
{
        const struct of_device_id *best_match = NULL;
        int score, best_score = 0;

        if (!matches)
                return NULL;

        for (; matches->name[0] || matches->type[0] || matches->compatible[0]; matches++) {
                score = __of_device_is_compatible(node, matches->compatible,
                                                  matches->type, matches->name);
                if (score > best_score) {
                        best_match = matches;
                        best_score = score;
                }
        }

        return best_match;
}

/**
 * of_match_node - Tell if a device_node has a matching of_match structure
 *      @matches:       array of of device match structures to search in
 *      @node:          the of device structure to match against
 *
 *      Low level utility function used by device matching.
 */
const struct of_device_id *of_match_node(const struct of_device_id *matches,
                                         const struct device_node *node)
{
        const struct of_device_id *match;
        unsigned long flags;

        raw_spin_lock_irqsave(&devtree_lock, flags);
        match = __of_match_node(matches, node);
        raw_spin_unlock_irqrestore(&devtree_lock, flags);
        return match;
}
EXPORT_SYMBOL(of_match_node);

/**
 *      of_find_matching_node_and_match - Find a node based on an of_device_id
 *                                        match table.
 *      @from:          The node to start searching from or NULL, the node
 *                      you pass will not be searched, only the next one
 *                      will; typically, you pass what the previous call
 *                      returned. of_node_put() will be called on it
 *      @matches:       array of of device match structures to search in
 *      @match          Updated to point at the matches entry which matched
 *
 *      Returns a node pointer with refcount incremented, use
 *      of_node_put() on it when done.
 */
struct device_node *of_find_matching_node_and_match(struct device_node *from,
                                        const struct of_device_id *matches,
                                        const struct of_device_id **match)
{
        struct device_node *np;
        const struct of_device_id *m;
        unsigned long flags;

        if (match)
                *match = NULL;

        raw_spin_lock_irqsave(&devtree_lock, flags);
        for_each_of_allnodes_from(from, np) {
                m = __of_match_node(matches, np);
                if (m && of_node_get(np)) {
                        if (match)
                                *match = m;
                        break;
                }
        }
        of_node_put(from);
        raw_spin_unlock_irqrestore(&devtree_lock, flags);
        return np;
}
EXPORT_SYMBOL(of_find_matching_node_and_match);

/**
 * of_modalias_node - Lookup appropriate modalias for a device node
 * @node:       pointer to a device tree node
 * @modalias:   Pointer to buffer that modalias value will be copied into
 * @len:        Length of modalias value
 *
 * Based on the value of the compatible property, this routine will attempt
 * to choose an appropriate modalias value for a particular device tree node.
 * It does this by stripping the manufacturer prefix (as delimited by a ',')
 * from the first entry in the compatible list property.
 *
 * This routine returns 0 on success, <0 on failure.
 */
int of_modalias_node(struct device_node *node, char *modalias, int len)
{
        const char *compatible, *p;
        int cplen;

        compatible = of_get_property(node, "compatible", &cplen);
        if (!compatible || strlen(compatible) > cplen)
                return -ENODEV;
        p = strchr(compatible, ',');
        strlcpy(modalias, p ? p + 1 : compatible, len);
        return 0;
}
EXPORT_SYMBOL_GPL(of_modalias_node);

/**
 * of_find_node_by_phandle - Find a node given a phandle
 * @handle:     phandle of the node to find
 *
 * Returns a node pointer with refcount incremented, use
 * of_node_put() on it when done.
 */
struct device_node *of_find_node_by_phandle(phandle handle)
{
        struct device_node *np;
        unsigned long flags;

        if (!handle)
                return NULL;

        raw_spin_lock_irqsave(&devtree_lock, flags);
        for_each_of_allnodes(np)
                if (np->phandle == handle)
                        break;
        of_node_get(np);
        raw_spin_unlock_irqrestore(&devtree_lock, flags);
        return np;
}
EXPORT_SYMBOL(of_find_node_by_phandle);

/**
 * of_property_count_elems_of_size - Count the number of elements in a property
 *
 * @np:         device node from which the property value is to be read.
 * @propname:   name of the property to be searched.
 * @elem_size:  size of the individual element
 *
 * Search for a property in a device node and count the number of elements of
 * size elem_size in it. Returns number of elements on sucess, -EINVAL if the
 * property does not exist or its length does not match a multiple of elem_size
 * and -ENODATA if the property does not have a value.
 */
int of_property_count_elems_of_size(const struct device_node *np,
                                const char *propname, int elem_size)
{
        struct property *prop = of_find_property(np, propname, NULL);

        if (!prop)
                return -EINVAL;
        if (!prop->value)
                return -ENODATA;

        if (prop->length % elem_size != 0) {
                pr_err("size of %s in node %s is not a multiple of %d\n",
                       propname, np->full_name, elem_size);
                return -EINVAL;
        }

        return prop->length / elem_size;
}
EXPORT_SYMBOL_GPL(of_property_count_elems_of_size);

/**
 * of_find_property_value_of_size
 *
 * @np:         device node from which the property value is to be read.
 * @propname:   name of the property to be searched.
 * @min:        minimum allowed length of property value
 * @max:        maximum allowed length of property value (0 means unlimited)
 * @len:        if !=NULL, actual length is written to here
 *
 * Search for a property in a device node and valid the requested size.
 * Returns the property value on success, -EINVAL if the property does not
 *  exist, -ENODATA if property does not have a value, and -EOVERFLOW if the
 * property data is too small or too large.
 *
 */
static void *of_find_property_value_of_size(const struct device_node *np,
                        const char *propname, u32 min, u32 max, size_t *len)
{
        struct property *prop = of_find_property(np, propname, NULL);

        if (!prop)
                return ERR_PTR(-EINVAL);
        if (!prop->value)
                return ERR_PTR(-ENODATA);
        if (prop->length < min)
                return ERR_PTR(-EOVERFLOW);
        if (max && prop->length > max)
                return ERR_PTR(-EOVERFLOW);

        if (len)
                *len = prop->length;

        return prop->value;
}

/**
 * of_property_read_u32_index - Find and read a u32 from a multi-value property.
 *
 * @np:         device node from which the property value is to be read.
 * @propname:   name of the property to be searched.
 * @index:      index of the u32 in the list of values
 * @out_value:  pointer to return value, modified only if no error.
 *
 * Search for a property in a device node and read nth 32-bit value from
 * it. Returns 0 on success, -EINVAL if the property does not exist,
 * -ENODATA if property does not have a value, and -EOVERFLOW if the
 * property data isn't large enough.
 *
 * The out_value is modified only if a valid u32 value can be decoded.
 */
int of_property_read_u32_index(const struct device_node *np,
                                       const char *propname,
                                       u32 index, u32 *out_value)
{
        const u32 *val = of_find_property_value_of_size(np, propname,
                                        ((index + 1) * sizeof(*out_value)),
                                        0,
                                        NULL);

        if (IS_ERR(val))
                return PTR_ERR(val);

        *out_value = be32_to_cpup(((__be32 *)val) + index);
        return 0;
}
EXPORT_SYMBOL_GPL(of_property_read_u32_index);

/**
 * of_property_read_variable_u8_array - Find and read an array of u8 from a
 * property, with bounds on the minimum and maximum array size.
 *
 * @np:         device node from which the property value is to be read.
 * @propname:   name of the property to be searched.
 * @out_values: pointer to return value, modified only if return value is 0.
 * @sz_min:     minimum number of array elements to read
 * @sz_max:     maximum number of array elements to read, if zero there is no
 *              upper limit on the number of elements in the dts entry but only
 *              sz_min will be read.
 *
 * Search for a property in a device node and read 8-bit value(s) from
 * it. Returns number of elements read on success, -EINVAL if the property
 * does not exist, -ENODATA if property does not have a value, and -EOVERFLOW
 * if the property data is smaller than sz_min or longer than sz_max.
 *
 * dts entry of array should be like:
 *      property = /bits/ 8 <0x50 0x60 0x70>;
 *
 * The out_values is modified only if a valid u8 value can be decoded.
 */
int of_property_read_variable_u8_array(const struct device_node *np,
                                        const char *propname, u8 *out_values,
                                        size_t sz_min, size_t sz_max)
{
        size_t sz, count;
        const u8 *val = of_find_property_value_of_size(np, propname,
                                                (sz_min * sizeof(*out_values)),
                                                (sz_max * sizeof(*out_values)),
                                                &sz);

        if (IS_ERR(val))
                return PTR_ERR(val);

        if (!sz_max)
                sz = sz_min;
        else
                sz /= sizeof(*out_values);

        count = sz;
        while (count--)
                *out_values++ = *val++;

        return sz;
}
EXPORT_SYMBOL_GPL(of_property_read_variable_u8_array);

/**
 * of_property_read_variable_u16_array - Find and read an array of u16 from a
 * property, with bounds on the minimum and maximum array size.
 *
 * @np:         device node from which the property value is to be read.
 * @propname:   name of the property to be searched.
 * @out_values: pointer to return value, modified only if return value is 0.
 * @sz_min:     minimum number of array elements to read
 * @sz_max:     maximum number of array elements to read, if zero there is no
 *              upper limit on the number of elements in the dts entry but only
 *              sz_min will be read.
 *
 * Search for a property in a device node and read 16-bit value(s) from
 * it. Returns number of elements read on success, -EINVAL if the property
 * does not exist, -ENODATA if property does not have a value, and -EOVERFLOW
 * if the property data is smaller than sz_min or longer than sz_max.
 *
 * dts entry of array should be like:
 *      property = /bits/ 16 <0x5000 0x6000 0x7000>;
 *
 * The out_values is modified only if a valid u16 value can be decoded.
 */
int of_property_read_variable_u16_array(const struct device_node *np,
                                        const char *propname, u16 *out_values,
                                        size_t sz_min, size_t sz_max)
{
        size_t sz, count;
        const __be16 *val = of_find_property_value_of_size(np, propname,
                                                (sz_min * sizeof(*out_values)),
                                                (sz_max * sizeof(*out_values)),
                                                &sz);

        if (IS_ERR(val))
                return PTR_ERR(val);

        if (!sz_max)
                sz = sz_min;
        else
                sz /= sizeof(*out_values);

        count = sz;
        while (count--)
                *out_values++ = be16_to_cpup(val++);

        return sz;
}
EXPORT_SYMBOL_GPL(of_property_read_variable_u16_array);

/**
 * of_property_read_variable_u32_array - Find and read an array of 32 bit
 * integers from a property, with bounds on the minimum and maximum array size.
 *
 * @np:         device node from which the property value is to be read.
 * @propname:   name of the property to be searched.
 * @out_values: pointer to return value, modified only if return value is 0.
 * @sz_min:     minimum number of array elements to read
 * @sz_max:     maximum number of array elements to read, if zero there is no
 *              upper limit on the number of elements in the dts entry but only
 *              sz_min will be read.
 *
 * Search for a property in a device node and read 32-bit value(s) from
 * it. Returns number of elements read on success, -EINVAL if the property
 * does not exist, -ENODATA if property does not have a value, and -EOVERFLOW
 * if the property data is smaller than sz_min or longer than sz_max.
 *
 * The out_values is modified only if a valid u32 value can be decoded.
 */
int of_property_read_variable_u32_array(const struct device_node *np,
                               const char *propname, u32 *out_values,
                               size_t sz_min, size_t sz_max)
{
        size_t sz, count;
        const __be32 *val = of_find_property_value_of_size(np, propname,
                                                (sz_min * sizeof(*out_values)),
                                                (sz_max * sizeof(*out_values)),
                                                &sz);

        if (IS_ERR(val))
                return PTR_ERR(val);

        if (!sz_max)
                sz = sz_min;
        else
                sz /= sizeof(*out_values);

        count = sz;
        while (count--)
                *out_values++ = be32_to_cpup(val++);

        return sz;
}
EXPORT_SYMBOL_GPL(of_property_read_variable_u32_array);

/**
 * of_property_read_u64 - Find and read a 64 bit integer from a property
 * @np:         device node from which the property value is to be read.
 * @propname:   name of the property to be searched.
 * @out_value:  pointer to return value, modified only if return value is 0.
 *
 * Search for a property in a device node and read a 64-bit value from
 * it. Returns 0 on success, -EINVAL if the property does not exist,
 * -ENODATA if property does not have a value, and -EOVERFLOW if the
 * property data isn't large enough.
 *
 * The out_value is modified only if a valid u64 value can be decoded.
 */
int of_property_read_u64(const struct device_node *np, const char *propname,
                         u64 *out_value)
{
        const __be32 *val = of_find_property_value_of_size(np, propname,
                                                sizeof(*out_value),
                                                0,
                                                NULL);

        if (IS_ERR(val))
                return PTR_ERR(val);

        *out_value = of_read_number(val, 2);
        return 0;
}
EXPORT_SYMBOL_GPL(of_property_read_u64);

/**
 * of_property_read_variable_u64_array - Find and read an array of 64 bit
 * integers from a property, with bounds on the minimum and maximum array size.
 *
 * @np:         device node from which the property value is to be read.
 * @propname:   name of the property to be searched.
 * @out_values: pointer to return value, modified only if return value is 0.
 * @sz_min:     minimum number of array elements to read
 * @sz_max:     maximum number of array elements to read, if zero there is no
 *              upper limit on the number of elements in the dts entry but only
 *              sz_min will be read.
 *
 * Search for a property in a device node and read 64-bit value(s) from
 * it. Returns number of elements read on success, -EINVAL if the property
 * does not exist, -ENODATA if property does not have a value, and -EOVERFLOW
 * if the property data is smaller than sz_min or longer than sz_max.
 *
 * The out_values is modified only if a valid u64 value can be decoded.
 */
int of_property_read_variable_u64_array(const struct device_node *np,
                               const char *propname, u64 *out_values,
                               size_t sz_min, size_t sz_max)
{
        size_t sz, count;
        const __be32 *val = of_find_property_value_of_size(np, propname,
                                                (sz_min * sizeof(*out_values)),
                                                (sz_max * sizeof(*out_values)),
                                                &sz);

        if (IS_ERR(val))
                return PTR_ERR(val);

        if (!sz_max)
                sz = sz_min;
        else
                sz /= sizeof(*out_values);

        count = sz;
        while (count--) {
                *out_values++ = of_read_number(val, 2);
                val += 2;
        }

        return sz;
}
EXPORT_SYMBOL_GPL(of_property_read_variable_u64_array);

/**
 * of_property_read_string - Find and read a string from a property
 * @np:         device node from which the property value is to be read.
 * @propname:   name of the property to be searched.
 * @out_string: pointer to null terminated return string, modified only if
 *              return value is 0.
 *
 * Search for a property in a device tree node and retrieve a null
 * terminated string value (pointer to data, not a copy). Returns 0 on
 * success, -EINVAL if the property does not exist, -ENODATA if property
 * does not have a value, and -EILSEQ if the string is not null-terminated
 * within the length of the property data.
 *
 * The out_string pointer is modified only if a valid string can be decoded.
 */
int of_property_read_string(const struct device_node *np, const char *propname,
                                const char **out_string)
{
        const struct property *prop = of_find_property(np, propname, NULL);
        if (!prop)
                return -EINVAL;
        if (!prop->value)
                return -ENODATA;
        if (strnlen(prop->value, prop->length) >= prop->length)
                return -EILSEQ;
        *out_string = prop->value;
        return 0;
}
EXPORT_SYMBOL_GPL(of_property_read_string);

/**
 * of_property_match_string() - Find string in a list and return index
 * @np: pointer to node containing string list property
 * @propname: string list property name
 * @string: pointer to string to search for in string list
 *
 * This function searches a string list property and returns the index
 * of a specific string value.
 */
int of_property_match_string(const struct device_node *np, const char *propname,
                             const char *string)
{
        const struct property *prop = of_find_property(np, propname, NULL);
        size_t l;
        int i;
        const char *p, *end;

        if (!prop)
                return -EINVAL;
        if (!prop->value)
                return -ENODATA;

        p = prop->value;
        end = p + prop->length;

        for (i = 0; p < end; i++, p += l) {
                l = strnlen(p, end - p) + 1;
                if (p + l > end)
                        return -EILSEQ;
                pr_debug("comparing %s with %s\n", string, p);
                if (strcmp(string, p) == 0)
                        return i; /* Found it; return index */
        }
        return -ENODATA;
}
EXPORT_SYMBOL_GPL(of_property_match_string);

/**
 * of_property_read_string_helper() - Utility helper for parsing string properties
 * @np:         device node from which the property value is to be read.
 * @propname:   name of the property to be searched.
 * @out_strs:   output array of string pointers.
 * @sz:         number of array elements to read.
 * @skip:       Number of strings to skip over at beginning of list.
 *
 * Don't call this function directly. It is a utility helper for the
 * of_property_read_string*() family of functions.
 */
int of_property_read_string_helper(const struct device_node *np,
                                   const char *propname, const char **out_strs,
                                   size_t sz, int skip)
{
        const struct property *prop = of_find_property(np, propname, NULL);
        int l = 0, i = 0;
        const char *p, *end;

        if (!prop)
                return -EINVAL;
        if (!prop->value)
                return -ENODATA;
        p = prop->value;
        end = p + prop->length;

        for (i = 0; p < end && (!out_strs || i < skip + sz); i++, p += l) {
                l = strnlen(p, end - p) + 1;
                if (p + l > end)
                        return -EILSEQ;
                if (out_strs && i >= skip)
                        *out_strs++ = p;
        }
        i -= skip;
        return i <= 0 ? -ENODATA : i;
}
EXPORT_SYMBOL_GPL(of_property_read_string_helper);

void of_print_phandle_args(const char *msg, const struct of_phandle_args *args)
{
        int i;
        printk("%s %s", msg, of_node_full_name(args->np));
        for (i = 0; i < args->args_count; i++)
                printk(i ? ",%08x" : ":%08x", args->args[i]);
        printk("\n");
}

int of_phandle_iterator_init(struct of_phandle_iterator *it,
                const struct device_node *np,
                const char *list_name,
                const char *cells_name,
                int cell_count)
{
        const __be32 *list;
        int size;

        memset(it, 0, sizeof(*it));

        list = of_get_property(np, list_name, &size);
        if (!list)
                return -ENOENT;

        it->cells_name = cells_name;
        it->cell_count = cell_count;
        it->parent = np;
        it->list_end = list + size / sizeof(*list);
        it->phandle_end = list;
        it->cur = list;

        return 0;
}

int of_phandle_iterator_next(struct of_phandle_iterator *it)
{
        uint32_t count = 0;

        if (it->node) {
                of_node_put(it->node);
                it->node = NULL;
        }

        if (!it->cur || it->phandle_end >= it->list_end)
                return -ENOENT;

        it->cur = it->phandle_end;

        /* If phandle is 0, then it is an empty entry with no arguments. */
        it->phandle = be32_to_cpup(it->cur++);

        if (it->phandle) {

                /*
                 * Find the provider node and parse the #*-cells property to
                 * determine the argument length.
                 */
                it->node = of_find_node_by_phandle(it->phandle);

                if (it->cells_name) {
                        if (!it->node) {
                                pr_err("%s: could not find phandle\n",
                                       it->parent->full_name);
                                goto err;
                        }

                        if (of_property_read_u32(it->node, it->cells_name,
                                                 &count)) {
                                pr_err("%s: could not get %s for %s\n",
                                       it->parent->full_name,
                                       it->cells_name,
                                       it->node->full_name);
                                goto err;
                        }
                } else {
                        count = it->cell_count;
                }

                /*
                 * Make sure that the arguments actually fit in the remaining
                 * property data length
                 */
                if (it->cur + count > it->list_end) {
                        pr_err("%s: arguments longer than property\n",
                               it->parent->full_name);
                        goto err;
                }
        }

        it->phandle_end = it->cur + count;
        it->cur_count = count;

        return 0;

err:
        if (it->node) {
                of_node_put(it->node);
                it->node = NULL;
        }

        return -EINVAL;
}

int of_phandle_iterator_args(struct of_phandle_iterator *it,
                             uint32_t *args,
                             int size)
{
        int i, count;

        count = it->cur_count;

        if (WARN_ON(size < count))
                count = size;

        for (i = 0; i < count; i++)
                args[i] = be32_to_cpup(it->cur++);

        return count;
}

static int __of_parse_phandle_with_args(const struct device_node *np,
                                        const char *list_name,
                                        const char *cells_name,
                                        int cell_count, int index,
                                        struct of_phandle_args *out_args)
{
        struct of_phandle_iterator it;
        int rc, cur_index = 0;

        /* Loop over the phandles until all the requested entry is found */
        of_for_each_phandle(&it, rc, np, list_name, cells_name, cell_count) {
                /*
                 * All of the error cases bail out of the loop, so at
                 * this point, the parsing is successful. If the requested
                 * index matches, then fill the out_args structure and return,
                 * or return -ENOENT for an empty entry.
                 */
                rc = -ENOENT;
                if (cur_index == index) {
                        if (!it.phandle)
                                goto err;

                        if (out_args) {
                                int c;

                                c = of_phandle_iterator_args(&it,
                                                             out_args->args,
                                                             MAX_PHANDLE_ARGS);
                                out_args->np = it.node;
                                out_args->args_count = c;
                        } else {
                                of_node_put(it.node);
                        }

                        /* Found it! return success */
                        return 0;
                }

                cur_index++;
        }

        /*
         * Unlock node before returning result; will be one of:
         * -ENOENT : index is for empty phandle
         * -EINVAL : parsing error on data
         */

 err:
        of_node_put(it.node);
        return rc;
}

/**
 * of_parse_phandle - Resolve a phandle property to a device_node pointer
 * @np: Pointer to device node holding phandle property
 * @phandle_name: Name of property holding a phandle value
 * @index: For properties holding a table of phandles, this is the index into
 *         the table
 *
 * Returns the device_node pointer with refcount incremented.  Use
 * of_node_put() on it when done.
 */
struct device_node *of_parse_phandle(const struct device_node *np,
                                     const char *phandle_name, int index)
{
        struct of_phandle_args args;

        if (index < 0)
                return NULL;

        if (__of_parse_phandle_with_args(np, phandle_name, NULL, 0,
                                         index, &args))
                return NULL;

        return args.np;
}
EXPORT_SYMBOL(of_parse_phandle);

/**
 * of_parse_phandle_with_args() - Find a node pointed by phandle in a list
 * @np:         pointer to a device tree node containing a list
 * @list_name:  property name that contains a list
 * @cells_name: property name that specifies phandles' arguments count
 * @index:      index of a phandle to parse out
 * @out_args:   optional pointer to output arguments structure (will be filled)
 *
 * This function is useful to parse lists of phandles and their arguments.
 * Returns 0 on success and fills out_args, on error returns appropriate
 * errno value.
 *
 * Caller is responsible to call of_node_put() on the returned out_args->np
 * pointer.
 *
 * Example:
 *
 * phandle1: node1 {
 *      #list-cells = <2>;
 * }
 *
 * phandle2: node2 {
 *      #list-cells = <1>;
 * }
 *
 * node3 {
 *      list = <&phandle1 1 2 &phandle2 3>;
 * }
 *
 * To get a device_node of the `node2' node you may call this:
 * of_parse_phandle_with_args(node3, "list", "#list-cells", 1, &args);
 */
int of_parse_phandle_with_args(const struct device_node *np, const char *list_name,
                                const char *cells_name, int index,
                                struct of_phandle_args *out_args)
{
        if (index < 0)
                return -EINVAL;
        return __of_parse_phandle_with_args(np, list_name, cells_name, 0,
                                            index, out_args);
}
EXPORT_SYMBOL(of_parse_phandle_with_args);

/**
 * of_parse_phandle_with_fixed_args() - Find a node pointed by phandle in a list
 * @np:         pointer to a device tree node containing a list
 * @list_name:  property name that contains a list
 * @cell_count: number of argument cells following the phandle
 * @index:      index of a phandle to parse out
 * @out_args:   optional pointer to output arguments structure (will be filled)
 *
 * This function is useful to parse lists of phandles and their arguments.
 * Returns 0 on success and fills out_args, on error returns appropriate
 * errno value.
 *
 * Caller is responsible to call of_node_put() on the returned out_args->np
 * pointer.
 *
 * Example:
 *
 * phandle1: node1 {
 * }
 *
 * phandle2: node2 {
 * }
 *
 * node3 {
 *      list = <&phandle1 0 2 &phandle2 2 3>;
 * }
 *
 * To get a device_node of the `node2' node you may call this:
 * of_parse_phandle_with_fixed_args(node3, "list", 2, 1, &args);
 */
int of_parse_phandle_with_fixed_args(const struct device_node *np,
                                const char *list_name, int cell_count,
                                int index, struct of_phandle_args *out_args)
{
        if (index < 0)
                return -EINVAL;
        return __of_parse_phandle_with_args(np, list_name, NULL, cell_count,
                                           index, out_args);
}
EXPORT_SYMBOL(of_parse_phandle_with_fixed_args);

/**
 * of_count_phandle_with_args() - Find the number of phandles references in a property
 * @np:         pointer to a device tree node containing a list
 * @list_name:  property name that contains a list
 * @cells_name: property name that specifies phandles' arguments count
 *
 * Returns the number of phandle + argument tuples within a property. It
 * is a typical pattern to encode a list of phandle and variable
 * arguments into a single property. The number of arguments is encoded
 * by a property in the phandle-target node. For example, a gpios
 * property would contain a list of GPIO specifies consisting of a
 * phandle and 1 or more arguments. The number of arguments are
 * determined by the #gpio-cells property in the node pointed to by the
 * phandle.
 */
int of_count_phandle_with_args(const struct device_node *np, const char *list_name,
                                const char *cells_name)
{
        struct of_phandle_iterator it;
        int rc, cur_index = 0;

        rc = of_phandle_iterator_init(&it, np, list_name, cells_name, 0);
        if (rc)
                return rc;

        while ((rc = of_phandle_iterator_next(&it)) == 0)
                cur_index += 1;

        if (rc != -ENOENT)
                return rc;

        return cur_index;
}
EXPORT_SYMBOL(of_count_phandle_with_args);

/**
 * __of_add_property - Add a property to a node without lock operations
 */
int __of_add_property(struct device_node *np, struct property *prop)
{
        struct property **next;

        prop->next = NULL;
        next = &np->properties;
        while (*next) {
                if (strcmp(prop->name, (*next)->name) == 0)
                        /* duplicate ! don't insert it */
                        return -EEXIST;

                next = &(*next)->next;
        }
        *next = prop;

        return 0;
}

/**
 * of_add_property - Add a property to a node
 */
int of_add_property(struct device_node *np, struct property *prop)
{
        unsigned long flags;
        int rc;

        mutex_lock(&of_mutex);

        raw_spin_lock_irqsave(&devtree_lock, flags);
        rc = __of_add_property(np, prop);
        raw_spin_unlock_irqrestore(&devtree_lock, flags);

        if (!rc)
                __of_add_property_sysfs(np, prop);

        mutex_unlock(&of_mutex);

        if (!rc)
                of_property_notify(OF_RECONFIG_ADD_PROPERTY, np, prop, NULL);

        return rc;
}

int __of_remove_property(struct device_node *np, struct property *prop)
{
        struct property **next;

        for (next = &np->properties; *next; next = &(*next)->next) {
                if (*next == prop)
                        break;
        }
        if (*next == NULL)
                return -ENODEV;

        /* found the node */
        *next = prop->next;
        prop->next = np->deadprops;
        np->deadprops = prop;

        return 0;
}

void __of_sysfs_remove_bin_file(struct device_node *np, struct property *prop)
{
        sysfs_remove_bin_file(&np->kobj, &prop->attr);
        kfree(prop->attr.attr.name);
}

void __of_remove_property_sysfs(struct device_node *np, struct property *prop)
{
        if (!IS_ENABLED(CONFIG_SYSFS))
                return;

        /* at early boot, bail here and defer setup to of_init() */
        if (of_kset && of_node_is_attached(np))
                __of_sysfs_remove_bin_file(np, prop);
}

/**
 * of_remove_property - Remove a property from a node.
 *
 * Note that we don't actually remove it, since we have given out
 * who-knows-how-many pointers to the data using get-property.
 * Instead we just move the property to the "dead properties"
 * list, so it won't be found any more.
 */
int of_remove_property(struct device_node *np, struct property *prop)
{
        unsigned long flags;
        int rc;

        if (!prop)
                return -ENODEV;

        mutex_lock(&of_mutex);

        raw_spin_lock_irqsave(&devtree_lock, flags);
        rc = __of_remove_property(np, prop);
        raw_spin_unlock_irqrestore(&devtree_lock, flags);

        if (!rc)
                __of_remove_property_sysfs(np, prop);

        mutex_unlock(&of_mutex);

        if (!rc)
                of_property_notify(OF_RECONFIG_REMOVE_PROPERTY, np, prop, NULL);

        return rc;
}

int __of_update_property(struct device_node *np, struct property *newprop,
                struct property **oldpropp)
{
        struct property **next, *oldprop;

        for (next = &np->properties; *next; next = &(*next)->next) {
                if (of_prop_cmp((*next)->name, newprop->name) == 0)
                        break;
        }
        *oldpropp = oldprop = *next;

        if (oldprop) {
                /* replace the node */
                newprop->next = oldprop->next;
                *next = newprop;
                oldprop->next = np->deadprops;
                np->deadprops = oldprop;
        } else {
                /* new node */
                newprop->next = NULL;
                *next = newprop;
        }

        return 0;
}

void __of_update_property_sysfs(struct device_node *np, struct property *newprop,
                struct property *oldprop)
{
        if (!IS_ENABLED(CONFIG_SYSFS))
                return;

        /* At early boot, bail out and defer setup to of_init() */
        if (!of_kset)
                return;

        if (oldprop)
                __of_sysfs_remove_bin_file(np, oldprop);
        __of_add_property_sysfs(np, newprop);
}

/*
 * of_update_property - Update a property in a node, if the property does
 * not exist, add it.
 *
 * Note that we don't actually remove it, since we have given out
 * who-knows-how-many pointers to the data using get-property.
 * Instead we just move the property to the "dead properties" list,
 * and add the new property to the property list
 */
int of_update_property(struct device_node *np, struct property *newprop)
{
        struct property *oldprop;
        unsigned long flags;
        int rc;

        if (!newprop->name)
                return -EINVAL;

        mutex_lock(&of_mutex);

        raw_spin_lock_irqsave(&devtree_lock, flags);
        rc = __of_update_property(np, newprop, &oldprop);
        raw_spin_unlock_irqrestore(&devtree_lock, flags);

        if (!rc)
                __of_update_property_sysfs(np, newprop, oldprop);

        mutex_unlock(&of_mutex);

        if (!rc)
                of_property_notify(OF_RECONFIG_UPDATE_PROPERTY, np, newprop, oldprop);

        return rc;
}

static void of_alias_add(struct alias_prop *ap, struct device_node *np,
                         int id, const char *stem, int stem_len)
{
        ap->np = np;
        ap->id = id;
        strncpy(ap->stem, stem, stem_len);
        ap->stem[stem_len] = 0;
        list_add_tail(&ap->link, &aliases_lookup);
        pr_debug("adding DT alias:%s: stem=%s id=%i node=%s\n",
                 ap->alias, ap->stem, ap->id, of_node_full_name(np));
}

/**
 * of_alias_scan - Scan all properties of the 'aliases' node
 *
 * The function scans all the properties of the 'aliases' node and populates
 * the global lookup table with the properties.  It returns the
 * number of alias properties found, or an error code in case of failure.
 *
 * @dt_alloc:   An allocator that provides a virtual address to memory
 *              for storing the resulting tree
 */
void of_alias_scan(void * (*dt_alloc)(u64 size, u64 align))
{
        struct property *pp;

        of_aliases = of_find_node_by_path("/aliases");
        of_chosen = of_find_node_by_path("/chosen");
        if (of_chosen == NULL)
                of_chosen = of_find_node_by_path("/chosen@0");

        if (of_chosen) {
                /* linux,stdout-path and /aliases/stdout are for legacy compatibility */
                const char *name = of_get_property(of_chosen, "stdout-path", NULL);
                if (!name)
                        name = of_get_property(of_chosen, "linux,stdout-path", NULL);
                if (IS_ENABLED(CONFIG_PPC) && !name)
                        name = of_get_property(of_aliases, "stdout", NULL);
                if (name)
                        of_stdout = of_find_node_opts_by_path(name, &of_stdout_options);
                if (of_stdout)
                        console_set_by_of();
        }

        if (!of_aliases)
                return;

        for_each_property_of_node(of_aliases, pp) {
                const char *start = pp->name;
                const char *end = start + strlen(start);
                struct device_node *np;
                struct alias_prop *ap;
                int id, len;

                /* Skip those we do not want to proceed */
                if (!strcmp(pp->name, "name") ||
                    !strcmp(pp->name, "phandle") ||
                    !strcmp(pp->name, "linux,phandle"))
                        continue;

                np = of_find_node_by_path(pp->value);
                if (!np)
                        continue;

                /* walk the alias backwards to extract the id and work out
                 * the 'stem' string */
                while (isdigit(*(end-1)) && end > start)
                        end--;
                len = end - start;

                if (kstrtoint(end, 10, &id) < 0)
                        continue;

                /* Allocate an alias_prop with enough space for the stem */
                ap = dt_alloc(sizeof(*ap) + len + 1, 4);
                if (!ap)
                        continue;
                memset(ap, 0, sizeof(*ap) + len + 1);
                ap->alias = start;
                of_alias_add(ap, np, id, start, len);
        }
}

/**
 * of_alias_get_id - Get alias id for the given device_node
 * @np:         Pointer to the given device_node
 * @stem:       Alias stem of the given device_node
 *
 * The function travels the lookup table to get the alias id for the given
 * device_node and alias stem.  It returns the alias id if found.
 */
int of_alias_get_id(struct device_node *np, const char *stem)
{
        struct alias_prop *app;
        int id = -ENODEV;

        mutex_lock(&of_mutex);
        list_for_each_entry(app, &aliases_lookup, link) {
                if (strcmp(app->stem, stem) != 0)
                        continue;

                if (np == app->np) {
                        id = app->id;
                        break;
                }
        }
        mutex_unlock(&of_mutex);

        return id;
}
EXPORT_SYMBOL_GPL(of_alias_get_id);

/**
 * of_alias_get_highest_id - Get highest alias id for the given stem
 * @stem:       Alias stem to be examined
 *
 * The function travels the lookup table to get the highest alias id for the
 * given alias stem.  It returns the alias id if found.
 */
int of_alias_get_highest_id(const char *stem)
{
        struct alias_prop *app;
        int id = -ENODEV;

        mutex_lock(&of_mutex);
        list_for_each_entry(app, &aliases_lookup, link) {
                if (strcmp(app->stem, stem) != 0)
                        continue;

                if (app->id > id)
                        id = app->id;
        }
        mutex_unlock(&of_mutex);

        return id;
}
EXPORT_SYMBOL_GPL(of_alias_get_highest_id);

const __be32 *of_prop_next_u32(struct property *prop, const __be32 *cur,
                               u32 *pu)
{
        const void *curv = cur;

        if (!prop)
                return NULL;

        if (!cur) {
                curv = prop->value;
                goto out_val;
        }

        curv += sizeof(*cur);
        if (curv >= prop->value + prop->length)
                return NULL;

out_val:
        *pu = be32_to_cpup(curv);
        return curv;
}
EXPORT_SYMBOL_GPL(of_prop_next_u32);

const char *of_prop_next_string(struct property *prop, const char *cur)
{
        const void *curv = cur;

        if (!prop)
                return NULL;

        if (!cur)
                return prop->value;

        curv += strlen(cur) + 1;
        if (curv >= prop->value + prop->length)
                return NULL;

        return curv;
}
EXPORT_SYMBOL_GPL(of_prop_next_string);

/**
 * of_console_check() - Test and setup console for DT setup
 * @dn - Pointer to device node
 * @name - Name to use for preferred console without index. ex. "ttyS"
 * @index - Index to use for preferred console.
 *
 * Check if the given device node matches the stdout-path property in the
 * /chosen node. If it does then register it as the preferred console and return
 * TRUE. Otherwise return FALSE.
 */
bool of_console_check(struct device_node *dn, char *name, int index)
{
        if (!dn || dn != of_stdout || console_set_on_cmdline)
                return false;
        return !add_preferred_console(name, index,
                                      kstrdup(of_stdout_options, GFP_KERNEL));
}
EXPORT_SYMBOL_GPL(of_console_check);

/**
 *      of_find_next_cache_node - Find a node's subsidiary cache
 *      @np:    node of type "cpu" or "cache"
 *
 *      Returns a node pointer with refcount incremented, use
 *      of_node_put() on it when done.  Caller should hold a reference
 *      to np.
 */
struct device_node *of_find_next_cache_node(const struct device_node *np)
{
        struct device_node *child;
        const phandle *handle;

        handle = of_get_property(np, "l2-cache", NULL);
        if (!handle)
                handle = of_get_property(np, "next-level-cache", NULL);

        if (handle)
                return of_find_node_by_phandle(be32_to_cpup(handle));

        /* OF on pmac has nodes instead of properties named "l2-cache"
         * beneath CPU nodes.
         */
        if (!strcmp(np->type, "cpu"))
                for_each_child_of_node(np, child)
                        if (!strcmp(child->type, "cache"))
                                return child;

        return NULL;
}

/**
 * of_graph_parse_endpoint() - parse common endpoint node properties
 * @node: pointer to endpoint device_node
 * @endpoint: pointer to the OF endpoint data structure
 *
 * The caller should hold a reference to @node.
 */
int of_graph_parse_endpoint(const struct device_node *node,
                            struct of_endpoint *endpoint)
{
        struct device_node *port_node = of_get_parent(node);

        WARN_ONCE(!port_node, "%s(): endpoint %s has no parent node\n",
                  __func__, node->full_name);

        memset(endpoint, 0, sizeof(*endpoint));

        endpoint->local_node = node;
        /*
         * It doesn't matter whether the two calls below succeed.
         * If they don't then the default value 0 is used.
         */
        of_property_read_u32(port_node, "reg", &endpoint->port);
        of_property_read_u32(node, "reg", &endpoint->id);

        of_node_put(port_node);

        return 0;
}
EXPORT_SYMBOL(of_graph_parse_endpoint);

/**
 * of_graph_get_port_by_id() - get the port matching a given id
 * @parent: pointer to the parent device node
 * @id: id of the port
 *
 * Return: A 'port' node pointer with refcount incremented. The caller
 * has to use of_node_put() on it when done.
 */
struct device_node *of_graph_get_port_by_id(struct device_node *parent, u32 id)
{
        struct device_node *node, *port;

        node = of_get_child_by_name(parent, "ports");
        if (node)
                parent = node;

        for_each_child_of_node(parent, port) {
                u32 port_id = 0;

                if (of_node_cmp(port->name, "port") != 0)
                        continue;
                of_property_read_u32(port, "reg", &port_id);
                if (id == port_id)
                        break;
        }

        of_node_put(node);

        return port;
}
EXPORT_SYMBOL(of_graph_get_port_by_id);

/**
 * of_graph_get_next_endpoint() - get next endpoint node
 * @parent: pointer to the parent device node
 * @prev: previous endpoint node, or NULL to get first
 *
 * Return: An 'endpoint' node pointer with refcount incremented. Refcount
 * of the passed @prev node is decremented.
 */
struct device_node *of_graph_get_next_endpoint(const struct device_node *parent,
                                        struct device_node *prev)
{
        struct device_node *endpoint;
        struct device_node *port;

        if (!parent)
                return NULL;

        /*
         * Start by locating the port node. If no previous endpoint is specified
         * search for the first port node, otherwise get the previous endpoint
         * parent port node.
         */
        if (!prev) {
                struct device_node *node;

                node = of_get_child_by_name(parent, "ports");
                if (node)
                        parent = node;

                port = of_get_child_by_name(parent, "port");
                of_node_put(node);

                if (!port) {
                        pr_err("graph: no port node found in %s\n",
                               parent->full_name);
                        return NULL;
                }
        } else {
                port = of_get_parent(prev);
                if (WARN_ONCE(!port, "%s(): endpoint %s has no parent node\n",
                              __func__, prev->full_name))
                        return NULL;
        }

        while (1) {
                /*
                 * Now that we have a port node, get the next endpoint by
                 * getting the next child. If the previous endpoint is NULL this
                 * will return the first child.
                 */
                endpoint = of_get_next_child(port, prev);
                if (endpoint) {
                        of_node_put(port);
                        return endpoint;
                }

                /* No more endpoints under this port, try the next one. */
                prev = NULL;

                do {
                        port = of_get_next_child(parent, port);
                        if (!port)
                                return NULL;
                } while (of_node_cmp(port->name, "port"));
        }
}
EXPORT_SYMBOL(of_graph_get_next_endpoint);

/**
 * of_graph_get_endpoint_by_regs() - get endpoint node of specific identifiers
 * @parent: pointer to the parent device node
 * @port_reg: identifier (value of reg property) of the parent port node
 * @reg: identifier (value of reg property) of the endpoint node
 *
 * Return: An 'endpoint' node pointer which is identified by reg and at the same
 * is the child of a port node identified by port_reg. reg and port_reg are
 * ignored when they are -1.
 */
struct device_node *of_graph_get_endpoint_by_regs(
        const struct device_node *parent, int port_reg, int reg)
{
        struct of_endpoint endpoint;
        struct device_node *node = NULL;

        for_each_endpoint_of_node(parent, node) {
                of_graph_parse_endpoint(node, &endpoint);
                if (((port_reg == -1) || (endpoint.port == port_reg)) &&
                        ((reg == -1) || (endpoint.id == reg)))
                        return node;
        }

        return NULL;
}
EXPORT_SYMBOL(of_graph_get_endpoint_by_regs);

/**
 * of_graph_get_remote_port_parent() - get remote port's parent node
 * @node: pointer to a local endpoint device_node
 *
 * Return: Remote device node associated with remote endpoint node linked
 *         to @node. Use of_node_put() on it when done.
 */
struct device_node *of_graph_get_remote_port_parent(
                               const struct device_node *node)
{
        struct device_node *np;
        unsigned int depth;

        /* Get remote endpoint node. */
        np = of_parse_phandle(node, "remote-endpoint", 0);

        /* Walk 3 levels up only if there is 'ports' node. */
        for (depth = 3; depth && np; depth--) {
                np = of_get_next_parent(np);
                if (depth == 2 && of_node_cmp(np->name, "ports"))
                        break;
        }
        return np;
}
EXPORT_SYMBOL(of_graph_get_remote_port_parent);

/**
 * of_graph_get_remote_port() - get remote port node
 * @node: pointer to a local endpoint device_node
 *
 * Return: Remote port node associated with remote endpoint node linked
 *         to @node. Use of_node_put() on it when done.
 */
struct device_node *of_graph_get_remote_port(const struct device_node *node)
{
        struct device_node *np;

        /* Get remote endpoint node. */
        np = of_parse_phandle(node, "remote-endpoint", 0);
        if (!np)
                return NULL;
        return of_get_next_parent(np);
}
EXPORT_SYMBOL(of_graph_get_remote_port);